TW201434643A - Method of producing polarizable laminated film and polarizing plate, polarizable laminated film and polarizing plates set - Google Patents

Abstract

A method of producing a polarizable laminated film according to the present invention comprises a stretching step in which the laminated film comprising a 1<SP>st</SP> polyvinylalcohol resin layer, a base film and a 2<SP>nd</SP> polyvinylalcohol resin layer is stretched, and a dying step for dying, wherein in the dying step, when T1 is a period of time of the 1<SP>st</SP> polyvinylalcohol resin layer being brought into contact with the dying solution, and T2 is a period of time of the 2<SP>nd</SP> polyvinylalcohol resin layer being brought into contact with the dying solution, a absolute value of contact time difference percentage calculated by the following formula is more than 4%: Contact time difference percentage (%) = (T1-T2)/{(T1+T2)/2}*100.

Description

Polarizing laminated film and manufacturing method of polarizing plate, polarizing laminated film, and polarizing plate set

The present invention relates to a method for producing a polarizing laminated film and a polarizing plate, a polarizing laminated film, and a polarizing plate set.

A polarizing plate is widely used as a polarizing supply element of a display device such as a liquid crystal display device. As such a polarizing plate, a protective film made of triethyl fluorenyl cellulose adhered to a polarizing film (polarized sub-layer) made of a polyvinyl alcohol-based resin is used. In recent years, a notebook computer and a mobile phone with a liquid crystal display device have been used. The development of portable machines requires thin walls to be lightweight.

Conventionally, a film made of a polyvinyl alcohol-based resin is subjected to a dyeing treatment or a crosslinking treatment after being stretched alone, and a polarizing film is produced, and a polarizing film is laminated on a protective film or the like to produce a polarizing plate. The ultimate thickness when a separate polarizing film can be achieved. Therefore, it is known that after the polyvinyl alcohol-based resin layer is provided on the surface of the base film, the polyvinyl alcohol-based resin layer is stretched for each base film and dyed. In the cross-linking step and the subsequent drying step, the polyvinyl alcohol-based resin layer becomes a polarizing sub-layer, and the total thickness of the base film and the polarizing sub-layer can be made thin as a limit, as a polarizing sub-layer The thickness of the light film can be made thinner than the conventional one (for example, refer to Japanese Laid-Open Patent Publication No. 2000-338329 (Patent Document 1)).

Further, JP-A-2012-159778 (Patent Document 2) discloses a polyvinyl alcohol-based resin layer on a surface of both sides of a base film, and a polyvinyl alcohol-based resin layer is provided on each base film. The layer extends and is dyed. In the crosslinking step, a method in which a polyvinyl alcohol-based resin layer becomes a polarizing sub-layer and two polarizing sub-layers are obtained at the same time.

In the liquid crystal display device, two polarizing plates are used, one of which is disposed on the identification side of the liquid crystal cell, and the other is disposed on the backlight side of the liquid crystal cell. For example, in a small-sized liquid crystal display device, a polarizing plate on the backlight side, a brightness-increasing film, or the like, it is often used as a semi-transmissive reflection type. In this case, even if the polarizing function of the polarizing plate on the backlight side is not high, substantially Will reduce the contrast of the display device. Therefore, in the polarizing plate on the backlight side, even if the degree of polarization is slightly lower, the transmittance is brightened by design, and the transmittance as a liquid crystal display device is increased.

According to the method described in Patent Document 2, there is an advantage that two polarizing sublayers are simultaneously obtained. The present inventors have found that when a polarizing sub-layer having a high transmittance and a polarizing sub-layer having a low transmittance are simultaneously obtained, a polarizing plate set for constituting a liquid crystal display device having a high transmittance can be efficiently provided. In other words, the present invention provides a polarizing laminated film of two polarizing sublayers which simultaneously provide a difference in transmittance between the average values of transmittances of the sensibility-corrected monomers expressed in %, and more specifically in %. The manufacturing method and the manufacturing method of a polarizing plate are aimed. Further, it is an object of the invention to provide a polarizing laminated film having two polarizing sublayers having a high transmittance and the other having a low transmittance.

The present invention includes the following.

[1] A method for producing a polarizing laminated film, comprising: a base film; and a method for producing a polarizing laminated film formed on each of two polarizing layer layers on both surfaces of the base film, comprising the steps of: a step of forming a first polyvinyl alcohol-based resin layer on one surface of the film, forming a second polyvinyl alcohol-based resin layer on the other surface, forming a resin layer of the laminated film, and extending the step of extending the laminated film And the first polyvinyl alcohol-based resin layer and the second polyvinyl alcohol-based resin layer of the laminated film after the contact are brought into contact with a dye solution containing a dichroic dye, and dyed by the dichroic dye to form 2 a dyeing step of the polarizing layer; wherein, in the dyeing step, the time during which the first polyvinyl alcohol-based resin layer contacts the dyeing solution is T1, and the time when the second polyvinyl alcohol-based resin layer contacts the dyeing solution is T2 The ratio of the contact time difference calculated from the ratio (%) of the contact time difference = (T1 - T2) / {(T1 + T2) / 2} x 100 is more than 4% in absolute value.

[2] The method for producing a polarizing laminated film according to [1], wherein the ratio of the contact time difference is 4.5% or more in absolute value.

The method for producing a polarizing laminated film according to the above aspect, wherein the dyeing step is performed by the first polyvinyl alcohol-based resin layer and/or the second polyvinyl alcohol-based resin layer. The contact film is conveyed in the dyeing solution, and the first polyvinyl alcohol-based resin layer and the second polyvinyl alcohol-based resin layer are adjusted to contact the guide roller to adjust the first polyvinyl alcohol system. The time T1 at which the resin layer contacts the dyeing solution and the second polyvinyl alcohol-based resin layer contact the aforementioned The time T2 of the dyeing solution is such that the ratio of the aforementioned contact time difference becomes a desired numerical range.

The method for producing a polarizing laminated film according to any one of the above aspects of the present invention, characterized in that, after the dyeing step, the bonding protective film is provided on the surface of at least one of the polarizing sublayers step.

[5] The method for producing a polarizing laminated film according to [4], wherein the protective film is bonded to the surfaces of the two polarizing sublayers in the bonding step.

[6] A method for producing a polarizing plate, comprising the method of producing a polarizing plate comprising a polarizing layer and a protective film, comprising the step of preparing the polarizing laminated film obtained by the production method according to [4] or [5] And a layered body of the polarizing layer of the polarizing laminate film and the protective layer, which is peeled off from the base film to obtain a polarizing plate.

[7] The polarizing laminated film includes a base film and two polarizing sub-layers formed on both surfaces of the base film, wherein the two polarizing sub-layers have a transmittance-corrected monomer transmittance in % units The difference in average values exceeds 0.3 points.

[8] The polarizing laminated film according to [7], wherein a difference in an average value of the transmittance-corrected monomer transmittances expressed by % units of the two polarizing sub-layers is 0.45 or more.

[9] A polarizing plate set which is a polarizing plate set formed by two polarizing plates disposed on both sides of a liquid crystal cell used in a liquid crystal display device, wherein the two polarizing plates respectively include polarized light as described in [7] One of the aforementioned two polarizing sublayers of the laminated film.

According to the polarizing laminated film produced by the method of the present invention, the same can be used When two polarizing sublayers having different transmittances are obtained, two polarizing plates having different transmittances can be obtained at the same time.

1‧‧‧Base film

10‧‧‧Dyeing tank

Guide rollers on the lower side of 11A, 12A, 13A‧‧

11B, 12B‧‧‧ upper guide roller

20‧‧‧crosslinking slot

21‧‧‧1st polyvinyl alcohol resin layer

22‧‧‧2nd polyvinyl alcohol resin layer

201‧‧‧Single-layer film

202‧‧‧Two-layer film

30‧‧‧cleaning trough

31, 32‧‧‧ polarized sublayer

302‧‧‧Two-sided polarizing laminated film

41, 42‧‧‧ protective film

401‧‧‧Single-sided film

402‧‧‧Two-sided film

501a, 501b‧‧‧ polarizing plate

Fig. 1 is a schematic flow chart showing a method of manufacturing a polarizing plate of the present invention.

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

Fig. 3 is a schematic cross-sectional view showing an example of a method of treating a stretched film of the present invention.

Fig. 4 is a schematic cross-sectional view showing the dyeing tank of the first embodiment.

The present invention relates to a method for producing a polarizing laminated film and a polarizing plate, a polarizing laminated film, and a polarizing plate set. In the present specification, a laminate of a polyvinyl alcohol-based resin layer (a film composed of a polyvinyl alcohol-based resin) is provided on the surface of the base film, and is referred to as a "layered film". In the "layered film", the layered body having the polyvinyl alcohol-based resin layer on the surface on the side where the base film is used is a "single-area film", and the surface on both sides of the base film is provided with a polyvinyl alcohol-based resin. The layered layer of the layer is a "two-area layer film" to distinguish between the two.

Further, a polyvinyl alcohol-based resin layer having a function as a polarizer is referred to as a "polarized sub-layer", and a laminate of a base film and a polarizing layer is referred to as a "polarized laminated film". In the "polarized laminated film", the surface on the side where the base film is used is provided with a polarizing sub-layer as a "single-sided polarizing laminated film", and the surface on both sides of the base film is provided with a polarizing sub-layer as "two-sided polarizing" A laminated film to distinguish between the two. Further, at least one surface of the polarizing sub-layer is provided with a laminated body having a protective film, and is referred to as a "polarizing plate". Following, detailed Each constituent element of the polarizing laminated film, the polarizing plate, and the polarizing plate set will be described.

[Substrate film]

As the resin constituting the base film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, and elongation is preferably used, and an appropriate resin can be selected depending on the glass transition temperature (Tg) or melting point (Tm). . Specific examples of the thermoplastic resin include a polyolefin resin, a polyester resin, a cyclic polyolefin resin (northene-based resin), a (meth)acrylic resin, a cellulose ester resin, and a polycarbonate resin. Resin, polyvinyl alcohol resin, vinyl acetate resin, polyarylate resin, polystyrene resin, polyether oxime resin, polyfluorene resin, polyamine resin, polyimide resin, and Such mixtures, copolymers, and the like.

