TW201343370A - Manufacturing method of polarizing plate - Google Patents

Abstract

This invention provides a manufacturing method of polarizing plate, including: a resin layer forming step which forms a polyvinyl alcohol-based resin layer 2 on at least one surface of a base film 1, so as to obtain a laminated film 3; an extending step which uniaxially extends the laminated film 3 such that the resin layer 2 having a thickness of 10 μ m or less, so as to obtain a stretched film 4; a dying step which forms a polarizing layer 5 by dying the stretched film 4 with a dichroic dye, so as to obtain a polarizing laminated film 6; a moisture-proof layer forming step which forms a moisture-proof layer 7 on a surface of the polarizing layer 5 opposite to the base film 1 in the polarizing laminated film 6, with a moisture permeability of 200g/m<SP>2</SP>/24hrs or less, an in-plane phase difference of 100nm or more, and an angle θ of a delay phase axis to an absorption axis of the polarizing layer 5 of 20 degrees or more and 70 degrees or less, so as to obtain a multilayer film 8; and a stripping step which strips the base film 1 from the multilayer film 8.

Description

Polarizing plate manufacturing method

The present invention relates to a method of manufacturing a polarizing plate. Further, a polarizing plate with an adhesive layer provided with an adhesive layer on the polarizing plate, and an image display device using the same.

In a video display device such as a liquid crystal display device or an organic EL display device, a circularly polarizing plate is provided on the viewing side in order to prevent reflection of external light. The circular polarizing plate has a retardation layer such as a polarizing sub-layer and a quarter-wave plate, and light incident on the image display device from outside is circularly polarized, thereby preventing light from being emitted outside the device, and as a result, external light can be prevented. Since the reflection is performed, the phase difference layer is usually disposed inside the image display device.

In recent years, the mobile liquid crystal display device such as the video display device, the notebook personal computer, and the mobile phone has been reduced in size and weight, and the polarizing plate (circular polarizing plate, linear polarizing plate) used in the liquid crystal display device is also required. Further, it is required to be thinner and lighter. Further, in order to use a liquid crystal display device in a high-temperature, high-humidity environment, heat resistance and moisture resistance of the polarizing plate are required.

On the other hand, in an environment where the sun is strong outside, in order to eliminate the glare, the liquid crystal display is observed in the state of wearing polarized sunglasses. Display device. The light emitted from the liquid crystal display device is generally linearly polarized, and when the liquid crystal display device is viewed in a state in which polarized sunglasses are worn, the angle between the absorption axis of the polarized sunglasses and the polarized axis of the linearly polarized light of the liquid crystal display device is There are problems that create visibility.

In such a case, as a method of producing a thin polarizing plate, Patent Document 1 discloses that a polyvinyl alcohol-based resin layer is formed on one surface of a base film, and then stretched, and then the polyvinyl alcohol-based resin layer is opposite to the base film. After the side surface is bonded to the triacetonitrile cellulose film, the substrate film is peeled off and a dyeing treatment is performed. Further, in Patent Document 2, a polyvinyl alcohol-based resin layer is formed on one surface of a base film composed of an acrylic resin or a cyclic olefin resin, and then stretched, and then subjected to a dyeing treatment to thereby produce the substrate. A method in which a film has a polarizing plate of a protective film. Patent Document 3 discloses that a quarter-wavelength plate is provided on one surface (image display unit side) of the thinned polarizing sub-layer, and an easy-adhesive layer, a protective layer, and a phase difference layer are sequentially provided on the other surface (viewing side). Polarizer.

Patent Document 1: Japanese Patent Laid-Open Publication No. 2000-338329

Patent Document 2: Japanese Patent Laid-Open Publication No. 2009-98653

Patent Document 3: Japanese Patent No. 4804589

The polarizing plate obtained by the methods described in Patent Documents 1 to 3 is not necessarily sufficient in terms of heat resistance and moisture resistance at high temperatures and high humidity, and visibility when polarized sunglasses are worn. Further, as described in Patent Document 3 The circular polarizing plate has a large number of layers and is a thick polarizing plate.

Therefore, an object of the present invention is to provide a method for producing a thin polarizing plate which is excellent in heat resistance and moisture resistance under high temperature and high humidity and which is excellent in visibility when wearing polarized sunglasses. Further, another object of the present invention is to provide a circularly polarizing plate which is excellent in heat resistance and moisture resistance under high temperature and high humidity while suppressing the total number of layers and thickness and ensuring visibility when polarized sunglasses are worn.

The present invention encompasses the following.

[1] The method for producing a polarizing plate, comprising: a resin layer forming step of forming a polyvinyl alcohol-based resin layer on at least one surface of the base film to obtain a laminated film; and an extending step of performing the laminated film The uniaxially extending to the polyvinyl alcohol-based resin layer has a thickness of 10 μm or less to obtain a stretched film; and the dyeing step is performed by dyeing the stretched film with a dichroic dye to form a polarizing layer to obtain a polarizing laminated film; a moisture-proof layer forming step in which the in-plane phase difference of a moisture permeability of 200 g/m ² /24 hrs or less is formed on a surface of the polarizing sub-layer opposite to the base film. a moisture barrier layer having an angle θ of 100 nm or more and a retardation axis with respect to an absorption axis of the polarizing sublayer of 20 degrees or more and 70 degrees or less, and a multi-layer film; and a peeling step of peeling off the substrate from the multilayer film film.

[2] The method for producing a polarizing plate according to [1], wherein in the moisture-proof layer forming step, the polarizing sub-layer is opposite to the substrate film On the surface, a moisture-proof layer is formed through a photocurable adhesive layer.

[3] The method for producing a polarizing plate according to the above aspect, wherein in the moisture-proof layer forming step, the surface of the polarizing layer is opposite to the substrate film. a retardation film having an in-plane phase difference of 200 g/m ² /24 hrs or less and having a phase difference of 100 nm or more, and an angle θ of the slow axis with respect to the absorption axis of the polarizing sublayer is 20 degrees or more and 70 degrees or less. .

The method for producing a polarizing plate according to any one of the above aspects, wherein the retardation film is surface-treated on a surface opposite to a bonding surface of the polarizing sub-layer. .

[5] A polarizing plate with an adhesive layer, comprising: a polarizing plate manufactured by the method for producing a polarizing plate according to any one of [1] to [4]; and a polarizing plate disposed on the polarizing plate An adhesive layer on a surface of the polarizing layer opposite to the moisture-proof layer.

[6] An image display device comprising: a polarizing plate with an adhesive layer as described in [5]; and an image display unit attached to an adhesive layer side of the polarizing plate.

[7] A circularly polarizing plate comprising: a polarizing plate with an adhesive layer as described in [5]; and a retardation layer attached to the side of the adhesive layer of the polarizing plate.

[8] A circularly polarizing plate with an adhesive layer, comprising: the circularly polarizing plate according to [7]; and a surface provided on a side opposite to the moisture-proof layer of the polarizing sub-layer of the circular polarizing plate Adhesive layer.

[9] An image display device comprising: a circularly polarizing plate with an adhesive layer as described in [8]; and an image display unit attached to an adhesive layer side of the circular polarizing plate.

[10] A method for producing a circularly polarizing plate, comprising: a resin layer forming step of forming a polyvinyl alcohol-based resin layer on at least one side of a base film to obtain a laminated film; and an extending step of performing the laminated film The axis extends to a thickness of the polyvinyl alcohol-based resin layer of 10 μm or less to obtain a stretched film; and the dyeing step is performed by dyeing the stretched film with a dichroic dye to form a polarizing layer to obtain a polarizing laminated film; The wet layer forming step is formed on the surface of the polarizing layer that is opposite to the base film by a light-curable adhesive layer to form a moisture permeability of 200 g/m ² / 24 hrs or less, the in-plane phase difference is 100 nm or more, and the angle θ of the slow phase axis with respect to the absorption axis of the polarizing sub-layer is 20 degrees or more and 70 degrees or less, and the multi-layer film; the peeling step is The multilayer film is peeled off from the base film to obtain a polarizing film with a moisture-proof layer; and a retardation layer forming step is provided in the polarizing film with the moisture-proof layer, the polarizing layer and the moisture-proof layer. phase Forming the retardation layer side.

According to the present invention, it is possible to provide a method for producing a thin polarizing plate which is excellent in heat resistance and moisture resistance under high temperature and high humidity and which is excellent in visibility when wearing polarized sunglasses. Further, an adhesive layer may be provided on the polarizing plate obtained by the method to form a polarizing plate with an adhesive layer, and the image display device may be attached to the image display panel via the adhesive layer. Then, the polarizing plate with the pressure-sensitive adhesive layer and the retardation layer are bonded to each other via the pressure-sensitive adhesive layer, whereby the total number of layers and the thickness can be suppressed, and the visibility when the polarized sunglasses are worn can be ensured, and the high temperature is high. A circular polarizer that is excellent in heat resistance and moisture resistance under wet conditions. Further, an adhesive layer may be provided on the circular polarizing plate to form a circularly polarizing plate with an adhesive layer, and the image display device may be attached to the image display panel via the adhesive layer.

