JP2017026970A - Optical laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate having excellent impact resistance, inspection easiness and productivity as an optical member having a thickness of 100 μm or less, for example, for a polarizing plate and for a retardation plate.SOLUTION: There is provided a laminate formed by bonding a release film having a thickness of 50-125 μm to an optical member having a thickness of 100 μm or less through an adhesive, where inclination of a main orientation axis (orientation angle) of the release film is 12 degrees or less, surface roughness (Ra) of a base material film of the release film is 10 nm or more, and a ratio of the thickness of the release film to the total thickness of the laminate is 25-60%.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a laminate, and more particularly, as an optical component having a thickness of 100 μm or less, for example, for a polarizing plate or a retardation plate, impact resistance, ease of inspection, good productivity. The present invention relates to a laminate.

  Polyester films represented by polyethylene terephthalate and polyethylene naphthalate have excellent mechanical strength, dimensional stability, flatness, heat resistance, chemical resistance, optical properties, etc. It is used in applications.

  However, as the application diversifies, the processing conditions and usage conditions of the polyester film diversify. When used as a release polyester film for polarizing plates, the particle component in the release film is a bright spot when inspecting foreign matter. Thus, problems such as a decrease in inspection accuracy occur.

  In recent years, with the rapid spread of mobile phones and personal computers, the demand for liquid crystal displays (LCDs) that are thinner, lighter, consume less power, and have higher image quality than the conventional display CRT is growing significantly. There is also a remarkable growth in the technology for increasing the screen size of LCDs. As an example of increasing the screen size of LCD, recently, LCD is used for large TV applications of 40 inches or more. An LCD with a large screen is often a bright LCD with a large screen by increasing the luminance of a backlight incorporated in the LCD or incorporating a film for improving the luminance into a liquid crystal unit.

  Further, in such a high-brightness type LCD, components such as a polarizing plate, a retardation plate, or a retardation polarizing plate incorporated in a display have not been a problem at all with conventional low-brightness LCDs. Uneven polarization due to an adhesive layer is becoming a problem. For this reason, in the polarizing plate maker, the adhesive itself may use a more flexible type. As a problem when using a flexible adhesive layer, when it is composed of a roll laminate structure of polarizing plate / adhesive layer / release film, when the slight impact is applied to the roll surface, It may be partially recessed and not restored.

  Furthermore, while preventing foreign matter from entering in the LCD manufacturing process, it is becoming increasingly important to improve inspection accuracy so that even if foreign matter is mixed, it can be reliably recognized as a defect.

  For example, as a defect inspection of a polarizing plate, a visual inspection by a crossed Nicol method is generally used. Further, for a polarizing plate used for a large TV application of 40 inches or more, an inspection by an automatic foreign matter inspection device using the crossed Nicol method is used. Has also been implemented. According to the inspection method, two polarizing plates are set in a quenching state with their orientation principal axes orthogonal to each other, and if there are foreign matters or defects, they appear as bright spots. Therefore, by visual defect inspection or a line sensor camera or the like Automatic defect inspection is possible. Here, the pressure-sensitive adhesive layer is usually provided on the polarizing plate, and a polyester film provided with a release layer is used as the release film for that purpose. When a product having such a configuration is inspected, a crossed Nicols inspection is performed in a state where a release polyester film is sandwiched between two polarizing plates. In general, when a release polyester film is used for this, foreign matter and defects are difficult to see in the crossed Nicols inspection, and it may be easy to miss them.

  Furthermore, in the release film bonded to the polarizing plate, a component is disclosed (see Patent Document 5) in which the inspection property is improved when the retardation value of the polyester film is within a certain range. In recent years, even if the film is used in order to satisfy a further high quality requirement level, the inspection accuracy may be insufficient when an inspection for surely finding defects is performed.

Japanese Patent No. 5281595 JP 2013-167894 A JP 2004-341515 A JP 2012-179870 published Japanese Patent No. 3320904

  The present invention has been made in view of the above circumstances, and the problem to be solved thereof is impact resistance, ease of inspection, production for optical members having a thickness of 100 μm or less, for example, for polarizing plates and for retardation plates. The object is to provide a laminate having good properties.

