KR20070096826A - Polarizing plate and process for producing the same - Google Patents

Abstract

A polarizing plate and a manufacturing method thereof are provided to restrict curls of the polarizing plate by regulating the water content rate of an acetylcellulose film over 0.5% before laminating the acetylcellulose film. In a polarizing plate(1), a cycloolefin resin film is laminated on one surface of a polarizing film(1) containing polyvinyl alcohol resin, by an adhesive agent and an acetylcellulose film is laminated on the other surface by an adhesive agent. The water content rate before laminating the acetylcellulose film is controlled over 0.5wt.%. The acetylcellulose film is dipped in the water at 10~45 degree for 1~60 seconds and then dried before lamination at 40~60 degree for 20~60 seconds. The water content rate of the film after the dipping and drying processes is kept over 0.5wt.%.

Description

Polarizing plate and manufacturing method thereof {Polarizing Plate and Process for Producing the Same}

FIG. 1: is a perspective view which shows typically the curl amount measurement state of the polarizing plate in an Example.

<Brief description of symbols for the main parts of the drawings>

1: Curled Polarizer

3: imaginary plane on the reference plane assuming the polarizer is not curled

5: reference plane

A, B, C, D: Corner on virtual plane

A1, B1. C1, D1: edge of curled polarizer

H: amount of curl (height from the reference plane to the edge of the polarizer)

[Patent Document 1] Japanese Unexamined Patent Application Publication No. 5-212828

[Patent Document 2] Japanese Patent Application Laid-Open No. 2005-70140

[Patent Document 3] Japanese Unexamined Patent Application Publication No. 2005-181817

[Patent Document 4] Japanese Patent Application Laid-Open No. 2005-208456

[Patent Document 5] Japanese Patent Application Laid-Open No. 2005-352011

The present invention relates to a polarizing plate in which a cycloolefin-based resin film is laminated on one side of a polarizing film containing polyvinyl alcohol-based resin via an adhesive, and a cellulose acetate-based film is laminated on the other side by an adhesive, and a method of manufacturing the same. will be. Specifically, the present invention relates to a polarizing plate and a manufacturing method thereof, in which curling is suppressed so that mixing of bubbles is less likely to occur when bonding to a liquid crystal cell even when such a polarizing film is sandwiched.

The polarizing plate is obtained by laminating a transparent resin film, for example, a cellulose acetate-based protective film represented by, for example, triacetyl cellulose, through an adhesive on both sides of a polarizing film containing a polyvinyl alcohol-based resin in which a dichroic dye is adsorbed and oriented. It is composed. Moreover, by bonding the optical film drawn by the cycloolefin resin film etc. to a polarizing plate, when it applies to a liquid crystal cell and makes a liquid crystal display device, visibility from various angles is improved and a favorable viewing angle is obtained.

It is known to bond a cycloolefin resin film to a polyvinyl alcohol-based polarizing film. For example, JP-A-5-212828 (Patent Document 1) discloses at least one surface of a polyvinyl alcohol-based sheet. It is described that a thermoplastic saturated norbornene-based resin sheet is laminated, heat-compression-bonded, and made into a polarizing plate through an acrylic pressure sensitive adhesive. However, since the pressure-sensitive adhesives (also called pressure-sensitive adhesives) such as acrylics have their own thicknesses of about 10 to 50 µm, the liquid crystal display cannot be thickened, and it is troublesome to bond the polarizing film and the cycloolefin resin film one by one. Accompanied by remorse.

On the other hand, it is also known to bond a cycloolefin resin film to the polarizing film containing polyvinyl alcohol-type resin via an adhesive agent, for example, Unexamined-Japanese-Patent No. 2005-70140 (patent document 2), Unexamined-Japanese-Patent No. In 2005-187817 (Patent Document 3) and Japanese Patent Laid-Open No. 2005-208456 (Patent Document 4), a urethane resin, particularly a polyester ionomer-type urethane resin, is used in a polarizing film containing a polyvinyl alcohol-based resin. Laminating | stacking a cycloolefin resin film is described through the water-based adhesive agent containing. According to the techniques described in these publications, a cycloolefin-based protective film can be directly laminated on a polyvinyl alcohol polarizing film by a roll-to-roll method.

