KR101711265B1 - Polarizing laminate film, polarizing plate, and method for producing each - Google Patents

Abstract

A thin polarizing plate capable of providing a good contrast ratio in a liquid crystal display device having a protective film and a polarizer layer formed on one side of a protective film, wherein the polarizer layer has a thickness of 10 mu m or less , A saponification degree of the polyvinyl alcohol resin is 99.0 mol% or less, a visual sensitivity-corrected single-use transmittance (Ty) of 40% or more, and a visual sensitivity correction polarity Py) is 99.9% or more.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a polarizing laminated film, a polarizing plate,

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

BACKGROUND ART A polarizing plate is widely used as a polarizing light supply element in a display device such as a liquid crystal display device. As such a polarizing plate, a polarizing film made of a polyvinyl alcohol-based resin has been conventionally adhered to a protective film made of triacetyl cellulose. Recently, liquid crystal displays have become thinner and lighter .

As a method for producing such a thin polarizing plate, a polarizing laminated film having a polarizing layer is obtained by forming a polyvinyl alcohol-based resin layer on the surface of a base film, followed by stretching and dyeing, , A method in which a protective film is bonded to the polarizing laminated film and then a base film is peeled off is used as a polarizing plate (for example, JP 2000-338329-A, JP 2009-93074-A, JP2009-98653-A And JP2003-43257-A).

In the polarizing plate obtained by forming the polyvinyl alcohol resin layer on the surface of the base film obtained by the above-described conventional method, the resin layer is formed by directly coating an aqueous solution of the polyvinyl alcohol resin on the surface of the base film, There is an advantage that a polyvinyl alcohol layer which is significantly thinner than that in the case of using a film master of a vinyl-based resin can be obtained.

However, when the polarizing plate obtained by the above-described conventional method is used for a liquid crystal display device, the contrast of the liquid crystal display device may not necessarily be sufficient.

Therefore, an object of the present invention is to provide a thin polarizing plate capable of providing a good contrast ratio in a liquid crystal display, a polarizing laminated film used therefor, and a method for producing the same.

As a result of intensive studies of the present inventors, it has been found that when the resin layer is formed using a general-purpose polyvinyl alcohol resin having a saponification degree exceeding 99.0 mol% in the above-mentioned conventional method, the polarizing performance of the resulting polarizing plate is sufficient As a result, it has been found that the contrast ratio of a liquid crystal display using a polarizing plate is not necessarily sufficient, and the present invention has been completed.

The present invention includes the following.

[1] A polarizing plate comprising a base film and a polarizer layer formed on one side of the base film, wherein the polarizer layer is formed of a polyvinyl alcohol resin having a thickness of 10 탆 or less and a dichroic dye adsorbed and oriented, Wherein the degree of saponification of the alcohol-based resin is not more than 99.0 mol%, the visibility-corrected single transmittance (Ty) is not less than 40%, and the visual sensitivity correction polarity (Py) is not less than 99.9%.

[2] The polarizing laminated film according to [1], wherein the polarizer layer is uniaxially stretched at a draw ratio exceeding 5 times.

[3] The polarizing laminated film according to [1] or [2], which is used for a polarizing plate.

[4] The polarizing laminated film described in any one of [1] to [3], wherein the polarizer layer is formed on one side of the base film via a primer layer.

[5] A polarizing plate comprising a protective film and a polarizer layer formed on one side of the protective film, wherein the polarizer layer is formed of a polyvinyl alcohol resin having a thickness of 10 μm or less and a dichroic dye adsorbed and oriented, Wherein the degree of saponification of the alcohol-based resin is 99.0 mol% or less, the visual sensitivity-corrected single transmission (Ty) is 40% or more, and the visual sensitivity correction degree of polarization Py is 99.9% or more.

[6] The polarizer according to [5], wherein the polarizer layer is formed on one side of the protective film via a pressure-sensitive adhesive layer or an adhesive layer.

[7] The polarizer according to [5] or [6], wherein the polarizer layer is uniaxially stretched at a stretching ratio exceeding 5 times.

[8] A method for producing a polarizing laminated film according to any one of [1] to [4], wherein a resin layer made of a polyvinyl alcohol resin having a saponification degree of 99.0 mol% or less is formed on one side of a base film A resin layer forming step of obtaining a laminated film, a stretching step of obtaining a stretched film by uniaxially stretching the laminated film at a stretching magnification of more than 5 times, and a step of dying the resin layer of the stretched film with a dichroic dye to form a polarizer layer A method for producing a polarizing laminated film comprising a dyeing step.

[9] A method for producing a polarizing plate according to any one of [5] to [8], wherein a resin layer made of a polyvinyl alcohol resin having a saponification degree of 99.0 mol% or less is formed on one side of a base film, A stretching step of obtaining a stretched film by uniaxially stretching the laminated film at a stretching magnification of more than 5 times; a step of dying the resin layer of the stretched film with a dichroic dye to form a polarizer layer; A bonding step of bonding a protective film to a surface of the polarizing layer opposite to the surface on the base film side of the polarizing laminated film in the polarizing laminated film to obtain a multilayered film; a peeling step of peeling the base film from the multilayered film And a polarizing plate.

According to the present invention, it is possible to provide a thin polarizing plate capable of providing a display of a good contrast ratio in a liquid crystal display and a polarizing laminated film used therefor. Further, according to the polarizing plate or the method for producing a polarizing laminated film of the present invention, a resin layer made of a polyvinyl alcohol resin having a degree of saponification of 99.0 mol% or less is formed on the surface of the base film, By uniaxially stretching, an advantageous effect of obtaining a good dyeing speed in the dyeing step in the succeeding step is exhibited.

1 is a schematic sectional view showing an example of a basic layer structure of a polarizing laminated film according to the present invention.
2 is a schematic sectional view showing an example of a basic layer structure of a polarizing plate according to the present invention.
3 is a flowchart showing an embodiment of a method for producing a polarizing laminated film shown in Fig.
Fig. 4 is a flowchart showing one embodiment of the method for producing the polarizing plate shown in Fig. 2. Fig.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

≪ Constitution of Polarizing Laminated Film >

1 is a schematic sectional view showing an example of a basic layer structure of a polarizing laminated film according to the present invention. The polarizing laminated film 10 includes a base film 11 and a polarizer layer 12 formed on one side of the base film 11. The polarizer layer 12 is formed on one side of the base film 11, The polarizer layer 12 is formed of a polyvinyl alcohol resin having a thickness of 10 mu m or less and having a dichroic dye adsorbed and oriented. The saponification degree of the polyvinyl alcohol resin is 99.0 mol% or less.

The visual sensitivity correction Ty of the polarizing laminated film 10 is 40% or more and the visibility correction polarization degree Py is 99.9% or more. The polarizing laminated film 10 can be used as a polarizing plate. When the polarizing laminated film 10 has the above-described optical characteristics, a display having a good contrast ratio can be obtained when the polarizing laminated film 10 is used for a polarizing plate of a liquid crystal display device.

