JP2006301570A - Transparent film, method for manufacturing transparent film, optical compensating film, polarizing plate, and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transparent film, of which the optical anisotropy is small and which is substantially optically isotropic, of which the optical characteristics are uniform and has little unevenness, and which is suited for a liquid crystal display device. <P>SOLUTION: In the width direction of the transparent film, an in-plane retardation value (Rec) of a film center portion is 20 nm or smaller, an absolute value of a retardation value Rthc in the film thickness direction of the film center portion is 20 nm or smaller. Furthermore, in the transparent film, the absolute value of the difference between Rec and a retardation value (Ree) at a film end portion is 1.5 nm or smaller (1a), or the absolute value of the slope of in-plane retardation value in the width direction from the film end portion to the film center portion is 0.5 nm/m or smaller (2b), or the standard deviation of the in-plane retardation value in the width direction is 0.25 nm or smaller (3c). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a transparent film useful for a liquid crystal display device and a method for producing the same, and further relates to an optical material using the same, an optical material such as a polarizing plate, and a liquid crystal display device.

  Conventionally, cellulose acylate films have been used for photographic supports and various optical materials because of their toughness and flame retardancy. In particular, in recent years, it has been widely used as an optical transparent film for liquid crystal display devices. Cellulose acylate films are excellent as optical materials for devices that handle polarized light such as liquid crystal display devices because of their high optical transparency and high optical isotropy. It has been used as a support for optical protective films that can improve (viewing angle compensation) a protective film and a display viewed from an oblique direction.

  A polarizing plate, which is one of the members for a liquid crystal display device, has a polarizer protective film bonded to at least one side of the polarizer. A general polarizer is obtained by dyeing a stretched polyvinyl alcohol (PVA) film with iodine or a dichroic dye. In many cases, as a polarizer protective film, a cellulose acylate film, particularly a triacetyl cellulose film, which can be directly bonded to PVA is used. It is important that the polarizer protective film is excellent in optical isotropy, and the optical characteristics of the polarizer protective film greatly affect the characteristics of the polarizing plate.

  In recent liquid crystal display devices, improvement in viewing angle characteristics is strongly demanded, and optical transparent films such as a protective film for a polarizer and a support for an optical compensation film are more optically isotropic. It is required to be sex. In order to be optically isotropic, it is important that the retardation value represented by the product of birefringence and thickness of the optical film is small. In particular, in order to improve the display from an oblique direction, it is necessary to reduce not only the in-plane retardation (Re) but also the retardation in the film thickness direction (Rth). Specifically, when the optical properties of the optical transparent film are evaluated, the Re measured from the front of the film is small, and it is required that the Re does not change even if the angle is changed.

  So far, there has been a cellulose acylate film with a small Re on the front, but it was difficult to produce a cellulose acylate film with a small Re change with angle, that is, a small Rth. Therefore, an optical transparent film having a small angle change of Re using a polycarbonate film or a thermoplastic cycloolefin film instead of a cellulose acylate film has been proposed (for example, Patent Documents 1 and 2, ZEONOR ( Zeon Corporation), ARTON (JSR Corporation), etc.). However, when these optically transparent films are used as a protective film for a polarizer, the film is hydrophobic, so that there are problems in terms of bonding with PVA, chips during cutting, and the like. There also remains a problem that the optical characteristics of the entire film surface are non-uniform.

  As a solution to this problem, it is strongly desired to improve the cellulose acylate film which is excellent in the bonding property to PVA by further reducing the optical anisotropy. Specifically, it is an optically isotropic optically transparent film in which Re on the front surface of the cellulose acylate film is substantially zero and the change in retardation angle is small, that is, Rth is also substantially zero.

  In the production of a cellulose acylate film, a compound called a plasticizer is generally added to improve the film forming performance. As types of plasticizers, phosphate triesters such as triphenyl phosphate and biphenyl diphenyl phosphate, phthalates, and the like are disclosed (for example, see Non-Patent Document 1). Among these plasticizers, those having the effect of reducing the optical anisotropy of the cellulose acylate film are known. For example, specific fatty acid esters are disclosed (for example, see Patent Document 3). ). However, the effect of reducing the optical anisotropy of cellulose acylate films using these conventionally known compounds is not sufficient.

  In addition, the demand for large-sized display devices has increased, and development of large-sized liquid crystal display devices has been actively promoted, and the demand for large-width optical transparent films used therefor has been rapidly increasing. A wide film is also expected from the viewpoint of productivity. However, in order to obtain a film having uniform optical characteristics, it is necessary to produce the film by constantly maintaining various conditions such as temperature and tension in the film forming process. However, in continuously producing films having a film width of 1400 mm or more and a length of 100 m or more, it is industrially very difficult to keep all the steps at uniform conditions. In order to maintain a uniform display within the surface of the display device, strict uniformity is also required for the optical characteristics of the film used in the display device, and a solution is required.

Patent Document 4 discloses an example of producing a film having a small in-plane retardation value Re and a small variation using a specific polymer other than cellulose acylate, but the retardation value Rth in the film thickness direction is disclosed. However, the conventionally known methods cannot sufficiently achieve both reduction in retardation in the film thickness direction and reduction in variation. Further, Patent Document 5 discloses a method for producing a film with small variations in retardation.
JP 2001-318233 A JP 2002-328233 A JP 2001-247717 A JP 2002-293958 A JP 2001-272537 A Plastic Materials Course, Volume 17, Nikkan Kogyo Shimbun, “Fiber-Based Resin”, p. 121 (Showa 45)

  An object of the present invention is to provide a transparent film having very small retardation in the plane and in the film thickness direction and small variations thereof. Another object of the present invention is to provide a wide transparent film that is advantageous in production. Another object of the present invention is to provide an optical compensation film having a small display unevenness using the transparent film, an optical component such as a polarizing plate, and a liquid crystal display device.

  In order to solve the above-mentioned problems, the present inventors have conducted intensive research, for example, by using a polymer having a specific structure and composition, appropriately adjusting various prescription conditions, process conditions, etc. during production, etc. The present invention has been completed by solving the problems, finding that it is possible to obtain a transparent film in which retardation in the plane and in the film thickness direction hardly occurs and the unevenness of the retardation is very small. That is, according to the transparent film, the absolute value of retardation is small and the unevenness is small. Therefore, when incorporated in a liquid crystal display device, color unevenness and contrast unevenness are substantially observed over the entire display portion. Since it does not occur, it has been found that the image quality of the liquid crystal display device can be made very excellent, and the present invention has been achieved.

  Specifically, the above-described problems are solved by the following invention.

(1) In the width direction of the transparent film, the in-plane retardation value (Rec) at the center of the film is 20 nm or less, and the absolute value of the thickness direction retardation value (Rthc) at the center of the film is 20 nm or less. And the transparent film characterized by satisfy | filling at least any one of the following conditions (a1), (a2), (a3).
(A1) The absolute value of the difference between Rec and the in-plane retardation value (Ree) at the film edge is 1.5 nm or less.
(A2) The absolute value of the slope of the in-plane retardation value Re from the film edge to the film center in the width direction is 0.5 nm / m or less.
(A3) The standard deviation of the in-plane retardation value Re in the width direction is 0.25 nm or less.
(2) The transparent film according to (1), wherein at least one of the following conditions (a4), (a5), and (a6) is satisfied.
(A4) The absolute value of the difference between the Rthc and the film thickness direction retardation value (Rthe) at the film edge is 5 nm or less.
(A5) The absolute value of the gradient of the film thickness direction retardation value Rth from the film edge to the film center in the width direction is 5 nm / m or less.
(A6) The standard deviation of the film thickness direction retardation value Rth in the width direction is 2.5 nm or less.
(3) The transparent film according to (1) or (2), wherein Re of the film satisfies the following condition (a7).
(a7) 0.0001> sin ² (2θ) sin ² (πRe / λ)
(Θ is the angle (radian) formed between the slow axis direction in the film plane and the film forming direction (straight direction of the film), λ is the wavelength of light (nm) when measuring the three-dimensional refractive index, and π is a circle. (Period.)
(4) The transparent film according to any one of (1) to (3), wherein the width is from 1000 mm to 5000 mm and the length is from 100 m to 10000 m.
(5) Cellulose acylate having an acyl substitution degree of 2.85 to 3.00 contains at least one compound that lowers Re and Rth in an amount of 0.01 to 30% by weight based on the solid content of cellulose acylate. The transparent film according to any one of (1) to (4), which is characterized.
(6) The acyl substituent of the cellulose acylate is an acetyl group, the total substitution degree is 2.85 to 2.95, and the average polymerization degree is 180 to 550. (5) Description Transparent film.
(7) The transparent film as described in (5), wherein the acyl substituent comprises at least two kinds of acetyl group / propionyl group / butanoyl group.
(8) A compound that decreases Re and Rth and a compound that decreases | Re ₍₄₀₀₎ -Re ₍₇₀₀₎ | or | Rth ₍₄₀₀₎ -Rth ₍₇₀₀₎ | The transparent film according to any one of (1) to (7).
(Where Re ₍ λ ₎ is the Re value at the wavelength λnm and Rth ₍ λ ₎ is the Rth value at the wavelength λnm)
(9) The transparent film as described in (8), wherein at least one of the compounds for reducing Re and Rth has negative intrinsic birefringence.
(10) The transparent film as described in (8) or (9), wherein at least one of the compounds for reducing Re and Rth is a styrene oligomer and / or a benzyl methacrylate oligomer.
(11) The transparent film according to any one of (1) to (10), wherein the film has a thickness of 20 to 300 μm.
(12) A method for producing a transparent film according to any one of (1) to (11), wherein tenter conditions and drying are performed during production based on a retardation value obtained by an optical property measurement system in a production line. A method for producing a transparent film, comprising adjusting at least one of conditions, additive amount, and polymer type.
(13) The method for producing a transparent film according to (12), wherein the polymer is cellulose acylate, and an average degree of acetylation of cellulose acylate is adjusted during production.
(14) The transparent film production method according to (13), wherein the average degree of acetylation of cellulose acylate is adjusted by mixing at least two kinds of cellulose acylates having different degrees of acetylation.
(15) An optical compensation film having an optically anisotropic layer having Re of 0 to 200 nm and | Rth | of 0 to 400 nm on the transparent film according to any one of (1) to (11). (16) The optical compensation film as described in (15), wherein the optically anisotropic layer contains a discotic liquid crystal layer.
(17) The optical compensation film as described in (15), wherein the optically anisotropic layer contains a rod-like liquid crystal layer.
(18) The optical compensation film as set forth in (15), wherein the optically anisotropic layer contains a polymer film.
(19) At least one of the transparent film according to any one of (1) to (11) or the optical compensation film according to any one of (15) to (18) is used as a protective film for a polarizer. A characteristic polarizing plate.
(20) The polarizing plate according to (19), wherein at least one layer of a hard coat layer, an antiglare layer, an antireflection layer and an antistatic layer is provided on the surface.
(21) The transparent film according to any one of (1) to (11), the optical compensation film according to any one of (15) to (18), and the polarized light according to any one of (19) or (20) A liquid crystal display device using at least one plate.
(22) The transparent film according to any one of (1) to (11), the optical compensation film according to any one of (15) to (18), and the polarized light according to any one of (19) or (20) A VA or IPS liquid crystal display device using at least one plate.

  According to the present invention, it is possible to provide a transparent film having very small retardation in the plane and in the film thickness direction and small variations thereof. Moreover, the wide transparent film which has the said optical performance can be provided. Furthermore, an optical compensation film having a small display unevenness using the transparent film, an optical component such as a polarizing plate, and a liquid crystal display device can be provided.

  The present invention is described in detail below.

The transparent film of the present invention is characterized in that both the retardation Re (in-plane retardation value) in the plane direction of the film and the retardation Rth (thickness direction retardation value) in the film thickness direction are both small.
The in-plane retardation value Rec at the center of the transparent film of the present invention is less than 20 nm. In the use of a film having substantially no phase difference, such as a film substrate for a plastic liquid crystal display device, if the phase difference in the plane direction of the film exceeds 20 nm, a contrast failure due to light leakage caused by the phase difference in the liquid crystal display device It is easy to cause. The retardation in the plane direction of the film is more preferably 10 nm or less, and further preferably 5 nm or less. Moreover, the absolute value of the film thickness direction retardation value Rthc of the film center part of the transparent film of this invention is 20 nm or less. Rthc is preferably 10 nm or less, more preferably 5 nm or less, and still more preferably 3 nm or less.

[Re, Rth difference between film edge and center]
Re (Rec) at the center of the film and Re (R at the end of the film in the width direction of the film
ee) absolute value (| Rec−Ree |) and the absolute value (| Rthc−Rthe |) of the difference between Rth (Rthc) at the center of the film and Rth (Rthe) at the film end in the width direction of the film Measured as follows.

A strip-shaped film having a length of 3.5 cm and a film width is cut out at a right angle to the longitudinal direction of the film. A test piece having a size of 3.5 cm × 3.5 cm is cut out from the center in the width direction of the belt-like film and used for measuring the retardation in the center. Further, a 3.5 cm × 3.5 cm portion on the center side is cut out from a position 3 cm from one end of the belt-like film to obtain a test piece. That is, a portion between a position 3 cm from one extreme end in the width direction of the film and a position 6.5 cm from the extreme end is cut out and used for measuring the retardation of the end. The retardation is measured for these samples.
If the absolute value (| Rec-Ree |) of the difference between the retardation (Rec) at the center of the film and the retardation (Ree) at the end of the film is too large in the width direction of the film, or Rth (Rthc) at the center of the film ) And the Rth (Rthe) difference between the edges of the film (Rthc-Rthe |) is too large, the unevenness in the width direction of the retardation becomes large. For example, when used in a liquid crystal display device for a large screen, unevenness of contrast and color in the screen are likely to occur. In addition, it is possible to take the product from a portion of the full width where the retardation unevenness such as the center of the film is small, but in this case, the vicinity of both ends of the film cannot be used, resulting in an increase in product loss. , Yield gets worse. As a result, the product cost tends to be extremely high.
The absolute value (| Rec-Ree |) of the difference between the retardation (Rec) at the center of the film and the retardation (Ree) at the edge of the film is preferably 1.5 nm or less, more preferably 1.0 nm or less. It is. More preferably, it is 0.8 nm or less. More preferably, it is 0.5 nm or less, and particularly preferably 0.3 nm or less.
The absolute value (| Rthc−Rthe |) of the difference between Rth (Rthc) at the center of the film and Rth (Rthe) at the edge of the film is preferably 5 nm or less, more preferably 3 nm or less. More preferably, it is 1 nm or less.

[Inclination of retardation]
The inclination of retardation is measured as follows.
A strip-like film having a film width of, for example, about 3.5 cm is cut out at right angles to the longitudinal direction of the film. A portion of 3 cm is cut from one end of the strip-like film (for example, the leftmost when viewed from the feeding direction). Test pieces are cut out at intervals of 3.5 cm from the position 3 cm from the end to the center, and n pieces of test pieces having a size of 3.5 cm × 3.5 cm are obtained. Test piece numbers were set from 1 to n from the end of the film toward the center. That is, the test piece between the position of 3 cm from the endmost part of the test piece and the position of 6.5 cm from the endmost part is designated as test piece number 1, and the position of 6.5 cm from the endmost part of the test piece and the endmost part The test piece between the position of 10 cm from the part is designated as test piece number 2, and the test pieces up to the central part (test piece number n) are prepared in the same manner. The retardation of each specimen is measured. The relationship between the position xi and the obtained retardation measurement value yi is approximated to a linear function y = ax + b by the method of least squares. The coefficient “a” obtained is the inclination in the width direction of the retardation. Here, the “end portion” means a position 3 cm from the most end portion of the film. Therefore, the “distance from the film end” means the distance from the “position 3 cm from the end of the film”.
In the width direction of the film, when the absolute value of the inclination of the retardation from the film end to the center of the film in the width direction is too large, unevenness in the width direction of the retardation becomes large. For example, when used in a liquid crystal display device for a large screen, contrast unevenness is likely to occur in the screen. In addition, it is possible to take the product from a portion of the full width where the retardation unevenness such as the center of the film is small, but in this case, the vicinity of both ends of the film cannot be used, resulting in an increase in product loss. , Yield gets worse. As a result, the product cost tends to be extremely high.
The absolute value of the slope of Re from the film edge to the film center in the width direction is preferably 0.5 nm / m or less, more preferably 0.4 nm / m or less, and still more preferably 0. It is 3 nm / m or less, and particularly preferably 0.2 nm / m or less.
The absolute value of the slope of Rth from the film edge to the film center in the width direction is preferably 5 nm / m or less, more preferably 4 nm / m or less, and even more preferably 3 nm / m or less. Yes, particularly preferably 2 nm / m or less.

