TWI564599B - Polishing plate manufacturing method - Google Patents

Description

Method for manufacturing polarizing plate

The present invention relates to a method of manufacturing a polarizing plate. The polarizing plate obtained by the production method of the present invention can be formed into an image display device such as a liquid crystal display device, an organic EL display device, or a PDP, either alone or in the form of an optical film formed by laminating it.

In the liquid crystal display device, it is indispensable to arrange a polarizing element on both sides of the glass substrate on which the surface of the liquid crystal panel is formed due to the image forming method. The polarizing element is usually formed by dyeing a polyvinyl alcohol-based film with a dichroic material such as iodine, and then crosslinking it with a crosslinking agent to carry out uniaxial stretching. Further, since the polyvinyl alcohol-based film is a hydrophilic polymer, it is very easily deformed particularly under humidified conditions. Further, since the mechanical strength of the film itself is weak, there is a problem that the film is broken. For this reason, the polarizing plate in which the strength is enhanced by bonding a transparent protective film such as triacetyl cellulose or the like to a transparent protective film such as a polyvinyl alcohol-based adhesive or the like on both sides or a single side of the polarizing element has been used.

As a method of manufacturing a usual polarizing plate, it is known that a water-washed transparent protective film is disposed on both surfaces of a polarizing element, and an adhesive is interposed between layers of the polarizing element and the transparent protective film to pass between a pair of rolls, and then used The method of drying the oven.

The transparent protective film is prone to dimensional changes during the drying stage. However, as described above, in the method of manufacturing a usual polarizing plate, a drying step is performed after bonding a transparent protective film to a polarizing element using an adhesive. When the transparent protective film or the like changes in size during the drying step and the polarizing plate is curled, there is a problem that the mobility of the polarizing plate is deteriorated in the manufacturing process of the continuous polarizing plate. Especially for the transparent protective film attached to both sides of the polarizing element When the dimensional change rate is different, curling is likely to occur, and work efficiency is lowered.

As a method of suppressing the curl of the polarizing plate, for example, a method of reducing the thickness of the transparent protective film has been proposed (Patent Document 1). In addition, when a polarizing plate is manufactured, a single transparent protective film is bonded to one surface of a polarizing element, and another transparent protective film is bonded to the remaining single surface (Patent Document 2).

[Previous Technical Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2001-235625

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2004-117482

The polarizing plates obtained in Patent Documents 1 and 2 have an effect of suppressing curling, but the structure of the polarizing plate itself does not change, and the viewpoint of suppressing curling from the end portion of the polarizing plate has not been studied.

An object of the present invention is to provide a method for producing a polarizing plate, which is a method of manufacturing a polarizing plate by bonding a first transparent protective film to one surface of a polarizing element via an adhesive, and bonding a second transparent protective film to another surface via an adhesive. Even when the difference in dimensional change ratio between the first transparent protective film and the second transparent protective film is large, curling can be suppressed.

The inventors of the present invention have repeatedly studied the above problems, and as a result, have found that the above object can be attained by the method for producing a polarizing plate described below, and the present invention has been completed.

In other words, the present invention relates to a method for producing a polarizing plate, wherein the first transparent protective film is bonded to one surface of the polarizing element via an adhesive, and the second transparent protective film is bonded to the other surface via an adhesive. a method of manufacturing a long polarizing plate, In the first transparent protective film and the second transparent protective film, when the dimensional change ratio (%) of the first transparent protective film is L1 and the dimensional change ratio of the second transparent protective film is L2 (%), the dimensional change rate The absolute value of the difference (L1-L2) satisfies 0.10 or more. Further, the width of the polarizing element is equal to or less than the width of the first transparent protective film and the second transparent protective film, and the width w (mm) of the adhesive existing from the end portions on both sides of the polarizing element toward the outside in the width direction of the polarizing element satisfies 0≦w≦75.

In the method for producing a polarizing plate, the first transparent protective film and the second transparent protective film may have different widths.

In the method for producing a polarizing plate of the present invention, the difference in dimensional change ratio between the transparent protective films bonded to both surfaces of the polarizing element is large, and in the conventional manufacturing method, curling tends to occur at the end portion of the polarizing plate. It is known that the reason for the occurrence of the curl is as follows: when a transparent protective film having a width wider than that of the polarizing element is bonded to the polarizing element by an adhesive, the end portion of the obtained polarizing plate is not subjected to the adhesive by the polarizing element. Constrain the transparent protective film.