1‧‧‧Substrate film

2‧‧‧Polyvinyl alcohol resin layer

3‧‧‧ laminated film

4‧‧‧Extended film

5‧‧‧ polarized sublayer

5a‧‧‧Absorption axis

6‧‧‧Polarized laminated film

7‧‧‧Wetproof layer

7a‧‧‧late phase axis

8‧‧‧Multilayer film

9, 9b‧‧‧ polarizing plate

10‧‧‧ adhesive layer

11, 11b, 11c‧‧‧ adhesive layer

12‧‧‧Image display unit

13, 13b‧‧‧ phase difference layer

20‧‧‧Polarizer with adhesive layer

30‧‧‧Image display device

40‧‧‧round polarizing plate

50‧‧‧Polar polarizer with adhesive layer

Fig. 1 (A) to (E) are schematic views showing a cross section of a film obtained in each step of the production method of the present invention.

Fig. 2 (A) and (B) are conceptual diagrams showing the relationship between the slow axis of the moisture-proof layer and the absorption axis of the polarizing sub-layer.

Fig. 3 is a conceptual diagram showing an example of a cross section of a polarizing plate obtained by the production method of the present invention.

Fig. 4 is a conceptual diagram showing an example of a cross section of a polarizing plate obtained by the production method of the present invention.

Figure 5 is a cross-sectional view showing a polarizing plate with an adhesive layer of the present invention. A conceptual diagram of an example.

Fig. 6 is a conceptual diagram showing an example of a cross section of the video display device of the present invention.

Fig. 7 is a conceptual diagram showing an example of a cross section of a circularly polarizing plate of the present invention.

Fig. 8 is a conceptual view showing an example of a cross section of a circularly polarizing plate of the present invention.

Fig. 9 is a conceptual view showing an example of a cross section of a circularly polarizing plate with an adhesive layer of the present invention.

Fig. 10 is a conceptual view showing an example of a cross section of a circularly polarizing plate with an adhesive layer of the present invention.

Fig. 11 is a conceptual diagram showing an example of a cross section of the video display device of the present invention.

Fig. 12 is a conceptual diagram showing an example of a cross section of the video display device of the present invention.

<Method of Manufacturing Polarizing Plate>

A method for producing a polarizing plate according to the present invention includes a resin layer forming step (S10) of forming a polyvinyl alcohol-based resin layer on at least one surface of a base film to obtain a laminated film; and an extending step (S20) of uniaxially extending The laminated film has a thickness of the polyvinyl alcohol-based resin layer of 10 μm or less to obtain a stretched film, and a dyeing step (S30) of dyeing the stretched film with a dichroic dye to form a polarizing layer to obtain a polarized light. a moisture-repellent layer forming step (S40), wherein a moisture-proof layer is formed on a surface of the polarizing sub-layer opposite to the substrate film to obtain a multilayer film; and a peeling step (S50), the base film is peeled off from the multilayer film. Fig. 1 is a schematic view showing a cross section of a film obtained in each step, and the manufacturing method of the present invention will be described in detail below with reference to Fig. 1 .

[Resin layer forming step (S10)]

In the resin layer forming step, the polyvinyl alcohol-based resin layer 2 is formed on at least one surface of the base film 1, and the laminated film 3 is obtained (Fig. 1(A)).

(substrate film)

As the resin used for the base film 1, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, and elongation can be used, and an appropriate resin can be selected depending on the Tg or Tm. Specific examples of the thermoplastic resin include a polyolefin resin such as a chain polyolefin resin or a cyclic polyolefin resin, a polyester resin, a (meth)acrylic resin, a cellulose ester resin, and a polycarbonate. Ester resin, polyvinyl alcohol resin, vinyl acetate resin, polyacrylate resin, polystyrene resin, polyether oxime resin, polyfluorene resin, polyamine resin, polyimine Resins and mixtures, copolymers, and the like.

The base film 1 may be a single layer or a plurality of layers composed of the above resin.

The chain-like polyolefin-based resin is preferably polyethylene, polypropylene, or the like from the viewpoint of stably extending at a high magnification. Further, an ethylene-propylene copolymer or the like obtained by copolymerizing ethylene and propylene can also be suitably used. Total The polymerization may be another type of monomer, and other types of monomers copolymerizable with propylene may, for example, be ethylene or an α-olefin. The α-olefin is preferably an α-olefin having 4 or more carbon atoms, and more preferably an α-olefin having 4 to 10 carbon atoms. Specific examples of the α-olefin having 4 to 10 carbon atoms include a linear single such as 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, and 1-decene. An olefin; a branched monoolefin such as 3-methyl-1-butene, 3-methyl-1-pentene or 4-methyl-1-pentene; vinylcyclohexane or the like. The copolymer of propylene and other monomers copolymerizable therewith may be a random copolymer or a block copolymer. The content ratio of the constituent units derived from the other monomers in the copolymer can be determined by infrared (IR) spectroscopy according to the method described in the "Handbook of Polymer Analysis" (1995, issued by Kiyoshiya Shoten) on page 616. .

Among the above, the propylene-based resin constituting the propylene-based resin film is preferably a homopolymer of propylene, a propylene-ethylene random copolymer, a propylene-1-butene random copolymer, and propylene-ethylene-1-butene. Copolymer.

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

The cyclic polyolefin resin is preferably a norbornene resin. The cyclic polyolefin-based resin is a resin which is polymerized by a cyclic olefin as a polymerization unit. For example, the resin described in JP-A No. 1-240517, JP-A No. 3-148882, and JP-A No. 3-122137 . Specific examples include ring opening of a cyclic olefin (total) a polymer, an addition polymer of a cyclic olefin, a copolymer of a cyclic olefin and an α-olefin of ethylene or propylene (represented as a random copolymer), and the modification with an unsaturated carboxylic acid or a derivative thereof Graft copolymers, and such hydrides and the like. Specific examples of the cyclic olefin include a norbornene-based monomer.

There are various commercially available products of the cyclic polyolefin resin. Specific examples include Topas (registered trademark) (manufactured by Ticona Co., Ltd.), Arton (registered trademark) (manufactured by JSR Co., Ltd.), ZEONOR (registered trademark) (manufactured by Zeon Co., Ltd.), and ZEONEX (registered trademark) (Japan) Zeon Co., Ltd., APL (registered trademark) (manufactured by Mitsui Chemicals, Inc.), etc.

The polyester resin is a polymer having an ester bond, and is mainly a polycondensate of a polyvalent carboxylic acid and a polyhydric alcohol. As the polyvalent carboxylic acid to be used, a divalent dicarboxylic acid such as terephthalic acid, isophthalic acid, dimethyl terephthalate or dimethyl naphthalene dicarboxylate is mainly used. Further, as the polyhydric alcohol to be used, a divalent diol is mainly used, and examples thereof include propylene glycol, butanediol, neopentyl glycol, and cyclohexane dimethanol.

A typical example of the polyester resin is polyethylene terephthalate in which a copolymer of terephthalic acid and ethylene glycol is used. Polyethylene terephthalate is a crystalline resin, and the state before the crystallization treatment is easily subjected to a treatment such as stretching. The crystallization treatment may be carried out by heat treatment at the time of stretching or extension as needed. Further, it is suitable to use a framework of polyethylene terephthalate to re-polymerize other kinds of monomers to thereby reduce crystallinity (or non-crystalline) copolymerized polyester. As such a resin, for example, a copolymer of cyclohexanedimethanol or isophthalic acid is preferably used. These resins have good extensibility and are suitable Used together.

Specific examples of the resin other than polyethylene terephthalate and copolymers thereof include polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, and polybutylene terephthalate. Propylene glycol, propylene naphthalate, dimethyl dimethyl terephthalate, cyclohexane dimethyl phthalate, and the like. These mixed resins and copolymers can be suitably used.

