JP2019200271A - Manufacturing method of optical laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an optical laminated body capable of easily manufacturing an optical laminated body in which generation of wrinkles is suppressed. SOLUTION: A step of applying a solution containing a pressure-sensitive adhesive composition on the surface of a first release film to form a coating film of the pressure-sensitive adhesive composition, and heating the coating film to cure the pressure-sensitive adhesive composition, A step of forming a pressure-sensitive adhesive layer, a step of bonding the first release film to a polarizing plate via the pressure-sensitive adhesive layer to form a laminate, and cutting the laminate to form a sheet of the laminate. And a step of peeling the first release film from the surface of the pressure-sensitive adhesive layer in the sheet to expose the pressure-sensitive adhesive layer, and a step of bonding the second release film to the exposed surface of the pressure-sensitive adhesive layer. And a method for producing an optical laminate, in which the shrinkage ratio of the polarizing plate in the absorption axis direction is 1.00% or less. [Selection diagram] Fig. 7

Description

  The present invention relates to a method for manufacturing an optical laminate.

  The polarizing plate is used as one of optical components that constitute a liquid crystal display device. As a liquid crystal display device, a laminated structure in which polarizing plates are bonded to both surfaces of a liquid crystal panel via an adhesive layer is known.

  Moreover, an image display device typified by a liquid crystal display device or an organic electroluminescence display device is used as a display surface of a portable device intended for outdoor use. A so-called antireflection film is bonded to the display surface of such an image display device as an optical film that suppresses reflection of external light. The antireflection film is a laminate having a polarizing plate and a retardation layer. A structure in which the antireflection film is bonded to the display surface of the image display device via an adhesive layer is known.

  In the following description, a laminate having a polarizing plate and a pressure-sensitive adhesive layer used when the polarizing plate is bonded to a liquid crystal panel or the like may be referred to as an “optical laminate”.

JP 2017-54093 A

  The conventional optical laminated body is manufactured as a sheet by cutting the members into a predetermined shape after the members are laminated together in a roll-to-roll manner. A single wafer optical laminate is usually stored for a certain period of time after being cut and before being used. In such an optical laminated body after a certain period of time, “wrinkles” may occur in the pressure-sensitive adhesive layer. The generated “wrinkles” cause the image of the image display device to be distorted. Therefore, there has been a demand for an optical laminate that suppresses the occurrence of “wrinkles”.

  This invention is made | formed in view of such a situation, Comprising: It aims at providing the manufacturing method of the optical laminated body which can manufacture easily the optical laminated body which suppressed generation | occurrence | production of wrinkles.

  In order to solve the above problems, one embodiment of the present invention includes a step of applying a solution containing an adhesive composition to the surface of a first release film to form a coating film of the adhesive composition; A step of heating the film to cure the pressure-sensitive adhesive composition to form a pressure-sensitive adhesive layer, and a step of bonding the first release film to the polarizing plate through the pressure-sensitive adhesive layer to form a laminate. And cutting the laminate to form a sheet of the laminate; and exposing the adhesive layer by peeling the first release film from the surface of the adhesive layer in the sheet. And a step of laminating a second release film on the exposed surface of the pressure-sensitive adhesive layer, and an optical laminate having a contraction rate in the absorption axis direction of the polarizing plate of 1.00% or less A manufacturing method is provided.

  In 1 aspect of this invention, it is good also as a manufacturing method whose thickness of a said 2nd peeling film is 40 micrometers or more.

  In one aspect of the present invention, the second release film may be a manufacturing method that is 2 μm or more thicker than the first release film.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the optical laminated body which can manufacture easily the optical laminated body which suppressed generation | occurrence | production of wrinkles can be provided.

1 is a schematic cross-sectional view showing an optical laminated body 1. FIG. It is process drawing which shows the manufacturing method of the optical laminated body of this embodiment. It is process drawing which shows the manufacturing method of the optical laminated body of this embodiment. It is process drawing which shows the manufacturing method of the optical laminated body of this embodiment. It is process drawing which shows the manufacturing method of the optical laminated body of this embodiment. It is process drawing which shows the manufacturing method of the optical laminated body of this embodiment. It is process drawing which shows the manufacturing method of the optical laminated body of this embodiment. It is explanatory drawing which shows the measuring method of the creep force between the peeling film and the adhesive layer. It is explanatory drawing which shows the measuring method of the creep force between the peeling film and the adhesive layer.

  Hereinafter, the manufacturing method of the optical laminated body according to the present embodiment will be described with reference to FIGS. In all the drawings below, the dimensions and ratios of the constituent elements are appropriately changed in order to make the drawings easy to see.

[Optical laminate]
FIG. 1 is a schematic cross-sectional view showing an optical laminate 1 produced by the method for producing an optical laminate of this embodiment.

  As shown in FIG. 1, the optical laminate 1 has a polarizing plate 10, a surface protective film 20, an adhesive layer 30, and a release film 42. The release film 42 corresponds to the “second release film” in the present invention.