The visual sensitivity-corrected single-unit transmittance (Ty) was obtained by determining the MD transmittance and the TD transmittance of the polarizing laminated film or the polarizing plate within a wavelength range of 380 nm to 780 nm, and based on the following formula (1) Can be obtained by calculating the mass transmittance and by performing visibility correction using the second view field (C light source) of JIS Z 8701.

The visual sensitivity correction polarized light Py is obtained by calculating the MD transmittance and the TD transmittance in the same manner as described above and calculating the degree of polarization (%) at each wavelength based on the following formula (2) .

The "MD transmittance" is the transmittance when the polarizing direction of the polarizing plate sample is made parallel to the direction of the polarized light coming from the Glan Thompson prism. In the formulas (1) and (2), "MD" The term " TD transmittance " means the transmittance in the case where the direction of polarization from the Glan Thomson prism and the polarizing plate sample are orthogonal to the transmission axis, and is expressed by "TD" in the formulas (1) and (2). The MD transmittance, and the TD transmittance can be measured by a spectrophotometer having an integral sphere.

(%) = (MD + TD) / 2 Equation (1)

(%) = {(MD-TD) / (MD + TD)} 100 [

Hereinafter, each component will be described in detail.

[Base film]

As the material of the base film 11 used in the present invention, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, stretchability and the like is used. Specific examples of such thermoplastic resins include cellulose ester resins such as cellulose triacetate, polyester resins, polyether sulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, (Meth) acrylic resins, cyclic polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof.

As the material of the base film, it is preferable that at least one selected from the group consisting of a cellulose ester resin, a polyolefin resin, a cyclic polyolefin resin and a (meth) acrylic resin is included.

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.

Of these, cellulose triacetate is particularly preferable. Many products of cellulose triacetate are commercially available and are advantageous in terms of availability and cost. Examples of commercially available products of cellulose triacetate include Fuji Tack (registered trademark) TD80 (manufactured by Fuji Film), Fuji Tack (registered trademark) TD80UF (manufactured by Fuji Film), Fuji Tack (registered trademark) TD80UZ Ltd.), KC4UY (manufactured by Konica Minolta Opt.), And the like can be given as examples of the curable resin composition of the present invention.

Examples of the polyolefin-based resin include polyethylene and polypropylene. When a base film made of polypropylene is used, it is preferable that the base film can be stably stretched at a high magnification. As the cyclic polyolefin-based resin, a norbornene-based resin is preferably used.

The cyclic polyolefin-based resin is a generic name of a resin that is polymerized using a cyclic olefin as a polymerization unit, and examples thereof include resins described in JPH01-240517-A, JPH03-14882-A, JPH03-122137-A . Specific examples thereof include ring-opened (co) polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of cyclic olefins and? -Olefins such as ethylene and propylene (typically, random copolymers) and unsaturated carboxylic acids Graft polymers modified with derivatives thereof, and hydrides thereof. Specific examples of the cyclic olefin include norbornene monomers.

Various products are commercially available as the cyclic polyolefin-based resin. Specific examples thereof include: Topas (registered trademark) (manufactured by Ticona), ATON (registered trademark) (manufactured by JSR Corporation), ZEONOR (registered trademark) (manufactured by Nippon Zeon Corporation), Zeonex ZEONEX (registered trademark) (manufactured by Nippon Zeon Co., Ltd.) and APEL (registered trademark) (manufactured by Mitsui Chemicals, Inc.).

As the (meth) acrylic resin, any suitable (meth) acrylic resin may be employed. Examples thereof include poly (meth) acrylate esters such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymers, methyl methacrylate- (meth) acrylic acid ester copolymers, methyl methacrylate- (Meth) acrylic acid copolymer, a (meth) acrylic acid methyl-styrene copolymer (MS resin and the like), a polymer having an alicyclic hydrocarbon group (for example, a methacrylic acid methyl-methacrylic acid cyclohexyl copolymer, Methyl (meth) acrylate norbornyl copolymer, and the like).

Preferably, poly (meth) acrylate C1-6 alkyl such as poly (meth) acrylate is exemplified. As the (meth) acrylic resin, a methyl methacrylate resin having a main component (50 to 100 wt%, preferably 70 to 100 wt%) of methyl methacrylate is used.

In addition to the thermoplastic resin, any appropriate additives may be added to the base film 11. Examples of such an additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a releasing agent, a coloring inhibitor, a flame retardant, a nucleating agent, an antistatic agent, a pigment and a colorant. The content of the thermoplastic resin exemplified above in the base film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, particularly preferably 70 to 97% by weight %to be. When the content of the thermoplastic resin in the base film is less than 50% by weight, high transparency and the like inherently possessed by the thermoplastic resin may not be sufficiently manifested.

The thickness of the base film 11 can be appropriately determined, but is generally from 1 to 500 mu m, more preferably from 1 to 300 mu m, further preferably from 5 to 200 mu m in terms of workability such as strength and handling properties desirable. The thickness of the base film 11 is most preferably 5 to 150 mu m.

The base film 11 may be subjected to a corona treatment, a plasma treatment, a flame treatment, or the like on at least the surface of the base film 11 on the side where the polarizer layer 12 is formed, in order to improve the adhesion with the polarizer layer 12. In order to improve the adhesion, a thin layer such as a primer layer may be formed on the surface of the base film 11 on which the polarizer layer 12 is formed.

[Polarizer layer]

Specifically, the polarizer layer 12 is formed by adsorbing and orienting a dichroic dye in a uniaxially stretched polyvinyl alcohol-based resin layer. As the polyvinyl alcohol-based resin, a saponified polyvinyl acetate-based resin can be used. Examples of the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers with other monomers copolymerizable with vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

The saponification degree of the polyvinyl alcohol resin is 99.0 mol% or less. In the present invention, a polyvinyl alcohol resin having a degree of saponification of not more than 99.0 mol% is used, because a constant dyeing speed can be maintained even when uniaxial stretching exceeding 5 times is performed, There is an advantage that the polarizing laminated film can be efficiently produced. On the other hand, when a polyvinyl alcohol resin having a degree of saponification of more than 99.0 mol% is used, the dyeing speed is remarkably retarded, and a polarizing laminated film having sufficient polarization performance may not be obtained. There is a case where a problem of requiring a time which is several times as many as usual is generated.

The saponification degree of the polyvinyl alcohol resin is preferably 90 mol% or more, more preferably 94 mol% or more. If the degree of saponification is less than 90 mol%, the strength such as water resistance may not be sufficient.

The term "saponification degree" as used herein refers to the ratio of the acetic acid group contained in the polyvinyl acetate resin as the raw material of the polyvinyl alcohol resin to the hydroxyl group by the saponification process as a unit ratio (mol%) and is a numerical value defined by the following formula . It can be obtained by the method prescribed in JIS K 6726 (1994).