The base film may be a single layer of one type of the above-mentioned resin, or may be a mixture of two or more types of resins. Of course, it may not be a single layer and may be formed as a multilayer film.

The polyolefin resin is a polymer having a chain olefin as a main monomer such as ethylene or propylene. Further, a propylene-ethylene copolymer obtained by copolymerizing propylene with ethylene or the like can be used. The copolymerization may be other kinds of monomers, as other kinds of monomers which may be copolymerized with propylene, in addition to ethylene, such as an α-olefin. The α-olefin copolymerized with propylene is a carbon number of 4 or more, and more preferably an α-olefin having 4 to 10 carbon atoms. When a ?-olefin having 4 to 10 carbon atoms is cited, a linear monoolefin such as 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene or 3-decene; For example, 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1pentene branched monoolefins; vinylcyclohexane; The copolymer of propylene and other monomers which may be copolymerized therewith may be a random copolymer or a block copolymer. The content of the constituent unit derived from the other monomer in the copolymer can be 616 according to the "Handbook of Polymer Analysis" (issued by Kiyokiya Bookstore in 1995). The method described in the page is determined by measurement of an infrared (IR) spectrum. The polyolefin-based resin is preferably used as the substrate film of the present invention because it is easily and stably extended at a high rate.

Among the polyolefin-based resins, a propylene-based resin is preferable, and examples thereof include, for example, a propylene homopolymer, a propylene-ethylene random copolymer, a propylene-1-butene random copolymer, and a propylene-ethylene-1-butene. Arene random copolymer and the like.

The stereoregularity of the propylene resin is substantially isotactic or syndiotactic. A film composed of a propylene-based resin having substantially uniform or regular stereoregularity is preferable in use, and has high mechanical strength in a high-temperature environment.

The polyester resin is a polymer having an ester bond in a main chain, and is specifically composed of a polycondensate of a polyvalent carboxylic acid and a polyvalent alcohol. The polyvalent carboxylic acid to be used is mainly a divalent carboxylic acid or an ester thereof, such as terephthalic acid, isophthalic acid, dimethyl terephthalate or dimethyl naphthalate. Further, the polyvalent alcohol to be used is mainly a divalent alcohol such as propylene glycol, butylene glycol, neopentyl glycol, cyclohexane dimethanol or the like.

As a representative example of the polyester resin, for example, polyethylene terephthalate of a polycondensate of terephthalic acid and ethylene glycol. Polyethylene terephthalate is a crystalline resin, and in a state before the crystallization treatment (amorphous state), it is easy to carry out a treatment such as stretching. If necessary, the crystallization treatment can be carried out by heat treatment at the time of stretching or extension. Further, it is also suitable to use a copolymer of polyethylene terephthalate and copolymerize with other kinds of monomers to reduce the crystallinity (or to be amorphous) of the copolymerized polyester. As an example of such a resin, for example, cyclohexanedimethanol or isophthalic acid copolymerizer is used. These resins are suitable for use because of their excellent extendability.

Specific polyester resins other than polyethylene terephthalate and copolymers thereof, for example, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polypair Propylene phthalate, poly(propylene naphthalate), poly(cyclohexanedimethylene terephthalate), cyclohexanedimethyl dimethyl naphthalate, and the like. These blended resins and copolymers can also be used.

The cyclic polyolefin-based resin is a general term for a polymer having a cyclic olefin as a main constituent monomer, and is described in, for example, Japanese Laid-Open Patent Publication No. Hei. No. Hei. Resin. Specific examples include, for example, a ring-opened (co)polymer of a cyclic olefin, an addition polymer of a cyclic olefin, a copolymer of a cyclic olefin and an α-olefin such as ethylene or propylene (represented by a random copolymer) And such graft copolymers modified with unsaturated carboxylic acids and derivatives thereof, such hydrides and the like. Specific examples of the cyclic olefin include, for example, a norbornene-based monomer. As the cyclic polyolefin-based resin, a norbornene-based resin is particularly preferable.

Various products have been commercially available as cyclic polyolefin-based resins. Specific examples include TOPAS (manufactured by Topas Advanced Polymers), Arton (made by JSR Co., Ltd.), ZEONOR (made by Japan ZEON Co., Ltd.), ZEONEX (made by Japan ZEON Co., Ltd.), and APEL. (Mitsui Chemical Co., Ltd.) and so on.

The (meth)acrylic resin is a polymer having a (meth)acryl fluorenyl group as a main constituent monomer. For example, polymethyl methacrylate like polymethyl methacrylate, methyl methacrylate-(meth)acrylic acid copolymer, methyl methacrylate-(meth) acrylate copolymer, methacrylic acid a copolymer of an ester-acrylate-(meth)acrylic acid copolymer, a methyl (meth)acrylate-styrene copolymer (referred to as an MS resin, etc.), a methyl methacrylate and a compound having an alicyclic hydrocarbon group ( E.g Methyl methacrylate - cyclohexyl methacrylate copolymer, methyl methacrylate - methyl methacrylate copolymer, etc.). A polymer having a C1 to 6 alkyl ester of a (meth)acrylic resin such as polymethyl methacrylate as a main component is preferable. A more preferable example of the (meth)acrylic resin is, for example, a methyl methacrylate-based resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight).

The cellulose ester resin is an ester of cellulose and a fatty acid. Specific examples of such a cellulose ester-based resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Further, for example, the copolymer or a part of the hydroxyl group is modified by another substituent or the like. Among these, cellulose triacetate is particularly preferred. Many products of cellulose triacetate are commercially available, which is advantageous in terms of availability and cost. Examples of commercially available cellulose triacetate, such as Fujitac TD80 (made by Fuji Film Co., Ltd.), Fujitac TD80UF (made by Fuji Film Co., Ltd.), and Fujitac TD80UZ (made by Fuji Film Co., Ltd.) , Fujitac TD40UZ (manufactured by Fuji Film Co., Ltd.), KC8UX2M (manufactured by Konica Minolta Opto Co., Ltd.), KC4UY (manufactured by Konica Minolta Optical Co., Ltd.), and the like.

The polycarbonate resin-based main chain has a polymer of a carbonate bond (-O-CO-O-). It is a kind of engineering plastic which has high impact resistance, heat resistance and flame retardancy. Moreover, due to its high transparency, it is also suitable for optical applications. For optical use, in order to lower the photoelastic coefficient, a resin called a modified polycarbonate which is modified by a polymer skeleton, a copolymerized polycarbonate which improves wavelength dependence, and the like are also commercially available, and can be suitably used. Such a polycarbonate resin is widely commercially available, for example, PANLITE (manufactured by Teijin Chemicals Co., Ltd.), IUPILON (manufactured by Mitsubishi Engineering Plastics Co., Ltd.), SD POLYCA (manufactured by Sumitomo Corporation), CALIBRE (道) Chemical company system).

In addition to the above thermoplastic resin, any suitable additive may be added to the base film. As such an additive, for example, an ultraviolet absorber, an antioxidant, a slip agent, a plasticizer, a release agent, a coloring inhibitor, a flame retardant, a nucleating agent, an antistatic agent, a pigment, a colorant, and the like. In the base film, the ratio of the above-exemplified thermoplastic resin is desirably 50 to 100% by weight, more desirably 50 to 99% by weight, still more desirably 60 to 98% by weight, particularly desirably 70 to 97% by weight. %. When the ratio of the thermoplastic resin in the base film is less than 50% by weight, it may be difficult to sufficiently produce high transparency and the like which the thermoplastic resin originally has.

The thickness of the base film can be appropriately determined, and is generally preferably from 1 to 500 μm, more preferably from 1 to 300 μm, and particularly preferably from 5 to 200 μm from the viewpoint of workability, usability, and the like. Further, a substrate film having a thickness in the range of 5 to 150 μm is preferred.

In order to improve the adhesion to the resin layer, at least the surface on which the resin layer is formed may be subjected to corona treatment, plasma treatment, flame treatment, or the like. Further, in order to improve the adhesion, a thin layer such as a primer layer or an adhesive layer may be formed on the surface on which the resin layer side is formed. Further, when an adhesive layer, a corona treatment layer, or the like is provided, the base film refers to a state in which the state is not included.

[Undercoat]

On the surface of the substrate film, an undercoat layer can be formed. The undercoat layer may be formed of a material that exhibits a certain degree of adhesion to both the base film and the polyvinyl alcohol-based resin layer. For example, a thermoplastic resin excellent in transparency, heat stability, and elongation is used. Specifically, for example, an acrylic resin, a polyvinyl alcohol resin, or the like is not limited thereto.

The resin forming the undercoat layer can be made in a state of being dissolved in a solvent use. Depending on the solubility of the resin, aromatic hydrocarbons such as benzene, toluene, and xylene, ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, such as ethyl acetate and isobutyl acetate, may be used. A general organic solvent such as an ester such as a chlorinated hydrocarbon such as chlorinated ethylene, trichloroethylene or chloroform, or an alcohol such as ethanol, 1-propanol, 2-propanol or 1-butanol. However, when the undercoat layer is formed from a solution containing an organic solvent, it is preferable to select an appropriate solvent because the base film is dissolved and the solubility of the base film is also considered. When considering the influence on the environment, it is preferable to form an undercoat layer from a coating liquid using water as a solvent. Among them, a polyvinyl alcohol-based resin having good adhesion is preferred.

The polyvinyl alcohol-based resin used for the undercoat layer is specifically polyvinyl alcohol and a derivative thereof. As the polyvinyl alcohol derivative, in addition to polyvinyl formal or polyvinyl acetal, for example, an acrylic acid, an unsaturated carboxylic acid such as acrylic acid, methacrylic acid or crotonic acid, or an unsaturated carboxylic acid is used as the polyvinyl alcohol. Ester, acrylamide and other modified people. Among the above polyvinyl alcohol-based resins, polyvinyl alcohol is preferably used.

