WO2010035906A1

WO2010035906A1 - Method for manufacturing composite polarizing plate

Info

Publication number: WO2010035906A1
Application number: PCT/JP2009/067294
Authority: WO
Inventors: 松本寿和
Original assignee: 住友化学株式会社
Priority date: 2008-09-29
Filing date: 2009-09-28
Publication date: 2010-04-01

Abstract

Disclosed is a method for manufacturing a composite polarizing plate, comprising the step of laminating a transparent protective film onto one side surface of a polarizing film, laminating a releasable adhesive film on the opposite side surface of the polarizing film to prepare a polarizing plate with a transparent protective film on one side surface thereof, the step of cutting the polarizing plate with a transparent protective film on one side thereof along the direction of the length in accordance with the size of a phase difference film, and the step of removing the releasable film of the polarizing plate with a transparent protective film on one side surface thereof cut in the above step and laminating the polarizing film surface onto a phase difference film with an epoxy resin composition containing an epoxy resin curable by irradiation of active energy ray or heating.

Description

Manufacturing method of composite polarizing plate

The present invention relates to a method for producing a composite polarizing plate.

Liquid crystal display devices are used in various display devices by taking advantage of low power consumption, operation at low voltage, light weight and thinness. This liquid crystal display device is composed of many optical members such as a liquid crystal cell, a polarizing plate, a retardation film, a light collecting sheet, a diffusion film, a light guide plate, and a light reflecting sheet. Therefore, by improving the number of films or sheets constituting these optical members and reducing the film thickness, it is possible to improve the production efficiency and brightness of the liquid crystal display device and to reduce the weight and thickness. Such research is actively conducted.
As a means for reducing the number of constituent films and sheets and reducing the thickness of a liquid crystal display device, a technique is known in which a protective film on one side of a polarizing plate is also used as a retardation film. For example, in JP-A-8-43812 (Patent Document 1), in a polarizing plate in which protective films are laminated on both surfaces of a polarizing film, at least one of the protective films is a cyclic olefin resin having a function of a retardation film. It is disclosed that it comprises. JP-A-9-325216 (Patent Document 2) discloses that at least one of the transparent protective layers of the polarizing film is composed of a birefringent film (retardation film). Yes.
On the other hand, one of the functions required for the retardation film is to optically compensate for the retardation due to the birefringence of the liquid crystal cell equally in the front direction and the oblique direction. Therefore, the angle dependency of the phase difference value is a very important optical characteristic.
Therefore, various retardation films having a substantially constant retardation value regardless of the angle have been proposed. For example, in Japanese Patent Laid-Open No. 2-160204 (Patent Document 3), the intrinsic birefringence is positive, By stretching a film in which molecules are oriented in the normal direction of the film surface, a phase difference film in which the phase difference at normal incidence and the phase difference at incidence from a direction inclined by 40 ° from the normal is almost the same is obtained. It is disclosed. The retardation film has an in-plane slow axis direction, a refractive index in the in-plane fast axis direction and the thickness direction respectively _n x, when the _{n y} and _{n _z,} a relationship _n _x> n _z> n _y Show.
As a method for producing a retardation film which satisfies a relation of the _{_{_{n x> n z> n y}}} , in Japanese Laid-5-157911 (Patent Document 4), by bonding a shrinkable film to one or both surfaces of a resin film A method of forming a laminate and subjecting the laminate to heat stretching is disclosed. This method shrinks the resin film in the direction perpendicular to the stretching axis at the same time as stretching, causing orientation in the thickness direction (Z direction), and the refractive index distribution of the resin film changes greatly before and after stretching. I am letting. For this reason, the resin film used in this production method is preferably one that easily causes a phase difference at a low stretch ratio, and conventionally, for example, a polycarbonate resin film, a polyarylate resin film, and a polysulfone resin film, Aromatic resin films have been used.
Japanese Patent Application Laid-Open No. 7-230007 (Patent Document 5) discloses a film having heat shrinkability on at least one surface of a uniaxially stretched thermoplastic resin film, and the direction of the heat shrink axis of the thermoplastic resin film. It is disclosed that a retardation film is produced by bonding and heat shrinking so as to be orthogonal to the stretching axis direction. In the retardation film thus obtained, molecules are oriented in the thickness direction. This method is also oriented in the thickness direction by utilizing the shrinkage of the uniaxially stretched thermoplastic resin film accompanying the heat shrinkage of the heat shrinkable film, so that mainly the aromatic resin film that easily develops the phase difference. Has been applied.
However, since the aromatic resin film has a large absolute value of the photoelastic coefficient, the phase difference is likely to change with respect to the stress. For this reason, when exposed to a high temperature in a state where the liquid crystal cell and the polarizing film are bonded and disposed, the retardation value may deviate from the design value due to the contraction stress of the polarizing film, or the heat of the backlight in the liquid crystal display device. In some cases, the unevenness of the phase difference value may occur due to the unevenness of the stress caused by the above-described problem, which deteriorates the display characteristics.
On the other hand, since aliphatic resin films such as cyclic olefin resin films have a small absolute value of the photoelastic coefficient, in recent years, there has been an increasing trend to apply them to retardation films. However, since an aliphatic resin film generally does not easily develop a retardation, a desired retardation value can be obtained even if the stretching ratio is increased, as well as a low stretching ratio such as an aromatic resin film. was difficult. In particular, it is difficult to align the film so that a predetermined retardation value can be obtained in the thickness direction as well as in the stretching axis direction, and the aliphatic resin film is applied to the methods described in Patent Document 4 and Patent Document 5. There was a limit.
Therefore, in JP-A-2006-72309 (Patent Document 6), a shrinkable film having a large shrinkage rate in the width direction is bonded to one side or both sides of a cyclic olefin-based resin film, and an in-plane retardation value is 100. A method of heating and stretching so that a coefficient (N _z coefficient) represented by (n _x −n _z ) / (n _x −n _y ) is 0.1 to 0.9 nm is disclosed. . Here, _nx , _ny and _nz have the meanings as defined above. According to this method, the expression was hardly cycloolefin resin film of the phase difference, also oriented in the thickness direction with the stretching axis direction, is possible to produce a retardation film which satisfies a relation of _{n _x>} n _z> n _y it can.
However, the retardation film satisfying the relation of the cyclic olefin based resin film made of olefin resin film containing n _{_x>} n _z> n _y, in order to undergo the shrinking step in the production process, the polarization width of fabrication can film There are cases where the width is smaller than the width of the film, and the conventional method for producing a polarizing plate has a problem that the productivity is remarkably lowered. That is, in this case, when a polarizing plate and a retardation film having a smaller width than the polarizing plate are bonded together, a polarizing plate portion where the retardation film is not bonded is generated. On the other hand, in order to cut the polarizing plate into a predetermined shape to be bonded to the liquid crystal cell, it is usually cut at a right angle or an oblique angle with respect to the longitudinal direction, and then cut again into the predetermined shape. The polarizing plate part where the film is not bonded is discarded. Furthermore, productivity is significantly reduced by adding a polarizing plate portion to which the retardation film is not bonded to the cutting length.
Furthermore, when the retardation film made of a cyclic olefin film is used so as to serve also as a protective film for the polarizing film, the adhesiveness to the polarizing film may be inferior.

An object of the present invention is to provide a method for producing a composite polarizing plate excellent in adhesion between a polarizing film and a retardation film with high productivity, which is formed by laminating a polarizing plate and a retardation film having a smaller width than the polarizing plate. There is to do.
In order to achieve the above object, the present invention provides a first production method and a second production method of a composite polarizing plate.
In the first production method of the composite polarizing plate of the present invention, (A) a transparent protective film is bonded to one side of a polarizing film, an adhesive peelable film is bonded to the opposite side, and single-sided transparent protection is performed. A step of producing a polarizing plate with a film, (B) a step of cutting the polarizing plate with a single-sided transparent protective film along the longitudinal direction according to the size of the retardation film, and (C) the step (B) The epoxy resin composition containing an epoxy resin that removes the peelable film of the polarizing plate with the single-sided transparent protective film cut in step) and cures the polarizing film surface and the retardation film by irradiation with active energy rays or heating. And a step of pasting using the method.
In the first production method of the present invention, a phase difference film, and its in-plane slow axis direction, the in-plane fast axis direction and the refractive index in the thickness direction respectively n _x, and n _y and n _z, thickness d , An olefin resin film satisfying the formulas (1) and (2) with respect to light having a wavelength of 590 nm is preferable.
_{_{100nm ≦ (n x -n y)}} × d ≦ 300nm (1)
_{_{0.1 ≦ (n x -n z)}} / (n x -n y) ≦ 0.7 (2)
In the first production method of the present invention, the olefin resin film is preferably made of a resin mainly containing a structural unit derived from an alicyclic olefin.
In the first production method of the present invention, the retardation film preferably has a width that is 10% or more smaller than the width of the polarizing plate with the one-side transparent protective film.
In the first production method of the present invention, the epoxy resin preferably contains a compound having at least one epoxy group bonded to an alicyclic ring in the molecule.
In the first production method of the present invention, the thickness of the transparent protective film is preferably 20 to 300 μm.
The second production method of the composite polarizing plate of the present invention is as follows. (A) A transparent protective film is bonded to one side of a polarizing film, an adhesive peelable film is bonded to the opposite side, and single-sided transparent protection is performed. A step of producing a polarizing plate with a film, (B) a step of cutting the polarizing plate with a single-sided transparent protective film along the longitudinal direction according to the width of the retardation film, and (C) the peelable film. The step of removing from the polarizing film surface, (D) on the one side of the retardation film, or the polarizing film surface of the polarizing plate with the single-side transparent protective film that has undergone the step (C) Including a step of laminating a pressure-sensitive adhesive layer exhibiting storage elastic modulus, and (E) a step of bonding the retardation film to the polarizing film surface from which the peelable film has been removed via the pressure-sensitive adhesive layer. With features That.
In the 2nd manufacturing method of this invention, a process (A), a process (B), a process (C), a process (D), and a process (E) are included in this order, and an adhesive layer is a process (D). A case where the film is laminated on the polarizing film surface of the polarizing plate with the single-sided transparent protective film after the step (C) is mentioned as one of preferable modes (hereinafter, this mode is referred to as “first mode”). ).
In the 2nd manufacturing method of this invention, a process (A), a process (C), a process (D), a process (B), and a process (E) are included in this order, and an adhesive layer is a process (D). In addition, when laminated on the polarizing film surface of the polarizing plate with a single-sided transparent protective film that has undergone the step (C), it may be mentioned as one of preferred embodiments (hereinafter referred to as “second embodiment”).
In the second production method of the present invention, the step (A), the step (B), the step (C) and the step (E) are included in this order. In the step (D), the pressure-sensitive adhesive layer is a retardation film. A mode of laminating on one side is also mentioned as one of the preferred modes (hereinafter referred to as “third mode”).
In the second production method of the present invention, a phase difference film, and its in-plane slow axis direction, the in-plane fast axis direction and the refractive index in the thickness direction respectively n _x, and n _y and n _z, thickness d , An olefin resin film satisfying the formulas (1) and (2) with respect to light having a wavelength of 590 nm is preferable.
_{_{100nm ≦ (n x -n y)}} × d ≦ 300nm (1)
_{_{0.1 ≦ (n x -n z)}} / (n x -n y) ≦ 0.7 (2)
In the second production method of the present invention, the olefin-based resin film is preferably made of a resin mainly containing a structural unit derived from an alicyclic olefin.
In the second production method of the present invention, the retardation film preferably has a width that is 10% or more smaller than the width of the polarizing plate with a single-sided transparent protective film.
In the 2nd manufacturing method of this invention, it is preferable to adhere | attach the said polarizing film and a transparent protective film with the water-soluble adhesive containing a polyvinyl alcohol-type resin and an epoxy resin.
Furthermore, in the second production method of the present invention, the polarizing film and the transparent protective film are bonded with an adhesive made of a solvent-free resin composition containing an epoxy resin that is cured by irradiation with active energy rays or heating. It is preferable. In this case, it is preferable that the epoxy resin contains a compound having at least one epoxy group bonded to an alicyclic ring in the molecule.
In the second production method of the present invention, the thickness of the transparent protective film is preferably 20 to 300 μm.
In the second production method of the present invention, the pressure-sensitive adhesive layer preferably has a thickness of 1 to 40 μm.
According to the method for producing a composite polarizing plate of the present invention, the polarizing plate with a single-sided transparent protective film is cut along the longitudinal direction according to the size of the retardation film before being bonded to the retardation film, and the retardation is obtained. By dividing into a polarizing plate with a single-sided transparent protective film to be bonded to a film and a polarizing plate with a single-sided transparent protective film that is not bonded to a retardation film, productivity is not reduced. Furthermore, since the part which does not bond with the phase difference film of the polarizing plate with a single-sided transparent protective film can be used for another product, the whole productivity improves remarkably.
Moreover, by sticking the peelable film which has adhesiveness to the polarizing film side of the polarizing plate with a single-sided transparent protective film to be cut, it is possible to bond the transparent protective film and the polarizing film or the polarizing film in the cutting. Damage can be prevented.