In the method for producing a polarizing plate of the present invention, the width of the polarizing element used is less than the width of the transparent protective film, but the adhesive is applied in such a manner that the end of the polarizing element is oriented in the width direction of the polarizing element. The outer side does not have an adhesive or has an adhesive below a certain width. In the method for producing a polarizing plate of the present invention, the transparent protective film disposed on both surfaces of the polarizing element is not controlled by the adhesive member via the polarizing element on the outer side of the end portion in the width direction of the polarizing element. It is smaller. As a result, in the central portion of the polarizing plate, the polarizing element serves as a support to suppress curling, and the width of the adhesive which causes curling outside the end portion of the polarizing element in the width direction is controlled to be small. Therefore, it is considered that even when a transparent protective film having a large difference in dimensional change ratio is used on both surfaces of the polarizing element, curling at the end portion of the polarizing plate can be suppressed.

Further, in the method for producing a polarizing plate of the present invention, by using a transparent protective film having a different width as a transparent protective film provided on both surfaces of the polarizing element, curling at the end portion in the width direction of the polarizing plate can be effectively suppressed. . When the width of the transparent protective film used on both sides of the polarizing element is different, the transparent protective film having a wide width can be freely The expansion and contraction in the width direction can effectively suppress the curl generated at the end portion in the width direction of the polarizing plate.

According to the method for producing a polarizing plate of the present invention, even when the transparent protective film provided on both surfaces of the polarizing element is different in dimensional change rate, curling can be suppressed in the production stage of the polarizing plate, and the polarizing plate can be stably produced. Thereby, an image display device such as a liquid crystal display device (LCD) or an electroluminescence display device (ELD) having a high degree of freedom of selection of a transparent protective film and a wide range of optical design, high resolution and high contrast can be realized. .

A1, a2, a3‧‧‧ adhesive

P‧‧‧ Polarized components

T1‧‧‧1st transparent protective film

T2‧‧‧2nd transparent protective film

W _t1 ‧‧‧The width of the first transparent protective film T1

W _t2 ‧‧‧The width of the second transparent protective film T2

W _p ‧‧‧width of polarizing element

W1‧‧‧The width of the adhesive (a3)

W2‧‧‧The width of the adhesive (a3)

Fig. 1 is a cross-sectional view showing an example of an embodiment of a method for producing a polarizing plate of the present invention.

Fig. 2 is a cross-sectional view showing an example of another embodiment of the method for producing a polarizing plate of the present invention.

Fig. 3 is a cross-sectional view showing an example of another embodiment of the method for producing a polarizing plate of the present invention.

Fig. 4 is a cross-sectional view showing an example of another embodiment of the method for producing a polarizing plate of the present invention.

Hereinafter, an embodiment of a method for producing a polarizing plate of the present invention will be described below with reference to the drawings. 1 to 4 are cross-sectional views showing an example of a polarizing plate of the manufacturing method of the present invention. As shown in FIG. 1 to FIG. 4, in the method of manufacturing a polarizing plate of the present invention, the first transparent protective film T1 and the second transparent protective film T2 are provided on both surfaces of the polarizing element P via the adhesives (a1, a2). The width W _p of the polarizing element P is _{equal to} or smaller than the width W _{t1 of the} first transparent protective film T1 and the width W _{t2 of the} second transparent protective film T2. The polarizing plates of Figs. 1 and 2 show the case where the widths W _t1 and W _{t2 are the} same. The polarizing plates of Figs. 3 and 4 show the above-described width W _t1 > W _t2 .

In addition, the polarizing plates described in FIG. 1 and FIG. 3 are on both sides in the width direction of the polarizing element, and the first transparent protective film T1 and the second transparent protective film T2 are directed outward without passing through the polarizing element P and are made of an adhesive (a3). ) The situation of fit. In addition, the width W _p of the polarizing plate-based polarizing element described in FIGS. 2 and 4 coincides with the width of the adhesives ( a1 and a2 ), and the adhesive agent does not have an adhesive agent on the outer side of the end portion in the width direction of the polarizing element P.

