KR101949182B1

KR101949182B1 - Dye-based polarizer and polarizing plate

Info

Publication number: KR101949182B1
Application number: KR1020147014328A
Authority: KR
Inventors: 노리아키 모치즈키
Original assignee: 니폰 가야꾸 가부시끼가이샤; 가부시키가이샤 폴라테크노
Priority date: 2012-03-19
Filing date: 2013-03-19
Publication date: 2019-02-18
Also published as: HK1201928A1; TW201344260A; JP6392665B2; CN104115042B; TWI551899B; JPWO2013141236A1; WO2013141236A1; CN104115042A; KR20140138589A

Abstract

[PROBLEMS] Development of a polarizing element which is a dye having excellent blue dye and has good polarization characteristics without using a raw material belonging to a specific chemical substance such as dianisidine.
[MEANS FOR SOLVING PROBLEMS] A polarizing element comprising a polyvinyl alcohol resin or a derivative thereof and a film containing a dichroic dye and stretched three times or more, wherein at least one of the dichroic dye is an azo compound represented by the formula (1) And the content of the azo compound represented by the formula (2) or a salt thereof in the polarizing element is 10% or less.

In the formulas, A represents a naphthyl group having a substituent, R represents a hydrogen atom or a methoxy group, and X represents a hydrogen atom, a hydroxyl group, a carboxy group, a methyl group, a methoxy group or a sulfo group.

Wherein A, R, and X have the same meanings as those in the formula (1).

Description

DYE-BASED POLARIZER AND POLARIZING PLATE

The present invention relates to a dye-based polarizing element and a polarizing plate using the same.

Polarizing elements are generally produced by adsorbing and orienting iodine or a dichroic dye, which is a dichroic dye, on a polyvinyl alcohol-based resin film. A protective film made of triacetyl cellulose or the like is bonded to at least one side of the polarizing element through an adhesive layer to form a polarizing plate and used for a liquid crystal display device or the like. A polarizing plate using iodine as a dichroic dye is called an iodine polarizing plate and a polarizing plate using a dichroic dye as a dichroic dye is called a dye-based polarizing plate. Among them, the dye-based polarizing plate has a problem in that the transmittance is low, that is, the contrast is low, as compared with the iodine-based polarizing plate having the same degree of polarization. However, a dye having various heat durability, high durability and high stability, And is characterized by high color selectivity by mixing.

However, conventionally, dyes dyeing paper-making materials and cellulose-based fibers with a solid blue color include C.I. Direct Blue 15, 200, 202, 203 and the like are known and widely used in the paper industry and the dyeing industry. However, as a drawback common to these dyes, a common problem when these dyes are used as raw materials is that the dianisidine used as the main raw material is a toxic chemical corresponding to the first class of the specific chemical, and the dye itself In the use of dianisidine, it is necessary to strictly observe the Industrial Safety and Health Law, and it is necessary to work under extremely strict protection facilities, Respectively.

On the other hand, examples of blue dyes other than dianisidine include C.I. Direct Blue 67, 78, 106, 108 and the like, but all of them have defects such as defective dyeability obviously compared with the dianisidine blue dye. That is, it is difficult to easily obtain a dyed dye having good durability and durability without the use of dianisidine. Therefore, dianisidine is a toxic chemical corresponding to the first kind of a specific chemical, and in order to avoid exposure to workers A large amount of blue dyes are used, which are expensive to protect the equipment, and are in use. Therefore, it has long been required to develop not only the dye industry, the paper industry but also the polarizing plate, to obtain a durable and dyeable blue dye without using a raw material corresponding to a specific chemical substance such as dianisidine. Particularly, in the development of a polarizing element, it has been proposed that it has a high polarization characteristic, and furthermore, it is very difficult to combine a polarization function, color and durability.

Further, in recent years, the intensity of a light source has increased as an optical use, and there has been a problem that a polarizing plate is discolored due to strong light thereof and accompanying heat, and the demand for improvement thereof is high.

Patent Document 1: Patent Publication No. 64-5623 Patent Document 2: Patent No. 2985408

Non-Patent Document 1: Dye chemistry; Hosoda Yutaka; Gibo Party

A dye having an excellent blue dye without using a raw material belonging to a specific chemical substance such as dianisidine is disclosed in Patent Document 1. Patent Document 2 discloses a polarizing plate that can be obtained by including the dye described in Patent Document 1 in a polyvinyl alcohol film and stretching it.

However, the dye used in Patent Document 1 or 2 has a problem that the purity of the dye is low, the amount of impurities is large, and the polarization characteristic is low, depending on the production method. Particularly, as the impurity, it is known that when the coloring matter represented by the chemical formula (1) is produced, copper is desorbed depending on the production conditions thereof and the chemical formula (2) is generated. And the purity of the dye is 90%, the demand for high polarization degree and high contrast in recent years is insufficient, and improvement has been demanded. It has been demanded to develop a polarizing element having a good blue dye and having good polarization characteristics without using a raw material belonging to a specific chemical substance such as dianisidine in this process.

Wherein A, R, and X have the same meanings as those in the formula (1).