(Polarizing film)
The polarizing film used in the method for producing a composite polarizing plate of the present invention has a function of selectively transmitting unidirectional linearly polarized light from natural light. For example, an iodine polarizing film in which iodine is adsorbed and oriented on a polyvinyl alcohol film, a dye polarizing film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol film, and a dichroic dye in a lyotropic liquid crystal state Examples thereof include a coating type polarizing film coated, oriented and fixed. These iodine-based polarizing films, dye-based polarizing films, and coating-type polarizing films have a function of selectively transmitting one direction of linearly polarized light from natural light and absorbing the other direction of linearly polarized light. It is called a type polarizing film.
The polarizing film used in the production method of the present invention has a function of selectively transmitting one direction of linearly polarized light from natural light and reflecting or scattering another direction of linearly polarized light as well as the above-described absorption polarizing film. What is called a reflective polarizing film or a scattering polarizing film may be used. Moreover, the polarizing film specifically mentioned here is not necessarily limited to these, What is necessary is just to have a function which selectively permeate | transmits the linearly polarized light of a certain one direction from natural light. Among these polarizing films, it is preferable to use an absorptive polarizing film having excellent visibility, and among them, it is more preferable to use an iodine polarizing film having excellent polarization degree and transmittance as the polarizing film.
The polyvinyl alcohol resin used for the polyvinyl alcohol film can be obtained by saponifying a polyvinyl acetate resin. Examples of the polyvinyl acetate resin include, in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate, copolymers with other monomers copolymerizable with vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, unsaturated sulfonic acids, olefins and vinyl ethers.
The saponification degree of the polyvinyl alcohol resin is usually 85 to 100 mol%, and more preferably 98 to 100 mol%. The polyvinyl alcohol-based resin may be modified. For example, polyvinyl formal modified with aldehydes, polyvinyl acetal, polyvinyl butyral, and the like are also used. The degree of polymerization of the polyvinyl alcohol-based resin is usually about 1000 to 10,000, and preferably about 1500 to 10,000.
What formed such a polyvinyl alcohol-type resin into a film is used as a raw film of a polarizing film. The method for forming a polyvinyl alcohol-based resin is not particularly limited, and can be formed by a known method. The thickness of the polyvinyl alcohol-based raw film is not particularly limited, but is, for example, about 2 to 150 μm.
The polarizing film is usually a humidity adjusting step for adjusting the moisture of the raw film made of the polyvinyl alcohol resin as described above, a step of uniaxially stretching the polyvinyl alcohol resin film, and the polyvinyl alcohol resin film with a dichroic dye. It is manufactured through a process of dyeing and adsorbing the dichroic dye, a process of treating the polyvinyl alcohol resin film on which the dichroic dye is adsorbed and oriented with an aqueous boric acid solution, and a step of washing with water after the treatment with the aqueous boric acid solution. The
Uniaxial stretching may be performed before dyeing with a dichroic dye, may be performed simultaneously with dyeing, or may be performed after dyeing. When uniaxial stretching is performed after dyeing with a dichroic dye, the uniaxial stretching may be performed before boric acid treatment or during boric acid treatment. Moreover, it is also possible to perform uniaxial stretching in these several steps. In uniaxial stretching, it may be uniaxially stretched between rolls having different peripheral speeds, or may be uniaxially stretched using a hot roll. Further, it may be dry stretching such as stretching in the air, or may be wet stretching in which stretching is performed in a state swollen with a solvent. The draw ratio is usually 4 to 8 times. The thickness of the polarizing film obtained by rinsing and drying can be, for example, 1 to 50 μm.
(Transparent protective film)
The transparent protective film used in the production method of the present invention is preferably made of a material having excellent transparency, mechanical strength, thermal stability, moisture shielding properties, retardation value stability, and the like. Such a material for a transparent protective film is not particularly limited, but examples thereof include (meth) acrylic resins such as methyl methacrylate resins, chain polyolefin resins such as polypropylene resins, and cyclic olefin resins. Resin, polyvinyl chloride resin, cellulose resin, styrene resin, acrylonitrile / butadiene / styrene resin, acrylonitrile / styrene resin, polyvinyl acetate resin, polyvinylidene chloride resin, polyamide resin, polyacetal resin, Polycarbonate resins, modified polyphenylene ether resins, polybutylene terephthalate resins, polyethylene terephthalate resins, polysulfone resins, polyethersulfone resins, polyarylate resins, polyamideimide resins and polyimide resins Etc. and the like.
These resins can be used alone or in combination of two or more. These resins can also be used after any suitable polymer modification. Examples of the polymer modification include copolymerization, crosslinking, molecular terminal, stereoregularity control, and reaction between different polymers. Modifications such as mixing including the accompanying cases can be mentioned.
Among these, as the material for the transparent protective film, it is preferable to use a (meth) acrylic resin such as a methyl methacrylate resin, a chain polyolefin resin such as a polyethylene terephthalate resin or a polypropylene resin, or a cellulose resin. .
The methyl methacrylate resin is a polymer containing 50% by weight or more of methyl methacrylate units. The content of methyl methacrylate units is preferably 70% by weight or more, and may be 100% by weight. The polymer having a methyl methacrylate unit of 100% by weight is a methyl methacrylate homopolymer obtained by polymerizing methyl methacrylate alone.
This methyl methacrylate resin can be usually obtained by polymerization in the presence of a monofunctional monomer, a polyfunctional monomer, a radical polymerization initiator, and a chain transfer agent mainly composed of methyl methacrylate.
The monofunctional monomer that can be copolymerized with methyl methacrylate is not particularly limited. For example, ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, methacrylic acid 2 -Methacrylic acid esters other than methyl methacrylate such as ethylhexyl and 2-hydroxyethyl methacrylate; methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate And acrylic esters such as 2-hydroxyethyl acrylate; methyl 2- (hydroxymethyl) acrylate, methyl 3- (hydroxyethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate and 2 Hydroxyacrylic acid esters such as (hydroxymethyl) butyl acrylate; Unsaturated acids such as methacrylic acid and acrylic acid; Halogenated styrenes such as chlorostyrene and bromostyrene; Substituted styrenes such as vinyltoluene and α-methylstyrene Unsaturated nitriles such as acrylonitrile and methacrylonitrile; unsaturated acid anhydrides such as maleic anhydride and citraconic anhydride; and unsaturated imides such as phenylmaleimide and cyclohexylmaleimide. Such monomers may be used alone or in combination of two or more.
The polyfunctional monomer that can be copolymerized with methyl methacrylate is not particularly limited. For example, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate , Ethylene glycol such as tetraethylene glycol di (meth) acrylate, nonaethylene glycol di (meth) acrylate, and tetradecaethylene glycol (meth) acrylate, or both ester hydroxyl groups esterified with acrylic acid or methacrylic acid; Propylene glycol or its oligomers with both terminal hydroxyl groups esterified with acrylic acid or methacrylic acid; neopentyl glycol di (meth) acrylate, hexanediol di (meth) acrylate And a hydroxyl group of a dihydric alcohol such as butanediol di (meth) acrylate esterified with acrylic acid or methacrylic acid; bisphenol A, an alkylene oxide adduct of bisphenol A, or both terminal hydroxyl groups of these halogen-substituted products are acrylic Esterified with acid or methacrylic acid; polyhydric alcohol such as trimethylolpropane and pentaerythritol esterified with acrylic acid or methacrylic acid, and ring-opening addition of epoxy group of glycidyl acrylate or glycidyl methacrylate to these terminal hydroxyl groups Glycidyl acrylate or glycidyl succinic acid, adipic acid, terephthalic acid, phthalic acid, dibasic acids such as halogen substitution products thereof, and alkylene oxide adducts thereof. Those obtained by ring-opening addition of the epoxy group of Gilles methacrylate; aryl (meth) acrylate; and diaryl compounds such as divinylbenzene, and the like. Among these, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate and neopentyl glycol dimethacrylate are preferably used.
As the methyl methacrylate resin having such a composition, those modified by a reaction between functional groups copolymerized with the resin are also used. As the reaction, for example, demethanol condensation reaction in the polymer chain of a methyl ester group of methyl acrylate and a hydroxyl group of methyl 2- (hydroxymethyl) acrylate, or a carboxyl group of acrylic acid and 2- (hydroxymethyl) acrylic Examples thereof include a dehydration condensation reaction within a polymer chain of a hydroxyl group of methyl acid.
Such methyl methacrylate resin can be easily obtained as a commercial product. For example, Sumipex (manufactured by Sumitomo Chemical Co., Ltd.), Acripet (manufactured by Mitsubishi Rayon Co., Ltd.) under the trade name, respectively. , Delpet (manufactured by Asahi Kasei Co., Ltd.), Parapet (manufactured by Kuraray Co., Ltd.), and Acryviewer (manufactured by Nippon Shokubai Co., Ltd.).
The polyethylene terephthalate resin means a resin in which 80 mol% or more of repeating units are composed of ethylene terephthalate, and may contain other dicarboxylic acid components and diol components. Examples of other dicarboxylic acid components include, but are not limited to, isophthalic acid, p-β-oxyethoxybenzoic acid, 4,4′-dicarboxydiphenyl, 4,4′-dicarboxybenzophenone, bis (4-Carboxyphenyl) ethane, adipic acid, sebacic acid, 1,4-dicarboxycyclohexane and the like.
Other diol components are not particularly limited, but propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanediol, ethylene oxide adduct of bisphenol A, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc. Is mentioned.
These dicarboxylic acid components and diol components can be used in combination of two or more if necessary. Moreover, oxycarboxylic acids, such as p-oxybenzoic acid, can also be used together. Further, as other copolymerization component, a dicarboxylic acid component or a diol component containing a small amount of an amide bond, a urethane bond, an ether bond, a carbonate bond, or the like may be used.
Polyethylene terephthalate resin can be produced by direct polycondensation of terephthalic acid and ethylene glycol (and other dicarboxylic acids or other diols as required), dialkyl esters of terephthalic acid and ethylene glycol (and if necessary) A transesterification reaction with a dialkyl ester of another dicarboxylic acid or other diol), and a polycondensation, and an ethylene glycol ester of terephthalic acid (and other dicarboxylic acids as required) For example, a method of polycondensation of other diol ester) in the presence of a catalyst is employed. Furthermore, if necessary, solid-state polymerization can be performed to improve the molecular weight or reduce the low molecular weight components.
The polypropylene resin refers to a polymer obtained by polymerizing a chain olefin monomer in which 80% by weight or more of the repeating unit is a propylene monomer among the chain olefin resins. Among these, a propylene homopolymer is preferable. Also preferred is a copolymer comprising propylene as a main component and a comonomer copolymerizable therewith at a rate of 1 to 20% by weight, preferably 3 to 10% by weight.
When using a propylene copolymer, ethylene, 1-butene and 1-hexene are preferred as comonomers copolymerizable with propylene. Among these, ethylene copolymerized at a ratio of 3 to 10% by weight is preferable because of relatively excellent transparency. By setting the copolymerization ratio of ethylene to 1% by weight or more, an effect of increasing transparency appears. On the other hand, when the ratio exceeds 20% by weight, the melting point of the resin is lowered and the heat resistance required for the protective film may be impaired.
Among these, a propylene homopolymer having a component (CXS component) soluble in xylene at 20 ° C. of 1% by weight or less is more preferable, and a propylene homopolymer having a CXS component of 0.5% by weight or less is more preferable.
Cellulosic resins are those in which some or all of the hydrogen atoms in the hydroxyl groups of cellulose obtained from raw material cellulose such as cotton linter and wood pulp (hardwood pulp, conifer pulp) are acetyl groups, propionyl groups and / or butyryl groups. It refers to a substituted cellulose organic acid ester or cellulose mixed organic acid ester. Examples include cellulose acetates, propionic acid esters, butyric acid esters, and mixed esters thereof. Among these, a triacetyl cellulose film, a diacetyl cellulose film, a cellulose acetate propionate film, a cellulose acetate butyrate film, and the like are preferable.
As a method for making such a methyl methacrylate resin, a polyethylene terephthalate resin, a polypropylene resin, a cellulose resin, and the like as a transparent protective film to be bonded to a polarizing film, a method corresponding to the resin may be appropriately selected. There is no particular limitation. For example, a resin dissolved in a solvent is cast onto a metal band or drum, and a solvent casting method for obtaining a film by drying and removing the solvent, and the resin is heated and kneaded to a temperature higher than its melting temperature and extruded from a die, A melt extrusion method for obtaining a film by cooling is employed. In this melt extrusion method, a single layer film may be extruded or a multilayer film may be simultaneously extruded.
The film used as the transparent protective film thus obtained can be easily obtained as a commercial product. For example, as a methyl methacrylate-based resin film, the trade name is Sumipex (manufactured by Sumitomo Chemical Co., Ltd.). , Acrylite (Mitsubishi Rayon Co., Ltd.), Acryprene (Mitsubishi Rayon Co., Ltd.), Delagras (Asahi Kasei Co., Ltd.), Paragrass (Kuraray Co., Ltd.), Como Glass (Kuraray Co., Ltd.) (Manufactured by Nippon Shokubai Co., Ltd.).
Examples of the polyethylene terephthalate resin film include Novaclear (manufactured by Mitsubishi Chemical Corporation) and Teijin A-PET sheet (manufactured by Teijin Chemicals Ltd.).
In addition, for example, as polypropylene resin films, FILMAX CPP film (manufactured by FILMAX), Santox (manufactured by Sun Tox Co., Ltd.), Tosero (manufactured by Tosero Co., Ltd.), Toyobo Pyrene Film ( Toyobo Co., Ltd.), Treffan (Toray Film Processing Co., Ltd.), Nihon Polyace (Nihon Polyace Co., Ltd.), Dazai FC (Futamura Chemical Co., Ltd.), and the like.
Furthermore, for example, in the case of a cellulose-based resin film, Fujitac TD (manufactured by Fuji Film Co., Ltd.), Konica Minolta TAC film KC (manufactured by Konica Minolta Opto Co., Ltd.), and the like can be mentioned.
Antiglare property (haze) can be imparted to the transparent protective film used in the present invention. The method for imparting antiglare properties is not particularly limited. For example, a method of mixing inorganic fine particles or organic fine particles into the raw material resin to form a film, the multilayer extrusion described above, and the like. A method of forming a two-layer film from a resin in which fine particles are mixed and a resin in which fine particles are not mixed in the other, or a method of forming a three-layer film with the resin mixed with particles on the outside, and inorganic on one side of the film A method of coating a coating solution obtained by mixing fine particles or organic fine particles with a curable binder resin, curing the binder resin, and providing an antiglare layer is employed.
The inorganic fine particles for imparting antiglare properties are not particularly limited. For example, silica, colloidal silica, alumina, alumina sol, aluminosilicate, alumina-silica composite oxide, kaolin, talc, mica, carbonic acid. Examples thereof include calcium and calcium phosphate. Further, the organic fine particles are not particularly limited. For example, crosslinked polyacrylic acid particles, methyl methacrylate / styrene copolymer resin particles, crosslinked polystyrene particles, crosslinked polymethyl methacrylate particles, silicone resin particles, and polyimide are used. Particles and the like.
The haze value of the transparent protective film provided with the antiglare property thus obtained is preferably in the range of 6 to 45%. When the haze value of the transparent protective film is less than 6%, a sufficient antiglare effect may not appear. On the other hand, when the haze value of the transparent protective film exceeds 45%, the screen of the liquid crystal display device using this film may be browned, resulting in a decrease in image quality.
The haze value can be measured according to JIS K 7136, for example, using a haze / transmittance meter HM-150 (manufactured by Murakami Color Research Laboratory Co., Ltd.). In measuring the haze value, in order to prevent warping of the film, for example, a measurement sample in which the film surface is bonded to a glass substrate using an optically transparent adhesive so that the antiglare property-imparting surface is the surface. Is preferably used.
On the transparent protective film, functional layers such as a conductive layer, a hard coat layer and a low reflection layer can be further laminated. Moreover, the resin composition which has these functions can also be selected for binder resin which comprises a transparent protective film.
The transparent protective film is preferably subjected to saponification treatment, corona treatment, plasma treatment and the like prior to bonding with the polarizing film.
The thickness of the transparent protective film is not particularly limited, but is usually about 1 to 500 μm, preferably 20 to 300 μm, and more preferably 20 to 100 μm from the viewpoint of strength and handleability. When the thickness is within this range, the polarizing film is mechanically protected, and even when exposed to high temperature and high humidity, the polarizing film does not shrink and stable optical characteristics can be maintained.
(Adhesive for transparent protective film bonding)
The adhesive used for bonding the polarizing film and the transparent protective film is not particularly limited. For example, a polyvinyl alcohol resin, an epoxy resin, a urethane resin, a cyanoacrylate resin, and an acrylamide resin are used as the adhesive. An adhesive as a component can be mentioned. Among them, a water-based adhesive, that is, an adhesive component dissolved in water or dispersed in water is preferably used because the thickness of the adhesive layer can be further reduced. Examples of the water-based adhesive include those containing, for example, a polyvinyl alcohol resin, a water-soluble crosslinkable epoxy resin, a urethane resin, or the like as an adhesive component. As the polyvinyl alcohol-based resin, various known resins used as water-based adhesives can be used. As another preferable adhesive, an adhesive composed of a solventless resin composition in which a monomer or an oligomer is reactively cured by heating or irradiation with active energy rays to form an adhesive layer can be mentioned.
First, the water-based adhesive will be described. Examples of water-soluble crosslinkable epoxy resins include polyamide epoxies obtained by reacting epichlorohydrin with polyamide polyamines obtained by reaction of polyalkylene polyamines such as diethylenetriamine and triethylenetetramine with dicarboxylic acids such as adipic acid. Resins can be mentioned. Examples of commercially available products of such polyamide epoxy resins include Sumire Resin 650 (manufactured by Sumika Chemtex Co., Ltd.), Sumire Resin 675 (manufactured by Sumika Chemtex Co., Ltd.), and the like.
In order to improve coatability and adhesiveness, it is preferable to further mix other water-soluble resin such as polyvinyl alcohol resin in the adhesive. Polyvinyl alcohol-based resins include partially saponified polyvinyl alcohol and fully saponified polyvinyl alcohol, as well as modified carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, methylol group-modified polyvinyl alcohol, and amino group-modified polyvinyl alcohol. Polyvinyl alcohol resin may be used. Among them, a saponified product of a copolymer of vinyl acetate and unsaturated carboxylic acid or a salt thereof, that is, carboxyl group-modified polyvinyl alcohol is preferably used. Here, the “carboxyl group” is a concept including —COOH and a salt thereof.
Examples of suitable carboxyl group-modified polyvinyl alcohol commercially available include Kuraray Poval KL-506 (manufactured by Kuraray Co., Ltd.), Kuraray Poval KL-318 (manufactured by Kuraray Co., Ltd.), and Kuraray Poval KL-118 (( Kuraray Co., Ltd.), Gohsenal T-330 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), Gohsenal T-350 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), DR-0415 (manufactured by Denki Kagaku Kogyo Co., Ltd.), AF -17 (manufactured by Nippon Vinegar Poval Co., Ltd.), AT-17 (manufactured by Nippon Vinegar Pobart Co., Ltd.), AP-17 (manufactured by Nippon Vinegar Poval Co., Ltd.) and the like.
The adhesive can be prepared as an adhesive solution by dissolving an epoxy resin and other water-soluble resin such as a polyvinyl alcohol-based resin added as necessary in water. In this case, the content of the water-soluble crosslinkable epoxy resin is preferably about 0.2 to 2 parts by weight with respect to 100 parts by weight of water. When the polyvinyl alcohol-based resin is blended, the blending amount is preferably about 1 to 10 parts by weight, and more preferably about 1 to 5 parts by weight with respect to 100 parts by weight of water.
On the other hand, examples of urethane resins that can be suitably used for water-based adhesives include ionomer-type urethane resins, particularly polyester-type ionomer-type urethane resins. Here, the ionomer type is obtained by introducing a small amount of an ionic component (hydrophilic component) into the skeleton constituting the urethane resin. The polyester ionomer type urethane resin is a urethane resin having a polyester skeleton, and a small amount of an ionic component (hydrophilic component) is introduced into the skeleton. Such an ionomer type urethane resin is suitable as a water-based adhesive because it is emulsified directly in water without using an emulsifier and becomes an emulsion. Examples of commercially available polyester ionomer type urethane resins include Hydran AP-20 (Dainippon Ink Chemical Co., Ltd.), Hydran APX-101H (Dainippon Ink Chemical Co., Ltd.), etc. Is also available in the form of an emulsion.
When an ionomer-type urethane resin is used as an adhesive component, it is preferable to further blend an isocyanate-based crosslinking agent. The isocyanate-based crosslinking agent is a compound having at least two isocyanato groups (—NCO) in the molecule. For example, 2,4-tolylene diisocyanate, phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 1,6-hexa In addition to polyisocyanate monomers such as methylene diisocyanate and isophorone diisocyanate, adducts in which a plurality of these molecules are added to a polyhydric alcohol such as trimethylolpropane, and three molecules of diisocyanate are isocyanurates at each end isocyanato group And polyisocyanate modified products such as burettes formed by hydration and decarboxylation of trifunctional isocyanurate having a ring formed and three diisocyanate molecules at the respective one-end isocyanate groups. As a commercially available isocyanate type crosslinking agent which can be used suitably, Hydran Assist C-1 (made by Dainippon Ink & Chemicals, Inc.) etc. are mentioned, for example.
In an aqueous adhesive containing an ionomer type urethane resin, from the viewpoint of viscosity and adhesiveness, the concentration of the urethane resin is preferably dissolved or dispersed in water so as to be about 10 to 70% by weight. It is more preferably up to 50% by weight. Further, when the isocyanate crosslinking agent is blended, the blending amount is appropriately selected so that the isocyanate crosslinking agent is about 5 to 100 parts by weight with respect to 100 parts by weight of the urethane resin.
In the case of using the aqueous adhesive thus formed, the adhesive is applied to the adhesive surface of the transparent protective film or the polarizing film, and the laminated body of the polarizing film and the transparent protective film is obtained by bonding and drying both. be able to.
Next, an adhesive made of a solventless resin composition containing an epoxy resin that is cured by irradiation with active energy rays or heating will be described.
The adhesive used in the production method of the present invention is a curable composition that contains a curable compound that is polymerized by heating or irradiation with active energy rays and a polymerization initiator and does not contain a significant amount of solvent. This curable compound is preferably one that is cured by cationic polymerization from the viewpoint of reactivity, and particularly preferably contains an epoxy compound (epoxy resin).
As this epoxy compound, those having no aromatic ring in the molecule are suitably used from the viewpoint of weather resistance, refractive index and the like. An adhesive using an epoxy compound that does not contain an aromatic ring in the molecule is described in, for example, Japanese Patent Application Laid-Open No. 2004-245925. Examples of such epoxy compounds that do not contain an aromatic ring include hydrides of aromatic epoxy compounds, alicyclic epoxy compounds, and aliphatic epoxy compounds.
A hydride of an aromatic epoxy compound is obtained by selectively hydrogenating an aromatic epoxy compound to an aromatic ring under pressure in the presence of a catalyst. Examples of the aromatic epoxy compound include bisphenol type epoxy compounds such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and diglycidyl ether of bisphenol S; phenol novolac epoxy resin, cresol novolac epoxy resin, And a novolak type epoxy resin such as hydroxybenzaldehyde phenol novolac epoxy resin; a glycidyl ether of tetrahydroxydiphenylmethane, a glycidyl ether of tetrahydroxybenzophenone, and a polyfunctional type epoxy compound such as epoxidized polyvinylphenol. Of these, hydrogenated diglycidyl ether of bisphenol A is preferred.
An alicyclic epoxy compound is a compound having at least one epoxy group bonded to an alicyclic ring in the molecule, as shown in the following formula.