In order to increase the strength of the undercoat layer, a crosslinking agent may be added to the above thermoplastic resin. A crosslinking agent added to a thermoplastic resin can be used by a person skilled in the art of organic or inorganic. The thermoplastic resin to be used is appropriately selected as appropriate. For example, an epoxy crosslinking agent, an isocyanate crosslinking agent, a dialdehyde crosslinking agent, a metal crosslinking agent, or the like is appropriately selected.

As the epoxy-based crosslinking agent, either one-liquid curing type or two-liquid curing type can be used. For example, ethylene glycol diepoxypropyl ether, polyethylene glycol diepoxypropyl ether, glycerol di or triepoxypropyl ether, 1,6-hexanediol diepoxypropyl ether, trimethylol Propane triepoxypropyl ether, diepoxypropyl aniline, diepoxypropylamine, and the like.

As the isocyanate crosslinking agent, for example, tolyl diisocyanate, hydrogenated tolyl diisocyanate, trimethylolpropane-tolyl diisocyanate adduct, Triphenylmethane triisocyanate, methylene bis(4-phenylmethane) triisocyanate, isophorone diisocyanate, and such ketoxime blocks or phenolic blocks.

Examples of the dialdehyde crosslinking agent include glyoxal, malondialdehyde, succinaldehyde, glutaraldehyde, maleic aldehyde, and o-phthalaldehyde.

The metal-based crosslinking agent, for example, a metal salt, a metal oxide, a metal hydroxide, or an organometallic compound, may be appropriately selected from the viewpoint of the type of the metal.

As a metal salt, a metal oxide, and a metal hydroxide, for example, having a valence of two or more valences such as magnesium, calcium, aluminum, iron, nickel, zirconium, titanium, lanthanum, boron, zinc, copper, vanadium, chromium, and tin Metal salts, oxides thereof and hydroxides thereof.

The term "organometallic compound" refers to a compound having at least one metal atom in the molecule, and the metal atom is directly bonded to an organic group, or a structure in which an organic group is bonded via an oxygen atom or a nitrogen atom. Here, the organic group means a monovalent or polyvalent group containing at least a carbon element, for example, an alkyl group, an alkoxy group, a decyl group or the like. Further, the bonding means not only a covalent bond but also a coordination bond coordinated by a chelating compound or the like.

Examples of the metal organic compound suitable as a crosslinking agent include an organic titanium compound, an organic zirconium compound, an organoaluminum compound, and an organic onium compound. These metal organic compounds may be used alone or in combination of two or more.

Specific examples of the organotitanium compound include tetra-n-butyl titanate, tetraisopropyl titanate, butyl titanate dimer, tetrakis(2-ethylhexyl) titanate, and tetramethyl titanate. Titanium orthoesters; such as titanium acetonate, titanium tetraacetone, titanium acetonide, titanium octyl glycolate, titanium lactate, titanium triethanolamine, titanium acetate Ester titanium chelates; such as titanium bismuth compounds of titanium polyhydroxystearate.

Specific examples of the organic zirconium compound include zirconium n-propionate, zirconium n-butyrate, zirconium tetraethoxide, zirconium monoacetate, zirconium acetonate, zirconium acetoacetate, and ethyl zirconium acetate.

Specific examples of the organoaluminum compound include aluminum acetonate, aluminum organic acid chelates, and the like.

Specific examples of the organic ruthenium compound include compounds in which the ligands exemplified in the prior organotitanium compound and the organozirconium compound are bonded to ruthenium.

As the low molecular crosslinking agent described so far, a polymer crosslinking agent such as a methylolated melamine resin or a polyamine epoxy resin can also be used. As a commercial product of the polyamide resin, "SUMIREZ RESIN 650 (30)" and "SUMIREZ RESIN 675" (both are trade names) sold by the company are available from the company.

When a polyvinyl alcohol oxime resin is used as the undercoat layer-forming thermoplastic resin, a methylolated melamine, a dialdehyde, a metal ruthenium crosslinking agent or the like is preferably used as the crosslinking agent.

The ratio of the thermoplastic resin to the crosslinking agent used for forming the undercoat layer is in the range of 0.1 to 100 parts by weight based on 100 parts by weight of the resin, depending on the kind of the resin, the type of the crosslinking agent, and the like. It is preferable to decide, in particular, a range of 0.1 to 50 parts by weight. Further, the coating liquid for an undercoat layer preferably has a solid content concentration of from 1 to 25% by weight.

The thickness of the undercoat layer is preferably in the range of about 0.05 to 1 μm. More preferably, it is 0.1 to 0.4 μm. When the undercoat layer is too thin, the adhesion between the substrate film and the polyvinyl alcohol resin layer is low, and when the thickness is too thick, the polarizing plate itself becomes thick, so good.

The coating method to be used for the formation of the undercoat layer is not particularly limited, and is applied from a wire bar coating method such as reverse coating, gravure coating, a slit coating method, and a slanting wheel coating method. A conventional method such as a lip coating method, a spin coating method, a screen coating method, a fountain coating method, a dip coating method, or a spray coating method is appropriately selected.

[Polarizer]

The polarizing layer, specifically, the polyvinyl alcohol-based resin layer which is one-axis extending is dyed with a dichroic dye, and the dichroic dye is adsorbed to the alignment. A polyvinyl acetate-based resin can be used as a polyvinyl alcohol-based resin. As the polyvinyl acetate-based resin, in addition to polyvinyl acetate of a homopolymer of vinyl acetate, for example, a copolymer of vinyl acetate and a monomer copolymerizable therewith can be used. Examples of the monomer copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, acrylamides having an ammonium group, and the like.

Such a polyvinyl alcohol-based resin is formed into a film to constitute the polarizing sub-layer of the present invention. The method for forming a film of a polyvinyl alcohol-based resin is not particularly limited, and a film can be formed by a conventional method, and a polyvinyl alcohol-based resin solution is applied to the base from the point that a polarizing layer of a desired thickness can be easily obtained. Film formation on the film is ideal.

The polarizing sub-layer must be extended to be aligned, more preferably more than 5 times, more preferably more than 5 times and less than 17 times the stretching ratio.

The polarizer layer is a polyvinyl alcohol-based resin which is extended and aligned as described above to adsorb and align the dichroic dye. The thickness of the polarizer layer is 10 μm or less, and preferably 7 μm or less. By making the thickness of the polarizer layer 10 μm or less, a thin polarizing laminate film can be formed.

The polyvinyl alcohol resin used in the polarizing sublayer has a degree of saponification of 80 More than or equal to the molar percentage, and more than 90% by mole, especially more than 94% by mole. When the degree of saponification is too low, the water resistance and the moist heat resistance after the polarizing plate may become insufficient. Further, although it may be a completely saponified product (saponification degree: 100% by mole), when the degree of saponification is too high, the dyeing speed is slow, and in order to impart sufficient polarizing performance, the production time is prolonged, and depending on the case, it may not be sufficient. Polarized performance. Therefore, the degree of saponification is preferably 99.5 mol% or less, and preferably 99 mol% or less or 99.0 mol% or less.

Here, the degree of saponification refers to the ratio of the acetic acid group (acetoxy group: -OCOCH ₃ ) of the polyvinyl acetate-based resin contained in the raw material of the polyvinyl alcohol-based resin to the hydroxyl group by saponification treatment, in units of When the ratio (% by mole) is expressed, the following formula is defined. Degree of saponification (% by mole) = [(number of hydroxyl groups) ÷ (number of hydroxyl groups + number of acetate groups)] × 100

The higher the degree of saponification, the greater the ratio of hydroxyl groups, but means that the ratio of the acetate groups which hinder crystallization is small. The degree of saponification is determined by the method specified in JIS J6726-1994 "Testing methods for polyvinyl alcohol".

Further, the polyvinyl alcohol-based resin used in the present invention may be a partially modified modified polyvinyl alcohol. For example, a polyvinyl alcohol-based resin is modified by an olefin such as ethylene or propylene, a modified carboxylic acid such as acrylic acid, methacrylic acid or crotonic acid, or an alkyl ester modified with an unsaturated carboxylic acid. Modified by acrylamide, etc. The ratio of upgrading is less than 30% by mole, and it is more desirable to be less than 10%. When the modification is performed over 30 mol%, the dichroic dye becomes difficult to adsorb, and the polarizing performance is lowered, resulting in a problem.

The average degree of polymerization of the polyvinyl alcohol-based resin is usually in the range of from 100 to 10,000, more preferably from 1,500 to 8,000, still more preferably from 2,000 to 5,000. The average degree of polymerization herein is also determined by the method specified in JIS J6726-1994 "Testing methods for polyvinyl alcohol".

As the polyvinyl alcohol-based resin having such characteristics, for example, PVA124 (saponification degree: 98.0 to 99.0 mol%) manufactured by Kuraray Co., Ltd., PVA117 (saponification degree: 98.0 to 99.0 mol%), PVA624 ( Saponification degree: 95.0 to 96.0 mol%) and PVA617 (saponification degree: 94.5 to 95.5 mol%); for example, AH-26 (saponification degree: 97.0 to 98.8 mol%) manufactured by Nippon Synthetic Chemical Co., Ltd., AH-22 (saponification degree: 97.5 to 98.5 mol%), NH-18 (saponification degree: 98.0 to 99.0 mol%), and N-300 (saponification degree: 98.0 to 99.0 mol%); for example, JC manufactured by VAM & POVAL Co., Ltd., Japan -33 (saponification degree: 99.0 mol% or more), JM-33 (saponification degree: 93.5 to 95.5 mol%), JM-26 (saponification degree: 95.5 to 97.5 mol%), JP-45 (saponification degree: 86.5 to 89.5 mol%), JF-17 (saponification degree: 98.0 to 99.0 mol%), JF-17L (saponification degree: 98.0 to 99.0 mol%), and JF-20 (saponification degree: 98.0 to 99.0 mol%) %), etc., in the present invention, these can be suitably used.

