KR20070116309A - Adhesive and polarizing plate - Google Patents

Abstract

An adhesive, and a polarizer prepared by using the adhesive are provided to improve the adhesive strength between a polarizer and a protection film and to reduce the shrinkage remarkably. An adhesive comprises a high polymerization aqueous resin; a lower polymerization aqueous resin; a dialdehyde compound; and optionally a metal salt, wherein the difference of average degree of polymerization between the high polymerization aqueous resin and a lower polymerization aqueous resin is 300-3,000. Preferably the aqueous resin is a poly(vinyl alcohol)-based resin; and the dialdehyde compound is at least one selected from glyoxal, terephthalaldehyde and glutaraldehyde; and the metal salt is zinc chloride.

Description

Adhesive and Polarizing Plate

The present invention relates to an adhesive and a polarizing plate.

The polarizing plate usually laminates a cellulose protective film represented by a transparent resin film, for example triacetyl cellulose, on one or both sides of a polarizing film containing a polyvinyl alcohol-based resin in which a dichroic dye is adsorbed and oriented. It becomes one structure, It bonds to a liquid crystal cell with an adhesive via another optical film as needed, and makes it a component part of a liquid crystal display device.

As the liquid crystal display device is used in a wide variety of environments as its use expands, high environmental resistance is required for components constituting the liquid crystal display device. For example, in the liquid crystal display device of the mobile use represented by a mobile telephone, it is desired that it can also be used under wet heat, and high moisture heat resistance is also required also about the polarizing plate used there.

However, in the polarizing plate of the conventional structure, when it is exposed especially in a humid heat environment for a long time, polarization performance will fall easily and there existed a problem that the interface of a polarizing film and a cellulose acetate type film peels easily.

It is proposed to use thermoplastic cycloolefin resin as a protective film of a polarizing plate about such a problem. For example, it has been proposed to laminate a thermoplastic saturated norbornene-based resin sheet on at least one surface of a polyvinyl alcohol-based sheet through an acrylic pressure-sensitive adhesive and heat-press it to make a polarizing plate.

In addition, it has been proposed to laminate a protective film containing a thermoplastic saturated norbornene-based resin on at least one side of a polyvinyl alcohol polarizing film to form a polarizing plate, and as a result, an adhesive used is a polyurethane resin solution and a polyisocyanate resin solution. Dry adhesives, styrene butadiene rubber-based adhesives, epoxy-based two-component curable adhesives and the like have been proposed.

In addition, it has been proposed to make a polarizing plate by laminating a protective film containing a cyclic olefin resin on at least one surface of the polyvinyl alcohol polarizing film through an adhesive layer which is a mixture of a polyvinyl alcohol adhesive and a two-liquid type adhesive.

Moreover, it was proposed to make a polarizing plate by adhering the protective film containing a polyvinyl alcohol-type polarizing film and thermoplastic saturated norbornene-type resin with a polyurethane adhesive.

In addition, a polarizing plate in which a conventional triacetyl cellulose or the like is used as a protective film and the protective film and the polyvinyl alcohol polarizing film are laminated through an adhesive comprising a polyester polyol and an aliphatic polyisocyanate has been proposed.

However, in adhesives (also called pressure-sensitive adhesives) such as acrylics, the thickness of the adhesive itself is considerably thick, such as 10 to 50 µm, which is not suitable.

Dry lamination adhesives, styrene butadiene rubber adhesives, epoxy two-component curable adhesives, and the like contain organic solvents, and there are environmental and worker health problems. In addition, if the adhesive containing such an organic solvent is to be applied to a polarizing plate manufacturing equipment that does not use a conventional organic solvent, there is a problem that complicated modification of equipment such as the establishment of an explosion-proof equipment.

In addition, even if adhesives such as polyvinyl alcohol, urethane, acryl, vinyl acetate, and the like are generally known, sufficient adhesive strength and physical properties are difficult to be satisfied, and improvement is required.

The present invention is to solve the above problems,

It is an object of the present invention to provide an adhesive which can be used without using an organic solvent and which is excellent in adhesive strength and which can be usefully used for the production of a polarizing plate.

In addition, an object of the present invention is to provide a polarizing plate having excellent adhesion between a polarizing film and a protective film and having good physical properties.

The present inventors earnestly researched on the basis of the above-mentioned object, and as a result, in laminating a protective film made of a polarizing film, especially a polyvinyl alcohol-based polarizing film, in particular a protective film made of a cyclooleicin-based resin, a specific component is blended as an adhesive. By using this mixture, it discovered that the polarizing plate excellent in the adhesiveness of a polarizing film and a protective film was obtained, and reached this invention.

That is, the present invention comprises a high polymerization water resin, a low polymerization water resin, a dialdehyde compound, and the difference in the average degree of polymerization of the high polymerization water resin and the low polymerization water resin is characterized in that the 300 to 3000 range Provide adhesive.