(In the formula, m represents an integer of 2 to 5.)
(CH in this formula ₂ ) _m A compound in which a group in which one or more hydrogen atoms are removed is bonded to another chemical structure can be an alicyclic epoxy compound. Further, the hydrogen forming the alicyclic ring may be appropriately substituted with a linear alkyl group such as a methyl group or an ethyl group. Among them, it is preferable to use a compound having an epoxycyclopentane ring (m = 3 in the above formula) or an epoxycyclohexane ring (m = 4 in the above formula). Specific examples of the alicyclic epoxy compound include the following.
3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, 3,4-epoxy-6-methylcyclohexylmethyl 3,4-epoxy-6-methylcyclohexanecarboxylate, ethylenebis (3,4-epoxycyclohexanecarboxy Rate), bis (3,4-epoxycyclohexylmethyl) adipate, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, diethylene glycol bis (3,4-epoxycyclohexylmethyl ether), ethylene glycol bis (3,4 4-epoxycyclohexyl methyl ether), 2,3,14,15-diepoxy-7,11,18,21-tetraoxatrispiro- [5.2.2.5.2.2] henicosane (also 3, 4-epoki Cycyclohexanespiro-2 ′, 6′-dioxanespiro-3 ″, 5 ″ -dioxanespiro-3 ″ ′, 4 ′ ″-epoxycyclohexane compound),
4- (3,4-epoxycyclohexyl) -2,6-dioxa-8,9-epoxyspiro [5.5] undecane, 4-vinylcyclohexene dioxide, bis-2,3-epoxycyclopentyl ether, and dicyclo Pentadiene dioxide etc.
The aliphatic epoxy compound is a polyglycidyl ether of an aliphatic polyhydric alcohol or an alkylene oxide adduct thereof. For example, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl Polyglycidyl ethers of polyether polyols obtained by adding one or more alkylene oxides (ethylene oxide or polypropylene oxide) to aliphatic polyhydric alcohols such as ether, ethylene glycol, polypropylene glycol, and glycerin, etc. Is mentioned.
The epoxy compounds illustrated here may be used alone or in combination with a plurality of epoxy compounds.
The epoxy equivalent of such an epoxy compound is usually 30 to 3000 g / eq, preferably 50 to 1500 g / eq. When the epoxy equivalent is less than 30 g / eq, the flexibility of the cured protective film may be reduced or the adhesive strength may be reduced. On the other hand, when it exceeds 3000 g / eq, the compatibility with other components may decrease.
In the curable composition, a cationic polymerization initiator is blended in order to cure the epoxy compound by cationic polymerization. The cationic polymerization initiator generates a cationic species or a Lewis acid by irradiation with active energy rays such as visible light, ultraviolet rays, X-rays, and electron beams, or by heating, and starts an epoxy group polymerization reaction. Regardless of the type of cationic polymerization initiator, it is preferable from the viewpoint of workability that latency is imparted.
Hereinafter, a photocationic polymerization initiator that generates a cationic species or a Lewis acid by irradiation with active energy rays will be described. Use of a cationic photopolymerization initiator enables curing at room temperature, reduces the need to consider the internal stress due to heat resistance or thermal expansion of the polarizing film, and allows the transparent protective film and the polarizing film to adhere well. it can. Moreover, since a photocationic polymerization initiator acts catalytically by light, it is excellent in storage stability and workability even when mixed with an epoxy compound. Examples of the compound that generates a cation species or a Lewis acid upon irradiation with active energy rays include onium salts such as aromatic diazonium salts, aromatic iodonium salts and aromatic sulfonium salts, and iron-allene complexes. Among these, aromatic sulfonium salts are particularly preferably used since they have ultraviolet absorption characteristics even in a wavelength region of 300 nm or more, and can provide a cured product having excellent curability and good mechanical strength and adhesive strength.
Such a cationic photopolymerization initiator can be easily obtained as a commercial product. For example, Kayrad PCI-220 (manufactured by Nippon Kayaku Co., Ltd.), Kayrad PCI-620 (manufactured by Nippon Kayaku Co., Ltd.) under the trade names, respectively. ), UVI-6990 (manufactured by Union Carbide), Adekaoptomer SP-150 (manufactured by ADEKA), Adekaoptomer SP-170 (manufactured by ADEKA), CI-5102 (manufactured by Nippon Soda Co., Ltd.) ), CIT-1370 (manufactured by Nippon Soda Co., Ltd.), CIT-1682 (manufactured by Nippon Soda Co., Ltd.), CIP-1866S (manufactured by Nippon Soda Co., Ltd.), CIP-2048S (manufactured by Nippon Soda Co., Ltd.), CIP-2064S (Nippon Soda Co., Ltd.), DPI-101 (Midori Chemical Co., Ltd.), DPI-102 (Midori Chemical Co., Ltd.), DPI-103 (Midori Chemical Co., Ltd.) ), DPI-105 (manufactured by Midori Chemical Co., Ltd.), MPI-103 (manufactured by Midori Chemical Co., Ltd.), MPI-105 (manufactured by Midori Chemical Co., Ltd.), BBI-101 (manufactured by Midori Chemical Co., Ltd.) ), BBI-102 (manufactured by Midori Chemical Co., Ltd.), BBI-103 (manufactured by Midori Chemical Co., Ltd.), BBI-105 (manufactured by Midori Chemical Co., Ltd.), TPS-101 (manufactured by Midori Chemical Co., Ltd.), TPS-102 (manufactured by Midori Chemical Co., Ltd.), TPS-103 (manufactured by Midori Chemical Co., Ltd.), TPS-105 (manufactured by Midori Chemical Co., Ltd.), MDS-103 (manufactured by Midori Chemical Co., Ltd.), MDS- 105 (manufactured by Midori Chemical Co., Ltd.), DTS-102 (manufactured by Midori Chemical Co., Ltd.), DTS-103 (manufactured by Midori Chemical Co., Ltd.), PI-2074 (manufactured by Rhodia) and the like.
The amount of the cationic photopolymerization initiator is usually 0.5 to 20 parts by weight, preferably 1 to 15 parts by weight, based on 100 parts by weight of the epoxy compound.
A photosensitizer can be used in combination with the curable composition as necessary. By using a photosensitizer, the reactivity is improved and the mechanical strength and adhesive strength of the cured product can be improved. Examples of the photosensitizer include carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo and diazo compounds, halogen compounds, and photoreductive dyes. When the photosensitizer is blended, the blending amount is usually about 0.1 to 20 parts by weight with 100 parts by weight of the photocationically polymerizable epoxy resin composition.
Next, the thermal cationic polymerization initiator will be described. Examples of the compound that generates a cationic species or a Lewis acid by heating include benzylsulfonium salt, thiophenium salt, thiolanium salt, benzylammonium, pyridinium salt, hydrazinium salt, carboxylic acid ester, sulfonic acid ester, and amine imide. Commercially available products of these thermal cationic polymerization initiators can also be easily obtained. For example, they are trade names such as Adeka Opton CP77 (manufactured by ADEKA), Adeka Opton CP66 (manufactured by ADEKA), CI- 2639 (manufactured by Nippon Soda Co., Ltd.), CI-2624 (manufactured by Nippon Soda Co., Ltd.), Sun-Aid SI-60L (manufactured by Sanshin Chemical Industry Co., Ltd.), Sun-Aid SI-80L (manufactured by Sanshin Chemical Industry Co., Ltd.) ), Sun Aid SI-100L (manufactured by Sanshin Chemical Industry Co., Ltd.) and the like.
It is also a useful technique to use the above cationic photopolymerization and thermal cationic polymerization together.
The epoxy-based adhesive may further contain a compound that promotes cationic polymerization such as oxetanes and polyols.
The adhesive comprising the curable composition thus obtained is applied to the adhesive surface of the transparent protective film or the polarizing film, and after both are laminated, the adhesive is cured to laminate the polarizing film and the transparent protective film. You can get a body. There is no particular limitation on the method of applying this adhesive to the transparent protective film or polarizing film. For example, various coating methods such as doctor blade, wire bar, die coater, comma coater, and gravure coater are adopted. . The thickness of the adhesive layer is usually 1 μm or more and 50 μm or less, preferably 20 μm or less, and more preferably 10 μm or less.
When the adhesive is cured by irradiation with active energy rays, the light source used is not particularly limited, but has a light emission distribution at a wavelength of 400 nm or less, such as a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, Examples include ultra-high pressure mercury lamps, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps. The light irradiation intensity to the adhesive composition is determined by the curability of the composition and is not particularly limited. For example, the light irradiation intensity in the wavelength region effective for activating the photocationic polymerization initiator is used. Irradiation intensity is 0.1-100mW / cm ² It is preferable that The light irradiation intensity to the adhesive composition is 0.1 mW / cm ² If it is less than 100 mW / cm, the reaction time becomes too long. ² Exceeding may cause yellowing of the curable epoxy resin composition or deterioration of the polarizing film due to heat radiated from the lamp and heat generation during polymerization of the curable epoxy resin composition. Similarly, the light irradiation time for the adhesive composition is determined by the curability of the composition, and is not particularly limited. For example, it is expressed as a product of irradiation intensity and irradiation time. 10 to 5000mJ / cm ² It is preferable to set so that. Integrated light quantity to curable epoxy resin composition is 10mJ / cm ² If it is less than 1, the generation of the active species derived from the cationic photopolymerization initiator is not sufficient, and the curing of the adhesive may be insufficient. Also, the integrated light quantity is 5000mJ / cm ² If it exceeds 1, irradiation time becomes very long, which is disadvantageous for productivity improvement.
When the adhesive is cured by heat, the adhesive can be heated by a generally known method, and the conditions are not particularly limited, but usually the heat blended in the curable epoxy resin composition. Heating is performed at a temperature higher than the temperature at which the cationic polymerization initiator generates cationic species and Lewis acid, and the temperature is, for example, about 50 to 200 ° C.
Even if it is cured under any condition of irradiation with active energy rays or heating, it should be cured as long as the functions such as polarization degree, transmittance, hue, transparency of the transparent protective film of the polarizing plate with a single-sided protective film do not deteriorate. Is preferred. The thickness of the cured layer formed by curing the adhesive composition is usually 50 μm or less, preferably 20 μm or less, and more preferably 10 μm or less.
(Peelable film)
As the peelable film having adhesiveness used in the production method of the present invention, a film that has been treated with a low molecular weight pressure-sensitive adhesive so as to be easily peeled can be used. For example, polyesters such as polyethylene terephthalate and polyethylene naphthalate Resins; Cyclic olefin resins; Chain olefin resins such as polyethylene, polypropylene, and propylene / ethylene copolymers can be used. Among them, a polyethylene terephthalate film, a polypropylene film, or a polyethylene film is preferably used from the viewpoint that the adhesiveness can be adjusted as appropriate and a commercially available product is easily available.
The peelable film has self-adhesiveness and can be directly bonded to the surface of the polarizing film opposite to the surface to which the transparent protective film is bonded.
Thus, a polarizing plate with a single-sided transparent protective film in which a transparent protective film is bonded to one side of a polarizing film by an adhesive and a peelable film having adhesiveness is bonded to the opposite side is once a winding device. Is wound around a core such as a vinyl chloride tube. In addition, either the process of bonding a transparent protective film to a polarizing film and the process of bonding a peelable film to a polarizing film may be performed first, and may be performed simultaneously.
(Retardation film)
The retardation film used in the production method of the present invention is made of an olefin resin, and n _x > N _z > N _y A so-called biaxial retardation film satisfying the above relationship is preferable. The olefin resin is mainly derived from a chain aliphatic olefin such as ethylene or propylene, or an alicyclic olefin such as norbornene or a substituted product thereof (hereinafter also collectively referred to as a norbornene monomer). It is a resin composed of structural units. The olefin resin may be a copolymer using two or more kinds of monomers.
Among them, a resin mainly containing a structural unit mainly derived from an alicyclic olefin is preferable, and a cyclic olefin resin in which a cyclic structure derived from the alicyclic olefin remains in the main chain after polymerization is more preferable. Preferably used. Typical examples of the alicyclic olefin constituting the cyclic olefin resin include a norbornene monomer. Norbornene is a compound in which one carbon-carbon bond of norbornane is a double bond, and according to IUPAC nomenclature, it is named bicyclo [2,2,1] hept-2-ene. is there. Examples of substituted norbornene include 3-substituted, 4-substituted, 4,5-disubstituted, etc., with the norbornene double bond located at the 1,2-position. Examples also include cyclopentadiene and dimethanooctahydronaphthalene. Such a resin mainly composed of a structural unit derived from a norbornene-based monomer is generally called a norbornene-based resin.
The norbornene-based resin containing a structural unit derived from a norbornene-based monomer may or may not have a norbornane ring in the structural unit. Examples of the norbornene-based monomer that forms a norbornene-based resin having no norbornane ring as a structural unit include, for example, those that become a five-membered ring by ring opening, typically norbornene, dicyclopentadiene, 1- or 4-methyl. Examples include norbornene and 4-phenylnorbornene. When the norbornene resin is a copolymer, the arrangement state of the molecules is not particularly limited, and may be a random copolymer, a block copolymer, or a graft copolymer. May be.
Examples of the cyclic olefin-based resin include, for example, a ring-opening polymer of a norbornene-based monomer, a ring-opening copolymer of a norbornene-based monomer and another monomer, a modified polymer obtained by adding maleic acid, cyclopentadiene, or the like to them. Further, a polymer or copolymer obtained by hydrogenation of these; an addition polymer of a norbornene monomer, an addition copolymer of a norbornene monomer and another monomer, and the like. Examples of other monomers in the copolymer include α-olefins, cycloalkenes, and non-conjugated dienes. Moreover, the cyclic olefin resin may be a copolymer using one or more of norbornene monomers and other alicyclic olefins.
Among these, as the cyclic olefin-based resin, a resin obtained by hydrogenating a ring-opening polymer or a ring-opening copolymer using a norbornene-based monomer is preferably used. A film-like product obtained by subjecting such a norbornene-based resin to a stretching treatment, and a shrinkable film having a predetermined shrinkage rate are bonded to each other and heat-shrinked, thereby providing high uniformity and a large retardation value. A phase difference film can be obtained. Commercially available hydrogenated products of ring-opening polymers or ring-opening copolymers using such norbornene-based monomers are all trade names, Zeonex (manufactured by Nippon Zeon Co., Ltd.), Zeonore (Japan Zeon ( And Arton (manufactured by JSR Corporation). As these norbornene-based resin films and stretched films, for example, Zeonore Film (manufactured by Optes Co., Ltd.), Arton Film (manufactured by JSR Co., Ltd.), Essina (manufactured by Sekisui Chemical Co., Ltd.), etc. are sold. ing.
