JP2013186252A - Method for manufacturing polarizing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a polarizing plate capable of suppressing a curl even if a first transparent protective film and a second transparent protective film have a larger dimensional change rate.SOLUTION: A manufacturing method is to obtain a long polarizing plate through laminating a first transparent protective film on one side of a polarizer with an adhesive agent therebetween, and a second transparent protective film on the other side thereof with an adhesive agent therebetween. If a dimensional change rate (%) of the first transparent protective film is L1 and a dimensional change rate (%) of the second transparent protective film is L2, an absolute value of a difference (L1-L2) satisfies 0.10 or larger, and in a crosswise direction of the polarizer, a width w (mm) of the adhesive agent being present from an end portion of the polarizer to the outside satisfies 0≤w≤75.

Description

  The present invention relates to a method for producing a polarizing plate. The polarizing plate obtained by the production method of the present invention can form an image display device such as a liquid crystal display device, an organic EL display device, or a PDP alone or as an optical film obtained by laminating the polarizing plate.

  In a liquid crystal display device, it is indispensable to dispose polarizers on both sides of a glass substrate on which a liquid crystal panel surface is formed because of its image forming method. In general, a polarizer is obtained by dyeing a polyvinyl alcohol film with a dichroic material such as iodine, cross-linking with a cross-linking agent, and forming a film by uniaxial stretching. In addition, since the polyvinyl alcohol film uses a hydrophilic polymer, it is very easily deformed particularly under humidified conditions. Moreover, since the mechanical strength of the film itself is weak, there is a problem that the film is torn. Therefore, a polarizing plate is used in which a transparent protective film such as triacetyl cellulose is bonded to both sides or one side of a polarizer with a polyvinyl alcohol-based adhesive or the like to supplement strength.

  As a manufacturing method of a general polarizing plate, a transparent protective film washed with water is arranged on both surfaces of a polarizer, and the sheet is passed between a pair of rolls via an adhesive between the polarizer and the transparent protective film. Later, a method of drying in an oven is known.

  The transparent protective film is likely to undergo dimensional changes during the drying stage. However, as described above, in a method for producing a general polarizing plate, a drying process is performed after a transparent protective film is bonded to a polarizer using an adhesive. In this drying process, when a dimensional change occurs in the transparent protective film or the like and curling occurs in the polarizing plate, running of the polarizing plate is deteriorated in a continuous manufacturing process of the polarizing plate. In particular, when the dimensional change rate of the transparent protective film to be bonded to both surfaces of the polarizer is different, curling is likely to occur, and the working efficiency is lowered.

  As a method for suppressing curling of the polarizing plate, for example, it has been proposed to reduce the thickness of the transparent protective film (Patent Document 1). Further, in manufacturing a polarizing plate, it has been proposed that after one transparent protective film is bonded to one side of a polarizer, another transparent protective film is bonded to the other side (Patent Document 2). ).

JP 2001-235625 A JP 2004-117482 A

  Although the polarizing plates obtained by Patent Documents 1 and 2 have a curling suppression effect, the structure of the polarizing plate itself has not been changed, and studies have been made from the viewpoint of suppressing the occurrence of curling at the end of the polarizing plate. Not.

  The present invention is a method for producing a polarizing plate by laminating a first transparent protective film on one side of a polarizer via an adhesive and a second transparent protective film on the other side via an adhesive. And even if it is a case where the difference of the dimensional change rate of a 1st transparent protective film and a 2nd transparent protective film is large, it aims at providing the manufacturing method of the polarizing plate which can suppress curl.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the object can be achieved by the following method for producing a polarizing plate, and have completed the present invention.

That is, the present invention is a long polarizing plate in which a first transparent protective film is bonded to one surface of a polarizer via an adhesive, and a second transparent protective film is bonded to the other surface via an adhesive. A method of manufacturing
The first transparent protective film and the second transparent protective film have a dimensional change rate (%) of the first transparent protective film of L1, and a dimensional change rate of the second transparent protective film of L2 (%). The absolute value of the difference in dimensional change rate (L1-L2) satisfies 0.10 or more,
And the width | variety of a polarizer is below the width | variety of a 1st transparent protective film and a 2nd transparent protective film, Comprising: The adhesive which exists toward the outer side from the edge part of the both sides of a polarizer in the width direction of a polarizer The present invention relates to a method for producing a polarizing plate, wherein the width w (mm) of the agent satisfies 0 ≦ w ≦ 75.