  As a result of intensive studies in view of the above situation, the present inventor has found that the above problem can be easily solved by a laminate having a specific configuration, and has completed the present invention.

  That is, the gist of the present invention is a laminate in which a release film having a thickness of 50 to 125 μm is bonded to an optical member having a thickness of 100 μm or less via an adhesive, and the inclination of the orientation main axis of the release film. The (orientation angle) is 12 degrees or less, the surface roughness (Ra) of the base film of the release film is 10 nm or more, and the ratio of the thickness of the release film to the total thickness of the laminate is 25 to 60%. It exists in the optical laminated body characterized by being.

  According to the present invention, it is possible to provide a laminate having good impact resistance, inspectability, and good productivity for an optical member having a thickness of 100 μm or less, for example, for a polarizing plate or a retardation plate. The industrial value of the invention is high.

Schematic explanatory drawing showing the configuration of the optical laminate of the present invention

  Polyester film which is a representative film constituting the release film in the present invention (Hereinafter, the present invention will be described using a polyester film as a representative example, but the film used in the present invention is limited to a polyester film) May be a single-layer structure or a laminated structure, for example, it may be a multilayer of 4 layers or more, as long as the gist of the present invention is not exceeded other than a 2-layer or 3-layer structure. There is no particular limitation.

  The polyester used for the polyester film in the present invention may be a homopolyester or a copolyester. In the case of a homopolyester, those obtained by polycondensation of an aromatic dicarboxylic acid and an aliphatic glycol are preferred. Examples of the aromatic dicarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid, and examples of the aliphatic glycol include ethylene glycol, diethylene glycol, and 1,4-cyclohexanedimethanol. Representative polyester includes polyethylene terephthalate (PET) and the like. On the other hand, examples of the dicarboxylic acid component of the copolyester include isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, and oxycarboxylic acid (eg, P-oxybenzoic acid). 1 type or 2 types or more are mentioned, As a glycol component, 1 type or 2 types or more, such as ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1, 4- cyclohexane dimethanol, neopentyl glycol, is mentioned. In any case, the polyester referred to in the present invention refers to a polyester that is usually 60 mol% or more, preferably 80 mol% or more of polyethylene terephthalate or the like which is an ethylene terephthalate unit.

In the present invention, it is preferable to blend particles in the polyester layer mainly for the purpose of imparting slipperiness. The kind of the particle to be blended is not particularly limited as long as it is a particle capable of imparting slipperiness. Specific examples thereof include silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, and phosphoric acid. Examples of the particles include magnesium, kaolin, aluminum oxide, and titanium oxide. Further, the heat-resistant organic particles described in JP-B-59-5216, JP-A-59-217755 and the like may be used. Examples of other heat-resistant organic particles include thermosetting urea resins, thermosetting phenol resins, thermosetting epoxy resins, benzoguanamine resins, and the like. Furthermore, during the polyester production process, it is possible to use precipitated particles in which a part of a metal compound such as a catalyst is precipitated and finely dispersed. On the other hand, the shape of the particles to be used is not particularly limited. Either a rod shape or a flat shape may be used. Moreover, there is no restriction | limiting in particular also about the hardness, specific gravity, a color, etc. These series of particles may be used in combination of two or more as required.

  Moreover, the average particle diameter of the particle | grains to be used is 0.01-3 micrometers normally, Preferably it is the range of 0.01-1 micrometer. When the average particle diameter is less than 0.01 μm, the particles are likely to aggregate and dispersibility may be insufficient. On the other hand, when the average particle diameter exceeds 3 μm, the surface roughness of the film becomes too rough and There may be a problem when a release layer is applied in the process.

  Furthermore, the particle content in the polyester layer is usually in the range of 0.001 to 5% by weight, preferably 0.005 to 3% by weight. When the particle content is less than 0.001% by weight, the slipperiness of the film may be insufficient. On the other hand, when the content exceeds 5% by weight, the transparency of the film is insufficient. There is a case.

  The method for adding particles to the polyester layer is not particularly limited, and a conventionally known method can be adopted. For example, it can be added at any stage of producing the polyester constituting each layer, but preferably a polycondensation reaction may be carried out after the esterification stage or after the transesterification reaction.

  Also, a method of blending a slurry of particles dispersed in ethylene glycol or water with a vented kneading extruder and a polyester raw material, or a blending of dried particles and a polyester raw material using a kneading extruder. It is done by methods.

