JP2009198658A - Retardation film, method for producing the same, polarizing plate and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a retardation film which ensures a small scattered light intensity difference and hardly reduces frontal contrast under a wet heat cycle test when used in a liquid crystal display, to provide a method for producing the retardation film, and to provide a polarizing plate and a liquid crystal display using the retardation film. <P>SOLUTION: The retardation film is formed by stacking at least one layer containing a (meth)acrylic resin and at least one layer containing a positive-birefringent resin, wherein, in scattered light intensity measurement of the film on incident light 90° of scattered light profile of a goniophotometer, when scattered light intensity in a position of 130° from a light source is detected, a scattered light intensity difference between the case where a slow axis of the film is horizontally set on a sample stand and the case where the slow axis is perpendicularly set is ≤0.05. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a retardation film, a method for producing a retardation film, a polarizing plate, and a liquid crystal display device. More specifically, the difference in scattered light intensity is small, and there is little decrease in contrast due to a wet heat cycle test when used in a liquid crystal display device. The present invention relates to a retardation film.

A phase difference film for optical compensation is used in a liquid crystal display device. For example, a liquid crystal display film, a liquid crystal layer formed on a thermoplastic resin film, or a plurality of different resins are used. Laminated films are used. As an example of laminating a plurality of resins, a film in which a positive birefringent resin layer is laminated on a base film has been proposed. As this base film, various resins can be considered. For example, Patent Documents 1 and 2 propose to laminate on an acrylic resin. However, when a retardation film is prepared using a general acrylic PMMA (polymethylmethacrylate) or a resin described therein and mounted on a liquid crystal display device, there is a problem that the contrast is greatly reduced by a wet heat cycle test. I found out that
JP 2004-212971 A JP-A-2005-55601

  Accordingly, it is an object of the present invention to provide a retardation film having a small difference in scattered light intensity and having little reduction in contrast by a wet heat cycle test when used in a liquid crystal display device. Furthermore, it is providing the manufacturing method of this retardation film, the polarizing plate using this retardation film, and a liquid crystal display device.

  The above object of the present invention is achieved by the following configurations.

  1. A retardation film formed by laminating at least one layer including a (meth) acrylic resin layer and a layer including a positive birefringent resin, and having a 90 ° incident light of a scattered light profile of a goniophotometer. In the scattered light intensity measurement of the film, when detecting the scattered light intensity at a position of 130 ° from the light source, the difference in scattered light intensity between the case where the film slow axis is horizontally installed on the sample stage and the case where the film is vertically installed, A retardation film characterized by being 0.05 or less.

  2. 2. The retardation film as described in 1 above, wherein the (meth) acrylic resin has a lactone ring structure.

  3. 3. The retardation film as described in 2 above, wherein the lactone ring structure is a lactone ring structure represented by the following general formula (1).

[Wherein R ¹ , R ² and R ³ independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms; the organic residue may contain an oxygen atom]
4). 2. The retardation film as described in 1 above, wherein the positive birefringent resin is at least one resin selected from polyether ketone, polyamide, polyester, polyimide, polyamideimide and polyesterimide.

  5). A polarizing plate comprising the retardation film according to any one of 1 to 4 on at least one surface.

  6). 6. A liquid crystal display device comprising the polarizing plate according to 5 above on at least one surface of a liquid crystal cell.

  7. On the film containing the (meth) acrylic resin described in any one of 1 to 3 above, a laminated film obtained by coating the layer containing the positive birefringent resin described in 4 above, at 120 ° C. A method for producing a retardation film, wherein the film is stretched in at least one direction.

  According to the present invention, it is possible to provide a retardation film that has a small difference in scattered light intensity and that has little reduction in contrast when used in a liquid crystal display device, and is incorporated in a polarizing plate and a liquid crystal display device. It is possible to provide a stable and high front contrast.

  The best mode for carrying out the present invention will be described in detail below, but the present invention is not limited thereto.

  The retardation film of the present invention is a retardation film formed by laminating at least one layer containing a (meth) acrylic resin and a layer containing a positive birefringent resin, and is scattered by a goniophotometer. In the measurement of the scattered light intensity of a film having an incident light of 90 ° in the light profile, when detecting the scattered light intensity at a position of 130 ° from the light source, the film slow axis was set vertically with respect to the case where the film was placed on the sample stage. In this case, the difference in scattered light intensity is 0.05 or less, the difference in scattered light intensity is small due to the configuration, and the retardation film has a small decrease in front contrast by a wet heat cycle test when used in a liquid crystal display device. The object of the present invention to obtain the above can be realized.

  The wet heat cycle test referred to in the present invention is a test for monitoring a change in optical characteristics during storage of a retardation film over time. The procedure of the wet heat cycle test is not particularly limited. For example, a liquid crystal display device having a sample film as a member in an environment having a humidity of 80% and a temperature of 60 ° C. for 1 hour, and then in a temperature of −20 ° C. for 1 hour. It is possible to evaluate the durability of the retardation film by measuring the following front contrast using a liquid crystal display device in which this is repeated for 100 to 300 cycles. The environmental test is performed using a commercially available thermostatic and humidity chamber that can automatically control the temperature and humidity.

  The front contrast is evaluated by incorporating a polarizing plate equipped with the retardation film according to the present invention into a liquid crystal display device and using EZ-Contrast 160D manufactured by ELDIM in an environment of 23 ° C. and 55% RH. The luminance from the normal direction of the display screen of the display and the black display can be measured, and the ratio can be obtained as the front contrast.

Front contrast = (brightness of white display measured from normal direction of display device) / (brightness of black display measured from normal direction of display device)
As a result of intensive studies on the above problems, the present inventors presume the mechanism for causing a decrease in front contrast by a wet heat cycle test in a retardation film as follows.

  1. When the retardation film is placed under high temperature and high humidity, the voids formed by stretching contain moisture and swell.

  2. It is cooled rapidly in the swollen state, and fine ice is generated between the molecules, expanding the voids.

  3. When returned to high temperature and high humidity again, ice melts but voids remain.

  4). When the voids are formed, it becomes easier to contain water, and the voids become larger by the wet heat cycle test, which causes a decrease in contrast.

  The inventors of the present invention further studied and assumed that the large gap can be detected by the scattered light intensity difference. As a result, it has been found that if the generation of voids due to stretching is suppressed and the difference in scattered light intensity is reduced, a decrease in front contrast due to a wet heat cycle test can be prevented. The present inventors have used a (meth) acrylic resin, particularly a (meth) acrylic resin having a lactone ring structure, as a means for suppressing the generation of voids due to stretching, and stretching at a high temperature of 120 ° C. or higher. Is found to be effective.

  Hereinafter, the present invention will be described in detail.

<Scattered light measured by goniophotometer>
The retardation film of the present invention is characterized in that the scattered light measured by a goniophotometer is in a certain range even when it is stretched.

  In order to improve the front contrast, it has been said that it is necessary to reduce the haze of the film. However, it is not always possible to improve the front contrast only by reducing the haze corresponding to the straight light. It has been found that it is necessary to eliminate isotropic scattering. Anisotropic scattering refers to the difference in scattered light intensity between the slow axis direction of the film and the direction orthogonal thereto. This anisotropic scattering is measured with a goniophotometer.

(Anisotropic scattering measurement device)
FIG. 1 shows an outline of a goniophotometer (model: GP-1-3D, manufactured by Optec Corporation). G1. Light source lamp, G2. Spectrometer, G3. Sample stage (also called stage), G4. Sample (not shown), G5. It is a light receiving part.

  The light source uses a 12V50W halogen bulb, and the light receiving section uses a photomultiplier tube (Photomaru Hamamatsu Photonics R636-10).

  (A) shows the arrangement of a light source lamp, a spectroscope, a sample stage (stage), and an integrating sphere for measuring light intensity at the time of reference measurement for measuring reference light or transmittance measurement.

  (B) shows the arrangement of the light source lamp, the spectroscope, the sample stage, and the integrating sphere when the measurement sample is placed on the sample stage and the reflectance is measured.

  The sample stage is usually a measurement sample vertical hanging type, and the measurement sample is fixed with a clamp, and the lower part of the stage is an angle indexing rotary table. The transmittance is changed by changing the angle between the sample surface and the incident surface. It is a structure that can measure the reflectance.

  The anisotropic scattered light intensity according to the present invention can be measured by the arrangement (a). That is, the measurement of the scattered light intensity of a film having an incident light of 90 ° in the scattered light profile of the goniophotometer refers to the scattered light intensity when light is applied perpendicularly to the sample from the light source of the goniophotometer.

  When measuring the scattered light intensity at a position of 130 ° from the light source, the direction connecting the normal direction of the light source, the observation point of the sample, and the integrating sphere shown in FIG. This is the scattered light intensity measured when the angle θ formed by is 130 °.

  In the present invention, in the measurement of scattered light intensity at a position where θ is 130 °, the difference in scattered light intensity between the case where the film slow axis is horizontally installed on the sample stage and the case where the film is vertically installed is 0.05 or less. It is characterized by being.

  In order to satisfy the horizontal and vertical conditions, a normal level can be used.

  Various angles can be selected as θ, but in the present invention, it is set to 130 °, which has the highest correlation with the front contrast, which is the final evaluation as a liquid crystal display device.

  When horizontal and vertical, each scattered light intensity is 0.01 to 0.25, preferably 0.20 or less, and more preferably 0.10 or less.

  The smaller the scattered light intensity difference, the better.

  In order to achieve the scattered light intensity of the present invention, the retardation film of the present invention comprises at least one layer including a (meth) acrylic resin layer and a layer including a positive birefringent resin. It is necessary to be a laminated film.

<(Meth) acrylic resin>
Although it does not specifically limit as (meth) acrylic-type resin, For example, poly (meth) acrylic acid ester, such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymer, methyl methacrylate- (meth) Acrylic ester copolymer, methyl methacrylate-acrylic ester- (meth) acrylic acid copolymer, (meth) methyl acrylate-styrene copolymer (MS resin, etc.), heavy polymer having alicyclic hydrocarbon group Examples thereof include a compound (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate- (meth) acrylate norbornyl copolymer, etc.) and the like. Preferably, poly (meth) acrylic acid C1-6 alkyl such as poly (meth) acrylic acid methyl, more preferably methyl methacrylate is the main component (50-100% by mass, preferably 70-100% by mass). A methyl methacrylate resin is mentioned.

  Specific examples of the (meth) acrylic resin include (meth) acrylic resins having a ring structure in the molecule described in, for example, Acrypet VH and Acrypet VRL20A manufactured by Mitsubishi Rayon Co., Ltd., and JP-A-2004-70296. Examples of the resin include high Tg (meth) acrylic resins obtained by intramolecular crosslinking or intramolecular cyclization reaction.

<(Meth) acrylic resin with lactone ring structure>
The retardation film of the present invention preferably has a layer containing a (meth) acrylic resin having a lactone ring structure (hereinafter also referred to as a lactone ring-containing polymer), and the lactone ring structure is preferably represented by the following general formula (1 ).

[Wherein R ¹ , R ² and R ³ independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms; the organic residue may contain an oxygen atom]
Having a lactone ring structure.

  The content of the lactone ring structure represented by the general formula (1) in the structure of the lactone ring-containing polymer is preferably 5 to 90% by mass, more preferably 10 to 70% by mass, and still more preferably 10 to 60% by mass. %, Particularly preferably 10 to 50% by mass. Within this range, the obtained polymer is excellent in heat resistance, solvent resistance and surface hardness, which is preferable.

  The lactone ring-containing polymer may have a structure other than the lactone ring structure represented by the general formula (1). The structure other than the lactone ring structure represented by the general formula (1) is not particularly limited. For example, a (meth) acrylic acid ester described later as a method for producing a lactone ring-containing polymer and A polymer formed by polymerizing at least one monomer selected from the group consisting of a hydroxyl group-containing monomer, an unsaturated carboxylic acid, and a monomer represented by the following general formula (2): A combined structural unit (repeating structural unit) is preferred.