  In the manufacturing method of the said polarizing plate, the thing from which the width | variety of a 1st transparent protective film differs from a 2nd transparent protective film can be used.

  In the manufacturing method of the polarizing plate of the present invention, a transparent protective film to be bonded to both surfaces of the polarizer uses a film having a large difference in dimensional change rate. In the conventional manufacturing method, curling occurs at the end of the polarizing plate. easy. Such curling occurs when a transparent protective film having a width wider than that of the polarizer is bonded to the polarizer with an adhesive, so that the end of the polarizing plate is transparently protected by the adhesive without using the polarizer. It was found that the cause was that the film was restrained.

  In the method for producing a polarizing plate of the present invention, the width of the polarizer used is equal to or less than the width of the transparent protective film, but in the width direction of the polarizer, the adhesive is applied outward from the end of the polarizer. The adhesive is applied so that it does not have or has an adhesive with a predetermined width or less. Thus, in the manufacturing method of the polarizing plate of this invention, the transparent protective film arrange | positioned on both surfaces of a polarizer is an adhesive agent without passing through a polarizer outside the edge part of the width direction of a polarizer. The part to be bonded is controlled to be small. As a result, the polarizer serves as a support in the central portion of the polarizing plate to suppress curling, and the width of the adhesive that causes curling is small even outside the end in the width direction of the polarizer. Controlled. Therefore, even when a transparent protective film having a large dimensional change rate difference is used on both surfaces of the polarizer, it is considered that curling occurring at the end of the polarizing plate can be suppressed.

  Moreover, in the manufacturing method of the polarizing plate of this invention, the curl which arises in the edge part of the width direction of a polarizing plate is suppressed effectively by using the transparent protective film from which width | variety differs as a transparent protective film provided in both surfaces of a polarizer. be able to. When the width of the transparent protective film used on both sides of the polarizer is different, the wider transparent protective film can be expanded and contracted freely in the width direction, effectively curling the edges of the polarizing plate in the width direction. Can be suppressed.

  According to the method for producing a polarizing plate of the present invention, even when transparent protective films provided on both sides of the polarizer have different dimensional change rates, the occurrence of curling in the production stage of the polarizing plate can be suppressed. A polarizing plate can be produced stably. As a result, the degree of freedom in selecting a transparent protective film is increased, a wide range of optical designs are possible, and high resolution and high contrast image display devices such as liquid crystal display devices (LCD) and electroluminescence display devices (ELD). Can be realized.

It is sectional drawing which shows an example of embodiment which concerns on the manufacturing method of the polarizing plate of this invention. It is sectional drawing which shows an example of other embodiment which concerns on the manufacturing method of the polarizing plate of this invention. It is sectional drawing which shows an example of other embodiment which concerns on the manufacturing method of the polarizing plate of this invention. It is sectional drawing which shows an example of other embodiment which concerns on the manufacturing method of the polarizing plate of this invention.

Hereinafter, embodiments according to the method for producing a polarizing plate of the present invention will be described with reference to the drawings. 1 to 4 are sectional views showing an example of a polarizing plate according to the production method of the present invention. As shown in FIGS. 1 to 4, in the method for producing a polarizing plate of the present invention, the first transparent protective film T1 and the second transparent protective film are provided on both surfaces of the polarizer P via adhesives (a1, a2). T2 is provided. The width _{W p} of the polarizer P is not more than the width _{W t2} width _{W t1} and the second transparent protective film T2 of the first transparent protective film T1. In the polarizing plates of FIG. 1 and FIG. 2, the case where the widths W _t1 and W _t2 are the same is shown. In the polarizing plates of FIGS. 3 and 4, the case of the width W _t1 > W _t2 is shown.