The dichroic dye used for dyeing the polyvinyl alcohol-based resin layer specifically includes iodine or a dichroic organic dye. As a dichroic organic dye, such as red BR, red LR, red R, pink LB, rubin BL, Bordeaux GS, sky blue LG, lemon yellow, blue BR, blue 2R, navy RY, green LG, purple LB , Purple B, Black H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlett GL, Scarlett KGL, Congo Red, Bright Purple BK, Super (SUPRA) Blue G, Super Blue GL, Super Orange GL, Direct Sky Blue, Direct Fast Orange S, Fast Black, etc. These dyes are available on the market. The dichroic dye may be used alone or in combination of two or more.

[protective film]

The protective film may be a simple protective film having no optical function, or may be a protective film having an optical function such as a retardation film or a brightness enhancement film. The material that constitutes the protective film, There is no particular limitation, and for example, a cyclic polyolefin-based resin, a cellulose acetate-based resin such as triethyl fluorenyl cellulose or diethyl acetoxy cellulose, a polyester resin such as polyethylene terephthalate, or the like may be used. A material widely used in the art such as a polycarbonate resin, an acrylic resin, or a polypropylene resin.

As a cyclic polyolefin resin, a suitable commercial product can be suitably used, for example, TOPAS (manufactured by Topas), Arton (made by JSR Co., Ltd.), ZEONOR (made by Japan ZEON Co., Ltd.), and ZEONEX (Japan ZEON) Co., Ltd.), APEL (manufactured by Mitsui Chemicals, Inc.), etc. When such a film made of a cyclic polyolefin resin is used as a film, a conventional method such as a solvent casting method or a melt extrusion method is suitably used. In addition, in the case of a film prepared in advance, such as ESCENA (made by Sekisui Chemical Co., Ltd.) and ZEONOR film (made by Japan ZEON Co., Ltd.), a ring-shaped polyolefin resin film with a phase difference may be used depending on the case. Sale.

The cyclic polyolefin resin film may be one-axis extension or biaxial extension. By extending, it is possible to impart an arbitrary retardation value to the cyclic polyolefin resin film. The stretching is usually carried out continuously while winding up the film roll, and in the heating furnace, it extends in the traveling direction of the roll, the direction perpendicular to the traveling direction thereof, or both directions. The temperature of the heating furnace is usually in the range from the vicinity of the glass transition temperature of the cyclic polyolefin resin film to the glass transition temperature + 100 °C. The magnification of the extension is usually 1.1 to 6 times, preferably 1.1 to 3.5 times, in one direction.

The cyclic polyolefin resin film generally has poor surface activity, and is subjected to surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame treatment, and saponification treatment on the surface adhering to the polarizing layer. More ideal. Among them, plasma treatment and corona treatment which are relatively easy to implement are suitable.

As a cellulose acetate-based resin film, a suitable commercial product is suitably used. For example, Fujitac TD80 (made by Fuji Film Co., Ltd.), Fujitac TD80UF (made by Fuji Film Co., Ltd.), Fujitac TD80UZ (made by Fuji Film Co., Ltd.), Fujitac TD40UZ (made by Fuji Film Co., Ltd.), KC8UX2M (Konica) Minolta Optical Co., Ltd.), KC4UY (manufactured by Konica Minolta Optical Co., Ltd.), etc.

On the surface of the cellulose acetate-based resin film, a liquid crystal layer or the like can be formed in order to improve the viewing angle characteristics. Further, in order to impart a phase difference, an extended cellulose acetate resin film can be used. The cellulose acetate-based resin film is usually subjected to a saponification treatment in order to improve the adhesion to the polarizing layer. The saponification treatment can be carried out by immersing the film in an aqueous alkali solution such as sodium hydroxide or potassium hydroxide.

On the surface of the above protective film, an optical layer such as a hard coat layer, an antiglare layer, and an antireflection layer can be formed. The method of forming the optical layers on the surface of the protective film is not particularly limited, and a conventional method can be used.

The thickness of the protective film is preferably as small as possible from the viewpoint of thinning, and is preferably 90 μm or less, and more preferably 50 μm or less. On the other hand, when it is too thin, since the workability is hindered due to the decrease in strength, it is preferably 5 μm or more.

<Method of Manufacturing Polarizing Plate>

Fig. 1 is a schematic flow chart showing a method of manufacturing a polarizing plate of the present invention. Fig. 2 is a schematic cross-sectional view showing an example of a method of producing a polarizing plate of the present invention. In the method for producing a polarizing laminated film of the present invention, the method further comprises: forming a polyvinyl alcohol-based resin layer on both surfaces of the base film to obtain a resin layer forming step of the two-area film (S10); and extending the two-layer film The step of extending (S20); the step of bringing the polyvinyl alcohol-based resin layer on both sides of the stretched two-layer film into contact with the dye solution containing the dichroic dye and dyeing with the dichroic dye (S30). After the dyeing step (S30), The cross-linking step (S35) of performing the cross-linking treatment is usually carried out to form a polarizing sub-layer.

Furthermore, in order to make a polarizing plate, etc., the two-layer film is washed in sequence. Drying and drying step (S40); bonding the protective film on both sides or one side of the two-layer film to obtain a protective film bonding step of the double-sided bonding film or the single-sided bonding film (S50); drying the two-side bonding a drying step (S60) of the film or the single-sided bonding film; and a peeling step (S70) of peeling off the polarizing plate from the double-sided bonding film or the single-sided bonding film.

In the method for producing a polarizing laminate film of the present invention, a polyvinyl alcohol-based resin layer is formed on both surfaces of the substrate film. By such a manufacturing method, two polarizing plates can be simultaneously manufactured.

<Production steps>

Hereinafter, each step of S10 to S70 will be described in detail based on the first and second figures.

[Resin layer forming step (S10)]

Here, a polyvinyl alcohol-based resin layer (the first polyvinyl alcohol-based resin layer 21 and the second polyvinyl alcohol-based resin layer 22) is formed on both surfaces of the base film 1, and a base film and a polyvinyl alcohol-based resin are obtained. A two-layer film 202 composed of layers 21 and 22.

The material suitable for the base film 1 is as described in the description of the configuration of the above polarizing laminated film. Further, the base film 1 is preferably used in a temperature range in which a suitable polyvinyl alcohol-based resin is stretched. It is preferable that the materials of the two polyvinyl alcohol-based resin layers 21 and 22 formed on both surfaces of the base film 1 are the same material. The polarizing performance of the polarizing sub-layer formed thereby can be easily adjusted by using the same material.

Further, it is preferable that the polyvinyl alcohol-based resin layers 21 and 22 on both sides of the extended two-layer film have the same thickness. The specific thickness of the polyvinyl alcohol-based resin layers 21 and 22 formed in the resin layer forming step (S10) is more preferably 3 μm or more and 30 μm or less, and more preferably 5 to 20 μm. The initial resin layer has a thickness of 3 When it is not more than μm, it becomes too thin after stretching, and the dyeability is remarkably deteriorated, which is not preferable. On the other hand, when the thickness exceeds 30 μm, the thickness of the finally obtained polarizing sub-layer exceeds 10 μm, which is not preferable.

The polyvinyl alcohol-based resin layers 21 and 22 are preferably dissolved in a good solvent, and the obtained polyvinyl alcohol-based resin solution is applied onto the surface of one side of the base film to evaporate the solvent. Formed by drying. The polyvinyl alcohol-based resin layers 21 and 22 are formed by this, and the polyvinyl alcohol-based resin can be made thin. As a method of applying a polyvinyl alcohol-based resin solution to a base film, a roll coating method such as a bar coating method, a reverse coating method, or a gravure coating method, a slit coating method, or a slanting wheel coating method A conventional method such as a lip coating method, a spin coating method, a screen coating method, a fountain coating method, a dip coating method, or a spray coating method can be appropriately selected and used. The drying temperature is, for example, 50 to 200 ° C, preferably 60 to 150 ° C. The drying time is, for example, 2 to 20 minutes.

The application of the polyvinyl alcohol-based resin layer on both surfaces of the base film 1 can be carried out one by one by the above method, or by dip coating, spray coating, or other special means, on both sides of the base film. At the same time, a polyvinyl alcohol-based resin layer was applied.

Further, in order to improve the adhesion between the base film 1 and the polyvinyl alcohol-based resin layers 21 and 22, an undercoat layer may be provided between the base film 1 and the polyvinyl alcohol-based resin layers 21 and 22. The undercoat layer can be formed of a composition containing a polyvinyl alcohol-based resin and a crosslinking agent, and is preferable from the viewpoint of adhesion. The material suitable for the undercoat layer or the like is as described in the description of the configuration of the above polarizing plate.

When the undercoat layer is provided, the order of application of the base film 1 is not particularly limited. After the undercoat layer is formed on both surfaces of the base film, the polyvinyl alcohol-based resin layers 21 and 22 are formed on both sides thereof. The undercoat layer and the polyvinyl alcohol-based resin layer 21 may be sequentially formed on one surface of the base film 1, and the single-layer film 201 may be formed on the substrate film. On the other side surface, an undercoat layer and a polyvinyl alcohol-based resin layer 22 are sequentially formed.

[Extension step (S20)]

Here, the two-area layer film 202 obtained in the resin layer forming step (S10) is extended. It is preferable to extend the shaft by one of the stretching ratios of more than 5 times and 17 times or less. Further, it is more desirable to extend the axis by one of the stretching ratios of more than 5 times and 8 times or less. When the stretching ratio is 5 times or less, the polyvinyl alcohol-based resin layer cannot be sufficiently aligned, and as a result, the degree of polarization of the polarizing sub-layer cannot be sufficiently increased, which causes a problem. On the other hand, when the stretching ratio exceeds 17 times, the elongation of the laminated film is likely to occur at the time of stretching, and the thickness of the laminated film after stretching becomes thinner than the required thickness, and the workability in the subsequent step. Operationality may be reduced. The extension process of the extension step (S20) is not limited to the extension of one stage, and can be performed in multiple stages. In this case, the stretching step after the second stage may be carried out in the stretching step (S20), or the dyeing step (S30) and the crosslinking step (S35) may be simultaneously performed. In the case where the multi-stage stretching is performed in this way, the stretching process is performed in a total of more than 5 times the stretching magnification in all the stages of the stretching process.