As the (meth)acrylic resin, any suitable (meth)acrylic resin can be used. For example, poly(meth) acrylate such as polymethyl methacrylate, methyl methacrylate-(meth)acrylic acid copolymer, methyl methacrylate-(meth) acrylate copolymer, methyl methacrylate - acrylate-(meth)acrylic acid copolymer, methyl (meth)acrylate-styrene copolymer (MS resin, etc.), polymer having an alicyclic hydrocarbon group (for example, methyl methacrylate-methacrylic acid ring) Hexyl ester copolymer, methyl methacrylate-methyl (meth) acrylate (meth) acrylate copolymer, etc.). More preferably, a poly(meth)acrylic acid C1-6 alkyl ester such as polymethyl methacrylate is used. More preferably, the (meth)acrylic resin is 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 the cellulose ester-based resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Further, examples of such a copolymer and a part of a hydroxyl group which are modified by other substituents may be mentioned. Among these, cellulose triacetate is particularly preferred. Cellulose triacetate has many commercial products, and it is also advantageous in terms of availability and cost. For the commercially available product of cellulose triacetate, for example, Fujitac (registered trademark) TD80 (manufactured by Fuji Film Co., Ltd.), Fujitac (registered trademark) TD80UF (manufactured by Fuji Film Co., Ltd.), Fujitac (registered trademark) TD80UZ (Fuji Film Co., Ltd.), Fujitac (registered trademark) TD40UZ (made by Fuji Film Co., Ltd.), KC8UX2M (Konica Minolta Co., Ltd.), KC4UY (Konica Minolta Co., Ltd.) Company system) and so on.

The polycarbonate resin is an engineering plastic composed of a polymer that transmits a carbonate-bonded monomer unit, and has a resin having high impact resistance, heat resistance, and flame retardancy. Moreover, due to its high transparency, it is also suitable for optical applications. For optical use, a resin called a modified polycarbonate which is a polymer skeleton for the purpose of lowering the photoelastic coefficient, a copolymerized polycarbonate having improved wavelength dependence, and the like may be commercially available. Such polycarbonate resins are widely commercially available, and include PANLITE (registered trademark) (Teijin Chemical Co., Ltd.), IUPILON (registered trademark) (Mitsubishi Engineering Plastics Co., Ltd.), and SD POLYCA (registered trademark) (Sumitomo Dow) (SUMITOMO DOW) Co., Ltd.), CALIBER (registered trademark) (Dow Chemical Co., Ltd.), etc.

In the base film 1, any suitable additive may be added in addition to the above thermoplastic resin. Examples of such additives include ultraviolet absorbers, antioxidants, slip agents, plasticizers, deamulating agents, coloring inhibitors, flame retardants, nucleating agents, antistatic agents, pigments, and color formers. The content of the above-exemplified thermoplastic resin in the base film is desirably from 50 to 100% by weight, more desirably from 50 to 99% by weight, still more preferably from 60 to 98% by weight. % is particularly preferably from 70 to 97% by weight. When the content of the thermoplastic resin in the base film is less than 50% by weight, the high transparency and the like which the thermoplastic resin originally has may not be sufficiently found.

The thickness of the base film 1 can be appropriately determined, and is preferably from 1 to 500 μm , more preferably from 1 to 300 μm , still more preferably from 5 to 200 μm , from the viewpoint of workability such as strength and usability. The thickness of the substrate film is most preferably from 5 to 150 μm .

In order to improve the adhesion to the resin layer 2, the base film 1 can be subjected to corona treatment, plasma treatment, flame treatment, or the like at least on the surface on the side where the resin layer 2 is formed. Further, in order to improve the adhesion, a thin layer such as an undercoat layer or an adhesive layer can be formed on the surface of the base film 1 on the side of the resin layer 2 side. Here, the base film 1 herein does not include an adhesive layer, a corona treatment layer, or the like.

(polyvinyl alcohol resin layer)

The polyvinyl alcohol-based resin layer 2 is typically obtained by dissolving a powder of a polyvinyl alcohol-based resin in a solvent having a high solubility such as water to obtain a polyvinyl alcohol-based resin solution, and applying the polyvinyl alcohol-based resin solution to a base film. On the surface of one side, the solvent is evaporated and dried, thereby being formed. It is possible to form a thin resin layer by forming the resin layer in this manner. The method of applying a polyvinyl alcohol-based resin solution to a base film can be carried out by a roll coating method such as a bar coating method, a reverse coating method, or a gravure coating method, a die coating method, or a slanting wheel coating. Conventional methods such as a method, a lip-mouth coating method, a spin coating method, a screen coating method, a spray coating method, a dip coating method, and a spray coating method are appropriately selected and used. The drying temperature is, for example, 50 to 200 ° C, preferably 60 to 150 ° C. Drying time If it is 2 to 20 minutes.

The thickness of the formed resin layer 2 is desirably more than 3 μm and 30 μm or less, more preferably 5 to 20 μm . If it is 3 μm or less, it becomes too thin after stretching, and the dyeability is remarkably deteriorated. When the thickness exceeds 30 μm , the thickness of the resulting polarizing layer is more than 10 μm .

In order to improve the adhesion between the base film 1 and the polyvinyl alcohol-based resin layer 2, an undercoat layer may be provided between the base film 1 and the resin layer 2. The undercoat layer is preferably formed of a composition containing a crosslinking agent or the like in the polyvinyl alcohol-based resin from the viewpoint of adhesion.

As the polyvinyl alcohol-based resin, those obtained by saponifying a polyvinyl acetate-based resin can be used. Polyvinyl acetate-based resin In addition to polyvinyl acetate of a homopolymer of vinyl acetate, for example, a copolymer of vinyl acetate and another monomer copolymerizable therewith. Examples of the other monomer copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

The polyvinyl alcohol-based resin is preferably one having a high degree of saponification. The degree of saponification is preferably in the range of from 80.0 mol% to 100.0 mol%, more desirably from 90.0 mol% to 99.5 mol%, and most desirably from 94.0 mol% to 99.0 mol%. When the degree of saponification is less than 80.0 mol%, the water resistance and moist heat resistance of the obtained polarizing layer may be lowered. Further, when the degree of saponification is too high, the dyeing speed is slow, and there is a case where a polarizing laminated film having sufficient polarizing performance cannot be obtained.

Here, the degree of saponification means that the acetic acid group contained in the polyvinyl acetate-based resin of the raw material of the polyvinyl alcohol-based resin is converted into a hydroxyl group by a saponification step. The ratio of the base, expressed as a unit ratio (% by mole), is a value defined by the following formula. It can be obtained according to the method specified in JIS K 6726 (1994).

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 higher the ratio of the hydroxyl group, that is, the lower the proportion of the acetate group which hinders crystallization.

The polyvinyl alcohol-based resin may be a partially modified modified polyvinyl alcohol. For example, the polyvinyl alcohol resin is modified by an olefin such as ethylene or propylene, an unsaturated carboxylic acid such as acrylic acid, methacrylic acid or crotonic acid, an alkyl ester of an unsaturated carboxylic acid or acrylamide. The proportion of modification is desirably less than 30 mol%, more desirably less than 10%. In the case where the modification exceeds 30 mol%, the adsorption of the dichroic dye becomes difficult, and the polarizing performance may be lowered.

The average degree of polymerization of the vinyl alcohol-based resin is not particularly limited, but is preferably 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 a value obtained by a method defined in JIS K 6726 (1994).

The polyvinyl alcohol-based resin having such characteristics is, 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%), etc.; for example, AH-26 (saponification degree: 97.0 to 98.8 mol%), AH-22, manufactured by Nippon Synthetic Chemical Co., Ltd. (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%) Etc.; for example, JC-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%) of Japan VAM & POVAL Co., Ltd. %), 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 (degree of saponification: 98.0 to 99.0 mol%) or the like can be suitably used in the present invention.

[Extension step (S20)]

In the stretching step, the laminated film 3 is uniaxially stretched to a thickness of 10 μm or less of the polyvinyl alcohol-based resin layer to obtain a stretched film 4 (Fig. 1(B)). The stretching ratio of the uniaxial stretching is desirably more than 5 times and 17 times or less, and more desirably 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 may not be sufficiently increased. On the other hand, when the stretching ratio is more than 17 times, the laminate film 3 is easily broken at the time of stretching, and the thickness of the stretched film 4 is too thin, and the workability and workability in the subsequent step are likely to be lowered. The extension processing in the extending step (S20) is not limited to the extension of one segment, and may be performed in multiple stages. At this time, the extension step after the second stage may be performed in the stretching step (S20), or may be performed simultaneously with the dyeing treatment and the crosslinking treatment in the dyeing step (S30). When such a plurality of stages of stretching are performed, the stretching process is performed in such a manner that all the stages of the stretching process are combined to have a stretching ratio of more than 5 times.

In the extending step (S20) of the present embodiment, a longitudinal stretching process in the longitudinal direction of the laminated film 3, a lateral stretching process in which the width direction is extended, and the like can be performed. The vertical extension method can be mentioned A method of extending between wheels, a method of compressing and stretching, and the like, a lateral stretching method such as a tenter method.

Further, the stretching treatment may be either a wet stretching method or a dry stretching method, but it is preferable to use a dry stretching method in which the temperature at which the laminated film 3 is stretched can be selected in a wide range.