In addition, in the polarizing plates described in FIGS. 1 and 3, the first transparent protective film T <b> 1 and the second transparent protective film T <b> 2 have the polarizer P interposed therebetween on the both sides in the width direction of the polarizer. It is a case where it has pasted together by adhesives (a3). In the polarizing plates shown in FIGS. 2 and 4, the width W _{p of the} polarizer and the width of the adhesive (a 1, a 2) coincide with each other. This is the case without an adhesive.

  In the polarizing plate described in FIG. 1 and FIG. 3, the adhesive (a3) exists in the width direction of the polarizer P from the ends on both sides of the polarizer P toward the outside. The adhesive (a3) bonds the first transparent protective film T1 and the second transparent protective film T2. The widths w of the adhesive (a3) existing outside the ends on both sides of the polarizer P are represented as w1 and w2, respectively. The widths w1 and w2 of the adhesive (a3) may be the same or different.

In the polarizing plates shown in FIGS. 1 and 3, if the width w (w1, w2) of the adhesive (a3) is too wide, it is not preferable for good running of the polarizing plate. The width w (mm) of the adhesive (a3) is controlled so that 0 ≦ w ≦ 75. The width w of the adhesive (a3) is preferably 10 ≦ w ≦ 75 from the viewpoint of the manufacturing process, and more preferably 10 ≦ w ≦ 60 from the viewpoint of curling suppression. Incidentally, FIG. 1, the polarizing plate according to FIG. 3, in the case of w = 0, the width of the width W _p and the adhesive of the polarizer (a1, a2) coincide, 2, polarization according to FIG. 4 Corresponds to the board.

The width W _p (mm) of the polarizer is usually preferably 300 to 2000 mm. On the other hand, the width _W t2 width _W t1 (mm) and the second transparent protective film T2 of the first transparent protective film T1 (mm) is the width of the polarizer P _W p (mm) or more. Usually, it is preferable that the width | variety of a 1st transparent protective film and a 2nd transparent protective film is 350-2300 mm.

The width _W t2 width _W t1 (mm) and the second transparent protective film T2 of the first transparent protective film T1 (mm) is a width _W p (mm of polarizer P in the polarizing plate according to FIG. 1 ) to is longer than a length obtained by adding the width w of the adhesive (a3), it is longer than the width W _{p (mm)} of the polarizer P in the polarizing plate according to FIG.

  In the method for producing a polarizing plate of the present invention, the first transparent protective film T1 and the second transparent protective film T2 have a dimensional change rate (%) of the first transparent protective film T1 of L1 and the second transparent protective film T1. When the dimensional change rate (%) of the transparent protective film T2 is L2, the absolute value of the dimensional change rate difference (L1−L2) is 0.10 or more, and is effectively applied when the dimensional change rate is large. The In addition, it is preferable that the absolute value of the said dimensional change rate difference (L1-L2) is 0.15 or less from a viewpoint of runnability. The selection of the first transparent protective film T1 and the second transparent protective film T2 so that the absolute value of the dimensional change rate difference (L1-L2) is 0.10 or more is of different materials and different thicknesses. It can adjust by using.

Further, as shown in FIGS. 3 and 4, the polarizing plate according to the production method of the present invention, the width W _t1 and the width W _t1 of the second transparent protective film T2 of the first transparent protective film T1 is different Things can be used. By using transparent protective films having different widths, curling of the polarizing plate can be suppressed even when transparent protective films having different dimensional change rates are used. The width W _t1 (mm) of the first transparent protective film T1 is longer than the length obtained by adding the width w of the adhesive (a3) to the width W _p (mm) of the polarizer P in the polarizing plate illustrated in FIG. In the polarizing plate shown in FIG. 4, it is longer than the width W _p (mm) of the polarizer P.

As shown in FIG. 1 to FIG. 4, an aspect in which the width W _{t of} any at least one transparent protective film is longer than the length of the polarizer W _p and the width w of the adhesive (a3) is added. This is preferable for effectively suppressing curling occurring at the end in the width direction of the polarizing plate.

  3 and FIG. 4, in the case where the first transparent protective film T1 is wider than the second transparent protective film T2, the first transparent protective film is a second transparent protective film. In order to suppress curling, it is effective to use a material that satisfies a dimensional change rate (%) larger than that of the transparent protective film T2, that is, L1> L2.