(Polarizer)
The polarizing plate 10 includes a polarizer 11 and protective films 12 and 13.

(Polarizer)
The polarizer 11 transmits linearly polarized light having a polarization plane in a specific direction. The light that has passed through the polarizer 11 becomes linearly polarized light that vibrates in the direction of the transmission axis of the polarizer. The thickness of the polarizer 11 is, for example, about 1 μm to 80 μm.

  Examples of the polarizer 11 include hydrophilic polymer films such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, and an ethylene / vinyl acetate copolymer partially saponified film, and iodine or a dichroic dye. The thing to which the dyeing | staining process and extending | stretching process by the chromatic substance was given can be used. Further, as the polarizer 11, a polyene-based oriented film such as a dehydrated polyvinyl alcohol product or a dehydrochlorinated polyvinyl chloride product can be used. Among these, the polarizer 11 obtained by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching is preferable because of excellent optical characteristics.

  The dyeing with iodine is performed, for example, by immersing a polyvinyl alcohol film in an aqueous iodine solution. The stretching ratio of uniaxial stretching is preferably 3 to 7 times. The stretching may be performed after the dyeing treatment or may be performed while dyeing. Moreover, you may dye | stain after extending | stretching.

  The polyvinyl alcohol film is subjected to a swelling treatment, a crosslinking treatment, a washing treatment, a drying treatment and the like as necessary. For example, by immersing a polyvinyl alcohol film in water and washing it with water before dyeing, not only can the surface of the polyvinyl alcohol film be cleaned and anti-blocking agents can be washed, but also the polyvinyl alcohol film can be swollen and dyed. Unevenness can be prevented.

  As the polarizer 11, for example, as described in JP-A-2006-170368, a cured film obtained by polymerizing a liquid crystal compound in which a dichroic dye is aligned may be used. As the dichroic dye, those having absorption within a wavelength range of 380 to 800 nm can be used, and an organic dye is preferably used. Examples of the dichroic dye include azo compounds. The liquid crystal compound is a liquid crystal compound that can be polymerized while being aligned, and can have a polymerizable group in the molecule.

(Protective film)
The protective films 12 and 13 are films that are bonded to both surfaces of the polarizer 11 to protect the polarizer 11. The protective films 12 and 13 are bonded to one surface of the polarizer 11 via an adhesive layer or a pressure-sensitive adhesive layer (not shown). In the polarizing plate 10 of this embodiment, the protective films 12 and 13 are bonded to both surfaces of the polarizer 11, but the protective film may be provided only on one surface of the polarizer 11.

  As the protective films 12 and 13, a resin film having optical transparency to visible light can be suitably used.

  Examples of the material for forming the protective films 12 and 13 include triacetyl cellulose (TAC) resin, polycarbonate resin, polyvinyl alcohol resin, polystyrene resin, (meth) acrylate resin, polyolefin resin, and polyarylate resin. , Polyimide resins, polyamide resins and the like. Examples of the polyolefin resin include a cyclic polyolefin resin and a polypropylene resin.

  Furthermore, the protective films 12 and 13 may have a hard coat layer on the surface.

  The protective films 12 and 13 may use the same film or different films.

(Surface protection film)
The surface protective film 20 is a film for protecting the surface of the polarizing plate 10, and is bonded to the surface 10a on the protective film 13 side of the polarizing plate 10 via an adhesive layer (not shown). The surface protective film 20 is peeled after the optical laminated body 1 is bonded to the display surface of a liquid crystal panel or an image display device.

  The surface protective film 20 is made of a thermoplastic resin as a forming material. The material for forming the surface protective film 20 is, for example, a polyolefin resin such as polyethylene resin, polypropylene resin, or cyclic polyolefin resin; polyester resin such as polyethylene terephthalate or polyethylene naphthalate; polycarbonate resin; (meth) acrylic resin Examples thereof include resins.

  In the present specification, “(meth) acrylic resin” represents at least one selected from the group consisting of acrylic resins and methacrylic resins. The same applies to other terms with “(meta)”.

  The thickness of the surface protective film 20 is preferably 5 to 200 μm, more preferably 10 to 150 μm, further preferably 20 to 120 μm, and still more preferably 25 to 100 μm.

(Adhesive layer)
The pressure-sensitive adhesive layer 30 is provided on the surface 10 b of the polarizing plate 10 on the protective film 12 side. The optical laminated body 1 of this embodiment is bonded to a liquid crystal panel or an image display device via an adhesive layer 30.

  The pressure-sensitive adhesive layer 30 is composed of a cured product of a pressure-sensitive adhesive composition containing as a main component (base polymer) a resin such as (meth) acrylic, rubber-based, urethane-based, ester-based, silicone-based, or polyvinylether-based. be able to. Among these, the pressure-sensitive adhesive layer 30 is preferably a cured product of a pressure-sensitive adhesive composition having a base polymer of (meth) acrylic resin excellent in transparency, weather resistance, heat resistance, and the like.