In the extending step (S20) of the present embodiment, a longitudinal stretching process in the longitudinal direction of the laminated film, a lateral stretching process in which the width direction is extended, and the like can be performed. As the longitudinal stretching treatment, for example, a method of stretching between rolls, a method of compressive stretching, or the like, as a lateral stretching treatment, for example, a tenter method or the like.

Moreover, the extension treatment of the present invention is preferably carried out using a dry stretching method. The polyvinyl alcohol-based resin layer of each base film is stretched by dry stretching before the dyeing step, and is not broken by a conventional thin polyvinyl alcohol-based resin layer, and can be stretched at a high magnification, and the obtained polarizing plate may be thinned.

[Staining step (S30)]

Here, a dichroic dye is used to make the polyethylene on both sides of the two-layer film 202 The alcohol resin layers 21 and 22 were dyed. The dichroic pigment is as described previously.

The dyeing step is carried out, for example, by immersing the entire stretched film by the solution (dyeing solution) containing the dichroic dye described above. As the dyeing solution, a solution in which the above dichroic dye is dissolved in a solvent can be used, and as a solvent of the dyeing solution, water is generally used, and an organic solvent compatible with water may be further added. The concentration of the dichroic dye is desirably 0.01 to 10% by weight, more desirably 0.02 to 7% by weight, and particularly desirably 0.025 to 5% by weight.

When iodine is used as the dichroic dye, it is preferable to add iodide because the dyeing efficiency can be further improved. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, cesium iodide, calcium iodide, tin iodide, and titanium iodide. The addition ratio of the iodides is preferably 0.01 to 20% by weight in the dyeing solution. Among the iodides, it is preferred to add potassium iodide. When adding potassium iodide, the ratio of iodine to potassium iodide is preferably in the range of 1:5 to 1:100 by weight, more preferably in the range of 1:6 to 1:80, and particularly preferably in the range of 1:7 to 1:70. .

The immersion time of the stretching film to the dyeing solution is not particularly limited, and is usually in the range of 15 seconds to 15 minutes, and more preferably 1 minute to 3 minutes. Further, the polyvinyl alcohol-based resin layer (the first polyvinyl alcohol-based resin layer) on one side of the stretched film is in contact with the dyeing solution for T1, and the other side is a polyvinyl alcohol-based resin layer (second polyvinyl alcohol-based) When the time when the resin layer is in contact with the dyeing solution is T2, the contact calculated from the following formula (1): ratio of contact time difference (%) = (T1 - T2) / {(T1 + T2) / 2} x 100 (1) The ratio of the time difference is more than 4% in absolute value, more preferably 4.5% or more.

According to the present invention, by making the absolute value of the ratio of the contact time difference more than 4%, two polarizing sublayers having different transmittances can be simultaneously obtained, for example, in % units. The difference in the average value of the transmittance of the apparent sensitivity correction monomer exceeds two polarizing sublayers of 0.3 points. Various methods can be selected as a method of adjusting the times T1 and T2 of the polyvinyl alcohol-based resin layer in contact with the dyeing solution. When the two-area layer film 202 is in contact with the guide roll, it can be considered that the polyvinyl alcohol-based resin layer 21 or 22 facing the guide roll does not contact the dyeing solution, as a method of adjusting T1 and T2, for example, by designing the size (diameter) of the guide roll. The method of adjustment; the method of adjusting the contact length of the path design with the guide roller; the method of changing the contact length with the guide roller by the lift roller which can change the position; the method of adjusting the adjustment, and the like. Among them, the method of the path means is relatively simple, so it is ideal. However, since it is fixed and difficult to fine-tune, it can be used in combination with an adjustable lifting roller. Further, for example, when the film is conveyed in the air, the solution may be contacted with a shower or the like to finely adjust the contact time of the polyvinyl alcohol-based resin layer with the dyeing solution. The shower can be made by piping in the pipe, but when the shower is applied directly to the film, it is preferable to spray from a nozzle or the like in order to make the film more uniformly contact with the solution.

A specific example of the adjustment method will be described later in the first embodiment.

Further, the temperature of the dyeing solution is preferably in the range of 10 to 60 ° C, more preferably in the range of 20 to 40 ° C.

Further, the dyeing treatment may be carried out before or during the stretching step, but in order to allow the dichroic dye adsorbed to the polyvinyl alcohol-based resin to be well aligned, it is preferable to carry out the dyeing treatment after the stretching step of the unstretched film. . At this time, the film which is previously extended to the target magnification can be simply dyed, and the film which is extended to the low magnification in advance can be stretched again in the dyeing to achieve the magnification of all the objects. Further, when the stretching is further performed in the subsequent crosslinking treatment, the total stretching ratio at the end of the dyeing treatment can be set in advance to be lower than the final magnification of the object. In this case, after the crosslinking treatment, it may be appropriately processed to achieve the desired magnification.

[Crosslinking step (S35)]

After the dyeing step (S30), a crosslinking step (S35) for performing a crosslinking treatment is usually provided. The crosslinking treatment is carried out, for example, by dipping a laminated film in a solution (crosslinking solution) containing a crosslinking agent. As the crosslinking agent, a conventionally known one can be used. For example, a boron compound such as boric acid or borax, glyoxal, glutaraldehyde or the like. These may be one type or two or more types may be used in combination.

As the crosslinking solution, a solution in which a crosslinking agent is dissolved in a solvent can be used. As the solvent, for example, water may be used, or an organic solvent compatible with water may be contained. The concentration of the crosslinking agent in the crosslinking solution is not particularly limited, but is preferably in the range of 1 to 20% by weight, more preferably 6 to 15% by weight.

In the crosslinking solution, an iodide may be added. By adding an iodide, the in-plane polarization characteristics of the resin layer can be made more uniform. As the iodide, for example, potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, cesium iodide, calcium iodide, tin iodide, or titanium iodide. The content of the iodide is 0.05 to 15% by weight, more desirably 0.5 to 8% by weight.

The immersion time of the stretched film in the crosslinking solution is not particularly limited, and is usually in the range of 15 seconds to 20 minutes, and more preferably 30 seconds to 15 minutes.

Further, the crosslinking treatment can be carried out simultaneously with the dyeing treatment by blending the crosslinking agent in the dyeing solution. Further, the person who has previously extended to the target magnification can be simply cross-linked, and the cross-linking treatment and extension can be performed at the same time. The stretched film which was previously extended to the low magnification in the stretching step was stretched again in the crosslinking treatment to achieve the magnification of all the purposes.

By the above dyeing step (S30) and the crosslinking step (S35), the polyvinyl alcohol-based resin layers 21 and 22 have functions as the polarizing sub-layers 31 and 32, and A double-sided polarizing laminate film 302 can be obtained.

[Washing step (S40)]

Then, it is preferable to carry out a washing step of washing the double-sided polarizing laminated film 302. As a washing step, a water washing treatment can be performed. The water washing treatment is usually carried out by using pure water such as ion-exchanged water or distilled water as a washing liquid, by immersing the stretched film therein. The water washing temperature is usually from 3 to 50 ° C, preferably from 4 ° C to 20 ° C.

The washing step may be combined with a washing treatment of an iodide solution and a water washing treatment, and a solution of a liquid alcohol such as methanol, ethanol, isopropanol, butanol or propanol may be appropriately used as a washing liquid. . Further, after the washing step, a draining step using a nip roll, an air knife, or the like may be provided.

The immersion time of the cleaning film in the washing step to the cleaning liquid is usually 2 to 300 seconds, preferably 3 seconds to 240 seconds.

After the washing step, it is preferred to dry the two-sided polarizing laminate film. As the drying step, any suitable method (for example, natural drying, air drying, and heat drying) can be employed. For example, the drying temperature at the time of heat drying is usually 20 to 95 ° C, and the drying time is usually about 1 to 15 minutes.

[Protective film bonding step (S50)]

Here, the protective film is bonded to the surface or both surfaces of the double-sided polarizing laminate film 302 subjected to the above-described steps, that is, on the surface of the polarizing sublayer on one side or the surface of the polarizing sublayer on both sides. In the second drawing, a method of bonding the protective films 41 and 42 to the surfaces of the polarizing sub-layers 31 and 32 on both sides is schematically shown. As a method of bonding the polarizing sub-layer and the protective film, for example, a method of bonding the polarizing layer and the protective film via an adhesive layer or an adhesive layer. A material suitable as a protective film, such as a description of the constitution of the above polarizing plate Said.

(adhesive layer)

The adhesive constituting the pressure-sensitive adhesive layer is usually an acrylic resin, a styrene resin, a silicone resin or the like as a matrix polymer, and an isocyanate compound, an epoxy compound, an aziridine compound or the like is added thereto. The composition of the crosslinking agent is composed. Further, in the adhesive, fine particles are blended to form an adhesive layer which exhibits light scattering properties.

The thickness of the adhesive layer is preferably from 1 to 40 μm, and the thin coating is preferably in the range of characteristics of non-destructive workability and durability, and more preferably from 3 to 25 μm. When it is 3 to 25 μm, it has good workability and can suppress dimensional change of the polarizing film, which is a suitable thickness. When the adhesive layer is less than 1 μm, the adhesiveness is lowered, and when it exceeds 40 μm, problems such as bleeding of the adhesive tend to occur.