  The polarizer, transparent protective film, and adhesive used for the polarizing plate of the present invention are described below.

  The polarizer is not particularly limited, and various types can be used. Examples of the polarizer include hydrophilic polymers such as polyvinyl alcohol film, partially formalized polyvinyl alcohol film, and ethylene / vinyl acetate copolymer partially saponified film, and two colors such as iodine and dichroic dye. Examples include polyene-based oriented films such as those obtained by adsorbing a functional material and uniaxially stretched, polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, a polarizer composed of a polyvinyl alcohol film and a dichroic material such as iodine is preferable. The thickness of these polarizers is not particularly limited, but is generally about 5 to 80 μm. The thickness of the polarizer is preferably 15 to 35 μm.

  A polarizer obtained by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching it can be prepared, for example, by immersing polyvinyl alcohol in an aqueous solution of iodine and stretching it 3 to 7 times the original length. If necessary, it can be immersed in an aqueous solution of boric acid or potassium iodide. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing. In addition to washing the polyvinyl alcohol film surface with dirt and anti-blocking agents by washing the polyvinyl alcohol film with water, it also has the effect of preventing unevenness such as uneven coloring by swelling the polyvinyl alcohol film. is there. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching. The film can be stretched in an aqueous solution of boric acid or potassium iodide or in a water bath.

  As the transparent protective film provided on both surfaces of the polarizer and the material forming the transparent protective film, those excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like are preferable. For example, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, styrene such as polystyrene and acrylonitrile / styrene copolymer (AS resin) And polymers based on polycarbonate and polycarbonate. In addition, polyethylene, polypropylene, polyolefins having a cyclo or norbornene structure, polyolefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers , Polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy polymer, or the above Examples of the polymer that forms the transparent protective film include polymer blends. One or more kinds of arbitrary appropriate additives may be contained in the transparent protective film. Examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a mold release agent, an anti-coloring agent, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent. The content of the thermoplastic resin in the transparent protective film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. . When content of the said thermoplastic resin in a transparent protective film is 50 weight% or less, there exists a possibility that the high transparency etc. which a thermoplastic resin originally has cannot fully be expressed.

  As the transparent protective film of the present invention, at least one selected from cellulose resin (polymer), polycarbonate resin (polymer), cyclic polyolefin resin (cycloolefin or polyolefin having norbornene structure) and (meth) acrylic resin is used. Is preferred.

  Although the thickness of a transparent protective film can be determined suitably, generally it is about 1-500 micrometers from points, such as workability | operativity, such as intensity | strength and handleability, and thin layer property. 1-300 micrometers is especially preferable, and 5-200 micrometers is more preferable.

  The surface of the transparent protective film that adheres to the polarizer can be subjected to an easy adhesion treatment. Examples of the easy adhesion treatment include dry treatment such as plasma treatment and corona treatment, chemical treatment such as alkali treatment (saponification treatment), and coating treatment for forming an easy adhesive layer. Among these, a coating treatment or an alkali treatment for forming an easy-adhesive layer is preferable. For the formation of the easy-adhesive layer, various easy-adhesive materials such as polyol resin, polycarboxylic acid resin, and polyester resin can be used. The thickness of the easy-adhesive layer is usually about 0.001 to 10 μm, more preferably about 0.001 to 5 μm, and particularly preferably about 0.001 to 1 μm.

  The surface of the transparent protective film to which the polarizer is not adhered may be subjected to a hard coat layer, an antireflection treatment, an antisticking treatment, or a treatment for diffusion or antiglare.

  The antireflection layer, antisticking layer, diffusion layer, antiglare layer, and the like can be provided on the transparent protective film itself, or can be provided separately from the transparent protective film as an optical layer.

  Although it does not restrict | limit especially as an adhesive agent used for formation of the adhesive bond layer which bonds the said polarizer and a transparent protective film together, A water-system adhesive agent is suitable.