In addition, as the retardation film used in the production method of the present invention, a film made of a mixed resin containing two or more kinds of olefin resins or a film made of a mixed resin of an olefin resin and another thermoplastic resin is used. You can also. For example, as an example of a mixed resin containing two or more types of olefinic resins, there can be mentioned a mixture of a cyclic olefinic resin and an acyclic aliphatic olefinic resin as described above. When a mixed resin of an olefin resin and another thermoplastic resin is used, another thermoplastic resin is appropriately selected depending on the purpose. For example, polyvinyl chloride resin, cellulose resin, polystyrene resin, acrylonitrile / butadiene / styrene copolymer resin, acrylonitrile / styrene copolymer resin, (meth) acrylic resin, polyvinyl acetate resin, polyvinylidene chloride resin , Polyamide resin, polyacetal resin, polycarbonate resin, modified polyphenylene ether resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyphenylene sulfide resin, polysulfone resin, polyethersulfone resin, polyether ether ketone Examples thereof include resins, polyarylate resins, liquid crystalline resins, polyamideimide resins, polyimide resins, and polytetrafluoroethylene resins. These thermoplastic resins can be used alone or in combination of two or more. The thermoplastic resin may be used after any appropriate polymer modification. Examples of the polymer modification include copolymerization, crosslinking, molecular terminal modification, and stereoregularity imparting.
When a mixed resin of an olefin resin and another thermoplastic resin is used, the content of the other thermoplastic resin is usually 50% by weight or less and preferably 40% by weight or less based on the entire resin. By setting the content of other thermoplastic resins within this range, the retardation value film has a small absolute value of the photoelastic coefficient, exhibits good wavelength dispersion characteristics, and is excellent in durability, mechanical strength, and transparency. Can be obtained.
Such an olefin resin can be formed into a film by a casting method or a melt extrusion method from a commonly used solution. When forming a film from two or more kinds of mixed resins, the film forming method is not particularly limited. For example, by casting using a uniform solution obtained by stirring and mixing resin components with a solvent at a predetermined ratio. A method for producing a film, a method for melt-mixing resin components at a predetermined ratio, and producing a film by a melt extrusion method are employed.
The film made of the olefin-based resin may contain other components such as a residual solvent, a stabilizer, a plasticizer, an anti-aging agent, an antistatic agent, and an ultraviolet absorber as long as the object of the present invention is not impaired. You may contain. Further, a leveling agent can be contained in order to reduce the surface roughness.
The retardation film used in the production method of the present invention has an in-plane slow axis direction, an in-plane fast axis direction, and a thickness direction refractive index of n. _x , N _y And n _z When the thickness is d (nm), those satisfying the formulas (1) and (2) with respect to light having a wavelength of 590 nm are preferable.
100 nm ≦ (n _x -N _y ) × d ≦ 300 nm (1)
0.1 ≦ (n _x -N _z ) / (N _x -N _y ) ≦ 0.7 (2)
By using such a retardation film having specific refractive index anisotropy, the display characteristics of the liquid crystal cell can be suitably compensated over a wide angle when the composite polarizing plate is applied to a liquid crystal display device.
The thickness of the retardation film can be in the range of about 20 to 500 μm, preferably 20 to 300 μm. If the thickness is within this range, sufficient self-supporting property of the film can be obtained, and a wide range of retardation can be obtained.
When this retardation film is used as a λ / 2 plate, the in-plane retardation value for the light having a wavelength of 590 nm is preferably in the range of about 200 to 300 nm, and more preferably in the range of 240 to 300 nm. . By setting the in-plane retardation value for light with a wavelength of 590 nm to about ½ of the measurement wavelength, the display characteristics of the liquid crystal display device can be further improved. When the retardation film is used as a λ / 2 plate, the thickness is preferably in the range of 80 to 160 μm in order to sufficiently align in the thickness direction. More preferably, it is in the range of 85 to 145 μm. In addition, this retardation film may be used as a λ / 4 plate.
N of this retardation film _Z Coefficient ((n _x -N _z ) / (N _x -N _y )) Is preferably from 0.1 to 0.7, more preferably from 0.3 to 0.6. N of retardation film _Z When the coefficient is around 0.5, it is possible to achieve a characteristic in which the phase difference value is almost constant regardless of the angle, and the display characteristics of the liquid crystal display device can be further improved.
The width of the retardation film is preferably 10% or more smaller than that of the polarizing plate because the effect of improving productivity stands out. Furthermore, if the width is in the range of 40 to 50% of the polarizing plate, the polarizing plate with a single-sided transparent protective film is cut (slit) to half the width, and both of them are bonded to the retardation film. It is more preferable because it can be used for
[First manufacturing method of composite polarizing plate]
[1] Step (A)
In the first production method of the composite polarizing plate of the present invention, first, a transparent protective film is bonded to one side of the polarizing film, and a peelable film having adhesiveness is bonded to the opposite surface, thereby providing single-sided transparent protection. A polarizing plate with a film is produced (step (A)).
[2] Process (B)
Next, the first method for producing the composite polarizing plate of the present invention is to cut the polarizing plate with a single-sided transparent protective film produced as described above along the longitudinal direction according to the width of the retardation film (slit (Step (B)). The width after cutting of the polarizing plate with a single-sided transparent protective film is appropriately set according to the width of the retardation film. For example, at least one piece of the polarizing plate with a single-sided transparent protective film after cutting is made of the retardation film. The width is preferably the same as the width.
The method of cutting the polarizing plate with a single-sided transparent protective film is not particularly limited, but usually the rolled-up polarizing plate with a single-sided transparent protective film is fed simultaneously to a slitter (long-direction cutting machine). Then, a method of rewinding the cut pieces is adopted.
[3] Process (C)
In the first production method of the composite polarizing plate of the present invention, next, the peelable film of the polarizing plate with the single-sided transparent protective film cut in the step (B) is removed, and the polarizing film surface and the phase difference are removed. The film is bonded using an epoxy resin composition containing an epoxy resin that is cured by irradiation with active energy rays or heating (step (C)).
(Epoxy resin composition for retardation film bonding)
The epoxy resin composition containing an epoxy resin that is cured by irradiation with active energy rays or heating, which is used for bonding the polarizing film and the retardation film, is preferably solventless. As this epoxy resin composition, the thing similar to what was illustrated as an adhesive agent used for adhesion | attachment with a polarizing film and a transparent protective film is mentioned.
The method for adhering the polarizing plate with a single-sided protective film and the retardation film with this adhesive is not particularly limited, for example, a doctor blade, a wire bar, a die coater, a comma coater, a gravure coater, etc. Various coating methods are employed. Moreover, after dripping the said adhesive composition between a polarizing film and a protective film, the method of pressurizing a polarizing film and a protective film with a roll etc. and spreading it uniformly can also be utilized. Here, metal, rubber, or the like can be used as the material of the roll, and these rolls may be made of the same material or different materials. The thickness of the adhesive layer is usually 50 μm or less, preferably 20 μm or less, and more preferably 10 μm or less.
When the adhesive is cured by irradiation with active energy rays, the light source used is not particularly limited, but has a light emission distribution at a wavelength of 400 nm or less, such as a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, Examples include ultra-high pressure mercury lamps, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps. The light irradiation intensity to the adhesive composition is determined by the curability of the composition and is not particularly limited. For example, the light irradiation intensity of the adhesive composition has a wavelength region effective for activation of the photocationic polymerization initiator. Irradiation intensity is 0.1-100mW / cm ² It is preferable that The light irradiation intensity to the adhesive composition is 0.1 mW / cm ² If it is less than 100 mW / cm, the reaction time becomes too long. ² Exceeding may cause yellowing of the curable epoxy resin composition or deterioration of the polarizing film due to heat radiated from the lamp and heat generation during polymerization of the curable epoxy resin composition. Similarly, the light irradiation time for the adhesive composition is determined by the curability of the composition, and is not particularly limited. For example, it is expressed as a product of irradiation intensity and irradiation time. 10 to 5000mJ / cm ² It is preferable to set so that. Integrated light quantity to curable epoxy resin composition is 10mJ / cm ² If it is less than 1, the generation of the active species derived from the cationic photopolymerization initiator is not sufficient, and the curing of the adhesive may be insufficient. Also, the integrated light quantity is 5000mJ / cm ² If it exceeds 1, irradiation time becomes very long, which is disadvantageous for productivity improvement.
When the adhesive is cured by heat, it can be heated by a generally known method, and the conditions thereof are not particularly limited, but usually the heat blended in the curable epoxy resin composition. Heating is performed at a temperature higher than the temperature at which the cationic polymerization initiator generates cationic species and Lewis acid, and the temperature is, for example, about 50 to 200 ° C.
Even if it is cured under either conditions of irradiation with active energy rays or heating, the polarization degree, transmittance, hue, transparency of the transparent protective film, and retardation characteristics of the retardation film are combined. It is preferable to cure in the range where the various functions of the polarizing plate do not deteriorate. The thickness of the cured layer formed by curing the adhesive composition is usually 50 μm or less, preferably 20 μm or less, and more preferably 10 μm or less.
In the 1st manufacturing method of the composite polarizing plate of this invention, an adhesive layer may be further provided in the outer side of the retardation film bonded by the composite polarizing plate. The pressure-sensitive adhesive layer can be suitably used for bonding with other members such as a liquid crystal cell. The composite polarizing plate thus formed is usually arranged so that the retardation film side faces the liquid crystal cell when being bonded to the liquid crystal cell.
[Second production method of composite polarizing plate]
The second manufacturing method of the composite polarizing plate of the present invention includes the following steps (A), (B), (C), (D) and (E).
・ Process (A)
A process for producing a polarizing plate with a single-sided transparent protective film by laminating a transparent protective film on one side of the polarizing film and laminating an adhesive peelable film on the opposite side.
・ Process (B)
The process of cutting the polarizing plate with a single-sided transparent protective film along the longitudinal direction according to the width of the retardation film
・ Process (C)
The process of removing the peelable film from the polarizing film surface
・ Process (D)
The process of laminating | stacking the adhesive layer which shows the storage elastic modulus of 0.1 Mpa or more in 80 degreeC on the polarizing film surface of the polarizing plate with the said single-sided transparent protective film which passed through the said process (C) of the said retardation film.
・ Process (E)
The process of bonding the said retardation film to the polarizing film surface from which the said peelable film was removed through the said adhesive layer.
Such a second method for producing a composite polarizing plate of the present invention roughly includes three embodiments (first embodiment, second embodiment and third embodiment). First, each embodiment included in the second production method of the present invention will be described.
<First aspect>
The 1st aspect in the 2nd manufacturing method of this invention contains the process (A), the process (B), the process (C), the process (D), and the process (E) which were mentioned above in this order, and the process (D ), The pressure-sensitive adhesive layer is laminated on the polarizing film surface of the polarizing plate with the single-side transparent protective film that has undergone the step (C).
In the 1st aspect in the 2nd manufacturing method of this invention, first, a transparent protective film is bonded on the single side | surface of a polarizing film, the peelable film which has adhesiveness is bonded on the surface of an other side, and single-sided transparent protection A polarizing plate with a film is produced (step (A)).
In the first aspect of the second production method of the present invention, next, the polarizing plate with a single-sided transparent protective film produced as described above is cut along the longitudinal direction according to the width of the retardation film ( Slit) (step (B)). The width after cutting of the polarizing plate with a transparent protective film is appropriately set according to the width of the retardation film. For example, at least one fragment of the polarizing plate with a single-side transparent protective film after cutting is the width of the retardation film. The width is preferably the same.
The method of cutting the polarizing plate with a single-sided transparent protective film is not particularly limited, but usually the rolled-up polarizing plate with a single-sided transparent protective film is fed simultaneously to a slitter (long-direction cutting machine). Then, a method of rewinding the cut pieces is adopted. Moreover, the method of laminating | stacking the polarizing plate cut according to the width | variety of retardation film with a retardation film through an adhesive on the spot is also employ | adopted.
In the first aspect of the second production method of the present invention, next, the peelable film is removed from the polarizing film surface (step (C)). Furthermore, in the 1st aspect in the 2nd manufacturing method of this invention, on the polarizing film surface (surface with which the peelable film was bonded) of the said polarizing plate with a single-sided transparent protective film which passed the said process (C), A pressure-sensitive adhesive layer showing a storage elastic modulus of 0.1 MPa or higher at 80 ° C. is laminated (step (D)).
(Adhesive)
The pressure-sensitive adhesive used for forming the pressure-sensitive adhesive layer has a storage elastic modulus at 80 ° C. of 0.1 MPa or more, preferably 0.15 to 10 MPa. When the storage elastic modulus at 80 ° C. is less than 0.1 MPa, there is a problem that bubbles and peeling occur because the dimensional change of the polarizing film that occurs when the high temperature environment and the low temperature environment are repeated cannot be followed. Because. Further, the storage elastic modulus at a temperature of 23 ° C. of this pressure-sensitive adhesive is preferably 0.1 MPa or more, and more preferably 0.2 to 10 MPa. In addition, since the storage elastic modulus generally tends to be lower as the temperature is higher, if the storage elastic modulus of the material measured at 80 ° C. is 0.1 MPa or more, usually the same material measured at 23 ° C. A storage elastic modulus shows the value beyond it.