[Wherein, R ⁴ represents a hydrogen atom or a methyl group, X represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, an —OAc group, a —CN group, a —CO—R ⁵ group, or —CO —O—R ⁶ group, Ac represents an acetyl group, R ⁵ and R ⁶ represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms]
The content ratio of the structure other than the lactone ring structure represented by the general formula (1) in the structure of the lactone ring-containing polymer is a polymer structural unit (repeated structural unit) formed by polymerizing a (meth) acrylic acid ester. ) Is preferably 10 to 95% by mass, more preferably 10 to 90% by mass, still more preferably 40 to 90% by mass, particularly preferably 50 to 90% by mass, and polymerizes the hydroxy group-containing monomer. In the case of the polymer structural unit (repeating structural unit) formed in this manner, it is preferably 0 to 30% by mass, more preferably 0 to 20% by mass, still more preferably 0 to 15% by mass, and particularly preferably 0 to 10% by mass. It is. In the case of a polymer structural unit (repeating structural unit) formed by polymerizing an unsaturated carboxylic acid, it is preferably 0 to 30% by mass, more preferably 0 to 20% by mass, and still more preferably 0 to 15% by mass. Especially preferably, it is 0-10 mass%. Furthermore, in the case of a polymer structural unit (repeating structural unit) formed by polymerizing the monomer represented by the general formula (2), preferably 0 to 30% by mass, more preferably 0 to 20% by mass, More preferably, it is 0-15 mass%, Most preferably, it is 0-10 mass%.

  The method for producing the lactone ring-containing polymer is not particularly limited. For example, after the polymer (a) having a hydroxy group and an ester group in the molecular chain is obtained by a polymerization step, the obtained heavy polymer is obtained. It can be obtained by carrying out a lactone cyclization condensation step for introducing a lactone ring structure into the polymer by heat-treating the compound (a).

  In the polymerization step, for example, a polymer having a hydroxyl group and an ester group in the molecular chain is obtained by performing a polymerization reaction of a monomer component containing a monomer represented by the following general formula (3). It is done.

[Wherein, R ⁷ and R ⁸ each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms]
Examples of the monomer represented by the general formula (3) include methyl 2- (hydroxymethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate, isopropyl 2- (hydroxymethyl) acrylate, 2- ( Hydroxymethyl) n-butyl acrylate, 2- (hydroxymethyl) acrylate t-butyl and the like. These monomers may be used alone or in combination of two or more. Among these monomers, 2- (hydroxymethyl) methyl acrylate and 2- (hydroxymethyl) ethyl acrylate are preferable, and since the effect of improving heat resistance is high, methyl 2- (hydroxymethyl) acrylate Is particularly preferred.

  The content ratio of the monomer represented by the general formula (3) in the monomer component to be subjected to the polymerization step is preferably 5 to 90% by mass, more preferably 10 to 70% by mass, and still more preferably 10 to 60%. It is 10 mass%, Most preferably, it is 10-50 mass%. When the content ratio of the monomer represented by the general formula (3) is less than 5% by mass, the heat resistance, solvent resistance, and surface hardness of the obtained polymer may be lowered. On the contrary, when the content ratio of the monomer represented by the general formula (3) exceeds 90% by mass, gelation may occur in the polymerization process or the lactone cyclization condensation process, and the obtained polymer may be molded. May decrease.

  You may mix | blend monomers other than the monomer shown by the said General formula (3) with the monomer component with which it uses for a superposition | polymerization process. Such a monomer is not particularly limited, and examples thereof include (meth) acrylic acid esters, hydroxy group-containing monomers, unsaturated carboxylic acids, and the general formula (2). And monomers. These monomers may be used alone or in combination of two or more.

  The (meth) acrylic acid ester is not particularly limited as long as it is a (meth) acrylic acid ester other than the monomer represented by the general formula (3). For example, methyl acrylate, acrylic acid Acrylic esters such as ethyl, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, cyclohexyl acrylate, benzyl acrylate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, methacryl And methacrylic acid esters such as isobutyl acid, t-butyl methacrylate, cyclohexyl methacrylate, and benzyl methacrylate. These (meth) acrylic acid esters may be used alone or in combination of two or more. Among these (meth) acrylic acid esters, methyl methacrylate is particularly preferable because the obtained polymer has excellent heat resistance and transparency.

  When (meth) acrylic acid ester other than the monomer represented by the general formula (3) is used, the content ratio in the monomer component to be subjected to the polymerization step is sufficient to exert the effect of the present invention. The content is preferably 10 to 95% by mass, more preferably 10 to 90% by mass, still more preferably 40 to 90% by mass, and particularly preferably 50 to 90% by mass.

  The hydroxy group-containing monomer is not particularly limited as long as it is a hydroxy group-containing monomer other than the monomer represented by the general formula (3). For example, α-hydroxymethylstyrene, α-hydroxyethyl styrene, 2- (hydroxyalkyl) acrylic acid ester such as methyl 2- (hydroxyethyl) acrylate; 2- (hydroxyalkyl) acrylic acid such as 2- (hydroxyethyl) acrylic acid; . These hydroxy group-containing monomers may be used alone or in combination of two or more.

  When a hydroxy group-containing monomer other than the monomer represented by the general formula (3) is used, the content ratio in the monomer component to be subjected to the polymerization step is sufficient to exert the effect of the present invention. The content is preferably 0 to 30% by mass, more preferably 0 to 20% by mass, still more preferably 0 to 15% by mass, and particularly preferably 0 to 10% by mass.

  Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, crotonic acid, α-substituted acrylic acid, α-substituted methacrylic acid and the like. These unsaturated carboxylic acids may be used alone or in combination of two or more. Among these unsaturated carboxylic acids, acrylic acid and methacrylic acid are particularly preferable because the effects of the present invention are sufficiently exhibited.

  When using an unsaturated carboxylic acid, the content ratio in the monomer component to be subjected to the polymerization step is preferably 0 to 30% by mass, more preferably 0 to 20% by mass, in order to sufficiently exhibit the effects of the present invention. %, More preferably 0 to 15% by mass, particularly preferably 0 to 10% by mass.

  Examples of the monomer represented by the general formula (2) include styrene, α-methylstyrene, vinyl toluene, acrylonitrile, methyl vinyl ketone, ethylene, propylene, and vinyl acetate. These monomers may be used alone or in combination of two or more. Of these monomers, styrene and α-methylstyrene are particularly preferable because the effects of the present invention are sufficiently exhibited.

  When the monomer represented by the general formula (2) is used, the content ratio in the monomer component to be subjected to the polymerization step is preferably 0 to 30% by mass in order to sufficiently exhibit the effects of the present invention. More preferably, it is 0-20 mass%, More preferably, it is 0-15 mass%, Most preferably, it is 0-10 mass%.

  As a form of the polymerization reaction for polymerizing the monomer component to obtain a polymer having a hydroxy group and an ester group in the molecular chain, a polymerization form using a solvent is preferable, and solution polymerization is particularly preferable. .

  The polymerization temperature and the polymerization time vary depending on the type and ratio of the monomer used. For example, the polymerization temperature is preferably 0 to 150 ° C., the polymerization time is 0.5 to 20 hours, and more Preferably, the polymerization temperature is 80 to 140 ° C. and the polymerization time is 1 to 10 hours.

  In the case of a polymerization form using a solvent, the polymerization solvent is not particularly limited. For example, aromatic hydrocarbon solvents such as toluene, xylene, and ethylbenzene; ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone; tetrahydrofuran And ether solvents such as These solvents may be used alone or in combination of two or more. Moreover, since the residual volatile matter of the lactone ring containing polymer finally obtained will increase when the boiling point of a solvent is too high, the solvent whose boiling point is 50-200 degreeC is preferable.

  During the polymerization reaction, a polymerization initiator may be added as necessary. The polymerization initiator is not particularly limited. For example, cumene hydroperoxide, diisopropylbenzene hydroperoxide, di-t-butyl peroxide, lauroyl peroxide, benzoyl peroxide, t-butylperoxyisopropyl Organic peroxides such as carbonate and t-amylperoxy-2-ethylhexanoate; 2,2′-azobis (isobutyronitrile), 1,1′-azobis (cyclohexanecarbonitrile), 2,2 ′ -Azo compounds such as azobis (2,4-dimethylvaleronitrile); These polymerization initiators may be used alone or in combination of two or more. The amount of the polymerization initiator used is not particularly limited as long as it is appropriately set according to the combination of monomers and reaction conditions.

  When performing the polymerization, it is preferable to control the concentration of the polymer produced in the polymerization reaction mixture to be 50% by mass or less in order to suppress gelation of the reaction solution. Specifically, when the concentration of the polymer formed in the polymerization reaction mixture exceeds 50% by mass, it is preferable that the polymerization solvent is appropriately added to the polymerization reaction mixture and controlled to be 50% by mass or less. . The concentration of the polymer formed in the polymerization reaction mixture is more preferably 45% by mass or less, still more preferably 40% by mass or less. In addition, since productivity will fall when the density | concentration of the polymer produced | generated in the polymerization reaction mixture is too low, the density | concentration of the polymer produced | generated in the polymerization reaction mixture becomes like this. Preferably it is 10 mass% or more, More preferably, it is 20 mass%. That's it.

  The form in which the polymerization solvent is appropriately added to the polymerization reaction mixture is not particularly limited, and for example, the polymerization solvent may be added continuously or the polymerization solvent may be added intermittently. By controlling the concentration of the polymer formed in the polymerization reaction mixture in this way, the gelation of the reaction solution can be more sufficiently suppressed, and in particular, to increase the lactone ring content and improve the heat resistance. Even when the ratio of the hydroxy group and the ester group in the molecular chain is increased, gelation can be sufficiently suppressed. The polymerization solvent to be added may be, for example, the same type of solvent used during the initial charging of the polymerization reaction or a different type of solvent, but the solvent used during the initial charging of the polymerization reaction. It is preferable to use the same type of solvent. Moreover, the polymerization solvent to be added may be only one kind of single solvent or two or more kinds of mixed solvents.

  The polymerization reaction mixture obtained when the above polymerization step is completed usually contains a solvent in addition to the obtained polymer, but it is necessary to completely remove the solvent and take out the polymer in a solid state. Rather, it is preferably introduced into the subsequent lactone cyclization condensation step in a state containing a solvent. If necessary, after taking out in a solid state, a solvent suitable for the subsequent lactone cyclization condensation step may be added again.

  The polymer obtained in the polymerization step is a polymer (a) having a hydroxy group and an ester group in the molecular chain, and the weight average molecular weight of the polymer (a) is preferably 1,000 to 2,000,000, more preferably 5,000 to 1,000,000, more preferably 10,000 to 500,000, particularly preferably 50,000 to 500,000. The polymer (a) obtained in the polymerization step is subjected to heat treatment in the subsequent lactone cyclization condensation step, whereby a lactone ring structure is introduced into the polymer to become a lactone ring-containing polymer.

  The weight average molecular weight is measured using gel permeation chromatography (GPC).

  The measurement conditions are as follows.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation) Mw = 100000 to 500 calibration curves with 13 samples were used. Thirteen samples are used at approximately equal intervals.

  The reaction for introducing a lactone ring structure into the polymer (a) is a reaction in which a hydroxy group and an ester group present in the molecular chain of the polymer (a) are cyclized and condensed to form a lactone ring structure by heating. The alcohol is by-produced by the cyclized condensation. By forming the lactone ring structure in the molecular chain of the polymer (in the main skeleton of the polymer), high heat resistance is imparted. If the reaction rate of the cyclization condensation reaction leading to the lactone ring structure is insufficient, the heat resistance will not be improved sufficiently, or a condensation reaction will occur during the molding due to the heat treatment during molding, and the resulting alcohol will be contained in the molded product. May exist as bubbles or silver streaks.

  The lactone ring-containing polymer obtained in the lactone cyclization condensation step preferably has a lactone ring structure represented by the general formula (1).

  The method for heat-treating the polymer (a) is not particularly limited, and a conventionally known method may be used. For example, you may heat-process the polymerization reaction mixture containing the solvent obtained by the superposition | polymerization process as it is. Or you may heat-process using a ring-closure catalyst as needed in presence of a solvent. Alternatively, the heat treatment can also be performed using a vacuum furnace for removing volatile components, a heating furnace equipped with a devolatilizer, a reaction apparatus, an extruder equipped with a devolatilizer, or the like.