[Standard deviation of retardation]
The standard deviation of retardation is measured as follows.
A strip-like film having a film width is cut out at right angles to the longitudinal direction of the film. A 3 cm portion is cut from both extreme ends of the strip-shaped film. From the left end (that is, 3 cm from the leftmost end) to the opposite end (right side) (that is, 3 cm from the rightmost end) as viewed from the feeding direction, test pieces are cut out every 3.5 cm, 3 Obtain a 5 cm × 3.5 cm test piece. Here, a portion that is less than 3.5 cm on the right end as viewed from the feeding direction (that is, a portion that is less than 6.5 cm from the right end) is excised. From the left end to the right end of the film, the test piece numbers are set to 1 to n in order, and the retardation of each test piece is measured. The standard deviation in the width direction of the retardation is obtained using the measurement results thus obtained.
When the standard deviation of the retardation in the width direction is too large in the width direction of the film, the unevenness in the width direction of the retardation becomes large. For example, when used in a liquid crystal display device for a large screen, contrast unevenness is likely to occur in the screen. In addition, it is possible to take the product from a portion of the full width where the retardation unevenness such as the center of the film is small, but in this case, the vicinity of both ends of the film cannot be used, resulting in an increase in product loss. , Yield gets worse. As a result, the product cost tends to be extremely high.
The standard deviation of Re in the width direction is preferably 0.25 nm or less, more preferably 0.22 nm or less, still more preferably 0.20 nm or less, and particularly preferably 0.15 nm or less. is there. Further, the standard deviation of Rth in the width direction is preferably 2.5 nm or less, more preferably 2.0 nm or less, still more preferably 1.0 nm or less, and particularly preferably 0.5 nm. It is as follows.

[Relationship between the slow axis direction in the film plane and the film forming direction]
The relationship between the Re value and the axis is measured as follows.
A strip-like film having a film width is cut out at right angles to the longitudinal direction of the film. A 3 cm portion is cut from both extreme ends of the strip-shaped film. From the left end (that is, 3 cm from the leftmost end) to the opposite end (right side) (that is, 3 cm from the rightmost end) as viewed from the feeding direction, test pieces are cut out every 3.5 cm, 3 Obtain a 5 cm × 3.5 cm test piece. Here, a portion that is less than 3.5 cm on the right end as viewed from the feeding direction (that is, a portion that is less than 6.5 cm from the right end) is excised. From the left end portion to the right end portion of the film, the test piece numbers are 1 to n in order, and the Re and the axial angle with respect to the film forming direction of each test piece are measured. Using the measurement results thus obtained, Re in the width direction and the axial angle (θ) at that time are obtained.
The film of the present invention is a transparent film in which the retardation θ in the in-plane direction and the angle θ formed by the slow axis direction and the film forming direction in the film width direction satisfy the following formula (a7). By satisfying this equation, in-plane contrast unevenness reduction and color unevenness can be reduced when used in a liquid crystal display device.
(a7) 0.0001> sin ² (2θ) sin ² (πRe / λ)
Here, θ is an angle (radian) formed between the slow axis direction in the film plane and the film forming direction (straight direction of the film), λ is the wavelength of light (nm) in the three-dimensional refractive index measurement, π Is the pi.

[Measurement of in-plane retardation Re and thickness direction retardation Rth]
The sample was conditioned for 2 hours at 25 ° C. and 60% RH, and Re (λ) was incident on the film normal direction with light of wavelength λ nm in an automatic birefringence meter KOBRA 21ADH (manufactured by Oji Scientific Instruments). It was measured. Rth (λ) is the wavelength of λnm with Re (λ) and the in-plane slow axis or fast axis as the tilt axis, with the film normal direction set to 0 ° and the sample tilted to 50 ° every 10 °. On the basis of the retardation value measured with the incident light, an assumed average refractive index value of 1.48 and a film thickness were input and calculated. In addition, the measurement wavelength of the retardation measurement in this specification is 590 nm.

[Thickness]
The thickness of the transparent film of the present invention is preferably 20 μm to 300 μm, more preferably 30 μm to 200 μm. More preferably, it is 50 μm to 100 μm. The film thickness unevenness is preferably 5 μm or less, more preferably 3 μm or less.

[width]
The width | variety of the film of this invention can be made into arbitrary widths according to the use of the target film and the size of the manufacturing equipment of a film. The width is preferably 1000 mm or more, more preferably 1200 mm or more, still more preferably 1300 mm or more, and still more preferably 1400 mm or more. If the width is too thin, the production efficiency tends to be low, and it is difficult to apply to large liquid crystal display devices. Moreover, a width is 5000 mm or less, More preferably, it is 3000 mm or less, More preferably, it is 2400 mm or less. If the width is too wide, a large production facility is required and the cost is likely to increase.

[length]
In addition, in this specification, the longitudinal direction of a film means the direction (MD) in which a film is poured at the time of film manufacture. The width direction of the film refers to a direction (TD) perpendicular to the direction (MD) in which the film is flown during film production.
The length of the film can be any length depending on the intended use of the film and the size of the film production equipment. For example, if it is the equipment which produces the film of the fixed length of about 100 mm-5 m batchwise, it can be set as the length. Generally, continuous production equipment can be used, and the length of the film can be as long as possible within the limits of equipment such as the size of the take-up roll. Preferably, the film can be about 100 m to about 10,000 m, more preferably about 1000 m to about 5000 m, and still more preferably about 2000 m to about 3000 m. In the present specification, the retardation unevenness (variation) in the width direction of the film is mainly described, but it goes without saying that the film of the present invention is produced by such a continuous production method. Even in the length direction of a long film, the retardation is small and the unevenness is small.

[Method for producing transparent film]
The transparent film of the present invention may be formed by thermally melting a thermoplastic polymer resin, or may be formed by solution film formation (solvent casting method) from a solution in which the polymer is uniformly dissolved, It is preferable to produce a film by a solvent cast method. Hereinafter, the solvent cast method will be described.

(Film preparation method by solvent casting method)
In order to produce a transparent film using the solvent casting method, first, a solution (dope) in which a polymer of a film raw material is dissolved in an appropriate organic solvent is prepared, and this dope is applied to an appropriate support (preferably a metal support). Cast on top. Thereafter, the solvent is dried, and when the film is gelled, it is peeled off from the support, and the solvent is sufficiently dried from the film to form a transparent film.

(Metal support)
The endlessly running metal support used for producing the transparent film of the present invention includes a drum whose surface is mirror-finished by chrome plating and a stainless steel belt (band) which is mirror-finished by surface polishing. ) Is used. In order to obtain a support having a smooth surface, a material with few impurities is sufficiently polished in a clean environment in which foreign substances are excluded as much as possible to obtain a mirror surface. For example, as described in JP-A No. 2000-84960, by setting the center line average roughness Ra of the support surface to 1 to 3 nm, the film surface roughness and film haze (haze value) do not increase. I have to. The smoothness of the film formed by these solution casting film forming methods becomes better as the number of foreign matters and irregularities on the surface of the support is smaller. The casting and drying methods in the solvent casting method are described in US Pat. No. 2,336,310, US Pat. No. 2,367,603, US Pat. No. 2,429,078, US Pat. British Patent 640731, British Patent 736892, JP-B 45-4554, JP-B 49-5614, JP-A 60-176834, JP-A 60-203430, JP-A 62 No. -11,035, each publication. The dope is preferably cast on a drum or band having a surface temperature of 30 ° C. or less, and particularly preferably a metal support temperature of −40 to 40 ° C.

[Control method for variation in optical characteristics]
In order to keep the retardation variation within the target range, it is necessary to adjust the tenter conditions sequentially while measuring the retardation value with a measuring device equipped with a mechanism for measuring the retardation profile in the width direction of the film in the production line. It is preferable to sequentially adjust the temperature distribution in the drying furnace. It is also effective to adjust the amount of additives such as retardation adjusting agents and the type of polymer used. However, the adjustment of additive amount and polymer type is not enough to control the profile in the width direction, and it is more effective when combined with the tenter conditions or the temperature distribution in the drying furnace. . This method can also be used effectively for adjusting variations in film properties that occur when batches of materials are different.
The adjustment of tenter conditions and drying conditions according to the present invention will be described. The adjustment is performed both for reducing the variation in retardation in the length direction of the film and for reducing the variation in retardation in the width direction of the film.
In order to reduce the variation in retardation in the length direction of the film, always measure the retardation value at any one point in the width direction of the film in the production line, and keep it within the target range of this variation. The tenter conditions or the drying conditions are adjusted so that As conditions for adjustment, first, tenter magnification, drying average temperature and the like can be mentioned. The adjustment of the tenter magnification is not limited to be automatic or manual. Manual adjustment is preferable because it is necessary for the operator to constantly monitor the process and there is a possibility that individual differences may occur in the adjustment method. In order to adjust automatically, while measuring the retardation value of the film in the production line, for example, when the retardation is higher than the target, the stretching ratio is controlled to be small. For the control, general-purpose methods such as ON / OFF control and PI control can be used, but are not limited thereto.
In order to reduce the variation in retardation in the width direction of the film, while measuring the retardation value in the width direction of the film in the production line with high accuracy, the tenter condition or so that the variation is within the target range. Adjust the drying conditions. As conditions for adjustment, first, tenter magnification, drying average temperature and the like can be mentioned. The adjustment of the drying temperature distribution can be performed by adjusting the air volume balance, changing the set temperature, or arranging the hot air generator. The tension distribution in the drying zone can be adjusted by, for example, changing the parallelism of the rolls arranged at the entrance and exit of the tenter zone. Means for adjusting these conditions corresponding to the variation in retardation is not limited to either automatic or manual.
Furthermore, in order to keep the optical properties of the film uniform, it is preferable to adjust the addition amount of various additives and the type of polymer used. In particular, the film optical properties can be adjusted effectively by adjusting the amount of addition of a retardation adjusting agent such as a compound that lowers the optical anisotropy described later. When it is desired to reduce the retardation of the film, it is effective to increase the amount of the compound that lowers the optical anisotropy, and conversely to reduce the amount of addition when it is desired to increase the retardation of the film.
It is also preferable to adjust the polymer species used. When the polymer is cellulose acylate, the film optical properties can be adjusted effectively by adjusting the average degree of acetylation. At this time, a desired average acetylation degree can be achieved by preparing at least two types of cellulose acylate and adjusting the mixing ratio as appropriate. In order to reduce the retardation of the film, it is effective to increase the average degree of acetylation of the cellulose acylate, and conversely to reduce the average degree of acetylation in order to increase the retardation of the film.

A method for measuring the retardation value of a film in the production line according to the present invention will be described. In order to reduce the variation in retardation by the tenter magnification, the average drying temperature, etc., it is desired to always measure the retardation value of the retardation film in the production line with high accuracy. However, since the tension is applied to the film in the production line, the measured retardation value is different from the retardation value of the unloaded retardation film that is a true value. In particular, in a wide film, this difference appears remarkably due to the influence of sagging of the film. “Sagging” is a phenomenon in which when a film is held at a low tension, a portion of the film falls below the holding surface, and occurs because the length of the film differs in the width direction. When the retardation film having such a sag is conveyed in the production line, the tension acting in the width direction of the retardation film varies according to the size and shape of the sag.
For this reason, it can be solved by providing a step for adjusting and equalizing the tension around the retardation measuring section in the production line. Specifically, it is preferable to comprise a part for measuring the retardation value in the width direction of the film in the production line, and a roll with a tension adjusting function arranged around the part.
Further, in this system, in order to measure Rth, a light source and a light receiving unit are installed so as to measure in the direction of 40 degrees from the normal direction of the film.

[Material of transparent film]
As a material for forming the transparent film of the present invention, a polymer excellent in optical performance transparency, mechanical strength, thermal stability, moisture shielding property, isotropy and the like is preferable, and the above-described Re and Rth are the above-described optical performance. Any material may be used as long as it satisfies the requirements. Examples include polycarbonate polymers, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, acrylic polymers such as polymethyl methacrylate, and styrene polymers such as polystyrene and acrylonitrile / styrene copolymer (AS resin). Polyolefins such as polyethylene and polypropylene, polyolefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers, polyethersulfone polymers , Polyether ether ketone polymers, polyphenylene sulfide polymers, vinylidene chloride polymers, vinyl alcohol polymers, vinyl butyral polymers, arylate polymers, polyoxymethylene polymers, epoxy polymers, or polymers mixed with the above polymers Take an example. The transparent film of the present invention can also be formed as a cured layer of an ultraviolet-curable or thermosetting resin such as acrylic, urethane, acrylurethane, epoxy, or silicone.

  Moreover, as a material for forming the transparent film of the present invention, a thermoplastic norbornene resin can be preferably used. Examples of the thermoplastic norbornene-based resin include ZEONEX, ZEONOR manufactured by Nippon Zeon Co., Ltd., and ARTON manufactured by JSR Corporation.

  Moreover, as a material which forms the transparent film of this invention, the cellulose polymer (henceforth a cellulose acylate) conventionally used as a transparent protective film of a polarizing plate can be used preferably. A representative example of cellulose acylate is triacetyl cellulose. Details of the cellulose acylate will be described below.

[Cellulose acylate raw cotton]
Cellulose acylate raw material cellulose used in the present invention includes cotton linter and wood pulp (hardwood pulp, softwood pulp) and the like, and any cellulose acylate obtained from any raw material cellulose can be used, optionally mixed. May be. Detailed descriptions of these raw material celluloses are, for example, Plastic Materials Course (17) Fibrous resin (Maruzawa, Uda, Nikkan Kogyo Shimbun, published in 1970) and Invention Association Open Technical Report 2001-1745 (page 7). To page 8) can be used, and the cellulose acylate film of the present invention is not particularly limited.

[Substitution degree of cellulose acylate]
Next, the cellulose acylate of the present invention produced from the above-mentioned cellulose will be described. The cellulose acylate of the present invention is obtained by acylating a hydroxyl group of cellulose, and the substituent can be any acetyl group having 2 carbon atoms in the acyl group to those having 22 carbon atoms. In the cellulose acylate of the present invention, the degree of substitution of cellulose with a hydroxyl group is not particularly limited. You can get a degree. As a measuring method, it can carry out according to ASTM D-817-91.

  As described above, in the cellulose acylate of the present invention, the degree of substitution of the cellulose with a hydroxyl group is not particularly limited, but the degree of acyl substitution with the hydroxyl group of cellulose is preferably 2.50 to 3.00. Furthermore, the substitution degree is preferably 2.75 to 3.00, and more preferably 2.85 to 3.00.

  Among the acetic acid substituted for the hydroxyl group of cellulose and / or the fatty acid having 3 to 22 carbon atoms, the acyl group having 2 to 22 carbon atoms is not particularly limited and may be an aliphatic group or an allyl group. A mixture of the above may also be used. These are, for example, cellulose alkylcarbonyl esters, alkenylcarbonyl esters, aromatic carbonyl esters, aromatic alkylcarbonyl esters, and the like, each of which may further have a substituted group. These preferred acyl groups include acetyl, propionyl, butanoyl, heptanoyl, hexanoyl, octanoyl, decanoyl, dodecanoyl, tridecanoyl, tetradecanoyl, hexadecanoyl, octadecanoyl, iso-butanoyl, t-butanoyl, cyclohexanecarbonyl, Examples include oleoyl, benzoyl, naphthylcarbonyl, and cinnamoyl groups. Among these, acetyl, propionyl, butanoyl, dodecanoyl, octadecanoyl, t-butanoyl, oleoyl, benzoyl, naphthylcarbonyl, cinnamoyl and the like are preferable, and acetyl, propionyl and butanoyl are more preferable.

As a result of intensive studies by the inventor of the present invention, among the acyl substituents substituted on the above-described cellulose hydroxyl group, when the acetyl group / propionyl group / butanoyl group are composed of at least two kinds, the total substitution degree is 2 It was found that the optical anisotropy of the cellulose acylate film can be lowered in the case of .50 to 3.00. More preferred acyl substitution degree is 2.60-3.
. 00, and more preferably 2.65 to 3.00. The degree of substitution is an important parameter for film physical properties. For example, when there is lot variation in the degree of substitution due to process variations during the synthesis of cellulose acylate, two types of cellulose acylates with different degrees of substitution are prepared. It is also possible to obtain cellulose acylate having a desired substitution degree by mixing as appropriate.