In addition, the adhesive provides a metal salt further comprising.

In addition, the water-based resin provides an adhesive, characterized in that the polyvinyl alcohol (PVA) system.

In addition, the average degree of polymerization of the high-polymerization aqueous resin is in the range of 1500 to 3500, the average degree of polymerization of the low-polymerization aqueous resin provides an adhesive, characterized in that in the range of 100 to 1500.

In addition, the dialdehyde compound provides an adhesive, characterized in that at least one selected from glyoxal, terephthalaldehyde, and glutaraldehyde.

In addition, the metal salt provides an adhesive, characterized in that zinc chloride.

The present invention also provides a polarizing plate, in which the protective film is attached to at least one surface of the polarizing film with an adhesive, wherein the adhesive is used on at least one surface.

In addition, the polarizing film provides a polarizing plate, characterized in that the polyvinyl alcohol-based.

In addition, the protective film provides a polarizing plate, characterized in that at least one selected from cellulose-based and cycloolefin-based.

In addition, at least one of the polarizing film and the protective film provides a polarizing plate, characterized in that washed with an aqueous surfactant solution before bonding.

In addition, at least one of the polarizing film and the protective film is a polarizing plate characterized in that the surface treatment by at least one method of plasma treatment, corona treatment, ultraviolet irradiation treatment, flame (flame) treatment, and saponification treatment before bonding. to provide.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

Adhesive according to an embodiment of the present invention, a high polymerization water resin, a low polymerization water resin, including a dialdehyde compound, the difference in the average degree of polymerization of the high polymerization water resin and low polymerization water resin ranges from 300 to 3000 It is characterized by being mine.

The adhesive according to the invention is characterized in that it comprises two resins with different degrees of polymerization. The high polymerization and low polymerization water-based resins may be the same kind of resins having different degrees of polymerization, or different kinds of resins. The high polymerization and the low polymerization in the present invention are not distinguished with an absolute value of the degree of polymerization, but relatively distinguish two resins having different degrees of polymerization. By using a high polymerization resin and a low polymerization resin in this way, it is possible to increase the adhesive strength and to obtain physical properties (viscosities, etc.) that can easily perform the bonding operation, and to prevent the deterioration of the properties after the adhesion. do. The difference in the average degree of polymerization of the high-polymerization aqueous resin and the low-polymerization aqueous resin is preferably in the range of 300 to 3000, particularly in the range of 500 to 1500.

The high polymerization resin is not limited, but a resin having an average degree of polymerization in the range of 1500 to 3500 is preferable, and the low polymerization resin is preferably a resin having an average degree of polymerization in the range of 100 to 1500. Although the mixing ratio of the said high polymerization resin and the low polymerization resin is not specifically limited, The low polymerization resin is preferable in the range of 10-90 weight weight with respect to 100 weight of whole resin, and especially in the range of 30-70 weight. When the mixing ratio is less than the above range, the adhesive strength with the appropriate protective film is not sufficient, and when the mixing ratio is more than the above range, the viscosity of the adhesive rises, which is not preferable because the workability is degraded or the adhesive is broken.

In particular, in the case of a polarizing plate obtained after drying, the shrinkage phenomenon of the stretched polarizing film, in particular polyvinyl alcohol-based polarizing film appears. If the adhesive strength is not sufficient, the shrinkage ratio of the polarizing film before and after drying increases, which is caused by an increase in the shrinkage stress. Due to the disadvantage that the produced polarizing plate is bent or the peeling with the protective film is promoted, the present invention solved this method as described above.

In addition, the present invention is characterized by using an aqueous resin that can be usefully used in addition to the organic solvent. All water-based resins used in the adhesives known in the art are included in the present invention, and preferably polyvinyl alcohols such as fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, polyvinylbutylol, and partially acetalized polyvinyl alcohol. Aqueous resin is good. Moreover, you may contain functional groups, such as a carboxyl group or a carboxyl group derivative ester, an amine group, a silyl group, and a methylol group, as a copolymerization component. The high polymerization aqueous resin and the low polymerization aqueous resin may be the same kind or different kinds.

In addition, the adhesive according to the invention is characterized in that it comprises a dialdehyde compound. The dialdehyde compound is not limited but may be selected from at least one of glyoxal, terephthalaldehyde and glutalaldehyde, with glyoxal being particularly preferred. The dialdehyde compound is effective to include 1 to 65 weight, preferably 2 to 50 weight relative to 100 weight of the high-polymerization and low-polymerization aqueous resin. When the dialdehyde compound is less than the above range, the effect of preventing peeling of the protective film is less, and when the dialdehyde compound is more than the above range, the phenomenon that the adhesive is broken is not preferable.