  In carrying out the cyclization condensation reaction, in addition to the polymer (a), another thermoplastic resin may coexist. When performing the cyclization condensation reaction, if necessary, an esterification catalyst or a transesterification catalyst such as p-toluenesulfonic acid generally used as a catalyst for the cyclization condensation reaction may be used. Organic carboxylic acids such as propionic acid, benzoic acid, acrylic acid, and methacrylic acid may be used as a catalyst. Furthermore, as disclosed in, for example, JP-A-61-254608 and JP-A-61-261303, basic compounds, organic carboxylates, carbonates and the like may be used.

  Alternatively, an organophosphorus compound may be used as a catalyst for the cyclization condensation reaction. Examples of the organic phosphoric acid compounds that can be used include alkyl (aryl) phosphonous acids such as methyl phosphonous acid, ethyl phosphonous acid, and phenyl phosphonous acid (however, these are alkyl (aryl) which are tautomers. ) Which may be phosphinic acid) and their monoesters or diesters; dialkyl (aryl) phosphinic acids such as dimethylphosphinic acid, diethylphosphinic acid, diphenylphosphinic acid, phenylmethylphosphinic acid, phenylethylphosphinic acid and their Esters; alkyl (aryl) phosphonic acids such as methylphosphonic acid, ethylphosphonic acid, trifluoromethylphosphonic acid, phenylphosphonic acid and their monoesters or diesters; methylphosphinic acid, ethylphosphinic acid, phenol Alkyl (aryl) phosphinic acids such as phosphinic acid and esters thereof; methyl phosphite, ethyl phosphite, phenyl phosphite, dimethyl phosphite, diethyl phosphite, diphenyl phosphite, phosphorus phosphite Phosphorous acid monoester, diester or triester such as trimethyl phosphate, triethyl phosphite, triphenyl phosphite; methyl phosphate, ethyl phosphate, 2-ethylhexyl phosphate, octyl phosphate, isodecyl phosphate, phosphoric acid Lauryl, stearyl phosphate, isostearyl phosphate, phenyl phosphate, dimethyl phosphate, diethyl phosphate, di-2-ethylhexyl phosphate, diisodecyl phosphate, dilauryl phosphate, distearyl phosphate, diisostearyl phosphate, Diphenyl phosphate, trimethyl phosphate, triethyl phosphate, phosphorus Phosphoric monoesters, diesters or triesters such as triisodecyl, trilauryl phosphate, tristearyl phosphate, triisostearyl phosphate, triphenyl phosphate; methylphosphine, ethylphosphine, phenylphosphine, dimethylphosphine, diethylphosphine, diphenylphosphine Mono-, di- or tri-alkyl (aryl) phosphine such as trimethylphosphine, triethylphosphine, triphenylphosphine; methyldichlorophosphine, ethyldichlorophosphine, phenyldichlorophosphine, dimethylchlorophosphine, diethylchlorophosphine, diphenylchlorophosphine, etc. Alkyl (aryl) halogen phosphines; methyl phosphine oxide, ethyl phosphine oxide, phenyl phosphine oxide Sphin, dimethylphosphine oxide, diethylphosphine oxide, diphenylphosphine oxide, trimethylphosphine oxide, triethylphosphine oxide, triphenylphosphine oxide, mono-, di- or trialkyl (aryl) phosphine oxides; tetramethylphosphonium chloride, tetraethyl chloride And halogenated tetraalkyl (aryl) phosphoniums such as phosphonium and tetraphenylphosphonium chloride. These organic phosphorus compounds may be used alone or in combination of two or more. Among these organophosphorus compounds, since the catalytic activity is high and the colorability is low, alkyl (aryl) phosphonous acid, phosphorous acid monoester or diester, phosphoric acid monoester or diester, and alkyl (aryl) phosphonic acid Preferably, alkyl (aryl) phosphonous acid, phosphorous acid monoester or diester, phosphoric acid monoester or diester is more preferable, and alkyl (aryl) phosphonous acid, phosphoric acid monoester or diester is particularly preferable.

  Although the usage-amount of the catalyst used in the case of a cyclization condensation reaction is not specifically limited, For example, Preferably it is 0.001-5 mass% with respect to a polymer (a), More preferably, it is 0.01. -2.5 mass%, More preferably, it is 0.01-1 mass%, Most preferably, it is 0.05-0.5 mass%. When the amount of the catalyst used is less than 0.001% by mass, the reaction rate of the cyclization condensation reaction may not be sufficiently improved. On the other hand, when the amount of the catalyst used exceeds 5% by mass, the obtained polymer may be colored or the polymer may be cross-linked to make melt molding difficult.

  The addition timing of the catalyst is not particularly limited. For example, the catalyst may be added at the beginning of the reaction, may be added during the reaction, or may be added in both of them.

  It is preferable to carry out the cyclization condensation reaction in the presence of a solvent and to use a devolatilization step in combination with the cyclization condensation reaction. In this case, a mode in which the devolatilization step is used throughout the cyclization condensation reaction and a mode in which the devolatilization step is not used throughout the entire cyclization condensation reaction and are used only in a part of the process. In the method using the devolatilization step in combination, the alcohol produced as a by-product in the condensation cyclization reaction is forcibly devolatilized and removed, so that the equilibrium of the reaction is advantageous for the production side.

  The devolatilization process means a process of removing volatile components such as solvents and residual monomers and alcohol by-produced by a cyclization condensation reaction leading to a lactone ring structure under reduced pressure heating conditions as necessary. To do. If this removal treatment is insufficient, residual volatile components in the obtained polymer increase, and coloring may occur due to deterioration during molding, and molding defects such as bubbles and silver streaks may occur.

  In the case of using a devolatilization step throughout the cyclization condensation reaction, the apparatus to be used is not particularly limited. For example, in order to more effectively perform the present invention, a devolatilization step and devolatilization are performed. It is preferable to use a devolatilizer comprising a tank or an extruder with a vent, or a devolatilizer and an extruder arranged in series, and a devolatilizer comprising a heat exchanger and a devolatilizer or an extruder with a vent It is more preferable to use a machine.

  The reaction treatment temperature in the case of using a devolatilizer comprising a heat exchanger and a devolatilizer is preferably 150 to 350 ° C, more preferably 200 to 300 ° C. If the reaction treatment temperature is less than 150 ° C., the cyclization condensation reaction may be insufficient and the residual volatile matter may increase. Conversely, when the reaction treatment temperature exceeds 350 ° C., the obtained polymer may be colored or decomposed.

  The reaction treatment pressure when using a devolatilizer comprising a heat exchanger and a devolatilizer is preferably 931 to 1.33 hPa (700 to 1 mmHg), more preferably 798 to 66.5 hPa (600 to 50 mmHg). . When the reaction treatment pressure exceeds 931 hPa (700 mmHg), volatile components including alcohol may easily remain. Conversely, if the reaction treatment pressure is less than 1.33 hPa (1 mmHg), industrial implementation may be difficult.

  When using an extruder with a vent, one or a plurality of vents may be used, but it is preferable to have a plurality of vents.

  The reaction treatment temperature when using an extruder with a vent is preferably 150 to 350 ° C, more preferably 200 to 300 ° C. If the reaction treatment temperature is less than 150 ° C., the cyclization condensation reaction may be insufficient and the residual volatile matter may increase. Conversely, when the reaction treatment temperature exceeds 350 ° C., the obtained polymer may be colored or decomposed.

  The reaction treatment pressure when using an extruder with a vent is preferably 931 to 1.33 hPa (700 to 1 mmHg), more preferably 798 to 13.3 hPa (600 to 10 mmHg). When the reaction treatment pressure exceeds 931 hPa (700 mmHg), volatile components including alcohol may easily remain. Conversely, if the reaction treatment pressure is less than 1.33 hPa (1 mmHg), industrial implementation may be difficult.

  In the case of a form in which a devolatilization step is used throughout the cyclization condensation reaction, the physical properties of the lactone ring-containing polymer obtained may be deteriorated under severe heat treatment conditions, as will be described later. It is preferable to carry out by using an extruder with a vent etc. on the conditions as mild as possible.

  In the case where the devolatilization step is used in combination throughout the cyclization condensation reaction, the polymer (a) obtained in the polymerization step is preferably introduced into the cyclization condensation reaction device together with a solvent. Depending on the situation, it may be passed once again through a cyclocondensation reaction apparatus such as a vented extruder.

  You may perform the form used together only in a part of process, without using a devolatilization process over the whole process of cyclization condensation reaction. For example, the apparatus for producing the polymer (a) is further heated, and if necessary, a part of the devolatilization step is used together to advance the cyclization condensation reaction to some extent in advance, followed by the devolatilization step. Is a form in which a cyclization condensation reaction is simultaneously used to complete the reaction.

  In the form of using the devolatilization step throughout the cyclization condensation reaction described above, for example, when the polymer (a) is heat-treated at a high temperature of about 250 ° C. or higher using a twin-screw extruder. Depending on the thermal history, partial decomposition or the like may occur before the cyclization condensation reaction occurs, and the physical properties of the resulting lactone ring-containing polymer may deteriorate. Therefore, if the cyclization condensation reaction is allowed to proceed to some extent before the cyclization condensation reaction using the devolatilization process at the same time, the latter reaction conditions can be relaxed, and the physical properties of the resulting lactone ring-containing polymer deteriorated. Is preferable. As a particularly preferred form, for example, a form in which the devolatilization step is started after a lapse of time from the start of the cyclization condensation reaction, that is, a hydroxy group present in the molecular chain of the polymer (a) obtained in the polymerization step A form in which an ester group is preliminarily subjected to a cyclization condensation reaction to increase the cyclization condensation reaction rate to some extent and then a cyclization condensation reaction using a devolatilization step simultaneously is performed. Specifically, for example, a cyclization condensation reaction is allowed to proceed to a certain reaction rate in the presence of a solvent in advance using a kettle reactor, and then a reactor equipped with a devolatilizer, for example, heat exchange Preferred is a mode in which the cyclization condensation reaction is completed with a devolatilizer comprising a vessel and a devolatilization tank, an extruder with a vent, or the like. In particular, in the case of this form, it is more preferable that a catalyst for the cyclization condensation reaction is present.

  As described above, the hydroxy group and the ester group present in the molecular chain of the polymer (a) obtained in the polymerization step are preliminarily subjected to a cyclization condensation reaction to increase the cyclization condensation reaction rate to some extent, The method of carrying out the cyclization condensation reaction using the devolatilization step at the same time is a preferred mode for obtaining a lactone ring-containing polymer in the present invention. With this form, a lactone ring-containing polymer having a higher glass transition temperature, a higher cyclization condensation reaction rate, and excellent heat resistance can be obtained. In this case, as a measure of the cyclization condensation reaction rate, for example, the mass reduction rate in the range of 150 to 300 ° C. in the dynamic TG measurement shown in the examples is preferably 2% or less, more preferably 1.5% or less. More preferably, it is 1% or less.

  The reactor that can be employed in the cyclization condensation reaction performed in advance before the cyclization condensation reaction using the devolatilization process at the same time is not particularly limited. For example, an autoclave, a kettle reactor, a heat exchanger And a devolatilizer comprising a devolatilization tank, and a vented extruder suitable for a cyclization condensation reaction using a devolatilization step at the same time can also be used. Of these reactors, an autoclave and a kettle reactor are particularly preferable. However, even when using a reactor such as an extruder with a vent, autoclaves and kettles can be adjusted by adjusting the temperature conditions, barrel conditions, screw shape, screw operating conditions, etc. It is possible to carry out the cyclization condensation reaction in the same state as the reaction state in the type reactor.

  In the case of the cyclization condensation reaction carried out in advance before the cyclization condensation reaction using the devolatilization step at the same time, for example, a mixture containing the polymer (a) and the solvent obtained in the polymerization step is used as (i) a catalyst. And (ii) a method of performing a heat reaction without a catalyst, a method of performing the above (i) or (ii) under pressure, and the like.

  The “mixture containing the polymer (a) and the solvent” introduced into the cyclization condensation reaction in the lactone cyclization condensation step refers to the polymerization reaction mixture itself obtained in the polymerization step or the solvent once removed. It means a mixture obtained by re-adding a solvent suitable for the cyclization condensation reaction later.