Saponification degree (mol%) = (number of hydroxyl groups) / (number of hydroxyl groups + number of acetic acid groups) x 100

The higher the degree of saponification, the higher the proportion of hydroxyl groups, that is, the lower the proportion of acetic acid groups that inhibit crystallization. The polyvinyl alcohol resin used in the present invention is not particularly limited as long as the degree of saponification is 99.0 mol% or less and may be a modified polyvinyl alcohol partially modified. For example, the polyvinyl alcohol resin may be modified by several percent of an unsaturated carboxylic acid such as olefin such as ethylene or propylene, acrylic acid, methacrylic acid or crotonic acid, an alkyl ester of unsaturated carboxylic acid, . The average degree of polymerization of the polyvinyl alcohol resin is not particularly limited, but is preferably 100 to 10,000, more preferably 1,500 to 10,000.

PVA 124 (saponification degree: 98.0 to 99.0 mol%), PVA117 (saponification degree: 98.0 to 99.0 mol%) and PVA 624 (saponification degree: 95.0 mol%) manufactured by Kuraray Co., Ltd. were used as the polyvinyl alcohol- To 96.0 mol%) and PVA 617 (saponification degree: 94.5 to 95.5 mol%); AH-26 (saponification degree: 97.0 to 98.8 mol%), AH-22 (saponification degree: 97.5 to 98.5 mol%) and NH-18 (saponification degree: 98.0 to 99.0 mol%) manufactured by Nippon Seika Kagakukyo Co., ) And N-300 (saponification degree: 98.0 to 99.0 mol%); (Degree of saponification: 98.0 to 99.0 mol%) and JF-17L (saponification degree: 98.0 to 99.0 mol%) and JF-20 (saponification degree: 98.0 to 99.0 mol%) of Nippon SAKUBI- ), Which can be preferably used in the present invention.

A film of such a polyvinyl alcohol resin constitutes the polarizer layer 12 according to the present invention. The method of forming the polyvinyl alcohol resin is not particularly limited and the film can be formed by a known method. From the viewpoint of easily obtaining the polarizer layer 12 having a desired thickness, a solution of the polyvinyl alcohol- It is preferable to coat the film 11 to form a film. The polarizer layer 12 is uniaxially stretched at a draw magnification of preferably not less than 5 times, more preferably not less than 5 times but not more than 17 times.

In the polarizer layer 12, a dichroic dye is adsorbed and oriented on the polyvinyl alcohol resin as described above. The thickness of the polarizer layer 12 is 10 占 퐉 or less, preferably 7 占 퐉 or less. By setting the thickness of the polarizer layer 12 to 10 m or less, a thin polarizing laminated film can be formed.

≪ Configuration of Polarizer &

2 is a schematic cross-sectional view showing an example of a basic layer structure of a polarizing plate according to the present invention. The polarizing plate 13 includes a protective film 14 and a polarizer layer 12 formed on one side of the protective film 14. [ The polarizer layer 12 is formed of a polyvinyl alcohol resin having a thickness of 10 mu m or less and having a dichroic dye adsorbed and oriented. The saponification degree of the polyvinyl alcohol resin is 99.0 mol% or less.

The visible light transmittance corrected Ty of the polarizing plate 13 is 40% or more, and the visual sensitivity correction polarity Py is 99.9% or more. The polarizing plate 13 can be used as a polarizing plate of a liquid crystal display device. When the polarizing plate 13 has the above-described optical characteristics, a good contrast ratio display can be obtained when the polarizing plate 13 is used as a polarizing plate of a liquid crystal display.

In the polarizing plate 13, the protective film 14 and the polarizer layer 12 are bonded to each other via, for example, a pressure-sensitive adhesive layer or an adhesive layer not shown in Fig. Hereinafter, each component will be described in detail.

[Protection film]

The protective film 14 may be a simple protective film having no optical function, and may be a protective film having optical functions such as a retardation film and a brightness enhancement film. Examples of the material of the protective film 14 include, but are not limited to, a cyclic polyolefin resin film, a cellulose acetate resin film made of a resin such as triacetylcellulose or diacetylcellulose, polyethylene terephthalate, polyethylene naphthalate, A polyester resin film made of a resin such as polybutylene terephthalate, a polycarbonate resin film, an acrylic resin film, a polypropylene resin film, and the like.

As the cyclic polyolefin-based resin, suitable commercially available products such as TOPAS (registered trademark) (manufactured by Ticona), ATON (registered trademark) (manufactured by JSR Corporation), ZEONOR (registered trademark) ZEONEX (manufactured by Nippon Zeon Co., Ltd.) and APEL (registered trademark) manufactured by Mitsui Chemicals, Inc. can be preferably used. When a film of such an annular polyolefin-based resin is formed into a film, known methods such as a solvent casting method and a melt extrusion method are suitably used. In addition, pre-formed films such as Essen (registered trademark) (manufactured by Sekisui Chemical Co., Ltd.), SCA40 (manufactured by Sekisui Chemical Co., Ltd.) and Zeonoa (registered trademark) A commercial product of a film made of a cyclic polyolefin resin may be used.

The cyclic polyolefin-based resin film may be uniaxially stretched or biaxially stretched. By stretching, an arbitrary retardation value can be imparted to the cyclic polyolefin-based resin film. The stretching is usually carried out while releasing the film roll, and is stretched in the heating direction in the heating direction, the direction perpendicular to the traveling direction of the roll, 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 to the glass transition temperature + 100 ° C. The magnification of the stretching is usually 1.1 to 6 times, preferably 1.1 to 3.5 times in one direction.

Since the surface activity of the cyclic polyolefin-based resin film is generally inferior, the surface to be bonded to the polarizing film is preferably subjected to surface treatment such as plasma treatment, corona treatment, ultraviolet ray irradiation treatment, frame (flame) treatment and saponification treatment Do. Among them, a plasma treatment and a corona treatment which can be performed relatively easily are preferable.

As the cellulose acetate based resin film, suitable commercially available products such as Fuji Tack (registered trademark) TD80 (manufactured by Fuji Film), Fuji Tack (registered trademark) TD80UF (manufactured by Fuji Film) KC4UY (manufactured by KONICA MINOLTA OPT Co., Ltd.), KC8UX2M (manufactured by Konica Minolta Optical Co., Ltd.), and KC4UY (manufactured by Konica Minolta Optical Co., Ltd.) Can be preferably used.

A liquid crystal layer or the like may be formed on the surface of the cellulose acetate-based resin film in order to improve the viewing angle characteristics. Further, in order to impart a phase difference, a cellulose acetate-based resin film may be stretched. The cellulose acetate-based resin film is usually subjected to saponification treatment in order to improve the adhesion with the polarizing film. As the saponification treatment, a method of immersing in an aqueous alkaline solution such as sodium hydroxide or potassium hydroxide can be employed.

On the surface of the protective film 14 as described above, an optical layer such as a hard coat layer, an antiglare layer, and an antireflection layer may be formed. The method of forming these optical layers on the surface of the protective film is not particularly limited and a known method can be used.