Here, the storage elastic modulus (dynamic elastic modulus) is a commonly used term for viscoelasticity measurement, and gives a strain or stress that changes (vibrates) over time to a sample. This is a value determined by a method (dynamic viscoelasticity measurement) for measuring the mechanical properties of a sample by measuring the stress or strain generated by. Specifically, when the stress (strain) generated by the sinusoidal strain (stress) applied to the sample is divided into a component having the same phase as the strain (stress) and a component having a phase shifted by 90 degrees, The elastic modulus calculated from the stress (strain) component in phase with the stress. The storage elastic modulus can be measured using a commercially available viscoelasticity measuring device, for example, a dynamic viscoelasticity measuring device (Dynamic Analyzer RDA II: manufactured by REOMETRIC) as shown in the examples described later. For the temperature control of the viscoelasticity measuring apparatus, various known temperature control devices such as a circulating thermostat, an electric heater, a Peltier element, and the like are used, and thereby the temperature at the time of measurement can be set.
The pressure-sensitive adhesive used in a normal image display device or an optical film applied thereto has a storage elastic modulus of about 0.1 MPa at most, but the pressure-sensitive adhesive used in the production method of the present invention is as described above. The storage elastic modulus is high. By using such a high storage elastic modulus, that is, a hard adhesive, it is possible to compensate for the lack of cohesive force when placed in a high temperature environment or when a high temperature environment and a low temperature environment are repeated. The dimensional change accompanying the shrinkage | contraction of the polarizing film sometimes generated can be suppressed. By this action, the composite polarizing plate of the present invention has good durability.
The specific high-elasticity adhesive used in the production method of the present invention can be composed of a composition mainly containing, for example, an acrylic polymer, a silicone polymer, polyester, polyurethane, and polyether. Above all, like acrylic polymer, it has excellent optical transparency, moderate wettability and cohesion, excellent adhesion to the substrate, weather resistance, heat resistance, etc. It is preferable to select and use one that does not cause peeling problems such as floating and peeling under humidifying conditions. In the acrylic polymer, a functional group comprising an alkyl ester of acrylic acid having an alkyl group having 20 or less carbon atoms such as a methyl group, an ethyl group and a butyl group, and (meth) acrylic acid or hydroxyethyl (meth) acrylate. An acrylic copolymer having a weight average molecular weight of 100,000 or more obtained by blending a group-containing acrylic monomer with a glass transition temperature of preferably 25 ° C. or lower, more preferably 0 ° C. or lower is useful.
The acrylic polymer is not particularly limited, but (meth) such as butyl (meth) acrylate, ethyl (meth) acrylate, isooctyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. An acrylic ester polymer and a copolymer polymer using two or more of these (meth) acrylic esters are preferably used. Moreover, polar monomers may be copolymerized with these acrylic polymers. Examples of polar monomers include (meth) acrylic acid, 2-hydroxypropyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (meth) acrylamide, and 2-N, N-dimethylaminoethyl (meth). Mention may be made of monomers having polar functional groups such as carboxyl groups, hydroxyl groups, amide groups, amino groups, and epoxy groups, such as acrylates and glycidyl (meth) acrylates.
These acrylic polymers can be used alone as a pressure-sensitive adhesive, but are usually a pressure-sensitive adhesive composition containing a crosslinking agent. As the crosslinking agent, a divalent or polyvalent metal ion that forms a carboxylic acid metal salt with a carboxyl group, a polyamine compound that forms an amide bond with a carboxyl group, Examples include polyepoxy compounds and polyol compounds that form an ester bond with a carboxyl group, and polyisocyanate compounds that form an amide bond with a carboxyl group. Of these, polyisocyanate compounds are preferably used.
The means for increasing the storage elastic modulus of the pressure-sensitive adhesive is not particularly limited. For example, an oligomer, specifically, a urethane acrylate oligomer is added to the above-mentioned pressure-sensitive adhesive composition. A method is preferably employed. Furthermore, a method of irradiating and curing an adhesive composition containing such a urethane acrylate oligomer with energy rays is more preferably employed because it has a higher storage elastic modulus. A pressure-sensitive adhesive in which a urethane acrylate oligomer is blended or a pressure-sensitive adhesive with a separator obtained by coating it on a support film (separator) and curing it with ultraviolet rays is known and can be obtained from a pressure-sensitive adhesive manufacturer.
In order to adjust the adhesive force, cohesive force, viscosity, elastic modulus, glass transition temperature, etc. of the adhesive, if necessary, in addition to the above-mentioned polymer, crosslinking agent and oligomer, Appropriate additives such as natural and synthetic resins, tackifier resins, antioxidants, ultraviolet absorbers, dyes, pigments, antifoaming agents, corrosion inhibitors and photopolymerization initiators may be added. it can. Examples of the ultraviolet absorber include salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, nickel complex compounds, and the like.
Moreover, the adhesive used by the manufacturing method of this invention can mix | blend a light-diffusion agent, and can be used as a light diffusable adhesive. The light diffusing agent used here may be fine particles having a refractive index different from that of the polymer constituting the pressure-sensitive adhesive layer, and fine particles made of an inorganic compound or fine particles made of an organic compound (polymer) can be used.
Examples of the fine particles made of an inorganic compound include aluminum oxide (refractive index: 1.76) and silicon oxide (refractive index: 1.45). Examples of the fine particles comprising an organic compound (polymer) include melamine beads (refractive index: 1.57), polymethyl methacrylate beads (refractive index: 1.49), and methyl methacrylate / styrene copolymer resin beads. (Refractive index: 1.50 to 1.59), polycarbonate beads (refractive index: 1.55), polyethylene beads (refractive index: 1.53), polystyrene beads (refractive index: 1.6), polyvinyl chloride beads (Refractive index: 1.46) and silicone resin beads (refractive index: 1.46).
Since the resin composition constituting the pressure-sensitive adhesive layer including the acrylic polymer usually has a refractive index of about 1.4, the light diffusing agent to be blended is appropriately selected from those having a refractive index of about 1-2. Just choose. The difference in refractive index between the polymer and the light diffusing agent in the composition constituting the pressure-sensitive adhesive layer is usually 0.01 or more, and from the viewpoint of the brightness and visibility of the image display device, 0.01 to 0.00. 5 is preferred. The fine particles used as the light diffusing agent are preferably spherical and those close to monodisperse. For example, fine particles having an average particle diameter in the range of about 2 to 6 μm are preferably used.
The blending amount of the light diffusing agent is appropriately determined in consideration of the haze value required for the light diffusing pressure-sensitive adhesive layer in which it is blended, the brightness of the image display device to which it is applied, etc. The amount is about 3 to 30 parts by weight with respect to 100 parts by weight of the base polymer constituting the adhesive layer.
In addition, the haze value required for the light diffusive pressure-sensitive adhesive layer ensures the brightness of the image display device to which the composite polarizing plate obtained by using the haze value is applied, and hardly causes bleeding and blurring of the display image. Therefore, the range of 20 to 80% is preferable. The haze is a value defined by JIS K 7105 and expressed by (diffuse transmittance / total light transmittance) × 100 (%).
Furthermore, the thickness of the pressure-sensitive adhesive layer and the thickness of the light-diffusible pressure-sensitive adhesive layer are determined according to the adhesive strength and the like, but are usually in the range of 1 to 40 μm. Furthermore, this thickness is such that the composite polarizing plate produced using the composite polarizing plate maintains good workability and exhibits high durability, and the image display device using the composite polarizing plate is viewed from the front or obliquely. From the standpoint of maintaining the brightness of the image and making it difficult for bleeding and blurring of the display image to occur, 3 to 25 μm is more preferable.
In the second production method of the present invention, the surface of the polarizing film with the cut polarizing plate with a single-sided transparent protective film (the first embodiment and the second embodiment described later) or the surface of the retardation film (the first film described later). In the third embodiment, an adhesive layer is formed. The peelable film having adhesiveness bonded to the polarizing film is peeled off before forming the pressure-sensitive adhesive layer.
For the formation of the pressure-sensitive adhesive layer, the pressure-sensitive adhesive solution is applied to the surface of the polarizing film (first aspect, second aspect) or the surface of the retardation film (third aspect) of the cut polarizing plate with a single-sided transparent protective film. The method of applying and drying is preferably employed. In addition, a support film (separator) that has been subjected to a release treatment is prepared by forming a pressure-sensitive adhesive layer on the release treatment surface (separator-attached pressure-sensitive adhesive), and this is applied to the surface of the polarizing film or the retardation film. A method of bonding to the surface is also preferably employed.
As the pressure-sensitive adhesive solution, for example, a solution prepared by dissolving or dispersing the raw material constituting the pressure-sensitive adhesive composition in an organic solvent such as toluene or ethyl acetate to obtain a 10 to 40% by weight solution, for example. The pressure-sensitive adhesive layer thus formed may be laminated with a separator made of a resin film that has been treated with a silicone-based release agent.
Furthermore, when forming the pressure-sensitive adhesive layer on the surface of the polarizing film or retardation film of the cut polarizing plate with a single-sided transparent protective film, if necessary, adherence to the surface of the polarizing film or retardation film For example, a corona treatment or the like may be performed, or the same treatment may be performed on the surface of the pressure-sensitive adhesive layer bonded to the polarizing film surface.
In the 1st aspect in the 2nd manufacturing method of the composite polarizing plate of this invention, next, the said retardation film is bonded through the said adhesive layer to the polarizing film surface from which the said peelable film was removed. (Step (E)).
The method for laminating the polarizing plate with a single-sided transparent protective film on which the pressure-sensitive adhesive layer is laminated and the retardation film is not particularly limited, but for example, with a single-sided transparent protective film using a laminating roll or the like. A method of laminating the retardation film so that the slow axis of the retardation film is perpendicular or parallel to the polarizing transmission axis of the polarizing plate, and the slow axis of the retardation film is a predetermined angle with respect to the polarizing transmission axis of the polarizing film. The method of bonding so that it becomes is employ | adopted. In particular, the method of feeding a polarizing plate with a single-sided transparent protective film and a retardation film from each long roll and continuously bonding them together in the long side direction can produce a composite polarizing plate with high productivity. Preferably employed.
<Second aspect>
The second aspect in the second production method of the present invention includes the above-described step (A), step (C), step (D), step (B) and step (E) in this order. In (D), the said adhesive layer is laminated | stacked on the polarizing film surface of the said polarizing plate with a single-sided transparent protective film which passed through the said process (C).
In the second aspect of the second production method of the present invention, first, as in the first aspect described above, a transparent protective film is bonded to one side of the polarizing film, and the peeled surface has adhesiveness on the opposite side. The polarizing film with a single-sided transparent protective film is produced by bonding a conductive film (step (A)). The production of the transparent protective film and the polarizing film and the adhesion thereof are performed in the same manner as in the step (A) in the first aspect described above.
In the second embodiment of the second production method of the present invention, next, the peelable film is removed from the polarizing film surface (step (C)). And the adhesive layer which shows the storage elastic modulus of 0.1 Mpa or more in 80 degreeC is laminated | stacked on the polarizing film surface of the said polarizing plate with a single-sided transparent protective film which passed the said process (C) (process (D)). The removal of the peelable film and the formation of the pressure-sensitive adhesive layer are performed in the same manner as in step (C) and step (D) in the first aspect described above.
In the second aspect of the second production method of the present invention, next, the polarizing plate with a single-sided transparent protective film is cut along the longitudinal direction according to the width of the retardation film (step (B)). The cutting of the polarizing plate with a single-sided transparent protective film is performed in the same manner as in the step (B) in the first aspect described above. In this 2nd aspect, cutting of the polarizing plate with a single-sided transparent protective film is performed with the adhesive layer laminated | stacked.
In the 2nd aspect in the 2nd manufacturing method of this invention, the said retardation film is finally bonded through the said adhesive layer to the polarizing film surface from which the said peelable film was removed (process (E )). The production of the retardation film and the bonding thereof are performed in the same manner as in the step (E) in the first aspect described above. Thus, the composite polarizing plate obtained by the 2nd aspect becomes the structure similar to the composite polarizing plate obtained by the 1st aspect mentioned above.
<Third embodiment>
The third aspect of the second production method of the present invention includes the above-described step (A), step (B), step (C) and step (E) in this order. The agent layer is laminated on one side of the retardation film.
In the third aspect of the second production method of the present invention, first, as in the first aspect described above, a transparent protective film is bonded to one side of the polarizing film, and peeling is performed on the opposite side. The polarizing film with a single-sided transparent protective film is produced by bonding a conductive film (step (A)). The production of the transparent protective film and the polarizing film and the adhesion thereof are performed in the same manner as in the step (A) in the first aspect described above.