The elongation temperature is set to be higher than the temperature at which the fluidity is exhibited to the extent that the entire polyvinyl alcohol-based resin layer 2 and the base film 1 are stretchable, and preferably -30 ° C to +30 ° C of the phase transition temperature of the base film 1 . The range is more preferably in the range of -25 ° C to + 30 ° C of the phase transition temperature of the base film 1 . When the elongation temperature is lower than the phase transition temperature of -30 ° C, it is difficult to achieve a high magnification extension of more than 5 times. When the stretching temperature exceeds the phase transition temperature + 30 ° C, the fluidity of the base film tends to be too large and the elongation tends to be difficult. Since it is easier to achieve a high-magnification extension of more than 5 times, it is preferable that the stretching temperature is within the above range, and more preferably 120 ° C or more. The extension temperature is adjusted by adjusting the temperature of the furnace.

[Staining step (S30)]

In the dyeing step, the stretched film 4 is dyed with a dichroic dye to form a polarizing layer 5, and a polarizing laminated film 6 is obtained (Fig. 1(C)). Examples of the dichroic dye include iodine, an organic dye, and the like. For the organic dye, for example, red BR, red LR, red R, pink LB, ruby red BL, red wine (bordeaux) GS, sky blue LG, lemon yellow, blue BR, blue 2R, navy blue RY, green LG can be used. , purple LB, purple B, black H, black B, black GSP, yellow 3G, yellow R, orange LR, orange 3R, scarlet GL, scarlet KGL, Congo red, bright Brilliant violet BK, super blue G, super blue GL, super orange GL, direct sky blue, direct fast orange S, long black and so on. These dichroic substances may be used alone or in combination of two or more.

The dyeing step is carried out, for example, by immersing the entire stretched film 4 in a solution (dyeing solution) containing the above-mentioned dichroic dye. As the dyeing solution, a solution in which the above dichroic dye is dissolved in a solvent can be used. The solvent of the dyeing solution is generally water, but an organic solvent compatible with water may be further added. The concentration of the dichroic dye is desirably from 0.01 to 10% by weight, more desirably from 0.02 to 7% by weight, particularly desirably from 0.025 to 5% by weight.

When iodine is used as the dichroic dye, since the dyeing efficiency can be further improved, it is preferable to further add the iodide. 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 proportion of the iodide added is preferably from 0.01 to 20% by weight in the dyeing solution. It is preferred to add potassium iodide in the iodide. When potassium iodide is added, 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 dyeing solution by the stretched film 4 is not particularly limited, and is usually in the range of 15 seconds to 15 minutes, and more preferably in the range of 30 seconds to 3 minutes. Further, the temperature of the dyeing solution is preferably in the range of 10 to 60 ° C, and more preferably in the range of 20 to 40 ° C.

Furthermore, the dyeing treatment may be carried out before or at the same time as the stretching step, in order to make the dichroic pigment adsorbed to the polyvinyl alcohol resin good. Good alignment, preferably after the extension step is performed on the unstretched film. In this case, it is possible to perform dyeing only by extending to the target magnification in advance, or to extend the method to a low target in advance in the dyeing to reach the total target magnification. Moreover, when extending in the subsequent crosslinking treatment, it is also possible to terminate at a low magnification. In this case, it is sufficient to adjust the cross-linking treatment to reach the target magnification.

In the dyeing step, cross-linking treatment can be carried out after dyeing. The crosslinking treatment can be carried out, for example, by immersing the stretched 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 used alone or in combination of two or more.

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

Iodide can be added to the crosslinking solution. By adding an iodide, the in-plane polarization characteristics of the resin layer can be more uniform. The iodide may, for example, be 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, preferably 0.5 to 8% by weight.

The immersion time of the stretched film to the crosslinking solution is usually from 15 seconds to 20 minutes, more preferably from 30 seconds to 15 minutes. Further, the temperature of the crosslinking solution is preferably in the range of 10 to 90 °C.

Furthermore, the crosslinking treatment is carried out by blending a crosslinking agent with the crosslinking agent. The color solution can be carried out simultaneously with the dyeing treatment. Further, it is possible to carry out cross-linking only if it is extended to the target magnification in advance, or to perform cross-linking processing and extension at the same time. The stretched film which has been previously extended to a low magnification in the stretching step can be stretched again in the crosslinking treatment to reach the total target magnification.

Finally, it is preferred to carry out a washing treatment and a drying treatment. The washing treatment can be carried out by washing with water. The water washing treatment is usually carried out by immersing the stretched film in pure water such as ion-exchanged water or distilled water. The water washing temperature is usually from 3 to 50 ° C, preferably from 4 ° C to 20 ° C. The immersion time is usually from 2 to 300 seconds, preferably from 3 seconds to 240 seconds.

The washing treatment may be carried out by a combination of a washing treatment of an iodide solution and a washing with water, and a solution of a liquid alcohol such as methanol, ethanol, isopropanol, butanol or propanol may be suitably used.

It is preferred to carry out a drying treatment after the washing treatment. The drying treatment may be carried out by any suitable method (for example, natural drying, air drying, and heat drying). For example, the drying temperature at the time of heat drying is usually from 20 to 95 ° C, and the drying time is usually from 1 to 15 minutes. By the above dyeing step (S30), the resin layer can function as a polarizer. In the present specification, a resin layer having a function of a polarizer is referred to as a polarizer layer, and a layered system having a polarizer layer on a base film is referred to as a polarizing laminate film.

[Wetproof layer formation step (S40)]

In the moisture-proof layer forming step, in the polarizing layer film 6 on the surface opposite to the base film 1 of the polarizing sub-layer 5, a surface having a moisture permeability of 200 g/m ² /24 hrs or less is formed. The moisture-proof layer 7 having a phase difference of 100 nm or more and an angle θ of the slow axis to the absorption axis of the polarizing sub-layer 5 is 20 degrees or more and 70 degrees or less, and a multilayer film 8 is obtained (Fig. 1 (D)). Here, the angle θ of the slow axis of the moisture-proof layer 7 with respect to the absorption axis of the polarizing sub-layer 5 will be described using FIG. 2 . Fig. 2(A) is a schematic view of the moisture-proof layer 7 and the polarizer layer 5 as viewed from the cross-sectional direction, and Fig. 2(B) shows the laminate of the moisture-proof layer 7 and the polarizer layer 5 from moisture-proof. A schematic view of the layer 7 side viewed in its normal direction. In FIGS. 2(A) and 2(B), the slow axis of the moisture-proof layer 7 is represented by 7a, and the absorption axis of the polarizing layer 5 is represented by 5a. The angle θ of the slow axis 7a of the moisture-proof layer 7 with respect to the absorption axis 5a of the polarizing sub-layer 5 means θ represented by Fig. 2(B).

The moisture permeability of the moisture-proof layer 7 is 200 g/m ² /24 hrs or less, and preferably 150 g/m ² /24 hrs or less from the viewpoint of heat resistance and moisture resistance of the obtained polarizing plate. Further, the phase difference of the moisture-proof layer 7 is preferably 100 nm or more from the viewpoint of visibility when the polarized sunglasses are provided.

The method of forming the moisture-proof layer 7 is, for example, the surface of the polarizing layer 5 on the opposite side to the base film 1 and coated in the predetermined slow axis direction. a method of forming a phase difference between a liquid crystal material having a moisture permeability and a phase difference; (2) a surface of the polarizing sublayer 5 opposite to the base film 1 and having a moisture permeability of 200 g/m ² It is preferable to use the retardation film having a phase difference of 100 nm or less in the in-plane phase of 24 hrs or less, and the retardation axis is set to an angle θ of 20 degrees or more and 70 degrees or less with respect to the absorption axis of the polarizer layer 5, and the like. (2) method.

The retardation film is usually a film which imparts the phase difference by the stretching treatment. The phase of the retardation axis of the retardation film is derived from the phase The material of the difference film and the direction of extension are determined. For example, in the case of longitudinal uniaxial stretching or lateral uniaxial stretching, a slow phase axis is provided in parallel or perpendicular to the longitudinal direction of the film depending on the material of the film. When such a retardation film is used, after the film is cut, the slow axis is bonded to the absorption axis of the polarizer layer in a direction of 20 degrees or more and 70 degrees or less. In addition, when a film which is uniaxially stretched in the oblique direction so that the retardation axis in the longitudinal direction of the film is 20 degrees or more and 70 degrees or less is used as the retardation film, the retardation film can be a so-called roll to a roll ( The roll-to-roll method is bonded to a polarizing laminated film having an absorption axis parallel to the longitudinal direction. From the viewpoint of production efficiency, it is preferable to be the latter case. The means for achieving the oblique optical axis is not particularly limited, and may be obliquely extended or laterally extended. When the lateral direction is extended, the optical axis outside the central portion is inclined by intentionally increasing the shape of the Boeing in the width direction. Therefore, this portion is suitably used as a retardation film.