The thickness of the protective film 14 is preferably as thin as possible from the viewpoint of thinning, more preferably 88 탆 or less, and more preferably 48 탆 or less. On the contrary, when the thickness is excessively thin, the strength is lowered and the workability is deteriorated. Therefore, it is preferably 5 탆 or more.

[Polarizer layer]

The polarizer layer 12 may have the same structure as the polarizer layer 12 of the polarizing laminated film 10 described above.

[Pressure sensitive adhesive layer]

The pressure sensitive adhesive to be used for bonding the protective film 14 and the polarizer layer 12 is generally composed of an acrylic resin, a styrene resin, a silicone resin or the like as a base polymer and isocyanate compounds, epoxy compounds, aziridine compounds, Of a crosslinking agent is added.

It is also possible to use a pressure-sensitive adhesive layer containing fine particles and exhibiting light scattering properties.

The thickness of the pressure-sensitive adhesive layer is preferably from 1 to 40 占 퐉, but it is preferably thinly coated, more preferably from 3 to 25 占 퐉, within a range not deteriorating workability and durability characteristics. When the thickness is 3 to 25 占 퐉, the film has good processability and a preferable thickness for suppressing the dimensional change of the polarizing film. If the pressure-sensitive adhesive layer is less than 1 占 퐉, the pressure-sensitive adhesive property is deteriorated, and if it exceeds 40 占 퐉, the pressure-sensitive adhesive is likely to be discharged.

In the method of bonding the protective film 14 to the polarizer layer 12 by a pressure-sensitive adhesive, the pressure-sensitive adhesive layer may be formed on the surface of the protective film 14 and then bonded to the polarizer layer 12, After the pressure-sensitive adhesive layer is formed, the protective film 14 may be bonded thereto.

The method of forming the pressure-sensitive adhesive layer is not particularly limited, and a solution containing each component including the base polymer is applied and dried on the surface of the protective film 14 or the surface of the polarizer layer 12 to form a pressure- Alternatively, the protective film 14 and the polarizer layer 12 may be bonded to each other. Alternatively, a pressure-sensitive adhesive layer may be formed on the separator and transferred to the protective film 14 surface or the polarizer layer 12 surface. When the pressure-sensitive adhesive layer is formed on the surface of the protective film 14 or the polarizer layer 12, the pressure-sensitive adhesive layer may be adhered to one side or both sides of the protective film 14 or the polarizer layer 12 or the pressure- Corona treatment may be carried out.

[Adhesive layer]

Examples of the adhesive used for bonding the protective film 14 and the polarizer layer 12 include an aqueous adhesive using, for example, a polyvinyl alcohol resin aqueous solution, a water-based liquid type urethane emulsion adhesive, and the like. When a cellulose acetate film subjected to hydrophilization treatment such as saponification treatment is used as the protective film 14, a polyvinyl alcohol resin aqueous solution is preferably used as an aqueous adhesive for bonding with the polarizer layer 12. The polyvinyl alcohol resin used as the adhesive includes a vinyl alcohol homopolymer obtained by saponifying a polyvinyl acetate which is a homopolymer of vinyl acetate, a vinyl alcohol homopolymer obtained by saponifying a copolymer of vinyl acetate and another monomer capable of copolymerization with the vinyl alcohol, Based copolymers, and further modified polyvinyl alcohol polymers obtained by partially modifying hydroxyl groups thereof. As the water-based adhesive, polyaldehyde, a water-soluble epoxy compound, a melamine compound, a zirconia compound, a zinc compound or the like may be added as an additive. When such an aqueous adhesive is used, the adhesive layer obtained therefrom usually has a size of 1 mu m or less, and even if a cross section is observed with an ordinary optical microscope, the adhesive layer is practically not observed.

The method of bonding the polarizer layer 12 and the protective film 14 using an aqueous adhesive is not particularly limited and the adhesive may be uniformly applied to the surface of the polarizer layer 12 and / And a method in which another film is laid on the coated surface and then dried by pressing with a roll or the like. Normally, the adhesive is applied at a temperature of 15 to 40 캜 after its preparation, and the bonding temperature is usually in the range of 15 to 30 캜.

When an aqueous adhesive is used, the polarizer layer 12 and the protective film 14 are bonded together and then dried to remove water contained in the aqueous adhesive. The temperature of the drying furnace is preferably 30 ° C to 90 ° C. If the temperature is lower than 30 占 폚, the adhesion surface of the polarizer layer 12 and the protective film 14 tends to peel off easily. If it is 90 DEG C or higher, there is a fear that the optical performance is deteriorated by heat. The drying time can be 10 to 1000 seconds, and is preferably 60 to 750 seconds, and more preferably 150 to 600 seconds from the viewpoint of productivity.

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

Further, a photo-curable adhesive may be used as the adhesive when the polarizer layer 12 and the protective film 14 are bonded. The photo-curable adhesive includes, for example, a mixture of a photo-curable epoxy resin and a photo cationic polymerization initiator.

As a method for bonding the polarizer layer 12 and the protective film 14 with a photo-curing adhesive, conventionally known methods can be used. For example, a flexible method, a Meyer bar coat method, a gravure coat method, a comma coater method A doctor plate method, a die coating method, a dip coating method, a spraying method, or the like, an adhesive is applied to the bonding surface of the polarizer layer 12 and / or the protective film 14, and both are overlapped. The flexible method is a method in which a polarizer layer 12 or a protective film 14 as an object to be coated is moved in a substantially vertical direction, a substantially horizontal direction, or an inclined direction therebetween, to be.

An adhesive is applied to the surface of the polarizer layer 12 or the protective film 14 and then the polarizer layer 12 and the protective film 14 are bonded to each other with a nip roll or the like interposed therebetween via an adhesive application surface. An adhesive is dropped between the polarizer layer 12 and the protective film 14 in a state where the polarizer layer 12 and the protective film 14 are superimposed on each other and then the laminate is pressed with a roll or the like, Can also be preferably used. In this case, metal, rubber, or the like can be used as the material of the roll. Further, a method of dropping an adhesive between the polarizer layer 12 and the protective film 14, passing the film between the rolls and the rolls, and pressing and spreading the adhesive are preferably employed. In this case, these rolls may be made of the same material or different materials. The thickness of the adhesive layer after bonding using the nip roll or the like before drying or curing is preferably 5 m or less and 0.01 m or more.

A surface treatment such as a plasma treatment, a corona treatment, an ultraviolet ray irradiation treatment, a frame (flame) treatment or a saponification treatment is suitably applied to the adhesive surface of the polarizer layer 12 and / or the protective film 14 May be performed. As the saponification treatment, there may be mentioned a method of immersing in an aqueous solution of an alkali such as sodium hydroxide or potassium hydroxide.

When a photo-curable resin is used as the adhesive, the polarizing layer 12 and the protective film 14 are bonded together, and then the active-energy ray is irradiated to cure the photo-curable adhesive. A light source of an active energy ray is not particularly limited, but an active energy ray having a light emission distribution at a wavelength of 400 nm or less is preferable. Specifically, a low energy mercury lamp, medium pressure mercury lamp, high pressure mercury lamp, ultra high pressure mercury lamp, A wave excitation mercury lamp, a metal halide lamp and the like are preferably used.