  The pressure-sensitive adhesive composition may be an active energy ray curable type such as an ultraviolet curable type or a thermosetting type, but is preferably a thermosetting type.

  Examples of the (meth) acrylic resin used for the pressure-sensitive adhesive composition include butyl (meth) acrylate, ethyl (meth) acrylate, isooctyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. The polymer which 1 type (s) or 2 or more types of (meth) acrylic acid ester superposed | polymerized can be mentioned.

  The (meth) acrylic resin is preferably copolymerized with a polar monomer. Examples of polar monomers include (meth) acrylic acid, 2-hydroxypropyl (meth) acrylate, hydroxyethyl (meth) acrylate, (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylate, glycidyl ( Mention may be made of monomers having a carboxy group, a hydroxyl group, an amide group, an amino group, an epoxy group and the like, such as (meth) acrylate.

  The pressure-sensitive adhesive composition may be only the base polymer, but preferably contains a crosslinking agent. Examples of the cross-linking agent include a divalent or higher-valent metal ion that forms a carboxylic acid metal salt with a carboxy group; a polyamine compound that forms an amide bond with a carboxy group; Examples thereof include epoxy compounds and polyols that form an ester bond with a carboxy group; polyisocyanate compounds that form an amide bond with a carboxy group. Of these, polyisocyanate compounds are preferred.

  In addition to the base polymer and the crosslinking agent, the pressure-sensitive adhesive composition further contains a compound that polymerizes by heating in addition to the base polymer. The pressure-sensitive adhesive composition may contain a photopolymerization initiator, a photosensitizer, and the like as necessary.

  The pressure-sensitive adhesive composition comprises fine particles for imparting light scattering properties, resin beads, beads such as glass beads, glass fibers, resins other than the base polymer, tackifiers, metal powders, as long as the effects of the invention are not impaired. And other fillers such as inorganic powders, antioxidants, ultraviolet absorbers, dyes, pigments, colorants, antifoaming agents, corrosion inhibitors, photopolymerization initiators and the like.

  The thickness of the pressure-sensitive adhesive layer 30 is preferably 1 μm or more and 40 μm or less, and more preferably 3 μm or more and 25 μm or less. When the thickness of the pressure-sensitive adhesive layer 30 is 3 μm or more and 25 μm or less, the optical layered body 1 can be thinned while maintaining sufficient adhesive force as the pressure-sensitive adhesive layer 30.

(Peeling film)
The release film 42 is a film that protects the surface of the pressure-sensitive adhesive layer 30 until the optical laminate 1 is bonded to the adherend via the pressure-sensitive adhesive layer 30. The release film 42 is composed of a resin film that has been subjected to a release treatment on one side. The release film 42 is bonded to the pressure-sensitive adhesive layer 30 so that the surface on which the above-described release treatment is performed faces the pressure-sensitive adhesive layer 30.

  Examples of the resin constituting the release film 42 include thermoplastic resins such as polyethylene resins such as polyethylene, polypropylene resins such as polypropylene, and polyester resins such as polyethylene terephthalate and polyethylene naphthalate. . The thickness of the release film 42 is preferably 40 μm or more. Further, the thickness of the release film 42 is preferably 100 μm or less.

  Examples of the mold release treatment method include a method of applying silicone oil to the surface of the resin film.

  In addition, the optical laminated body 1 may have a retardation layer such as a λ / 2 plate or λ / 4.

  The optical laminated body 1 manufactured by the manufacturing method of the optical laminated body of this embodiment has the above-described configuration.

[Method for producing optical laminate]
2-7 is process drawing which shows the manufacturing method of the optical laminated body 1 of this embodiment.

  As shown in FIG. 2, first, after applying the liquid 30a containing the pressure-sensitive adhesive composition to the surface of the release film original 41A, the solvent contained in the solution is removed to form a coating film 31 of the pressure-sensitive adhesive composition. . This step corresponds to the “step of forming a coating film” in the present invention. Further, the release film original fabric 41A corresponds to the “first release film” in the present invention.

  In the present specification, the “original fabric” refers to a film before being cut into a desired size. The original fabric may be a long (strip-shaped) film wound up in a roll shape or a sheet film. The long film can have a length in the longitudinal direction of, for example, 100 m or more.

  As the release film original fabric 41A, a resin film having a release treatment on one surface can be used as in the case of the release film 42 described above. As the thermoplastic resin constituting the release film original fabric 41A, the same resin as that used for the release film 42 can be used.

  The liquid 30a includes the pressure-sensitive adhesive composition and an organic solvent that dissolves or disperses the pressure-sensitive adhesive composition. The liquid 30a may be a solution or a dispersion. As the organic solvent, an organic solvent capable of dissolving the base polymer may be appropriately selected according to the composition of the pressure-sensitive adhesive composition to be used.

  In this embodiment, it demonstrates below that a thermosetting adhesive composition is used as an adhesive composition.