  In addition to the above-mentioned particles, conventionally known antioxidants, antistatic agents, thermal stabilizers, lubricants, dyes, pigments, and the like can be added to the polyester film in the present invention as necessary.

  The thickness of the base film constituting the release film of the present invention is required to be in the range of 50 to 125 [mu] m in order to improve the handleability in use. When the film thickness is less than 50 μm, the strength as the film laminate is insufficient with the further thinning of the polarizing plate, and the handleability is lowered. On the other hand, when it exceeds 125 μm, it is difficult to increase the winding length of the roll-shaped product, and in continuous production, the replacement frequency of the roll-shaped product is increased and workability is lowered.

  The surface roughness (Ra) of the base film constituting the release film of the present invention is 10 nm or more, preferably 15 nm or more. If Ra is smaller than 10 nm, the blocking property after the release treatment is deteriorated, which is not preferable.

  Next, although the manufacture example of the polyester film which can be utilized suitably by this invention is demonstrated concretely, it is not limited to the following manufacture examples at all.

  First, a method of using the polyester raw material described above and cooling and solidifying a molten sheet extruded from a die with a cooling roll to obtain an unstretched sheet is preferable. In this case, in order to improve the flatness of the sheet, it is necessary to improve the adhesion between the sheet and the rotary cooling drum, and an electrostatic application adhesion method and / or a liquid application adhesion method are preferably employed. Next, the obtained unstretched sheet is stretched in the biaxial direction. In that case, first, the unstretched sheet is stretched in one direction by a roll or a tenter type stretching machine. The stretching temperature is usually 70 to 120 ° C., preferably 80 to 110 ° C., and the stretching ratio is usually 2.5 to 7 times, preferably 2.5 to 3.2 times. Next, the stretching temperature orthogonal to the first stretching direction is usually 70 to 170 ° C., and the stretching ratio is usually 3.0 to 7 times, preferably 3.5 to 6 times, more preferably 5.0 to 6 times. It is. Subsequently, heat treatment is performed at a temperature of 180 to 250 ° C. under tension or under relaxation within 30% to obtain a biaxially oriented film. In the above-described stretching, a method in which stretching in one direction is performed in two or more stages can be employed. In that case, it is preferable to carry out so that the draw ratios in the two directions finally fall within the above ranges.

  The simultaneous biaxial stretching method can also be adopted for the production of the polyester film in the present invention. The simultaneous biaxial stretching method is a method in which the unstretched sheet is usually stretched and oriented in the machine direction and the width direction at 70 to 120 ° C., preferably 80 to 110 ° C., and the stretching ratio is as follows: The area magnification is 4 to 50 times, preferably 7 to 35 times, and more preferably 10 to 25 times. Subsequently, heat treatment is performed at a temperature of 170 to 250 ° C. under tension or under relaxation within 30% to obtain a stretched oriented film. With respect to the simultaneous biaxial stretching apparatus that employs the above-described stretching method, conventionally known stretching methods such as a screw method, a pantograph method, and a linear drive method can be employed.

  Furthermore, a so-called coating stretching method (in-line coating) in which the film surface is treated during the above-described polyester film stretching step can be applied. When a coating layer is provided on a polyester film by a coating stretching method, coating can be performed simultaneously with stretching and the thickness of the coating layer can be reduced according to the stretching ratio, producing a film suitable as a polyester film. it can.

  Next, the release layer which comprises the release film in this invention is demonstrated below.

  The release layer constituting the release film in the present invention preferably contains a curable silicone resin in order to improve the release property. It may be a type mainly composed of a curable silicone resin, or a modified silicone type by graft polymerization with an organic resin such as a urethane resin, an epoxy resin or an alkyd resin may be used as long as the gist of the present invention is not impaired. Also good.