The light irradiation intensity for the photo-curable adhesive is appropriately determined depending on the composition of the photo-curable adhesive and is not particularly limited, but it is preferable that the irradiation intensity in the wavelength range effective for activation of the polymerization initiator is 0.1 to 6000 mW / cm 2. When the irradiation intensity is not less than 0.1 mW / cm 2, the reaction time is not excessively long. When the irradiation intensity is not more than 6000 mW / cm 2, the heat radiated from the light source and the heat generated during curing of the photo-curing adhesive deteriorate the yellowing of the epoxy resin, . The light irradiation time for the photo-curable adhesive is not particularly limited as long as it is applied in accordance with the photo-curing adhesive to be cured, but it is preferable that the accumulated light quantity represented by the product of the irradiation intensity and the irradiation time is set to 10 to 10,000 mJ / Do. When the total amount of light for the photo-curable adhesive is 10 mJ / cm 2 or more, a sufficient amount of active species derived from the polymerization initiator can be generated sufficiently to allow the curing reaction to proceed more surely. When the amount is less than 10000 mJ / cm 2, So that good productivity can be maintained. The thickness of the adhesive layer after irradiation with active energy rays is usually about 0.001 to 5 mu m, preferably 0.01 mu m or more and 2 mu m or less, more preferably 0.01 mu m or more and 1 mu m or less.

When the photo-curing adhesive is cured by irradiation of an active energy ray, the curing is performed under such a condition that various functions of the polarizing plate are not deteriorated, such as the polarization degree, transmittance and hue of the polarizer layer 12, and transparency of the protective film 14 .

[Other optical layers]

The polarizing plate of the present invention produced as described above can be used as a polarizing plate in which other optical layers are laminated in practical use. Further, the protective film 14 may have the function of the optical layer. Examples of other optical layers include a reflective polarizing film that transmits polarized light of a certain type and reflects polarized light exhibiting properties opposite to the polarized light, a film having an antireflection function having a concavo-convex shape on the surface, A reflective film having a reflective function on its surface, a transflective film having a reflective function and a transmissive function, and a viewing angle compensating film.

Examples of commercially available products that correspond to a reflective polarizing film that transmits polarized light of a certain kind and reflect polarized light exhibiting properties opposite to that of the polarized light include DBEF (available from 3M Company, available from Sumitomo 3M Ltd.) APF (available from 3M, available from Sumitomo 3M Ltd.). Examples of the viewing angle compensation film include an optical compensation film on which a liquid crystal compound is applied and aligned on a substrate surface, a retardation film made of a polycarbonate resin, and a retardation film made of a cyclic polyolefin resin. Examples of commercially available products corresponding to optical compensation films on which a liquid crystal compound is applied and aligned on the surface of a substrate include WV films (manufactured by Fuji Film), NH films (manufactured by Shin-Nippon Sekiyu Co., Ltd.), NR films (Manufactured by Nippon Sekiyu Co., Ltd.). Examples of commercially available products corresponding to the retardation film made of the cyclic polyolefin resin include Aton (registered trademark) film (manufactured by JSR Corporation), Eschina (registered trademark) (manufactured by Sekisui Chemical Co., Ltd.) (Registered trademark) film (manufactured by Optesis Co., Ltd.).

≪ Method for producing a polarizing laminated film &

Fig. 3 is a flowchart showing one embodiment of the method for producing the polarizing laminated film 10 shown in Fig. According to this method, the method for producing the polarizing laminated film 10 is a method of forming a resin layer made of a polyvinyl alcohol resin having a saponification degree of 99.0 mol% or less on one surface of the base film 11 to form a laminated film A stretching step S20 for forming a stretched film by subjecting the laminated film to a uniaxial stretching process at a stretching magnification of more than 5 times, a step for forming a stretched film by dying the resin layer of the stretched film with a dichroic dye, (S30) for obtaining a polarizing laminated film (10) as a base film (12) in this order. The resin layer forming step (S10), the stretching step (S20) and the dyeing step (S30) are the same as the corresponding steps in the polarizing plate manufacturing method described later.

The laminated film obtained by this manufacturing method is a polarizing laminated film 10 provided with a polarizer layer 12 having a thickness of 10 mu m or less on a stretched base film 11. [ This may be used as the polarizing plate as it is or as an intermediate product for transferring the polarizing layer 12 to the protective film as described later.

≪ Polarizing plate production method >

Fig. 4 is a flowchart showing an embodiment of a manufacturing method of the polarizing plate 13 shown in Fig.

According to this method, the polarizing plate 13 is manufactured by a resin layer forming step (S10) in which a resin layer made of a polyvinyl alcohol resin having a saponification degree of 99.0 mol% or less is formed on one surface of a base film to form a laminated film, , A stretching step (S20) of applying a uniaxial stretching treatment to the laminated film at a draw ratio of more than 5 times to obtain a stretched film, a dyeing step (S20) of obtaining a polarizing laminated film as a polarizing layer 12 S30) are carried out in this order and then a protective film 14 is bonded to a surface of the polarizing layer 12 of the polarizing laminated film opposite to the surface on the base film 11 side to obtain a multilayer film S40), and a peeling step (S50) of peeling the base film 11 from the multi-layer film.

The polarizing plate 13 obtained by this manufacturing method is a polarizing plate 13 provided with a polarizing layer 12 having a thickness of 10 m or less on the protective film 14. The polarizing plate 13 can be used, for example, by bonding to another optical film or a liquid crystal cell via a pressure sensitive adhesive.

Hereinafter, each step of S10 to S50 in Fig. 3 and Fig. 4 will be described in detail. Further, the respective steps of Fig. 3 and S10 to S30 of Fig. 4 are the same step.

[Resin layer forming step (S10)]

Here, a resin layer made of polyvinyl alcohol resin is formed on one surface of the base film.

Materials suitable for the base film are as described in the description of the constitution of the polarizing laminated film. In the present embodiment, it is preferable to use a base film having a melting point of 110 ° C or higher so that it can be stretched in a temperature range suitable for stretching the polyvinyl alcohol resin. Preferably, those having a melting point of 130 ° C or higher are used. If the melting point of the base film is less than 110 캜, the base film tends to be melted in the stretching step (S20) described later, so that the stretching temperature can not be sufficiently increased and stretching exceeding 5 times becomes difficult. The melting point of the base film is a value measured at a heating rate of 10 占 폚 / min based on ISO3146.

The material of the polyvinyl alcohol resin suitable for forming the resin layer is as described in the description of the constitution of the polarizing laminated film. The thickness of the resin layer to be formed is preferably more than 3 占 퐉 and 30 占 퐉 or less, more preferably 5 to 20 占 퐉. If the thickness is less than 3 탆, the resulting film becomes too thin after stretching to significantly deteriorate the dyeability. If it exceeds 30 탆, the thickness of the finally obtained polarizer layer may exceed 10 탆.