The material forming the moisture-proof layer may be selected from resins having a moisture permeability of 200 g/m ² /24 hrs or less, such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate. A polyester resin film, a cyclic polyolefin resin film, a polycarbonate resin film, a (meth)acrylic resin film, a polypropylene resin film, or the like.

The polyester resin is a polymer having an ester bond, and is mainly a polycondensate of a polyvalent carboxylic acid and a polyhydric alcohol. The polycarboxylic acid to be used mainly uses a divalent dicarboxylic acid such as isophthalic acid, terephthalic acid, dimethyl terephthalate or dimethyl naphthalate. Further, the polyol to be used mainly uses a divalent diol, and examples thereof include propylene glycol, butylene glycol, and neopentyl glycol. Cyclohexanedimethanol and the like.

Specific examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, and polytrimethylene terephthalate. Diester, propylene naphthalate, dimethyl dimethyl terephthalate, cyclohexane dimethyl phthalate, and the like. These mixed resins and copolymers can be suitably used.

For the cyclic polyolefin resin, various suitable commercial products can be used, for example, Topas (registered trademark) (manufactured by Ticona Co., Ltd.), Arton (registered trademark) (manufactured by JSR Co., Ltd.), and ZEONOR (registered trademark) (Japan Zeon Co., Ltd.) Manufactured by the company, ZEONEX (registered trademark) (made by Japan Zeon Co., Ltd.), APL (registered trademark) (made by Mitsui Chemicals Co., Ltd.), etc. When a film made of such a cyclic polyolefin resin is used as a film, a conventional method such as a solvent casting method or a melt extrusion method can be suitably used. In addition, it is possible to use a pre-formed ring such as Escena (registered trademark) (made by Sekisui Chemical Co., Ltd.), SCA40 (made by Sekisui Chemical Co., Ltd.), ZEONOR (registered trademark) film (made by Optec Co., Ltd., Japan) A commercially available product of a film made of a polyolefin resin.

The cyclic polyolefin-based resin film may be uniaxially stretched or biaxially stretched. Any phase difference value which can be imparted to the cyclic polyolefin-based resin film can be imparted by stretching. The stretching is generally performed continuously while winding up the film roll, and the heating furnace 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-based resin film to the glass transition temperature + 100 °C. Extension ratio, usually 1.1 to 6 times in one direction, which is reasonable I want to be 1.1 to 3.5 times.

Since the cycloolefin-based resin film generally has poor surface activity, it is preferred to subject the surface to be bonded to the polarizing laminate film to a surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame treatment, or saponification treatment. Among them, plasma treatment and corona treatment which are easier to implement are suitable.

The thickness of the moisture-proof layer is preferably 90 μm or less from the viewpoint of reducing the thickness of the obtained polarizing plate, and more preferably 50 μm or less. On the other hand, it is preferable that it is 5 μm or more from the viewpoint of the mechanical strength of the process of obtaining the polarizing plate and the like.

The retardation film may be subjected to a surface treatment in advance on a surface opposite to the bonding surface of the polarizing sublayer. The surface treatment may, for example, be a treatment for forming a hard coat layer, an antistatic layer, an antifouling layer, an antireflection layer, or an antiglare layer. It is also possible to combine the surface treatments of the plural. The method of forming the surface treatment layer on the surface of the retardation film is not particularly limited, and a conventional method can be used.

(hard coating)

The hard coat layer has a function of increasing the surface hardness of the film, and is provided for the purpose of preventing surface scratches and the like. The hard coat layer exhibits H or is harder than the hard value in the pencil hardness test prescribed in JIS K 5600-5-4. In the case of forming the hard coat layer, there is an advantage that it is not easily injured when the manufacturing step or the final product is wiped with a cloth or the like, for example, to remove surface contamination. The material forming such a hard coat layer is generally hardened by heat or light. For example, an organic polyoxyl resin system, a melamine system, an epoxy system, an acrylic system, An organic hard coat material such as a urethane acrylate or an inorganic hard coat material such as cerium oxide.

(antistatic layer)

The antistatic layer imparts conductivity to the surface of the film and is provided for the purpose of suppressing the influence of static electricity. For the formation of the antistatic layer, for example, a method of applying a resin composition containing a conductive substance (antistatic agent) can be employed. For example, an antistatic agent is coexisted in the hard coat material used for the formation of the above hard coat layer, whereby an antistatic hard coat layer can be formed.

(anti-fouling layer)

The antifouling layer is provided to impart water repellency, oil repellency, stain resistance, and the like to the surface of the film. A suitable material for forming the antifouling layer is a fluorine-containing organic compound. Examples of the fluorine-containing organic compound include carbon fluoride, perfluorodecane, and the like. The method for forming the antifouling layer varies depending on the material to be formed, and a physical vapor deposition method, a chemical vapor deposition method, a wet coating method, or the like which is a representative example of vapor deposition or sputtering can be used. The average thickness of the antifouling layer is usually from 1 to 50 nm, more preferably from 3 to 35 nm.

(anti-reflection layer)

The antireflection layer is a layer for preventing external light reflection on the incident film, and is provided on the outermost layer of the film (the surface exposed to the outside). In this case, it may be formed directly on the film, or may be formed on the outermost surface of other layers such as a hard coat layer. The film provided with the antireflection layer is preferably a reflectance of 5% or less at an incident angle of 5 to 700 nm for light having a wavelength of 430 to 700 nm, and particularly preferably a reflectance of 1% or less at the same incident angle for light having a wavelength of 550 nm.

The thickness of the antireflection layer may be from 0.01 to 1 μm , and more preferably in the range of from 0.02 to 0.5 μm . The antireflection layer may be composed of a low refractive index layer having a refractive index smaller than that of the layer provided with the antireflection layer, specifically, a refractive index of 1.30 to 1.45; a low refractive index layer of a film composed of an inorganic compound, The high refractive index layer of the film composed of the inorganic compound is alternately laminated with a plurality of layers or the like.

The material forming the low refractive index layer is not particularly limited as long as it has a low refractive index. For example, a resin material such as an ultraviolet curable acrylic resin, a hybrid material in which an inorganic fine particle such as a cerium sol is dispersed in a resin, a sol-gel material containing an alkoxy decane, or the like can be given. Such a low refractive index layer can be formed by coating a polymer obtained by polymerization, or can be applied in the state of a monomer or an oligomer of a precursor and then formed by polymerization hardening. Further, in order to impart stain resistance, each material preferably includes a compound having a fluorine atom in the molecule.

(anti-glare layer)

The anti-glare layer is formed by dispersing reflection of external light on the film into various angles, and is provided to reduce specular reflection such as a fluorescent lamp or sunlight. Thereby, the image such as a fluorescent lamp is less likely to be reflected, and the visibility of the display device is improved. The anti-glare layer may be a method of dispersing fine particles in a photocurable resin or a method of forming fine concavo-convex shapes on the surface by embossing.

When the fine particles as described above are used for the formation of the antiglare layer, the inorganic or organic fine particles are dispersed in the respective components constituting the photocurable resin composition, and then the resin composition is applied onto the film to form a transparent film by irradiation with light. A hard coat layer (anti-glare layer) in which fine particles are dispersed in the resin.

On the other hand, it is formed by embossing with a fine form In the case of the anti-glare layer having a concave-convex shape, a shape in which a fine uneven shape is formed can be used to transfer the shape of the mold to the resin layer formed on the film. When the fine surface uneven shape is formed by the embossing method, the resin layer transferred by the uneven shape may contain inorganic or organic fine particles or may not be contained. The transfer of the uneven shape by the embossing method is preferably a UV embossing method using an ultraviolet curable resin.

In the moisture-proof layer forming step, the moisture-proof layer 7 can be formed by penetrating the adhesive layer on the surface of the polarizing layer 5 opposite to the base film 1 . Here, the adhesive layer may be a water-based adhesive layer or a photo-curable adhesive layer, and may be controlled from the point that the moisture-proof layer may be followed by a small amount of moisture, and the solution may be curled by the solution, or may not be dried. From this point of view, it is more preferable to form the moisture-proof layer 7 via the photo-curable adhesive layer.

The aqueous binder is, for example, a polyvinyl alcohol resin aqueous solution or an aqueous two-liquid urethane latex adhesive. Among them, a polyvinyl alcohol-based resin aqueous solution is suitably used. In the polyvinyl alcohol-based resin used as an adhesive, in addition to the vinyl alcohol homopolymer obtained by subjecting the polyvinyl acetate of the homopolymer of vinyl acetate to saponification, vinyl acetate may be copolymerized therewith. A vinyl alcohol-based copolymer obtained by subjecting a copolymer of another monomer to a saponification treatment, and a modified polyvinyl alcohol-based polymer modified with the hydroxyl group. A polyvalent aldehyde, a water-soluble epoxy compound, a melamine-based compound, a zirconia compound, a zinc compound or the like as an additive may be added to the aqueous binder. When such a water-based adhesive is used, the adhesive layer obtained therefrom is usually much thinner than 1 μm , and the adhesive layer is practically invisible even when observed in a usual optical microscope.