In the polarizing plate of FIGS. 1 and 3, in the width direction of the polarizing element P, an adhesive (a3) is present from the end portions on both sides of the polarizing element P toward the outside. The adhesive (a3) bonds the first transparent protective film T1 and the second transparent protective film T2. The width w of the above-mentioned adhesive (a3) existing outside the end portions on both sides of the polarizing element P is represented by w1 and w2, respectively. The widths w1 and w2 of the above-mentioned adhesive (a3) may be the same or different.

In the polarizing plate shown in FIGS. 1 and 3, when the width w (w1, w2) of the adhesive (a3) is too wide, the polarizing plate is not well moved. The width w (mm) of the above-mentioned adhesive (a3) is controlled to be 0 ≦ w ≦ 75. The width w of the above-mentioned adhesive (a3) is preferably 10 ≦ w ≦ 75 from the viewpoint of the production process, and is preferably 10 ≦ w ≦ 60 from the viewpoint of further suppressing curl. In the case where w=0 in the polarizing plate described in FIGS. 1 and 3, the width W _{p of the} polarizing element coincides with the width of the adhesives (a1 and a2), and corresponds to the polarizing plates described in FIGS. 2 and 4 .

The width W _p (mm) of the above polarizing element is usually preferably from 300 to 2000 mm. On the other hand, the width W _t1 (mm) of the first transparent protective film T1 and the width W _t2 (mm) of the second transparent protective film T2 are _{equal to} or larger than the width W _p (mm) of the polarizing element P. It is generally preferred that the first transparent protective film and the second transparent protective film have a width of 350 to 2300 mm.

Further, the width W _t1 (mm) of the first transparent protective film T1 and the width W _t2 (mm) of the second transparent protective film T2 are longer than the width W _{p of the} polarizing element P in the polarizing plate shown in FIG. 1 . The length obtained by adding the width w of the adhesive (a3) is longer than the width W _p (mm) of the polarizing element P in the polarizing plate shown in FIG. 2 .

Further, the method for producing a polarizing plate of the present invention can be effectively used in the following cases. In other words, in the first transparent protective film T1 and the second transparent protective film T2, the dimensional change ratio (%) of the first transparent protective film T1 is L1, and the dimensional change rate (%) of the second transparent protective film T2 is set. When it is set to L2, the absolute value of the dimensional change rate difference (L1-L2) is 0.10 or more, that is, the case where the dimensional change rate is large. Further, from the viewpoint of mobility, the absolute value of the dimensional change rate difference (L1 - L2) is preferably 0.15 or less. Further, the selection of the first transparent protective film T1 and the second transparent protective film T2 whose absolute value of the dimensional change rate difference (L1 - L2) is 0.10 or more can be adjusted by using different materials and different thicknesses.

Further, in FIG. 3, FIG. 4, the method for manufacturing a polarizing plate according to the present invention, the transparent protective film may be a width W _t1 of the first transparent protective film different from those of T1 and the second transparent protective film width W _t1 of T2. By using a transparent protective film having a different width, it is possible to suppress curling of the polarizing plate even when a transparent protective film having a different dimensional change rate is used. The width W _t1 (mm) of the first transparent protective film T1 is longer than the width W _p (mm) of the polarizing element P and the width w of the adhesive (a3) in the polarizing plate shown in FIG. In the polarizing plate described in 4, it is longer than the width W _p (mm) of the polarizing element P.

As shown in FIGS. 1 to 4, the width W _t of at least one of the transparent protective films is longer than the length obtained by adding the width w of the polarizing element W _p and the adhesive (a3), thereby effectively suppressing the polarization. It is preferable that the end portion in the width direction of the sheet is curled.

In the polarizing plate of the above-mentioned FIG. 3 and FIG. 4, when the width of the first transparent protective film T1 is wider than that of the second transparent protective film T2, the dimensional change rate (%) of the first transparent protective film is larger than that of the second transparent protective film. The film T2, that is, a material satisfying L1 > L2 is effective in suppressing curl.

Hereinafter, the polarizing element, the transparent protective film, and the adhesive used in the polarizing plate of the present invention will be described.