In addition, the adhesive according to an embodiment of the present invention may further include a metal salt. Curing may be further promoted by adding the metal salt. Although not limited to the metal salt, zinc chloride, cobalt chloride, magnesium chloride, ammonium chloride, barium chloride and various alkali metal aluminum sulfates, aluminum chloride, aluminum hydroxide, aluminum sulfate, aluminum acetate, aluminum glycinate, zinc salt As such, divalent or trivalent metal salts such as magnesium or calcium salts such as zinc hydroxide and zinc sulfate can be used, and these can be used alone or in combination. Zinc chloride is particularly preferred. The addition amount of the metal salt is not limited, but is preferably in the range of 12 or less weight, especially 2 to 6 weight, based on 100 weight of the high-polymerization and low-polymerization aqueous resin. If the addition amount of zinc chloride is out of this range, the polyvinyl alcohol-based water-based adhesive agent containing glyoxal will gel, making it difficult to uniformly coat the adhesive. When zinc chloride is added, it is better to apply the adhesive immediately after preparation.

The adhesive according to the present invention can be produced simply by dissolving glyoxal and polyvinyl alcohol-based resin in water at the above-mentioned ratio, for example. Polyvinyl alcohol-type resin is normally apply | coated after storing at the temperature of 15-30 degreeC after manufacture. When it is out of this temperature range, the problem which degrades the external appearance quality of a polarizing plate tends to arise.

The mixing ratio of the polyvinyl alcohol-based resin and water used as the water-based adhesive is not particularly limited, but, for example, it is appropriate to make the high-polymerization and low-polymerization aqueous resins 1 to 10 weights, preferably 1 to 5 weights, relative to 100 weights of water. Do.

As described above, the adhesive according to the present invention contains a dialdehyde compound and a metal salt, and the above water-based adhesive has a great feature of maintaining proper processability and adhesive strength by mixing resins having different polymerization degrees. Since this adhesive is an aqueous adhesive which does not need to use an organic solvent substantially, there is no possibility of causing an environmental and worker health hazard, and it can promote high adhesive force and hardening reaction by containing glyoxal and a metal salt.

Next, the polarizing plate which concerns on this invention is demonstrated.

In the polarizing plate according to the embodiment of the present invention, in the polarizing plate in which the protective film is adhered to the at least one surface of the polarizing film by an adhesive, the above-described adhesive (the adhesive is sufficiently described above) will be used on at least one surface. It features. In the above configuration, a suitable configuration may be added as necessary, and all are included in the present invention. Here, the polarizing film is a meaning of light that may include not only polarizers but also other specific configurations added to the polarizers.

The polarizing film may be used without limitation any polarizing film known in the art and are included in the present invention. In particular, a polarizing film containing polyvinyl alcohol-based resin is preferable.

As for the polarizing film containing polyvinyl alcohol-type resin, it is preferable that the dichroic dye is adsorption-oriented specifically to the uniaxially stretched polyvinyl alcohol-type resin film. Polyvinyl alcohol-type resin which comprises a polarizing film is obtained by saponifying a polyvinyl acetate type resin. As polyvinyl acetate type resin, the copolymer etc. of vinyl acetate and the other monomer copolymerizable with it besides the polyvinyl acetate which is a homopolymer of vinyl acetate are illustrated. As another monomer copolymerized with vinyl acetate, unsaturated carboxylic acids, unsaturated sulfonic acids, olefins, vinyl ethers, acrylamide which has an ammonium group, etc. are mentioned, for example. Saponification degree of polyvinyl alcohol-type resin is about 85-100 mol% in total, Preferably it is 98 mol% or more. The polyvinyl alcohol-based resin may also be modified. For example, polyvinyl formal, polyvinyl acetal, or the like modified with aldehydes can also be used. In addition, the degree of polymerization of the polyvinyl alcohol-based resin is usually 1,000 to 10,000, preferably, it is preferable to mix different resins having a polymerization degree of about 1,000 to 5,000.

What formed such a polyvinyl alcohol-type resin film is used as a raw film of a polarizing film. The method of film-forming polyvinyl alcohol-type resin is not specifically limited, It can form film by a well-known method. Although the film thickness of a polyvinyl alcohol-type raw film is not specifically limited, For example, it is about 10-150 micrometers.

The polarizing film is usually a step of uniaxially stretching such a polyvinyl alcohol-based resin film, a step of dyeing the polyvinyl alcohol-based resin film with a dichroic dye to adsorb the dichroic dye, and a polyvinyl alcohol-based adsorbed dichroic dye. It manufactures through the process of processing a resin film with aqueous boric acid solution, and the process of washing with water after the process by this boric acid aqueous solution.

Uniaxial stretching may be performed before dyeing, simultaneously with dyeing, or after dyeing. When performing uniaxial stretching after dyeing, this uniaxial stretching may be performed before boric acid treatment, or may be performed during boric acid treatment. Of course, it is also possible to uniaxially stretch in these several steps. In uniaxial stretching, you may extend | stretch uniaxially between rolls with different circumferential speeds, and may extend | stretch uniaxially using a thermal roll. Moreover, it may be dry stretching, such as extending | stretching in air | atmosphere, or it may be wet extending | stretching extending | stretching in the state swollen with a solvent. The draw ratio is usually about 3 to 8 times.