[Degree of polymerization of cellulose acylate]
The degree of polymerization of cellulose acylate preferably used in the present invention is 180 to 700 in terms of viscosity average polymerization degree, and in cellulose acetate, 180 to 550 is more preferable, 180 to 400 is more preferable, and 180 to 350 is particularly preferable. . If the degree of polymerization is too high, the viscosity of the cellulose acylate dope solution becomes high, and film production becomes difficult due to casting. If the degree of polymerization is too low, the strength of the produced film will decrease. The average degree of polymerization can be measured by Uda et al.'S intrinsic viscosity method (Kazuo Uda, Hideo Saito, Journal of Textile Society, Vol. This is described in detail in JP-A-9-95538.
Further, the molecular weight distribution of cellulose acylate preferably used in the present invention is evaluated by gel permeation chromatography, and its polydispersity index Mw / Mn (Mw is mass average molecular weight, Mn is number average molecular weight) is small, and molecular weight distribution. Is preferably narrow. The specific value of Mw / Mn is preferably 2.0 to 4.0, more preferably 2.0 to 3.5, and most preferably 2.3 to 3.3. preferable.

  When the low molecular component is removed, the average molecular weight (degree of polymerization) increases, but the viscosity becomes lower than that of normal cellulose acylate, which is useful. Cellulose acylate having a small amount of low molecular components can be obtained by removing low molecular components from cellulose acylate synthesized by a usual method. The removal of the low molecular component can be carried out by washing the cellulose acylate with an appropriate organic solvent. In addition, when manufacturing a cellulose acylate with few low molecular components, it is preferable to adjust the sulfuric acid catalyst amount in an acetylation reaction to 0.5-25 mass parts with respect to 100 mass parts of cellulose. When the amount of the sulfuric acid catalyst is within the above range, cellulose acylate that is preferable in terms of molecular weight distribution (uniform molecular weight distribution) can be synthesized. When used in the production of the cellulose acylate of the present invention, its moisture content is preferably 2% by mass or less, more preferably 1% by mass or less, and particularly 0.7% by mass or less. It is a cellulose acylate having a rate. In general, cellulose acylate contains water and is known to be 2.5 to 5% by mass. In order to obtain the moisture content of the cellulose acylate in the present invention, it is necessary to dry, and the method is not particularly limited as long as the desired moisture content is obtained. These cellulose acylates of the present invention are described in detail on page 7 to page 12 of the raw material cotton and the synthesis method in the Japan Society for Invention and Technology (public technical number 2001-1745, published on March 15, 2001, Japan Society for Invention). It is described in.

[Residual sulfuric acid content]
The residual sulfuric acid content (as sulfur element content) in the cellulose acylate film can be measured by ASTM-D817-96. In the present invention, it is preferable to use cellulose acylate having a high acetylation degree from the viewpoint of sufficiently reducing the optical anisotropy while minimizing the addition amount of the optical anisotropy reducing agent of the film. When the acetylation degree of acylate is increased, the residual sulfuric acid content in the film tends to decrease. When the total amount of sulfuric acid in the cellulose acylate is reduced, the peeling resistance when peeling the cellulose acylate solution dope from the metal band is increased, and the peeling resistance is increased, so the cellulose acylate film is peeled when peeling. May be stretched in the longitudinal direction, and the polymer film may be oriented slightly but the front retardation may increase. In particular, when the amount of residual sulfuric acid is 25 ppm or less, the peeling resistance when peeling the cast film from the metal band is remarkably increased, and the front retardation tends to deteriorate. In the present invention, the above problem can be solved by using cellulose acylate having a residual sulfuric acid amount of 100 ppm or more, or using a release agent such as citrate ester in combination. “Ppm” used in the present specification is conventionally used in the art as described above, and is a mass-based value for cellulose acylate film, and is equivalent to “mg · kg”. .

[Alkaline earth metal content]
The alkaline earth metal content in the cellulose acylate film is the total content of Ca and Mg. Here, the alkaline earth metal atom content is determined using an X-ray photoelectron spectrometer (XPS). Can be measured. The smaller the amount of alkaline earth metal (especially Ca), the lower the peeling resistance, and the front retardation Re can be further reduced. In the present invention, the preferable range of the alkaline earth metal is 0 to 60 ppm, more preferably 0 to 40 ppm, and still more preferably 1 to 20 ppm. If it exceeds 70 ppm, the peeling resistance is deteriorated and the front retardation Re is increased, which is not preferable. The content of the alkaline earth metal of the present invention is calculated using a cellulose acylate film sample. The content of alkaline earth metal in the film can be adjusted by adjusting the content of alkaline earth metal in cellulose acylate which is a raw material.

  The cellulose ester of the present invention is also affected by trace metal components. These are thought to be related to water used in the manufacturing process, but it is preferable that there are few components that can form insoluble nuclei, and they may contain organic acidic groups such as iron, calcium, and magnesium. It is preferable that the amount of metal ions that form an unnecessary substance by forming a salt with a polymer decomposition product or the like is small. In practice, however, the interaction between the components and other factors are also somewhat related, so it is not simply necessary to have a small amount.

The iron (Fe) component is preferably 3 ppm or less, more preferably 2 ppm or less, and most preferably 1 ppm. Similarly, it is preferable that the amount of cotton linter or wood pulp used is small.
“Ppm” used in the present specification is conventionally used in the art as described above, and is a mass-based value for cellulose acylate film, and is equivalent to “mg · kg”. .

  About calcium (Ca) component, it is contained in a lot of ground water and river water, etc., and it becomes hard water, and it is not suitable as drinking water, but with carboxylic acid and acidic components such as sulfonic acid, Ligand and coordination compounds, that is, complexes are easily formed, and many unnecessary calcium-derived scum (insoluble starch, turbidity) is formed.

The calcium (Ca) component is preferably as small as possible in practice, but the optimum value differs between when cotton linter is used and when wood pulp is used.
“Ppm” used in the present specification is conventionally used in the art as described above, and is a mass-based value for cellulose acylate film, and is equivalent to “mg · kg”. .

  The magnesium (Mg) component is also abundantly contained in the groundwater as in the case of calcium, and also causes unnecessary substances. If too much of these magnesium components are formed, insoluble matter is generated. However, if the amount is too small, the characteristics are not good.

  The cellulose acylate of the present invention can be used as a single group or a mixture of two or more different types of cellulose acylates as long as the substituent, substitution degree, polymerization degree, molecular weight distribution and the like are within the above-mentioned ranges.

[Additive]
The transparent film of the present invention has various additives depending on the application in each preparation step (for example, a compound that reduces optical anisotropy, a wavelength dispersion adjusting agent, an ultraviolet ray inhibitor, a plasticizer, a deterioration inhibitor, and fine particles. , And the like, which will be described below. Further, the addition may be performed at any time in the dope preparation process, but may be performed by adding an additive to the final preparation process of the dope preparation process.
It is preferable to contain at least one compound that reduces the optical anisotropy of the transparent film of the present invention, particularly the retardation Rth in the film thickness direction, within the range satisfying the following formulas (I) and (II).
(I) (Rth (A) −Rth (0)) / A ≦ −1.0
(II) 0.01 ≦ A ≦ 30
The above formulas (I) and (II) are: (I) (Rth (A) −Rth (0)) / A ≦ −2.0
(II) 0.05 ≦ A ≦ 25
It is more desirable to be
(I) (Rth (A) −Rth (0)) / A ≦ −3.0
(II) 0.1 ≦ A ≦ 20
It is even more desirable.
Here, Rth (A) is Rth (nm) of a film containing A% of a compound that lowers Rth, Rth (0) is Rth (nm) of a film not containing a compound that lowers Rth, and A is a film raw polymer. It is the weight (%) of the compound when the weight of is 100.

[Structural characteristics of compounds that reduce the optical anisotropy of transparent films]
The compound which reduces the optical anisotropy of a transparent film is demonstrated. As a result of intensive studies, the inventors of the present invention have sufficiently reduced the optical anisotropy using a compound that suppresses the in-plane and film thickness orientation of the polymer in the film, and the Re is zero. Rth was made close to zero. For this purpose, it is advantageous that the compound that lowers the optical anisotropy is sufficiently compatible with the polymer component, and the compound itself does not have a rod-like structure or a planar structure. Specifically, when a plurality of planar functional groups such as aromatic groups are provided, a structure having these functional groups in a non-planar rather than the same plane is advantageous.

(Log P value)
In producing the transparent film of the present invention, when a hydrophilic polymer such as cellulose acylate is used, the polymer in the film is prevented from being oriented in the plane and in the film thickness direction as described above. Of the compounds that reduce optical anisotropy, compounds having an octanol-water partition coefficient (log P value) of 0 to 7 are preferred. A compound having a log P value of more than 7 has poor compatibility with the hydrophilic polymer, and tends to cause cloudiness or powder blowing of the film. In addition, since the compound having a log P value smaller than 0 has high hydrophilicity, the water resistance of the transparent film may be deteriorated. A more preferable range of the logP value is 1 to 6, and a particularly preferable range is 1.5 to 5.
The octanol-water partition coefficient (log P value) can be measured by a flask immersion method described in JIS Japanese Industrial Standard Z7260-107 (2000). Further, the octanol-water partition coefficient (log P value) can be estimated by a computational chemical method or an empirical method instead of the actual measurement. As a calculation method, Crippen's fragmentation method (J. Chem. Inf. Comput. Sci., 27, 21 (1987).), Viswanadhan's fragmentation method (J. Chem. Inf. Comput. Sci., 29, 163 (1989).) Broto's fragmentation method (Eur. J. Med. Chem.- Chim. Theor., 19, 71 (1984).) And the like are preferably used, but Crippen's fragmentation method (J. Chem. Inf. Comput. Sci., 27 , 21 (1987). When the log P value of a certain compound varies depending on the measurement method or calculation method, it is preferable to determine whether or not the compound is within the scope of the present invention by the Crippen's fragmentation method.

[Physical properties of compounds that reduce optical anisotropy]
The compound that reduces optical anisotropy may or may not contain an aromatic group. The compound that reduces the optical anisotropy preferably has a molecular weight of 150 or more and 3000 or less, preferably 170 or more and 2000 or less, and particularly preferably 200 or more and 1000 or less. A specific monomer structure may be used as long as these molecular weights are within the range, and an oligomer structure or a polymer structure in which a plurality of the monomer units are bonded may be used.
It is also effective to use a compound having negative intrinsic birefringence as the compound that lowers the optical anisotropy. For example, examples of the organic compound include styrene oligomer, polystyrene, benzyl methacrylate oligomer, acrylic resin, and examples of the inorganic compound include strontium carbonate.
The compound that reduces optical anisotropy is preferably a liquid at 25 ° C. or a solid having a melting point of 25 to 250 ° C., more preferably a liquid at 25 ° C. or a melting point of 25 to 200 ° C. It is a solid. Moreover, it is preferable that the compound which reduces optical anisotropy does not volatilize in the process of dope casting of transparent film preparation, and drying.
The amount of the compound that decreases the optical anisotropy is preferably 0.01 to 30% by mass, more preferably 1 to 25% by mass, and more preferably 5 to 20% by mass of the polymer component. Particularly preferred.
The compound that decreases the optical anisotropy may be used alone, or two or more compounds may be mixed and used in an arbitrary ratio.
The timing for adding the compound for reducing the optical anisotropy may be any time during the dope preparation process, or may be performed at the end of the dope preparation process.

In the compound that reduces the optical anisotropy, the average content of the compound in the portion from the surface on at least one side to 10% of the total film thickness is 80- of the average content of the compound in the central portion of the transparent film. 99% is preferred. The abundance of the compound of the present invention can be determined, for example, by measuring the amount of the compound at the surface and in the center by the method using an infrared absorption spectrum described in JP-A-8-57879.
Specific examples of the compound that lowers the optical anisotropy of the transparent film preferably used in the present invention include compounds represented by any one of the following general formulas (13), (18), and (19). However, the present invention is not limited to these compounds.

[In General Formula (13), R ¹ represents an alkyl group or an aryl group, and R ² and R ³ each independently represent a hydrogen atom, an alkyl group, or an aryl group. However, the number of carbon atoms of R ¹ , R ² and R ³ is 10 or more. ]

[In General Formula (18), R ¹ represents an alkyl group or an aryl group, and R ² and R ³ each independently represent a hydrogen atom, an alkyl group, or an aryl group. ]

[In the general formula (19), R ⁴ , R ⁵ and R ⁶ each independently represents an alkyl group or an aryl group. ]

The compound of the general formula (13) will be described.
In the general formula (13), R ¹ represents an alkyl group or an aryl group, and R ² and R ³ each independently represent a hydrogen atom, an alkyl group, or an aryl group. Further, the total number of carbon atoms of R ¹ , R ² and R ³ is particularly preferably 10 or more. R ¹ , R ² and R ³ may be substituted, and the substituent is preferably a fluorine atom, an alkyl group, an aryl group, an alkoxy group, a sulfone group and a sulfonamide group, and an alkyl group, an aryl group, an alkoxy group, A sulfone group and a sulfonamide group are particularly preferred. Further, the alkyl group may be linear, branched or cyclic, and preferably has 1 to 25 carbon atoms, more preferably 6 to 25, and more preferably 6 to 20 (E.g., methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, amyl, isoamyl, t-amyl, hexyl, cyclohexyl, heptyl, octyl, bicyclooctyl, nonyl, adamantyl, decyl, t-octyl, undecyl, Dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, didecyl) are particularly preferred. As the aryl group, those having 6 to 30 carbon atoms are preferable, and those having 6 to 24 carbon atoms (for example, phenyl, biphenyl, terphenyl, naphthyl, binaphthyl, triphenylphenyl) are particularly preferable. Preferred examples of the compound represented by the general formula (13) are shown below, but the present invention is not limited to these specific examples.

  Although the preferable example of a compound represented by General formula (18) or General formula (19) below is shown below, this invention is not limited to these specific examples. In the compound represented by the general formula (18) or the general formula (19), specific examples of the alkyl group and the aryl group are the same as those in the general formula (13).

In the formula, Pr ¹ represents an isopropyl group.

[Wavelength dispersion modifier]
A compound for reducing the wavelength dispersion of the transparent film (hereinafter also referred to as a wavelength dispersion adjusting agent) will be described. In order to improve the Rth wavelength dispersion of the transparent film of the present invention, a compound that reduces the Rth wavelength dispersion ΔRth = | Rth ₍₄₀₀₎ −Rth ₍₇₀₀₎ | represented by the following formula (III): It is preferable to contain at least one of the following formulas (IV) and (V).
(III) ΔRth = | Rth ₍₄₀₀₎ −Rth ₍₇₀₀₎ |
(IV) (ΔRth (B) −ΔRth (0)) / B ≦ −2.0
(V) 0.01 ≦ B ≦ 30
The above formulas (IV) and (V) are: (IV) (ΔRth (B) −ΔRth (0)) / B ≦ −3.0
(V) 0.05 ≦ B ≦ 25
It is more desirable to be
(IV) (ΔRth (B) −ΔRth (0)) / B ≦ −4.0
(V) 0.1 ≦ B ≦ 20
It is even more desirable.
Here, ΔRth (B) is ΔRth (nm) of the film containing B mass% of the wavelength dispersion adjusting agent, ΔRth (0) is ΔRth (nm) of the film not containing the wavelength dispersion adjusting agent, and B is the film raw polymer. This is the mass (%) of the wavelength dispersion adjusting agent when the mass is 100.
The above-mentioned wavelength dispersion adjusting agent has at least a compound having absorption in the ultraviolet region of 200 to ₄₀₀ nm and reducing | Re ₍₄₀₀₎ -Re ₍₇₀₀₎ | and | Rth ₍₄₀₀₎ -Rth ₍₇₀₀₎ | The wavelength dispersion of Re and Rth of the cellulose acylate film was adjusted by including 0.01 to 30% by weight of one type, cellulose acylate solid content.

  In general, the Re and Rth values of various polymer films have wavelength dispersion characteristics that are larger on the long wavelength side than on the short wavelength side. Therefore, in the case of a polymer film having such wavelength dispersion characteristics (for example, a cellulose acylate film), it is required to smooth the wavelength dispersion by increasing Re and Rth on the relatively short short wavelength side. . On the other hand, a compound having absorption in the ultraviolet region of 200 to 400 nm has a wavelength dispersion characteristic in which the absorbance on the short wavelength side is larger than that on the long wavelength side. If the compound itself is isotropically present inside the transparent film, it is assumed that the birefringence of the compound itself, and thus the wavelength dispersion of Re and Rth, is larger on the short wavelength side as the wavelength dispersion of absorbance.

  Therefore, by using the compound having absorption in the ultraviolet region of 200 to 400 nm as described above and assuming that the wavelength dispersion of Re and Rth of the compound itself is large on the short wavelength side, the long wavelength side has a large wavelength dispersion characteristic. The wavelength dispersion of Re and Rth of the polymer film can be prepared. For this purpose, the compound for adjusting the wavelength dispersion is required to be sufficiently uniformly compatible with the polymer component. The absorption band range in the ultraviolet region of such a compound is preferably 200 to 400 nm, more preferably 220 to 395 nm, and even more preferably 240 to 390 nm.