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that a polarizing element comprising a polyvinyl alcohol resin or a derivative thereof and a film dyed three or more times by containing a dichroic dye and at least one of the dichroic dyes The azo compound represented by the formula (1) or a salt thereof and the content of the azo compound represented by the formula (2) or the salt thereof is 10% or less, whereby the dye is a dye having a solid blue dye having good dyeability, A polarizing element or a polarizing plate having polarization characteristics can be obtained.

That is,

(1) A polarizing element comprising a polyvinyl alcohol resin or a derivative thereof and a film having a dichroic dye and stretched three times or more, wherein at least one of the dichroic dyes is an azo compound represented by the formula (1) And the content of the azo compound represented by the formula (2) or a salt thereof in the polarizing element is 10% or less.

Wherein A, R, and X have the same meanings as those in the formula (1).

(2) A polarizing plate in which a protective layer is provided on one side or both sides of the polarizing element described in (1)

(3) The polarizing element described in (1), or the liquid crystal display using the polarizing plate described in (2)

(4) The polarizing element described in (1), or the lens using the polarizing plate described in (2)

(5) A polarizing element comprising a polyvinyl alcohol resin or a derivative thereof and a dichroic dye and stretched three times or more, wherein at least one of the dichroic dyes is an azo compound represented by the formula (1) And the ratio of the content of the azo compound or salt thereof represented by the formula (1) and the azo compound or its salt in the polarizing element represented by the formula (2) is 9: 1 to 10: 0 Manufacturing method ".

The polarizing element or the polarizing plate containing the polyvinyl alcohol resin or derivative thereof and the dichroic dye of the present invention can be made into a blue dye having good durability and good dyeability without using a raw material corresponding to a specific chemical substance such as dianisidine , And has good polarization characteristics.

Carrying out the invention Best form for

Hereinafter, the present invention will be described in detail.

The present invention relates to a polarizing element comprising a polyvinyl alcohol resin or a derivative thereof and a film having a dichroic dye and stretched three times or more, wherein at least one of the dichroic dyes is an azo compound represented by the formula (1) And the content of the azo compound represented by the general formula (2) or its salt is 10% or less. Therefore, it is possible to provide a polarizing element which does not use a raw material belonging to a specific chemical substance such as dianhydride, A coloring matter having a blue dye, and a characteristic having good polarization characteristics can be achieved.

Wherein A, R, and X have the same meanings as those in the formula (1).

The coloring matter represented by the formula (1) has a good polarizing property and may be contained in the film. On the other hand, the coloring matter represented by the formula (2) contains a large amount of the polarizing property in the film. Therefore, the purity (content) of the dye represented by the formula (2) or its salt is 10% or less, preferably 5% or less, more preferably 3% or less, and more preferably 1% or less desirable.

The purity of the dye in this case is a purity measured by an area ratio by high-performance liquid chromatography (hereinafter abbreviated as HPLC), and 0.5 g of a polyvinyl alcohol-based resin film containing a dichroic dye is dissolved in 50 wt% Of pyridine water for 24 hours, and after extraction with a dye, the peak area ratio measured by HPLC.

The dye represented by the formula (1) is dissolved in water, and when the solution is measured by HPLC, the purity of the dye represented by the formula (2) in the dye is preferably 10% or less in terms of area ratio. The dye represented by the formula (2) is an impurity produced in the production process of the formula (1) or the polarizing device production process, and the impurity mainly occurs when the copper contained in the formula deviates. Therefore, the content of the dye represented by the formula (2) is preferably small. In producing a polarizing element or a polarizing plate, it is preferably 90% or more, preferably 95% or more, and more preferably 98% or more, in terms of dye purity expressed by the formula (1). Therefore, the ratio of the compounds represented by the formulas (1) and (2) is preferably 9 to 1 to 10 to 0.

Specific examples of the dye represented by the formula (1) used in the present invention are listed below. The sulfo group, the carboxy group and the hydroxy group in the formula represent the free acid form.

The azo compound represented by the formula (1) or its salt can be easily produced by known diazotization and coupling according to the production method of an ordinary azo dye as described in Non-patent Document 1. [ As a concrete production method, a naphthalene ring having an amino group is diazotized by a known method, and then the compound represented by the formula (12) is coupled at 10 to 20 ° C and hydrolyzed as required to obtain the compound represented by the formula (13) To obtain the indicated amino azo compound.

In the formula, R represents the same meaning as in the formula (1).

Wherein A and R have the same meanings as those shown in the formula (1).

The aminoazo compound represented by the formula (13) is diazotized by a known method to obtain 6-phenylamino 1-naphthol-3-sulfonic acid having a hydrogen atom, a hydroxyl group, a carboxy group, a methyl group, J: acid) at 10 to 20 占 폚 to obtain the disazo compound represented by the formula (14).

Wherein A, R, and X have the same meanings as those in the formula (1).

Subsequently, copper sulfate, for example, ammonia water, aminoalcohol and hexamethylenetetramine are added and the copperation reaction is carried out at 85 to 95 ° C to obtain a solution containing the copper complex salt compound represented by the formula (1).

This solution is then evaporated to dryness or salting-out, followed by drying and pulverization to obtain a colorant represented by the formula (1) of the present invention. The compound represented by the formula (1) thus obtained is generally used as a sodium salt, but it can be used as a lithium salt, a potassium salt, an ammonium salt, an alkylamine salt and the like.