Among these, in Example 2 of patent documents 2 and 3, the film of norbornene-type resin which is one type of cycloolefin resin on one side of a polyvinyl alcohol-type polarizing film, and the triacetyl cellulose film on the other side, respectively, A polarizing plate is described by bonding through a urethane-based adhesive, and Patent Document 4 describes a water-based compound containing a compound having a polyester-ionomer-type urethane resin and a glycidyloxy group on one side of a polyvinyl alcohol-based polarizing film. A cycloolefin resin film is laminated through a first adhesive, and on the other side, a cellulose acetate film is applied through an aqueous second adhesive, such as an aqueous solution of a polyvinyl alcohol resin, having a composition different from that of the first adhesive. It is disclosed to form a polarizing plate by layering.

Japanese Unexamined Patent Application Publication No. 2005-352011 (Patent Document 5) also discloses a polarizing plate in which a cycloolefin-based resin film is laminated on one side of a polarizing film and a cellulose acetate-based film is laminated on the opposite side.

As disclosed in Patent Literatures 2 to 5, a polarizing plate in which a cycloolefin resin film is bonded to one surface of a polyvinyl alcohol polarizing film and a cellulose acetate film is bonded to the other surface of the polyvinyl alcohol polarizing film Symmetry and planarity are impaired compared with the polarizing plate which bonded the cellulose acetate type protective film on both surfaces. Therefore, the big curl which recessed the cycloolefin type protective film side tends to generate | occur | produce, and in this case, there existed a problem that air bubbles mixed in at the time of bonding to a liquid crystal cell.

Accordingly, an object of the present invention is to laminate a cycloolefin-based resin film on one side of a polarizing film containing polyvinyl alcohol-based resin through an adhesive, and to laminate a cellulose acetate-based film on the other side through an adhesive. It is to suppress curl which is easy to occur.

That is, according to the present invention, the cycloolefin-based resin film is laminated on one side of the polarizing film containing polyvinyl alcohol-based resin through the adhesive, the cellulose acetate-based film is laminated on the other side by the adhesive, acetic acid The polarizing plate in which the moisture content before lamination of a cellulose film is adjusted to 0.5% or more is provided. Thus, the curl which tends to generate | occur | produce in a polarizing plate can be suppressed by adjusting the moisture content of the cellulose acetate type film before bonding to a polarizing film.

In addition, according to the present invention, a cycloolefin-based resin film is laminated on one side of a polarizing film containing polyvinyl alcohol-based resin through an adhesive, and a cellulose acetate-based film is laminated on the other side by an adhesive to produce a polarizing plate. When it does, the manufacturing method of the polarizing plate which adjusts the moisture content before lamination of a cellulose acetate type film to 0.5% or more is also provided.

Best Mode for Carrying Out the Invention

Hereinafter, the present invention will be described in detail. The polarizing plate of this invention laminates a cycloolefin resin film on one side of the polarizing film containing polyvinyl alcohol-type resin via an adhesive agent, and laminates the cellulose acetate type film on the other side via an adhesive agent.

In the polarizing film containing polyvinyl alcohol-type resin, a dichroic dye is adsorbed-oriented specifically to the polyvinyl alcohol-type resin film uniaxially stretched.

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 this 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. The saponification degree of polyvinyl alcohol-type resin is about 85-100 mol% normally, Preferably it is 98 mol% or more. The polyvinyl alcohol-based resin may be modified. For example, polyvinyl formal, polyvinyl acetal, or the like modified with aldehydes may also be used. In addition, the degree of polymerization of the polyvinyl alcohol-based resin is usually about 1,000 to 10,000, preferably about 1,500 to 5,000.