  Application methods for the liquid 30a include wire bar coating, roll coating such as reverse coating and gravure coating, die coating, comma coating, lip coating, screen coating, fountain coating, dipping, spraying, etc. It can carry out using a well-known coating method. In FIG. 2, as an example, a method of applying the liquid 30a using the die D is shown.

  Next, as shown in FIG. 3, the coating film 31 is dried and heated to cure the pressure-sensitive adhesive composition constituting the coating film 31, thereby forming a pressure-sensitive adhesive layer 30A. This step corresponds to the “step of forming an adhesive layer” in the present invention.

  Next, as shown in FIG. 4, the release film original fabric 41 </ b> A is bonded to the polarizing plate original fabric 10 </ b> A through the pressure-sensitive adhesive layer 30 </ b> A to form the laminate 2. The polarizing plate original fabric 10A includes a polarizer original fabric 11A, a protective film original fabric 12A, a protective film original fabric 13A, and a surface protective film original fabric 20A. The release film original 41A and the polarizing plate original 10A can be bonded together by, for example, a roll-to-roll method. This step corresponds to the “step of forming a laminate” in the present invention.

  Next, as illustrated in FIG. 5, the stacked body 2 is cut to form a sheet 3 of the stacked body 2. For example, the laminated body 2 is cut by punching the laminated body 2 into a predetermined shape defined by the shape of the cutting blade B using a frame-shaped cutting blade (Thomson blade) B shown in the drawing, or by laser light on the laminated body 2. , And scanning so that the laser beam draws a locus of a desired shape. This step corresponds to the “step of forming a sheet” in the present invention.

  In the sheet 3, the surface protective film 20, the polarizing plate 10, the pressure-sensitive adhesive layer 30, and the release film 41 are laminated in this order. The release film original fabric 41 corresponds to the “first release film” in the present invention. The size of the single wafer is not particularly limited. The length of the long side of the single wafer can be 2 m or less.

  As described above, when the pressure-sensitive adhesive composition constituting the coating film 31 becomes the pressure-sensitive adhesive layer 30A while being cured and contracted, at the interface between the coating film 31 and the polarizing plate raw fabric 10A, A frictional force is generated. As a result, the pressure-sensitive adhesive layer 30A that retains internal stress due to curing shrinkage is obtained. The internal stress in the pressure-sensitive adhesive layer 30 </ b> A is also retained in the pressure-sensitive adhesive layer 30 of the sheet 3.

  In addition, the sheet 3 is often stored for a certain period of time after being cut and used. In such an optical laminated body after a certain period of time, “wrinkles” may occur in the pressure-sensitive adhesive layer. The “predetermined period” from when the sheet 3 is manufactured to when the release film 41 is released is, for example, 1 day or more and 1 year or less.

  When the sheet 3 is rectangular in plan view, for example, if the absorption axis of the polarizing plate 10 in the sheet 3 is in the same direction as the long side direction or the short side direction of the polarizing plate 10, “wrinkles” are likely to occur. Become.

  As a result of the study, the inventors considered that the internal stress of the pressure-sensitive adhesive layer 30 as described above was the cause of “wrinkles” remaining after being bonded to a liquid crystal panel or an image display device. “Wrinkles” occur in the pressure-sensitive adhesive layer. Therefore, in the manufacturing method of the optical laminated body of this embodiment, the following process is further included after storing for a certain period, and “wrinkles” generated in the pressure-sensitive adhesive layer 30 are eliminated.

  Next, as shown in FIG. 6, the release film 41 is peeled from the pressure-sensitive adhesive layer 30 to expose the pressure-sensitive adhesive layer 30. This step corresponds to the “step of exposing the pressure-sensitive adhesive layer” in the present invention.

  Thus, it is thought that the internal stress which the adhesive layer 30 has is released by the peeling film 41 side by peeling the peeling film 41 from the adhesive layer 30. FIG. Thereby, the cause of “wrinkles” of the pressure-sensitive adhesive layer 30 is reduced or eliminated.

  The time from peeling the release film 41 to bonding the release film 42 is preferably 10 seconds or more, and more preferably 30 seconds or more. The time from peeling the release film 41 to laminating the release film 42 may be 1 minute or longer. It is preferable that the time from peeling the release film 41 to bonding the release film 42 is 10 seconds or longer because the internal stress of the pressure-sensitive adhesive layer 30 is easily relaxed.

  Moreover, the time from peeling the release film 41 to bonding the release film 42 is preferably 3 minutes or less. It is preferable that the time from peeling the release film 41 to bonding the release film 42 is 3 minutes or less because it is easy to prevent adhesion of dust and dust to the pressure-sensitive adhesive layer 30.

  Next, as shown in FIG. 7, the release film 42 is bonded to the surface of the pressure-sensitive adhesive layer 30 to obtain the optical laminate 1. This step corresponds to the “step of bonding the second release film” in the present invention. The release film 42 corresponds to the “second release film” in the present invention.