However, depending on the conditions of the production process or the polarizing element production process, the copper complex salt may be separated from copper to give a disazo compound represented by the formula (2). Factors causing the compound of the formula (2) are generated according to the temperature during evaporation and drying, the solution upon salting, the concentration of the solution, and the time thereof. The dye represented by the formula (2) may also be produced by a process such as a dyeing temperature, a dyeing time, a drying temperature after stretching, and a drying time, which will be described later. The present invention can be achieved by preventing the generation of the compound of the formula (2) from occurring in the dye production process and the polarizing element production process. The dye represented by the formula (2) has a transmittance in the case where two polarizing plates of a polarizing element having a low polarizing property and containing a dye represented by the formula (1) are superimposed so that the absorption axis direction is orthogonal, (2) are different from each other in terms of the transmittance when the polarizing plates of two polarizing elements containing the dye of formula (1) and formula (2) are superimposed so that the absorption axis directions are orthogonal, The color is not blue but reddish, so it becomes purple or a color close to that. In the case where a good polarizing element is obtained from the polarizing property and a blue polarizing plate is desired, the content of the dye of the formula (2) in the polarizing element is required to be 10% or less with respect to the dye of the formula (1). When the dye of formula (2) is contained in an amount of 10% or more, good polarization characteristics and desirable blue color can not be obtained. Therefore, the content of the dye represented by the formula (2) is preferably small.

The coloring matter represented by the formula (1) can be used in combination with other organic coloring matters to improve the color correction and the polarization performance. The organic dye to be used in this case is not particularly limited as long as it is a dye having an absorption property in a wavelength region in which the dye is different from the dye used in the present invention and has a high polarization property, Dyes such as azo dyes, anthraquinone dyes, quinophthalone dyes and the like, and the dyes described in the color index are also exemplified. For example, Mr. children. Direct, Yellow 12, Mr. children. Direct, Yellow 28, Mr. children. Direct, Yellow 44, Mr. children. Direct. Orange 26, Mr.. children. Direct. Orange 39, Mr. children. Direct. Orange 107, Mr.. children. Direct.Red 2, Mr.. children. Direct.Red 31, Mr. children. Direct.Red 79, Mr.. children. Direct.Red 81, Mr.. children. Direct.Red 247, Mr.. children. Direct.Green 80, Mr.. children. Direct, Green 59, and JP 2001-33627, JP 2002-296417, JP 2003-215338, WO2004 / 092282, JP 2001-0564112, JP 2001-027708, JP 11-218611, JP 11-218610, and JP 60 Organic dyes described in JP-A-156759, and the like. These organic dyes can be used as salts of alkali metal salts (for example, Na salts, K salts, Li salts), ammonium salts, or amines besides organic acids. However, the dichroic dye is not limited to these, and a known dichroic compound can be used, but azo dyes are preferable. In addition to the dichroic dyes shown in these examples, other organic dyes may be used in combination if necessary.

The types of organic dyes to be blended differ depending on whether the target polarizing element is a neutral polarizing element, a color polarizing element for a liquid crystal projector, or a color polarizing element of a salt thereof. The compounding ratio is not particularly limited, and the compounding amount can be arbitrarily set according to requirements such as light source, durability, desired color, and the like.

It is a feature of the present invention that the dye represented by the formula (1) is impregnated in a polyvinyl alcohol-based resin film. The production method of the polyvinyl alcohol-based resin constituting the polarizing element is not particularly limited and can be produced by a known method. The polyvinyl alcohol resin can be produced, for example, by saponifying a polyvinyl acetate resin. Examples of the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers and unsaturated sulfonic acids. The degree of saponification of the polyvinyl alcohol-based resin is preferably 85 to 100 mol%, more preferably 95 mol% or more. The polyvinyl alcohol-based resin may also be modified. For example, polyvinyl formal or polyvinyl acetal modified with aldehyde may be used. The degree of polymerization of the polyvinyl alcohol-based resin is usually preferably from 1,000 to 10,000, more preferably from 1,500 to 6,000.

Such a polyvinyl alcohol-based resin film is used as the original film. The method of forming the polyvinyl alcohol-based resin is not particularly limited, and a film can be formed by a known method. In this case, the polyvinyl alcohol based resin film may contain glycerin, ethylene glycol, propylene glycol, or a low molecular weight polyethylene glycol as a plasticizer. The amount of the plasticizer is preferably 5 to 20% by weight, more preferably 8 to 15% by weight. The thickness of the original film made of a polyvinyl alcohol-based resin is not particularly limited, but is preferably 5 to 150 탆, more preferably 10 to 100 탆.

In the polyvinyl alcohol-based resin film, a swelling step is first performed. The swelling process is performed by immersing the polyvinyl alcohol resin film in a solution at 20 to 50 캜 for 30 seconds to 10 minutes. The solution is preferably water. In the case where the time for producing the polarizing element is shortened, the swelling step can be omitted since the swelling occurs even in the dyeing treatment of the dye.