The polarizing element is not particularly limited, and various polarizing elements can be used. Examples of the polarizing element include adsorption of iodine or a dichroic dye on a hydrophilic polymer film such as a polyvinyl alcohol film, a partially methylalized polyvinyl alcohol film, or an ethylene-vinyl acetate copolymer partially saponified film. A dichroic material is obtained by uniaxially stretching, a dehydration treatment of polyvinyl alcohol, a polyene-based alignment film such as a dehydrochlorination treatment of polyvinyl chloride, or the like. Among these, a polarizing element including a polyvinyl alcohol-based film and a dichroic substance such as iodine is preferable. The thickness of the polarizing element is not particularly limited and is usually about 5 to 80 μm. The thickness of the polarizing element is preferably 15 to 35 μm.

A polarizing element obtained by dyeing a polyvinyl alcohol-based film with iodine and uniaxially stretching can be produced, for example, by immersing polyvinyl alcohol in an aqueous solution of iodine for dyeing and extending to the original length of 3 ~7 times. It may also be immersed in an aqueous solution of boric acid or potassium iodide as needed. Further, the polyvinyl alcohol-based film may be immersed in water and washed with water before dyeing. By washing the polyvinyl alcohol-based film with water, the stain and the anti-adhesive agent on the surface of the polyvinyl alcohol-based film can be washed, and in addition, the polyvinyl alcohol-based film can be swollen to prevent uneven dyeing. Even effect. The extension may be carried out after dyeing with iodine, or may be extended while dyeing, or may be dyed with iodine after stretching. It can also be extended in an aqueous solution of boric acid or potassium iodide or in a water bath.

The transparent protective film provided on both surfaces of the polarizing element and the material forming the transparent protective film are preferably excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, and the like. For example, a polyester-based polymer such as polyethylene terephthalate or polyethylene naphthalate; a cellulose-based polymer such as diethyl fluorenyl cellulose or triethyl fluorenyl cellulose; Acrylic polymer such as methyl acrylate; styrene polymer such as polystyrene or acrylonitrile-styrene copolymer (AS resin); polycarbonate polymer. Further, examples of the polymer forming the transparent protective film may be mentioned as follows: polyethylene, polypropylene, ring system or have a drop A polyolefin having an olefin structure, such as a polyolefin-based polymer of an ethylene-propylene copolymer, a vinyl chloride-based polymer, a guanamine-based polymer such as nylon or an aromatic polyamine, a ruthenium-based polymer, or a ruthenium-based polymer , polyether oxime polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymerization A polyoxymethylene-based polymer, an epoxy-based polymer, or a blend of the above polymers. The transparent protective film may contain one or more optional additives. Examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a mold release agent, a coloring preventive agent, a flame retardant, a nucleating agent, an antistatic agent, a pigment, a colorant, and the like. The content of the above thermoplastic resin in the transparent protective film is preferably from 50 to 100% by weight, more preferably from 50 to 99% by weight, still more preferably from 60 to 98% by weight, particularly preferably from 70 to 97% by weight. When the content of the thermoplastic resin in the transparent protective film is 50% by weight or less, the high transparency and the like inherent in the thermoplastic resin may not be sufficiently exhibited.

As the transparent protective film of the present invention, it is preferred to use at least one selected from the group consisting of cellulose resin (polymer), polycarbonate resin (polymer), cyclic polyolefin resin (ring system or drop Polyolefin structure and (meth)acrylic resin.

The thickness of the transparent protective film can be appropriately determined, and is usually about 1 to 500 μm from the viewpoints of workability such as strength and workability, and thin layer properties. It is preferably from 1 to 300 μm, more preferably from 5 to 200 μm.

The subsequent processing of the transparent protective film and the polarizing element can be carried out. Examples of the easy-to-treat treatment include a dry treatment such as a plasma treatment or a corona treatment; a chemical treatment such as an alkali treatment (saponification treatment); and a coating treatment for forming an easy-adhesion layer. Among these, it is preferred to form a coating treatment or an alkali treatment of an easy-adhesion layer. Various easy-adhesive materials such as a polyol resin, a polycarboxylic acid resin, and a polyester resin can be used to form the easy-adhesive layer. Further, the thickness of the easy-adhesive layer is preferably about 0.001 to 10 μm, more preferably about 0.001 to 5 μm, and particularly preferably about 0.001 to 1 μm.