  The contraction rate in the absorption axis direction of the polarizing plate 10 to be used is 1.00% or less. The lower limit of the shrinkage rate in the absorption axis direction of the polarizing plate 10 is not particularly limited, but is usually 0.00% or more and may be 0.50 or more. The contraction rate in the absorption axis direction of the polarizing plate 10 is the thickness of the polarizer 11, the stretching ratio of the polarizer 11, the degree of crosslinking constituting the polarizer 11, the thickness of the protective film bonded to the polarizer 11, and the linear expansion. It can be controlled by adjusting the modulus, elastic modulus, stretching direction and the like.

In the present specification, the “shrinkage rate of the polarizing plate in the absorption axis direction” can be measured as follows.
First, a 10 cm square test piece having sides along the absorption axis and the transmission axis of the polarizing plate is cut out from the polarizing plate. The dimension of the obtained test piece in the absorption axis direction is measured. The obtained value is defined as “initial dimension”.
Next, the test piece is heated for 100 hours in an environment at a temperature of 85 ° C., and the dimension in the absorption axis direction of the heated test piece is measured. The obtained value is defined as “size after heating”.
The value obtained from the following formula is used as the “shrinkage rate in the absorption axis direction” of the polarizing plate using the measured values.
Shrinkage rate in the absorption axis direction of the polarizing plate (%) = 100 × | B−A | / A
(In the formula, A indicates the initial dimension and B indicates the dimension after heating)

  In the manufacturing method of the optical laminate, when the contraction rate in the absorption axis direction of the polarizing plate 10 is large, the adhesive layer 30 is deformed according to the dimensional change of the polarizing plate 10 after the release film 42 is bonded, and “wrinkles”. May occur.

  On the other hand, when a polarizing plate having a contraction rate in the absorption axis direction of 1.00% or less is used, it is difficult for wrinkles due to dimensional changes of the polarizing plate to occur.

  In the present embodiment, it is preferable to use a film 2 μm thicker than the release film 41 as the release film 42. For example, when a 38 μm thick resin film is used as the release film 41, a resin film having a thickness of 40 μm or more is used as the release film 42.

  By using a film that is 2 μm or more thicker than the thickness of the release film 41 as the release film 42, the rigidity of the optical laminate 1 is increased. As a result, the optical laminate 1 is less likely to curl, and the frictional stress between the release film 42 and the pressure-sensitive adhesive layer 30 that causes wrinkles is suppressed.

  As the release film 42, it is preferable to use a film having a creep force between the release film 42 and the pressure-sensitive adhesive layer 30 of 20 N / 10 mm or less, and more preferably 10 N / 10 mm or less. The lower limit value of the creep force is not particularly limited, but is preferably 2N / 10 mm or more. By bonding the release film 42 having such a creep force, the release film 42 and the pressure-sensitive adhesive layer 30 can easily slide with each other, and the generation of “wrinkles” can be suppressed.

  8 and 9 are explanatory diagrams showing a method for measuring the creep force between the release film 42 and the pressure-sensitive adhesive layer 30. FIG.

  First, as shown in FIG. 8, a rectangular test piece TP having a long side of 110 mm and a short side of 15 mm is cut out from the optical laminate 1. Next, the release film 42 is cut at a position of 7.5 mm from the center of the long side direction of the test piece TP to one end side to form a cut C1. Similarly, the other laminated portion excluding the release film 42 is cut at a position of 7.5 mm from the center of the long side direction of the test piece TP to the other end side to form a cut C2.

  Next, as shown in FIG. 9, both ends of the test piece TP in the longitudinal direction are gripped, and the test piece TP is pulled. The creep force is measured using a tensile tester (Autograph AG-1S MO (floor) type, manufactured by Shimadzu Corporation). Both ends of the test piece TP in the longitudinal direction are held by the holding part of the tester, and the test piece TP is pulled at a moving speed of 1 mm / min. The maximum value of the measured stress during the movement of the gripping part until it reaches 5 mm from the start of the test is defined as the creep force.

  The creep force between the pressure-sensitive adhesive layer 30 and the release film 42 can be controlled, for example, by adjusting the amount of the crosslinking agent added to the pressure-sensitive adhesive layer 30. Increasing the crosslinking agent of the pressure-sensitive adhesive layer 30 tends to decrease the creep force, and decreasing the crosslinking agent tends to increase the creep force.

  Further, the creep force can be controlled by adjusting the release treatment of the release film 42. When silicone oil coating is employed as the peeling treatment, the creep force tends to decrease when the silicone oil coating amount is increased, and the creep force tends to increase when the silicone oil coating amount is decreased.

  The manufacturing method of the optical laminated body of this embodiment has the above configuration.

  According to the method for manufacturing an optical laminate having the above-described configuration, an optical laminate that suppresses the generation of wrinkles can be easily produced.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but it goes without saying that the present invention is not limited to such examples. Various shapes, combinations, and the like of the constituent members shown in the above-described examples are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

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

[Evaluation 1]
In Examples, a test piece was cut out from an optical laminate original fabric produced as follows, and evaluation was performed using the obtained test piece.