In recent years, liquid crystal display devices such as televisions, notebook personal computers, and mobile portable terminals have been required to have excellent transmittance of optical members used in liquid crystal display devices in order to increase luminance with less power. In that respect, a compound having absorption in the ultraviolet region of 200 to ₄₀₀ nm and reducing | Re ₍₄₀₀₎ −Re ₍₇₀₀₎ | and | Rth ₍₄₀₀₎ −Rth ₍₇₀₀₎ | In that case, the spectral transmittance is required to be excellent. In the transparent film of the present invention, the spectral transmittance at a wavelength of 380 nm is preferably 45% or more and 95% or less, and the spectral transmittance at a wavelength of 350 nm is preferably 10% or less.

  As described above, the wavelength dispersion adjusting agent preferably used in the present invention preferably has a molecular weight of 250 to 1000 from the viewpoint of volatility. More preferably, it is 260-800, More preferably, it is 270-800, Most preferably, it is 300-800. A specific monomer structure may be used as long as these molecular weights are within the range, and an oligomer structure or a polymer structure in which a plurality of the monomer units are bonded may be used.

  It is preferable that the wavelength dispersion adjusting agent is not volatilized in the process of dope casting for transparent film production and drying.

(Compound addition amount)
The addition amount of the chromatic dispersion adjusting agent preferably used in the present invention is preferably 0.01 to 30% by weight, more preferably 0.1 to 20% by weight of the polymer component, and 0.2 It is particularly preferably 10 to 10% by weight.

(Method of compound addition)
These wavelength dispersion adjusting agents may be used alone or in combination of two or more compounds at an arbitrary ratio.
Further, the timing of adding these wavelength dispersion adjusting agents may be any time during the dope preparation process, or may be performed at the end of the dope preparation process.

  Specific examples of the wavelength dispersion adjusting agent preferably used in the present invention include, for example, benzotriazole compounds, benzophenone compounds, cyano group-containing compounds, oxybenzophenone compounds, salicylic acid ester compounds, nickel complex compounds, and the like. However, the present invention is not limited to these compounds.

  As the benzotriazole-based compound, those represented by the general formula (101) are preferably used as the wavelength dispersion adjusting agent of the present invention.

Formula (101) Q ¹ -Q ² -OH

(In the formula, Q ¹ represents a nitrogen-containing aromatic heterocyclic group, and Q ² represents an aromatic cyclic group.)

Q ¹ represents a nitrogen-containing aromatic heterocyclic group, preferably a 5- to 7-membered nitrogen-containing aromatic heterocyclic group, more preferably a 5- to 6-membered nitrogen-containing aromatic heterocyclic group, Imidazole, pyrazole, triazole, tetrazole, thiazole, oxazole, selenazole, benzotriazole, benzothiazole, benzoxazole, benzoselenazole, thiadiazole, oxadiazole, naphthothiazole, naphthoxazole, azabenzimidazole, purine, pyridine, pyrazine, Examples of the ring group include pyrimidine, pyridazine, triazine, triazaindene, and tetrazaindene, and more preferably a 5-membered nitrogen-containing aromatic heterocycle or a triazine ring, specifically, imidazole, pyrazole, Triazole Each ring such as tetrazole, thiazole, oxazole, benzotriazole, benzothiazole, benzoxazole, thiadiazole, oxadiazole, 1,3,5-triazine is preferable, and benzotriazole ring or 1,3,5-triazine is particularly preferable. It is a ring.
The nitrogen-containing aromatic heterocycle represented by Q ¹ may further have a substituent, and the substituent T described below can be applied as the substituent. In addition, when there are a plurality of substituents, each may be condensed to form a ring.

The aromatic ring represented by Q ² may be an aromatic hydrocarbon ring or an aromatic heterocycle. These may be monocyclic or may form a condensed ring with another ring.
The aromatic hydrocarbon ring is preferably (preferably a monocyclic or bicyclic aromatic hydrocarbon ring having 6 to 30 carbon atoms (for example, benzene ring, naphthalene ring etc.), more preferably 6 carbon atoms. An aromatic hydrocarbon ring having 20 to 20 carbon atoms, more preferably an aromatic hydrocarbon ring having 6 to 12 carbon atoms.), More preferably a benzene ring.
The aromatic heterocycle is preferably an aromatic heterocycle containing a nitrogen atom or a sulfur atom. Specific examples of the heterocyclic ring include, for example, thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiazoline, thiazole, thiadiazole, oxazoline, oxazole, oxadiazole, quinoline, isoquinoline, Examples include phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzthiazole, benzotriazole, and tetrazaindene. The aromatic hetero ring is preferably a pyridine ring, a triazine ring or a quinoline ring.

The aromatic ring group represented by Q ² is preferably an aromatic hydrocarbon ring group, more preferably a naphthalene ring group or a benzene ring group, and particularly preferably a benzene ring group. Q ² may further have a substituent, and the substituent T described later is preferable.

Examples of the substituent T include an alkyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, such as methyl, ethyl, iso-propyl, tert-butyl. , N-octyl, n-decyl, n-hexadecyl, cyclopropyl, cyclopentyl, cyclohexyl, etc.), an alkenyl group (preferably having 2-20 carbon atoms, more preferably 2-12 carbon atoms, especially Preferably it is C2-C8, for example, each group, such as vinyl, allyl, 2-butenyl, 3-pentenyl, etc.), an alkynyl group (preferably C2-C20, more preferably C2-C2). 12, particularly preferably 2 to 8 carbon atoms, and examples thereof include groups such as propargyl and 3-pentynyl), aryl groups (preferably 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, and particularly preferably 6 to 12 carbon atoms, and examples thereof include phenyl, p-methylphenyl, naphthyl, and the like. A substituted amino group (preferably having 0 to 20 carbon atoms, more preferably 0 to 10 carbon atoms, and particularly preferably 0 to 6 carbon atoms; for example, amino, methylamino, dimethylamino, diethylamino, dibenzylamino, etc. Group), an alkoxy group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, and examples thereof include methoxy, ethoxy, and butoxy groups. An aryloxy group (preferably having 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, and particularly preferably 6 to 12 carbon atoms). Ruoxy, 2-naphthyloxy groups, etc.), acyl groups (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms such as acetyl, Benzoyl, formyl, pivaloyl, etc.), alkoxycarbonyl groups (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as methoxycarbonyl, ethoxycarbonyl, etc. And aryloxycarbonyl groups (preferably having 7 to 20 carbon atoms, more preferably 7 to 16 carbon atoms, and particularly preferably 7 to 10 carbon atoms, such as a phenyloxycarbonyl group). An acyloxy group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, especially Preferably it is C2-C10, for example, an acetoxy group, a benzoyloxy group, etc. are mentioned. ),

An acylamino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 10 carbon atoms, and examples thereof include an acetylamino group and a benzoylamino group), an alkoxycarbonylamino group. (Preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, and particularly preferably 2 to 12 carbon atoms, such as methoxycarbonylamino group), aryloxycarbonylamino group (preferably carbon 7 to 20, more preferably 7 to 16 carbon atoms, particularly preferably 7 to 12 carbon atoms, such as a phenyloxycarbonylamino group), a sulfonylamino group (preferably 1 to 20 carbon atoms, More preferably, it has 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms. And groups such as amino and benzenesulfonylamino), sulfamoyl groups (preferably having 0 to 20 carbon atoms, more preferably 0 to 16 carbon atoms, particularly preferably 0 to 12 carbon atoms, such as sulfamoyl, methyl And each group such as sulfamoyl, dimethylsulfamoyl, phenylsulfamoyl, etc.), a carbamoyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to carbon atoms). 12 and examples thereof include carbamoyl, methylcarbamoyl, diethylcarbamoyl, phenylcarbamoyl and the like.

An alkylthio group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methylthio and ethylthio groups), an arylthio group (preferably having a carbon number) 6 to 20, more preferably 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenylthio, and the like, and a sulfonyl group (preferably 1 to 20 carbon atoms, more preferably 1 carbon atom). To 16, particularly preferably 1 to 12 carbon atoms, such as mesyl, tosyl, etc.), sulfinyl groups (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably carbon numbers). 1 to 12, for example, methanesulfinyl group, benzenesulfinyl group, etc.), ureido group (preferably having 1 carbon atom) 20, More preferably, it is C1-C16, Most preferably, it is C1-C12, for example, each group, such as a ureido, methylureido, a phenylureido, etc.), phosphoric acid amide group (preferably C1) -20, more preferably 1-16 carbon atoms, particularly preferably 1-12 carbon atoms, and examples thereof include diethylphosphoric acid amide and phenylphosphoric acid amide groups), hydroxy groups, mercapto groups, halogen atoms (For example, fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxyl group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group, heterocyclic group (preferably having a carbon number of 1 to 30 and more preferably 1 to 12. Examples of the hetero atom include a nitrogen atom, an oxygen atom, and a sulfur atom, specifically, And each group such as imidazolyl, pyridyl, quinolyl, furyl, piperidyl, morpholino, benzoxazolyl, benzimidazolyl, benzthiazolyl), silyl group (preferably having 3 to 40 carbon atoms, more preferably 3 to 3 carbon atoms). 30 and particularly preferably 3 to 24 carbon atoms, and examples thereof include a trimethylsilyl group and a triphenylsilyl group).
These substituents may be further substituted. Moreover, when there are two or more substituents, they may be the same or different. If possible, they may be linked together to form a ring.

As the general formula (101), a compound represented by the following general formula (101-A) is preferable.
General formula (101-A)

(Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , and R ⁸ each independently represents a hydrogen atom or a substituent)

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , and R ⁹ each independently represent a hydrogen atom or a substituent. Applicable. These substituents may be further substituted with another substituent, and the substituents may be condensed to form a ring structure.
R ¹ and R ³ are preferably hydrogen atoms, alkyl groups, alkenyl groups, alkynyl groups, aryl groups, substituted or unsubstituted amino groups, alkoxy groups, aryloxy groups, hydroxy groups, and halogen atoms, more preferably hydrogen atoms. An atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group and a halogen atom, more preferably a hydrogen atom and an alkyl group having 1 to 12 carbon atoms, particularly preferably an alkyl group having 1 to 12 carbon atoms (preferably 4 to 12 carbon atoms).

R ² and R ⁴ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, and a halogen atom, more preferably A hydrogen atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group, and a halogen atom, more preferably a hydrogen atom and an alkyl group having 1 to 12 carbon atoms, particularly preferably a hydrogen atom and a methyl group, most preferably Is a hydrogen atom.

R ⁵ and R ⁸ are preferably hydrogen atoms, alkyl groups, alkenyl groups, alkynyl groups, aryl groups, substituted or unsubstituted amino groups, alkoxy groups, aryloxy groups, hydroxy groups, and halogen atoms, more preferably hydrogen atoms. An atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group, and a halogen atom, more preferably a hydrogen atom and an alkyl group having 1 to 12 carbon atoms, particularly preferably a hydrogen atom and a methyl group, most preferably It is a hydrogen atom.

R ⁶ and R ⁷ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, and a halogen atom, more preferably a hydrogen atom. An atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group, and a halogen atom, more preferably a hydrogen atom and a halogen atom, and particularly preferably a hydrogen atom and a chlorine atom.

More preferable as the general formula (101) is a compound represented by the following general formula (101-B).
General formula (101-B)

(In formula, R < ¹ >, R < ³ >, R < ⁶ > and R < ⁷ > are synonymous with those in general formula (101-A), and their preferred ranges are also the same.)

  Specific examples of the compound represented by formula (101) are listed below, but the present invention is not limited to the following specific examples.

  Among the benzotriazole compounds listed above, when the transparent film of the present invention was produced without including those having a molecular weight of 320 or less, it was confirmed that it was advantageous in terms of retention.

In addition, as the benzophenone compound which is one of the wavelength dispersion adjusting agents used in the present invention, those represented by the general formula (102) are preferably used.
Formula (102)

(In the formula, Q ¹ and Q ² each independently represent an aromatic ring. X represents NR (R represents a hydrogen atom or a substituent), an oxygen atom or a sulfur atom.)

The aromatic ring represented by Q ¹ and Q ² may be an aromatic hydrocarbon ring or an aromatic heterocycle. These may be monocyclic or may form a condensed ring with another ring.
The aromatic hydrocarbon ring represented by Q ¹ and Q ² is preferably (preferably a monocyclic or bicyclic aromatic hydrocarbon ring having 6 to 30 carbon atoms (for example, a benzene ring, a naphthalene ring, etc.). More preferably an aromatic hydrocarbon ring having 6 to 20 carbon atoms, still more preferably an aromatic hydrocarbon ring having 6 to 12 carbon atoms.) More preferably, it is a benzene ring.
The aromatic heterocyclic group represented by Q ¹ and Q ² is preferably an aromatic heterocyclic group containing at least one of an oxygen atom, a nitrogen atom or a sulfur atom. Specific examples of the heterocyclic ring include, for example, furan, pyrrole, thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiazoline, thiazole, thiadiazole, oxazoline, oxazole, oxadiazole, Examples include quinoline, isoquinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzothiazole, benzotriazole, and tetrazaindene. As the aromatic hetero ring, a pyridine ring, a triazine ring and a quinoline ring are preferable.
The aromatic ring group represented by Q ¹ and Q ² is preferably an aromatic hydrocarbon ring, more preferably an aromatic hydrocarbon ring having 6 to 10 carbon atoms, still more preferably a substituted or unsubstituted benzene ring. It is.
Q ¹ and Q ² may further have a substituent, and the substituent T is preferable, but the substituent does not contain a carboxylic acid group, a sulfonic acid group, or a quaternary ammonium group. Further, if possible, substituents may be linked to form a ring structure.

  X represents NR (R represents a hydrogen atom or a substituent. Substituent T described later can be applied as the substituent), an oxygen atom or a sulfur atom, and X is preferably NR (R is preferably an acyl group) A sulfonyl group, and these substituents may be further substituted.) Or an oxygen atom, particularly preferably an oxygen atom.

  The substituent T is synonymous with that of the general formula (101).

As the general formula (102), a compound represented by the following general formula (102-A) is preferable.
Formula (102-A)

(In the formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , and R ⁹ each independently represents a hydrogen atom or a substituent.)

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , and R ⁹ each independently represent a hydrogen atom or a substituent, and the above-mentioned substituent T is applied as the substituent. it can. These substituents may be further substituted with another substituent, and the substituents may be condensed to form a ring structure.

R ¹ , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁸ and R ⁹ are preferably a hydrogen atom, alkyl group, alkenyl group, alkynyl group, aryl group, substituted or unsubstituted amino group, alkoxy group, aryl An oxy group, a hydroxy group and a halogen atom, more preferably a hydrogen atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group and a halogen atom, still more preferably a hydrogen atom and a carbon 1-12 alkyl group. Particularly preferred are a hydrogen atom and a methyl group, and most preferred is a hydrogen atom.

R ² is preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, a halogen atom, more preferably a hydrogen atom or one carbon atom. An alkyl group having -20 carbon atoms, an amino group having 0-20 carbon atoms, an alkoxy group having 1-12 carbon atoms, an aryloxy group having 6-12 carbon atoms, and a hydroxy group, and more preferably an alkoxy group having 1-20 carbon atoms. And particularly preferably an alkoxy group having 1 to 12 carbon atoms.

R ⁷ is preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, a halogen atom, more preferably a hydrogen atom or one carbon atom. An alkyl group having -20 carbon atoms, an amino group having 0-20 carbon atoms, an alkoxy group having 1-12 carbon atoms, an aryloxy group having 6-12 carbon atoms, and a hydroxy group, more preferably a hydrogen atom, having 1-20 carbon atoms. An alkyl group (preferably having 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, still more preferably a methyl group), particularly preferably a methyl group or a hydrogen atom.

More preferable as the general formula (102) is a compound represented by the following general formula (102-B).
General formula (102-B)

(Wherein R ¹⁰ represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, or a substituted or unsubstituted aryl group.)

R ¹⁰ represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, or a substituted or unsubstituted aryl group. Applicable.
R ¹⁰ is preferably a substituted or unsubstituted alkyl group, more preferably a substituted or unsubstituted alkyl group having 5 to 20 carbon atoms, and still more preferably a substituted or unsubstituted alkyl group having 5 to 12 carbon atoms. (Including n-hexyl group, 2-ethylhexyl group, n-octyl group, n-decyl group, n-dodecyl group, benzyl group, etc.), particularly preferably a substitution of 6 to 12 carbon atoms or An unsubstituted alkyl group (2-ethylhexyl group, n-octyl group, n-decyl group, n-dodecyl group, benzyl group).