For the surface of the transparent protective film which is not attached to the polarizing element, a hard coat layer or an anti-reflection treatment may be applied to treat the adhesion, diffusion or anti-glare.

Further, the antireflection layer, the anti-blocking layer, the diffusion layer, the antiglare layer, and the like may be provided as the transparent protective film itself, or may be provided separately from the transparent protective film as another optical layer.

The adhesive used for forming the adhesive layer to which the polarizing element and the transparent protective film are bonded is not particularly limited, and is preferably a water-based adhesive.

The water-based adhesive is not particularly limited, and examples thereof include a vinyl polymer, a gelatin, a vinyl latex, a polyurethane, an isocyanate, a polyester, and an epoxy. As the water-based adhesive, an adhesive containing a vinyl polymer or the like is preferably used, and as the vinyl polymer, a polyvinyl alcohol-based resin is preferable. In particular, when a polyvinyl alcohol-based polymer film is used as the polarizing element, it is preferable to use an adhesive containing a polyvinyl alcohol-based resin from the viewpoint of adhesion.

Examples of the polyvinyl alcohol-based resin include a polyvinyl alcohol obtained by saponifying polyvinyl acetate; a derivative thereof; and a saponified product of a copolymer of vinyl acetate and a monomer having copolymerizability; A modified polyvinyl alcohol obtained by acetalization, urethanization, etherification, grafting, or phosphation. Examples of the monomer include unsaturated carboxylic acids such as maleic acid (anhydride), fumaric acid, crotonic acid, itaconic acid, and (meth)acrylic acid, and esters thereof; ethylene, propylene, and the like. Α-olefin, (meth)allylsulfonic acid (sodium), sodium sulfonate (single alkyl maleate), sodium disulfonate alkyl maleate, N-methylol Acrylamide, acrylamide alkylsulfonate alkali metal salt, N-vinylpyrrolidone, N-vinylpyrrolidone derivative, and the like. These polyvinyl alcohol-based resins may be used alone or in combination of two or more.

The polyvinyl alcohol-based resin is not particularly limited, and the average degree of polymerization is from about 100 to 5,000, preferably from 1,000 to 4,000, and the average degree of saponification is from about 85 to 100 mol%, preferably from the viewpoint of adhesion. It is 90~100% by mole.

As the polyvinyl alcohol-based resin, for example, a polyvinyl alcohol-based resin having an ethyl acetonitrile group is more preferable from the viewpoint of improving durability. The polyvinyl alcohol-based resin containing an ethyl acetonitrile group can be obtained by reacting a polyvinyl alcohol-based resin with diketene by a known method. For example, a method of dispersing a polyvinyl alcohol-based resin in a solvent such as acetic acid and adding a diketene thereto; and dissolving the polyvinyl alcohol-based resin in dimethylformamide or two in advance may be mentioned. A method of adding a diketene to a solvent such as an alkane or the like. Further, a method of directly contacting the diketene gas or the liquid diketene with the polyvinyl alcohol can be mentioned.

The degree of modification of the ethyl acetonitrile group of the polyvinyl alcohol-based resin containing an ethyl acetonitrile group is not particularly limited as long as it is 0.1 mol% or more. When the amount is less than 0.1 mol%, the water resistance of the adhesive layer is insufficient, which is not suitable. The degree of modification of the acetamidine group is preferably from about 0.1 to 40 mol%, more preferably from 1 to 20 mol%, and particularly preferably from 2 to 7 mol%. When the degree of modification of the ethyl acetonitrile group exceeds 40 mol%, the effect of improving the water resistance is small. The acetamidine modification degree is a value measured by NMR (nuclear magnetic resonance).

Further, the adhesive layer formed of the above aqueous binder may be prepared by mixing a crosslinking agent or other additives, an acid or the like as needed in the preparation of an aqueous solution thereof.