After the swelling process, a dyeing process is carried out. In the dyeing step, impregnation is carried out by immersing the polyvinyl alcohol-based resin film in a solution containing a dichroic dye. The solution temperature in this step is preferably 5 to 60 占 폚, more preferably 20 to 50 占 폚, and particularly preferably 35 to 50 占 폚. The time for immersion in the solution can be suitably adjusted, but it is preferably adjusted to 30 seconds to 20 minutes, more preferably 1 to 10 minutes. The dyeing method is preferably carried out by immersing in the above solution, but it can be carried out by applying the solution to the polyvinyl alcohol-based resin film.

The solution containing the dichroic dye may contain sodium chloride, sodium sulfate, anhydrous sodium sulfate, sodium tripolyphosphate and the like as a dyeing aid. The content thereof can be adjusted at an arbitrary concentration depending on the time and temperature depending on the dyeability of the dye, but the content is preferably 0 to 5% by weight, more preferably 0.1 to 2% by weight.

As the method of impregnating the dye, it may be carried out by immersing it in a solution containing a dichroic dye, but it may also be a method of containing a dye in the step of molding the disc of the polyvinyl alcohol resin film.

After the dyeing step, a cleaning step (hereinafter referred to as a cleaning step 1) can be performed before entering the next step. The cleaning step 1 is a step of cleaning the dye solvent attached to the surface of the polyvinyl alcohol based resin film in the dyeing step. By performing the cleaning step 1, migration of the dye into the liquid to be treated next can be suppressed. In the cleaning step 1, water is generally used. The cleaning method is preferable to be immersed in the above solution, but the solution can be cleaned by applying it to the polyvinyl alcohol based resin film. The cleaning time is not particularly limited, but is preferably 1 to 300 seconds, and more preferably 1 to 60 seconds. It is necessary that the temperature of the solvent in the cleaning step 1 is a temperature at which the hydrophilic polymer does not dissolve. In general, it is cleaned at 5 to 40 ° C.

After the dyeing step or the washing step 1, a step of containing a crosslinking agent and / or a water-proofing agent can be carried out. Examples of the crosslinking agent include boron compounds such as boric acid, borax or ammonium borate, polyvalent aldehydes such as glyoxal or glutaraldehyde, polyvalent isocyanate compounds such as biuret type, isocyanurate type or block type, titanium oxysulfate Based compound, and the like, but also ethylene glycol glycidyl ether, polyamide epichlorohydrin and the like can be used. Examples of the water-proofing agent include peroxydisuccinic acid, ammonium persulfate, calcium perchlorate, benzoin ethyl ether, ethylene glycol diglycidyl ether, glycerin diglycidyl ether, ammonium chloride, magnesium chloride and the like. Is used. A step of containing a crosslinking agent and / or a water-proofing agent is carried out by using at least one crosslinking agent and / or a water-repellent agent as shown above. As the solvent at this time, water is preferable but not limited. The concentration of the crosslinking agent and / or the water-proofing agent in the solvent in the step of containing the crosslinking agent and / or the water-proofing agent is preferably 0.1 to 6.0% by weight, more preferably 1.0 to 4.0% by weight desirable. The solvent temperature in this step is preferably 5 to 70 캜, more preferably 5 to 50 캜. The method of containing the crosslinking agent and / or the water-proofing agent in the polyvinyl alcohol-based resin film is preferably carried out in the above solution, but the solution may be applied or coated on the polyvinyl alcohol-based resin film. The treatment time in this step is preferably 30 seconds to 6 minutes, more preferably 1 to 5 minutes. However, it is not essential to contain a cross-linking agent and / or a water-proofing agent, and in the case where it is desired to shorten the time, this cross-linking treatment or waterproofing treatment may be omitted.

After the dyeing step, the washing step 1, or the step of containing a crosslinking agent and / or a water-proofing agent is carried out, a drawing step is carried out. The stretching step is a step of uniaxially stretching the polyvinyl alcohol-based film. The stretching method may be either a wet stretching method or a dry stretching method, and the present invention can be achieved because the stretching magnification is 3 times or more. The stretching ratio is preferably 3 times or more, and preferably 5 to 7 times.

In the case of the dry stretching method, when the stretching heating medium is an air medium, the temperature of the air medium is preferably stretched at a room temperature to 180 ° C. The humidity is preferably treated in an atmosphere of 20 to 95% RH. Examples of the heating method include a roll-to-bed stretching method, a roll heating stretching method, a rolling stretching method, and an infrared heating stretching method, but the stretching method thereof is not limited. The stretching process can be performed in one stage, but it can also be performed in two or more stages in multi-stage stretching.

In the case of the wet stretching method, stretching is performed in water, a water-soluble organic solvent, or a mixed solution thereof. It is preferable to carry out the stretching treatment while immersing it in a solution containing a crosslinking agent and / or a water-proofing agent. Examples of the crosslinking agent include boron compounds such as boric acid, borax or ammonium borate, polyvalent aldehydes such as glyoxal or glutaraldehyde, polyvalent isocyanate compounds such as biuret type, isocyanurate type or block type, titanium oxysulfate Based compound, and the like, but also ethylene glycol glycidyl ether, polyamide epichlorohydrin and the like can be used. Examples of the water-proofing agent include peroxy succinic acid, ammonium persulfate, calcium perchlorate, benzoin ethyl ether, ethylene glycol diglycidyl ether, glycerin diglycidyl ether, ammonium chloride, magnesium chloride and the like. The stretching is carried out in a solution containing at least one crosslinking agent and / or a water-repellent agent as shown above. The crosslinking agent is preferably boric acid. The concentration of the crosslinking agent and / or the water-proofing agent in the stretching step is preferably 0.5 to 15% by weight, more preferably 2.0 to 8.0% by weight. The draw ratio is preferably 2 to 8 times, more preferably 5 to 7 times. The stretching temperature is preferably 40 to 60 占 폚, more preferably 45 to 58 占 폚. The stretching time is usually 30 seconds to 20 minutes, more preferably 2 to 5 minutes. The wet stretching process can be performed in one stage, but it can also be performed in two or more stages in multi-stage stretching.