  Although it does not specifically limit as an aqueous adhesive, For example, a vinyl polymer type | system | group, a gelatin type, a vinyl type latex type, a polyurethane type, an isocyanate type, a polyester type, an epoxy type etc. can be illustrated. As the water-based adhesive, an adhesive containing a vinyl polymer is preferably used, and the vinyl polymer is preferably a polyvinyl alcohol resin. In particular, when a polyvinyl alcohol polymer film is used as the polarizer, it is preferable from the viewpoint of adhesiveness to use an adhesive containing a polyvinyl alcohol resin.

  Polyvinyl alcohol resin is polyvinyl alcohol obtained by saponifying polyvinyl acetate; a derivative thereof; a saponified product of a copolymer of vinyl acetate and a monomer having copolymerizability; Examples thereof include modified polyvinyl alcohols that have been converted into ethers, ethers, grafts, or phosphoric esters. Examples of the monomer include unsaturated carboxylic acids such as (anhydrous) maleic acid, fumaric acid, crotonic acid, itaconic acid, (meth) acrylic acid, and esters thereof; α-olefins such as ethylene and propylene, (meth) Examples include allyl sulfonic acid (soda), sulfonic acid soda (monoalkyl malate), disulfonic acid soda alkyl maleate, N-methylol acrylamide, acrylamide alkyl sulfonic acid alkali salt, N-vinyl pyrrolidone, N-vinyl pyrrolidone derivatives, and the like. . These polyvinyl alcohol resins can be used alone or in combination of two or more.

  The polyvinyl alcohol-based resin is not particularly limited, but from the viewpoint of adhesiveness, the average degree of polymerization is about 100 to 5000, preferably 1000 to 4000, the average saponification degree is about 85 to 100 mol%, preferably 90 to 100 mol%. It is.

  As the polyvinyl alcohol resin, for example, it is more preferable to use a polyvinyl alcohol resin having an acetoacetyl group from the viewpoint of improving durability. A polyvinyl alcohol-based resin containing an acetoacetyl group is obtained by reacting a polyvinyl alcohol-based resin with diketene by a known method. For example, a method in which a polyvinyl alcohol resin is dispersed in a solvent such as acetic acid and diketene is added thereto. A polyvinyl alcohol resin is previously dissolved in a solvent such as dimethylformamide or dioxane, and diketene is added thereto. And the like. Moreover, the method of making diketene gas or liquid diketene contact directly to polyvinyl alcohol is mentioned.

  The degree of acetoacetyl group modification of the polyvinyl alcohol-based resin containing an acetoacetyl group is not particularly limited as long as it is 0.1 mol% or more. If it is less than 0.1 mol%, the water resistance of the adhesive layer is insufficient and unsuitable. The degree of acetoacetyl group modification is preferably about 0.1 to 40 mol%, more preferably 1 to 20 mol%, and particularly preferably 2 to 7 mol%. When the acetoacetyl group modification degree exceeds 40 mol%, the effect of improving water resistance is small. The degree of acetoacetyl modification is a value measured by NMR.

  In addition, the adhesive layer formed from the water-based adhesive can be blended with a catalyst such as a crosslinking agent, other additives, and an acid, if necessary, in preparing the aqueous solution.