  As the type of the curable silicone resin, any of the curing reaction types such as an addition type, a condensation type, an ultraviolet curable type, an electron beam curable type, and a solventless type can be used. Specific examples include KS-774, KS-775, KS-778, KS-779H, KS-847H, KS-856, X-62-2422, X-62-2461, X manufactured by Shin-Etsu Chemical Co., Ltd. -62-1387, X-62-5039, X-62-5040, KNS-3051, X-62-1496, KNS320A, KNS316, X-62-1574A / B, X-62-7052, X-62-7028A / B, X-62-7619, X-62-7213, manufactured by Momentive Performance Materials YSR-3022, TPR-6700, TPR-6720, TPR-6721, TPR6500, TPR6501, UV9300, UV9425, XS56-A2775, XS56-A2982, UV9430, TPR6600, TPR66 4, TPR6605, SRX357, SRX211, SD7220, SD7292, LTC750A, LTC760A, LTC303E, SP7259, BY24-468C, SP7248S, BY24-452, DKQ3-202, DKQ3-203, manufactured by Toray Dow Corning Co., Ltd. , DKQ3-205, DKQ3-210, and the like. Further, a release control agent may be used in combination to adjust the release property of the release layer.

In the present invention, the curing conditions for forming the release layer on the film are not particularly limited, and when the release layer is provided by off-line coating, usually at 120 to 200 ° C. for 3 to 40 seconds, preferably Is preferably heat-treated at 100 to 180 ° C. for 3 to 40 seconds as a guide. Moreover, you may use together heat processing and active energy ray irradiation, such as ultraviolet irradiation, as needed. In addition, a conventionally well-known apparatus and an energy source can be used as an energy source for hardening by active energy ray irradiation. The coating amount (after drying) of the release layer is usually from 0.005 to 1 g / m ² , preferably from 0.005 to 0.5 g / m ² , more preferably from 0.01 to 5 in terms of coatability. The range is 0.2 g / m ² . When the coating amount (after drying) is less than 0.005 g / m ² , the coating property may be less stable and it may be difficult to obtain a uniform coating film. On the other hand, when the coating is thicker than 1 g / m ² , the coating layer adhesion and curability of the release layer itself may be lowered.

  In the present invention, conventionally known coating methods such as reverse gravure coating, direct gravure coating, roll coating, die coating, bar coating, curtain coating and the like can be used as a method for providing a release layer on the film. Regarding the coating method, there is a description example in “Coating method” published by Yasuharu Harasaki in 1979.

  Regarding the release film in the present invention, a coating layer such as an adhesive layer, an antistatic layer, and an oligomer precipitation preventing layer may be provided on the film surface on which the release layer is not provided as long as the gist of the present invention is not impaired. .

  Further, the film constituting the release film may be subjected to surface treatment such as corona treatment or plasma treatment in advance.

  The release film thus obtained may have an inspection process with optical evaluation, and in order to reduce the occurrence of foreign matter and light interference color, the inclination (orientation angle) of the orientation axis of the release film is optimized. Is needed. Therefore, in the release film, the inclination (orientation angle) of the orientation main axis needs to be 12 degrees or less. The orientation angle is preferably less than or equal to a degree. When the orientation angle is larger than 12 degrees, in the inspection process accompanied by optical evaluation, the light interference color becomes easy to see and foreign matter inspection becomes difficult.

  As a specific means for satisfying the range of the inclination (orientation angle) of the orientation main axis of the release film of the present invention, for example, the stretching ratio and the stretching within the range that does not impair the productivity in the stretching conditions during film formation. Examples of the method include adjusting the temperature.

  Next, the adhesive layer bonded to the release layer of the release film in the present invention will be described below. The adhesive layer in the present invention means a layer composed of a material having adhesiveness, and conventionally known materials can be used as long as the gist of the present invention is not impaired. As one specific example, the case where an acrylic adhesive is used will be described below.

  In the present invention, the acrylic pressure-sensitive adhesive means a pressure-sensitive adhesive layer containing, as a base polymer, an acrylic polymer formed using an acrylic monomer as an essential monomer component. The acrylic polymer has (meth) acrylic acid alkyl ester and / or (meth) acrylic acid alkoxyalkyl ester having a linear or branched alkyl group as an essential monomer component (more preferably as a main monomer component). ) It is preferably an acrylic polymer to be formed. Furthermore, the acrylic polymer is preferably an acrylic polymer formed using (meth) acrylic acid alkyl ester and acrylic acid alkoxyalkyl ester having a linear or branched alkyl group as essential monomer components.