What formed such a polyvinyl alcohol-type resin into a film is used as a raw film of a polarizing film. The method of forming a polyvinyl alcohol-type resin into a film is not specifically limited, It can form into a 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 and adsorbing the dichroic dye, and a polyvinyl adsorbed with a dichroic dye. It manufactures through the process of processing an alcoholic 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 uniaxial stretching is performed 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. At the time of uniaxial stretching, you may extend | stretch to 1 axis between rolls from which a circumferential speed differs, and you may extend | stretch to 1 axis using a hot roll. Moreover, it may be dry stretching, such as extending | stretching in air | atmosphere, or wet extending | stretching which extends in the state swelled with a solvent may be sufficient. The draw ratio is usually about 2 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, the polyvinyl alcohol-based resin film is preferably subjected to a water immersion treatment 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 used 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) with respect to 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 used normally. The content of the dichroic dye in this aqueous solution is usually about 1 × 10 ^-4 to 10 parts by weight, preferably about 1 × 10 ^-3 to 1 part by weight per 100 parts by weight of water. 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) with respect to this aqueous solution is about 10-1,800 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 aqueous solution containing boric acid 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 using iodine 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. The immersion time for the boric acid-containing aqueous solution is usually about 60 to 1,200 seconds, preferably about 150 to 600 seconds, more preferably about 200 to 400 seconds. 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 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. A drying process is normally performed using a hot air dryer or a far infrared heater. The temperature of a drying process is about 30-100 degreeC normally, Preferably it is 50-80 degreeC. The time of the drying treatment 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. In this invention, a cycloolefin resin film is laminated | stacked on one side of this polarizing film via an adhesive agent, and a cellulose acetate type film is laminated | stacked on the other side through an adhesive agent.

Cycloolefin resin is thermoplastic resin which has a unit of the monomer containing cyclic olefin (cycloolefin) like a norbornene and a polycyclic norbornene-type monomer, for example. This cycloolefin resin may not only be a hydrogenated product of the ring-opening polymer of the said cycloolefin, or the ring-opening copolymer using 2 or more types of cycloolefins, but also an addition copolymer, such as an aromatic compound which has a cycloolefin, a linear olefin, and a vinyl group. have. It is also effective to introduce a polar group.

In the case of using a copolymer of a cycloolefin and a chain olefin or an aromatic compound having a vinyl group, examples of the chain olefin include ethylene and propylene. Examples of the aromatic compound having a vinyl group include styrene, α-methyl styrene, and nuclear alkyl substituted styrene. Can be mentioned. In such copolymers, the units of monomers comprising cycloolefins may be up to 50 mol%, for example on the order of 15 to 50 mol%.

In particular, in the case of using a ternary copolymer of a cycloolefin, a chain olefin, and an aromatic compound having a vinyl group, the unit of the monomer containing the cycloolefin may be a relatively small amount as described above. In such a terpolymer, the unit of the monomer containing the linear olefin is usually about 5 to 80 mol%, and the unit of the monomer containing the aromatic compound having a vinyl group is usually about 5 to 80 mol%.

Commercially available thermoplastic cycloolefin-based resins include "Topas" sold by Ticona, Germany, "Aton" sold by JSR, and Nippon Xeon sold " "ZEONOR" and "ZEONEX", "Apel" etc. (all brand names) sold by Mitsui Chemicals, Inc. are mentioned. Such a cycloolefin-based resin is formed into a film, and a known method such as a solvent casting method and a melt extrusion method is suitably used for the film formation. A cycloolefin resin film produced is also commercially available. For example, "Esshina" and "SCA40" sold by Sekisui Kagaku Kogyo Co., Ltd., "Zenoa Film" sold by Optes, Inc. Etc. (all are brand names).

The cycloolefin-based resin film may be stretched uniaxially or biaxially, and may exhibit predetermined birefringence characteristics. The draw ratio in this case is about 1.1 to 5 times normally, Preferably it is 1.1 to 3 times.