  The solvent that can be re-added in the cyclization condensation reaction that is carried out in advance before the cyclization condensation reaction using the devolatilization step at the same time is not particularly limited. For example, aromatic carbonization such as toluene, xylene, ethylbenzene, etc. Hydrogens; ketones such as methyl ethyl ketone and methyl isobutyl ketone; chloroform, dimethyl sulfoxide, tetrahydrofuran; and the like. These solvents may be used alone or in combination of two or more. It is preferable to use the same type of solvent as that used in the polymerization step.

  Examples of the catalyst to be added in the method (i) include commonly used esterification catalysts such as p-toluenesulfonic acid or transesterification catalysts, basic compounds, organic carboxylates, and carbonates. In the invention, it is preferable to use the aforementioned organophosphorus compound. The addition timing of the catalyst is not particularly limited. For example, the catalyst may be added at the beginning of the reaction, may be added during the reaction, or may be added in both of them. The addition amount of the catalyst is not particularly limited, but for example, is preferably 0.001 to 5% by mass, more preferably 0.01 to 2.5% by mass with respect to the mass of the polymer (a). More preferably, it is 0.01-1 mass%, Most preferably, it is 0.05-0.5 mass%. Although the heating temperature and heating time of method (i) are not particularly limited, for example, the heating temperature is preferably room temperature to 180 ° C., more preferably 50 to 150 ° C., and the heating time is preferably 1 to 20 hours, more preferably 2 to 10 hours. If the heating temperature is less than room temperature or the heating time is less than 1 hour, the cyclization condensation reaction rate may be lowered. Conversely, if the heating temperature exceeds 180 ° C. or the heating time exceeds 20 hours, the resin may be colored or decomposed.

  In the method (ii), for example, the polymerization reaction mixture obtained in the polymerization step may be heated as it is using a pressure-resistant kettle reactor or the like. Although the heating temperature and heating time of method (ii) are not particularly limited, for example, the heating temperature is preferably 100 to 180 ° C, more preferably 100 to 150 ° C, and the heating time is preferably 1 to 20 hours, more preferably 2 to 10 hours. If the heating temperature is less than 100 ° C. or the heating time is less than 1 hour, the cyclization condensation reaction rate may decrease. Conversely, if the heating temperature exceeds 180 ° C. or the heating time exceeds 20 hours, the resin may be colored or decomposed.

  In any method, there is no problem even under pressure depending on conditions.

  In the case of the cyclization condensation reaction performed in advance before the cyclization condensation reaction using the devolatilization step at the same time, there is no problem even if part of the solvent volatilizes spontaneously during the reaction.

  The mass reduction rate in the range of 150 to 300 ° C. in the dynamic TG measurement at the end of the cyclization condensation reaction performed in advance before the cyclization condensation reaction simultaneously using the devolatilization step, that is, immediately before the start of the devolatilization step is Preferably it is 2% or less, More preferably, it is 1.5% or less, More preferably, it is 1% or less. When the mass reduction rate exceeds 2%, the cyclization condensation reaction rate does not rise to a sufficiently high level even if the cyclization condensation reaction is performed simultaneously with the devolatilization step, and the physical properties of the resulting lactone ring-containing polymer. May deteriorate. In addition, when performing said cyclization condensation reaction, in addition to a polymer (a), you may coexist other thermoplastic resins.

  The hydroxy group and the ester group present in the molecular chain of the polymer (a) obtained in the polymerization step are preliminarily subjected to a cyclization condensation reaction to increase the cyclization condensation reaction rate to some extent. In the case of a form in which a combined cyclization condensation reaction is carried out, a polymer obtained by a cyclization condensation reaction carried out in advance (a polymer in which at least a part of a hydroxy group and an ester group present in a molecular chain is subjected to a cyclization condensation reaction) And the solvent may be introduced into the cyclization condensation reaction using the devolatilization step at the same time, and if necessary, the polymer (at least a part of the hydroxy group and ester group present in the molecular chain is present). It may be introduced into a cyclization condensation reaction in which a devolatilization step is used at the same time after other treatments such as re-addition of a solvent after the cyclization condensation reaction polymer is isolated.

  The devolatilization step is not limited to being completed at the same time as the cyclization condensation reaction, and may be completed after a lapse of time from the completion of the cyclization condensation reaction.

  The weight average molecular weight of the lactone ring-containing polymer is preferably 1,000 to 2,000,000, more preferably 5,000 to 1,000,000, still more preferably 10,000 to 500,000, and particularly preferably 50,000 to 500,000.

  The lactone ring-containing polymer has a mass reduction rate in the range of 150 to 300 ° C. in dynamic TG measurement, preferably 1% or less, more preferably 0.5% or less, and still more preferably 0.3% or less.

  Since the lactone ring-containing polymer has a high cyclization condensation reaction rate, it is possible to avoid the disadvantage that bubbles and silver streaks enter the molded product after molding. Furthermore, since the lactone ring structure is sufficiently introduced into the polymer due to a high cyclization condensation reaction rate, the obtained lactone ring-containing polymer has sufficiently high heat resistance.

  When the lactone ring-containing polymer is a chloroform solution having a concentration of 15% by mass, the coloration degree (YI) is preferably 6 or less, more preferably 3 or less, still more preferably 2 or less, and particularly preferably 1 or less. . If the degree of coloring (YI) exceeds 6, transparency may be impaired by coloring, and it may not be used for the intended purpose.

  The lactone ring-containing polymer has a 5% mass reduction temperature in thermal mass spectrometry (TG) of preferably 330 ° C. or higher, more preferably 350 ° C. or higher, and still more preferably 360 ° C. or higher. The 5% mass reduction temperature in thermal mass spectrometry (TG) is an index of thermal stability, and if it is less than 330 ° C., sufficient thermal stability may not be exhibited.

  The lactone ring-containing polymer has a glass transition temperature (Tg) of preferably 115 ° C. or higher, more preferably 125 ° C. or higher, still more preferably 130 ° C. or higher, and particularly preferably 140 ° C. or higher.

  The total amount of residual volatile components contained in the lactone ring-containing polymer is preferably 1500 ppm or less, more preferably 1,000 ppm or less. If the total amount of residual volatile components exceeds 1,500 ppm, it may be colored due to alteration during molding, foaming, or molding defects such as silver streak.

  The lactone ring-containing polymer has a total light transmittance of 85% or more, more preferably 88% or more, and still more preferably measured by a method based on ASTM-D-1003 for a molded product obtained by injection molding. 90% or more. The total light transmittance is an index of transparency, and if it is less than 85%, the transparency is lowered and it may not be used for the intended purpose.

  In the present invention, a layer containing a (meth) acrylic resin, preferably a layer containing a (meth) acrylic resin having a lactone ring structure (a layer containing a lactone ring-containing polymer) is a thermoplastic resin film. preferable.

  The content ratio of the (meth) acrylic resin or the lactone ring-containing polymer in the thermoplastic resin film is preferably 50 to 100% by mass, more preferably 60 to 100% by mass, still more preferably 70 to 100% by mass, particularly Preferably it is 80-100 mass%. When the content ratio of the (meth) acrylic resin or the lactone ring-containing polymer in the thermoplastic resin film is less than 50% by mass, the effects of the present invention may not be sufficiently exhibited.

  The thermoplastic resin film containing a (meth) acrylic resin or a lactone ring-containing polymer as a main component has a polymer other than the (meth) acrylic resin or the lactone ring-containing polymer as the other component (hereinafter, “ It may be referred to as “other polymer”. Examples of other polymers include olefin polymers such as polyethylene, polypropylene, ethylene-propylene copolymer, poly (4-methyl-1-pentene); halogens such as vinyl chloride, vinylidene chloride, and chlorinated vinyl resins. Acrylic polymers such as polymethyl methacrylate; Styrene polymers such as polystyrene, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene block copolymer Polyesters such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate; polyamides such as nylon 6, nylon 66 and nylon 610; polyacetal; polycarbonate; polyphenylene oxide; Sulfides; polyetheretherketone; polysulfones; polyethersulfones; polyoxyethylene benzylidene alkylene; polyamideimide; polybutadiene rubber, rubber-like polymer such as ABS resin or ASA resin containing an acrylic rubber; and the like.

  The content of the other polymer in the thermoplastic resin film is preferably 0 to 50% by mass, more preferably 0 to 40% by mass, still more preferably 0 to 30% by mass, and particularly preferably 0 to 20% by mass. .

  The thermoplastic resin film containing a (meth) acrylic resin or a lactone ring-containing polymer as a main component may contain various additives. Examples of additives include antioxidants such as hindered phenols, phosphorus, and sulfur; stabilizers such as light stabilizers, weather stabilizers, and heat stabilizers; reinforcing materials such as glass fibers and carbon fibers; phenyls UV absorbers such as salicylate, (2,2′-hydroxy-5-methylphenyl) benzotriazole, 2-hydroxybenzophenone; near infrared absorbers; tris (dibromopropyl) phosphate, triallyl phosphate, antimony oxide, etc. Flame retardants; Antistatic agents such as anionic, cationic and nonionic surfactants; Colorants such as inorganic pigments, organic pigments and dyes; Organic fillers and inorganic fillers; Resin modifiers; Organic fillers and inorganic fillers Agents, plasticizers, lubricants, antistatic agents, flame retardants, and the like.

  The content of the additive in the thermoplastic resin film containing a (meth) acrylic resin or a lactone ring-containing polymer as a main component is preferably 0 to 5% by mass, more preferably 0 to 2% by mass, and still more preferably. Is 0 to 0.5 mass%.

  Although it does not specifically limit as a manufacturing method of the thermoplastic resin film which has a (meth) acrylic resin or a lactone ring containing polymer as a main component, For example, (meth) acrylic resin or lactone ring containing A polymer and other polymers, additives, and the like are sufficiently mixed by a conventionally known mixing method to obtain a thermoplastic resin composition in advance, and then this can be formed into a film. Alternatively, a (meth) acrylic resin or a lactone ring-containing polymer and other polymers and additives are mixed in separate solutions to form a uniform mixed solution, and then formed into a film. Good.

  First, in order to produce a thermoplastic resin composition, for example, the above film raw material is pre-blended with a conventionally known mixer such as an omni mixer, and then the obtained mixture is extrusion kneaded. In this case, the mixer used for extrusion kneading is not particularly limited. For example, a conventionally known mixer such as an extruder such as a single screw extruder or a twin screw extruder or a pressure kneader can be used. .

  Examples of the film forming method include conventionally known film forming methods such as a solution casting method (solution casting method), a melt extrusion method, a calendar method, and a compression molding method. Among these film forming methods, the solution casting method (solution casting method) and the melt extrusion method are preferable.

  Examples of the solvent used in the solution casting method (solution casting method) include aromatic hydrocarbons such as benzene, toluene and xylene; aliphatic hydrocarbons such as cyclohexane and decalin; esters such as ethyl acetate and butyl acetate Ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; alcohols such as methanol, ethanol, isopropanol, butanol, isobutanol, methyl cellosolve, ethyl cellosolve and butyl cellosolve; ethers such as tetrahydrofuran and dioxane; dichloromethane, Halogenated hydrocarbons such as chloroform and carbon tetrachloride; dimethylformamide; dimethyl sulfoxide; These solvents may be used alone or in combination of two or more.

  Examples of the apparatus for performing the solution casting method (solution casting method) include a drum casting machine, a band casting machine, and a spin coater.

  Examples of the melt extrusion method include a T-die method and an inflation method, and the molding temperature at that time is preferably 150 to 350 ° C., more preferably 200 to 300 ° C.

  When forming a film by the T-die method, a roll-shaped film can be obtained by attaching a T-die to the tip of a known single-screw extruder or twin-screw extruder and winding the film extruded into a film. it can. At this time, it is possible to perform uniaxial stretching by appropriately adjusting the temperature of the winding roll and adding stretching in the extrusion direction. Further, simultaneous biaxial stretching, sequential biaxial stretching, and the like can be performed by stretching the film in a direction perpendicular to the extrusion direction.

  The thermoplastic resin film containing a (meth) acrylic resin or a lactone ring-containing polymer as a main component may be either an unstretched film or a stretched film. In the case of a stretched film, either a uniaxially stretched film or a biaxially stretched film may be used. In the case of a biaxially stretched film, either a simultaneous biaxially stretched film or a sequential biaxially stretched film may be used. In the case of biaxial stretching, the mechanical strength is improved and the film performance is improved. The thermoplastic resin film containing a (meth) acrylic resin or a lactone ring-containing polymer as a main component can suppress an increase in retardation even when stretched by mixing other thermoplastic resins. Optical isotropy can be maintained.