In the third aspect of the second production method of the present invention, next, the polarizing plate with a single-sided transparent protective film is cut along the longitudinal direction according to the width of the retardation film (step (B)). . Next, the peelable film is removed from the polarizing film surface (step (C)). The cutting of the polarizing plate with a single-sided transparent protective film and the removal of the peelable film are performed in the same manner as in the step (B) and the step (C) in the first aspect described above.
On the other hand, in the 3rd aspect in the 2nd manufacturing method of this invention, the adhesive layer which shows the storage elastic modulus of 0.1 Mpa or more in 80 degreeC is laminated | stacked on a retardation film surface (process (D)). The configuration of the retardation film and the production method thereof are the same as those described in the first embodiment. Moreover, lamination | stacking of the adhesive layer to a phase difference film can be performed like the process (D) of a 1st aspect. 3rd aspect WHEREIN: The timing at which a process (D) is implemented is not specifically limited, What is necessary is just to be implemented by the below-mentioned process (E) being made. That is, step (D) may be performed before step (A), in parallel with any of step (A), step (B) and step (C), or after any of them. You may go. In short, the retardation film with the pressure-sensitive adhesive layer may be supplied to the polarizing film surface from which the peelable film has been removed in the step (C).
Also in the third aspect of the second production method of the present invention, finally, the retardation film is bonded to the polarizing film surface from which the peelable film has been removed via the pressure-sensitive adhesive layer (step (E )). The production of the retardation film and the bonding thereof are performed in the same manner as described above. Thus, the composite polarizing plate obtained by the 3rd aspect becomes the structure similar to the composite polarizing plate obtained by the 1st aspect mentioned above.
In the 2nd manufacturing method of the composite polarizing plate of this invention, an adhesive layer may be further provided in the outer side of the retardation film bonded by the composite polarizing plate. The pressure-sensitive adhesive layer can be suitably used for bonding with other members such as a liquid crystal cell. This pressure-sensitive adhesive layer may be formed after producing the composite polarizing plate, or may be formed in advance on the retardation film before bonding the polarizing plate with a single-sided transparent protective film and the retardation film. The composite polarizing plate thus formed is usually arranged so that the retardation film side faces the liquid crystal cell when being bonded to the liquid crystal cell.
The composite polarizing plate manufactured by the manufacturing method of this invention can be set as a liquid crystal display device by bonding the retardation film side and a liquid crystal cell through an adhesive layer. The same type of polarizing plate or a known polarizing plate can be bonded to the back side of the liquid crystal display device to which the composite polarizing plate is bonded. The operation mode of the liquid crystal panel to be bonded is preferably an IPS mode in which optical compensation is satisfactorily compensated by the refractive index characteristics of the composite polarizing plate of the present invention.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited by these examples. In the examples, “part” and “%” representing the amount used or content are based on weight unless otherwise specified. In the following examples, the storage elastic modulus was measured by the following method.
[Method for measuring storage modulus]
The storage elastic modulus (G ′) of the pressure-sensitive adhesive is a disk-shaped test piece having a diameter of 8 mm × thickness of 1 mm made of the pressure-sensitive adhesive to be measured, and a dynamic viscoelasticity measuring device (Dynamic Analyzer RDA II: manufactured by REOMETRIC). The initial strain was set to 1N by a torsional shear method with a frequency of 1 Hz, and the measurement was performed under conditions of 23 ° C. and 80 ° C.
Moreover, in the Example and the comparative example, the following were used as an adhesive, an adhesive agent, a polarizing film, and retardation film.
(Adhesive sheet A)
The pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive sheet A is obtained by adding a urethane acrylate oligomer to a copolymer of butyl acrylate and acrylic acid, and further adding an isocyanate-based crosslinking agent. When the storage elastic modulus of this pressure-sensitive adhesive was measured by the above method, it was 0.40 MPa at 23 ° C. and 0.18 MPa at 80 ° C. In the following examples, the adhesive was applied to the release treatment surface of a 38 μm-thick polyethylene terephthalate film (separator) having been subjected to the release treatment by drying the organic solvent solution having the above composition, and then dried. The separator was used as a sheet-like pressure-sensitive adhesive (pressure-sensitive adhesive sheet A) in which a layer of pressure-sensitive adhesive A having a thickness of 15 μm was formed on the surface of the separator.
(Adhesive sheet B)
The pressure-sensitive adhesive sheet B is a commercially available sheet-like pressure-sensitive adhesive and does not contain a urethane acrylate oligomer. When the storage elastic modulus of the pressure-sensitive adhesive sheet B was measured by the above method, it was 0.05 MPa at 23 ° C. and 0.04 MPa at 80 ° C. In the following examples and comparative examples, as the pressure-sensitive adhesive sheet B, the layer of the pressure-sensitive adhesive sheet B having a thickness of 15 μm is formed on the release treatment surface of the 38 μm-thick polyethylene terephthalate film (separator) subjected to the release treatment. A commercially available adhesive with a separator was used.
(Adhesive A)
To 100 parts of water, 3 parts of carboxyl group-modified polyvinyl alcohol (Kuraray Poval KL318, manufactured by Kuraray Co., Ltd.) and water-soluble polyamide epoxy resin (Smiles Resin 650, manufactured by Sumika Chemtex Co., Ltd.) (solid content concentration 30%) Aqueous solution) 1.5 parts was added and dissolved to prepare adhesive A.
(Adhesive B)
100 parts of bis (3,4-epoxycyclohexylmethyl) adipate, 25 parts of diglycidyl ether of hydrogenated bisphenol A, and 4,4′-bis (diphenylsulfonio) diphenyl sulfide bis (hexafluorophosphate as a photocationic polymerization initiator ) (50% propylene carbonate solution) 2.2 parts (active ingredient amount) were mixed and defoamed to prepare an adhesive B made of a curable epoxy resin composition.
(Polarizing film)
A 75 μm-thick polyvinyl alcohol film made of polyvinyl alcohol having an average degree of polymerization of about 2400 and a saponification degree of 99.9 mol% or more was uniaxially stretched about 5 times by a dry method, and further maintained a tension state. The sample was immersed in pure water at 60 ° C. for 1 minute, and then immersed in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.05 / 5/100 at 28 ° C. for 60 seconds. Then, it was immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 8.5 / 8.5 / 100 at 72 ° C. for 300 seconds. Subsequently, it was washed with pure water at 26 ° C. for 20 seconds and then dried at 65 ° C. to obtain a polarizing film in which iodine was adsorbed and oriented on polyvinyl alcohol.
(Retardation film)
A film having a thickness of 80 μm obtained by longitudinally uniaxially stretching a norbornene resin film (Zeonor film, manufactured by Optes Co., Ltd.) made of a hydrogenated ring-opening polymer of a norbornene monomer was used as a retardation film precursor. The glass transition temperature of this film is 136 ° C., the photoelastic coefficient is 3.1 × 10 ⁻¹² m ² / N, the in-plane retardation value for light with a wavelength of 590 nm is 300 nm, and the retardation value in the thickness direction is 145 nm. there were. A shrink film (a biaxially stretched film (thickness: 60 μm) made of polypropylene resin having a transverse stretching ratio larger than the longitudinal stretching ratio) is bonded to both surfaces of this uniaxially stretched film via an acrylic adhesive layer having a thickness of 25 μm. It was. After that, while holding the width direction of the film with a pin tenter, the film is sequentially passed through an air circulation type thermostatic oven at 175 ° C ± 1 ° C and an air circulation type thermostatic oven at 160 ° C ± 1 ° C, and shrinks 0.70 times in the width direction. I let you. At this time, the shrinkage ratio in the longitudinal direction was 0.92. Then, the shrinkable film stuck on both surfaces was peeled off together with the pressure-sensitive adhesive layer to obtain a retardation film made of a norbornene resin. The retardation film obtained in this way, the thickness 107Myuemu, an in-plane retardation value 241.9nm with respect to light having a wavelength of 590 nm, _{N z} coefficient was 0.49. Moreover, the width | variety of the obtained retardation film was 720 mm.
<Example 1-1>
(Process (A))
A 40 μm-thick triacetyl cellulose film (transparent protective film) having a saponified surface is bonded to one surface of the polarizing film via an adhesive A, and the opposite surface has adhesiveness. As a peelable film, a polarizing film in which a polyethylene film having a self-adhesive surface (adhesive surface with a polarizing film) is bonded, the laminate is dried at 60 ° C., and a transparent protective film is bonded on one side is used. Obtained. The width of the obtained polarizing plate with a single-sided transparent protective film was 1490 mm. Further, the appearance of this polarizing plate was good without damage such as scratches and cracks, despite being subjected to heat of drying and friction with the transport roll.
(Process (B))
Next, this polarizing plate with a single-sided transparent protective film was cut (slit) along the longitudinal direction according to the size of the retardation film using a slitter (Model FN25, manufactured by Nishimura Seisakusho), and 720 mm. A polarizing plate with a single-side transparent protective film having a width was obtained. The appearance of this polarizing plate was good without damage such as scratches and cracks, despite being sheared at the time of slitting and friction with the transport roll.
(Process (C))
The retardation film was subjected to corona treatment at an irradiation amount of 16.8 kJ / m ² , and the adhesive B was applied to the treated surface. Next, the polyethylene film is peeled and removed from the polarizing plate cut in the step (B), immediately, the retardation film surface and the adhesive coating surface of the retardation film are laminated, and an ultraviolet irradiation device ( Lamp: Fusion D lamp, integrated light quantity 1000 mJ / cm ² ) was irradiated with ultraviolet rays and left at room temperature for 1 hour to obtain a composite polarizing plate of the present invention.
The appearance of the composite polarizing plate thus obtained was good with no floating or peeling of the film and no bubbles. Moreover, in obtaining the sheet | seat for liquid crystal cell bonding from this composite polarizing plate by cutting, 96.6% of the total area of the polarizing plate with a single-sided protective film could be used.
The retardation film surface of the obtained composite polarizing plate is fixed to soda glass (used as a substitute for a liquid crystal cell) with a commercially available acrylic pressure-sensitive adhesive sheet, and subjected to autoclave treatment at 50 ° C. for 20 minutes to make the composite polarizing plate into glass. It was made to adhere to a board. In this state, a heat shock test was performed by placing in an atmosphere of −35 ° C. for 30 minutes, then moving to an atmosphere of + 85 ° C. and placing for 30 minutes as one cycle, and repeating this for 100 cycles. The composite polarizing plate of Example 1-1 was maintained in a good state with no defects observed after the test.
<Example 1-2>
(Production and evaluation of liquid crystal display devices)
Remove the backlight from the liquid crystal display device (W32L-H9000, manufactured by Hitachi, Ltd.) including the liquid crystal cell in the IPS mode, remove the polarizing plate arranged on the backlight side of the liquid crystal cell, and remove the glass surface. Washed. Next, on the backlight side of the liquid crystal cell, the retardation film is a liquid crystal so that the absorption axis of the composite polarizing plate obtained in Example 1-1 is the same as the absorption axis of the original polarizing plate. A liquid crystal panel was prepared by adhering via an acrylic pressure-sensitive adhesive so as to be on the cell side. Finally, the backlight that had been removed once was assembled again to produce a liquid crystal display device.
With respect to this liquid crystal display device, the contrast ratio at an azimuth angle of 45 ° and a polar angle of 60 ° was measured 30 minutes after the backlight was turned on. As a result, a contrast ratio of 282 was shown.
<Comparative Example 1-1>
A composite polarizing plate was produced in the same manner as in Example 1-1 except that the polarizing plate with a single-sided transparent protective film was not cut. The appearance of the composite polarizing plate thus obtained was good with no film floating, peeling or bubbles. However, in obtaining a sheet in the same manner as in Example 1-1, only 48.3% of the total area of the composite polarizing plate could be used.
<Comparative Example 1-2>
A composite polarizing plate was prepared in the same manner as in Example 1-1, except that a polyethylene film having a self-adhesive surface (adhesive surface with a polarizing film) was not used when the polarizing plate with a single-sided transparent protective film was prepared. . The appearance of the produced composite polarizing plate was not practically used because the polarizing film was damaged during the production of the polarizing plate with a single-sided transparent protective film and when the polarizing plate with a single-sided transparent protective film was cut.
<Example 1-3>
(Process (A))
A 40 μm thick triacetyl cellulose film (transparent protective film) having a surface subjected to saponification treatment is bonded to one surface of the polarizing film via an adhesive B, and the opposite surface has adhesiveness. As a peelable film, a polyethylene film having a self-adhesive surface (adhesion surface with a polarizing film) is bonded, and ultraviolet irradiation is performed with an ultraviolet irradiation device (lamp: Fusion D lamp, integrated light quantity 1000 mJ / cm ² ). And allowed to stand at room temperature for 1 hour to obtain a polarizing plate having a transparent protective film bonded on one side. The width of the obtained polarizing plate with a single-sided transparent protective film was 1490 mm. The appearance of the polarizing plate was good without damage such as scratches and cracks, despite being subjected to friction with the transport roll.
(Process (B))
Next, this polarizing plate with a single-sided transparent protective film was cut in the same manner as in Example 1-1 to obtain a polarizing plate with a single-sided transparent protective film having a width of 720 mm. The appearance of the polarizing plate with a single-sided transparent protective film after the cutting was good without damage such as scratches and cracks, despite being sheared at the time of slitting and friction with the transport roll.
(Process (C))
The composite polarizing plate of the present invention was obtained in the same manner as in the step (C) of Example 1-1. The appearance of the composite polarizing plate thus obtained was good with no floating or peeling of the film and no bubbles. Moreover, in obtaining the sheet | seat for liquid crystal cell bonding from this composite polarizing plate by cutting, 96.6% of the total area of the polarizing plate with a single-sided protective film could be used.
The retardation film surface of the obtained composite polarizing plate is fixed to soda glass (used as a substitute for a liquid crystal cell) with an adhesive sheet B, and subjected to autoclave treatment at 50 ° C. for 20 minutes to adhere the composite polarizing plate to the glass plate. Let In this state, a heat shock test is performed by placing in an atmosphere of −35 ° C. for 30 minutes, then moving to an atmosphere of + 85 ° C. and placing for 30 minutes as one cycle, and repeating this for 100 cycles. In the composite polarizing plate of Example 1-3, no defects were observed even after the test, and the good state was maintained.