In order to dye a polyvinyl alcohol-type resin film with a dichroic dye, a polyvinyl alcohol-type resin film can be immersed in the aqueous solution containing a dichroic dye, for example. As a dichroic dye, an iodine and a dichroic dye are used specifically. In addition, it is preferable that the polyvinyl alcohol-based resin film be immersed in water before the dyeing treatment.

When using iodine as a dichroic dye, the method of immersing and dyeing a polyvinyl alcohol-type resin film in the aqueous solution containing iodine and potassium iodide is employ | adopted normally. The content of iodine in this aqueous solution is usually about 0.01 to 1 part by weight per 100 parts by weight of water, and the content of potassium iodide is usually about 0.5 to 20 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution used for dyeing is about 20-40 degreeC normally, and the immersion time (dyeing time) in this aqueous solution is about 20-1,800 second normally.

On the other hand, when using a dichroic dye as a dichroic dye, the method of immersing and dyeing a polyvinyl alcohol-type resin film in the aqueous solution containing water-soluble dichroic dye is employ | adopted normally. The content of the dichroic dye in this aqueous solution is usually about 0.01 to 1 part by weight per 100 parts by weight of water, and the content of potassium iodide is usually about 1x10 ^-4 to 10 parts by weight per 100 parts by weight of water, preferably 1x10 ^-3 To about 1 part by weight. This aqueous solution may contain inorganic salts, such as sodium sulfate, as a dyeing adjuvant. The temperature of the dye aqueous solution used for dyeing is about 20-80 degreeC normally, and the immersion time (dyeing time) in this aqueous solution is about 10 to 1,800 second normally.

The boric acid treatment after dyeing with a dichroic dye is performed by immersing the dyed polyvinyl alcohol-type resin film in boric acid containing aqueous solution. The amount of boric acid in the boric acid-containing aqueous solution is usually about 2 to 15 parts by weight, preferably about 5 to 12 parts by weight per 100 parts by weight of water. When iodine is used as a dichroic dye, it is preferable that this boric acid containing aqueous solution contains potassium iodide. The amount of potassium iodide in the aqueous solution containing boric acid is usually about 0.1 to 15 parts by weight, preferably about 5 to 12 parts by weight per 100 parts by weight of water. Immersion time in boric-acid containing aqueous solution is about 60 to 1,200 second normally, Preferably it is about 150 to 600 second, More preferably, it is about 200 to 400 second. The temperature of the boric-acid containing aqueous solution is 50 degreeC or more normally, Preferably it is 50-85 degreeC, More preferably, it is 60-80 degreeC.

The polyvinyl alcohol-based resin film after boric acid treatment is usually washed with water. The water washing process is performed by immersing the polyvinyl alcohol-type resin film processed by boric acid in water, for example. The temperature of the water in a water washing process is about 5-40 degreeC normally, and immersion time is about 1 to 120 second normally. After water washing, a drying process is performed and a polarizing film is obtained. Drying process is normally performed using a hot-dryer and a far-infrared heater. The temperature of a drying process is about 30-100 degreeC normally, Preferably it is 50-80 degreeC. The drying treatment time is usually about 60 to 600 seconds, preferably about 120 to 600 seconds. In this way, the polyvinyl alcohol-based resin film is subjected to uniaxial stretching, dyeing with a dichroic dye, and boric acid treatment to obtain a polarizing film. The thickness of this polarizing film is about 5-40 micrometers.

The protective film is not particularly limited, and any protective film known in the art may be used and included in the present invention. For example, a cycloolefin resin film, a cellulose resin film, a film containing a polyester resin such as polyethylene terephthalate or polyethylene naphthalate, polybutylene terephthalate, a film containing a polycarbonate resin, or the like Can be mentioned.

The protective film is preferably at least one selected from cellulose-based and cycloolefin-based resins. The protective film may be bonded to one side of the polarizing film or may be bonded to both sides. When bonding the protective film containing cycloolefin resin to both surfaces of a polarizing film, two protective films may be the same kind, and may be another kind. For example, when bonding the protective film containing cycloolefin resin to one surface of a polarizing film, the protective film containing resin other than cycloolefin resin can be bonded to the opposite surface.

 A cellulose resin film may be a triacetyl cellulose film, a diacetyl cellulose film, etc., for example.

Cycloolefin resin is thermoplastic resin which has a unit of the monomer containing cyclic olefin (cycloolefin), such as a norbornene and a polycyclic norbornene-type monomer, for example. The cycloolefin resin may be an addition copolymer of a cycloolefin with an aromatic compound having a chain olefin or a vinyl group, in addition to the hydrogenated product of the ring-opening polymer of the cycloolefin or the ring-opening copolymer using two or more cycloolefins. It is also effective to introduce a polar group.