In this invention, the cellulose acetate film used as another protective film is a cellulose partial or complete acetate ester, and a triacetyl cellulose film, a diacetyl cellulose film, etc. are mentioned, for example. Commercially available triacetyl cellulose films include "Fujitec TD80", "Fujitec TD80UF" and "Fujitec TD80UZ" sold by Fuji Shashin Film Co., Ltd., "KC8UX2MW" sold by Konica Minolta Opto Corporation, and "KC8UY" and the like.

It is preferable to perform a saponification process on the surface of a cellulose acetate type film in order to raise the adhesive force with an adhesive agent. Saponification can be performed by the method of immersing in aqueous solution of alkali, such as sodium hydroxide and potassium hydroxide.

And in this invention, it is made so that the moisture content before bonding a cellulose acetate type film to a polyvinyl alcohol-type polarizing film may be 0.5 weight% or more. Thus, it was discovered that the curl of the polarizing plate obtained is largely suppressed by adjusting the moisture content of a cellulose acetate type film. The upper limit of the moisture content is allowed up to about 3% by weight.

In order to adjust the moisture content of a cellulose acetate type film, the method of immersing in water as a pretreatment of bonding of this film, for example, and then drying until it reaches a predetermined moisture content can be used. In the first treatment step of this pretreatment, the solution is immersed in water for 1 to 60 seconds at a temperature of 10 to 60 ° C., preferably 10 to 50 ° C. to swell. When the temperature at this time is too high, a stripe defect may occur, Preferably it is performed at the temperature of 50 degrees C or less, More preferably, it is 10-45 degreeC. Even if lengthening the immersion time in water is limited, the absorption amount is limited, so usually within 30 seconds is sufficient.

In the following 2nd process process, the drying process of the surface of a cellulose acetate type film is performed. A drying process is normally performed using a hot air dryer or a far infrared heater. The temperature of a drying process is about 30-100 degreeC normally, and the time of a drying process is about 20 to 600 second normally, and a drying process is performed on the conditions which the water content of a cellulose acetate type film is maintained at 0.5 weight% or more. That is, a drying process is performed for a relatively long time at low temperature, and a relatively short time at high temperature. Since the moisture content of a cellulose acetate type film is largely dependent on drying conditions, appropriate conditions are selected preferably from a drying temperature of 40-60 degreeC and about 20 to 60 second of drying time.

The cellulose acetate-based film may be subjected to surface treatment such as antiglare treatment, hard coating treatment, antistatic treatment, antireflection treatment and the like on the surface opposite to the surface to be bonded to the polarizing film. Moreover, the coating layer containing a liquid crystalline compound, its high molecular weight compound, etc. may be formed.

The thickness of each of the cycloolefin-based resin film and the cellulose acetate-based film disposed on both sides of the polarizing film is preferably thin. However, if the thickness is too thin, the strength decreases and the workability is insufficient, while if too thick, the transparency or the weight of the polarizing plate The problem arises that this becomes large. Therefore, the suitable thickness of a cycloolefin resin film is about 5-200 micrometers, for example, Preferably it is 10-150 micrometers, More preferably, it is 20-100 micrometers. Moreover, the suitable thickness of a cellulose acetate type film is about 20-200 micrometers, Preferably it is 20-100 micrometers.

One side of the polarizing film is laminated with a cycloolefin resin film as described above through an adhesive, and the other side with the adhesive is also laminated with a cellulose acetate-based film as described above through an adhesive to form a polarizing plate.

The adhesive used for bonding the polarizing film and the cycloolefin resin film, or the adhesive used for bonding the polarizing film and the cellulose acetate film, is water-based from the viewpoint of thinning the adhesive layer, that is, the adhesive component is dissolved in water or in water. Preferably dispersed. For example, the composition using polyvinyl alcohol-type resin and a urethane resin as a main component is mentioned as a preferable adhesive agent. Moreover, as long as suitable adhesiveness is obtained, it is preferable that the adhesive agent applied to both surfaces of a polarizing film is the same composition, because a manufacturing process can be simplified.