<Example 1-4>
In Example 1-2, the same procedure as in Example 1-2 was performed except that the composite polarizing plate obtained in Example 1-3 was used instead of the composite polarizing plate obtained in Example 1-1. Thus, a liquid crystal display device was produced. With respect to this liquid crystal display device, the contrast ratio at an azimuth angle of 45 ° and a polar angle of 60 ° was measured 30 minutes after the backlight was turned on. As a result, a contrast ratio of 282 was shown.
<Example 2-1>
(Process (A))
A 40 μm-thick triacetyl cellulose film (transparent protective film) having a saponified surface is bonded to one surface of the polarizing film via an adhesive A, and the opposite surface has adhesiveness. As a peelable film, a polarizing film in which a polyethylene film having a self-adhesive surface (adhesive surface with a polarizing film) is bonded, the laminate is dried at 60 ° C., and a transparent protective film is bonded on one side is used. Obtained. The width of the obtained polarizing plate with a single-sided transparent protective film was 1490 mm. Further, the appearance of this polarizing plate was good without damage such as scratches and cracks, despite being subjected to heat of drying and friction with the transport roll.
(Process (B))
Next, this polarizing plate with a single-sided transparent protective film was cut (slit) along the longitudinal direction according to the size of the retardation film using a slitter (Model FN25, manufactured by Nishimura Seisakusho), and 720 mm. A polarizing plate with a single-side transparent protective film having a width was obtained. The appearance of this polarizing plate was good without damage such as scratches and cracks, despite being sheared at the time of slitting and friction with the transport roll.
(Process (C), Process (D))
The polyethylene film was peeled and removed from the polarizing plate cut in the step (B), and the pressure-sensitive adhesive sheet A was immediately bonded onto the surface of the polarizing film to laminate a pressure-sensitive adhesive layer.
(Process (E))
After the corona treatment was applied to the retardation film at an irradiation amount of 16.8 kJ / m ² , the pressure-sensitive adhesive provided with the corona-treated surface and the polarizing plate slit in the step (B) in the step (D) Bonding via the layers gave a composite polarizing plate.
The appearance of the composite polarizing plate thus obtained was good with no film floating, peeling or bubbles. Moreover, when obtaining the sheet | seat for liquid crystal cell bonding from this composite polarizing plate by cutting, 96.6% was able to be used in the whole area of a composite polarizing plate.
The retardation film surface of the obtained composite polarizing plate is fixed to soda glass (used as a substitute for a liquid crystal cell) with an adhesive sheet B, and subjected to autoclave treatment at 50 ° C. for 20 minutes to adhere the composite polarizing plate to the glass plate. I let you. In this state, a heat shock test was performed by placing in an atmosphere of −35 ° C. for 30 minutes, then moving to an atmosphere of + 85 ° C. and placing for 30 minutes as one cycle, and repeating this for 100 cycles. The composite polarizing plate of Example 2-1 maintained a good state with no defects observed even after the test.
<Example 2-2>
(Production and evaluation of liquid crystal display devices)
Remove the backlight from the liquid crystal display device (W32L-H9000, manufactured by Hitachi, Ltd.) including the liquid crystal cell in the IPS mode, remove the polarizing plate arranged on the backlight side of the liquid crystal cell, and remove the glass surface. Washed. Next, the composite polarizing plate obtained in Example 2-1 was placed on the backlight side of the liquid crystal cell so that the absorption axis was the same as the absorption axis of the original polarizing plate, and the retardation film was a liquid crystal. A liquid crystal panel was prepared by adhering via an acrylic pressure-sensitive adhesive so as to be on the cell side. Finally, the backlight that had been removed once was assembled again to produce a liquid crystal display device.
With respect to this liquid crystal display device, the contrast ratio at an azimuth angle of 45 ° and a polar angle of 60 ° was measured 30 minutes after the backlight was turned on. As a result, a contrast ratio of 282 was shown.
<Comparative Example 2-1>
A composite polarizing plate was produced in the same manner as in Example 2-1, except that the polarizing plate with a single-sided transparent protective film was not cut. The appearance of the composite polarizing plate thus obtained was good with no film floating, peeling or bubbles. However, in obtaining the sheet in the same manner as in Example 2-1, only 48.3% of the total area of the composite polarizing plate could be used.
<Comparative Example 2-2>
A composite polarizing plate was produced in the same manner as in Example 2-1, except that a polyethylene film having a self-adhesive surface (adhesive surface with a polarizing film) was not used when producing a polarizing plate with a single-sided transparent protective film. . The appearance of the produced composite polarizing plate was not practically used because the polarizing film was damaged during the production of the polarizing plate with a single-sided transparent protective film and when the polarizing plate with a single-sided transparent protective film was cut.
<Example 2-3>
(Process (A))
A 40 μm thick triacetyl cellulose film (transparent protective film) having a surface subjected to saponification treatment is bonded to one surface of the polarizing film via an adhesive B, and the opposite surface has adhesiveness. As a peelable film, a polyethylene film having a self-adhesive surface (bonding surface with a polarizing film) is bonded, and ultraviolet irradiation is performed with an ultraviolet irradiation device (lamp: Fusion D lamp, integrated light quantity: 1000 mJ / cm ² ). And left at room temperature for 1 hour to obtain a polarizing plate having a transparent protective film bonded on one side. The width of the obtained polarizing plate with a single-sided transparent protective film was 1490 mm. Further, the appearance of this polarizing plate was good without damage such as scratches and cracks despite being subjected to friction with the transport roll.
(Process (B))
Subsequently, this polarizing plate with a single-sided transparent protective film was cut in the same manner as in Example 2-1, to obtain a polarizing plate with a single-sided transparent protective film having a width of 720 mm. The appearance of the polarizing plate with a single-sided transparent protective film after the cutting was good without damage such as scratches and cracks, despite being sheared at the time of slitting and friction with the transport roll.
(Process (C), Process (D))
The polyethylene film was peeled and removed from the polarizing plate slit in the step (B), and immediately, the pressure-sensitive adhesive sheet A was bonded onto the surface of the polarizing film to laminate a pressure-sensitive adhesive layer.
(Process (E))
After the corona treatment was applied to the retardation film at an irradiation amount of 16.8 kJ / m ² , the pressure-sensitive adhesive provided with the corona-treated surface and the polarizing plate slit in the step (B) in the step (D) Bonding via the layers gave a composite polarizing plate.
The appearance of the composite polarizing plate thus obtained was good with no film floating, peeling or bubbles. Moreover, in obtaining the sheet | seat for liquid crystal cell bonding from this composite polarizing plate by cutting, 96.6% of the total area of the polarizing plate with a single-sided protective film could be used.
The retardation film surface of the obtained composite polarizing plate is fixed to soda glass (used as a substitute for a liquid crystal cell) with an adhesive sheet B, and subjected to autoclave treatment at 50 ° C. for 20 minutes to adhere the composite polarizing plate to the glass plate. I let you. In this state, a heat shock test was performed by placing in an atmosphere of −35 ° C. for 30 minutes, then moving to an atmosphere of + 85 ° C. and placing for 30 minutes as one cycle, and repeating this for 100 cycles. In the composite polarizing plate of Example 2-3, no defects were observed even after the test, and the good state was maintained.
<Example 2-4>
A liquid crystal display device was produced in the same manner as in Example 2-2 except that the composite polarizing plate obtained in Example 2-3 was used instead of the composite polarizing plate obtained in Example 2-1. . With respect to this liquid crystal display device, the contrast ratio at an azimuth angle of 45 ° and a polar angle of 60 ° was measured 30 minutes after the backlight was turned on. As a result, a contrast ratio of 282 was shown.
<Comparative Example 2-3>
A composite polarizing plate was prepared in the same manner as in Example 2-1, except that the pressure-sensitive adhesive sheet A used in the step (D) was changed to the pressure-sensitive adhesive sheet B. The appearance of the composite polarizing plate thus obtained was good with no film floating, peeling or bubbles. Moreover, when obtaining the sheet | seat for liquid crystal cell bonding from this composite polarizing plate by cutting, 96.6% was able to be used in the whole area of a composite polarizing plate.
The retardation film surface of the obtained composite polarizing plate is fixed to soda glass (used as a substitute for a liquid crystal cell) with an adhesive sheet B, and subjected to autoclave treatment at 50 ° C. for 20 minutes to adhere the composite polarizing plate to the glass plate. I let you. In this state, a heat shock test was performed by placing in an atmosphere of −35 ° C. for 30 minutes, then moving to an atmosphere of + 85 ° C. and placing for 30 minutes as one cycle, and repeating this for 100 cycles. In the polarizing plate of Comparative Example 2-3, bubbles were generated in the pressure-sensitive adhesive layer between the retardation film and the glass after the test, which was not practical.
<Comparative Example 2-4>
A composite polarizing plate was produced in the same manner as in Example 2-3, except that the pressure-sensitive adhesive sheet A used in the step (D) was changed to the pressure-sensitive adhesive sheet B. The appearance of the composite polarizing plate thus obtained was good with no film floating, peeling or bubbles. Moreover, when obtaining the sheet | seat for liquid crystal cell bonding from this composite polarizing plate by cutting, 96.6% was able to be used in the whole area of a composite polarizing plate.
The retardation film surface of the obtained composite polarizing plate is fixed to soda glass (used as a substitute for a liquid crystal cell) with an adhesive sheet B, and subjected to autoclave treatment at 50 ° C. for 20 minutes to adhere the composite polarizing plate to the glass plate. I let you. In this state, a heat shock test was performed by placing in an atmosphere of −35 ° C. for 30 minutes, then moving to an atmosphere of + 85 ° C. and placing for 30 minutes as one cycle, and repeating this for 100 cycles. In the polarizing plate of Comparative Example 2-3, bubbles were generated in the pressure-sensitive adhesive layer between the retardation film and the glass after the test, which was not practical.
<Example 2-5>
(Process (A))
A 40 μm-thick triacetyl cellulose film (transparent protective film) having a saponified surface is bonded to one surface of the polarizing film via an adhesive A, and the opposite surface has adhesiveness. As a peelable film, a polarizing film in which a polyethylene film having a self-adhesive surface (adhesive surface with a polarizing film) is bonded, the laminate is dried at 60 ° C., and a transparent protective film is bonded on one side is used. Obtained. The width of the obtained polarizing plate with a single-sided transparent protective film was 1490 mm. In addition, the appearance of this polarizing plate was good without damage such as scratches and cracks, despite the heat of drying and the friction with the transport roll.
(Process (C), Process (D))
Subsequently, the polyethylene film was peeled and removed from the polarizing plate with a single-sided transparent protective film, and immediately, the pressure-sensitive adhesive sheet A was bonded onto the surface of the polarizing film to laminate a pressure-sensitive adhesive layer.
(Process (B))
Using a slitter (Model FN25, manufactured by Nishimura Seisakusho Co., Ltd.), the polarizing plate with a single-side transparent protective film was cut (slit) along the longitudinal direction according to the size of the retardation film, A polarizing plate with a single-sided transparent protective film was obtained. The appearance of this polarizing plate was good without damage such as scratches and cracks, despite being sheared at the time of slitting and friction with the transport roll.
(Process (E))
After the corona treatment was applied to the retardation film at an irradiation amount of 16.8 kJ / m ² , the pressure-sensitive adhesive provided with the corona-treated surface and the polarizing plate slit in the step (B) in the step (D) Bonding via the layers gave a composite polarizing plate.
The appearance of the composite polarizing plate thus obtained was good without the film floating, peeling, or bubbles. Moreover, in obtaining the sheet | seat for liquid crystal cell bonding from this composite polarizing plate by cutting, 96.6% was able to be used in the whole area of a composite polarizing plate.
<Example 2-6>
(Process (A))
A 40 μm-thick triacetyl cellulose film (transparent protective film) having a saponified surface is bonded to one surface of the polarizing film via an adhesive A, and the opposite surface has adhesiveness. As a peelable film, a polarizing film in which a polyethylene film having a self-adhesive surface (adhesive surface with a polarizing film) is bonded, the laminate is dried at 60 ° C., and a transparent protective film is bonded on one side is used. Obtained. The width of the obtained polarizing plate with a single-sided transparent protective film was 1490 mm. In addition, the appearance of this polarizing plate was good without damage such as scratches and cracks, despite the heat of drying and the friction with the transport roll.
(Process (B))
Next, this polarizing plate with a single-sided transparent protective film was cut (slit) along the longitudinal direction according to the size of the retardation film using a slitter (Model FN25, manufactured by Nishimura Seisakusho), 720 mm A polarizing plate with a single-side transparent protective film having a width was obtained. The appearance of this polarizing plate was good without damage such as scratches and cracks, despite being sheared at the time of slitting and friction with the transport roll.
(Process (D))
After the corona treatment was applied to the retardation film at an irradiation amount of 16.8 kJ / m ² , the pressure-sensitive adhesive sheet A was bonded on the corona-treated surface to laminate the pressure-sensitive adhesive layer.
(Process (C), Process (E))
The polyethylene film was peeled off from the polarizing plate slit in the step (B). And after giving a corona treatment with the irradiation amount of 16.8 kJ / m < ² > to the polarizing film surface after peeling a polyethylene film, and the adhesive layer side provided in the phase difference film at the said process (D), a polarizing plate and phase difference The film was bonded via an adhesive layer on a retardation film to obtain a composite polarizing plate.
The appearance of the composite polarizing plate thus obtained was good without the film floating, peeling, or bubbles. Moreover, in obtaining the sheet | seat for liquid crystal cell bonding from this composite polarizing plate by cutting, 96.6% was able to be used in the whole area of a composite polarizing plate.
It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