The method of forming the pressure-sensitive adhesive layer on the protective film or the polarizer is not particularly limited, and a solution containing each component represented by the matrix polymer may be applied to the surface of the protective film or the surface of the polarizing layer. After drying to form an adhesive layer, it is bonded to a release film or another type of film, or an adhesive layer may be formed on the release film, and then adhered to the surface of the protective film or the surface of the polarizing layer to be laminated. Further, when the adhesive layer is formed on the surface of the protective film or the surface of the polarizing sub-layer, the surface of the protective film or the surface of the polarizing layer or one side or both sides of the adhesive layer may be subjected to an adhesion treatment as needed. For example, corona treatment and the like.

(adhesive layer)

As the adhesive agent constituting the adhesive layer, for example, a water-based adhesive such as a polyvinyl alcohol-based resin aqueous solution or an aqueous two-liquid polyurethane emulsion adhesive is used. Among them, a polyvinyl alcohol-based resin aqueous solution is suitably used. For the use of polyvinyl alcohol as an adhesive a resin, in addition to a vinyl alcohol homopolymer obtained by saponification of polyvinyl acetate of a homopolymer of vinyl acetate, for example, a vinyl alcohol obtained by saponification of a copolymer of vinyl acetate and a monomer copolymerizable therewith A copolymer, a modified polyvinyl alcohol polymer modified with such a hydroxyl group, or the like. As the water-based adhesive, a polyvalent aldehyde, a water-soluble epoxy compound, a melamine-based compound, a zirconia compound, a zinc compound or the like can be added as an additive. When such a water-based adhesive is used, the adhesive layer obtained therefrom is usually much thinner than 1 μm, and its cross section is observed under a usual optical microscope, and the adhesive layer is not actually observed.

The bonding method of the film using the water-based adhesive is not particularly limited, and for example, a method of uniformly coating or pouring an adhesive on the surface of the film, laminating the coated surface with another film, laminating by a roll or the like, drying, or the like. Usually, the adhesive is applied at a temperature of 15 to 40 ° C after the preparation, and the bonding temperature is usually in the range of 15 to 30 ° C.

In the case of a water-based adhesive, after the film is bonded, the water contained in the aqueous binder is removed and dried. The temperature of the drying oven is preferably from 30 to 90 °C. When it is less than 30 °C. There is a tendency for the surface to be easily peeled off. When it exceeds 90 ° C or more, the optical performance of a polarizer or the like may be deteriorated due to heat. The drying time can be from 10 to 1000 seconds.

After drying, it is cured at room temperature or a temperature slightly higher than it, for example, at a temperature of about 20 to 45 ° C for an extent of 12 to 600 hours. The temperature at the time of curing is generally set to a temperature lower than the temperature used at the time of drying.

Further, as the nonaqueous binder, a photocurable adhesive can be used. As the photocurable adhesive, for example, a mixture of a photocurable epoxy resin and a photocationic polymerization initiator, and the like.

A method of bonding a film with a photocurable adhesive can be carried out by a conventional method such as a flow casting method, a Meyer bar coating method, a gravure coating method, or the like. A method of applying a contact agent to the adhesion surface of the film and laminating two films by a notch wheel coating method, a doctor blade coating method, a slit coating method, a dip coating method, a spray method, or the like. The term "flow casting method" refers to a method in which two films of a coated object are moved in an oblique direction in a direction perpendicular to the vertical direction, in a horizontal direction, or both, and an adhesive is applied to the surface thereof to open the film.

After applying an adhesive to the surface of the film, the bonded film is sandwiched by a nip roll or the like and adhered thereto. Further, a method of uniformly expanding the laminated body by a press or the like may be used. In this case, as the material of the roller, metal, rubber, or the like can be used. Further, it is preferable to use the laminated body to pass between the roller and the roller and to expand by pressurization. In this case, the rolls may be of the same material or of different materials. The thickness of the adhesive layer after bonding using the above-described nip rolls or the like is preferably 0.01 μm or more and 5 μm or less.

In order to improve adhesion, the surface of the film may be subjected to surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame treatment, or saponification treatment. The saponification treatment can be carried out by immersing the film in an aqueous alkali solution such as sodium hydroxide or potassium hydroxide.

When a photocurable resin is used as the adhesive, the photocurable adhesive can be cured by irradiating the active energy ray after the film is laminated. The light source of the active energy ray is not particularly limited, but an active energy ray having a luminescent distribution having a wavelength of 400 nm or less is preferable, and specifically, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultra high pressure mercury lamp, a chemical lamp, a black light lamp are used. Microwave-excited mercury lamps and metal halide lamps are ideal.

The light irradiation intensity of the photocurable adhesive is appropriately determined depending on the composition of the photocurable adhesive, and is not particularly limited. However, the irradiation intensity in a wavelength region effective for activation of the polymerization initiator is 0.1 to 6000 mW/cm ^{2 .} Ideal. By appropriately selecting the irradiation intensity in this range, the reaction time does not become too long, and the yellowing of the adhesive and the deterioration of the polarizing plate due to the heat radiated from the light source and the heat generation at the time of curing of the photocurable adhesive can be suppressed. The possibility. The light irradiation time of the photocurable adhesive is not particularly limited as long as it is applicable to the cured photocurable adhesive, but the cumulative light amount indicating the product of the irradiation intensity and the irradiation time is set to 10 to 10000 mJ/cm. ² is ideal. By appropriately selecting the amount of accumulated light of the photocurable adhesive to be in this range, the active species derived from the polymerization initiator can be produced in a sufficient amount, and the curing reaction can be performed more surely, and the irradiation time does not become too long. Maintain good productivity. The thickness of the adhesive layer after hardening is usually 0.001 to 5 μm, more preferably 0.01 μm or more, and still more preferably 2 μm or less.

When the photocurable adhesive between the polarizer layer and the protective film is cured by irradiation with an active energy ray, the polarizing plate, the transmittance, the hue, and the transparency of the protective film of the polarizing layer are polarized. It is preferable to perform hardening under various conditions without lowering the function.

[Drying step (S60)]

In the protective film bonding step (S50), in order to form a solution containing a solvent in order to form an adhesive layer or an adhesive layer, drying of the double-sided bonding film or the single-sided bonding film is performed. In the drying step, mainly for drying the adhesive layer or the adhesive layer, drying conditions and the like are the same as the drying treatment described in the above washing step (S40). In particular, in order to form an adhesive layer, when a polyvinyl alcohol-based resin aqueous solution or the like is used, it is preferred to carry out drying at a temperature of 60 ° C or higher.

[Peeling step (S70)]

After the drying step (S60), the laminated film or the single-sided bonding film is applied to laminate the polarizing layer 31 and the protective film 41 or the polarizing layer 32 and the protective film 42. The body is peeled off from the base film 1, and a peeling step (S70) of the polarizing plates 501a and 501b is obtained. The peeling method of the laminate is not particularly limited, and the same method as the peeling step of the release film by a usual polarizing plate with an adhesive can be employed. After the drying step (S60), it may be peeled off as it is, or may be wound up in a roll shape, and a peeling step may be provided to perform peeling. The polarizing plates 501a and 501b can be provided as a polarizing plate set, for example, disposed on both sides of a liquid crystal cell of a liquid crystal display device, and can be provided for use as a polarizing plate set. The polarizing plates 501a and 501b to which the protective films 41 and 42 are bonded to one side may be used as they are, or may be provided on the surface of the polarizing sub-layer 31 on the opposite side to the surface of the protective film 41 on which the polarizing plate 501a is provided, or The surface of the polarizing layer 32 on the opposite side of the surface of the protective film 42 of the polarizing plate 501b is laminated with a protective film or another optical layer to be described later.

[other optical layers]

The polarizing plate obtained by the present invention can be used as a polarizing plate for laminating other optical layers in actual use.

As an example of another optical layer, for example, a reflective polarizing film that reflects light having a polarized light of opposite nature by a certain polarized light, a film with an anti-glare function having a concave-convex shape on the surface, and a surface anti-reflection function A film, a reflective film having a reflective function on the surface, a semi-transmissive reflective film having both a reflective function and a transmissive function, and a viewing angle compensation film.

A commercially available product of a reflective polarizing film that reflects light that exhibits polarized light of opposite nature by a certain amount of polarized light, for example, DBEF (made by 3M Company, available from Sumitomo 3M Co., Ltd. in Japan), APF (3M) Company system, available in Japan from Sumitomo 3M Co., Ltd.), etc. As the viewing angle compensation film, for example, the surface of the substrate is coated with a liquid crystal compound to align it. A phase composed of a fixed optical compensation film, a retardation film made of a polycarbonate resin, and a cyclic polyolefin resin Bad film, etc. The liquid crystal compound is coated on the surface of the substrate to align it. A commercially available product of a fixed optical compensation film, such as WV film (made by Fuji Film Co., Ltd.), NH film (made by JX Nippon Mining & Energy Co., Ltd.), and NR film (made by JX Nippon Mining & Energy Co., Ltd.) )Wait. In addition, as a commercial product of a retardation film composed of a cyclic polyolefin resin, for example, ARTON film (manufactured by JSR Co., Ltd.), ESCENA (made by Sekisui Chemical Co., Ltd.), and ZEONOR film (Japan ZEON shares) Ltd.) and so on.

[Visual sensitivity correction monomer transmittance]

The average value of the transmittance-corrected monomer transmittance of the polarizing sub-layers 31 and 32 of the double-sided polarizing laminated film 302 is expressed as a difference in % (the average of the single transmittance is corrected from the visibility of the polarizing layer 31). The value obtained by subtracting the value of the average value of the transmittance correction monomer transmittance of the polarizing sub-layer 32 is more than 0.3%, more preferably 0.45% or more. The polarizing plates 501a and 501b each having the polarizing sub-layers 31 and 32 are preferably used as polarizing plate sets having different transmittances by correcting the difference between the average values of the transmittances of the illuminance included in such a range. A polarizing plate set for a liquid crystal display device is desired.

Here, the monomer transmittance which is the basis of the transmittance-corrected monomer transmittance is a numerical value defined by the following formula.