After the stretching process, there may be a step of depositing a crosslinking agent and / or a water-resisting agent on the surface of the film, or a foreign matter may adhere to the film surface. Therefore, a cleaning step (hereinafter referred to as a cleaning step 2) for cleaning the film surface can be performed. The cleaning time is preferably 1 second to 5 minutes. Although it is preferable to immerse the cleaning solution in the cleaning solution, the solution can be cleaned by coating or coating on the polyvinyl alcohol-based resin film. The cleaning treatment may be performed in one stage, or the treatment may be performed in two or more stages. The solution temperature in the washing step is not particularly limited, but is usually 5 to 50 占 폚, preferably 10 to 40 占 폚.

Examples of the solvent to be used in the above treatment step include water, dimethylsulfoxide, N-methylpyrrolidone, methanol, ethanol, propanol, isopropyl alcohol, glycerin, ethylene glycol, propylene glycol, diethylene glycol, triethylene But are not limited to, alcohols such as glycol, tetraethylene glycol or trimethylolpropane, and amines such as ethylenediamine or diethylenetriamine. Mixtures of one or more of these solvents may also be used. The most preferred solvent is water.

After the stretching process or the cleaning process 2, the drying process of the film is performed. The drying process can be carried out by natural drying. However, in order to further improve the drying efficiency, moisture can be removed from the surface by a roll compression, an air knife, or an absorbing roll, and / or air drying can be performed. The drying treatment temperature is preferably a drying treatment at 20 to 100 占 폚, more preferably a drying treatment at 60 to 100 占 폚. The drying treatment time is 30 seconds to 20 minutes, preferably 5 to 10 minutes.

In this way, the polyvinyl alcohol-based resin film polarizing element of the present invention having improved durability can be obtained. Even if the film for adsorbing the dichroic dye in the polarizing element is not a polyvinyl alcohol-based resin, even if it is a film obtained from an amylose-based resin, a starch-based resin, a cellulose-based resin or a polyacrylate-based resin, , Stretching, shear orientation, etc., the same polarizing element can be produced, but a polarizing element film made of a polyvinyl alcohol-based resin film is most suitable.

The obtained polarizing element is provided with a transparent protective layer on one side or both sides thereof to form a polarizing plate. The transparent protective layer can be designed as a coating layer of a polymer or as a laminate layer of a film. As the transparent polymer or film forming the transparent protective layer, a transparent polymer or film having high mechanical strength and good thermal stability is preferable. As the material used as the transparent protective layer, for example, a cellulose acetate resin or a film thereof such as triacetylcellulose or diacetylcellulose, an acrylic resin or a film thereof, a polyvinyl chloride resin or a film thereof, a nylon resin or a film thereof, Or a film thereof, a polyarylate resin or a film thereof, a cyclic polyolefin resin or a film thereof using a cyclic olefin such as norbornene as a monomer, a polyethylene, a polypropylene, a polyolefin having a cyclo or norbornene skeleton or a copolymer thereof, A resin or a polymer of imide and / or amide in the main chain or side chain, or a film thereof. As the transparent protective layer, a resin having liquid crystallinity or a film thereof can be provided. The thickness of the protective film is, for example, about 0.5 to 200 mu m. A polarizing plate is produced by providing one or more layers of the same type or different kinds of resins or films on one side or both sides thereof.

In order to bond the transparent protective layer to the polarizing element, an adhesive is required. The adhesive is not particularly limited, but a polyvinyl alcohol-based adhesive is preferable. Examples of the polyvinyl alcohol-based adhesive include, but are not limited to, Goseonol NH-26 (manufactured by Nihon Goseisha Co., Ltd.), Eceval RS-2117 (manufactured by Kuraray Co., Ltd.) and the like. To the adhesive, a cross-linking agent and / or a water-proofing agent may be added. A maleic anhydride-isobutylene copolymer is used as the polyvinyl alcohol-based adhesive, but an adhesive obtained by mixing a crosslinking agent as needed can be used. Examples of the maleic anhydride-isobutylene copolymer include isobarane # 18 (Kuraray Co., Ltd.), Isoban # 04 (Kuraray Co., Ltd.), ammonia-modified isobarane # 104 (Kuraray Co., (Manufactured by Kuraray Co., Ltd.), imidized isoban # 304 (manufactured by Kuraray Co., Ltd.) and imidized isoban # 310 (manufactured by Kuraray Co., Ltd.). A water-soluble polyfunctional epoxy compound may be used as the crosslinking agent. Examples of the water-soluble polyvalent epoxy compound include Denacol EX-521 (manufactured by Nagase Chemtech Co., Ltd.) and Tetrath-C (manufactured by Mitsui Gas Chemical). As an adhesive other than the polyvinyl alcohol-based resin, a known adhesive such as urethane-based, acrylic-based, or epoxy-based adhesive may be used. In addition, additives such as a zinc compound, a chloride, and an iodide can be contained at a concentration of about 0.1 to 10 wt% at the same time for the purpose of improving the adhesive force of the adhesive or improving the water resistance. The additives are not limited either. The transparent protective layer is bonded with an adhesive, and then dried or heat-treated at a suitable temperature to obtain a polarizing plate.