In the case of making a copolymer of a cycloolefin with a chain olefin or an aromatic compound having a vinyl group, ethylene or propylene as an example of the chain olefin can be cited, and examples of the aromatic compound having a vinyl group are styrene, α-methylstyrene, and nuclear alkyl. Substituted styrene, etc. are mentioned. In such a copolymer, the unit of the monomer containing a cycloolefin may be 50 mol% or less, for example, about 15-50 mol%. In particular, when made from the terpolymer of a cycloolefin and the aromatic compound which has a vinyl group, the unit of the monomer containing a cycloolefin may be comparatively small amount in this way. In such a terpolymer, the unit of the monomer containing a linear olefin is about 5 to 80 mol% normally, and the unit of the monomer containing the aromatic compound which has a vinyl group is about 5 to 80 mol% normally.

Although it is preferable that the thickness of a protective film is thin, when too thin, strength falls and it is inferior to workability, On the other hand, when too thick, problems, such as transparency fall or the weight of a polarizing plate become large, arise. Therefore, a suitable thickness of a protective film, especially a cycloolefin resin film, is about 5-200 micrometers, for example, Preferably it is 10-150 micrometers, More preferably, it is 20-100 micrometers.

In addition, the protective film may be subjected to surface treatment such as an antiglare treatment, a hard coating treatment, an antistatic treatment, an antireflection treatment, and the like on the opposite side of the surface to be bonded to the polarizing film. In addition, a coating layer containing a liquid crystalline compound, a high molecular weight compound thereof, or the like may be formed. When bonding the protective film containing cycloolefin resin to both surfaces of a polarizing film, such a surface treatment layer and a coating layer can be performed on the surface of one film, and contain cycloolefin resin in one surface of a polarizing film. When bonding the protective film to bond and bonding the protective film containing resin other than that to another surface, it can also implement on the surface of either protective film.

As the adhesive used to bond the polarizing film and the protective film, it is preferable to use the aforementioned adhesive on at least one surface. When laminating | stacking the protective film containing resin other than cycloolefin resin on one surface of a polarizing film, although the adhesive agent for it is not limited to the adhesive mentioned above, it is good to use the same adhesive on both surfaces because of ease of installation etc.

The method of adhering a protective film containing a polarizing film and a cycloolefin resin with an adhesive, and a method of adhering two films when laminating a protective film containing a resin other than a cycloolefin based on one surface of the polarizing film is usually It may be generally known, and the adhesive is applied to the adhesive side of the polarizing film and / or the protective film, for example, by a casting method, a meyer bar coating method, a gravure coating method, a die coating method, a dip coating method, a spraying method, or the like. To overlap the two films. The casting method is a method in which a polarizing film or a protective film, which is a coated object, is moved in an approximately vertical direction, approximately a horizontal direction, or in an inclined direction between two films while flowing an adhesive on its surface and applied widely. After apply | coating an adhesive agent, a polarizing film and a protective film are pinched together by a nip roll etc., and they are bonded together.

In addition, the present invention is characterized in that at least one of the polarizing film and the protective film is washed with an aqueous surfactant solution before bonding. Through this, in bonding the polarizing film and the protective film, it is possible to prevent the incorporation of foreign materials before bonding and increase the flowability of the adhesive to activate a specific surface for uniform application.

The surfactant may be used alone or in combination of two or more of a nonionic, anionic, cationic, amphoteric, fluorine, silicone, and polymeric surfactant. The said nonionic surfactant is a surfactant which does not have group which dissociates into an ion in aqueous solution, and has -OH group. Although relatively hydrophilic, they have ester, acid amide, and ether bonds in their molecules. Specific examples of nonionic surfactants include polyoxyethylene ethers and sorbitan esters of ether type glycerin esters such as alkyl and alkylaryl polyoxyethylene ethers, polyoxyethylene acetylenic diol ethers, and block polymers having polyoxypropylene as a lipophilic group. Ester ethers such as polyoxyethylene ethers, and polyoxyethylene ethers of sorbitan esters, polyethylene glycol fatty acid esters, glycerin esters, sorbitan esters, ester types such as propylene glycol esters, sugar esters and alkyl polyglucosides Nitrogen-containing types such as nolvamide, polyoxyethylenefatty acidamide, polyoxyethylenealkylamine, and amine oxide.

Specific examples of the anionic surfactants include higher fatty acid alkali salts (soaps), N-acrylamino acid salts, carboxylate alkyl sulfonates such as alkyl ether carbonates and acylated peptides, alkylbenzenes and alkylamino acid salts, alkylnaphthalenes, and the like. Sulfonic acid salts such as sulfonic acid salts, sulfonate sulfates, alkyl sulfates, alkyl ether sulfates, alkylaryl ether sulfates and alkylamide sulfates, and phosphate esters such as alkyl phosphates, alkyl ether phosphates and alkyl aryl ether phosphates There is a salt.