(Adjustment of water-based adhesive)
3 parts by mass of carboxy group-modified polyvinyl alcohol (trade name “KL-318”, manufactured by Kuraray Co., Ltd.) is dissolved in 100 parts of water, and a polyamide epoxy additive (water-soluble epoxy resin) is added to the resulting aqueous solution ( An aqueous adhesive was prepared by adding 1.5 parts by mass of Taoka Chemical Industry Co., Ltd., trade name “Smile Resin 650 (30)”, 30% solid content aqueous solution).

(Manufacture of polarizing plate raw material)
A protective film original fabric A (thickness: 23 μm) is bonded to one side of the polarizer original fabric (thickness: 8 μm), and a protective film original fabric B (thickness: 52 μm) is bonded to the other surface to obtain polarized light. Sheet raw fabric A was produced. The above-mentioned water-based adhesive was used for bonding each protective film raw fabric and the polarizer.

The polarizer original fabric was a film in which iodine was adsorbed and oriented on a PVA resin film.
The protective film original fabric A was a cyclic olefin resin film. The protective film original fabric A corresponds to “protective film original fabric 12A” in the above-described embodiment.
The protective film original fabric B was a cyclic olefin resin film having a hard coat layer on the surface. The protective film original fabric B corresponds to “protective film original fabric 13A” in the above-described embodiment.

  About the obtained polarizing plate original fabric A, the shrinkage rate of the absorption-axis direction measured by the following method was 0.76%.

<Measurement method>
First, a 10 cm square test piece having sides along the absorption axis and the transmission axis of the original polarizing plate A was cut out from the original polarizing plate A. The dimension in the absorption axis direction of the obtained test piece was measured. The obtained value was defined as “initial dimension”.
Subsequently, the test piece was heated for 100 hours in the environment of 85 degreeC temperature, and the dimension of the absorption axis direction of the heated test piece was measured. The obtained value was defined as “size after heating”.
The values obtained from the following formulas were used as the “shrinkage rate in the absorption axis direction” of the polarizing plate using the measured values.
Shrinkage rate in the absorption axis direction of the polarizing plate (%) = 100 × | B−A | / A
(In the formula, A indicates the initial dimension and B indicates the dimension after heating)

(Preparation of acrylic resin)
In a reaction vessel equipped with a cooling pipe, a nitrogen introduction pipe, a thermometer and a stirrer, 81.8 parts by mass of ethyl acetate as a solvent, 70.4 parts by mass of butyl acrylate as a monomer, 20.0 parts by mass of methyl acrylate, A mixed solution of 8.0 parts by mass of 2-phenoxyethyl acrylate, 1.0 part by mass of 2-hydroxyethyl acrylate, and 0.6 parts by mass of acrylic acid was charged.

  The inside of the reaction vessel was replaced with a nitrogen atmosphere, and the internal temperature of the reaction vessel was raised to 55 ° C. Separately, a solution prepared by dissolving 0.14 parts by mass of azobisisobutyronitrile as a polymerization initiator in 10 parts by mass of ethyl acetate was prepared, and the polymerization initiator solution was placed in a reaction vessel whose internal temperature was 55 ° C. Was added in total. Hold at this temperature for 1 hour after addition of initiator.

(Preparation of pressure-sensitive adhesive composition)
0.5 parts by mass of a crosslinking agent (trade name “Coronate” manufactured by Tosoh Corporation) and 0.5 parts by mass of 3-glycidoxypropyltrimethoxysilane (100 parts by mass of the solid content of the synthesized acrylic resin) Shin-Etsu Chemical Co., Ltd., trade name “KBM-403”), 3.5 parts by mass of compound (15) were blended. Further, 2-butanone was added so that the solid content concentration was 14% by mass.

  The obtained composition was stirred and mixed at 300 rpm for 30 minutes using a stirrer (trade name “Three-One Motor” manufactured by Yamato Scientific Co., Ltd.) to prepare an adhesive composition.

(Preparation of adhesive sheet)
Using an applicator so that the thickness of the pressure-sensitive adhesive layer after drying is 20 μm on the release-treated surface of the polyethylene terephthalate film (release film, thickness: 38 μm) subjected to the mold release treatment Applied. An adhesive sheet was produced by drying at 100 ° C. for 1 minute.

  The release film corresponds to the “release film original 41A” in the above embodiment. The creep force between the pressure-sensitive adhesive layer and the release film was 8.3 N / 10 mm.

(Preparation of surface protection film)
A surface protective film original fabric having an adhesive layer on one surface of the base film was prepared. The base film which the surface protective film has was a polyethylene terephthalate film. The thickness of the base film was 38 μm, and the thickness of the pressure-sensitive adhesive layer was 20 μm. The surface protective film original fabric corresponds to “surface protective film original fabric 20A” in the above embodiment.