The polarizing plate thus obtained may be bonded to a display device such as liquid crystal, organic electroluminescence or the like depending on the case, and various functional layers for improving the viewing angle and / or improving the contrast on the surface of the protective layer or film, A layer or a film having brightness enhancement can be provided. It is preferable to use a pressure-sensitive adhesive in order to bond the polarizing plate to these films or display devices.

The polarizing plate may have various known functional layers such as an antireflection layer, an antiglare layer (hardening layer), and a hard coat layer on the other surface, that is, the exposed surface of the protective layer or film. A coating method is preferable for producing the layer having various functions, but a film having the function can be bonded through an adhesive or a pressure-sensitive adhesive. It is also possible to use a layer or a film for controlling the phase difference called various functional layers.

In the above method, it is possible to obtain a polarizing element and a polarizing plate having a dye having excellent blue dye, good polarizing properties and high durability without using a raw material corresponding to a specific chemical substance such as the dianisidine of the present invention have. The display using the polarizing element or the polarizing plate of the present invention has a high reliability, a high contrast for a long term, and a display with high color reproducibility.

The polarizing element or polarizing plate of the present invention thus obtained can be used as a polarizing plate by attaching a protective film to provide a protective layer, a functional layer, a support or the like as required and to provide a liquid crystal projector, an electronic calculator, a clock, a notebook computer, a word processor, Lenses, polarizing glasses, car navigation systems, indoor and outdoor meters, and indicators.

Example

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto. The evaluation of the degree of polarization shown in the examples was carried out as follows.

When two polarizing plates obtained by bonding a protective film to both surfaces of a polarizing element film are superimposed on each other so that their absorption axis directions are the same, the transmissivity is the flat actuation transmittance Tp and the two polarizing plates are superimposed such that their absorption axes are orthogonal Was determined as the orthogonally polarized transmittance Tc.

The polarization degree Py is obtained from the equilibrium transmittance Tp and the orthogonality transmittance Tc by the following equation (i).

Each transmittance was measured using a spectrophotometer ("U-4100" manufactured by Hitachi, Ltd.).

32.5 parts of 2-aminonaphthalene-4,8-disulfonic acid (available under the trade name of C acid) was dissolved in 145 parts of water, and the mixture was added to 140 parts of water containing 26 parts of 35% hydrochloric acid, 6.9 parts of sodium nitrite was added at 15 to 20 ° C, Lt; / RTI > Subsequently, an aqueous solution containing 13.7 parts of 2-methoxyaminobenzene and 17.5 parts of 35% hydrochloric acid was added and the mixture was coupled at 20 占 폚 for 4 hours while maintaining the pH at 3.0 to 3.5 with sodium acetate. Subsequently, 21.4 parts of 35% hydrochloric acid was added to the amino azo compound, 6.9 parts of sodium nitrite was added at 10 ° C, and the second diazotization was performed at 15 to 20 ° C for 3 hours. This was then added to an aqueous solution of 31.5 parts of phenyl J acid, 125 parts of water and 11 parts of soda ash while maintaining pH 8.5 to 9.5 while injecting the soda ash solution. The secondary coupling was carried out until no confirmation was obtained to obtain a disazo compound. Subsequently, copper complex salt prepared by adding 30.5 parts of monoethanolamine to 25 parts of copper sulfate was added. The copper complex was reacted at 95 ° C for 10 hours until no unreacted material was identified on the thin layer chromatography. By weight was prepared.

Example One

&Lt; Production of polarizing element &

A polyvinyl alcohol resin film (VF series, manufactured by Kuraray Co., Ltd.) having a degree of saponification of 99% or more and having a thickness of 75 탆 was dipped in hot water at 40 캜 for 2 minutes to swell. The swollen film was treated with 0.05% by weight of a colorant powder (HPLC purity: 98.2%) which was salted with a 25% by weight of a Sanuki salt in a 20% by weight aqueous solution containing a dye represented by the formula (3) , And 0.1% by weight of sodium tripolyphosphate was immersed in an aqueous solution at 45 캜 to carry out dye adsorption. The dye-adsorbed film was washed with water, washed, and then subjected to boric acid treatment for 1 minute in an aqueous solution containing 2% by weight of boric acid at 40 캜. The film obtained by the boric acid treatment was subjected to a treatment for 5 minutes in an aqueous solution at 55 캜 containing 3.0% by weight of boric acid while being stretched 5.0 times. The film obtained by the boric acid treatment was cleaned with water at 30 캜 for 15 seconds while maintaining the tension of the film. The film obtained by the treatment was immediately dried at 70 캜 for 9 minutes to obtain a polarizing element having a film thickness of 28 탆.