  As a crosslinking agent, what is used for the polyvinyl alcohol-type adhesive agent can be especially used without a restriction | limiting. A compound having at least two functional groups having reactivity with the polyvinyl alcohol resin can be used. For example, alkylene diamines having two alkylene groups and two amino groups such as ethylene diamine, triethylene diamine and hexamethylene diamine; tolylene diisocyanate, hydrogenated tolylene diisocyanate, trimethylolpropane tolylene diisocyanate adduct, triphenylmethane triisocyanate, methylene bis (4-phenylmethane triisocyanate), isophorone diisocyanate and isocyanates such as ketoxime block product or phenol block product thereof; ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin di or triglycidyl ether, 1,6- Hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, diglycy Epoxys such as ruaniline and diglycidylamine; monoaldehydes such as formaldehyde, acetaldehyde, propionaldehyde and butyraldehyde; dialdehydes such as glyoxal, malondialdehyde, succindialdehyde, glutardialdehyde, maleidialdehyde and phthaldialdehyde Amino-formaldehyde resins such as methylol urea, methylol melamine, alkylated methylol urea, alkylated methylol melamine, acetoguanamine, condensate of benzoguanamine and formaldehyde; zirconium acetate, zirconium nitrate, zirconium carbonate, zirconium hydroxide, acid Zirconium compounds such as zirconium chloride; metal glyoxylate (metals include, for example, lithium, sodium, potassium Alkaline earth metals such as magnesium, calcium, transition metals such as titanium, zirconium, chromium, manganese, iron, cobalt, nickel, copper, zinc, aluminum, etc.), glyoxylic acid amine salts (amines) Examples thereof include glyoxylates such as ammonia, monomethylamine, dimethylamine, trimethylamine, etc .; amino acids or sulfur-containing amino acids having one or more basic groups and one or more acidic groups; dimethoxy Acetal compounds such as ethanal, diethoxyethanal, dialkoxyethanal; and divalent metals such as sodium, potassium, magnesium, calcium, aluminum, iron, nickel, and salts of trivalent metals and oxides thereof . These can be used alone or in combination of two or more. Among these, it is preferable to use an amino acid or a sulfur-containing amino acid having one or more basic groups and one or more acidic groups. The basic group is preferably an amino group, and the acidic group is preferably a carboxyl group or a sulfo group. Examples of the amino acids include glycine, alanine, phenylalanine, valine, leucine, isoleucine, lysine, proline, serine, threonine, tryptophan, histidine, tyrosine, arginine, asparagine, aspartic acid, aspartame, glutamine, glutamic acid, and these amino acids. Examples include copolymers with (meth) acrylic acid. Examples of the sulfur-containing amino acid include methionine, cysteine, cystine, and taurine. Among these, it is particularly preferable to use a sulfur-containing amino acid having a sulfo group such as taurine. Moreover, as a crosslinking agent, coupling agents, such as a silane coupling agent and a titanium coupling agent, can be used.

  The amount of the crosslinking agent can be appropriately designed according to the type of polyvinyl alcohol resin, etc., but is usually about 0.1 to 50 parts by weight, preferably 0.2 to 100 parts by weight of the polyvinyl alcohol resin. About 30 parts by weight, more preferably 0.5 to 20 parts by weight. In such a range, good adhesiveness can be obtained.

  The adhesive may contain a metal compound filler. With the metal compound filler, the fluidity of the adhesive layer can be controlled, the film thickness can be stabilized, and a polarizing plate having a good appearance, uniform in-plane and no adhesive variation can be obtained.

  In the manufacturing method of the polarizing plate of this invention, it can manufacture by bonding together a transparent protective film and a polarizer using an adhesive agent. Specifically, the manufacturing method of the polarizing plate of the present invention includes a step of applying an adhesive to the polarizer and / or the transparent protective film, and a step of bonding the polarizer and the transparent protective film with the adhesive. Done. In addition, you may provide an undercoat layer, an easily bonding process layer, etc. between the transparent protective film or polarizer which applies an adhesive agent.

  Application | coating of the said adhesive agent may be performed to any of a transparent protective film and a polarizer, and may be performed to both. The adhesive is preferably applied so that the thickness of the dried adhesive layer formed between the polarizer and the transparent protective film is about 10 to 300 nm. The thickness of the adhesive layer is more preferably from 10 to 200 nm, particularly preferably from 20 to 150 nm, from the viewpoint of obtaining a uniform in-plane thickness and obtaining sufficient adhesive strength. When the thickness of the adhesive layer is less than 10 nm, the adhesive strength is not sufficient, and when it exceeds 300 nm, the optical reliability and moisture resistance tend to be lowered.

  The adhesive coating operation is not particularly limited, and various means such as a gravure coating method, a die coating method, a roll coating method, a spray coating method, and a dip coating method can be adopted, but the adhesive can be applied uniformly. A gravure coating method and a die coating method are preferred.