The bonding method of the film using the water-based adhesive is not particularly limited, and for example, a method of uniformly applying or flowing an adhesive on the surface of the film, laminating another film on the coated surface, and bonding and drying by a roller 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.

When a water-based adhesive is used, after the film is bonded, the water contained in the water-based adhesive is removed and dried. The temperature of the drying oven is preferably from 30 ° C to 90 ° C. When it is less than 30 ° C, there is a tendency that the adhesive surface is easily peeled off. At 90 ° C or higher, the optical performance is deteriorated due to heat. The drying time can be from 10 to 1000 seconds.

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

The photocurable adhesive refers to an adhesive which is cured by irradiation with an active energy ray such as ultraviolet rays, for example, a polymerizable compound and a photopolymerization initiator, a photoreactive resin, a binder resin, and a photoreactive crosslink. Agents, etc. The polymerizable compound may be a photopolymerizable monomer such as a photocurable epoxy monomer, a photocurable acrylic monomer, or a photocurable urethane monomer, or an oligomer derived from the monomers. Things and so on. The photopolymerization initiator may be one containing an active species that emits an active energy ray such as ultraviolet rays to generate a neutral radical, an anionic radical, or a cationic radical. The photocurable adhesive containing a polymerizable compound and a photopolymerization initiator is preferably a photocurable epoxy monomer and a photocationic polymerization initiator.

The method of bonding the film with a photocurable adhesive can be carried out by a conventionally known method, for example, by a flow casting method, a Mayer bar method, a gravure coating method, a notch wheel coating method, or a doctor blade coating method. A method of applying an adhesive to the adhesive surface of the film and laminating two films by a cloth method, a die coating method, a dip coating method, a spray method, or the like. The casting method refers to a method in which two films of a material to be coated are moved in a direction perpendicular to the vertical direction, about the horizontal direction, or both, and an adhesive is applied to the surface thereof and diffused.

After applying the adhesive to the surface of the film, the bonding film is pinched by a pinch roller to thereby follow. Further, a method of pressurizing and uniformly rolling the laminated body with a roller or the like can be suitably used. In this case, the material of the roller can be metal, rubber or the like. Further, it is preferable to use a method in which the laminated body is pressed and pressed between the roller and the roller. In this case, the rollers may be of the same material or different materials. The thickness of the adhesive layer after bonding using the above-described gripping roller is preferably 5 μm or less and 0.01 μm or more.

On the adhesion surface of the film, surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame treatment, or saponification treatment can be appropriately performed in order to improve the adhesion. The saponification treatment may be a method of immersing in an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide.

When a photocurable resin is used as an adhesive, the photocurable adhesive is cured by irradiating an active energy ray after the film is laminated. The light source of the active energy ray is not particularly limited, and is preferably an active energy ray having a light-emitting distribution with a wavelength of 400 nm or less. Specifically, it is preferably a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high pressure mercury lamp, and a chemistry. Lamps, black lights, microwave excited mercury lamps, metal halide lamps, etc.

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, it is preferable that the irradiation intensity in the wavelength region effective for activating the polymerization initiator is 0.1 to 6000 mW/cm. ² . When the irradiation intensity is 0.1 mW/cm ² or more, the reaction time does not become too long, and when it is 6000 mW/cm ² or less, the epoxy resin is caused by heat radiated from the light source and heat generated by curing of the photocurable adhesive. The yellowing and the deterioration of the polarizing film are less likely to occur. The light irradiation time of the photocurable adhesive is applied depending on the cured photocurable adhesive, and is not particularly limited. However, it is preferable to set the cumulative light amount which is a product of the irradiation intensity and the irradiation time to 10 to 10000 mJ. /cm ² . When the cumulative light amount of the photocurable adhesive is 10 mJ/cm ² or more, the active species derived from the polymerization initiator are sufficiently generated, and the hardening reaction can be more reliably performed, and the reaction time is not satisfied at 10000 mJ/cm ² or less. It will become too long to maintain good productivity. Further, the thickness of the adhesive layer after the irradiation of the active energy ray is usually 0.001 to 5 μm , preferably 0.01 μm or more and 2 μm or less, more preferably 0.01 μm or more and 1 μm or less.

When the photocurable adhesive of the film including the polarizing layer and the moisture-proof layer is cured by irradiation of the active energy ray, it is preferable not to reduce the polarization degree, transmittance, color tone, and moisture resistance of the polarizing sub-layer. The transparency of the layer is performed under the conditions of each function of the polarizing plate.

[Peeling step (S50)]

In the peeling step, the base film 1 is peeled off from the multilayer film 8 to obtain a polarizing plate 9 (Fig. 1 (E)). Substrate film 1 The peeling method is not particularly limited, and it may be directly peeled off, or may be rolled into a roll shape and then provided with a peeling step and peeled off.

<Polarizing plate, polarizing plate with adhesive layer>

The polarizing plate 9 can be obtained by the above steps S10 to S50. Here, the polarizing plate 9 obtained by the manufacturing method of the present invention will be described with reference to Figs. 3 to 6 . The polarizing plate 9 of the present invention has a moisture-proof layer 7 and a polarizing sub-layer 5 as shown in Fig. 3 . Further, as shown in Fig. 4, it is preferable that the adhesive layer 10 is present between the moisture-proof layer 7 and the polarizer layer 5. Further, as shown in Fig. 5, the adhesive layer 11 is provided on the surface of the polarizing sub-layer 5 opposite to the moisture-proof layer 7, and the polarizing plate 20 with the adhesive layer can be provided. The polarizing plate 20 with the adhesive layer is attached to the image display unit 12 on the side of the adhesive layer 11, and can be the image display device 30.

The visibility correction single transmittance (Ty) of the polarizing plate 9 is 40% or more, and the visual sensitivity correction polarization (Py) is 99.9% or more. The polarizing plate 9 can be used as a polarizing plate of an image display device. The polarizing plate 9 has the above-described optical characteristics, whereby a good contrast display can be obtained when the polarizing plate 9 uses a polarizing plate as an image display device.

The adhesive used for the polarizing plate 20 to which the adhesive layer is applied may be an acrylic resin, a styrene resin, a polyoxymethylene resin, or the like, and a matrix polymer is added to the matrix polymer, and an isocyanate compound or epoxy is added to the matrix polymer. A composition of a crosslinking agent such as a compound or aziridine or the like. The matrix polymer contains fine particles, and can be an adhesive layer exhibiting light scattering properties.

The thickness of the adhesive layer 11 is preferably from 1 to 40 μm , and is preferably applied in a thin range of characteristics of non-destructive workability and durability, and more preferably from 3 to 25 μm . It is good in workability at 3 to 25 μm and suppresses dimensional change of the polarizing film to a suitable thickness. When the adhesive layer 11 is less than 1 μm , the adhesiveness is lowered, and when it exceeds 40 μm , the adhesive is likely to be oozing out.

The method of forming the adhesive layer 11 on the polarizer layer 5 is not particularly limited, and a solution containing the components represented by the above-mentioned matrix polymer may be applied onto the polarizer layer 5 to be dried and formed into the adhesive layer 11. Further, it may be bonded to a separator or another film, or may be formed by laminating a surface of the polarizing layer after forming an adhesive layer on the separator. Further, when the adhesive layer is formed on the surface of the polarizer layer, it may be subjected to a close treatment on the surface of the polarizer layer or one side or both sides of the adhesive layer as needed, for example, corona treatment or the like.

The image display unit 12 is, for example, a liquid crystal panel including a liquid crystal cell between glass substrates, an organic EL element, or the like. The liquid crystal cell can use various conventional driving methods.

Further, in the polarizing plate 9, other optical layers may be provided on the surface of the moisture-proof layer 7 opposite to the polarizing sub-layer 5 as needed. Here, the other optical layer includes, for example, a reflective polarizing film that transmits light of a certain polarized light and reflects light having a polarized light of opposite nature, a film having an anti-glare function having a concave-convex shape on the surface, and a surface anti-reflection. A film with a reflective function, a reflective film with a reflective function on the surface, a transflective film with both a reflective function and a penetrating function, and a viewing angle compensation film.