Monomer transmittance (λ) = 0.5 (Tp(λ) + Tc(λ))

Here, Tp(λ) is the transmittance (%) of the polarizing sub-layer measured by the linear polarized light of the incident wavelength λ nm and Parallel Nicol, and Tc (λ) is the straight line of the incident wavelength λ nm. The transmittance (%) of the polarizer layer measured under the relationship between the polarized light and Cross Nicol was measured together with the polarized ultraviolet visible light absorption spectrum of the spectrophotometer. Moreover, the monomers obtained at each wavelength The transmittance (λ), plus the sensitivity correction of the so-called visual sensitivity correction, is called the visual sensitivity correction single transmittance (Ty). Ty can be measured, for example, simply by a spectrophotometer (model: V7100) manufactured by JASCO Corporation. The V7100 measures the monomer transmittance in the visible light range (380 nm to 780 nm) on a scale of 5 nm, for example, and automatically performs subsequent processing to output Ty. Further, the average value of the transmittance-corrected single transmittance is measured for each of the polarizing sub-layers 31 and 32 by measuring the transmittance of the opacity-corrected monomer in a plurality of places, and averaging them. In the measurement, the in-plane directions of the polarizing layers 31 and 32, respectively, in the width direction of the film, that is, in the direction of the vertical extension are preferably 10 or more. In the examples described later, the effective width portion of the film in the width direction was divided into 11 portions, and the transmittance was corrected for the 11-point measurement, and the average value was obtained.

The measurement of the transmittance of the illuminance-corrected monomer varies depending on the presence or absence of the protective film and the type of the protective film, and the absolute value of the transmittance of the illuminance-corrected monomer fluctuates from the difference in the reflectance of the interface. However, in the present invention, it is important that the opacity of the two polarizing sub-layers corrects the difference in transmittance of the monomer, and the fluctuation of the absolute value is not important. In other words, if the difference between the two is measured under the same configuration, the difference between the transmittances of the two polarizing sublayers can be regarded as the difference between the transmittances of the two polarizing sublayers.

[dyeing step, crosslinking step, washing step]

Fig. 3 is a schematic cross-sectional view showing an example of a method for treating a stretched film of the dyeing step, the crosslinking step, and the washing step of the present invention. The dyeing tank 10 for holding the dyeing solution, the crosslinking tank 20 for holding the crosslinking solution, and the washing tank 30 for holding the cleaning liquid are sequentially arranged, and the two-layer film 202 is introduced into the dyeing tank 10 through the guide roll 101, and is disposed in the dyeing tank 10 The plurality of guide rolls in the dyeing tank 10 are conveyed in the dyeing tank 10 (in the dyeing solution), and then introduced into the crosslinking tank 20 by the guide rolls 102, and are in contact with the plurality of guide rolls disposed in the crosslinking tank 20. Coupling 20 (in the cross-linking solution) The conveyance roller 103 is introduced into the cleaning tank 30 by the guide roller 103, and is conveyed in the cleaning tank 30 (in the cleaning liquid) while being in contact with the plurality of guide rollers disposed in the cleaning tank 30, and then conveyed to the lower side by the guide roller 104. One step.

[Method for adjusting contact time of polyvinyl alcohol-based resin layer to dyeing solution]

Hereinafter, a specific method of adjusting the contact time of the first polyvinyl alcohol-based resin layer 21 and the second polyvinyl alcohol-based resin layer 22 of the two-area layer film 202 with respect to the dyeing solution will be described.

(First embodiment)

Fig. 4 is a schematic cross-sectional view showing the dyeing tank of the first embodiment. In the dyeing tank 10, five guide rolls having substantially equal diameters are disposed, and on the lower side, three guide rolls 11A, 12A, and 13A are disposed at approximately equal intervals, and on the upper side, two guide rolls 11B, 12B are disposed at approximately equal intervals. . The two-area layer film 202 is introduced into the dyeing tank 10 to be in contact with the dyeing solution, and is conveyed in the dyeing solution so as to alternately contact the lower guide roller and the upper guide roller. More specifically, it is first contacted below the lower guide roller 11A, and then above the upper guide roller 11B, below the lower guide roller 12A, above the upper guide roller 12B, and on the lower side. The guide rollers 13A are sequentially contacted and then conveyed outside the dyeing tank 10. In Fig. 4, the contact portion of each of the guide rolls and the two-area layer film 202 is indicated by a broken line.

The first polyvinyl alcohol-based resin layer 21 is formed on the surface of one side of the two-layer film 202, and the second polyvinyl alcohol-based resin layer 22 is formed on the other surface. The first polyvinyl alcohol-based resin layer 21 and the second polyvinyl alcohol-based resin layer 22 may be either the upper side or the lower side, and the first polyvinyl alcohol-based resin may be used here. The layer 21 is above, and the second polyvinyl alcohol-based resin layer 22 is Explain the situation below.

As is apparent from Fig. 4, the two-area layer film 202 is attached to the lower guide rolls 11A, 12A, and 13A, and is in contact with the first polyvinyl alcohol-based resin layer 21 above the two-area layer film 202, and on the upper guide roll 11B. And 12B, the second polyvinyl alcohol-based resin layer 22 which is in contact with the lower layer film 202 is transferred and transferred.

When the first polyvinyl alcohol-based resin layer 21 or the second polyvinyl alcohol-based resin layer 22 is in contact with the guide roller in the dyeing tank 10, it is considered that the first polyvinyl alcohol-based resin layer 21 and the first polyvinyl alcohol-based resin layer 21 are not in contact with the dyeing solution. The contact time of the polyvinyl alcohol-based resin layer 22 with the dyeing solution can be adjusted by changing the contact time with the guide roller. In other words, the time T1 at which the first polyvinyl alcohol-based resin layer 21 contacts the dyeing solution is reduced from the immersion time of the two-area layer film 202 in the dyeing solution by the first polyvinyl alcohol-based resin layer 21 to the guide rolls 11A and 12A, The time T2 of the contact time of the 13A, the time T2 at which the second polyvinyl alcohol-based resin layer 22 contacts the dyeing solution is changed from the immersion time of the two-area layer film 202 in the dyeing solution minus the second polyvinyl alcohol-based resin layer 22 to the guide roller. 11B, 12B contact time time. Further, the contact time of the first polyvinyl alcohol-based resin layer 21 or the second polyvinyl alcohol-based resin layer 22 with the guide roller can be calculated or measured by the distance of the contact portion, and the distance can be divided by the transfer speed. Calculated.

According to the arrangement of the guide rolls in the dyeing tank 10 shown in Fig. 4, the lower guide roller is one more than the upper guide roller, and the first polyvinyl alcohol-based resin layer 21 can be easily brought into contact with the guide roller and the second time. The time at which the polyvinyl alcohol-based resin layer 22 contacts the guide roller is designed to have a desired difference, and the ratio (%) of the contact time difference shown in the formula (1) is adjusted to be more than 4% in absolute value.

Example [Example 1]

Two polarizing plates 501a and 501b are produced from the double-sided polarizing laminated film 302 in the flowchart shown in Fig. 2 .

(substrate film)

Propylene is disposed on both sides of a resin layer composed of a propylene/ethylene random copolymer (Sumitomo NOBLEN W151 manufactured by Sumitomo Chemical Co., Ltd., melting point Tm = 138 ° C) containing about 5% by weight of an ethylene unit. The base film 1 having a three-layer structure of a resin layer composed of a homopolymer polypropylene (Sumitomo NOBLEN FLX80E4 manufactured by Sumitomo Chemical Co., Ltd., melting point Tm = 163 ° C) was used by using a multilayer extrusion molding machine. It is produced by extrusion molding. The total thickness of the obtained base film 1 was 90 μm, and the thickness ratio of each layer (FLX80E4/W151/FLX80E4) was 3/4/3.

(undercoat layer forming step)

A polyvinyl alcohol powder (trade name: Z-200, manufactured by Nippon Synthetic Chemical Co., Ltd., average polymerization degree 1100, average saponification degree: 99.5 mol%) was dissolved in hot water at 95 ° C to prepare an aqueous solution having a concentration of 3 wt%. . In the obtained aqueous solution, 5 parts by weight of a crosslinking agent (manufactured by Tajika Chemical Industry Co., Ltd., trade name: SUMIREZ RESIN 650) was mixed with 6 parts by weight of the polyvinyl alcohol powder to obtain a primer solution. The surface of one side of the base film 1 was subjected to corona treatment, and the undercoat solution was applied using a micro gravure coater, and dried at 80 ° C for 10 minutes to form an undercoat layer having a thickness of 0.2 μm.

Further, the surface of the other side of the base film 1 was subjected to corona treatment, and the same undercoating solution was applied to form a film having an undercoat layer formed on both surfaces of the base film 1.

(Resin layer forming step)

Polyvinyl alcohol powder (trade name: PVA124, manufactured by Kuraray Co., Ltd., The average degree of polymerization (2400, average saponification degree: 98.0 to 99.0 mol%) was dissolved in hot water at 95 ° C to prepare a polyvinyl alcohol aqueous solution having a concentration of 8 wt%. Using a lip coater, the obtained aqueous solution is coated on the surface of one side of the substrate film 1 to form a surface of the undercoat layer, continuously at 80 ° C for 2 minutes, at 70 ° C for 2 minutes, at 60 ° C for Drying was carried out for 4 minutes to prepare a two-layer single-area layer film 201 composed of the base film 1 and the first polyvinyl alcohol-based resin layer 21.

Further, a surface of the undercoat layer is formed on the other surface of the base film 1, and the same coating treatment is performed to prepare the first polyvinyl alcohol-based resin layer 21, the base film 1, and the second polyethylene. The two-area layer film 202 composed of the alcohol-based resin layer 22. The thickness of the polyvinyl alcohol-based resin layers 21 and 22 at this time (before stretching) was 10.5 μm and 10.2 μm, respectively.