  Next, in the laminate (optical member (for example, polarizing plate) / adhesive layer / release film) configuration using the release film in the present invention, the acrylic adhesive composition at the time of forming the adhesive layer, which is a structural unit thereof For example, by replacing voids existing between the surface protective layer, the touch panel, and the display surface of the image display unit with a transparent adhesive sheet having a refractive index close to that of the optical member compared to air, for example. In consideration of improving the light transmittance and suppressing the decrease in luminance and contrast of the image display device, it is preferable to design the pressure-sensitive adhesive layer itself flexibly.

  From this viewpoint, the loss tangent tan δ at a frequency of 1 Hz and a temperature range of 40 ° C. to 100 ° C. is preferably 0.5 or more with respect to the adhesive layer constituting the laminate using the release film in the present invention. When the loss tangent tan δ is less than 0.5, for example, when filling a gap existing between optical members for touch panel applications, the filled adhesive layer does not reach every corner, and peels off or floats at the end. May cause problems.

  The thickness of the pressure-sensitive adhesive layer constituting the laminate using the release film in the present invention is preferably in the range of 5 to 50 μm in consideration of workability or pressure-sensitive adhesive performance. If the thickness of the adhesive layer is less than 5 μm, it may be difficult to obtain a desired adhesive force, and may cause problems such as easy peeling in a scene that does not need to be peeled. On the other hand, when the thickness of the pressure-sensitive adhesive layer exceeds 50 μm, the pressure-sensitive adhesive force is in a saturated state, and problems such as protrusion of the pressure-sensitive adhesive layer may occur in handling.

  In the present invention, the counterpart optical member (for example, polarizing plate) to which the release film is attached is intended to have a thickness of 100 μm or less from the viewpoint of reducing the thickness or reducing the weight in various applications. The lower limit of the thickness is not particularly limited, but is preferably 50 μm or more in consideration of handleability and the like. When the polarizing plate thickness is less than 50 μm, the handleability may be difficult. On the other hand, when it exceeds 100 μm, it is difficult to reduce the thickness or weight depending on the application.

  Next, as a representative example of the optical member in the present invention, the production of a polarizing plate will be described below. In the present invention, the polarizing plate can be produced by employing a conventionally known method.

  In the present invention, a polarizing plate configuration in which a protective film is bonded to both surfaces of a film of a polyvinyl alcohol resin containing a dichroic dye (sometimes referred to as a polarizer) via an adhesive layer is specifically shown. Take an example.

  A conventionally well-known method can be employ | adopted regarding the polarizer which comprises the polarizing plate used in this invention. For example, as described in Patent Document 3, the film can be obtained by swelling a polyvinyl alcohol resin film and then stretching the film while dyeing with dichroic dye such as iodine or dichroic dye. it can.

  In this invention, a conventionally well-known film can be used for the protective film which comprises a polarizing plate. Specific examples include Fujitac Series (TAC (triacetylcellulose) film (TD40, TD40UF, etc.)), Konica Minolta Opto TAC (triacetylcellulose) film (KC4UA, KC6UA, KC8UX2MW, etc.), Optes, Inc. Examples include the Zeonore series and the JSR Arton series. For example, there is description in Patent Document 2.

  Moreover, in the release film in the present invention, the ratio of the thickness of the release film to the total thickness of the laminate is 25 to 60%. It is necessary to make it good. When the ratio is less than 25%, for example, when a flexible adhesive layer is used, the adhesive layer is deformed when an impact from the outside is received from the side of the release film, such as during transportation. Will not be restored. On the other hand, if it exceeds 60%, it is difficult to handle because the mechanical strength of the release film is too strong.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded. The measuring method used in the present invention is as follows.

(1) Measurement of intrinsic viscosity (dl / g) of polyester Weigh accurately 1 g of polyester from which other polymer components and pigments incompatible with polyester have been removed, and mix phenol / tetrachloroethane = 50/50 (weight ratio) 100 ml of solvent was added and dissolved, and measurement was performed at 30 ° C.

(2) Measurement of average particle diameter (d ₅₀ : μm) Integration (weight basis) 50% in equivalent spherical distribution measured using centrifugal sedimentation type particle size distribution measuring device (SA-CP3 type manufactured by Shimadzu Corporation) Was the average particle size.