The resin layer is preferably formed by coating a polyvinyl alcohol resin solution obtained by dissolving a polyvinyl alcohol resin powder in a good solvent on one surface of a base film and drying the solvent by evaporation. By forming the resin layer in this way, it becomes possible to form the resin layer thin. Examples of the method for coating a polyvinyl alcohol resin solution on a base film include a roll coating method such as wire bar coating method, reverse coating and gravure coating, a die coating method, a comma coating method, a lip coating method, a spin coating method, Method, a fountain coating method, a dipping method, a spraying method, and the like can be suitably selected and employed by a known method. The drying temperature is, for example, 50 to 200 占 폚, preferably 60 to 150 占 폚. The drying time is, for example, 2 to 20 minutes.

The resin layer in the present embodiment can also be formed by adhering an original film made of a polyvinyl alcohol resin on one surface of a base film.

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

[Stretching step (S20)]

Here, a laminated film composed of a base film and a resin layer is uniaxially stretched so as to have a stretching magnification exceeding 5 times the original length of the laminated film to obtain a stretched film. Preferably, uniaxial stretching is performed so that the stretching magnification is 5 times to 17 times or less. More preferably not more than 5 times but not more than 8 times. If the stretching magnification is 5 times or less, the resin layer made of polyvinyl alcohol resin is not sufficiently oriented, and as a result, the degree of polarization of the polarizer layer does not become sufficiently high. On the other hand, if the stretching magnification exceeds 17 times, the laminated film tends to be broken at the time of stretching, and the thickness of the stretched film becomes thinner than necessary, which may lower the workability and handling property in subsequent steps. The stretching process in the stretching process (S20) is not limited to stretching in one stage but may be performed in multiple stages. In the case of multi-step drawing, the drawing process is carried out so that the total of the front ends of the drawing process becomes a drawing magnification exceeding 5 times.

In the stretching step (S20) in the present embodiment, it is preferable to perform the longitudinal stretching treatment in the longitudinal direction of the laminated film. However, in the case where the polarizing performance is not so required, It may be stretched. Examples of the longitudinal stretching method include an inter-roll stretching method, a compression stretching method, and a stretching method using a tenter. The stretching treatment is not limited to the longitudinal stretching treatment, but may be an oblique stretching treatment or the like. It is also preferable to be free-end uniaxial stretching.

The stretching treatment can be carried out by any of a wet stretching method and a dry stretching method, but the use of a dry stretching method is preferable in that the temperature for stretching the laminated film can be selected from a wide range.

In the present embodiment, it is preferable that the stretching treatment is performed in a temperature range of -30 캜 to + 5 캜 of the melting point of the base film. More preferably, the stretching treatment is performed at a temperature ranging from -25 ° C to the melting point of the base film. When the stretching temperature is lower than -30 캜 of the melting point of the base film 11, high-magnification stretching exceeding 5 times becomes difficult. If the stretching temperature exceeds +5 캜 of the melting point of the base film, stretching becomes difficult due to melting of the base film, which is not preferable. The stretching temperature is within the above range, more preferably 120 deg. When the stretching temperature is 120 DEG C or more, even if the stretching ratio is higher than 5 times, the stretching process is not accompanied with difficulty. The temperature adjustment of the stretching treatment is usually carried out by adjusting the temperature of the heating furnace.

[Dyeing process (S30)]

Here, the resin layer of the stretched film is dyed with a dichroic dye. Examples of the dichroic dye include iodine and organic dyes. Examples of organic dyes include red dyes 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, Violet LB, B, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Kongogred, Brilliant Violet BK, Supra Blue G, Supra Blue GL, Supra Orange GL, Direct Sky Blue, Direct First Orange S, First Black and the like can be used. 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 in a solution (dyeing solution) containing the dichroic dye. As the dyeing solution, a solution obtained by dissolving the dichroic dye in a solvent can be used. As a solvent for the dyeing solution, water is generally used, but an organic solvent having compatibility with water may be further added. The concentration of the dichroic dye is preferably 0.01 to 10 wt%, more preferably 0.02 to 7 wt%, and particularly preferably 0.025 to 5 wt%.

When iodine is used as the dichroic dye, it is preferable to further 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, barium iodide, calcium iodide, tin iodide, titanium iodide and the like. The addition ratio of these iodides is preferably 0.01 to 10% by weight in the dyeing solution. Among iodides, it is preferable to add potassium iodide. When potassium iodide is added, the ratio of iodine to potassium iodide is preferably in the range of 1: 5 to 1: 100, more preferably in the range of 1: 6 to 1:80, more preferably 1: 7 to 1: 70.

The immersing time of the stretched film in the dyeing solution is not particularly limited, but it is preferably in the range of 15 seconds to 15 minutes, and more preferably in the range of 1 to 3 minutes. The temperature of the dyeing solution is preferably in the range of 10 to 60 占 폚, and more preferably in the range of 20 to 40 占 폚.

In the dyeing step, the dyeing can be followed by a crosslinking treatment. The crosslinking treatment can be performed, for example, by immersing the stretched film in a solution (crosslinking solution) containing a crosslinking agent. As the crosslinking agent, conventionally known materials can be used. Examples thereof include boron compounds such as boric acid and borax, and glyoxal and glutaraldehyde. These may be used alone or in combination of two or more.

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, but an organic solvent having compatibility with water may be further contained. The concentration of the cross-linking agent in the cross-linking solution is not limited to this, but is preferably in the range of 1 to 20 wt%, and more preferably in the range of 6 to 15 wt%.

Iodide may be added to the crosslinking solution. By adding iodide, the polarization characteristics in the plane of the resin layer can be made more uniform. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide and titanium iodide. The content of iodide is 0.05 to 15% by weight, more preferably 0.5 to 8% by weight.

The immersion time of the stretched film to the crosslinking solution is preferably 15 seconds to 20 minutes, more preferably 30 seconds to 15 minutes. The temperature of the crosslinking solution is preferably in the range of 10 to 80 캜.

Finally, it is preferable to carry out a washing step and a drying step. In the washing step, a water washing treatment can be performed. The water washing treatment can be usually carried out by immersing the drawn film in purified water such as ion-exchanged water or distilled water. The water washing temperature is usually in the range of 3 to 50 캜, preferably 4 to 20 캜. The immersion time is usually from 2 to 300 seconds, preferably from 3 seconds to 240 seconds.

The cleaning step may be a combination of a cleaning treatment with a iodide solution and a water washing treatment, or a solution in which a liquid alcohol such as methanol, ethanol, isopropyl alcohol, butanol, or propanol is blended.

It is preferable to carry out the drying step after the cleaning step. As the drying step, any appropriate method (for example, natural drying, air blow drying, heat drying) may be employed. For example, in the case of heat drying, the drying temperature is usually 20 to 95 占 폚, and the drying time is usually about 1 to 15 minutes. By the above-described dyeing step (S30), the resin layer has a function as a polarizer.