The compound represented by the general formula (102) can be synthesized by a known method described in JP-A-11-12219.
Specific examples of the compound represented by the general formula (102) are given below, but the present invention is not limited to the following specific examples.

As the compound containing a cyano group, which is one of the wavelength dispersion adjusting agents used in the present invention, those represented by the general formula (103) are preferably used.
General formula (103)

(In the formula, Q ¹ and Q ² each independently represents an aromatic ring. X ¹ and X ² represent a hydrogen atom or a substituent, and at least one of them represents a cyano group.)
The aromatic ring represented by Q ¹ and Q ² may be an aromatic hydrocarbon ring or an aromatic heterocycle. These may be monocyclic or may form a condensed ring with another ring.

The aromatic hydrocarbon ring is preferably (preferably a monocyclic or bicyclic aromatic hydrocarbon ring having 6 to 30 carbon atoms (for example, benzene ring, naphthalene ring etc.), more preferably 6 carbon atoms. An aromatic hydrocarbon ring having 20 to 20 carbon atoms, more preferably an aromatic hydrocarbon ring having 6 to 12 carbon atoms.), More preferably a benzene ring.

  The aromatic heterocycle is preferably an aromatic heterocycle containing a nitrogen atom or a sulfur atom. Specific examples of the heterocyclic ring include, for example, thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiazoline, thiazole, thiadiazole, oxazoline, oxazole, oxadiazole, quinoline, isoquinoline, Examples include phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzthiazole, benzotriazole, and tetrazaindene. As the aromatic hetero ring, a pyridine ring, a triazine ring and a quinoline ring are preferable.

The aromatic ring represented by Q ¹ and Q ² is preferably an aromatic hydrocarbon ring, and more preferably a benzene ring.
Q ¹ and Q ² may further have a substituent, and the substituent T is preferred. The substituent T is synonymous with that of the general formula (101).

X ¹ and X ² each represent a hydrogen atom or a substituent, and at least one of them represents a cyano group. The substituent T described above can be applied to the substituents represented by X ¹ and X ² . The substituents represented by X ¹ and X ² may be further substituted with other substituents, and X ¹ and X ² may be condensed to form a ring structure.

X ¹ and X ² are preferably a hydrogen atom, an alkyl group, an aryl group, a cyano group, a nitro group, a carbonyl group, a sulfonyl group, or an aromatic heterocycle, and more preferably a cyano group, a carbonyl group, a sulfonyl group, An aromatic heterocycle, more preferably a cyano group or a carbonyl group, and particularly preferably a cyano group or an alkoxycarbonyl group (—C (═O) OR (R is an alkyl group having 1 to 20 carbon atoms, 6 carbon atoms). ~ 12 aryl groups and combinations thereof.

Preferred as the general formula (103) is a compound represented by the following general formula (103-A).
General formula (103-A)

(Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ each independently represents a hydrogen atom or a substituent. X ¹ and X ² Are the same as those in formula (103), and the preferred range is also the same.)

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ each independently represent a hydrogen atom or a substituent, and examples of the substituent include the substituents described above. T is applicable. These substituents may be further substituted with another substituent, and the substituents may be condensed to form a ring structure.

R ¹ , R ² , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁹ , and R ¹⁰ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, An alkoxy group, an aryloxy group, a hydroxy group, and a halogen atom, more preferably a hydrogen atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group, and a halogen atom, still more preferably a hydrogen atom and carbon 1-12. An alkyl group, particularly preferably a hydrogen atom or a methyl group, and most preferably a hydrogen atom.

R ³ and R ⁸ are preferably hydrogen atoms, alkyl groups, alkenyl groups, alkynyl groups, aryl groups, substituted or unsubstituted amino groups, alkoxy groups, aryloxy groups, hydroxy groups, halogen atoms, more preferably hydrogen atoms. , An alkyl group having 1 to 20 carbon atoms, an amino group having 0 to 20 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, and a hydroxy group, more preferably a hydrogen atom and a carbon number. An alkyl group having 1 to 12 carbon atoms and an alkoxy group having 1 to 12 carbon atoms, particularly preferably a hydrogen atom.

More preferable as the general formula (103) is a compound represented by the following general formula (103-B).
General formula (103-B)

(Wherein R ³ and R ⁸ have the same meanings as those in formula (103-A), and preferred ranges are also the same. X ³ represents a hydrogen atom or a substituent.)

X ³ represents a hydrogen atom or a substituent. As the substituent, the above-described substituent T can be applied, and if possible, the substituent may be further substituted with another substituent. X ³ is preferably a hydrogen atom, an alkyl group, an aryl group, a cyano group, a nitro group, a carbonyl group, a sulfonyl group or an aromatic heterocyclic ring, more preferably a cyano group, a carbonyl group, a sulfonyl group or an aromatic heterocyclic ring. More preferably a cyano group or a carbonyl group, particularly preferably a cyano group or an alkoxycarbonyl group (—C (═O) OR (where R is an alkyl group having 1 to 20 carbon atoms, aryl having 6 to 12 carbon atoms). Group and a combination thereof).

As the general formula (103), a compound represented by the general formula (103-C) is more preferable.
General formula (103-C)

(Wherein R ³ and R ⁸ have the same meanings as those in formula (103-A), and the preferred range is also the same. R ²¹ represents an alkyl group having 1 to 20 carbon atoms.)

R ²¹ is preferably an alkyl group having 2 to 12 carbon atoms, more preferably an alkyl group having 4 to 12 carbon atoms, and still more preferably 6 carbon atoms when both R ³ and R ⁸ are hydrogen. To 12 alkyl groups, particularly preferably n-octyl group, tert-octyl group, 2-ethylhexyl group, n-decyl group, n-dodecyl group, most preferably 2-ethylhexyl. It is a group.

When R ³ and R ⁸ are preferably other than hydrogen as R ²¹ , the compound represented by the general formula (103-C) has a molecular weight of 300 or more and an alkyl group having 20 or less carbon atoms. preferable.

  The compound represented by the general formula (103) can be synthesized by the method described in Journal of American Chemical Society 63, 3452 (1941).

  Specific examples of the compound represented by the general formula (103) are given below, but the present invention is not limited to the following specific examples.

[Matting agent fine particles]
It is preferable to add fine particles as a matting agent to the transparent film of the present invention. The fine particles used in the present invention include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, silica Mention may be made of magnesium and calcium phosphates. Fine particles containing silicon are preferable from the viewpoint of low turbidity, and silicon dioxide is particularly preferable. The fine particles of silicon dioxide preferably have a primary average particle diameter of 20 nm or less and an apparent specific gravity of 70 g / liter or more. Those having an average primary particle size as small as 5 to 16 nm are more preferred because they can reduce the haze of the film. The apparent specific gravity is preferably 90 to 200 g / liter or more, and more preferably 100 to 200 g / liter or more. A larger apparent specific gravity is preferable because a high-concentration dispersion can be produced, and haze and aggregates are improved.

These fine particles usually form secondary particles having an average particle diameter of 0.1 to 3.0 μm, and these fine particles are present as aggregates of primary particles in the film, and 0.1 to 0.1 μm on the film surface. An unevenness of 3.0 μm is formed. The secondary average particle diameter is preferably from 0.1 μm to 1.5 μm. The primary and secondary particle sizes were determined by observing the particles in the film with a scanning electron microscope and determining the diameter of a circle circumscribing the particles as the particle size. In addition, 200 particles were observed at different locations, and the average value was taken as the average particle size.

  As fine particles of silicon dioxide, for example, commercially available products such as Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (above Nippon Aerosil Co., Ltd.) can be used. Zirconium oxide fine particles are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) and can be used.

  Among these, Aerosil 200V and Aerosil R972V are fine particles of silicon dioxide having a primary average particle diameter of 20 nm or less and an apparent specific gravity of 70 g / liter or more, and the coefficient of friction is maintained while keeping the turbidity of the optical film low. It is particularly preferable because it has a great effect of reducing the effect.

In order to obtain a transparent film having particles having a small secondary average particle size in the present invention, several methods are conceivable when preparing a dispersion of fine particles. For example, there is a method in which a fine particle dispersion obtained by stirring and mixing a solvent and fine particles is prepared in advance, and this fine particle dispersion is added to a small amount of polymer solution separately prepared, stirred and dissolved, and further mixed with the main dope solution. This method is a preferable preparation method in that the dispersibility of the silicon dioxide fine particles is good and the silicon dioxide fine particles are more difficult to reaggregate. In addition, after adding a small amount of cellulose ester to the solvent and dissolving with stirring, add the fine particles to this and disperse with a disperser to make this fine particle additive solution, and mix this fine particle additive solution with the dope solution using an inline mixer There is also a way to do it. The present invention is not limited to these methods, but the concentration of silicon dioxide when the silicon dioxide fine particles are mixed and dispersed with a solvent or the like is preferably 5 to 30% by mass, more preferably 10 to 25% by mass, and 15 to 20%. Mass% is most preferred. A higher dispersion concentration is preferable because the liquid turbidity with respect to the added amount is lowered, and haze and aggregates are improved. The addition amount of the matting agent in the final dope solution is preferably 0.01 to 1.0 g, more preferably 0.03 to 0.3 g, and most preferably 0.08 to 0.16 g per 1 m ² .

  The solvent used is preferably lower alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol and the like. Although it does not specifically limit as solvents other than a lower alcohol, It is preferable to use the solvent used at the time of film forming of a cellulose ester.

[Plasticizer, degradation inhibitor, release agent]
In addition to the above-mentioned compounds that optically reduce anisotropy and wavelength dispersion adjusting agents, the transparent film of the present invention has various additives (for example, plasticizers, ultraviolet inhibitors, etc.) according to the use in each preparation step. , Degradation inhibitors, release agents, infrared absorbers, etc.), which may be solid or oily. That is, the melting point and boiling point are not particularly limited. For example, mixing of ultraviolet absorbing material at 20 ° C. or lower and 20 ° C. or higher, and similarly, mixing of a plasticizer is described in, for example, Japanese Patent Application Laid-Open No. 2001-151901. Furthermore, infrared absorbing dyes are described, for example, in JP-A No. 2001-194522. Moreover, the addition time may be added at any time in the dope preparation step, but may be added by adding an additive to the final preparation step of the dope preparation step. Furthermore, the amount of each material added is not particularly limited as long as the function is manifested. Moreover, when a transparent film is formed from a multilayer, the kind and addition amount of the additive of each layer may differ. For example, although it describes in Unexamined-Japanese-Patent No. 2001-151902 etc., these are techniques conventionally known. For these details, materials described in detail on pages 16 to 22 in the Japan Institute of Invention Disclosure Technical Report (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention) are preferably used.

[Rate of compound addition]
In the transparent film of the present invention, the total amount of compounds having a molecular weight of 3000 or less is preferably 5 to 45% based on the polymer weight. More preferably, it is 10 to 40%, and even more preferably 15 to 30%. As described above, these compounds include compounds that reduce optical anisotropy, wavelength dispersion regulators, ultraviolet inhibitors, plasticizers, deterioration inhibitors, fine particles, release agents, infrared absorbers, etc. Is preferably 3000 or less, more preferably 2000 or less, and even more preferably 1000 or less. When the total amount of these compounds is 5% or less, the properties of the polymer alone are likely to be obtained, and there are problems such that the optical performance and physical strength are likely to fluctuate with changes in temperature and humidity. Moreover, when the total amount of these compounds is 45% or more, it exceeds the limit of compatibility of the compounds in the transparent film, and problems such as precipitation on the film surface and clouding of the film (crying out from the film) are likely to occur. .

[Organic solvent for polymer solution]
In the present invention, it is preferable to produce a transparent film by a solvent cast method, and the film is produced using a solution (dope) in which a polymer is dissolved in an organic solvent. The organic solvent preferably used as the main solvent of the present invention is preferably a solvent selected from esters, ketones, ethers having 3 to 12 carbon atoms, and halogenated hydrocarbons having 1 to 7 carbon atoms. Esters, ketones and ethers may have a cyclic structure. A compound having two or more functional groups of esters, ketones and ethers (that is, —O—, —CO— and —COO—) can also be used as a main solvent. It may have a functional group of In the case of the main solvent having two or more kinds of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group.

  As described above, for the transparent film of the present invention, a chlorinated halogenated hydrocarbon may be used as a main solvent, and as described in JIII Journal of Technical Disclosure 2001-1745 (pages 12 to 16), non-chlorine. A system solvent may be used as the main solvent, and is not particularly limited for the transparent film of the present invention.

  In addition, the solvent about the dope solution and film of this invention is disclosed by the following patents including the melt | dissolution method, and is a preferable aspect. They are, for example, JP 2000-95876, JP 12-95877, JP 10-324774, JP 8-152514, JP 10-330538, JP 9-95538, JP 9-95557, JP 10-10. -235664, JP-A-12-63534, JP-A-11-21379, JP-A-10-182853, JP-A-10-278056, JP-A-10-279702, JP-A-10-323853, JP-A-10-237186, JP-A-11-60807. JP-A-11-152342, JP-A-11-292988, JP-A-11-60752, JP-A-11-60752, and the like. According to these patents, not only the preferred solvent for the polymer of the present invention, but also the physical properties of the solution and coexisting coexisting substances are described, and this is also a preferred embodiment in the present invention.

[Transparent film manufacturing process]
[Dissolution process]
In the preparation of the polymer solution (dope) of the present invention, the dissolution method is not particularly limited, and may be performed at room temperature or further by a cooling dissolution method or a high temperature dissolution method, or a combination thereof. Regarding the preparation of the polymer solution in the present invention, as well as the solution concentration and filtration steps involved in the dissolution step, the Technical Report of the Invention Association (Technical Number 2001-1745, published on March 15, 2001, Invention Association) Production processes described in detail on pages 22 to 25 are preferably used.

(Transparency of dope solution)
The dope transparency of the polymer solution of the present invention is preferably 85% or more. More preferably, it is 88% or more, and more preferably 90% or more. In the present invention, it was confirmed that various additives were sufficiently dissolved in the dope solution. As a specific method for calculating the dope transparency, the dope solution was poured into a 1 cm square glass cell, and the absorbance at 550 nm was measured with a spectrophotometer (UV-3150, Shimadzu Corporation). Only the solvent was measured in advance as a blank, and the transparency of the dope solution was calculated from the ratio to the absorbance of the blank.

[Casting, drying, winding process]
Next, a method for producing a film using the polymer solution of the present invention will be described. For the method and equipment for producing the transparent film of the present invention, a solution casting film forming method and a solution casting film forming apparatus conventionally used for producing a cellulose triacetate film are used. The dope (polymer solution) prepared from the dissolving machine (kettle) is temporarily stored in a storage kettle, and the foam contained in the dope is defoamed for final preparation. The dope is sent from the dope discharge port to the pressure die through a pressure metering gear pump capable of delivering a constant amount of liquid with high accuracy, for example, by the number of rotations, and the dope is run endlessly from the die (slit) of the pressure die. The dry-dried dope film (also referred to as web) is peeled off from the metal support at a peeling point that is uniformly cast on the metal support and substantially rounds the metal support. Both ends of the obtained web are sandwiched between clips, and are transported by a tenter while holding the width (it can also be stretched in the film width direction by this tenter) and dried, and then the obtained film is machined by a roll group of a drying device. After being conveyed, the drying is finished, and it is wound up to a predetermined length in a roll by a winder. The combination of the tenter and the roll group dryer varies depending on the purpose. In the solution casting film forming method used for the functional protective film or the silver halide photographic light-sensitive material which is an optical member for electronic display, which is the main use of the cellulose acylate film of the present invention, a solution casting film forming apparatus In addition, a coating apparatus is often added for surface processing on films such as an undercoat layer, an antistatic layer, an antihalation layer, and a protective layer. These are described in detail on pages 25-30 in the Japan Society for Invention and Innovation Technical Report (Public Technical Number 2001-1745, issued on March 15, 2001, Japan Society for Invention). Including), metal support, drying, peeling and the like, and can be preferably used in the present invention.

[Film characteristics]
(Change in optical performance of film after high humidity treatment)
Regarding the change of the optical performance due to the environmental change of the transparent film of the present invention, it is preferable that the change amount of Re and Rth of the film treated at 60 ° C. and 90% RH for 240 hours is 15 nm or less. More preferably, it is 12 nm or less, and more preferably 10 nm or less.

(Humidity dependence of film Re and Rth)
It is preferable that both the in-plane retardation Re and the thickness direction retardation Rth of the transparent film of the present invention have small changes due to humidity. Specifically, the difference ΔRth (= Rth10% RH−Rth80% RH) between the Rth value at 25 ° C. and 10% RH and the Rth value at 25 ° C. and 80% RH is preferably 0 to 50 nm. More preferably, it is 0-40 nm, More preferably, it is 0-35 nm.