  The method of adjusting the thickness of the adhesive layer is not particularly limited, and examples thereof include a method of adjusting the solid content concentration of the adhesive solution and an adhesive application device. The method for measuring the thickness of the adhesive layer is not particularly limited, but cross-sectional observation measurement using SEM (Scanning Electron Microscopy) or TEM (Transmission Electron Microscopy) is preferably used. The application operation of the adhesive is not particularly limited, and various means such as a roll method, a spray method, and an immersion method can be employed.

  After applying the adhesive, the polarizer and the transparent protective film are bonded together with a roll laminator or the like. After bonding, a drying process is performed. The drying temperature is about 5 to 150 ° C., preferably 30 to 120 ° C., and the drying time is 120 seconds or more, preferably 300 seconds or more.

  The polarizing plate obtained by the production method of the present invention can be used as an optical film laminated with another optical layer in practical use. The optical layer is not particularly limited. For example, for forming a liquid crystal display device such as a reflection plate, a semi-transmission plate, a retardation plate (including wavelength plates such as 1/2 and 1/4), and a viewing angle compensation film. One or two or more optical layers that may be used can be used. In particular, a reflective polarizing plate or a semi-transmissive polarizing plate in which a polarizing plate or a semi-transmissive reflecting plate is further laminated on the polarizing plate of the present invention, an elliptical polarizing plate or a circularly polarizing plate in which a retardation plate is further laminated on the polarizing plate. A wide viewing angle polarizing plate obtained by further laminating a viewing angle compensation film on a plate or a polarizing plate, or a polarizing plate obtained by further laminating a brightness enhancement film on the polarizing plate is preferable.

  The polarizing plate or the optical film of the present invention can be preferably used for forming various devices such as a liquid crystal display device. The liquid crystal display device can be formed according to the conventional method. That is, a liquid crystal display device is generally formed by appropriately assembling components such as a liquid crystal cell, a polarizing plate or an optical film, and an illumination system as necessary, and incorporating a drive circuit. There is no limitation in particular except the point which uses the polarizing plate or optical film by invention, According to the past. As the liquid crystal cell, any type such as a TN type, an STN type, or a π type can be used.

  An appropriate liquid crystal display device such as a liquid crystal display device in which a polarizing plate or an optical film is disposed on one side or both sides of a liquid crystal cell, or a backlight or a reflector used in an illumination system can be formed. In that case, the polarizing plate or optical film by this invention can be installed in the one side or both sides of a liquid crystal cell. When providing a polarizing plate or an optical film on both sides, they may be the same or different. Further, when forming a liquid crystal display device, for example, a single layer or a suitable part such as a diffusing plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusing plate, a backlight, etc. Two or more layers can be arranged.

  The present invention will be described more specifically with reference to the following examples and comparative examples. However, the present invention is not limited to these examples and comparative examples.

<Measurement of dimensional change rate>
The transparent protective film was cut out to 10 cm × 10 cm, and 60 ° C., 90% R.D. H. The dimension of what was put into the environment for 1 hour is a (cm). Then, the dimension of what was put in an environment of 80 ° C. for 24 hours was defined as b (cm). And the dimensional change rate was computed with the following formula.
Dimensional change rate (%) = {(ab) / a} × 100
In addition, the dimensional change rate evaluated the dimensional change rate which hits the width direction, when using for a polarizing plate.

<Transparent protective film>
The transparent protective film shown below was used.
The width of each transparent protective film is 1330 mm.
1: Cyclic olefin resin film having a thickness of 25 μm (Arton) manufactured by JSR; Dimensional change rate = 0.0763
2: Cyclic olefin resin film having a thickness of 35 μm (manufactured by JSR, Arton); dimensional change rate = 0.0515
3: Triacetyl cellulose film having a thickness of 40 μm (Konica Corp., KC4UYW); dimensional change rate = 0.201

<Production of polarizer>
Using a polyvinyl alcohol film having a thickness of 75 μm (manufactured by Kuraray Co., Ltd .: VF-PS7500, width 1000 mm or width 2600 mm), the film was stretched to 2.5 times while being immersed in pure water at 30 ° C. for 60 seconds, Dyeing is performed for 45 seconds in an iodine aqueous solution (weight ratio: pure water / iodine (I) / potassium iodide (KI) = 100 / 0.01 / 1) at 30 ° C., and the draw ratio is 4 wt% boric acid aqueous solution. The film was stretched to 5.8 times, immersed in pure water for 10 seconds, and then dried at 60 ° C. for 3 minutes while maintaining the film tension to obtain a polarizer. This polarizer had a thickness of 25 μm and a width of 446 mm or a width of 1160 mm.