In the present specification, a laminate having a polarizer layer on a base film and a resin layer having a function as a polarizer is referred to as a polarizer layer is referred to as a polarizing laminated film.

In this embodiment, since the polyvinyl alcohol resin having a saponification degree of 99.0 mol% or less is used for the resin layer and the uniaxial stretching is performed at a stretching ratio exceeding 5 times in the stretching step (S20) S30), a good dyeing rate is maintained. In addition, the resin layer using a polyvinyl alcohol resin having a high degree of saponification tends to have a low dyeing speed in the dyeing step (S30), resulting in insufficient dyeing.

[Bonding step (S40)]

Here, a protective film is bonded to the surface of the polarizing layer on the side opposite to the surface on the base film side in the polarizing laminated film to obtain a multilayered film. Examples of the method of bonding the protective film include a method of bonding the polarizer layer 12 and the protective film 14 with a pressure sensitive adhesive, and a method of bonding the surface of the polarizer layer 12 and the protective film 14 with an adhesive. Materials suitable as the protective film are as described in the description of the constitution of the above-mentioned polarizing plate. A preferable method for bonding the polarizer layer 12 and the protective film 14 using a suitable adhesive, a material for the pressure-sensitive adhesive, and the use thereof is as described in the description of the constitution of the above-mentioned polarizing plate.

[Peeling step (S50)]

In the polarizing plate manufacturing method of this embodiment, as shown in Fig. 4, the peeling step (S50) is performed after the bonding step (S40) of bonding the protective film to the polarizing layer 12 of the polarizing laminated film. In the peeling step (S50), the base film is peeled from the multi-layer film. The method of peeling the base film is not particularly limited, and can be peeled off in the same manner as the peeling film peeling process performed in a polarizing plate to which a usual pressure-sensitive adhesive is applied. After the step of bonding the protective film (S40), the protective film may be peeled off as it is, or may be peeled once by setting the peeling step separately after winding it into a roll shape.

Example

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples.

Example 1

The polarizing plate shown in Fig. 2 was produced according to the manufacturing method shown in Fig.

(Substrate film)

As the base film, an unoriented polypropylene (PP) film (melting point: 163 占 폚) having a thickness of 110 占 퐉 was used.

(Primer layer forming step)

An aqueous solution having a concentration of 3% by weight was prepared by dissolving a polyvinyl alcohol powder (manufactured by Nihon Seika Kagakukyo Co., Ltd., average degree of polymerization: 1100, saponification degree: 99.5 mol%, trade name: Z-200) in hot water at 95 캜. 5 parts by weight of a crosslinking agent (trade name: Sumirez (registered trademark) resin 650, manufactured by Sumitomo Chemical Co., Ltd.) was mixed with 6 parts by weight of the polyvinyl alcohol powder.

The obtained mixed aqueous solution was coated on a corona-treated substrate film using a micro gravure coater and dried at 80 DEG C for 10 minutes to form a primer layer having a thickness of 0.2 mu m.

(Resin layer forming step)

A polyvinyl alcohol aqueous solution having a concentration of 8% by weight was prepared by dissolving polyvinyl alcohol powder (manufactured by Kuraray Co., Ltd., average degree of polymerization: 2400, degree of saponification: 98.0 to 99.0 mol%, trade name: PVA124) in hot water at 95 캜. The resulting aqueous solution was coated on the primer layer using a lip coater and dried at 80 DEG C for 20 minutes to produce a three-layer laminated film comprising a base film, a primer layer and a resin layer.

(Drawing step)

The laminated film was subjected to free end uniaxial stretching at 160 DEG C by 5.8 times using a tenter apparatus to obtain a stretched film. The thickness of the resin layer after stretching was 6.1 mu m.

(Dyeing process)

Thereafter, the stretched film was immersed in a warm bath at 60 DEG C for 60 seconds, dyed in a dyeing solution which is a mixed aqueous solution of iodine and potassium iodide at 30 DEG C for about 150 seconds, and then the excess iodine solution was washed with pure water at 10 DEG C I got it. Subsequently, the substrate was immersed in a crosslinking solution of a mixed aqueous solution of boric acid and potassium iodide at 76 DEG C for 600 seconds. Thereafter, it was washed with pure water at 10 캜 for 4 seconds, and finally dried at 50 캜 for 300 seconds. By the above steps, a polarizer layer was formed from the resin layer to obtain a polarizing laminated film. The mixing ratio of each solution is as follows.

<Dyeing solution>

Water: 100 parts by weight

Iodine: 0.6 parts by weight

Potassium iodide: 10 parts by weight

&Lt; Crosslinking solution &

Water: 100 parts by weight

Boric acid: 9.5 parts by weight

Potassium iodide: 5 parts by weight

(Bonding of protective film)

An aqueous solution having a concentration of 3% by weight was prepared by dissolving polyvinyl alcohol powder (manufactured by Kuraray Co., Ltd., average degree of polymerization 1800, trade name: KL-318) in hot water at 95 캜. 1 part by weight of a crosslinking agent (Sumirez (registered trademark) Resin 650, manufactured by Sumitomo Mogaka Co., Ltd.) was added to 2 parts by weight of polyvinyl alcohol powder to prepare an adhesive solution. The above-mentioned polyvinyl alcohol-based adhesive was applied to the surface of the polarizing layer of the polarizing laminated film opposite to the surface on the base film side, and then a protective film (TAC: KC4UY, manufactured by Konica Minolta Opt) was bonded, A polarizing plate composed of five layers of a protective film, an adhesive layer, a polarizer layer, a primer layer and a base film was obtained. The base film was peeled from the obtained polarizing plate. The base film was easily peeled off to obtain a polarizing plate composed of four layers of a protective film, an adhesive layer, a polarizer layer, and a primer layer. The thickness of the polarizer layer was 6.1 mu m.

Example 2

The same procedure as in Example 1 was carried out except that polyvinyl alcohol (polyvinyl alcohol powder (manufactured by Nihon Seika Kagaku Kogyo Co., Ltd., average degree of polymerization: 2200, degree of saponification: 97.5 to 98.5 mol%, trade name: AH-22) To give a stretched film. The thickness of the resin layer in the stretched film was 5.5 占 퐉. Further, a dyeing step, a bonding step, a peeling step and the like were carried out in the same manner as in Example 1 to obtain a polarizing plate of Example 2 comprising four layers of a protective film, an adhesive layer, a polarizer layer and a primer layer. The thickness of the polarizer layer was 5.6 탆.

Example 3

Except that a polyvinyl alcohol powder (manufactured by Nihon Sakubi Co., Ltd., average degree of polymerization: 2600, degree of saponification: 95.5 to 97.5 mol%, trade name: JM-26) was used as the polyvinyl alcohol used for the resin layer. A stretched film was obtained in the same manner. The thickness of the resin layer in the stretched film was 5.3 mu m. Further, a dyeing step, a bonding step, a peeling step and the like were carried out in the same manner as in Example 1 to obtain a polarizing plate of Example 3 having four layers of a protective film, an adhesive layer, a polarizer layer and a primer layer. The thickness of the polarizer layer was 5.3 탆.