(Fabrication of optical laminates)
The adhesive sheet was laminated | stacked on the surface of the protective film original fabric A in the said polarizing plate original fabric A through the adhesive layer.

  Moreover, the surface protective film original fabric was laminated | stacked on the surface of the protective film original fabric B in the said polarizing plate original fabric A through the adhesive layer with which a surface protective film original fabric is equipped, and the optical laminated body original fabric was produced.

  A sheet of rectangular optical laminate having a long side of 110 mm and a short side of 63 mm was cut out from the obtained optical laminate original fabric. The obtained single wafer corresponds to the “single wafer” in the present invention. Moreover, the peeling film which the sheet | seat body of an optical laminated body has corresponds to the "1st peeling film" in this invention. The absorption axis direction of the polarizing plate was parallel to the long side of the sheet.

(Example 1-1)
After peeling off the release film from the sheet of optical laminate obtained as described above, another release film 1 (thickness: 38 μm, long side 110 mm, short side 63 mm) is pasted on the exposed adhesive layer. As a result, an optical laminate of Example 1-1 was obtained. The creep force between the release film 1 and the pressure-sensitive adhesive layer was 9.3 N / 10 mm.

The creep force was measured using the test pieces shown in FIGS.
First, a rectangular test piece having a long side of 110 mm and a short side of 15 mm was cut out from the optical laminate. Next, the release film was cut at a position of 7.5 mm from the center in the long side direction of the test piece to one end side to form a cut. Similarly, the other laminated portion excluding the release film was cut at a position of 7.5 mm from the center in the long side direction of the test piece to the other end side to form a cut.

  Next, both ends in the longitudinal direction of the test piece are held by a holding part of a tensile tester (Autograph AG-1S MO (floor) type, manufactured by Shimadzu Corporation), and the test piece TP is moved at a moving speed of 1 mm / min. pull. The maximum value of the measured stress during the movement of the gripping part until it reached 5 mm from the start of the test was defined as the creep force.

  The release film 1 is a polyethylene terephthalate film having a surface subjected to a release treatment. The release film 1 corresponds to the “second release film” in the present invention.

  The mold release treatment was performed by spraying silicone oil (manufactured by ThreeBond Co., Ltd., Bando 39D) on the surface of the polyethylene terephthalate film. In this example, the creep force was controlled by changing the amount of silicone oil applied. When the silicone oil application amount is relatively decreased, the creep force increases, and when the silicone oil application amount is relatively increased, the creep force decreases.

(Example 1-2)
The release film 2 (thickness: 38 μm, long side 110 mm, short side 63 mm) was bonded to the pressure-sensitive adhesive layer exposed by peeling the release film from the optical laminate obtained as described above. Except for this, an optical layered body of Example 1-2 was obtained in the same manner as Example 1-1. The creep force between the release film 2 and the pressure-sensitive adhesive layer was 8.4 N / 10 mm.

  The release film 2 is a polyethylene terephthalate film having a release treatment applied to the surface. In the mold release process of Example 1-2, the application amount of silicone oil was relatively increased as compared with the mold release process in Example 1-1. The release film 2 corresponds to the “second release film” in the present invention.

(Example 1-3)
The release film 3 (thickness: 38 μm, long side 110 mm, short side 63 mm) was bonded to the adhesive layer exposed by peeling the release film from the sheet of optical laminate obtained as described above. Except for this, an optical layered body of Example 1-3 was obtained in the same manner as Example 1-1. The creep force between the release film 3 and the pressure-sensitive adhesive layer was 13.3 N / 10 mm.

  The release film 3 is a polyethylene terephthalate film having a surface subjected to a release treatment. In the mold release process of Example 1-3, the coating amount of silicone oil was relatively reduced as compared with the mold release process in Example 1-1. The release film 3 corresponds to the “second release film” in the present invention.

(Example 1-4)
The release film 4 (thickness: 50 μm, long side 110 mm, short side 63 mm) was bonded to the pressure-sensitive adhesive layer exposed by peeling off the release film from the optical laminate obtained as described above. Except for this, an optical layered body of Example 1-4 was obtained in the same manner as Example 1-1. The creep force between the release film 4 and the pressure-sensitive adhesive layer was 9.6 N / 10 mm.

  The release film 4 is a polyethylene terephthalate film having a surface subjected to a release treatment. In the mold release process of Example 1-4, the amount of silicone oil applied was set to be equal to that of the mold release process in Example 1-1. The release film 4 corresponds to the “second release film” in the present invention.

(Comparative Example 1)
The optical laminate obtained as described above was used as the optical laminate of Comparative Example 1.

  Each of the obtained optical laminates was left in an environment of a temperature of 23 ° C. and a relative humidity of 55% and an environment of a temperature of 23 ° C. and a relative humidity of 75%, and the presence or absence of “wrinkle” was visually evaluated. At each level, five optical laminates of Examples and Comparative Examples were evaluated (n = 5).