A commercially available product of a reflective polarizing film that transmits light of a certain polarized light and reflects light having a polarizing property opposite thereto, for example, DBEF (made by 3M company, available from Sumitomo 3M Co., Ltd.), APF (made by 3M company, available from Sumitomo 3M Co., Ltd.), etc. For the viewing angle compensation film, for example, an optical compensation film in which a liquid crystal compound is applied to the surface of the substrate, a retardation film made of a polycarbonate resin, and a retardation film made of a cyclic polyolefin resin are used. A commercially available product of an optical compensation film which is coated with a liquid crystal compound and which is aligned on the surface of the substrate, and a WV film (manufactured by Fuji Film Co., Ltd.) and an NH film (manufactured by Nippon Oil Co., Ltd.), NR film (manufactured by Nippon Oil Co., Ltd.) and the like. In addition, the commercial product of the retardation film which consists of a cyclic polyolefin resin is an Arton (trademark) film (made by JSR Corporation), and Escena (registered trademark) (The Sekisui Chemical Industry Co., Ltd. Company system), ZEONOR (registered trademark) film (made by Optes Co., Ltd.), etc.

<Method of Manufacturing Circular Polarizing Plate>

The method for producing a circularly polarizing plate of the present invention includes a resin layer forming step (S10) of forming a polyvinyl alcohol-based resin layer on at least one surface of a base film to obtain a laminated film; and uniaxially stretching the laminated film to polyvinyl alcohol a thickness of the resin layer is 10 μm or less to obtain an extending step of the stretched film (S20); dyeing the stretched film with a dichroic dye and forming a polarizing layer to obtain a dyeing step of the polarizing laminated film (S30); In the polarizing layered film, a moisture-proof layer is formed by transmitting a light-resistant adhesive layer on a surface of the polarizer layer opposite to the base film, thereby obtaining a moisture-proof layer forming step of the multilayer film (S40). a peeling step (S50) of peeling off the base film from the multilayer film to obtain a polarizing film with a moisture-proof layer; and a moisture-proof film with a moisture-proof layer, and the aforementioned moisture-proof layer The surface on the opposite side of the layer forms a phase difference layer forming step of the phase difference layer (S60). The resin layer forming step (S10), the stretching step (S20), the dyeing step (S30), the moisture-proof layer forming step (S40), and the peeling step (S50) are the same as the method of manufacturing the polarizing plate described above, and therefore the phase will be described in detail below. The difference layer forming step (S60). Further, the polarizing plate 9 obtained in the peeling step of the above-described method for producing a polarizing plate can be regarded as a polarizing film having a moisture-proof layer obtained in the peeling step of the method for producing a circular polarizing plate.

[Phase difference layer forming step (S60)]

In the retardation layer forming step, in the polarizing film 9 with the moisture-proof layer, the phase difference layer 13 is formed on the surface of the polarizing sub-layer 5 opposite to the moisture-proof layer 7 (Fig. 7). Here, it is preferable that the phase difference layer 13 is formed to pass through the adhesive layer 11. Further, when the second retardation layer 13b (Fig. 8) is formed in addition to the retardation layer 13, it is preferable to laminate the interlayer by the adhesive layer 11b.

(phase difference layer 13)

The phase difference layer 13 is a layer that functions to prevent external light from being reflected by causing light that is incident on the image display device from outside to be circularly polarized, thereby preventing light from being emitted to the outside. Therefore, normally, the phase difference layer 13 is disposed inside the image display device. The phase difference layer 13 can be appropriately selected from a 1⁄2 wavelength plate, a 1⁄4 wavelength plate, a 1/5 wavelength plate, a 1/6 wavelength plate, etc., depending on the use of the circularly polarizing plate having the layer or the like. For example, when the one-layer retardation layer 13 is provided as shown in Fig. 7, it is preferable to use a quarter-wavelength plate as the retardation layer 13. Alternatively, as shown in FIG. 8, the second phase difference layer is further provided in addition to the phase difference layer 13. In the case of 13b, it is preferable to use the 1/2 wavelength plate as the retardation layer 13 and the 1/4 wavelength plate as the second retardation layer 13b. The configuration having the two-layered retardation layer in Fig. 8 is preferable because it is possible to produce circularly polarized light in a wide-wavelength region of visible light.

The retardation layer is, for example, a retardation film made of a triacetyl cellulose resin, a polycarbonate resin, or a cyclic polyolefin resin. For example, Arton (registered trademark) (manufactured by JSR Co., Ltd.) and Escena (registered trademark) (manufactured by Sekisui Chemical Co., Ltd.) are available as a commercial product of a retardation film composed of a cyclic polyolefin resin. ZEONOR (registered trademark) film (manufactured by Optecs Co., Ltd., Japan).

The retardation layer 13 can be laminated via the adhesive layer 11 as shown in Figs. 7 and 8. Further, in the case of having two retardation layers, these may be sequentially laminated through the adhesive layers (11, 11b). As the adhesive constituting the pressure-sensitive adhesive layer, a conventionally known adhesive can be used, and examples thereof include an acrylic pressure-sensitive adhesive, an urethane-based pressure-sensitive adhesive, and a polyoxymethylene resin-based pressure-sensitive adhesive. Among them, from the viewpoints of transparency, adhesion, reliability, rework, and the like, it is preferred to use an acrylic adhesive. The adhesive layer can be provided by applying the above-mentioned adhesive to the surface of the film by a die coater, a gravure coater or the like and drying it. Alternatively, an adhesive layer may be provided by transferring a sheet-like adhesive formed on a release-treated plastic film (referred to as a release film) onto the surface of the film. The thickness of the adhesive layer is not particularly limited, and is preferably in the range of 2 to 40 μm .

<Circular polarizing plate, circular polarizing plate with adhesive layer, image display device>

In a video display device such as a liquid crystal display device or an organic EL display device, a circularly polarizing plate is provided on the viewing side thereof in order to prevent reflection of external light. Such a circularly polarizing plate has a retardation layer such as a polarizing sub-layer and a quarter-wavelength plate, and light incident on the image display device from outside is circularly polarized, thereby preventing light from being emitted to the outside, and as a result, external light can be prevented. Since the reflection is performed, the phase difference layer is usually disposed inside the image display device.

The circular polarizing plate 20 can be obtained by the above steps S10 to S60. Further, as shown in Fig. 9, an adhesive layer 11b is provided on the surface of the phase difference layer 13 opposite to the polarizing sub-layer 5, and the circular polarizing plate 50 to which the adhesive layer is attached can be obtained. Alternatively, as shown in Fig. 10, when the second retardation layer 13b is provided, the adhesive layer 11c is provided on the surface of the phase difference layer 13b opposite to the polarizing sub-layer 5, and circular polarized light with an adhesive layer can be provided. Board 50. The circular polarizing plate 50 with the adhesive layer is attached to the image display unit 12 on the side of the adhesive layers 11b and 11c as shown in Figs. 11 and 12, and can be the image display device 30.

Further, in the circular polarizing plate 40, other optical layers may be provided on the surface of the moisture-proof layer 7 opposite to the polarizing sub-layer 5 as needed. Here, as the other optical layer system, as in the case of the polarizing plate 9, for example, a reflective polarizing film that transmits light of a certain polarized light and reflects light having a polarized light of opposite nature, and an anti-glare function having a concave-convex shape on the surface The film, the film with a surface anti-reflection function, a reflective film having a reflective function on the surface, a semi-transmissive reflective film having both a reflection function and a penetrating function, and a viewing angle compensation film.

(Example)

The present invention will be more specifically described below by way of examples and comparative examples, but the invention is not limited to the examples.

[Example 1] (substrate film)

The base film was an unstretched polypropylene (PP) film (melting point: 163 ° C) having a thickness of 110 μm .

(formation of undercoat layer)

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

(Polyvinyl alcohol-based resin layer forming step)

Polyvinyl alcohol powder (manufactured by Kuraray Co., Ltd., average polymerization degree 2400, saponification degree: 98.0 to 99.0 mol%, trade name: PVA124) was dissolved in hot water at 95 ° C to prepare a polyvinyl alcohol aqueous solution having a concentration of 8 wt%. . The obtained aqueous solution was applied onto the undercoat layer by a lip coater, and dried at 80 ° C for 20 minutes to prepare a three-layer laminated film comprising a base film, an undercoat layer, and a polyvinyl alcohol-based resin layer.

(extension step)

The above laminated film was stretched at 160 ° C using a tenter device A 5.8-fold free end uniaxial extension was applied to obtain an extended film. The thickness of the stretched polyvinyl alcohol-based resin layer was 5.0 μm.

(staining step)

The stretched film was immersed in a dyeing solution of a mixed aqueous solution of iodine and potassium iodide at 26 ° C for 90 seconds, and 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 300 seconds. It was then washed with pure water at 10 ° C for 10 seconds and finally dried at 80 ° C for 200 seconds. The polarizing layer was formed from the resin layer by the above steps, and a polarizing laminated film was obtained. The compounding ratio of each solution is, for example, the following.