(Change in optical performance of film after high temperature treatment)
Further, it is desirable that the amount of change in Re and Rth of the film treated at 80 ° C. for 240 hours is 15 nm or less. More preferably, it is 12 nm or less, and more preferably 10 nm or less.

(Compound volatilization after film heat treatment)
The Rth-reducing compound and the ΔRth-reducing compound that can be preferably used in the transparent film of the present invention have a volatilization amount of the compound from a film treated at 80 ° C. for 240 hours of 30% or less. It is not good. More preferably, it is 25% or less, and more preferably 20% or less.
The amount of volatilization from the film was determined by dissolving the film treated at 80 ° C. for 240 hours and the untreated film in a solvent, detecting the compound by liquid high performance chromatography, and determining the peak area of the compound in the film The amount was calculated by the following formula.
Volatilization amount (%) = {(Amount of remaining compound in untreated product) − (Amount of remaining compound in treated product)} / (Amount of remaining compound in untreated product) × 100

(Glass glass transition temperature Tg)
The glass transition temperature Tg of the transparent film of the present invention is 80 to 165 ° C. From the viewpoint of heat resistance, Tg is more preferably 100 to 160 ° C, and particularly preferably 110 to 150 ° C. The glass transition temperature Tg is measured with a differential scanning calorimeter (DSC2910, T.A. Instruments) for 10 mg of the transparent film sample of the present invention from room temperature to 200 ° C. at a heating / cooling rate of 5 ° C./min. The glass transition temperature Tg was calculated.

(Haze of film)
The haze of the transparent film of the present invention is preferably 0.01 to 2.0%. More preferably, it is 0.05 to 1.5%, and more preferably 0.1 to 1.0%. As an optical film, the transparency of the film is important. The haze was measured by measuring a transparent film sample 40 mm × 80 mm of the present invention at 25 ° C. and 60% RH with a haze meter (HGM-2DP, Suga Test Instruments) according to JIS K-6714.

(Equilibrium moisture content of film)
The equilibrium moisture content of the transparent film of the present invention is such that when used as a protective film for a polarizing plate, the adhesiveness with a water-soluble polymer such as polyvinyl alcohol is not impaired. It is preferable that the equilibrium water content in is 0 to 4%. It is more preferably 0.1 to 3.5%, and particularly preferably 1 to 3%. When the equilibrium moisture content is 4% or more, the dependency of retardation due to humidity change becomes too large when used as a support for an optical compensation film.
The water content was measured by measuring the transparent film sample 7 mm × 35 mm of the present invention by the Karl Fischer method using a moisture measuring device and a sample drying apparatus (CA-03, VA-05, both Mitsubishi Chemical Corporation). It was calculated by dividing the amount of water (g) by the sample weight (g).

(Water permeability of film)
The moisture permeability of the transparent film used for the optical compensation sheet of the present invention is JIS standard JIS Z02.
Based on 08, it is preferably measured at a temperature of 60 ° C. and a humidity of 95% RH, and is 400 to 2000 g / m ² · 24 h in terms of a film thickness of 80 μm. More preferably 500~1800g / m ² · 24h, and particularly preferably 600~1600g / m ² · 24h. If it exceeds 2000 g / m ² · 24 h, the tendency of the absolute value of the humidity dependence of the Re value and Rth value of the film to exceed 0.5 nm /% RH becomes strong. Also, when an optically anisotropic film is formed by laminating an optically anisotropic layer on the transparent film of the present invention, the absolute value of the humidity dependence of the Re value and Rth value tends to exceed 0.5 nm /% RH. This is not preferable. When this optical compensation sheet or polarizing plate is incorporated in a liquid crystal display device, it causes a change in color and a decrease in viewing angle. In addition, when the moisture permeability of the transparent film is less than 400 g / m ² · 24 h, when the polarizing plate is produced by being attached to both surfaces of the polarizing film, the transparent film prevents the adhesive from being dried, resulting in poor adhesion.
If the film thickness of the transparent film is thick, the moisture permeability becomes small, and if the film thickness is thin, the moisture permeability becomes large. Therefore, it is necessary to convert the sample of any film thickness to a standard of 80 μm. The conversion of the film thickness was obtained as (water permeability in terms of 80 μm = measured moisture permeability × measured film thickness μm / 80 μm).
The measurement method of moisture permeability is “Polymer Physical Properties II” (Polymer Experiment Course 4, Kyoritsu Shuppan), pages 285-294: Measurement of vapor permeation amount (mass method, thermometer method, vapor pressure method, adsorption amount method) The transparent film sample 70 mmφ of the present invention was conditioned at 25 ° C., 90% RH, 60 ° C., and 95% RH for 24 hours, respectively, and a moisture permeability test apparatus (KK-709007, Toyo Seiki Co., Ltd.) calculated the amount of water per unit area (g / m ² ) according to JIS Z-0208, and determined moisture permeability = weight after humidity adjustment−weight before humidity adjustment.

(Dimensional change of film)
The dimensional stability of the transparent film of the present invention is such that the dimensional change rate when left standing for 24 hours under conditions of 60 ° C. and 90% RH (high humidity) and 24 hours under conditions of 90 ° C. and 5% RH. It is desirable that the dimensional change rate after standing (high temperature) is 0.5% or less. More preferably, it is 0.3% or less, and even more preferably, it is 0.15% or less.
As a specific measurement method, two transparent film samples 30 mm × 120 mm were prepared, humidity-controlled at 25 ° C. and 60% RH for 24 hours, and an automatic pin gauge (Shinto Kagaku Co., Ltd.) with 6 mmφ at both ends. Holes were drilled at intervals of 100 mm to obtain the original punch spacing (L0). Punch interval size (L1) after one sample was treated at 60 ° C. and 90% RH for 24 hours, punch after one sample was treated at 90 ° C. and 5% RH for 24 hours The spacing dimension (L2) was measured. Measurement was made to a minimum scale of 1/1000 mm at all intervals. Dimensional change rate of 60 ° C. and 90% RH (high humidity) = {| L0−L1 | / L0} × 100, Dimensional change rate of 90 ° C. and 5% RH (high temperature) = {| L0−L2 | / The dimensional change rate was determined as L0} × 100.

(Elastic modulus of film)
Elastic modulus of the transparent film of the present invention is preferably ^{200~500kgf / mm 2 (1960~4900N / mm} 2), more preferably ^{240~470kgf / mm 2 (2350~4610N / mm} 2), more preferably from ^{270~440kgf / mm 2 (2650~4315N / mm} 2). As a specific measurement method, Toyo Baldwin Universal Tensile Tester STM T50BP was used to measure the stress at 0.5% elongation in a 23 ° C, 70% atmosphere at a pulling rate of 10% / min to obtain the elastic modulus. It was.

(Chromatic dispersion of Re and Rth)
The transparent film of the present invention preferably has | Re ₍₄₀₀₎ −Re ₍₇₀₀₎ | ≦ 10 and | Rth ₍₄₀₀₎ −Rth ₍₇₀₀₎ | ≦ 35. More preferably, | Re ₍₄₀₀₎ −Re ₍₇₀₀₎ | ≦ 5 and | Rth ₍₄₀₀₎ −Rth ₍₇₀₀₎ | ≦ 25, and | Re ₍₄₀₀₎ −Re ₍₇₀₀₎ | ≦ 3 And | Rth ₍₄₀₀₎ −Rth ₍₇₀₀₎ | ≦ 15 is particularly desirable.
As a specific measurement method, the sample was conditioned at 25 ° C. and 60% RH for 2 hours, and light with a wavelength of 780 nm to 380 nm was incident in the normal direction of the film on an ellipsometer M-150 (manufactured by JASCO Corporation). Thus, Re at each wavelength was determined, and the wavelength dispersion of Re was measured. Further, the wavelength dispersion of Rth was measured by introducing light having a wavelength of 780 to 380 nm from the direction inclined by + 40 ° with respect to the normal direction of the film with the slow axis in the plane as the tilt axis. The value and the retardation value measured by making light with a wavelength of 780 to 380 nm incident from a direction inclined by −40 ° with respect to the film normal direction with the in-plane slow axis as the tilt axis were measured in a total of three directions. Based on the retardation value, it was calculated by inputting the assumed average refractive index of 1.48 and the film thickness.

(Film surface properties)
The surface of the transparent film of the present invention preferably has an arithmetic average roughness (Ra) of surface irregularities of the film based on JISB0601-1994 of 0.1 μm or less and a maximum height (Ry) of 0.5 μm or less. Preferably, the arithmetic average roughness (Ra) is 0.05 μm or less, and the maximum height (Ry) is 0.2 μm or less. The concave and convex shapes on the film surface can be evaluated by an atomic force microscope (AFM).

(Retention of film)
In the transparent film of the present invention, retention of various compounds added to the film is required. Specifically, the mass change of the film when the transparent film of the present invention is allowed to stand for 48 hours under the condition of 80 ° C./90% RH is preferably 0 to 5%. More preferably, it is 0 to 3%, and still more preferably 0 to 2%.
<Reservation evaluation method>
The sample was cut to a size of 10 cm × 10 cm, and the mass after being allowed to stand for 24 hours in an atmosphere of 23 ° C. and 55% RH was measured, and left for 48 hours under the conditions of 80 ± 5 ° C. and 90 ± 10% RH. . The surface of the sample after the treatment was lightly wiped, the mass after standing for 1 day at 23 ° C. and 55% RH was measured, and the retention was calculated by the following method.
Retention property (mass%) = {(mass before standing−mass after standing) / mass before standing} × 100

(Tear strength of film)
The tear strength (Elmendorf tear method) based on the tear test method of JIS K7128-2: 1998 is preferably 2 g or more in the range where the film thickness of the transparent film of the present invention is 20 to 80 μm. More preferably, it is 5-25g, Furthermore, it is 6-25g. Moreover, 8 g or more is preferable at 60 micrometer conversion, More preferably, it is 8-15g. Specifically, it can be measured using a light load tear strength tester after conditioning a sample piece of 50 mm × 64 mm under the conditions of 25 ° C. and 65% RH for 2 hours.

(Residual solvent amount of film)
It is preferable to dry on the conditions which the amount of residual solvents with respect to the transparent film of this invention becomes the range of 0.01-1.5 mass%. More preferably, it is 0.01-0.5 mass%. The durability of the film is improved by reducing the amount of residual solvent.

(surface treatment)
The transparent film can achieve improved adhesion between the transparent film and each functional layer (for example, the undercoat layer and the back layer) by performing a surface treatment as the case may be. For example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used. The glow discharge treatment here may be low-temperature plasma that occurs in a low-pressure gas of 10 ^{−3 to} 20 Torr, and plasma treatment under atmospheric pressure is also preferable. A plasma-excitable gas is a gas that is plasma-excited under the above conditions, and includes chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof. It is done. Details of these are described in detail in pages 30 to 32 in the Japan Institute of Invention Disclosure Technical Bulletin (Public Technical No. 2001-1745, published on March 15, 2001, Japan Institute of Invention), and are preferably used in the present invention. be able to.

(Contact angle of film surface by alkali saponification treatment)
Alkali saponification is one effective means of surface treatment when the transparent film of the present invention is used as a transparent protective film for polarizing plates. In this case, the contact angle on the film surface after the alkali saponification treatment is preferably 55 ° or less. More preferably, it is 50 ° or less, and more preferably 45 ° or less. The contact angle evaluation method can be used as an evaluation of hydrophilicity / hydrophobicity by an ordinary method in which water drops are dropped on the surface of the film after the alkali saponification treatment and the angle formed by the film surface and the water drops is determined.

(Light resistance)
As an index of the transparent light durability of the present invention, it is preferable that the color difference ΔE ^* ab of the film irradiated with super xenon light for 240 hours is 20 or less. More preferably, it is 18 or less, and more preferably 15 or less. The color difference was measured using UV3100 (manufactured by Shimadzu Corporation). The measurement was carried out by adjusting the film to 25 ° C. and 60% RH for 2 hours or more, and then measuring the color of the film before irradiation with xenon light to determine initial values (L0 ^* , a0 ^* , b0 ^* ). Thereafter, the film alone was irradiated with xenon light for 240 hours under conditions of 150 W / m ² , 60 ° C. and 50% RH with a Super Xenon Weather Meter SX-75 (manufactured by Suga Test Instruments Co., Ltd.). After the elapse of a predetermined time, the film was taken out from the thermostat, adjusted to 25 ° C. and 60% RH for 2 hours, and then subjected to color measurement again to obtain values after irradiation (L1 ^* , a1 ^* , b1 ^* ). . From these, the color difference ΔE ^* ab = ((L0 ^* −L1 ^* ) ² + (a0 ^* −a1 ^* ) ² + (b0 ^* −b1 ^* ) ² ) ^0.5 was obtained.

(Transparent film with positive intrinsic birefringence)
The transparent film of the present invention has a large in-plane retardation Re when stretched in the direction having a slow axis in the film plane, and a small in-plane retardation Re when stretched in a direction perpendicular to the direction having the slow axis. Become. This indicates that the intrinsic birefringence is positive, and it is effective to stretch in the direction perpendicular to the slow axis in order to cancel the Re developed in the film. As this method, for example, when the film has a slow axis in the machine conveyance direction (MD direction), it is conceivable to reduce Re using tenter stretching in a direction perpendicular to MD (TD direction). . As an opposite example, when the slow axis is in the TD direction, it is conceivable that Re is reduced by increasing the tension of the machine transport roll in the MD direction and stretching.

(Transparent film with negative intrinsic birefringence)
When the transparent film of the present invention is stretched in a direction having a slow axis, the in-plane retardation Re may be reduced, and when it is stretched in a direction perpendicular to the direction having a slow axis, the in-plane retardation Re may be increased. This indicates that the intrinsic birefringence is negative, and it is effective to stretch in the same direction as the slow axis in order to cancel out the Re developed in the film. As this method, for example, when the film has a slow axis in the machine conveyance direction (MD direction), Re can be reduced by increasing the tension of the machine conveyance roll in the MD direction and stretching. As an opposite example, in the case where the TD direction has a slow axis, it is conceivable to reduce Re by using tenter stretching in a direction perpendicular to MD (TD direction).

[Usage]
It is used for the transparent film, optical application, photographic photosensitive material and the like of the present invention. Is preferably a liquid crystal display device for optical use, and the liquid crystal display device has a liquid crystal cell in which a liquid crystal is supported between two electrode substrates, two polarizing elements disposed on both sides thereof, and It is further preferable that at least one optical compensation sheet is disposed between the liquid crystal cell and the polarizing element. As these liquid crystal display devices, TN, IPS, FLC, AFLC, OCB, STN, ECB, VA and HAN are preferable.

[Functional layer]
When the transparent film of the present invention is used for the optical application as described above, various functional layers are provided. They are, for example, an antistatic layer, a cured resin layer (transparent hard coat layer), an antireflection layer, an easy adhesion layer, an antiglare layer, an optical compensation layer, an alignment layer, a liquid crystal layer, and the like. These functional layers and materials for which the transparent film of the present invention can be used include surfactants, slip agents, matting agents, antistatic layers, hard coat layers, and the like. No. 2001-1745, issued March 15, 2001, Invention Association), and are described in detail on pages 32 to 45, and can be preferably used in the present invention.

[Application (Polarizing plate)]
The use of the transparent film of the present invention will be described.
The optical film of the present invention is particularly useful for a polarizing plate protective film. When using as a polarizing plate protective film, the manufacturing method of a polarizing plate is not specifically limited, It can manufacture by a general method. There is a method in which the obtained transparent film is treated with an alkali and bonded to both surfaces of a polarizer prepared by immersing and stretching a polyvinyl alcohol film in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution. Instead of alkali treatment, easy adhesion processing as described in JP-A-6-94915 and JP-A-6-118232 may be performed.
Examples of the adhesive used for bonding the protective film treated surface and the polarizer include polyvinyl alcohol adhesives such as polyvinyl alcohol and polyvinyl butyral, vinyl latexes such as butyl acrylate, and the like.
The polarizing plate is composed of a polarizer and a protective film that protects both surfaces of the polarizer, and is further constructed by laminating a protective film on one surface of the polarizing plate and a separate film on the opposite surface. The protective film and the separate film are used for the purpose of protecting the polarizing plate at the time of shipping the polarizing plate and at the time of product inspection. In this case, the protect film is bonded for the purpose of protecting the surface of the polarizing plate, and is used on the side opposite to the surface where the polarizing plate is bonded to the liquid crystal plate. Moreover, a separate film is used in order to cover the adhesive layer bonded to a liquid crystal plate, and is used for the surface side which bonds a polarizing plate to a liquid crystal plate.
In a liquid crystal display device, a substrate containing liquid crystal is usually disposed between two polarizing plates. However, a polarizing plate protective film to which the optical film of the present invention is applied can provide excellent display properties regardless of the location. . In particular, the polarizing plate protective film on the outermost surface of the display side of the liquid crystal display device is provided with a transparent hard coat layer, an antiglare layer, an antireflection layer, and the like.