When polyvinyl alcohol-based resin is used as the main component of the adhesive, the polyvinyl alcohol-based resin may be modified with carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, methylol group modification, in addition to partially saponified polyvinyl alcohol or fully saponified polyvinyl alcohol. It may be a modified polyvinyl alcohol-based resin such as polyvinyl alcohol and amino group-modified polyvinyl alcohol. When using polyvinyl alcohol-type resin, the aqueous solution turns into an adhesive agent. The concentration of the polyvinyl alcohol-based resin in the adhesive is usually about 1 to 10 parts by weight, preferably 1 to 5 parts by weight based on 100 parts by weight of water.

In order to improve adhesiveness, it is preferable to add curable components, such as glyoxal and a water-soluble epoxy resin, or a crosslinking agent to the adhesive agent containing the aqueous solution of polyvinyl alcohol-type resin. The water-soluble epoxy resin is, for example, a polyamide obtained by reacting epichlorohydrin with a polyamide polyamine obtained by the reaction of a polyalkylene polyamine such as diethylenetriamine or triethylenetetramine and a dicarboxylic acid such as adipic acid. It may be an epoxy resin. As a commercial item of such a polyamide epoxy resin, "WS-525" sold by Sumitomo Chemtex Co., Ltd. "Smireze Resin 650", "Sumireze Resin 675", and Nippon PMC Co., Ltd., for example. "And so on. The addition amount of these curable components-a crosslinking agent is 1-100 weight part normally, Preferably it is 1-50 weight part as solid content with respect to 100 weight part of polyvinyl alcohol-type resins. When this addition amount is small, the adhesive improvement effect will reduce. On the other hand, when there is much addition amount, there exists a tendency for an adhesive bond layer to become weak.

When using urethane resin as a main component of an adhesive agent, the mixture of the polyester type ionomer type urethane resin and the compound which has glycidyloxy group is mentioned as an example of a suitable adhesive composition. The polyester ionomer-type urethane resin here is a urethane resin which has a polyester frame | skeleton, and a small amount of ionic component (hydrophilic component) is introduce | transduced in it. Such an ionomer-type urethane resin is suitable as an aqueous adhesive since it is emulsified directly in water, without using an emulsifier. The polyester ionomer-type urethane resin itself is already known, for example, described in Japanese Unexamined Patent Application Publication No. Hei 7-97504 as an example of a polymer dispersant for dispersing a phenolic resin in an aqueous medium. Patent Documents 2 to 4 describe a form in which a cycloolefin resin film is bonded to a polarizing film containing a polyvinyl alcohol resin using a mixture of a polyester ionomer-type urethane resin and a compound having a glycidyloxy group as an adhesive. have.

Polyester-type ionomer type urethane resin can be manufactured by the method of emulsifying hydrophilic group containing urethane resin obtained by making a hydrophilic group containing compound, polyester polyol, and polyisocyanate react, for example in water. At this time, not only polyester polyol but other high molecular weight polyol components and low molecular weight active hydrogen containing compound can be used together. As high molecular weight polyol, polyether polyol, polycarbonate polyol, polyacetal polyol, polyacrylate polyol, polyesteramide polyol, polythioether polyol, etc. are mentioned, for example. As the low molecular weight active hydrogen-containing compound, for example, polyhydroxy compounds such as ethylene glycol, neopentyl glycol, 1,6-hexanediol, glycerin and trimethylolpropane, diamine compounds such as ethylenediamine and piperazine, and the like Can be mentioned. Among these, it is a preferable form to use together a low molecular weight active hydrogen containing compound.