As the crosslinking agent, a user who has been using a polyvinyl alcohol-based adhesive agent without any particular limitation can be used. A compound containing at least two functional groups reactive with the above polyvinyl alcohol-based resin can be used. For example, ethylene diamines having an alkyl group and two amine groups such as ethylenediamine, triethylenediamine, and hexamethylenediamine; toluene diisocyanate, hydrogenated toluene diisocyanate, and trimethylol group; Propane toluene diisocyanate adduct, triphenylmethane triisocyanate, methylene bis(4-phenylmethane triisocyanate), isophorone diisocyanate, and the ketone oxime end cap or phenol end capping Isocyanates; ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol di or triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, Epoxy such as diglycidyl aniline or diglycidylamine; monoaldehydes such as formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde; glyoxal, malondialdehyde, succinaldehyde, glutaraldehyde, butene Dialdehydes such as dialdehyde and phthalaldehyde; methylol urea, methylol melamine, alkylated methylol urea, alkylated methylol melamine, methyl decylamine, benzoguanamine and formaldehyde Amine-formaldehyde resin such as condensate; zirconium compound such as zirconium acetate, zirconium nitrate, zirconium carbonate, zirconium hydroxide or zirconium oxychloride Glycolic acid metal salt (as a metal, for example, an alkali metal such as lithium, sodium or potassium, an alkaline earth metal such as magnesium or calcium, a transition metal such as titanium, zirconium, chromium, manganese, iron, cobalt, nickel or copper, zinc, Aluminum, etc.), glyoxylate amine salt (as an amine, for example, can be listed Glyoxylate such as ammonia, monomethylamine, dimethylamine, trimethylamine, etc.; amino acid or thiol-containing acid having one or more basic groups and one or more acidic groups; An acetal compound such as acetaldehyde, diethoxy acetaldehyde or dialkoxy acetaldehyde; further examples thereof include divalent metals such as sodium, potassium, magnesium, calcium, aluminum, iron, and nickel, or salts of trivalent metals; Its oxide. These compounds may be used alone or in combination of two or more. Among these, an amino acid or a sulfur-containing amino acid having one or more basic groups and one or more acidic groups is preferably used. As the basic group, an amine group is preferred, and as the acidic group, a carboxyl group or a sulfo group is preferred. Examples of the amino acid include glycine, alanine, phenylalanine, valine, leucine, isoleucine, lysine, lysine, serine, and sulphite. , tryptophan, histidine, tyrosine, arginine, aspartame, aspartic acid, aspartame, glutamate, glutamic acid, and the amino acid a copolymer of acrylic acid or the like. Examples of the sulfur-containing amino acid include methionine, cysteine, cystine, and taurine. Among these, a sulfur-containing amino acid having a sulfo group such as taurine is particularly preferred. Further, as the crosslinking agent, a coupling agent such as a decane coupling agent or a titanium coupling agent can be used.

The amount of the above-mentioned crosslinking agent can be appropriately designed according to the type of the polyvinyl alcohol-based resin, etc., and is usually about 0.1 to 50 parts by weight, preferably about 0.2 to 30 parts by weight, per 100 parts by weight of the polyvinyl alcohol-based resin. Further preferably, it is 0.5 to 20 parts by weight. Good adhesion can be obtained within this range.

Further, the above-mentioned adhesive may contain a metal compound filler. The fluidity of the adhesive layer can be controlled by the metal compound filler to stabilize the film thickness, and a polarizing plate having a good appearance, uniform in-plane, and unevenness in adhesion can be obtained.

In the method for producing a polarizing plate of the present invention, the transparent protective film and the polarizing element can be bonded together by using an adhesive. Specifically, the method for producing a polarizing plate of the present invention can be carried out by performing the steps of: applying an adhesive to a polarizing element and/or a transparent protective film; and using a bonding agent to form a polarizing element and a transparent protective film. The step of fitting. Furthermore, an undercoat layer or an easy layer may be provided between the transparent protective film or the polarizing element to which the adhesive is applied. Then the layer is processed.

The application of the above-mentioned adhesive can be carried out on either the transparent protective film or the polarizing element, or both. The application of the above-mentioned adhesive is preferably carried out so that the thickness of the dried adhesive layer formed between the polarizing element and the transparent protective film is about 10 to 300 nm. The thickness of the adhesive layer is 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 a sufficient adhesion. When the thickness of the adhesive layer is less than 10 nm, the bonding force is insufficient, and when it exceeds 300 nm, optical reliability and moisture resistance tend to be lowered.

The coating operation of the above-mentioned adhesive is not particularly limited, and various methods such as gravure coating, die coating, roll coating, spray coating, and dip coating may be employed, and the adhesive may be uniformly applied. From the viewpoint of the above, a gravure coating method or a die coating method is preferred.