  The stretching temperature is preferably in the vicinity of the glass transition temperature of the thermoplastic resin composition that is the film raw material, and specifically, preferably (glass transition temperature-30 ° C) to (glass transition temperature + 100 ° C), more preferably. Is within the range of (glass transition temperature−20 ° C.) to (glass transition temperature + 80 ° C.). If the stretching temperature is less than (glass transition temperature-30 ° C.), a sufficient stretching ratio may not be obtained. Conversely, when the stretching temperature exceeds (glass transition temperature + 100 ° C.), the resin composition may flow, and stable stretching may not be performed.

  The draw ratio defined by the area ratio is preferably in the range of 1.1 to 25 times, more preferably 1.3 to 10 times. If the draw ratio is less than 1.1 times, the toughness accompanying the drawing may not be improved. On the other hand, when the draw ratio exceeds 25 times, the effect of increasing the draw ratio may not be recognized.

  The stretching speed is unidirectional, preferably 10 to 20000% / min, more preferably 100 to 10000% / min. When the stretching speed is less than 10% / min, it takes time to obtain a sufficient stretching ratio, and the production cost may increase. Conversely, when the stretching speed exceeds 20000% / min, the stretched film may break.

  In addition, a film containing a (meth) acrylic resin or a lactone ring-containing polymer as a main component is subjected to a heat treatment (annealing) after the stretching treatment in order to stabilize its optical isotropy and mechanical properties. be able to. The conditions for the heat treatment may be appropriately selected similarly to the conditions for the heat treatment performed on a conventionally known stretched film, and are not particularly limited.

  The thickness of the thermoplastic resin film mainly composed of (meth) acrylic resin or lactone ring-containing polymer is preferably 5 to 200 μm, more preferably 10 to 100 μm. When the thickness is less than 5 μm, not only the strength of the film is lowered, but also when the durability test of the polarizing plate is conducted, the crimp may be increased. On the other hand, when the thickness exceeds 200 μm, not only the transparency of the film is lowered, but also the moisture permeability becomes small, and when a water-based adhesive is used, the drying speed of the solvent water may be slow. .

  The thermoplastic resin film mainly composed of a (meth) acrylic resin or a lactone ring-containing polymer has a surface wetting tension of preferably 40 mN / m or more, more preferably 50 mN / m or more, and even more preferably 55 mN. / M or more. When the surface wetting tension is at least 40 mN / m or more, the adhesive strength between the thermoplastic resin film mainly containing a lactone ring-containing polymer and the polarizer is further improved. In order to adjust the surface wetting tension, for example, corona discharge treatment, ozone spraying, ultraviolet irradiation, flame treatment, chemical treatment, and other conventionally known surface treatments can be performed.

<Layer containing positive birefringent resin>
In this invention, it is preferable that the layer containing positive birefringent resin contains at least 1 sort (s) of polyetherketone, polyamide, polyester, a polyimide, a polyamideimide, and a polyesterimide. The polyether ketone is particularly preferably a polyaryl ether ketone.

  Specific examples of the above-described polyether ketone, particularly polyaryl ether ketone, include those having a repeating unit represented by the following general formula (4) (Japanese Patent Laid-Open No. 2001-49110).

In the general formula (4), X is a halogen, an alkyl group, or an alkoxy group, and the number of X bonds to the benzene ring q, that is, the p-tetrafluorobenzoylene group and the oxyalkylene group are not bonded. The value of the number of substitutions q of hydrogen atoms is an integer of 0-4. R ¹ is a compound (group) represented by the following general formula (2), and m is 0 or 1. Further, n represents the degree of polymerization, preferably 2 to 5000, particularly preferably 5 to 500.

  In addition, as a halogen as X in the said General formula (4), a fluorine atom, a bromine atom, a chlorine atom, an iodine atom etc. are mentioned, for example, A fluorine atom is preferable. Examples of the alkyl group include linear or branched alkyl groups having 1 to 6 carbon atoms such as a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group. A halogenated alkyl group such as a group, an ethyl group or a trifluoromethyl group thereof is preferred.

  Furthermore, examples of the alkoxy group include linear or branched alkoxy groups having 1 to 6, especially 1 to 4, such as methoxy group, ethoxy group, propoxy group, isopropoxy group, and butoxy group. A halogenated alkoxy group such as a methoxy group, an ethoxy group, or a trifluoromethoxy group thereof is preferable. In the above, X is particularly preferably a fluorine atom.

  On the other hand, in the group represented by the general formula (5), X ′ is a halogen, an alkyl group, or an alkoxy group, and the value of the number of bonds q ′ of X ′ to the benzene ring is an integer of 0 to 4. . Examples of the halogen, alkyl group or alkoxy group as X ′ are the same as those described above for X.

  Preferred X ′ is a fluorine atom, a methyl group or an ethyl group, a halogenated alkyl group such as a trifluoromethyl group thereof, a methoxy group or an ethoxy group, or a halogenated alkoxy group such as a trifluoromethoxy group thereof. Atoms are preferred.

  In the general formula (4), X and X ′ may be the same or different. Further, in the general formulas (4) and (5), two or more X or X ′ present in the molecule based on q or q ′ being 2 or more may be the same or different from each other. It may be.

Particularly preferred R ¹ is a group represented by the following general formula (6).

In the general formulas (5) and (6), R ² is a divalent aromatic group, and P is 0 or 1. Examples of the divalent aromatic group include (o, m or p-) phenylene group, naphthalene group, biphenyl group, anthracene group, (o, m or p-) terphenyl group, phenanthrene group, dibenzofuran group, biphenyl. Examples thereof include an ether group, a biphenyl sulfone group, and a divalent aromatic group represented by the following formula. In the divalent aromatic group, hydrogen directly bonded to the aromatic ring may be substituted with the halogen, alkyl group or alkoxy group described above.

In the above, preferable divalent aromatic groups (R ² ) are those represented by the following formulae.

  The polyaryl ether ketone represented by the general formula (4) may be composed of the same repeating unit, or may have two or more different repeating units. In the latter case, each repeating unit may exist in a block form or may exist randomly.

  Based on the above, the preferable polyaryl ether ketone represented by the general formula (4) is represented by the following general formula (7).

  A preferable polyaryletherketone including a group at the molecular end is represented by the following general formula (8) corresponding to the general formula (4), and corresponds to the general formula (7). Is represented by the following general formula (9). In these, a fluorine atom is bonded to the p-tetrafluorobenzoylene group side in the molecule, and a hydrogen atom is bonded to the oxyalkylene group side.

  On the other hand, specific examples of the polyamide or polyester described above include those having a repeating unit represented by the following general formula (10).

  In the general formula (10), B is halogen, an alkyl group having 1 to 3 carbon atoms or a halide thereof, a phenyl group substituted with one or more of them, or an unsubstituted phenyl group. . z is an integer of 0-3.

E is a covalent bond, an alkenyl group having 2 carbon atoms or a halide thereof, CH ₂ group, C (CX ₃ ) ₂ group, CO group, O atom, S atom, SO ₂ group, Si (R) ₂ group, or NR group. X in the C (CX ₃ ) ₂ group is a hydrogen atom or halogen, and R in the Si (R) ₂ group and the NR group is an alkyl group having 1 to 3 carbon atoms or a halide thereof. E is in a meta position or a para position with respect to the carbonyl group or the Y group. Halogen is a fluorine atom, a chlorine atom, an iodine atom or a bromine atom (hereinafter the same in general formula (7)).

  Y is an O atom or an NH group. A is a hydrogen atom, halogen, an alkyl group having 1 to 3 carbon atoms or a halide thereof, a nitro group, a cyano group, a thioalkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms or a halide thereof, aryl Group or a halide thereof, an alkyl ester group having 1 to 9 carbon atoms, an aryl ester group having 1 to 12 carbon atoms or a substituted derivative thereof, or an arylamide group having 1 to 12 carbon atoms or a substituted derivative thereof.

  N is an integer of 0 to 4, p is an integer of 0 to 3, q is an integer of 1 to 3, and r is an integer of 0 to 3. A preferred polyamide or polyester has a repeating unit represented by the following general formula (11) in which r and q are 1, and at least one of the biphenyl rings is substituted at the 2-position and the 2′-position. Is.

  In the general formula (11), m is an integer of 0 to 3, preferably 1 or 2, and x and y are 0 or 1, and both are not 0. The other symbols have the same meanings as those in the general formula (10), but E is a covalent bond having a para orientation with respect to the carbonyl group or the Y group.

  In the general formulas (10) and (11), when a plurality of B, E, Y, or A are present in the molecule, they may be the same or different. Similarly, z, n, m, x, and y may be the same or different. In this case, B, E, Y, A, z, n, m, x, and y are determined independently.

  The polyamide or polyester represented by the general formula (10) may be composed of the same repeating unit, or may have two or more different repeating units. In the latter case, each repeating unit may exist in a block form or may exist randomly.

  On the other hand, specific examples of the polyimide described above include, for example, a condensation polymerization product of 9,9-bis (aminoaryl) fluorene and an aromatic tetracarboxylic dianhydride, and are represented by the following general formula (12). And those having one or more repeating units.

  In the general formula (12), R is a hydrogen atom, a halogen, a phenyl group, a phenyl group substituted with 1 to 4 halogens or an alkyl group having 1 to 10 carbon atoms, or 1 to 10 An alkyl group having a carbon atom. Four Rs can be determined independently and can be substituted in the range of 0 to 4. The substituents are preferably those described above, but some of them may be different. Halogen is a fluorine atom, a chlorine atom, an iodine atom or a bromine atom (hereinafter the same in general formula (12)).

  Z is a trisubstituted aromatic group having 6 to 20 carbon atoms. Preferred Z is a pyromellitic group, a polycyclic aromatic group such as a naphthylene group, a fluorenylene group, a benzofluorenylene group or an anthracenylene group or a substituted derivative thereof, or a group represented by the following general formula (13). is there. Examples of the substituent in the substituted derivative of the polycyclic aromatic group include halogen, an alkyl group having 1 to 10 carbon atoms, or a fluorinated product thereof.

In the general formula (13), D is a covalent bond, C (R ² ) ₂ group, CO group, O atom, S atom, SO ₂ group, Si (C ₂ H ₅ ) ₂ group, N (R ³ ₂ ) or a combination thereof, m is an integer of 1-10. R ² is independently a hydrogen atom or a C (R ⁴ ) ₃ group. R ³ is independently a hydrogen atom, an alkyl group having 1 to about 20 carbon atoms, or an aryl group having about 6 to about 20 carbon atoms. Each R ⁴ is independently a hydrogen atom, a fluorine atom or a chlorine atom.

  Moreover, what has a unit represented by following General formula (14), (15) as a polyimide other than the above can be mentioned. Moreover, the polyimide which has a unit represented by General formula (16) is preferable.

  In the general formulas (14), (15), and (16), T and L are halogen, an alkyl group having 1 to 3 carbon atoms or a halide thereof, phenyl substituted with one or more of them. Group or an unsubstituted phenyl group. The halogen is a fluorine atom, a chlorine atom, an iodine atom or a bromine atom (hereinafter the same in the general formulas (14), (15) and (16)). z is an integer of 0-3.

G and J are covalent bonds or bond bonds, CH ₂ groups, C (CX ₃ ) ₂ groups, CO groups, O atoms, S atoms, SO ₂ groups, Si (C ₂ H ₅ ) ₂ groups, or N ( CH ₃ ) group. X in the C (CX ₃ ) ₂ group is a hydrogen atom or halogen (hereinafter the same in general formulas (14), (15), and (16)).

  A is a hydrogen atom, a halogen, an alkyl group or a halide thereof, a nitro group, a cyano group, a thioalkyl group, an alkoxy group or a halide thereof, an aryl group or a halide thereof, or an alkyl ester group or a substituted derivative thereof.

  R is a hydrogen atom, a substituted phenyl group such as a halogen, a phenyl group or a halide thereof, or a substituted alkyl group such as an alkyl group or a halide thereof. n is an integer of 0 to 4, p is an integer of 0 to 3, and q is an integer of 1 to 3.