It is preferable that the weight average molecular weights of polyester-type ionomer type urethane resin are 5,000 or more, More preferably, they are 10,000 or more and 300,000 or less. If this weight average molecular weight is less than 5,000, the strength of an adhesive bond layer will not fully be obtained, but if it is larger than 300,000, the viscosity at the time of making this an aqueous dispersion becomes difficult, and handling becomes difficult.

Such a polyester ionomer-type urethane resin becomes an aqueous adhesive in the state disperse | distributed in water. It is preferable in handling that the viscosity of this aqueous adhesive is 2,000 mPa * sec or less, It is more preferable that it is 1,000 mPa * sec or less, It is especially preferable that it is 500 mPa * sec or less. The lower the viscosity, the easier it is to apply the adhesive, and the appearance of the obtained polarizing plate is also good. The solid content concentration of the polyester ionomer-type urethane resin in this water-based adhesive agent is preferably in the range of 10 to 70% by weight, more preferably 20% by weight or more, further preferably 50% by weight or less from the viewpoint of viscosity and adhesive strength. desirable.

In addition to the aqueous dispersion of the polyester ionomer-type urethane resin, polyethylene glycol, polyoxyethylene, etc., surfactant, etc. can also be added. In addition, water-soluble resins such as polyhydroxyethyl methacrylate, polyhydroxyethyl acrylate, polyacrylic acid and polyvinyl alcohol-based resins may be added.

As a commercial polyester ionomer type urethane resin, "Hylan AP-20", "Hylan APX-101H" etc. which are sold from Dainippon Ink & Chemical Co., Ltd. are mentioned, for example.

It is preferable that the adhesive agent containing the aqueous dispersion of polyester-type ionomer-type urethane resin contains the compound which has glycidyloxy group further. By using together the compound which has glycidyloxy group, the adhesiveness of a polarizing film and the cycloolefin resin film or cellulose acetate type film laminated | stacked on this improves. The glycidyloxy group referred to here is also referred to as 2,3-epoxypropoxy group in pure chemical terms. Examples of the compound having a glycidyloxy group include polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, polytetramethylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, diglycerin di Glycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, bisphenol A diglycidyl Ether, bisphenol F diglycidyl ether, resorcin diglycidyl ether, glycerin triglycidyl ether, trimethylol propane triglycidyl ether, pentaerythritol polyglycidyl ether, sorbitol polyglycidyl ether, sorbitan Polyglycidyl ether, polyglycerol polyglycidyl ether, and the like.

The mixing ratio of the polyester ionomer-type urethane resin and the compound having a glycidyloxy group is in the range of about 5 to 100 parts by weight of the compound having a glycidyloxy group with respect to 100 parts by weight of the solid content of the polyester-based ionomer type urethane resin. It is preferable to select suitably as much as possible, It is more preferable to select the compound which has glycidyloxy group in the range of 5 to 60 weight part, It is especially preferable to select to be in the range of 5-30 weight part. If the ratio of the compound having a glycidyloxy group is too low, sufficient adhesive strength will not be obtained. If the ratio is too large, the viscosity of the adhesive becomes high and handling becomes difficult.

Aqueous adhesives containing a polyester ionomer-type urethane resin and a compound having a glycidyloxy group are preferable from the viewpoint of environment and worker's health, since the organic solvent does not need to be substantially used, and a compound having a glycidyloxy group. By using together, high adhesive force is provided.

When using a polyester ionomer type urethane resin as an adhesive agent, in order to improve adhesiveness with respect to a cellulose acetate type film, it is preferable to use together the compound which has an isocyanate group, especially the polyisocyanate compound which has two or more isocyanate groups in a molecule | numerator. As such an isocyanate group containing compound, For example, monomers, such as 2, 4- tolylene diisocyanate, phenylene diisocyanate, 4,4'- diphenylmethane diisocyanate, 1, 6- hexamethylene diisocyanate, and isophorone diisocyanate, or Oligomers and reactants of these compounds with polyols. For this reason, 1, 3- propanediol, 1, 3- butanediol, 1, 4- butanediol, 1, 5- pentanediol, etc. are mentioned as a polyol to be used. The molecular weight of these isocyanate group-containing compounds is preferably 5,000 or less in terms of weight average molecular weight even in the case of reactants with the above-described oligomers and polyols. As a preferable commercial isocyanate group containing compound, "hydran assist Cl" etc. which are sold from Dainippon Ink & Chemical Co., Ltd. are mentioned, for example.