The composite polarizing plate of the present invention can be widely used as an optical member in various liquid crystal display devices. For example, it can be used in large liquid crystal display devices such as televisions, computer displays, car navigation systems, mobile phones, and mobile terminal devices. It can be used as an optical member in the medium- and small-sized liquid crystal display device used.

Claims

(A) a step of pasting a transparent protective film on one side of the polarizing film, pasting a peelable film having adhesiveness on the opposite side, and producing a polarizing plate with a single-sided transparent protective film;
(B) cutting the polarizing plate with a single-sided transparent protective film along the longitudinal direction according to the width of the retardation film;
(C) An epoxy resin that removes the peelable film of the polarizing plate with the single-sided transparent protective film cut in the step (B) and cures the polarizing film surface and the retardation film by irradiation with active energy rays or heating. The manufacturing method of a composite polarizing plate including the process of bonding using the epoxy resin composition containing this.
The production method according to claim 1, wherein the epoxy resin contains a compound having at least one epoxy group bonded to an alicyclic ring in the molecule.
(A) a step of pasting a transparent protective film on one side of the polarizing film, pasting a peelable film having adhesiveness on the opposite side, and producing a polarizing plate with a single-sided transparent protective film;
(B) cutting the polarizing plate with a single-sided transparent protective film along the longitudinal direction according to the width of the retardation film;
(C) removing the peelable film from the polarizing film surface;
(D) An adhesive layer exhibiting a storage elastic modulus of 0.1 MPa or more at 80 ° C. on one side of the retardation film or the polarizing film side of the polarizing plate with the one-side transparent protective film that has undergone the step (C). Laminating steps;
(E) The manufacturing method of a composite polarizing plate including the process of bonding the said retardation film through the said adhesive layer on the polarizing film surface from which the said peelable film was removed.
The process (A), the process (B), the process (C), the process (D), and the process (E) are included in this order. In the process (D), the pressure-sensitive adhesive layer includes the process (C). The manufacturing method of Claim 3 laminated | stacked on the polarizing film surface of the polarizing plate with the said single-sided transparent protective film which passed.
The process (A), the process (C), the process (D), the process (B), and the process (E) are included in this order. In the process (D), the pressure-sensitive adhesive layer includes the process (C). The manufacturing method of Claim 3 laminated | stacked on the polarizing film surface of the polarizing plate with the said single-sided transparent protective film which passed.
The process (A), the process (B), the process (C) and the process (E) are included in this order, and in the process (D), the pressure-sensitive adhesive layer is laminated on one surface of the retardation film. The manufacturing method according to claim 3.
The method according to any one of claims 3 to 6, wherein the pressure-sensitive adhesive layer has a thickness of 1 to 40 µm.
The retardation film, the in-plane slow axis direction, the in-plane fast axis direction and n the refractive index in the thickness direction, respectively x, and n y and n z, when the thickness is d, the light of wavelength 590nm The production method according to any one of claims 1 to 7, which is an olefin resin film satisfying the formulas (1) and (2).
100nm ≦ (n x -n y) × d ≦ 300nm (1)
0.1 ≦ (n x -n z) / (n x -n y) ≦ 0.7 (2)
The manufacturing method according to claim 8, wherein the olefin-based resin film is made of a resin mainly including a structural unit derived from an alicyclic olefin.
10. The production method according to claim 1, wherein the retardation film has a width that is 10% or more smaller than the width of the polarizing plate with a single-sided transparent protective film.
The production method according to any one of claims 1 to 10, wherein the polarizing film and the transparent protective film are bonded with a water-soluble adhesive containing a polyvinyl alcohol resin and an epoxy resin.
The polarizing film and the transparent protective film are bonded to each other with an adhesive made of a solventless resin composition containing an epoxy resin that is cured by irradiation with active energy rays or heating. Manufacturing method.
The production method according to claim 12, wherein the epoxy resin contains a compound having one or more epoxy groups bonded to an alicyclic ring in the molecule.
14. The production method according to claim 1, wherein the thickness of the transparent protective film is 20 to 300 μm.