  In the above general formulas (14), (15), and (16), when a plurality of T, A, R, or L are present in the molecule, they may be the same or different. May be. Similarly, z, n, and m may be the same or different. In this case, T, A, R, L, z, n, and m are determined independently.

  The polyimides represented by the general formulas (12), (14), (15), and (16) may be composed of the same repeating unit or have two or more different repeating units. It may be. The different repeating unit may be formed by copolymerizing one or more of acid dianhydrides and / or diamines other than those described above. As the diamine, an aromatic diamine is particularly preferable. When it has the latter different repeating unit, each repeating unit may exist in a block shape or may exist randomly.

  Examples of the acid dianhydride for forming the different repeating units include pyromelt acid dianhydride, 3,6-diphenylpyromelt acid dianhydride, and 3,6-bis (trifluoromethyl) pyromelt acid dianhydride. 3,6-dibromopyromelt acid dianhydride, 3,6-dichloropyromelt acid dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 2,3,3 ′ , 4′-benzophenone tetracarboxylic dianhydride, 2,2 ′, 3,3′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenylcarboxylic dianhydride, bis (2 , 3-dicarbophenyl) methane dianhydride.

  Also, bis (2,5,6-trifluoro-3,4-dicarboxyphenyl) methane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3- Hexafluoropropane dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride (4,4′-oxydiphthalic anhydride), bis (3,4-dicarboxyphenyl) sulfone dianhydride (3,3 3 ', 4,4'-diphenylsulfonetetracarboxylic anhydride), 4,4'-[4,4'-isopropylidene-di (p-phenyleneoxy)] bis (phthalic anhydride) is An example of an anhydride is given.

  Furthermore, N, N- (3,4-dicarboxyphenyl) -N-methylamine dianhydride, bis (3,4-dicarboxyphenyl) diethylsilane dianhydride, 2,3,6,7-naphthalene-tetra Naphthalenetetracarboxylic acids such as carboxylic dianhydrides, 1,2,5,6-naphthalene-tetracarboxylic dianhydrides, 2,6-dichloro-naphthalene-1,4,5,8-tetracarboxylic dianhydrides Acid dianhydride, thiophene-2,3,4,5-tetracarboxylic dianhydride and pyrazine-2,3,5,6-tetracarboxylic dianhydride, pyridine-2,3,5,6-tetra Heterocyclic aromatic tetracarboxylic dianhydrides such as carboxylic dianhydrides are also examples of the acid dianhydrides.

  Preferably used acid dianhydrides are 2,2′-dibromo-4,4 ′, 5,5′-biphenyltetracarboxylic dianhydride and 2,2′-dichloro-4,4 ′, 5,5 ′. -Biphenyltetracarboxylic dianhydrides, 2,2'-substituted dianhydrides such as 2,2'-trihalo-substituted dianhydrides, especially 2,2-bis (trifluoromethyl) -4,4 ' , 5,5'-biphenyltetracarboxylic dianhydride is preferred.

  On the other hand, examples of the diamine for forming the different repeating units include (o, m or p-) phenylenediamine, 2,4-diaminotoluene, 1,4-diamino-2-methoxybenzene, 1,4- Benzenediamine such as diamino-2-phenylbenzene, 1,3-diamino-4-chlorobenzene, 4,4′-diaminobiphenyl, 4,4-diaminodiphenylmethane, 2,2-bis (4-aminophenyl) propane, 2 , 2-bis (4-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 1,3-bis ( 3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) ), And benzene.

  4,4′-bis (4-aminophenoxy) biphenyl, 4,4′-bis (3-aminophenoxy) biphenyl, 2,2-bis (4- (4-aminophenoxy) phenyl) propane, 2,2 -Bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 4,4′-diaminodiphenylthioether, 4,4′-diaminodiphenylsulfone, 2, 2'-diaminobenzophenone, 3,3'-diaminobenzophenone, naphthalenediamine such as 1,8-diaminonaphthalene and 1,5-diaminonaphthalene, 2,6-diaminopyridine, 2,4-diaminopyridine, 2,4- Heteroaromatic diamines such as diamino-S-triazine are also examples of the diamines described above.

  Examples of polyimides that can be preferably used include 2,2′-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride and 4,4′-bis (3,4-dicarboxyphenyl) -2,2-diphenyl. Heat-resistant and solvent-soluble polyimides prepared using aromatic dianhydrides such as propane dianhydride, naphthalenetetracarboxylic dianhydride and bis (3,4-dicarboxyphenyl) sulfone dianhydride It is.

  Examples of diamines include 4,4- (9-fluorenylidene) -dianiline, 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl, and 3,3′-dichloro-4,4′-diamino. Diphenylmethane, 2,2′-dichloro-4,4′-diaminobiphenyl, 2,2 ′, 5,5′-tetrachlorobenzidine, 2,2-bis (4-aminophenoxyphenyl) propane, 2,2-bis (4-aminophenoxyphenyl) hexafluoropropane, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, etc. A heat-resistant and solvent-soluble polyimide prepared using an aromatic diamine can be preferably used.

  On the other hand, the above-mentioned polyamideimide or polyesterimide is not particularly limited, and one or more suitable types can be used. Of these, polyamide imides described in JP-A No. 61-162512 and polyester imides described in JP-A No. 64-38472 can be preferably used.

  The molecular weight of the solid polymer for forming the polymer layer is not particularly limited, but is preferably soluble in a solvent. Weight average molecular weight in terms of coating film thickness accuracy, surface accuracy or surface smoothness, film strength, prevention of cracking due to expansion and contraction and distortion when formed into a film, and solubility in solvents (preventing gelation) 10,000 to 1,000,000, preferably 20,000 to 500,000, particularly 50,000 to 200,000. The weight average molecular weight is a value measured by gel permeation chromatography (GPC) using polyethylene oxide as a standard sample and a dimethylformamide solvent.

  For the formation of the polymer layer, the above-mentioned polyaryletherketone, polyamide, polyester, polyimide, or other solid polymer may be used alone, or two or more of the same species may be mixed and used. Further, for example, a mixture of two or more polymers having different functional groups, such as a mixture of polyaryl ether ketone and polyamide, may be used.

  Moreover, you may use together 1 type (s) or 2 or more types of suitable polymers other than the above in the range which the orientation of the said solid polymer which forms a polymer layer does not fall remarkably. Incidentally, examples of the combined polymer include polyethylene, polypropylene, polystyrene, polymethyl methacrylate, ABS resin and AS resin, polyacetate, polycarbonate, polyamide, polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, polyethersulfone, polyketone, polyimide, Examples thereof include thermoplastic resins such as polycyclohexanedimethanol terephthalate, polyarylate, and liquid crystal polymer (including a photopolymerizable liquid crystal monomer).

  Thermosetting resins such as epoxy resins, phenol resins, and novolac resins are also examples of the combined polymer. The amount of the combined polymer used is not particularly limited as long as the orientation is not significantly lowered, but is usually 50% by mass or less, preferably 40% by mass or less, and particularly preferably 30% by mass or less.

  For liquefaction of the solid polymer forming the polymer layer, an appropriate method such as a method of heating and melting if the solid polymer is a thermoplastic polymer or a method of dissolving the solid polymer in a solvent to form a solution is adopted. Can do. Therefore, the solidification of the polymer layer can be performed by cooling the polymer layer in the former melt and by drying after removing the solvent from the polymer layer in the latter solution. In forming the polymer layer, various additives including stabilizers, plasticizers, metals, and the like can be blended as necessary.

  Drying after the coating of the polymer layer can be performed by a natural drying (air drying) method or a heat drying method, generally hot air, infrared rays, a heating roll, microwaves, or the like. It is preferable to carry out with hot air in terms of simplicity. It is preferable that the drying temperature is gradually increased in the range of 40 to 180 ° C. in the range of 3 to 5 stages by the zone drying method in consideration of the stretching process temperature by a tenter or the like that is the next step. It is more preferable to carry out in the range of 170 ° C. in order to improve physical properties such as scratch resistance and dimensional stability of the polymer layer.

  Examples of the solvent include chloroform, dichloromethane, carbon tetrachloride and dichloroethane, tetrachloroethane and trichloroethylene, halogenated hydrocarbons such as tetrachloroethylene, chlorobenzene and orthodichlorobenzene, phenols such as phenol and parachlorophenol, benzene and toluene, Aromatic hydrocarbons such as xylene, methoxybenzene, 1,2-dimethoxybenzene, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, 2-pyrrolidone, ketones such as N-methyl-2-pyrrolidone, acetic acid Examples include esters such as ethyl and butyl acetate.

  Further, alcohols such as t-butyl alcohol and glycerin, ethylene glycol and triethylene glycol, ethylene glycol monomethyl ether and diethylene glycol dimethyl ether, propylene glycol and dipropylene glycol and 2-methyl-2,4-pentanediol, dimethylformamide and dimethyl Examples of the solvent include amides such as acetamide, nitriles such as acetonitrile and butyronitrile, ethers such as diethyl ether, dibutyl ether and tetrahydrofuran, methylene chloride, carbon disulfide, ethyl cellosolve and butyl cellosolve.

  A solvent can be used individually or in mixture of 2 or more types in an appropriate combination. From the viewpoint of coating viscosity and the like, the solution is preferably prepared by dissolving 2 to 100 parts by mass, preferably 5 to 50 parts by mass, particularly 10 to 40 parts by mass of the solid polymer with respect to 100 parts by mass of the solvent.

  For development on thermoplastic resin film, for example, spin coating method, roll coating method, flow coating method, printing method, dip coating method, casting method such as bar coating method and gravure printing method, extrusion method, ink jet method, etc. An appropriate coating layer forming method can be adopted. Among these, the extrusion method is preferable from the viewpoint of mass productivity of a film having little thickness unevenness and alignment strain unevenness.

  For the polymer layer, the polymer solution dissolved in a solvent and liquefied as described above is applied onto the thermoplastic resin film and dried, and the support is subjected to a stretching treatment described later. The stretching treatment is preferably performed by a tenter method. According to this method, the polymer layer can be processed in a state of being supported by the base material, and the manufacturing efficiency and processing accuracy are excellent, and continuous manufacturing is also possible.

(Stretching operation)
A preferred stretching operation for the retardation film of the present invention will be described.

  The retardation film of the present invention includes a layer containing a (meth) acrylic resin, preferably a layer containing a (meth) acrylic resin having a lactone ring structure (thermoplastic resin film), and a positive birefringent resin. After laminating at least one layer (polymer layer) with each other, it is preferable to control the retardation by stretching by the following stretching operation. Further, before the polymer layer is provided, the thermoplastic resin film alone may be stretched to control the phase difference.

  Stretching is preferably performed in one direction of the retardation film by 1.0 to 2.0 times, and the other is stretched by about 0.7 to 1.5 times.

  For example, the film can be stretched sequentially or simultaneously in the longitudinal direction of the film and in the direction perpendicular to the film plane, that is, in the width direction, but at this time, it is sufficient if the stretching ratio in at least one direction is too small. If the phase difference cannot be obtained and is too large, stretching may be difficult and fracture may occur.

  As the retardation film, in order to control the retardation in the in-plane direction or the thickness direction, free end uniaxial stretching in the film forming direction, or unbalanced biaxial stretching that stretches in the width direction and contracts in the casting direction may be performed. .

  The retardation film coated with the polymer layer is 50 to 180 ° C. or less, more preferably 60 to 160 ° C. or less, still more preferably 70 to 150 ° C. or less, 5 seconds or more and 3 minutes or less, more preferably 10 prior to stretching. It is preferable to perform heat treatment (pre-heat treatment) for not less than 2 seconds and not more than 2 minutes, more preferably not less than 15 seconds and not more than 90 seconds. This heat treatment is preferably performed from immediately before gripping the film with a tenter to immediately before stretching starts. Particularly preferably, it is carried out between the time when the film is held by a tenter and the time immediately before stretching starts.

  The stretching is preferably performed at 5 to 300% / min, more preferably 10 to 200% / min, and further preferably 15 to 150% / min. The stretching is preferably performed by gripping both ends of the film using a tenter.

  The stretching angle is preferably 2 ° to 10 °, more preferably 3 ° to 7 °, and most preferably 3 ° to 5 °. The stretching speed may be constant or may be changed.

  40-250 degreeC is preferable and the temperature at the time of extending | stretching has more preferable 70-180 degreeC.