Comparative Example 1

A stretched film was obtained in the same manner as in Example 1, except that polyvinyl alcohol used as a resin layer (manufactured by Kuraray Co., Ltd., average degree of polymerization: 1700, degree of saponification: 99.3 mol% or more, trade name: PVA117H) . The thickness of the resin layer in the stretched film was 6.3 mu m. Further, a dyeing step, a bonding step, a peeling step and the like were carried out in the same manner as in Example 1 to obtain a polarizing plate of Comparative Example 1 comprising four layers of a protective film, an adhesive layer, a polarizer layer and a primer layer. The thickness of the polarizer layer was 6.3 탆.

Comparative Example 2

As the polyvinyl alcohol used for the resin layer, a polyvinyl alcohol (manufactured by Kuraray Co., Ltd., average degree of polymerization of 2400, degree of saponification of 99.9 mol% or more, trade name: Kurarefopal VF-PS # 7500) , And that the stretching magnification in the stretching step was changed to 4.0 times, a stretched film was obtained in the same manner as in Example 1. [ The thickness of the resin layer in the stretched film was 6.7 mu m. Further, a dyeing step, a bonding step, a peeling step and the like were carried out in the same manner as in Example 1 to obtain a polarizing plate of Comparative Example 2 comprising four layers of a protective film, an adhesive layer, a polarizer layer and a primer layer. The thickness of the polarizer layer was 6.7 탆.

Comparative Example 3

Except that polyvinyl alcohol used in the resin layer (manufactured by Kuraray Co., Ltd., average polymerization degree: 2400, degree of saponification: 99.9 mol% or more, trade name: Kurarupo's VF-PS # 7500) was finely cut A stretched film was obtained in the same manner as in Example 1. The thickness of the resin layer in the stretched film was 6.3 mu m. Further, a dyeing step, a bonding step, a peeling step and the like were carried out in the same manner as in Example 1 to obtain a polarizing plate of Comparative Example 3 comprising four layers of a protective film, an adhesive layer, a polarizer layer and a primer layer. The thickness of the polarizer layer was 6.3 탆.

(Measurement of polarization performance)

The MD transmittance and the TD transmittance of the polarizing plate composed of the four layers of the protective film, the adhesive layer, the polarizer layer and the primer layer obtained by peeling the base film were measured with a spectrophotometer (V7100, manufactured by Nihon Bunko Co., Ltd.) . Based on the above equations (1) and (2), the simple transmittance and the polarization degree at each wavelength are calculated and the visual sensitivity correction is performed by the second visual field (C light source) of JIS Z 8701, And the visual sensitivity correction polarization degree Py were obtained. In the measurement of the polarizing plate, the side of the protective film was set to the detector side, and the apparatus was set so that light came from the side of the primer layer.

Table 1 shows the visual sensitivity-corrected single unit transmittance Ty and visual sensitivity correction polarization degree Py of the polarizing plate of Example 1 and Comparative Examples 1 to 3.

(Evaluation of mounting on a commercial mobile phone)

"AuEXILIM Ketai W53CA" (manufactured by CASIO KAN SANKYO CO., LTD.) Sold by KDDI Co., Ltd. was disassembled and the polarizing plate bonded above and below the liquid crystal cell was peeled off to take out the liquid crystal cell.

The polarizing plates obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were pasted on the top and bottom of the liquid crystal cell via a pressure sensitive adhesive. At this time, the absorption axis of the polarizing plate attached to the image side (viewer side) of the liquid crystal cell was arranged so as to be 170 degrees counterclockwise from the short side of the liquid crystal cell at the time when viewed from the viewer side. The absorption axis of the polarizing plate attached to the lower side (backlight side) of the liquid crystal cell was arranged so as to be 80 degrees counterclockwise from the short side of the liquid crystal cell when viewed from the viewer side. The arrangement angle is the same as the arrangement angle of the absorption axis of the original polarizing plate originally bonded to the liquid crystal cell.

Using a liquid crystal cell obtained by pasting the polarizing plates obtained in Examples 1 to 3 and Comparative Examples 1 to 3 upside down, the cellular phone was assembled again to display an image. The evaluation of the display state was performed by visually determining the clarity of the image in a general indoor environment and a dark room.

Table 1 shows the evaluation results of the polarizing plates of Examples 1 to 3 and Comparative Examples 1 to 3.

In Examples 1 to 3, a polyvinyl alcohol resin having a degree of saponification of 99.0 mol% or less is used and the stretching magnification is set to be 5 times or more. Therefore, even if the dyeing time is such as not to hinder normal production, Py. By using the obtained polarizing plate in a liquid crystal display, clear and good image display was achieved.

On the other hand, in Comparative Examples 1 and 3, a polyvinyl alcohol resin having a degree of saponification of more than 99.0 mol% was used and the stretching magnification was made to exceed 5 times, so that the dyeing time It can not be dyed sufficiently, and Py has a low value. When the obtained polarizing plate was used in a liquid crystal display device, an image was displayed with a low contrast ratio CR and lack of clarity.

Further, in Comparative Example 2, the polyvinyl alcohol resin having a degree of saponification of more than 99.0 mol% was used and the stretching magnification was set to 5 times or less. Therefore, the dyeing time sufficient for normal production would not be sufficient , But Py was low. When the obtained polarizing plate was used in a liquid crystal display device, an image was displayed with a low contrast ratio CR and lack of clarity.

10: Polishing laminated film 11: Base film
12: Polarizer layer 13: Polarizing plate
14: Protective film

Claims (7)

1. A polarizing plate comprising a base film and a polarizer layer formed on one side of the base film,
The polarizer layer is formed of a polyvinyl alcohol resin having a thickness of 10 mu m or less and having a dichroic dye adsorbed and oriented,
The saponification degree of the polyvinyl alcohol resin is 99.0 mol% or less,
A visual sensitivity transmittance Ty of 40% or more, a visual sensitivity correction polarization degree Py of 99.9% or more,
Wherein the polarizer layer is uniaxially stretched in the free state at a stretching magnification exceeding 5 times. The polarizing laminated film according to claim 1, which is used for a polarizing plate. The polarizing laminated film according to claim 1 or 2, wherein the polarizer layer is formed on one side of the base film via a primer layer. A protective film and a polarizer layer formed on one side of the protective film,
The polarizer layer is formed of a polyvinyl alcohol resin having a thickness of 10 mu m or less and having a dichroic dye adsorbed and oriented,
The saponification degree of the polyvinyl alcohol resin is 99.0 mol% or less,
The visual sensitivity-corrected single-beam transmittance Ty is not less than 40%, the visual sensitivity correction polarization degree Py is not less than 99.9%
Wherein the polarizer layer is uniaxially stretched at a stretch ratio exceeding 5 times. The polarizer according to claim 4, wherein the polarizer layer is formed on one side of the protective film via a pressure-sensitive adhesive layer or an adhesive layer. delete delete

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