  The left optical laminate was observed from the release film side and visually evaluated. The illuminance at the time of visual evaluation was set to 1000 lx or more. The number of optical laminates in which streaky “wrinkles” were visually recognized in the pressure-sensitive adhesive layer by the reflected light of the fluorescent lamp was evaluated.

  In “Evaluation 1”, a product in which the occurrence of streak-like “wrinkles” could not be confirmed was evaluated as a good product.

  Table 1 shows the results of standing in an environment at a temperature of 23 ° C. and a relative humidity of 55%. Table 2 shows the results of standing in an environment at a temperature of 23 ° C. and a relative humidity of 75%. Tables 1 and 2 show the number of laminates in which “wrinkles” occurred. “Initial” in Tables 1 and 2 means immediately after producing the optical layered body.

As a result of the evaluation, no “wrinkle” of the adhesive layer was confirmed in any of the laminates of Examples 1-1 to 1-4.
On the other hand, in Comparative Example 1 in which the release film was not replaced, “wrinkles” of the adhesive layer were confirmed.

[Evaluation 2]
(Example 2-1-1)
An optical laminate of Example 2-1-1 was produced in the same manner as in Example 1-1, using the polarizing plate A having a contraction rate of 0.76% in the absorption axis direction as the polarizing plate.

(Example 2-1-2)
Using the polarizing plate A as the polarizing plate, an optical laminate of Example 2-1-2 was produced in the same manner as in Example 1-4.

(Example 2-2-1)
An optical laminated body of Example 2-2-1 was produced in the same manner as Example 1-1, except that polarizing plate B having a shrinkage rate of 0.95% in the absorption axis direction was used as the polarizing plate. .

(Example 2-2-2)
An optical laminate of Example 2-2-2 was produced in the same manner as Example 1-4 except that Polarizing Plate B was used as the polarizing plate.

(Comparative Example 2-1)
An optical laminate of Comparative Example 2-1 was produced in the same manner as in Comparative Example 1, using the polarizing plate A as the polarizing plate.

(Comparative Example 2-2)
An optical laminate of Comparative Example 2-2 was produced in the same manner as Comparative Example 1 except that Polarizing Plate B was used as the polarizing plate.

(Comparative Example 2-3-1)
An optical laminate of Comparative Example 2-3-1 was produced in the same manner as Comparative Example 1 except that the polarizing plate C having a shrinkage rate of 1.44% in the absorption axis direction was used as the polarizing plate.

(Comparative Example 2-3-2)
An optical laminate of Comparative Example 2-3-2 was produced in the same manner as Example 1-1 except that Polarizing Plate C was used as the polarizing plate.

  Table 3 shows the results of standing in an environment with a temperature of 30 ° C. and a relative humidity of 85%. Table 3 shows the number of laminates in which “wrinkles” occurred. At each level, six of the laminates of the examples and comparative examples were evaluated.

  As a result of the evaluation, in any of Example 2-1-1 to Example 2-2-2, for Comparative Example 2-1 to Comparative Example 2-3-1, in which the release film is not replaced, respectively. The number of occurrences of “wrinkles” decreased, and improvement was seen.

  In addition, in the laminates of Example 2-1-1 and Example 2-2-1 in which the contraction rate in the absorption axis direction of the polarizing plate is 1.00% or less, the contraction rate in the absorption axis direction of the polarizing plate is 1. The number of occurrences of “wrinkles” was further reduced as compared with the laminate of Comparative Example 2-3-2 exceeding 0.000%.

  From the above, it was confirmed that the present invention is useful.

  DESCRIPTION OF SYMBOLS 1 ... Optical laminated body, 2 ... Laminated body, 3 ... Single wafer body, 10 ... Polarizing plate, 10a, 10b ... Surface, 20 ... Surface protection film, 30 ... Adhesive layer, 30a ... Liquid body, 31 ... Coating film, 41 ... release film (first release film), 42 ... release film (second release film)

Claims (3)

Applying a solution containing the pressure-sensitive adhesive composition on the surface of the first release film, and forming a coating film of the pressure-sensitive adhesive composition;
Heating the coating film to cure the pressure-sensitive adhesive composition and forming a pressure-sensitive adhesive layer;
Bonding the first release film to a polarizing plate via the pressure-sensitive adhesive layer, and forming a laminate;
Cutting the laminate, and forming a sheet of the laminate;
Peeling the first release film from the surface of the pressure-sensitive adhesive layer in the sheet body to expose the pressure-sensitive adhesive layer;
Bonding the second release film to the exposed surface of the pressure-sensitive adhesive layer,
The manufacturing method of the optical laminated body whose shrinkage rate of the absorption-axis direction of the said polarizing plate is 1.00% or less.   The manufacturing method of the optical laminated body of Claim 1 whose thickness of a said 2nd peeling film is 40 micrometers or more.   The method for producing an optical laminate according to claim 1, wherein the second release film is 2 μm or more thicker than the first release film.

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