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

After the application of the adhesive, the polarizing element is bonded to the transparent protective film by a roll bonding machine or the like. The drying step is carried out after the bonding. 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 manufacturing method of the present invention can be used as an optical film laminated with other optical layers in practical use. The optical layer is not particularly limited, and for example, a reflector or a semi-transmissive plate, a retardation plate (including a 1/2 or 1/4 wave plate), a viewing angle compensation film, or the like may be used to form a liquid crystal display device or the like. The optical layer is used in one layer or two or more layers. Particularly preferably, a reflective polarizing plate or a semi-transmissive polarizing plate in which a reflecting plate or a semi-transmissive reflecting plate is further laminated on the polarizing plate of the present invention, and an ellipsoid formed by further laminating a phase difference plate on the polarizing plate A circular polarizing plate or a circular polarizing plate, a wide viewing angle polarizing plate in which a viewing angle compensation film is further laminated on a polarizing plate, or a polarizing plate in which a brightness improving film is further laminated on a polarizing plate.

The polarizing plate or the optical film of the present invention can be preferably used in the formation of various devices such as a liquid crystal display device. The formation of the liquid crystal display device can be carried out in accordance with the prior methods. In other words, the liquid crystal display device is usually formed by appropriately assembling a liquid crystal cell, a polarizing plate, an optical film, and an optional illumination system, and the like, and assembling the driving circuit or the like. In the present invention, the polarizing plate of the present invention is used. Other than the aspect of the optical film, the other is not particularly limited and may be based on the previous method. As the liquid crystal cell, any type of liquid crystal cell such as a TN (twisted nematic) type or an STN (super twisted nematic) type or a π type can be used.

A suitable 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 device using a backlight or a reflecting plate in an illumination system can be formed. At this time, the polarizing plate or the optical film of the present invention may be disposed on one side or both sides of the liquid crystal cell. When a polarizing plate or an optical film is provided on both sides, the same may be the same or different. Further, when forming a liquid crystal display device, one or two or more layers such as a diffusion plate, an antiglare layer, an antireflection film, a protective plate, a tantalum array, a lens array sheet, a light diffusing plate, and a backlight may be disposed at appropriate positions. Wait for the appropriate parts.

[Examples]

Hereinafter, the present invention will be specifically described by way of Examples and Comparative Examples, but the present invention is not limited by the Examples and Comparative Examples.

<Measurement of dimensional change rate>

The transparent protective film was cut into 10 cm × 10 cm, and the size of the protective film after being placed in an environment of 60 ° C and 90% R.H. for 1 hour was set to a (cm). Then, the size of the protective film after being placed in an environment of 80 ° C for 24 hours was set to b (cm). Then, the dimensional change rate was calculated by the following calculation formula.

Dimensional change rate (%) = {(a-b) / a} × 100

Further, regarding the dimensional change rate, the dimensional change rate in the width direction when used for the polarizing plate was evaluated.

<Transparent protective film>

As the transparent protective film, the following ones were used.

The width of the transparent protective film is 1330 mm.

1: Cylindrical olefin resin film having a thickness of 25 μm (manufactured by JSR Corporation: ARTON); dimensional change rate = 0.0763

2: a cyclic olefin resin film having a thickness of 35 μm (manufactured by JSR Corporation: ARTON); dimensional change rate = 0.0515

3: Triethylenesulfonated cellulose film having a thickness of 40 μm (manufactured by KONICA: KC4UYW); dimensional change rate=0.2011

<Production of polarizing element>

A polyvinyl alcohol film (manufactured by KURARAY Co., Ltd.: VF-PS7500, width: 1000 mm or width: 2,600 mm) having a thickness of 75 μm was used while being immersed in pure water at 30 ° C for 60 seconds until the stretching ratio was 2.5 times. It was dyed in an aqueous solution of iodine at 30 ° C (weight ratio: pure water / iodine (I) / potassium iodide (KI) = 100 / 0.01 / 1) for 45 seconds, and extended in a 4% by weight aqueous solution of boric acid at a stretching ratio of 5.8 times. After immersing in pure water for 10 seconds, it was dried at 60 ° C for 3 minutes while maintaining the tension of the film to obtain a polarizing element. The polarizing element has a thickness of 25 μm, a width of 446 mm or a width of 1160 mm.