(extension step)

For the two-area film 202, a free end-axis extension of 5.8 times was carried out at 160 ° C using a roll longitudinal stretching machine. The thickness of the two polyvinyl alcohol-based resin layers of the two-layer film after stretching was 5 μm ± 0.1 μm.

(staining step)

The stretched two-layer film was immersed in a dye solution of a mixed aqueous solution of iodine and potassium iodide at 30 ° C to carry out a dyeing treatment. At this time, in the dyeing tank, a guide roller in the dyeing tank as shown in Fig. 4 is disposed, and the following is set: the total retention length of the two-layer film in the dyeing solution: 4700 mm

Transmission speed: 1.78m/min

Total residence time of the two-layer film in the dyeing solution: 4.7 m / [(1.78 / 60) m / sec] ≒ 158.427 sec

Guide roller diameter: 125mm

The length of the first polyvinyl alcohol-based resin layer 21 contacting the lower guide rolls 11A, 12A, and 13A, and the length of the second polyvinyl alcohol-based resin layer 22 contacting the upper guide rolls 11B and 12B are adjusted to design a path. The time of the contact guide roller is calculated as the value described in the field of "contact time to the guide roller" in Table 1. The time of contact with the dye solution is calculated as the "contact time to the dye solution" in Table 1. Value.

Then, the excess iodine solution was washed with pure water at 10 °C. Then, a crosslinking solution of a mixed aqueous solution of boric acid and potassium iodide at 76 ° C was immersed for 600 seconds. Further, the mixing ratio of the dyeing solution and the crosslinking solution is as follows.

<staining solution>

Water: 100 parts by weight

Iodine: 0.35 parts by weight

Potassium iodide: 10 parts by weight

<Crosslinking solution>

Water: 100 parts by weight

Boric acid: 9.5 parts by weight

Potassium iodide: 5 parts by weight

(washing step)

Then, the two-layer film was washed with pure water at 10 ° C for 4 seconds, and finally dried at 80 ° C for 300 seconds. By the above steps, the double-sided polarizing laminated film 302 in which the polyvinyl alcohol-based resin layers 21 and 22 are formed as the polarizing sub-layers 31 and 32 on both surfaces of the base film 1 is obtained.

(Protective film bonding step)

Polyvinyl alcohol powder (manufactured by Kuraray Co., Ltd., average polymerization degree 1800, Trade name: KL-318) Dissolved in hot water at 95 ° C to prepare an aqueous solution having a concentration of 3% by weight. In the obtained aqueous solution, 1 part by weight of a crosslinking agent (manufactured by Tajika Chemical Industry Co., Ltd., trade name: SUMIREZ RESIN 650) was mixed with 2 parts by weight of the polyvinyl alcohol powder to obtain an adhesive solution. After applying the adhesive solution to both surfaces of the two-sided polarizing laminate film obtained above, a protective film (TAC: KC4UY) 41 and 42 manufactured by Konica Minolta Optical Co., Ltd. was attached to both sides at 80 ° C. After drying for 5 minutes, a double-sided bonding film 402 composed of five layers of the protective film 41, the polarizing sub-layer 31, the base film 1, the polarizing sub-layer 32, and the protective film 42 was obtained.

(drying step and stripping step)

The first polarizing plate 501a composed of the polarizing sub-layer 32 and the protective film 42 is peeled off from the double-sided bonding film 402. The base film 1 is peeled off from the remaining film (the film formed of the base film 1, the polarizing layer 32, and the protective film 42), and the second polarizing plate 501b composed of the polarizing layer 32 and the protective film 42 is obtained.

The base film 1 is easily peeled off from the polarizing plates 501a and 501b formed on both surfaces thereof. The thicknesses of the polarizing sub-layers 31 and 32 of the two polarizing plates 501a and 501b obtained were all 5 μm ± 0.1 μm.

[Embodiment 2]

Two polarizing plates 501a and 501b are produced from the double-sided polarizing laminated film 302 in the flowchart shown in Fig. 2 . Example 2 is the same as Example 1, except that the path of the dyeing step is different, and this point will be described below.

In the dyeing tank of the dyeing step of Example 2, the guide rolls in the dyeing tank as shown in Fig. 4 were placed and set as follows: the total residence length of the two-layer film in the dyeing solution: 4700 mm

Transmission speed: 1.78m/min

Total residence time of the two-layer film in the dyeing solution: 4.7 m / [(1.78 / 60) m / sec] ≒ 158.427 sec

Guide roller diameter: 200mm

The length of the first polyvinyl alcohol-based resin layer 21 contacting the lower guide rolls 11A, 12A, and 13A, and the length of the second polyvinyl alcohol-based resin layer 22 contacting the upper guide rolls 11B and 12B are adjusted to design a path. The time of the contact guide roller is calculated as the value described in the field of "contact time to the guide roller" in Table 1. The time of contact with the dye solution is calculated as the "contact time to the dye solution" in Table 1. Value.

[Determination of Polarization Performance of Polarizing Plate]

The polarizing performance of the polarizing plate obtained in the examples was measured using a spectrophotometer (V7100) manufactured by JASCO Corporation. At the time of measurement, the incident direction of light is from the side of the polarizing sublayer. The average value of the transmittance correction single transmittance (Ty) and the difference between the average values of the transmittance correction single transmittances of the two polarizing plates 501a and 501b are shown in Table 1. In addition, the average value of the transmittance of the two polarizing plates was corrected, and the effective width of the film in the width direction was divided into 11 parts for the respective polarizing plates, and the value measured for the 11 points was divided. average value. Further, since the same protective film is used for the two polarizing plates, there is no difference in the transmittance of the single body. Therefore, the difference in the average value of the transmittance of the polarizing plate for the single transmittance (Ty) can be regarded as the visual sensitivity of the polarizing layer. The difference between the average values of the monomer transmittances (Ty) was corrected.

From the results shown in Table 1, the ratio of the contact time difference to the dyeing solution (the value of the column (T1-T2)/{(T1+T2)/2} x 100 (%) in Table 1) is calculated in absolute value. When the amount is more than 4% (Examples 1 and 2), the difference in the transmittance of the sensibility-corrected monomer expressed in % units of the two polarizing plates exceeds 0.3, and two polarizing plates having a large difference in transmittance can be obtained at the same time.

(industrial use possibility)

According to the polarizing laminated film produced by the method of the present invention, two polarizing sublayers having different transmittances can be simultaneously obtained, or two polarizing plates having different transmittances can be simultaneously obtained.

1‧‧‧Base film

21‧‧‧1st polyvinyl alcohol resin layer

22‧‧‧2nd polyvinyl alcohol resin layer

31, 32‧‧‧ polarized sublayer

41, 42‧‧‧ protective film

201‧‧‧Single-layer film

202‧‧‧Two-layer film

302‧‧‧Two-sided polarizing laminated film

402‧‧‧Two-sided film

501a, 501b‧‧‧ polarizing plate

Claims (9)

A method for producing a polarizing laminated film, comprising: a base film; and a method for producing a polarizing laminated film formed on each of two polarizing layer layers on both surfaces of the base film, comprising the following steps: a first polyvinyl alcohol-based resin layer on one surface, a second polyvinyl alcohol-based resin layer on the other surface, a resin layer forming step of obtaining a laminated film, and an extending step of extending the laminated film; The first polyvinyl alcohol-based resin layer and the second polyvinyl alcohol-based resin layer of the laminated film after the contact are brought into contact with a dye solution containing a dichroic dye, and dyed by the dichroic dye to form two polarized lights. a dyeing step of the sub-layer; wherein, in the dyeing step, the time during which the first polyvinyl alcohol-based resin layer contacts the dyeing solution is T1, and the time when the second polyvinyl alcohol-based resin layer contacts the dyeing solution is T2 The ratio of the contact time difference calculated from the ratio (%) of the contact time difference = (T1 - T2) / {(T1 + T2) / 2} x 100 is calculated by the absolute value to exceed 4%. The method for producing a polarizing laminated film according to claim 1, wherein the ratio of the contact time difference is 4.5% or more in absolute value. The method for producing a polarizing laminate film according to the first or second aspect, wherein the dyeing step is to contact the first polyvinyl alcohol-based resin layer and/or the second polyvinyl alcohol-based resin layer. The guide roll conveys the laminated film in the dyeing solution, and adjusts the time during which the first polyvinyl alcohol-based resin layer and the second polyvinyl alcohol-based resin layer are in contact with the guide roller, and adjusts the first polyvinyl alcohol-based resin. Floor The time T1 at which the dyeing solution is contacted and the time T2 at which the second polyvinyl alcohol-based resin layer contacts the dyeing solution are such that the ratio of the contact time difference becomes a desired numerical range. The method for producing a polarizing laminate film according to any one of the first to third aspect of the present invention, wherein after the dyeing step, the surface of the protective film is bonded to the surface of at least one of the polarizing sublayers Step by step. The method for producing a polarizing laminate film according to the fourth aspect of the invention, wherein the protective film is bonded to the surfaces of the two polarizing sublayers in the bonding step. A method for producing a polarizing plate, comprising: a method of producing a polarizing plate comprising a polarizing layer and a protective film, comprising: a step of preparing a polarizing laminated film obtained by the manufacturing method according to claim 4 or 5 And a layered body of the polarizing layer of the polarizing laminate film and the protective layer, which is peeled off from the base film to obtain a polarizing plate. A polarizing laminated film comprising: a base film; and two polarizing sub-layers formed on both surfaces of the base film; wherein the average of the transmittance-corrected single transmittance of the two polarizing sub-layers expressed in % units The difference in values exceeds 0.3 points. The polarizing laminate film according to the seventh aspect of the invention, wherein the difference between the average values of the transmittances of the sensibility-corrected monomers expressed in % units of the two polarizing sub-layers is 0.45 or more. A polarizing plate set is a polarizing plate set formed by two polarizing plates disposed on two sides of a liquid crystal unit used in a liquid crystal display device, The two polarizing plates each include one of the two polarizing sublayers of the polarizing laminated film according to claim 7 of the patent application.