The obtained polarizing element was dissolved and subjected to HPLC measurement. The purity of the dye represented by the formula (3) in the film was 98.1%.

A triacetylcellulose film (TD-80U, manufactured by Fuji Photo Film Co., Ltd., hereinafter abbreviated as TAC) having an alkali treatment of the obtained polarizing element was laminated with a polarizing element / adhesive layer / TAC using a polyvinyl alcohol- And laminated to obtain a polarizing plate. The obtained polarizing plate was cut into 40 mm x 40 mm and bonded to a 1 mm transparent glass plate through a pressure-sensitive adhesive PTR-3000 (manufactured by Nippon Kayaku Co., Ltd.) in a constitution of TAC / adhesive layer / polarizing element / adhesive layer / TAC / adhesive layer / transparent glass plate, Respectively.

Example 2

A coloring matter solution having a compound represented by the formula (4) was prepared by replacing 2-methoxyaminobenzene with 2,5-dimethoxyaminobenzene to prepare a coloring matter powder (HPLC purity: 98.6%), Except that the polarizing element was obtained in the same manner as in Example 1, When the polarizing element obtained in Example 2 was dissolved and subjected to HPLC measurement, the purity of the dye represented by the formula (4) in the film was 98.8%.

Example 3

Except that the dye solution having the compound represented by the formula (5) was prepared by replacing the phenyl J acid used in Example 1 with methylphenyl J acid to obtain a polarizing element by the dye powder (HPLC purity: 97.8%) In the same manner, a polarizing plate and evaluation samples were prepared. When the polarizing element obtained in Example 3 was dissolved and subjected to HPLC measurement, the purity of the dye represented by the formula (4) in the film was 97.2%.

Comparative Example One

A dye powder (HPLC purity: 88.9%) was prepared by salting out a 20 wt% aqueous solution containing the dye represented by the formula (3) used in Example 1 with 25 wt% of a Sanuki salt, ) Was used as the polarizing element. The dried coloring matter powder contained 7.7% of a dye represented by the chemical formula (15). The obtained polarizing element was dissolved and subjected to HPLC measurement. The coloring matter represented by the formula (3) in the film contained 86.2% by HPLC measurement and contained 12.1% of the dye represented by the formula (15).

Comparative Example 2

(HPLC purity: 85.1%) obtained by salting out a 20 wt% aqueous solution of the formula (4) used in Example 2 with 25 wt% of a Sanuki salt and drying at 90 ° C Manufactured the same polarizing element. The dried coloring matter powder contained 8.3% of a dye represented by the formula (16). Further, when the obtained polarizing element was dissolved and subjected to HPLC measurement, the coloring matter represented by the formula (4) in the film contained 84.5% by HPLC measurement and contained 13.9% of the dye represented by the formula (16).

Comparative Example 3

Using a dye powder (HPLC purity 87.9%) obtained by salting out a 20 wt% aqueous solution represented by the formula (5) used in Example 3 with 25 wt% of a Sanuki salt and drying at 90 ° C, Manufactured the same polarizing element. The dried coloring matter powder contained 9.1% of the dye represented by the chemical formula (17). The obtained polarizing element was dissolved and subjected to HPLC measurement. The coloring matter represented by the formula (5) in the film contained 88.1% by HPLC measurement and contained 10.3% of the dye represented by the formula (17).

Table 1 shows the wavelengths with the maximum degree of polarization of the evaluation samples obtained in Examples 1 to 3 and Comparative Examples 1 to 3 and the values of the light transmittance, the transmittance, the transmittance and the transmittance, which are obtained by dividing the parallel transmittance, the orthogonal transmittance, . &Lt; / RTI >

As is apparent from Table 1, the polarizing plate of the present invention exhibits a high degree of polarization and a high contrast, whereas in Comparative Example, the degree of polarization is low, which is about 0.3 to 0.8% lower and the contrast is lowered by about 3% Able to know. From this point of view, the polarizing plate of the present invention has a high polarization rate and is used for a liquid crystal projector, an electronic calculator, a clock, a notebook computer, a word processor, a liquid crystal television, a polarizing lens, polarizing glasses, car navigation, It is possible to obtain a liquid crystal display device and a lens having high contrast without using a dye belonging to a specific chemical substance such as dianisidine.

Example 4

The polarizing plate obtained in the same manner as in Example 2 was put in an environment of 105 ° C for 401 hours to confirm a change of the orthogonal transmittance and hue of the polarizing plate. A * and b * of orthogonal colors can be expressed by the color system displayed by JIS Z8729 (color display method L *, a *, b * indicator and L *, u *, v * Respectively. The term orthogonal color as used herein means that the two polarizing plates are measured in a state in which they are superimposed so that the absorption axes thereof are orthogonal to each other. In the L *, a *, and b * colorimetric systems, the closer the colors a * and b * are to zero, the more colors are represented by neural colors.

Comparative Example 4

The polarizing plate having an orthorhombic transmittance of 0.052% of the wavelength having the maximum degree of polarization of the evaluation sample obtained in the same manner as in Comparative Example 2 was put in an environment of 105 ° C for 401 hours to confirm a change of the orthogonal transmittance and hue of the polarizing plate. A * and b * of orthogonal colors were measured with a colorimetric system represented by JIS Z8729 (color display method L *, a *, b * display system and L *, u *, v * .