[Application (Optical compensation film)]
The transparent film of the present invention can be used in various applications, and is particularly effective when used with an optical compensation film of a liquid crystal display device. The optical compensation film is generally used for a liquid crystal display device, refers to an optical material that compensates for a phase difference, and is synonymous with a phase difference plate, an optical compensation sheet, and the like. The optical compensation film has birefringence and is used for the purpose of removing the color of the display screen of the liquid crystal display device or improving the viewing angle characteristics. The transparent film of the present invention has a small Re and Rth, does not cause excessive anisotropy, and when an optically anisotropic layer having birefringence is used in combination, only the optical performance of the optically anisotropic layer can be exhibited.

Therefore, when the transparent film of the present invention is used as an optical compensation film for a liquid crystal display device, Re and Rth of the optically anisotropic layer used in combination are preferably Re = 0 to 200 nm and | Rth | = 0 to 400 nm. Any optically anisotropic layer may be used as long as it is within the range. The optical performance and driving method of the liquid crystal cell of the liquid crystal display device in which the transparent film of the present invention is used are not limited, and any optical anisotropic layer required as an optical compensation film can be used in combination. The optically anisotropic layer used in combination may be formed from a composition containing a liquid crystalline compound or may be formed from a polymer film having birefringence.
The liquid crystal compound is preferably a discotic liquid crystal compound or a rod-like liquid crystal compound.

(Discotic liquid crystalline compounds)
Examples of discotic liquid crystalline compounds that can be used in the present invention include various documents (C. Destrade et al., Mol. Crysr. Liq. Cryst., Vol. 71, page 111 (1981); edited by the Chemical Society of Japan). , Quarterly Chemistry Review, No. 22, Liquid Crystal Chemistry, Chapter 5, Chapter 10 Section 2 (1994); B. Kohne et al., Angew. Chem. Soc. Chem. Comm., Page 1794 (1985). J. Zhang et al., J. Am.Chem.Soc., Vol.116, page 2655 (1994)).

  In the optically anisotropic layer, the discotic liquid crystalline molecules are preferably fixed in an aligned state, and most preferably fixed by a polymerization reaction. The polymerization of discotic liquid crystalline molecules is described in JP-A-8-27284. In order to fix the discotic liquid crystalline molecules by polymerization, it is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystalline molecules. However, when the polymerizable group is directly connected to the disc-shaped core, it becomes difficult to maintain the orientation state in the polymerization reaction. Therefore, a linking group is introduced between the discotic core and the polymerizable group. JP-A-2001-4387 discloses a discotic liquid crystalline molecule having a polymerizable group.

(Bar-shaped liquid crystalline compound)
Examples of rod-like liquid crystalline compounds that can be used in the present invention include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, and cyano-substituted compounds. Phenyl pyrimidines, alkoxy substituted phenyl pyrimidines, phenyl dioxanes, tolanes and alkenyl cyclohexyl benzonitriles are included. Not only the above low-molecular liquid crystalline compounds but also high-molecular liquid crystalline compounds can be used.

  In the optically anisotropic layer, the rod-like liquid crystalline molecules are preferably fixed in an aligned state, and most preferably fixed by a polymerization reaction. Examples of polymerizable rod-like liquid crystalline compounds that can be used in the present invention include Makromol. Chem. 190, 2255 (1989), Advanced Materials 5, 107 (1993), US Pat. Nos. 4,683,327, 5,622,648 and 5,770,107, World Patents (WO) 95/22586, 95/24455. No. 97/00600, No. 98/23580, No. 98/52905, JP-A-1-272551, JP-A-6-16616, JP-A-7-110469, JP-A-11-80081, and JP-A-2001-2001. And the compounds described in US Pat.

(Optically anisotropic layer made of polymer film)
As described above, the optically anisotropic layer may be formed from a polymer film. The polymer film is formed from a polymer that can exhibit optical anisotropy. Examples of such polymers include polyolefins (eg, polyethylene, polypropylene, norbornene polymers), polycarbonates, polyarylate, polysulfone, polyvinyl alcohol, polymethacrylic acid esters, polyacrylic acid esters and cellulose esters (eg, cellulose triacetate, Cellulose diacetate). Further, a copolymer or a polymer mixture of these polymers may be used.

  The optical anisotropy of the polymer film is preferably obtained by stretching. The stretching is preferably uniaxial stretching or biaxial stretching. Specifically, longitudinal uniaxial stretching using a difference in peripheral speed between two or more rolls, tenter stretching for grasping both sides of the polymer film and stretching in the width direction, or biaxial stretching in combination of these is preferable. In addition, using two or more polymer films, the optical properties of the entire two or more films may satisfy the above conditions. The polymer film is preferably produced by a solvent cast method in order to reduce unevenness in birefringence. The thickness of the polymer film is preferably 20 to 500 μm, and most preferably 40 to 100 μm.

Further, as the polymer film forming the optically anisotropic layer, at least one polymer material selected from the group consisting of polyamide, polyimide, polyester, polyetherketone, polyamideimide polyesterimide, and polyaryletherketone is used. A method in which a solution in which is dissolved in a solvent is applied to a substrate and the solvent is dried to form a film can be preferably used. At this time, a method of stretching the polymer film and the base material to develop optical anisotropy and using it as an optical anisotropic layer can be preferably used, and the transparent film of the present invention is preferably used as the base material. Can do. Alternatively, the polymer film may be prepared on another substrate, and the polymer film may be peeled off from the substrate and then bonded to the transparent film of the present invention, and used as an optically anisotropic layer. preferable. In this method, the thickness of the polymer film can be reduced, and is preferably 50 μm or less, and more preferably 1 to 20 μm.

(General liquid crystal display device configuration)
When a transparent film is used as the optical compensation film, the transmission axis of the polarizing element and the slow axis of the optical compensation film may be arranged at any angle. The liquid crystal display device includes a liquid crystal cell having a liquid crystal supported between two electrode substrates, two polarizing elements disposed on both sides thereof, and at least one sheet between the liquid crystal cell and the polarizing element. The optical compensation film is arranged.
The liquid crystal layer of the liquid crystal cell is usually formed by sealing liquid crystal in a space formed by sandwiching a spacer between two substrates. The transparent electrode layer is formed on the substrate as a transparent film containing a conductive substance. The liquid crystal cell may further be provided with a gas barrier layer, a hard coat layer, or an undercoat layer (undercoat layer) (used for adhesion of the transparent electrode layer). These layers are usually provided on the substrate. The substrate of the liquid crystal cell generally has a thickness of 50 μm to 2 mm.

(Types of liquid crystal display devices)
The transparent film of the present invention can be used for liquid crystal cells in various display modes. TN (Twisted Nematic), IPS (In-Plane Switching), FLC (Ferroelectric Liquid Crystal), AFLC (Anti-Ferroly Liquid Liquid Crystal), OCB (Optically Liquid BTS). Various display modes such as ECB (Electrically Controlled Birefringence) and HAN (Hybrid Aligned Nematic) have been proposed. In addition, a display mode in which the above display mode is oriented and divided has been proposed. The transparent film of the present invention is effective in any display mode liquid crystal display device. Further, it is effective in any of a transmissive type, a reflective type, and a transflective liquid crystal display device.

(TN type liquid crystal display device)
You may use the transparent film of this invention as a support body or polarizing plate protective film of the optical compensation sheet | seat of a TN type liquid crystal display device which has a TN mode liquid crystal cell. TN mode liquid crystal cells and TN type liquid crystal display devices have been well known for a long time. The optical compensation sheet used in the TN type liquid crystal display device is described in JP-A-3-9325, JP-A-6-148429, JP-A-8-50206, and JP-A-9-26572. Moreover, it is described in Mori et al. (Jpn. J. Appl. Phys. Vol. 36 (1997) p. 143 and Jpn. J. Appl. Phys. Vol. 36 (1997) p. 1068). is there.

(STN type liquid crystal display device)
You may use the transparent film of this invention as a support body or polarizing plate protective film of the optical compensation sheet | seat of the STN type liquid crystal display device which has a liquid crystal cell of STN mode. In general, in a STN type liquid crystal display device, rod-like liquid crystalline molecules in a liquid crystal cell are twisted in the range of 90 to 360 degrees, and the refractive index anisotropy (Δn) and cell gap (d) of the rod-like liquid crystalline molecules. Product (Δnd) is in the range of 300 to 1500 nm. The optical compensation sheet used in the STN type liquid crystal display device is described in JP-A-2000-105316.

(VA type liquid crystal display device)
The transparent film of the present invention may be used as a support for an optical compensation sheet or a polarizing plate protective film for a VA liquid crystal display device having a VA mode liquid crystal cell. It is preferable that the Re retardation value of the optical compensation sheet used in the VA liquid crystal display device is 0 to 150 nm and the Rth retardation value is 70 to 400 nm. The Re retardation value is more preferably 20 to 70 nm. When two optically anisotropic polymer films are used in the VA liquid crystal display device, the Rth retardation value of the film is preferably 70 to 250 nm. When a single optically anisotropic polymer film is used for the VA liquid crystal display device, the Rth retardation value of the film is preferably 150 to 400 nm. The VA-type liquid crystal display device may be an alignment-divided system as described in, for example, JP-A-10-123576.

(IPS liquid crystal display device and ECB liquid crystal display device)
The transparent film of the present invention is particularly advantageously used as a support for an optical compensation sheet of an IPS liquid crystal display device and an ECB liquid crystal display device having IPS mode and ECB mode liquid crystal cells, or as a protective film for a polarizing plate. In these modes, the liquid crystal material is aligned substantially in parallel during black display, and black is displayed by aligning liquid crystal molecules in parallel with the substrate surface in the absence of applied voltage. In these embodiments, the polarizing plate using the transparent film of the present invention contributes to the improvement of the color tone, the expansion of the viewing angle, and the improvement of the contrast. In this embodiment, among the protective films for the polarizing plates above and below the liquid crystal cell, the polarizing film using the transparent film of the present invention for the protective film (cell-side protective film) disposed between the liquid crystal cell and the polarizing plate. It is preferable to use the plate on at least one side. More preferably, an optically anisotropic layer is disposed between the protective film of the polarizing plate and the liquid crystal cell, and the retardation value of the disposed optically anisotropic layer is twice the value of Δn · d of the liquid crystal layer. It is preferable to set as follows.

(OCB type liquid crystal display device and HAN type liquid crystal display device)
The transparent film of the present invention may be used as a support for an optical compensation sheet or a polarizing plate protective film for an OCB type liquid crystal display device having an OCB mode liquid crystal cell or a HAN type liquid crystal display device having a HAN mode liquid crystal cell. In the optical compensation sheet used for the OCB type liquid crystal display device or the HAN type liquid crystal display device, it is preferable that the direction in which the absolute value of retardation is minimum does not exist in the plane of the optical compensation sheet or in the normal direction. The optical properties of the optical compensation sheet used in the OCB type liquid crystal display device or the HAN type liquid crystal display device are also the optical properties of the optical anisotropic layer, the optical properties of the support, and the optical anisotropic layer and the support. Is determined by the arrangement of An optical compensation sheet used for an OCB type liquid crystal display device or a HAN type liquid crystal display device is described in JP-A-9-197397. Further, it is described in a paper by Mori et al. (Jpn. J. Appl. Phys. Vol. 38 (1999) p. 2837).

(Reflective liquid crystal display)
The transparent film of the present invention may be used as an optical compensation sheet or a polarizing plate protective film of a TN type, STN type, HAN type, GH (Guest-Host) type reflective liquid crystal display device. These display modes have been well known since ancient times. The TN type reflection type liquid crystal display device is described in JP-A-10-123478, WO98848320, and Japanese Patent No. 3022477. The optical compensation sheet used in the reflective liquid crystal display device is described in WO00-65384.

(Other liquid crystal display devices)
The transparent film of the present invention may also be used as a support for an optical compensation sheet or a polarizing plate protective film of an ASM type liquid crystal display device having a liquid crystal cell in an ASM (axially aligned microcell) mode. The mode liquid crystal cell is characterized in that the cell thickness is maintained by a position-adjustable resin spacer. Other properties are the same as those of the TN mode liquid crystal cell. The ASM mode liquid crystal cell and the ASM type liquid crystal display device are described in a paper by Kume et al. (Kume et al., SID 98 Digest 1089 (1998)).

(Hard coat film, antiglare film, antireflection film)
The transparent film of the present invention can be preferably applied to a hard coat film, an antiglare film and an antireflection film. For the purpose of improving the visibility of flat panel displays such as LCD, PDP, CRT, EL, etc., any or all of a hard coat layer, an antiglare layer and an antireflection layer are provided on one or both sides of the transparent film of the present invention. be able to. Preferred embodiments of such an antiglare film and antireflection film are described in detail in pages 54 to 57 of the Japan Institute of Invention and Technology (Publication No. 2001-1745, published on March 15, 2001, Japan Society of Invention). The transparent film of the present invention can be preferably used.

(Transparent substrate)
The transparent film of the present invention has an optical anisotropy close to zero and has excellent transparency. Therefore, the transparent film is used as an alternative to a liquid crystal cell glass substrate of a liquid crystal display device, that is, as a transparent substrate for enclosing a driving liquid crystal. be able to.
Since the transparent substrate enclosing the liquid crystal needs to have excellent gas barrier properties, a gas barrier layer may be provided on the surface of the transparent film of the present invention as necessary. The form and material of the gas barrier layer are not particularly limited. However, SiO ₂ or the like is vapor-deposited on at least one side of the transparent film of the present invention, or a polymer having a relatively high gas barrier property such as a vinylidene chloride polymer or a vinyl alcohol polymer. The method of providing the coating layer of this can be considered, and these can be used suitably.
In order to use as a transparent substrate for enclosing liquid crystal, a transparent electrode for driving the liquid crystal by applying a voltage may be provided. Although it does not specifically limit as a transparent electrode, A transparent electrode can be provided by laminating | stacking a metal film, a metal oxide film, etc. on the at least single side | surface of the transparent film of this invention. Among these, a metal oxide film is preferable from the viewpoint of transparency, conductivity, and mechanical properties, and an indium oxide thin film mainly containing 2 to 15% of zinc oxide can be preferably used. Details of these techniques are disclosed in, for example, Japanese Patent Application Laid-Open Nos. 2001-125079 and 2000-227603.

  The present invention will be described more specifically with reference to the following examples. The materials, reagents, ratios, operations, and the like shown in the following examples can be appropriately changed without departing from the technical idea of the present invention, and the scope of the present invention is not limited to the specific examples shown below.

[Preparation of cellulose acylate film]
Example 1-1
(Preparation of cellulose acylate film 101)
The following composition was put into a mixing tank, stirred while heating to dissolve each component, and a cellulose acylate solution A was prepared.

<Composition of cellulose acylate solution A>
Cellulose acetate with a substitution degree of 2.86 100 parts by weight Methylene chloride (first solvent) 517.6 parts by weight Methanol (second solvent) 77.3 parts by weight Silica particles with an average particle diameter of 16 nm 0.13 parts by weight (AEROSIL R972, Nippon Aerosil Co., Ltd.)
Compound (A-7) for reducing optical anisotropy 12.0 parts by mass

The cellulose acylate solution A was cast using a band casting machine, and the film was peeled off from the band with a residual solvent amount of about 60% and conveyed by a tenter.
The average temperature of the drying zone is 135 ° C, and an online birefringence meter is installed in the production line to measure the retardation profile in the width direction of the film. Based on the retardation value obtained from the online birefringence meter The tenter magnification and the drying zone conditions were automatically adjusted so as to reduce the retardation variation of the film.
The finished cellulose acylate film 101 had a residual solvent amount of 0.15%, a roll width of 1000 mm, and a film thickness of 80 μm. Table 1 shows Re and Rth of the obtained film, variation in the width direction thereof, and variation in the axis.

Example 1-2
(Preparation of cellulose acylate film 102)
A cellulose acylate film 102 was produced in the same manner except that the cellulose acylate solution was changed to the following composition in Example 1-1. In this example, the compound (A-19) and the wavelength dispersion adjusting agent (UV-102) that reduce the optical anisotropy so as to reduce the retardation variation of the film based on the values obtained by the on-line birefringence meter. The addition amount was adjusted. Further, cellulose acetate having a substitution degree of 2.95 was prepared in another tank, and the average substitution degree of the cotton to be formed was simultaneously adjusted by adding it to the original cotton.
Table 1 shows Re and Rth of the obtained film, variation in the width direction thereof, and variation in the axis.