<Preparation of adhesive>
100 parts by weight of polyvinyl alcohol resin (manufactured by Nippon Synthetic Chemical Industry Co., Ltd .: Ecomati) and 35 parts by weight of a crosslinking agent (manufactured by Dainippon Ink Chemical Co., Ltd .: Watersol) are dissolved in 3760 parts by weight of pure water and bonded. An aqueous agent solution was prepared.

Example 1
(Preparation of polarizing plate)
The transparent protective film 1 having a width of 1330 mm (applied to one side of a 25 μm-thick cyclic olefin-based resin film so that the adhesive layer after drying the adhesive solution has a thickness of 80 nm and being transparent with an adhesive) The protective film 1 was obtained, on the other hand, on one side of the transparent protective film 2 having a width of 1330 mm (triacetyl cellulose film having a thickness of 40 μm) so that the adhesive layer after drying the aqueous adhesive solution had a thickness of 80 nm. Application was performed to obtain a transparent protective film 2 with an adhesive, and the adhesive was applied to the transparent protective films 1 and 2 with an adhesive, and the width of the applied adhesive was 1160 mm. It performed so that the location which should not apply | coat an adhesive agent may become substantially the same on both sides of each transparent protective film 1 and 2 so that it may become the same as width | variety. The transparent protective films 1 and 2 with the adhesive are present on both sides of the polarizer having a width of 1160 mm from the end portions on both sides of the polarizer toward the outside in the width direction of the polarizer. At the same time, they were bonded together with a roll machine so that the width w of the adhesive was 0 mm, followed by a drying process at 80 ° C. for 10 minutes to produce a polarizing plate. The adhesive width w in the width direction is all 0 mm, which relates to the embodiment of FIG.

Examples 2-12 and Comparative Examples 1-12
In Example 1, as shown in Table 1, the width of the polarizer, the type of the first transparent protective film, the type of the second transparent protective film, or the width w of the adhesive existing from the end of the polarizer toward the outside ( A polarizing plate was produced in the same manner as in Example 1 except that the widths on both sides were set to be the same. In addition, the obtained polarizing plate concerns on the aspect of FIG. 2 when the adhesive width w of the width direction of a polarizing plate is 0 mm, and relates to the aspect of FIG. 1 in the case other than that. In the embodiment of FIG. 1, the adhesive is applied to the transparent protective films 1 and 2 with the adhesive in consideration of the width w of the adhesive existing from the end of the polarizer toward the outside. The width of the agent was controlled.

  In the above examples and comparative examples, the following evaluations were performed when producing polarizing plates. The evaluation results are shown in Table 1.

(Strike)
In the production line of the polarizing plate, the traveling property of the obtained polarizing plate was verified according to the following criteria. ○: Driving is possible. ×: Driving is not possible.

P Polarizer T1 First transparent protective film T2 Second transparent protective film a1, a2, a3 Adhesive

Claims (2)

This is a method for producing a long polarizing plate by laminating a first transparent protective film via an adhesive on one surface of a polarizer and a second transparent protective film via an adhesive on the other surface. And
The first transparent protective film and the second transparent protective film have a dimensional change rate (%) of the first transparent protective film of L1, and a dimensional change rate of the second transparent protective film of L2 (%). The absolute value of the difference in dimensional change rate (L1-L2) satisfies 0.10 or more,
And the width | variety of a polarizer is below the width | variety of a 1st transparent protective film and a 2nd transparent protective film, Comprising: The adhesive which exists toward the outer side from the edge part of the both sides of a polarizer in the width direction of a polarizer A method for producing a polarizing plate, wherein the width w (mm) of the agent satisfies 0 ≦ w ≦ 75.   The method for producing a polarizing plate according to claim 1, wherein the width of the first transparent protective film is different from the width of the second transparent protective film.