Specific examples of the cationic surfactant include aliphatic amine salts such as primary amine salts, secondary amine salts, tertiary amine salts and quaternary ammonium salts and quaternary ammonium salts thereof, aromatic quaternary ammonium salts and heterocycles. There is a quaternary ammonium salt.

Specific examples of the zwitterionic surfactants include betaine, sulfobetaine, imidazoline, glycine and aminopropion.

Specific examples of the fluorine-based surfactants include anionic such as perfluoroalkyl carboxylate, perfluoroalkyl sulfonate, perfluoroalkyl sulfate, perfluoroalkyl phosphate, perfluoroalkyl amine salt, and perfluoroalkyl quaternized ammonium salt. And amphoteric ionic systems such as perfluoroalkyl carboxy betaine, perfluoroalkyl sulfobetaine and nonionics such as fluorinated alkyl polyoxyethylene and perfluoroalcohol polyoxyethylene.

Specific examples of the silicone-based surfactants include polysiloxane glycol copolymers such as dimethylsiloxane glycol copolymer and trimethylsiloxane glycol copolymer.

Specific examples of the polymer-based surfactants include polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, polyacrylic acid-maleic acid copolymer, and poly 12-hydroxystearic acid.

In addition, the present invention in order to improve the adhesion between the film, at least one of the polarizing film and the protective film is bonded by at least one method of plasma treatment, corona treatment, ultraviolet irradiation treatment, flame (flame) treatment, and saponification treatment before bonding. It is characterized in that the surface treatment. As a saponification process, the method of immersing in aqueous alkali solution, such as sodium hydroxide and potassium hydroxide, is mentioned.

After laminating | stacking a polarizing film and a protective film, a drying process is performed. Although drying process is performed by spraying hot air, for example, the temperature at that time is suitably selected in the range of about 40-100 degreeC, Preferably it is 60-100 degreeC. The drying time is about 20 to 1,200 seconds. After drying, it is also preferable to cure for about 12 to 600 hours at a temperature of room temperature or slightly higher, for example, about 20 to 50 ° C. The thickness of the adhesive layer after drying is about 0.001-5 micrometers normally, Preferably it is 0.01 micrometer-2 micrometers, More preferably, it is 0.01-1 micrometer or less. When the thickness of the adhesive layer becomes thicker than 5 mu m, the appearance of the polarizing plate tends to be poor.

In the polarizing plate of the present invention, the optical functional film may be adhered to the surface of the protective film through an adhesive and included in the present invention. As an optical functional film, For example, the optical compensation film by which the liquid crystalline compound is apply | coated oriented on the surface of a base material, the reflection type polarization separation film which transmits polarized light of some kind, and reflects the polarized light which shows the opposite property, poly Retardation film containing carbonate resin, Retardation film containing cyclic polyolefin resin, Anti-glare function addition film which has uneven | corrugated shape on the surface, Surface anti-reflective treatment addition film, Reflective film with reflection function on surface, Reflection function And a semi-transmissive reflective film having both a transmissive function and the like.

Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited by these examples. In the examples,% and parts indicating the content to the amount of use are based on weight unless otherwise specified. Each Example and the evaluation result are shown in Table 1.

<Example>

Preparation of Polarizing Film

The polyvinyl alcohol film was conveyed in the order of a swelling tank, a dyeing tank, a first boric acid treatment tank, a second boric acid treatment tank, and a washing tank in order to produce a polarizing film.

The film was immersed for about 130 seconds in a polyvinyl alcohol film with a thickness of 75 µm with a width of 3,300 mm, an average degree of polymerization of about 2,400 and a degree of saponification of 99.9 mol% or more, in a pure water of about 30 ° C. for about 130 seconds while keeping the film in a tension state so as not to loosen. After sufficient swelling, uniaxial stretching was performed while dyeing by immersion in an aqueous solution of iodide / potassium iodide / water in a weight ratio of 0.02 / 1.5 / 100 (3 times magnification). Thereafter, potassium iodide / boric acid / water was immersed in an aqueous solution of about 60 ° C. having a weight ratio of 10/5/100, and uniaxial stretching was carried out until the accumulated draw ratio became 4.9 times from the master while boric acid treatment. Further, the second boric acid treatment was performed by immersing the potassium iodide / boric acid / water in an aqueous solution having a weight ratio of 10/3/100 by about 40 ° C. for about 30 seconds. After the second boric acid treatment, water was washed with pure water at about 10 ° C. for about 10 seconds. After washing with water, the resultant was dried at about 60 ° C. for 2 minutes to obtain a polarizing film having iodine adsorbed onto polyvinyl alcohol having a thickness of about 30 μm and a width of 1580 mm. After bonding a protective film on both surfaces of this polarizing film, it dried and manufactured the polarizing plate.

Shrinkage was measured by changing the length of the polyvinyl alcohol resin width before and after drying after bonding with the protective film.