<Composition of cellulose acylate solution B>
Cellulose acetate with a substitution degree of 2.93 100.0 parts by mass Methylene chloride (first solvent) 517.6 parts by mass Methanol (second solvent) 77.3 parts by mass Silica particles with an average particle size of 16 nm 0.13 parts by mass (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.)
Compound for reducing optical anisotropy (A-19) 11.7 parts by weight Wavelength dispersion modifier (UV-102) 1.2 parts by weight Citrate ester 0.01 parts by weight

Example 1-3
(Preparation of cellulose acylate film 103)
A cellulose acylate film 103 was produced in the same manner except that the cellulose acylate solution was changed to the following composition in Example 1-1. Table 1 shows Re and Rth of the obtained film, variation in the width direction thereof, and variation in the axis.

<Composition of cellulose acylate solution C>
Cellulose acetate having a substitution degree of 2.86 100.0 parts by mass Methylene chloride (first solvent) 517.6 parts by mass Methanol (second solvent) 77.3 parts by mass Silica particles having an average particle diameter of 16 nm 0.13 parts by mass (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.)
The compound which reduces the following optical anisotropy 12.0 mass parts Citric acid ester 0.01 mass part

  Compounds that reduce optical anisotropy

Comparative Example 1-1
(Preparation of cellulose acylate film 112)
A cellulose acylate film 112 was produced in the same manner as in Example 1-1 except that the cellulose acylate solution was changed to the following composition and the roll width was 1360 mm. Table 1 shows Re and Rth of the obtained film, variation in the width direction thereof, and variation in the axis.

<Composition of cellulose acylate solution D>
Cellulose acetate having a substitution degree of 2.87 100 parts by weight Triphenyl phosphate (plasticizer) 8.8 parts by weight Biphenyl diphenyl phosphate (plasticizer) 4.0 parts by weight Methylene chloride (first solvent) 293 parts by weight Methanol (second solvent) 71 parts by mass 1-butanol (third solvent) 1.5 parts by mass Silica particles having an average particle diameter of 16 nm 0.8 parts by mass (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.)

Examples 1-4 to 1-11, Comparative Example 1-2
Cellulose acylate films 104 to 111 and 113 were produced in the same manner as in Example 1 except that the cellulose acylate solution, roll width, roll length, and production conditions were changed as shown in Table 1. Table 1 shows Re and Rth of the obtained film, variation in the width direction thereof, and variation in the axis.

Example 1-12
(Preparation of cellulose acylate film 114)
A cellulose acylate film 114 was produced in the same manner except that the cellulose acylate solution was changed to the following composition in Example 1-1. Table 1 shows Re and Rth of the obtained film, variation in the width direction thereof, and variation in the axis.

<Cellulose acylate solution E composition>
Cellulose acetate having a substitution degree of 2.86 100.0 parts by mass Methylene chloride (first solvent) 517.6 parts by mass Methanol (second solvent) 77.3 parts by mass Silica particles having an average particle diameter of 16 nm 0.13 parts by mass (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.)
Styrene oligomer 2.0 parts by mass Citric acid ester 0.01 parts by mass

Example 1-13
(Preparation of cellulose acylate film 115)
A cellulose acylate film 115 was produced in the same manner except that the cellulose acylate solution was changed to the following composition in Example 1-1. Table 1 shows Re and Rth of the obtained film, variation in the width direction thereof, and variation in the axis.

<Composition of cellulose acylate solution F>
Cellulose acetate having a substitution degree of 2.86 100.0 parts by mass Methylene chloride (first solvent) 517.6 parts by mass Methanol (second solvent) 77.3 parts by mass Silica particles having an average particle diameter of 16 nm 0.13 parts by mass (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.)
Acrylic polyol 20.0 parts by mass Citric acid ester 0.01 parts by mass

[Preparation of polarizing plate]
Example 2-1
(Preparation of polarizing plate 101X)
The cellulose acylate film 101 was continuously passed through a 1.5 mol / L sodium hydroxide aqueous solution and immersed at 55 ° C. for 2 minutes. It wash | cleaned in the room temperature water-washing tub, and neutralized using the 0.1 mol / L sulfuric acid at 30 degreeC. Again, it was washed in a water bath at room temperature and further dried with hot air at 100 ° C. In this way, the surface of the cellulose acylate film 101 was saponified.
Subsequently, a roll-shaped polyvinyl alcohol film having a thickness of 80 μm was continuously stretched 5 times in an iodine aqueous solution and dried to obtain a polarizing film having a thickness of 20 μm. Using a 3% aqueous solution of polyvinyl alcohol (Kuraray PVA-117H) as an adhesive, two saponified cellulose acylate films 101 are prepared and bonded with a roll-to-roll with a polarizing film in between. A polarizing plate 101X protected by the rate film 101 was obtained.

Examples 2-2 to 2-13, Comparative Examples 2-1 and 2-2
Polarizing plates 102X to 115X using the respective cellulose acylate films were produced in the same manner as in Example 2-1, except that any of the cellulose acylate films 102 to 115 was used instead of the cellulose acylate film 101. .

[Evaluation of mounting on panel]
Example 3-1.
The polarizing plate 101X of the present invention was mounted on a panel of a liquid crystal display device and evaluated.
[IPS mode]
<Polarizing plate for IPS liquid crystal cell>
A polyester film having a dimensional change rate (MD / TD) of 1.15 at 165 degrees is adhered to both sides of a polycarbonate having a length of 100 m, a width of 180 mm, a thickness of 80 μm and a Re of 0 nm via an acrylic adhesive layer, and a roll. The polyester film was peeled off after shrinking the polycarbonate by treatment in a room temperature atmosphere with a roll speed ratio of 0.97 and a roll temperature of 165 ° C. using a stretching machine. This retardation plate was stretched 1.1 times in the width direction under an atmosphere of 163 degrees to obtain an optical compensation film Z1.
Using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments Co., Ltd.), the light incident angle dependency of Re was measured, and when these optical characteristics were calculated, Re was 270 nm,
It was confirmed that Nz was 0.5 and the slow axis was in a direction perpendicular to the longitudinal direction.
A polarizing plate-integrated optical compensation film 101Z1 was produced by pasting on one side of the polarizing plate 101X of the present invention so that the slow axis of the optical compensation film Z1 and the absorption axis of the polarizing plate coincide.

<Production of IPS mode liquid crystal cell>
On one glass substrate, electrodes were arranged so that the distance between adjacent electrodes was 20 μm, and a polyimide film was provided as an alignment film thereon, and a rubbing treatment was performed. A polyimide film was provided on one surface of a separately prepared glass substrate, and a rubbing treatment was performed to obtain an alignment film. The two glass substrates are stacked and bonded so that the alignment films face each other, the distance between the substrates (gap; d) is 3.9 μm, and the rubbing directions of the two glass substrates are parallel. A nematic liquid crystal composition having a refractive index anisotropy (Δn) of 0.0769 and a dielectric anisotropy (Δε) of 4.5 was enclosed. The value of d · Δn of the liquid crystal layer was 300 nm.
The polarizing plate of the present invention is attached to the light source side of the liquid crystal cell with an adhesive so that the slow axis of the liquid crystal cell coincides with the absorption axis of the polarizing plate, and the opposite polarizing plate and absorption axis are on the opposite side of the liquid crystal cell. An IPS liquid crystal display device was prepared by attaching the optical compensation film side of the polarizing plate-integrated optical compensation film 101Z1 to the liquid crystal cell side so as to be orthogonal to each other and sticking with an adhesive.

[VA mode]
(Optical compensation film for VA)
Using the cellulose acylate film 101, an optical compensation film sample was produced according to the method described in Example 1 of JP-A No. 2003-315541. Synthesis from 2,2′-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl (TFMB) A solution prepared by adding 25 wt% of a polyimide having a weight average molecular weight (Mw) of 70,000 and Δn of about 0.04 to cyclohexanone as a solvent was applied to the cellulose acylate film 101. Then, after heat treatment at 100 ° C. for 10 minutes, 15% longitudinal uniaxial stretching was performed at 160 ° C. to obtain an optical compensation film in which a 6 μm-thick polyimide film was applied to the transparent film of the present invention. The optical properties of this optical compensation film were Re = 72 nm, Rth = 220 nm, the misalignment angle of the orientation axis was within ± 0.3 degrees, and an optical compensation film Z2 having a birefringent layer of nx>ny> nz.

<Production of VA liquid crystal cell>
1% by weight of octadecyldimethylammonium chloride (coupling agent) was added to a 3% by weight aqueous solution of polyvinyl alcohol. This was spin-coated on a glass substrate with an ITO electrode and heat-treated at 160 ° C. to form a vertical alignment film. Two glass substrates face each other, and a liquid crystal compound (Δn: 0.06) mainly composed of an ester group and an ethane group is injected into the cell gap, so that a product of Δn and d is 300 nm. A cell was produced.
The side of the optical compensation film Z2 on which the polyimide film was not applied was subjected to alkali saponification treatment and adhered to the polarizer with a polyvinyl alcohol-based adhesive, thereby being directly bonded to the polarizer. Further, Fujitac TD80UF (manufactured by Fuji Photo Film Co., Ltd.) subjected to alkali saponification treatment was similarly bonded to the polarizer as a protective film opposite to the optical compensation film Z2 with the polarizer interposed therebetween. At this time, a polarizing plate integrated optical compensation film 101Z2 was obtained so that the slow axis of the optical compensation film and the absorption axis of the polarizing plate were orthogonal to each other. The polarizing plate integrated optical compensation film 101Z2 was bonded to the VA liquid crystal panel with an adhesive so that the optical compensation film side was the liquid crystal cell side. In addition, on the opposite side of the liquid crystal cell, only the polarizing plate (polarizing plate with Fujitac TD80UF as protective films on both sides) is bonded to the VA liquid crystal panel via an adhesive so that the absorption axes of the polarizing plates are orthogonal to each other. A liquid crystal display device was created.

(Panel evaluation)
<Evaluation of viewing angle characteristics and display unevenness of manufactured liquid crystal display device>
The viewing angle dependence of the transmittance of the prepared liquid crystal display device was measured. The suppression angle was measured from the front to the diagonal direction up to 80 ° every 10 °, and the azimuth angle was measured up to 360 ° every 10 ° on the basis of the horizontal right direction (0 °). It was found that the luminance at the time of black display increased as the angle of suppression increased from the front direction, and the leaked light transmittance also increased and took a maximum value near the angle of suppression of 70 °. It was also found that the contrast deteriorates as the black display transmittance increases. Therefore, the viewing angle characteristics were evaluated based on the maximum values of the black display transmittance at the front and the leaked light transmittance at an angle of 60 °. Further, the level of unevenness was evaluated by observing a black display with a suppression angle of 60 °. Table 2 shows the evaluation results of the panel.

<Evaluation of display characteristics>
Evaluation of viewing angle characteristics ◎: Very little difference in viewing angle characteristics is good ○: Little difference in viewing angle characteristics ×: Large difference in viewing angle characteristics

Evaluation of display unevenness ◎: Very little unevenness ○: Very little unevenness △: Little unevenness ×: Somewhat unevenness XX: Large unevenness

Examples 3-2 to 3-13, Comparative Examples 3-1 and 3-2
<IPS polarizing plate for IPS liquid crystal cell> An IPS liquid crystal display using each polarizing plate in the same manner as in Example 3-1, except that any of polarizing plates 102X to 115X is used instead of the polarizing plate 101X. A device was made.
Further, each cellulose acylate film is used in the same manner as in Example 3-1, except that any of the cellulose acylate films 102 to 115 is used instead of the cellulose acylate film 101 in (VA optical compensation film). A VA liquid crystal display device was produced.
The results of panel evaluation as in Example 3-1 are shown in Table 2.

  From Table 2, the liquid crystal display device produced by using the film of the present invention with small optical anisotropy and small retardation variation has excellent viewing angle characteristics, small display unevenness, and excellent display performance. You can see that

Claims (22)

In the width direction of the transparent film, the in-plane retardation value (Rec) at the center of the film is 20 nm or less, and the absolute value of the thickness direction retardation value (Rthc) at the center of the film is 20 nm or less. A transparent film characterized by satisfying at least one of the conditions (a1), (a2), and (a3).
(A1) The absolute value of the difference between Rec and the in-plane retardation value (Ree) at the film edge is 1.5 nm or less.
(A2) The absolute value of the slope of the in-plane retardation value Re from the film edge to the film center in the width direction is 0.5 nm / m or less.
(A3) The standard deviation of the in-plane retardation value Re in the width direction is 0.25 nm or less. The transparent film according to claim 1, wherein at least one of the following conditions (a4), (a5), and (a6) is satisfied.
(A4) The absolute value of the difference between the Rthc and the film thickness direction retardation value (Rthe) at the film edge is 5 nm or less.
(A5) The absolute value of the gradient of the film thickness direction retardation value Rth from the film edge to the film center in the width direction is 5 nm / m or less.
(A6) The standard deviation of the film thickness direction retardation value Rth in the width direction is 2.5 nm or less. The transparent film according to claim 1, wherein Re of the film satisfies the following condition (a7).
(a7) 0.0001> sin ² (2θ) sin ² (πRe / λ)
(Θ is the angle (radian) formed between the slow axis direction in the film plane and the film forming direction (straight direction of the film), λ is the wavelength of light (nm) when measuring the three-dimensional refractive index, and π is a circle. (Period.)   4. The transparent film according to claim 1, wherein the transparent film has a width of 1000 mm to 5000 mm and a length of 100 m to 10000 m.   Cellulose acylate having an acyl substitution degree of 2.85 to 3.00 contains at least one compound that lowers Re and Rth and 0.01 to 30% by weight based on the solid content of cellulose acylate. The transparent film in any one of Claims 1-4.   6. The transparent film according to claim 5, wherein the acyl substituent of cellulose acylate is an acetyl group, the total degree of substitution is 2.85 to 2.95, and the average degree of polymerization is 180 to 550. .   6. The transparent film according to claim 5, wherein the acyl substituent comprises at least two of acetyl group / propionyl group / butanoyl group. And a compound that reduces Re and Rth and a compound that reduces | Re ₍₄₀₀₎ -Re ₍₇₀₀₎ | or | Rth ₍₄₀₀₎ -Rth ₍₇₀₀₎ | The transparent film according to any one of claims 1 to 7.
(Where Re ₍ λ ₎ is the Re value at the wavelength λnm and Rth ₍ λ ₎ is the Rth value at the wavelength λnm)   9. The transparent film according to claim 8, wherein at least one of the compounds for reducing Re and Rth has negative intrinsic birefringence.   The transparent film according to claim 8 or 9, wherein at least one of the compounds for reducing Re and Rth is a styrene oligomer and / or a benzyl methacrylate oligomer.   The film thickness of a film is 20-300 micrometers, The transparent film in any one of Claims 1-10 characterized by the above-mentioned.   It is a manufacturing method of the transparent film in any one of Claims 1-11, Comprising: Based on the retardation value obtained by the optical characteristic measurement system in a manufacturing line, tenter conditions, drying conditions, and the amount of additives during production A method for producing a transparent film, comprising adjusting at least one of polymer types.   The method for producing a transparent film according to claim 12, wherein the polymer is cellulose acylate, and an average degree of acetylation of cellulose acylate is adjusted during production.   The method for producing a transparent film according to claim 13, wherein the average degree of acetylation of the cellulose acylate is adjusted by mixing at least two types of cellulose acylates having different degrees of acetylation.   An optical compensation film having an optically anisotropic layer having Re of 0 to 200 nm and | Rth | of 0 to 400 nm on the transparent film according to claim 1.   The optical compensation film according to claim 15, wherein the optically anisotropic layer contains a discotic liquid crystal layer.   The optical compensation film according to claim 15, wherein the optically anisotropic layer contains a rod-like liquid crystal layer.   The optical compensation film according to claim 15, wherein the optically anisotropic layer contains a polymer film.   A polarizing plate comprising at least one of the transparent film according to claim 1 or the optical compensation film according to claim 15 as a protective film for a polarizer.   The polarizing plate according to claim 19, wherein at least one layer of a hard coat layer, an antiglare layer, an antireflection layer and an antistatic layer is provided on the surface.   The transparent film according to any one of claims 1 to 11, the optical compensation film according to any one of claims 15 to 18, and at least one polarizing plate according to any one of claims 19 or 20 is used. A characteristic liquid crystal display device.   The transparent film according to any one of claims 1 to 11, the optical compensation film according to any one of claims 15 to 18, and at least one polarizing plate according to any one of claims 19 or 20 is used. Characteristic VA or IPS liquid crystal display device.