(3) Measurement of orientation (orientation angle) of orientation axis of release film Using a polarization microscope manufactured by Carl Zeiss, the orientation of the polyester film is observed, and the orientation of the orientation axis in the polyester film plane is the width of the polyester film. The orientation angle was determined by measuring the number of tilts with respect to the direction. This measurement was carried out at a total of three locations on the center and both ends of the film, and the largest orientation angle value among the three locations was taken as the maximum orientation angle.

(4) Blocking property of release film A release film having a winding length of 10,000 m was obtained, stored in a warehouse for 1 month, and then the blocking state in the adhesive processing step was determined according to the following criteria.
○: Processing was possible without problems ×: Processing stopped due to an appearance abnormality due to blocking confirmed from the lower volume of about 2000m

(5) Ease of inspection (practical property substitution evaluation)
When producing a polarizing plate by the following method, the black metal powder (foreign matter) with a magnitude | size of 50 micrometers or more was mixed between the adhesion layer and the release film so that it might become 50 piece / m < ² >. A polarizing plate for inspection is superimposed on the release film with a polarizing plate mixed with foreign matter thus obtained so that the orientation axis is orthogonal to the width direction of the release film, and white light is irradiated from the polarizing plate side. Then, it was visually observed from a polarizing plate for inspection, and it was evaluated according to the following criteria whether foreign matter mixed between the pressure-sensitive adhesive and the release film could be found under crossed Nicols. In the observation, A4 size samples were cut out from a total of three locations in the center and both ends in the width direction of the obtained film. Judgment is based on the following criteria.
<Criteria>
○: Good foreign body recognition (a level that is practically acceptable)
X: Foreign object cognitive deficiency (practical problem level)

<Manufacture of polarizing plate>
While a polyvinyl alcohol film having a thickness of 75 μm is dyed with an aqueous solution containing 0.032 parts by weight iodine and 0.2 parts by weight potassium iodide with respect to 100 parts by weight of water after pure swelling at 30 ° C., the draw ratio (final) is It extended | stretched so that it might become 6 times. After this stretched film was dried at 40 ° C. for 1 minute, a polarizer having a thickness of 25 μm was obtained. Next, a polyvinyl alcohol-based water-soluble adhesive was provided on both surfaces of the obtained polarizer so that the thickness (after drying) was 5 μm, and then a TAC film (thickness 25 μm) was bonded thereon, and a thickness of 85 μm was obtained. A polarizing plate was obtained.

<Manufacture of laminate (release film with polarizing plate)>
On the release layer of the obtained release film, a coating liquid composed of the following adhesive layer forming composition was applied, and then heat-treated at 100 ° C. for 5 minutes using a hot-air circulation furnace, and the coating amount An adhesive layer (after drying) of 25 μm was obtained.

<Adhesive layer forming composition>
Acrylate ester copolymer (Mw = 540000 Mn = 67000 Mw / Mn = 8) obtained by random copolymerization of three components of 75 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of vinyl acetate, and 5 parts by mass of acrylic acid. An adhesive layer was formed by mixing 20 g of 4-phenylbenzophenone as a photopolymerizable initiator with respect to 1 kg of (Tg-50 ° C.). Next, a polarizing plate was bonded to the exposed adhesive layer surface to obtain a laminate.

(6) Impact resistance evaluation (practical property substitution evaluation)
Based on JIS K 5600-5-3, a DuPont impact tester equipped with a ¼ inch iron ball was used. Place the test film laminate on the sample stage so that the release film side is the upper surface, drop a 100 g weight from a height of 30 cm, visually observe the degree of deformation of the adhesive layer of the test piece, and make the following judgment Judgment was made based on the criteria.
<Criteria>
○: Good with no deformation of adhesive layer (practical level)
X: Deformation of the adhesive layer is confirmed and does not restore to the original state (practically problematic level)

(7) Productivity evaluation (practical property substitution evaluation)
Using the release films obtained in Examples and Comparative Examples, the productivity when continuously producing polarizing plates was determined according to the following criteria.
<Criteria>
○: In the release film of roll products, the replacement frequency is low and the productivity is good (practically no problem level)
X: In the release film of a roll product, the frequency of replacement is high and the productivity is lowered (practically problematic level)