Comparative Example 5

Except that the dye used in Example 4 was changed to the dye shown in Example 1 of Patent Publication No. 64-5623 and a polarizing plate having an orthogonal transmittance of 0.050% of the wavelength having the maximum degree of polarization of the evaluation sample was obtained, And the polarizer was subjected to 401 hours of injection to confirm the change of the orthogonal transmittance and hue of the polarizing plate. About a color The a * and b * of orthogonal colors were measured by a color system displayed by JIS Z8729 (color display method L *, a *, b * display system and L *, u *, v * color system).

The initial values of the orthogonal transmittances of the wavelengths having the maximum polarization degrees of the evaluation samples obtained in Example 4, Comparative Example 4 and Comparative Example 5, the values after the heat resistance test, the initial values of a * and b * , And a rising average value (hereinafter, abbreviated as a GM value) with respect to a change in a * and b *.

As is clear from Table 2, the polarizing plate of the present invention is superior in heat resistance to the polarizing plate in that the change in the orthogonal transmittance and the color change are superior to those in the comparative example. In addition, it had higher heat resistance than Comparative Example 5 in which R of the formula (1) was a methyl group.

Example 5

The polarizing plate obtained in the same manner as in Example 2 was put in an environment at 85 캜 and 85% humidity for 401 hours to confirm the polarizing plate's quadrature transmittance and color change. A * and b * of orthogonal colors are measured by the color system displayed by JIS Z8729 (color display method L *, a *, b * display system and L *, u *, v * Respectively. The term orthogonal color as used herein means that two polarizing plates are measured in a state in which they are superposed so that their absorption axes are orthogonal to each other. In the L *, a *, and b * colorimetric systems, the closer the colors a * and b * are to zero, the more colors are represented by neural colors.

Comparative Example 6

A polarizing plate having an orthogonal transmittance of 0.059% at a wavelength having the maximum degree of polarization of the evaluation sample obtained in the same manner as in Comparative Example 2 was put in an environment at 85 캜 and 85% humidity for 401 hours to confirm a change in the orthogonal transmittance and hue of the polarizing plate . A * and b * of orthogonal colors are measured by the color system displayed by JIS Z8729 (color display method L *, a *, b * display system and L *, u *, v * Respectively.

Comparative Example 7

The dye used in Example 4 was changed to the dye represented by Example 1 of Patent Publication No. 64-5623 and a polarizing plate having an orthogonal transmittance of 0.053% of the wavelength having the maximum degree of polarization of the evaluation sample was obtained. 85% environment for 401 hours, and the change of color and orthogonal transmittance of the polarizing plate was confirmed. About a color The a * and b * of orthogonal colors were measured by a color system displayed by JIS Z8729 (color display method L *, a *, b * display system and L *, u *, v * color system).

The initial values of the orthogonal transmittances of the wavelengths having the maximum polarization degrees of the evaluation samples obtained in Example 5, Comparative Examples 6 and 7, the values after the anti-moisture heat test, the initial values of a * and b * Value, and a rising average value (hereinafter, abbreviated as GM value) with respect to a change of a * and b *.

As is evident from Table 3, the polarizing plate of the present invention is superior in heat resistance to the polarizing plate in that the change in the orthogonal transmittance and the color change are superior to those in the comparative example. In addition, the transmittance change was smaller than that of Comparative Example 7 in which R of the formula (1) was a methyl group, and thus it had high humidity resistance. From this point of view, the polarizing plate of the present invention has a high polarization rate and is used for a liquid crystal projector, an electronic calculator, a clock, a notebook computer, a word processor, a liquid crystal television, a polarizing lens, polarizing glasses, automobile navigation, , Liquid crystal display devices having high durability, lenses and the like can be obtained without using pigments belonging to specific chemical substances such as dianhydrides and dianisidine.

Claims

A method of producing a polarizing element comprising a film containing a polyvinyl alcohol resin or a derivative thereof and a dichroic dye and stretched three times or more,
The method comprises:
A step of dying a polyvinyl alcohol based resin film by immersing the film in an aqueous solution containing the dichroic dye at a temperature of 5 to 60 DEG C,
A step of uniaxially stretching the polyvinyl alcohol-based resin film at 40 to 60 캜 while immersing the polyvinyl alcohol-based resin film in an aqueous solution containing a crosslinking agent and / or a water-proofing agent, and
And drying the wetted polyvinyl alcohol-based resin film at 20 to 70 占 폚,
The dichroic dye includes an azo compound represented by the formula (1) or a salt thereof, and an azo compound represented by the formula (2) or a salt thereof,
The ratio of the content of the azo compound represented by the formula (1) or its salt in the polarizing element to the azo compound or its salt represented by the formula (2) in the range of 9: 1 to 10: 0 (not including 10: 0) ego,
0.5 g of the above-mentioned film containing the dichroic dye was immersed in 50% by weight of pyridine water for 24 hours to extract the dye, and then the ratio expressed by the peak area ratio measured by high performance liquid chromatography Wherein the polarizing element is a polarizing element.

Wherein A, R, and X have the same meanings as those in the formula (1).

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