<Preparation of adhesive>

100 parts by weight of a polyvinyl alcohol resin (manufactured by Nippon Synthetic Chemical Co., Ltd.: Ecomat) and 35 parts by weight of a crosslinking agent (manufactured by Dainippon Ink Chemicals Co., Ltd.: WATERSOL) were dissolved in 3760 parts by weight of pure water to prepare The aqueous solution is then applied.

Example 1

(production of polarizing plate)

The above transparent protective film 1 having a width of 1330 mm (a ring-shaped olefin tree having a thickness of 25 μm) On one side of the lipid film, the above aqueous solution of the adhesive was applied so that the thickness of the adhesive layer after drying was 80 nm to obtain a transparent protective film 1 with an adhesive. On the other hand, the above-mentioned adhesive was applied to one side of the above-mentioned transparent protective film 2 (thickness of 40 μm of triacetyl cellulose film) having a width of 1,330 mm, and the thickness of the adhesive layer after drying was 80 nm. In the aqueous solution, a transparent protective film 2 with an adhesive is obtained. The coating of the above-mentioned adhesive-attached transparent protective films 1 and 2 is applied such that the width of the applied adhesive is the same as the width of the polarizing element having a width of 1160 mm, and is applied to each of the transparent protective films 1 and 2. The portions on both sides where the adhesive is not applied are substantially the same. Then, at a temperature of 23 ° C, on both sides of the polarizing element having a width of 1160 mm, the width w of the adhesive existing outward from the end portions of the polarizing element in the width direction of the polarizing element is 0. In the manner of mm, the transparent protective films 1 and 2 to which the above-mentioned adhesive agent is attached are simultaneously bonded by a roll machine. Then, a drying step of 10 minutes was carried out at 80 ° C to prepare a polarizing plate. In the obtained polarizing plate, the adhesive width w in the width direction of the polarizing plate was 0 mm, which is the aspect of FIG.

Examples 2 to 12 and Comparative Examples 1 to 12

In the first embodiment, the width of the polarizing element, the type of the first transparent protective film, the second transparent protective film, or the width w of the adhesive which is present from the end portion of the polarizing element toward the outside is changed as shown in Table 1. A polarizing plate was produced in the same manner as in Example 1 except that the widths of both sides were the same. Further, regarding the obtained polarizing plate, the case where the adhesive width w of the polarizing plate in the width direction is 0 mm is the aspect of Fig. 2, and the other cases are the same as those of Fig. 1. In the aspect of Fig. 1, the application of the adhesive for the above-mentioned transparent protective films 1 and 2 with an adhesive agent is controlled by the width w of the adhesive which is present from the end portion of the polarizing element toward the outside. The width of the agent.

In the above examples and comparative examples, the following evaluations were made when the polarizing plate was produced. The evaluation results are shown in Table 1.

(mobility)

Verification of the polarizing plate obtained in the production line of the polarizing plate on the basis of the following Motivation. ○: Moveable. ×: Cannot move.

A1, a2, a3‧‧‧ adhesive

P‧‧‧ Polarized components

T1‧‧‧1st transparent protective film

T2‧‧‧2nd transparent protective film

W _t1 ‧‧‧The width of the first transparent protective film T1

W _t2 ‧‧‧The width of the second transparent protective film T2

W _p ‧‧‧width of polarizing element

W1‧‧‧The width of the adhesive (a3)

W2‧‧‧The width of the adhesive (a3)

Claims (2)

A method for producing a polarizing plate, wherein a first transparent protective film is bonded to one surface of a polarizing element via an adhesive, and a second transparent protective film is bonded to the other surface via an adhesive to form a long polarizing plate. In the first transparent protective film and the second transparent protective film, when the dimensional change ratio (%) of the first transparent protective film is L1 and the dimensional change ratio of the second transparent protective film is L2 (%), the size The absolute value of the difference (L1-L2) of the change rate satisfies 0.10 or more, and the width of the polarizing element is equal to or less than the width of the first transparent protective film and the second transparent protective film, and is on both sides of the polarizing element in the width direction of the polarizing element. The width w (mm) of the adhesive present at the end toward the outside satisfies 0 w 75. The method of 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.