The atmospheric temperature in the tenter process is preferably less distributed, preferably within ± 5 ° C in the width direction, more preferably within ± 2 ° C, even more preferably within ± 1 ° C, and most preferably within ± 0.5 ° C. . In the tenter process, preferably subjected to heat treatment in the heat transfer coefficient ^{20J / m 2 hr~130 × 10 3} J / m 2 hr. More preferably, in the range of ^{40J / m 2 hr~130 × 10 3} J / m 2 hr, and most preferably in the range of ^{42J / m 2 hr~84 × 10 3} J / m 2 hr.

  The film transport tension in the film forming process such as in the tenter depends on the temperature, but is preferably 120 N / m to 200 N / m, and more preferably 140 N / m to 200 N / m. 140 N / m to 160 N / m is most preferable.

  In order to prevent unintended film elongation in the film forming process, it is preferable to provide a tension cut roll in front of or behind the tenter.

The retardation film according to the present invention is preferably subjected to a heat treatment after stretching to relieve the remaining strain. The heat treatment is preferably performed at 110 to 150 ° C, preferably 100 to 180 ° C, more preferably 130 to 160 ° C. In this case, it is preferable to carry out the heat treatment in the heat transfer coefficient ^{20J / m 2 hr~130 × 10 3} J / m 2 hr. More preferably, in the range of ^{40J / m 2 hr~130 × 10 3} J / m 2 hr, and most preferably in the range of ^{42J / m 2 hr~84 × 10 3} J / m 2 hr. As a result, the remaining strain is reduced, and the dimensional stability under high-temperature conditions such as 90 ° C. or high-temperature high-humidity conditions such as 80 ° C. and 90% RH is improved.

  The stretched film is cooled to room temperature after stretching. The stretched film preferably starts to be cooled while being held in a width by a tenter, and the width held by the tenter during this period is 1 to 10%, more preferably 2 to 9%, relative to the film width after stretching. More preferably, it is reduced and relaxed by 2% or more and 8% or less. The cooling rate is preferably 10 to 300 ° C./min, more preferably 30 to 250 ° C./min, and still more preferably 50 to 200 ° C./min. Although it may be cooled to room temperature while being gripped by the tenter, it is preferable to stop gripping halfway and switch to roll conveyance, and then it is wound into a roll.

  The retardation film of the present invention produced as described above has the following characteristics.

(optical properties)
The retardation film of the present invention comprises at least one layer containing a (meth) acrylic resin, particularly a layer containing a (meth) acrylic resin having a lactone ring structure, and a layer containing a positive birefringent resin. In a laminated state, the retardation value Ro defined by the following formula is preferably 20 to 300 nm and the retardation value Rt is preferably in the range of −600 to 600 nm. Further, a more preferable range is a range where the Ro value is 20 to 120 nm and an Rt value is -400 to 400 nm, and a particularly preferable range is a range where the Ro value is 40 to 100 nm and the Rt value is -300 to 300 nm.

Formula (a) Ro = (nx−ny) × d
Formula (b) Rt = ((nx + ny) / 2−nz) × d
(In the formula, Ro is the retardation value in the film plane, Rt is the retardation value in the film thickness direction, nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, (nz represents the refractive index in the thickness direction of the film (the refractive index is measured at a wavelength of 590 nm), and d represents the thickness (nm) of the film.)
Retardation was measured at 10 locations at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH using an automatic birefringence meter (manufactured by Oji Scientific Instruments, KOBRA-21ADH). The retardation Ro in the in-plane direction represented, and the retardation Rt in the thickness direction represented by the formula (b) are obtained. Measure 10 places each and show the average value. The average refractive index can be obtained by an Abbe refractometer.

  The retardation film of the present invention is particularly advantageously used as a retardation film of a VA liquid crystal display device having a VA mode liquid crystal cell. The retardation film used in the VA liquid crystal display device preferably has a Ro value of 20 to 150 nm and an Rt value of 70 to 400 nm. The Ro value is more preferably 30 to 100 nm. When two retardation films are used in the VA liquid crystal display device, the Rt value of the film is preferably 70 to 250 nm. When one retardation film is used for the VA liquid crystal display device, the Rt value of the film is preferably 150 to 400 nm.

  By setting the retardation value within the above range, the optical performance as a retardation film for a polarizing plate can be sufficiently satisfied.

(Polarizer)
The polarizing plate of the present invention and the liquid crystal display device of the present invention using the polarizing plate will be described.

  The polarizing plate of the present invention can be produced by a general method. The back side of the retardation film of the present invention is subjected to alkali saponification treatment, and the treated film can be bonded to both sides of a polarizer prepared by immersing and stretching in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution. preferable.

  A polarizer, which is a main component of a polarizing plate, is an element that allows only light of a plane of polarization in a certain direction to pass. A typical polarizer currently known is a polyvinyl alcohol-based polarizing film, which is polyvinyl alcohol. There are one in which iodine is dyed on a system film and one in which dichroic dye is dyed. For the polarizer, a polyvinyl alcohol aqueous solution is formed into a film and dyed by uniaxial stretching or dyed or uniaxially stretched and then preferably subjected to a durability treatment with a boron compound. The film thickness of the polarizer is 5 to 40 μm, preferably 5 to 30 μm, and particularly preferably 5 to 25 μm. A polarizing plate is formed by laminating the retardation film of the present invention on the surface of the polarizer.

  The retardation film can be bonded with a water-based adhesive mainly composed of completely saponified polyvinyl alcohol or the like, or can be bonded to a polarizing plate through an appropriate adhesive layer.

  Since the polarizer is stretched in a uniaxial direction (usually the longitudinal direction), when the polarizing plate is placed in a high-temperature and high-humidity environment, the stretching direction (usually the longitudinal direction) shrinks, and the direction perpendicular to the stretching (usually the width direction) ) Will grow. As the thickness of the polarizing plate protective film decreases, the expansion / contraction ratio of the polarizing plate increases, and in particular, the amount of contraction in the stretching direction of the polarizer increases. Normally, the direction of stretching of the polarizer is bonded to the casting direction (MD direction) of the polarizing plate protective film. Therefore, when thinning the polarizing plate protective film, it is particularly important to suppress the stretch rate in the casting direction. It is. Since the retardation film used in the present invention is excellent in dimensional stability, it is suitably used as such a polarizing plate protective film.

  The retardation film of the present invention may be used on the other surface of the polarizing plate, or another polarizing plate protective film may be used. For the retardation film of the present invention, there is no particular limitation on the polarizing plate protective film used on the other side, but for example, triacetyl cellulose film, cellulose acetate propionate onate film, cellulose diacetate film, cellulose acetate butyrate Cellulose ester film such as rate film, polyester film such as polyethylene terephthalate and polyethylene naphthalate, polycarbonate film, polyarylate film, polysulfone (including polyethersulfone) film, polyethylene film, polypropylene film, cellophane, poly Vinylidene chloride film, polyvinyl alcohol film, ethylene vinyl alcohol film, syndiotactic polystyrene film , Norbornene resin film, polymethylpentene film, polyether ketone film, polyether ketone imide film, polyamide film, fluororesin film, nylon film, cycloolefin polymer film, polymethyl methacrylate film, acrylic film, etc. However, it is not limited to these. Among these, cellulose ester films (for example, Konica Minoltak KC8UX2M, KC4UX2M, KC4UY, KC8UT, KC5UN, KC12UR, KC8UCR-3, KC8UCR-4 (above, manufactured by Konica Minolta Opto), polycarbonate film, cycloolefin A polymer film and a polyester film are preferable, and in the present invention, a cellulose ester film is particularly preferable in terms of production, cost, isotropy, adhesiveness, and object effects of the present invention.

(Liquid crystal display device)
By incorporating the polarizing plate of the present invention into a display device, the liquid crystal display device of the present invention having various visibility can be manufactured. In particular, it is preferably applied to a VA type (MVA type, PVA type) liquid crystal display device.

  The liquid crystal display device using the polarizing plate of the present invention is particularly effective for use in a multi-domain liquid crystal display device, more preferably a multi-domain liquid crystal display device with a birefringence mode. Can do.

  Multi-domain is a method of dividing a liquid crystal cell that constitutes one pixel into a plurality of parts, which is suitable for improving the viewing angle dependency and improving the symmetry of image display, and various methods have been reported. “Okita, Yamauchi: Liquid Crystal, 6 (3), 303 (2002)”. The liquid crystal display cell is also shown in “Yamada, Yamabara: Liquid Crystal, 7 (2), 184 (2003)”, but is not limited thereto.

  The display quality of the display cell is preferably symmetrical with respect to human observation. Therefore, when the display cell is a liquid crystal display cell, it is possible to multiplex domains by giving priority to the symmetry on the observation side. A known method can be used to divide the domain, and it can be determined by a two-division method, more preferably a four-division method in consideration of the properties of a known liquid crystal mode.

  The polarizing plate of the present invention is effective in the MVA (Multi-domain Vertical Alignment) mode represented by the vertical alignment mode, in particular, the MVA mode divided into four, and the known PVA (Patterned Vertical Alignment) mode multi-domained by electrode arrangement. Can be used.

  In particular, a polarizing plate using the retardation film of the present invention exhibits excellent durability when used in a large-screen liquid crystal display device. In a large-screen liquid crystal display device with a 17-inch or larger screen, especially a 30-inch or larger screen, there is no distortion such as color unevenness and wavy unevenness in addition to the effects of the present invention, so eyes are not tired even during long-time viewing. There was an effect.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

(Measurement of retardation)
Retardation was measured at 10 locations at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH using an automatic birefringence meter (manufactured by Oji Scientific Instruments, KOBRA-21ADH). The retardation Ro in the in-plane direction represented, and the retardation Rt in the thickness direction represented by the formula (b) were determined. Measure 10 places each and show the average value. The average refractive index was determined with an Abbe refractometer.

Formula (a) Ro = (nx−ny) × d
Formula (b) Rt = ((nx + ny) / 2−nz) × d
(In the formula, Ro is the retardation value in the film plane, Rt is the retardation value in the film thickness direction, nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, (nz represents the refractive index in the thickness direction of the film (the refractive index is measured at a wavelength of 590 nm), and d represents the thickness (nm) of the film.)
Example 1
<Preparation of base film A1>
A 30 L reaction kettle equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introduction pipe was charged with 8000 g of methyl methacrylate (MMA), 2000 g of methyl 2- (hydroxymethyl) methyl acrylate (MHMA), and 10,000 g of toluene. When the temperature was raised to 105 ° C. while refluxing nitrogen and refluxed, 10.0 g of tertiary amyl peroxyisononanoate (manufactured by Atofina Yoshitomi, trade name: Lupazole 570) was added as an initiator, and at the same time 20.0 g While a solution consisting of the above initiator and 100 g of toluene was added dropwise over 4 hours, solution polymerization was performed under reflux (about 105 to 110 ° C.), followed by further aging over 4 hours.

  To the obtained polymer solution, 10 g of stearyl phosphate / distearyl phosphate mixture (manufactured by Sakai Chemicals, trade name: Phoslex A-18) was added and cyclized under reflux (about 90 to 110 ° C.) for 5 hours. A condensation reaction was performed. Subsequently, the polymer solution obtained by the cyclization condensation reaction was subjected to a vent having a barrel temperature of 260 ° C., a rotation speed of 100 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent number of 1, and a forevent number of 4 It is introduced into a type screw twin screw extruder (Φ = 29.75 mm, L / D = 30) at a processing rate of 2.0 kg / hour in terms of resin amount, and cyclization condensation reaction and devolatilization are carried out in the extruder. By extrusion, transparent lactone ring-containing acrylic resin pellets were obtained.

  The lactone ring-containing acrylic resin pellet had a lactone cyclization rate of 97.0%, a mass average molecular weight of 147700, a melt flow rate of 11.0 g / 10 min, and a Tg (glass transition temperature) of 130 ° C.

  The obtained pellets were supplied to an extruder, melted and kneaded at 250 ° C., extruded from a T-die, cooled with water using a cooling roll, and taken to obtain a lactone ring-containing acrylic resin film A1 having a thickness of 55 μm.