<Example 1>

Based on 100 parts of water, Kurarefobal PVA117H (average degree of polymerization 1700, saponification degree 99.0 mol% or more) and cosenol Z-200 (average degree of polymerization 1000, saponification degree 99.0 mol% or more) with PVA-based water-soluble adhesive 1: To 4 parts of the aqueous adhesive mixed with 1, 1 part of glyoxal and 0.1 part of zinc chloride were added. On the polarizing film obtained previously, one side was triaxially oriented, 80 µm long, 1620 mm wide, and the other side was triacetylcellulose protective film 1, and the other side was biaxially stretched with a norbornene-based resin having a width of 1620 mm 70 corona-treated. A micrometer protective film 2 ("Zenoa film" manufactured by Optes Co., Ltd.) was bonded through the adhesive, and dried at 80 ° C. for 5 minutes to obtain a polarizing plate. The shrinkage rate before and after drying of the obtained polarizing plate was 0.06%. Thereafter, curing was performed at 40 ° C for 6 days. Although the blade was put in the transmission axis direction at the angle of 45 degrees of inclination with respect to the film normal line direction, the peeling of the polarizing film and this protective film was attempted at the surface of this polarizing plate, but it was not peeled at all.

<Example 2>

Based on 100 parts of water, Kurarefobal PVA117H (average degree of polymerization 1700, saponification degree 99.0 mol% or more) and cosenol Z-200 (average degree of polymerization 1000, saponification degree 99.0 mol% or more) with PVA-based water-soluble adhesive 1: To 4 parts of the aqueous adhesive mixed with 1, 1 part of glyoxal and 0.1 part of zinc chloride were added. On both sides of the polarizing film obtained above, a biaxially stretched norbornene-based resin film (protective film 2) having a thickness of 75 μm and a width of 1620 mm subjected to corona treatment, and a thickness of 70 μm and a width of 1620 mm without extending the other side Protective film (protective film 3) ("Zenoa film" manufactured by Optes Co., Ltd.) was bonded through the adhesive, and dried at 80 ° C for 5 minutes to obtain a polarizing plate. The shrinkage rate before and after drying of the obtained polarizing plate was 0.05%. Thereafter, curing was performed at 40 ° C for 6 days. The blade was placed on the surface of the polarizing plate in the transmission axis direction at an angle of 45 degrees inclination with respect to the film normal direction, and peeling of the polarizing film and this protective film was attempted, but it was not peeled at all.

<Example 3>

Based on 100 parts of water, Kurarefobal PVA117H (average degree of polymerization 1700, saponification degree 99.0 mol% or more) and cosenol Z-200 (average degree of polymerization 1000, saponification degree 99.0 mol% or more) with PVA-based water-soluble adhesive 1: To 4 parts of the aqueous adhesive mixed with 1, 1.5 parts of glyoxal and 0.1 part of zinc chloride were added. On both sides of the polarizing film obtained above, a biaxially stretched norbornene-based resin film (protective film 2) having a thickness of 75 μm and a width of 1620 mm subjected to corona treatment, and a thickness of 70 μm and a width of 1620 mm without extending the other side Protective film (protective film 3) ("Zenoa film" manufactured by Optes Co., Ltd.) was bonded through the adhesive, and dried at 80 ° C for 5 minutes to obtain a polarizing plate. The shrinkage rate after drying of the obtained polarizing plate was 0.06%. Thereafter, curing was performed at 40 ° C for 6 days. The blade was placed on the surface of the polarizing plate in the transmission axis direction at an angle of 45 degrees inclination with respect to the film normal direction, and peeling of the polarizing film and this protective film was attempted, but it was not peeled at all.

<Example 4>

The polarizing plate was prepared in the same manner as in Example 1 except that the polarizing film and the protective film resin were washed with an aqueous solution containing 1% of a cationic surfactant (SAT-6C, Japan Pure Chemical Co., Ltd.) before bonding the polarizing film and the protective film. Got it. The shrinkage rate after drying of the obtained polarizing plate was 0.07%. Thereafter, curing was performed at 40 ° C for 6 days. The blade was placed on the surface of the polarizing plate in the transmission axis direction at an angle of 45 degrees inclination with respect to the film normal direction, and peeling of the polarizing film and this protective film was attempted, but it was not peeled at all.

Comparative Example 1

3 parts of carboxyl group-modified polyvinyl alcohol (Kurere's "Kurerefobal KL318", average molecular weight: 85,000) and 100 parts of water and "Sumirez resin 650" manufactured by water-soluble polyamide epoxy resin (Sumitomo Chemical Co., Ltd.) A polarizing plate was produced in the same manner as in Example 1 except that 1.8 parts of (aqueous solution having a solid content concentration of 30%) were added to form an adhesive. The shrinkage rate after drying of the polarizing plate was 0.3%. Thereafter, curing was performed at 40 ° C for 6 days. The protective film peeled easily in the obtained polarizing plate.