(8) Comprehensive evaluation (practical property substitution evaluation)
Using the release films produced in Examples and Comparative Examples, comprehensive evaluation was performed according to the following criteria for each evaluation item of blocking property, impact resistance, ease of inspection, and productivity.
<Criteria>
○: Blocking property, impact resistance testability, and productivity are all ○ (practical level)
Δ: At least one of blocking property, impact resistance, ease of inspection, and productivity is Δ (a level that may cause a problem in practical use).
×: At least one of blocking property, impact resistance, visibility after heat treatment, inspection ease, and productivity is × (practically problematic level)

The polyester used in the examples and comparative examples was prepared as follows.
<Manufacture of polyester>
Production Example 1 (Polyester A1)
100 parts of dimethyl terephthalate, 60 parts of ethylene glycol and 0.09 part of magnesium acetate tetrahydrate are placed in a reactor, the temperature is raised by heating, methanol is distilled off, transesterification is performed, and 4 hours are required from the start of the reaction. The temperature was raised to 230 ° C. to substantially complete the transesterification reaction. Next, after adding 0.04 part of ethylene glycol slurry ethyl acid phosphate and 0.03 part of antimony trioxide, the temperature reached 280 ° C. and the pressure reached 15 mmHg in 100 minutes. It was 0.3 mmHg. After 4 hours, the system was returned to normal pressure to obtain polyester A1 having an intrinsic viscosity of 0.62.

Production Example 2 (Polyester A2)
A polyester A2 having an intrinsic viscosity of 0.57 was obtained in the same manner as in Production Example 1 except that 0.3 part of silica particles having an average particle size of 2.5 μm was added in Production Example 1.

Production Example 3 (Production of polyester film F1)
The raw materials blended with 50% and 50% of polyethylene terephthalate A1 and A2 are used as the surface layer raw material, and the raw material of polyethylene terephthalate A1 = 100% is supplied as the raw material of the intermediate layer to two vented extruders. After feeding to an extruder with melt and extruding at 290 ° C., an amorphous film having a thickness of about 1300 μm was obtained by cooling and solidifying on a cooling roll having a surface temperature set to 40 ° C. using an electrostatic application adhesion method. . The film was stretched 2.8 times in the machine direction at 85 ° C., then stretched 5.2 times in the transverse direction at 100 ° C., and heat-treated at 225 ° C. to obtain a thickness of 75 μm (thickness ratio = 5 μm / 65 μm / 5 μm). ) Polyester film F1 was obtained.

Production Example 5 (Production of Polyester Film F2) to Production Example 12 (Production of Polyester Film F9)
As shown in Table 1 below, the production conditions were changed to obtain each polyester film.

Example 1:
<Manufacture of release film>
In the polyester film F1 having a thickness of 75 μm, the application of the following release layer composition on the coating layer is performed offline by a reverse gravure coating method so that the coating amount (after drying) is 0.1 g / m ^2. After coating on the layer, heat treatment was performed at 120 ° C. for 30 seconds.
(Releasing layer composition)
Curing type silicone resin (KS-847H: manufactured by Shin-Etsu Chemical) 100 parts Curing agent (PL-50T: manufactured by Shin-Etsu Chemical) 1 part MEK / toluene mixed solvent (mixing ratio is 1: 1) 1500 parts

Examples 2-5:
In Example 1, it manufactured like Example 1 except having changed the kind of release film as shown in following Table 1-Table 2, and obtained the release film.

Comparative Examples 1-4:
In Example 1, it manufactured like Example 1 except having changed the kind of release film as shown in following Table 1-Table 2, and obtained the release film.

  The optical layered body of the present invention can be suitably used particularly for a thin polarizing plate having a thickness of 100 μm or less.

DESCRIPTION OF SYMBOLS 10 Laminated body 11 Optical member 12 Adhesion layer 13 Optical member 14 Film

Claims (1)

A laminated body in which a release film having a thickness of 50 to 125 μm is bonded to an optical member having a thickness of 100 μm or less via an adhesive, and an inclination (orientation angle) of an orientation main axis of the release film is 12 degrees or less. The surface roughness (Ra) of the base film of the release film is 10 nm or more, and the ratio of the thickness of the release film to the total thickness of the laminate is 25 to 60%. Laminated body.