<Preparation of retardation film 1>
Weight average molecular weight of 59,000 synthesized from 2,2′-bis (3,4-dicarboxyphenyl) hexafluoropropane and 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl 15% by weight cyclohexanone solution of polyimide B1 is coated on the base film A1 to form a polyimide layer, dried, and then dried at 150 ° C. with a tenter in the TD direction (direction perpendicular to the film transport direction, width direction) The film was stretched 1.2 times to obtain a retardation film 1. The phase difference was Ro 50 nm and Rt 120 nm.

<Preparation of retardation films 2 to 5>
Retardation films 2 to 5 were obtained in the same manner as the retardation film 1 except that the stretching temperature was changed according to Table 1. The phase difference was Ro 50 nm and Rt 120 nm.

<Preparation of base film A2>
In a 30 L capacity reactor equipped with a stirrer, temperature sensor, cooling pipe, and nitrogen introduction pipe, 8,000 g of methyl methacrylate (MMA) and 2,000 g of methyl 2- (hydroxymethyl) methyl acrylate (MHMA) were added. ) 10,000 g of 4-methyl-2-pentanone (methyl isobutyl ketone, MIBK), 5 g of n-dodecyl mercaptan were charged, and the temperature was raised to 105 ° C. while passing nitrogen, and when the mixture was refluxed, the polymerization initiator At the same time as adding 5.0 g of t-butylperoxyisopropyl carbonate (Kaya-Carbon BIC-7, manufactured by Kayaku Akzo Co., Ltd.) and simultaneously adding a solution of 10.0 g of t-butylperoxyisopropyl carbonate and 230 g of MIBK. While dripping over 4 hours, solution polymerization is carried out at about 105 to 120 ° C. under reflux. 4 hours over a period of aging was carried out. To the obtained polymer solution, 30 g of stearyl phosphate / distearyl phosphate mixture (Phoslex A-18, manufactured by Sakai Chemical Industry Co., Ltd.) was added and cyclized at about 90-120 ° C. for 5 hours under reflux. A condensation reaction was performed. Next, the obtained polymer solution was a vent type screw twin screw extruder having a barrel temperature of 260 ° C., a rotation speed of 100 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent number of 1, and a forevent number of 4. (Φ = 29.75 mm, L / D = 30) in terms of resin amount, introduced at a processing rate of 2.0 kg / h, and further subjected to cyclization condensation reaction and devolatilization in this extruder and extruded. As a result, a transparent pellet of the lactone ring-containing polymer was obtained.

  The obtained lactone ring-containing polymer was measured for dynamic TG, and a mass loss of 0.17% by mass was detected. The lactone ring-containing polymer had a weight average molecular weight of 133,000, a melt flow rate of 6.5 g / 10 min, and a glass transition temperature of 131 ° C.

  The obtained pellets and acrylonitrile-styrene (AS) resin (Toyo AS AS20, manufactured by Toyo Styrene Co., Ltd.) are kneaded and extruded at a mass ratio of 90/10 using a single screw extruder (screw 30 mmφ). Thus, a transparent pellet was obtained. The obtained pellet had a glass transition temperature of 127 ° C.

  The obtained pellets were supplied to an extruder, melted and kneaded at 250 ° C., then extruded from a T-die, and cooled by water with a cooling roll and taken up to obtain a lactone ring-containing acrylic resin film A2 having a thickness of 60 μm.

<Preparation of retardation film 6>
5. Weight average molecular weight synthesized from 4,4′-bis (3,4-dicarboxyphenyl) -2,2-diphenylpropane dianhydride and 2,2′-dichloro-4,4′-diaminobiphenyl. A 20% by mass solution obtained by dissolving 20,000 polyimide B2 in cyclopentanone was applied to the base film A2, and stretched 1.25 times in the TD direction at 130 ° C. by a tenter during the drying process, A retardation film 6 was obtained. The phase difference was Ro 60 nm and Rt 210 nm.

<Preparation of base film A3>
Acrylic resin BR88 (manufactured by Mitsubishi Rayon) 80 parts by weight Methylene chloride 250 parts by weight Ethanol 10 parts by weight The above materials are sequentially put into a sealed container, the container is heated to 70 ° C., and the acrylic resin is stirred. It completely dissolved to obtain an acrylic resin solution (dope). Then, stirring was stopped and the liquid temperature was lowered to 43 ° C. The dope was filtered using a filter paper (Azumi filter paper No. 244, manufactured by Azumi Filter Paper Co., Ltd.) to obtain a dope. Subsequently, using a belt casting apparatus, it was uniformly cast on a stainless steel band support (surface temperature 35 ° C.) with a width of 2 m. The solvent was evaporated until the residual solvent amount reached 100%, and then peeled off from the stainless steel band support. The peeled web was evaporated at 55 ° C., then clipped with a tenter and stretched 1.01 times (1%) at 110 ° C. in the TD direction. Thereafter, drying was completed while roll-feeding at 100 ° C., slitting to a width of 1500 mm, and knurling with a width of 15 mm and an average height of 12 μm were applied to both ends of the film to obtain a base film A3. The film average film thickness was 55 μm, the film thickness variation was within ± 1 μm in both the width direction and the longitudinal direction, and the winding length was 5000 m.

<Preparation of retardation film 7>
In the same manner as the retardation film 1, the polyimide B1 is applied on the base film A3 and dried to form a polyimide layer, and stretched 1.2 times in the TD direction at 110 ° C. with a tenter. Got. The phase difference was Ro 50 nm and Rt 120.

<Preparation of retardation film 8>
In the same manner as the retardation film 1 on a commercially available acrylic film (Acryprene manufactured by Mitsubishi Rayon Co., Ltd.), the polyimide B1 was applied and dried to form a polyimide layer, and a tenter was 1.2 in the TD direction at 100 ° C. Double-stretching was performed to obtain a retardation film 4. The phase difference was Ro 50 nm and Rt 120.

<Preparation of retardation film 9>
An attempt was made to produce a retardation film 9 in the same manner as the retardation film 8 except that the stretching temperature was 130 ° C. However, the base film was melted and the film became wrinkled and could not be evaluated.

<< Evaluation of retardation film >>
About each obtained sample, the retardation value and scattered light intensity in each wavelength were measured in the following ways. The results are shown in Table 1.

(Scattered light intensity)
Goniophotometer model: GP-1-3D, manufactured by Optec Corporation (light source: 12V50W halogen bulb, light receiving part: photomultiplier tube (Photomaru Hamamatsu Photonics R636-10)).

  The amount of light at the time of measurement was corrected with the amount of light at θ = 180 ° (photomal light receiving sensitivity: −185 V), and the measured value at this amount of light was taken as the scattered light intensity. The samples were measured by fixing the slow axis of the film horizontally and vertically on the sample stage.

Example 2
<Preparation of polarizing plate>
A 120 μm-thick polyvinyl alcohol film was uniaxially stretched (temperature: 110 ° C., stretch ratio: 5 times). This was immersed in an aqueous solution composed of 0.075 g of iodine, 5 g of potassium iodide and 100 g of water for 60 seconds, and then immersed in an aqueous solution of 68 ° C. composed of 6 g of potassium iodide, 7.5 g of boric acid and 100 g of water. This was washed with water and dried to obtain a polarizer.

  Polyisocyanate compound (Dainippon) in 100 parts of an aqueous emulsion of polyester ionomer type urethane resin (trade name “Hydran AP-20” manufactured by Dainippon Ink & Chemicals, Inc., solid content concentration 30%, viscosity 30 mPa · sec) Ink Chemical Industry Co., Ltd. product name "Hydran Assist C1") 3 parts of the adhesive film, MD direction (film transport direction, longitudinal direction) of retardation film 1 and the stretching direction of the polarizer Were bonded so that the substrate films were on the polarizer side.

  Polarizers 1 to 8 were prepared by subjecting the other polarizer to Konica Minolta Tack Film KC4UY (manufactured by Konica Minolta Opto Co., Ltd.) by alkali saponification treatment in the same manner.

  Similarly, the polarizing plate 10 was obtained by bonding the Konica Minolta-tack film KC4UY to both sides of the polarizer.

<Production of liquid crystal display device>
A liquid crystal panel for viewing angle measurement was produced as follows, and the characteristics as a liquid crystal display device were evaluated. The polarizing plates on both sides of the 40-inch display KLV-40J3000 made by SONY were peeled off in advance, and the prepared polarizing plates 1 to 5, 7, and 8 were bonded to both surfaces of the glass surface of the liquid crystal cell, respectively.

  At that time, the direction of bonding of the polarizing plate is such that the surface of the retardation film of the present invention is on the liquid crystal cell side, and the absorption axis is in the same direction as the previously bonded polarizing plate. Thus, liquid crystal display devices 1 to 5, 7, and 8 were produced.

  Moreover, the liquid crystal display device 6 was produced in the same manner except that the polarizing plate 6 was bonded to the viewing side and the polarizing plate 10 was bonded to the backlight side.

(Moist heat cycle test)
This liquid crystal display device was evaluated for front contrast when a wet heat cycle test of humidity 80%, temperature 60 ° C., 1 hour and temperature −20 ° C., 1 hour was repeated 200 times. The results are shown in Table 3.

(Evaluation of front contrast)
Measurement was performed using EZ-Contrast 160D manufactured by ELDIM in an environment of 23 ° C. and 55% RH. The luminance from the normal direction of the display screen of white display and black display was measured with a liquid crystal display device, and the ratio was defined as the front contrast.

  Front contrast = (brightness of white display measured from normal direction of display device) / (brightness of black display measured from normal direction of display device)

  From Table 3, the liquid crystal display devices 1 to 4 and 6 using the retardation films 1 to 4 and 6 of the present invention are changed to the liquid crystal display devices 5 to 7 and 8 using the comparative retardation films 5, 7 and 8. It is clear that this is an excellent retardation film with less reduction in front contrast in the wet heat cycle test.

Example 3
Polyetherketone (trade name: Polyaryletherketone A, manufactured by Nippon Shokubai Co., Ltd.) having a weight average molecular weight (Mw) of 110000 represented by the following formula was dissolved in toluene solvent, ethyl acetate, and 2-methylpentanone solvent solvent, respectively. A 10% by weight polyetherketone solution was prepared. Except that this polyetherketone solution was used instead of the polyimide B1 solution, a layer containing polyetherketone was formed on the base film A1 in the same manner as the retardation film 1, and stretched in the same manner. A retardation film 11 having a phase difference of Ro 60 nm, Rt 140 nm, and a scattered light intensity difference of 0.02 was obtained.

  A polarizing plate 11 and a liquid crystal display device 11 were produced in the same manner except that the phase difference film 11 was used instead of the phase difference film 1, and a wet heat cycle test (front contrast evaluation) was performed. And was found to be an excellent retardation film with little decrease in front contrast in the wet heat cycle test.

It is the schematic of a goniophotometer.

Explanation of symbols

G1 Light source lamp G2 Spectrometer G3 Sample stage (stage)
G5 Light receiving portion G6 Sample holding spring G7 Angle indexing rotary table θ Angle formed by the normal direction of the light source and the direction connecting the observation point of the sample and the integrating sphere

Claims (7)

A retardation film formed by laminating at least one layer including a (meth) acrylic resin layer and a layer including a positive birefringent resin, and having a 90 ° incident light of a scattered light profile of a goniophotometer. In the scattered light intensity measurement of the film, when detecting the scattered light intensity at a position of 130 ° from the light source, the difference in scattered light intensity between the case where the film slow axis is horizontally installed on the sample stage and the case where the film is vertically installed, A retardation film characterized by being 0.05 or less. The retardation film according to claim 1, wherein the (meth) acrylic resin has a lactone ring structure. The retardation film according to claim 2, wherein the lactone ring structure is a lactone ring structure represented by the following general formula (1).

[Wherein R ¹ , R ² and R ³ independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms; the organic residue may contain an oxygen atom] The retardation film according to claim 1, wherein the positive birefringent resin is at least one resin selected from polyether ketone, polyamide, polyester, polyimide, polyamideimide, and polyesterimide. A polarizing plate comprising the retardation film according to any one of claims 1 to 4 on at least one surface. A liquid crystal display device comprising the polarizing plate according to claim 5 on at least one surface of a liquid crystal cell. On the film containing the (meth) acrylic resin according to any one of claims 1 to 3, a laminated film formed by coating a layer containing the positive birefringent resin according to claim 4, A method for producing a retardation film, which is stretched in at least one direction at 120 ° C. or higher.

Images