Comparative Example 2

"Semirezu" manufactured by Kureray pour PVA117H (average degree of polymerization 1700, saponification degree 99.0 mol% or more) based on 100 parts of water and water-soluble adhesive 4 parts water-soluble polyamide epoxy resin (Sumitomo Chemical Co., Ltd.) A polarizing plate was prepared in the same manner as in Example 2 except that 1.8 parts of resin 650 ″ (an aqueous solution having a solid content of 30%) was added to form an adhesive. The shrinkage rate after drying of the polarizing plate was 0.5%. Thereafter, curing was performed at 40 ° C for 6 days. The protective film peeled easily in the obtained polarizing plate.

Comparative Example 3

Based on 100 parts of water, Kurerepoval PVA135H (average degree of polymerization 3500, saponification degree 99.0 mol% or more) and Kurarepoval PVA102 (average degree of polymerization 200, saponification degree 98.0 mol%) are mixed 1: 1 with PVA-based water-soluble adhesive A polarizing plate was produced in the same manner as in Example 1, except that 4 parts of an aqueous adhesive was used. The shrinkage rate after drying of the polarizing plate was 0.7%. Thereafter, curing was performed at 40 ° C for 6 days. The protective film peeled easily in the obtained polarizing plate.

<Comparative Example 4>

Based on 100 parts of water, Kurerefobal PVA103 (average degree of polymerization 300, saponification degree 98.0 mol%) and Kurerepoval PVA102 (average degree of polymerization 200, saponification degree 98.0 mol%) are mixed 1: 1 with PVA-based water-soluble adhesive A polarizing plate was produced in the same manner as in Example 2, except that 4 parts of an aqueous adhesive was used. The shrinkage rate after drying of the polarizing plate was 0.8%. Thereafter, curing was performed at 40 ° C for 6 days. The protective film peeled easily in the obtained polarizing plate.

TABLE 1

Protective film Adhesive Composition (100 parts by weight / water) washing Shrinkage Peeling phenomenon PVA 117H Z-200 KL 318 PVA 135H PVA 102 PVA 103 GLO EPO ZnCl ₂ Example 1 One 2 2 2 One 0.1 Not carried 0.06% none Example 2 3 2 2 2 One 0.1 Not carried 0.05% none Example 3 3 2 2 2 1.5 0.1 Not carried 0.06% none Example 4 3 2 2 2 One 0.1 practice 0.07% none Comparative Example 1 One 2 3 1.8 Not carried 0.30% has exist Comparative Example 2 3 2 4 1.8 Not carried 0.50% has exist Comparative Example 3 One 2 2 2 One 0.1 Not carried 0.50% has exist Comparative Example 4 3 2 2 2 One 0.1 Not carried 0.50% has exist

(Protective film 1: triacetyl cellulose protective film

Protective film 2: Biaxially oriented cycloolefin protective film

Protective Film 3: Unstretched Cycloolefin-Based Protective Film

GLO: Glyoxal

EPO: epoxy resin)

Since the adhesive according to the present invention has a high adhesive strength and appropriate processability, and is an aqueous adhesive that is not required for an organic solvent, there is no fear of causing environmental and worker health problems. In addition, the polarizing plate according to the present invention is excellent in adhesive strength between the polarizing film and the protective film by using an excellent adhesive, significantly reduced shrinkage, etc., excellent appearance and performance, and can be manufactured with higher production yield and reliability. .

Claims (11)

An adhesive comprising a high polymerization water resin, a low polymerization water resin, and a dialdehyde compound, wherein the difference in average polymerization degree between the high polymerization water resin and the low polymerization water resin is in the range of 300 to 3000. The adhesive according to claim 1, further comprising a metal salt. The adhesive of claim 1, wherein the water-based resin is polyvinyl alcohol (PVA). The adhesive according to claim 1, wherein the average degree of polymerization of the high-polymerization aqueous resin is in the range of 1500 to 3500, and the average degree of polymerization of the low-polymerization aqueous resin is in the range of 100 to 1500. The adhesive of claim 1, wherein the dialdehyde compound is selected from at least one of glyoxal, terephthalaldehyde and glutaraldehyde. 3. The adhesive of claim 2 wherein the metal salt is zinc chloride. In the polarizing plate wherein the protective film is bonded with an adhesive on at least one side of the polarizing film, The adhesive of any one of Claims 1-6 is used for at least one surface, The polarizing plate characterized by the above-mentioned. The polarizing plate of claim 7, wherein the polarizing film is polyvinyl alcohol-based. The polarizing plate of claim 7, wherein the protective film is selected from at least one of cellulose and cycloolefin. The polarizing plate of claim 7, wherein at least one of the polarizing film and the protective film is washed with an aqueous surfactant solution before bonding. The method of claim 7, wherein at least one of the polarizing film and the protective film is surface-treated by at least one of plasma treatment, corona treatment, ultraviolet irradiation treatment, flame treatment, and saponification treatment before bonding. Polarizing plate.