<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

(moisture-proof layer forming step)

In the polarizing layered film, a photocurable adhesive (ADEKA OPTOMER KR-25T) is applied to the surface of the polarizer layer opposite to the base film, and then bonded to the coated surface as a moisture-proof layer. Ethylene phthalate film (transparent humidity: 33 g/m ² /24 hrs, thickness: 25 μm), such that the slow axis forms an angle of 45 degrees with respect to the absorption axis of the aforementioned polarizing layer, and the moisture-proof layer is obtained. A multilayer film composed of five layers of an adhesive layer, a polarizer layer, an undercoat layer, and a base film. The base film was peeled off from the obtained multilayer film to obtain a polarizing plate composed of four layers of a moisture-proof layer, an adhesive layer, a polarizing layer, and an undercoat layer.

[Embodiment 2]

A polarizing plate was obtained in the same manner as in Example 1 except that a polyethylene terephthalate film (water permeability: 140 g/m ² /24 hrs, thickness: 5 μm) was used for the moisture-proof layer.

[Example 3]

A polarizing plate was obtained in the same manner as in Example 1 except that a film composed of a cycloolefin polymer (water permeability: 110 g/m ² /24 hrs, thickness: 20 μm) was used in the moisture-proof layer.

[Comparative Example 1]

A polarizing plate was obtained in the same manner as in Example 1 except that a triacetyl cellulose film (water permeability: 827 g/m ² /24 hrs, thickness: 42 μm) was used for the moisture-proof layer.

[Comparative Example 2]

The same procedure as in Example 1 was carried out except that the moisture-proof layer was a film of a triacetyl cellulose film (water permeability: 827 g/m ² /24 hrs, thickness: 42 μm) and a water-based adhesive was used as the adhesive. Polarizer. In the water-based adhesive, polyvinyl alcohol powder ("KL-318" manufactured by Kuraray Co., Ltd., average polymerization degree 1800) was dissolved in hot water at 95 ° C to prepare a polyvinyl alcohol aqueous solution having a concentration of 3 wt%. To the obtained aqueous solution, 1 part by weight of a crosslinking agent ("SUMIREZ RESIN 650" manufactured by Sumitomo Chemical Co., Ltd.) in an amount of 2 parts by weight of the polyvinyl alcohol powder was mixed to obtain an adhesive solution.

(Measurement of polarized light performance)

The optical characteristics of the polarizing plates obtained in Examples 1 to 3 and Comparative Examples 1 to 2 were measured by a spectrophotometer (manufactured by JASCO Corporation, V7100) equipped with an integrating sphere. The MD transmittance and the TD transmittance were determined in the range of 380 nm to 780 nm, and the monomer transmittance and the polarization degree of each wavelength were calculated according to the following formulas (1) and (2), and then JIS Z was used. The 2701 field of view (C light source) of 8701 performs visual sensitivity correction, and obtains the visual sensitivity correction unit transmittance (Ty) and the visual sensitivity correction polarization (Py). Further, the measurement of the polarizing plate is performed such that the moisture-proof layer side is the detector side and light is incident from the undercoat layer side.

In the above, "MD penetration rate" refers to the transmittance when the direction of the polarized light from Glan-Thompson is parallel to the transmission axis of the polarizing plate sample, and the formula (1), (2) is indicated by "MD". Further, "TD penetration rate" refers to the transmittance when the direction of the polarization from Grand-Thompson is perpendicular to the transmission axis of the polarizing plate sample, and "TD" in the equations (1) and (2). Said.

Monomer penetration rate (%) = (MD + TD) / 2.. Formula (1)

Polarization degree (%) = {(MD-TD) / (MD + TD)} × 100.. Equation (2)

(heat resistance, moisture resistance test)

The polarizing plates obtained in Examples 1 to 3 and Comparative Examples 1 to 2 were placed in an environment of 60 ° C and 90% RH for 750 hours, and then Py, Ty of the polarizing plate. The evaluation results are shown in Table 1. In addition, Ty (%) at the beginning of Table 1 and Py (%) at the beginning of the test refer to Ty (%) and Py (%) at the start of the test, and Py (%) at the end refers to the end of the test. Py (%) and ΔPy (%) refer to the difference between Py (%) at the end and the Py (%) at the start.

[Example 4]

The polyethylene terephthalate is used every 10 degrees so that the retardation axis of the polyethylene terephthalate film of the moisture barrier layer is from 0 to 90 degrees to the absorption axis of the polarizing layer. The film was attached to a polarizing laminated film, and the obtained polarizing plates were evaluated for visibility when wearing sunglasses. Vision The person with good literacy is "○", and the person with poor visibility is "X". The results are shown in Table 2.

1‧‧‧Substrate film

2‧‧‧Polyvinyl alcohol resin layer

3‧‧‧ laminated film

4‧‧‧Extended film

5‧‧‧ polarized sublayer

6‧‧‧Polarized laminated film

7‧‧‧Wetproof layer

8‧‧‧Multilayer film

9‧‧‧Polar plate

Claims (10)

A method for producing a polarizing plate, comprising: a resin layer forming step of forming a polyvinyl alcohol-based resin layer on at least one side of a base film to obtain a laminated film; and an extending step of uniaxially stretching the laminated film to polyethylene The thickness of the alcohol-based resin layer is 10 μm or less to obtain a stretched film; the dyeing step is to form the polarizing layer by dyeing the stretched film with a dichroic dye to obtain a polarizing layer; and a moisture-proof layer forming step; In the polarizing laminate film, an in-plane retardation having a moisture permeability of 200 g/m ² /24 hrs or less is formed on a surface of the polarizing layer opposite to the base film, and the retardation axis is 100 nm or more. The moisture barrier layer having an angle θ with respect to the absorption axis of the polarizer layer is 20 degrees or more and 70 degrees or less, and a multi-layer film; and a peeling step of peeling off the base film from the multilayer film. The method for producing a polarizing plate according to claim 1, wherein in the moisture-proof layer forming step, a photocurable adhesive layer is interposed on a surface of the polarizer layer opposite to the base film. A moisture barrier is formed. The method for producing a polarizing plate according to the first or second aspect of the invention, wherein in the moisture-proof layer forming step, a moisture permeability of 200 is applied to a surface of the polarizing sub-layer opposite to the substrate film. A retardation film having a phase difference of 100 nm or more in g/m ² /24 hrs or less is an angle θ of 20 degrees or more and 70 degrees or less with respect to the absorption axis of the retardation layer. The method for producing a polarizing plate according to any one of the first to third aspect, wherein the retardation film is subjected to a surface treatment on a surface opposite to a bonding surface of the polarizing sublayer. A polarizing plate with an adhesive layer, comprising: a polarizing plate manufactured by the method according to any one of claims 1 to 4; and an anti-reflection layer disposed on the polarizing layer of the polarizing plate Adhesive layer on the opposite side of the wet layer. An image display device comprising: a polarizing plate with an adhesive layer as described in claim 5; and an image display unit attached to an adhesive layer side of the polarizing plate. A circularly polarizing plate comprising: a polarizing plate with an adhesive layer as described in claim 5; and a retardation layer attached to an adhesive layer side of the polarizing plate. A circularly polarizing plate with an adhesive layer, comprising: a circular polarizing plate according to claim 7 of the patent application; and a surface of the polarizing sub-layer disposed on the circular polarizing plate opposite to the moisture-proof layer Agent layer. An image display device comprising: a circularly polarizing plate with an adhesive layer as described in claim 8; and an image display unit attached to an adhesive layer side of the circular polarizing plate. A method for producing a circularly polarizing plate, comprising: a resin layer forming step of forming a polyvinyl alcohol-based resin layer on at least one side of a base film to obtain a laminated film; and an extending step of uniaxially stretching the laminated film to a poly The thickness of the vinyl alcohol-based resin layer is 10 μm or less to obtain a stretched film; the dyeing step is to form the polarizing layer by dyeing the stretched film with a dichroic dye to obtain a polarizing layer; the moisture-proof layer forming step In the polarizing laminate film, a surface having a moisture permeability of 200 g/m ² /24 hrs or less is formed on the surface of the polarizer layer opposite to the base film via the photocurable adhesive layer. a moisture barrier layer having a phase difference of 100 nm or more and an angle θ of the retardation axis with respect to an absorption axis of the polarizing sublayer of 20 degrees or more and 70 degrees or less to obtain a multilayer film; and a peeling step of peeling off the substrate from the multilayer film a thin film to obtain a polarizing film with a moisture-proof layer; and a retardation layer forming step of the polarizing film with the moisture-proof layer attached thereto, on the opposite side of the polarizing layer from the moisture-proof layer Forming a retardation layer.