The mixing ratio of the polyester ionomer-type urethane resin and the isocyanate group-containing compound is appropriately selected so that the isocyanate group-containing compound is in the range of 5 to 100 parts by weight based on 100 parts by weight of the solid content of the polyester-based ionomer type urethane resin. Preferably, the isocyanate group-containing compound is more preferably selected to be in the range of 5 to 60 parts by weight, and particularly preferably selected to be in the range of 5 to 30 parts by weight. If the ratio of the isocyanate group-containing compound is too low, sufficient adhesive strength cannot be obtained. If the ratio is too large, the viscosity of the adhesive becomes high and handling becomes difficult.

The method of bonding a cycloolefin-based resin film or a cellulose acetate film to the polarizing film with an adhesive is generally generally known. For example, a casting method, a meyer bar coating method, a gravure coating method, a die coating method, and a dip coating method And a method of polymerizing both by applying an adhesive to the adhesive surface of the polarizing film and / or the film bonded thereto by the spraying method or the like. A casting method is a method in which the film, which is a coated object, is moved in an approximately vertical direction, an approximately horizontal direction, or in an inclined direction between the two, while expanding the adhesive by dripping the adhesive on the surface thereof. After apply | coating an adhesive agent, a polarizing film and the film bonded to it are pinched together by a nip roll etc., and are bonded.

Moreover, in order to improve adhesiveness, surface treatments, such as a plasma treatment, a corona treatment, an ultraviolet irradiation treatment, a flame | frame (flame) treatment, and saponification treatment, can be suitably applied to an adhesive surface.

After laminating | stacking a cycloolefin resin film on one side of a polarizing film and laminating a cellulose acetate type film on the other side, a drying process is performed. Although drying process is performed by spraying hot air, for example, the temperature at this time is suitably selected from the range of about 40-100 degreeC, Preferably it is 60-100 degreeC. The drying time is about 20 to 1,200 seconds.

The thickness of the adhesive bond layer after drying is about 0.001-5 micrometers normally, Preferably it is 0.01 micrometer or more, More preferably, it is 2 micrometers or less, More preferably, it is 1 micrometer or less. If the thickness of the adhesive layer becomes too large, the polarizing plate tends to be poor in appearance.

Sufficient adhesive strength is obtained by curing at least half a day, usually several days or more at a temperature of room temperature or more after the bonding. Preferred curing temperature is 30-50 degreeC, More preferably, it is 35-45 degreeC. When the curing temperature is 50 ° C or more, so-called tight winding is likely to occur in the roll winding state. In addition, the humidity at the time of curing is not specifically limited, The relative humidity may be in the range of about 0% RH-about 70% RH. The curing time is usually 1 day to 10 days, preferably 2 day to 7 days.

In the polarizing plate of the present invention, the optical functional film may be adhered to the surface of the cellulose acetate film disposed on the side opposite to the cycloolefin resin film via an adhesive.

As the optical functional film, for example, a reflection type polarization separation that reflects polarized light that transmits a specific polarized light and is directed to an optical compensation film orientated by aligning a liquid crystalline compound on the surface of the substrate. A film, the anti-glare function provision film which has an uneven | corrugated shape on the surface, the surface antireflection processing implementation film, the reflection film which has a reflection function, the semi-transmissive reflection film which has a reflection function and a transmission function, etc. are mentioned. As a commercial item corresponded to the optical compensation film which is oriented by carrying a liquid crystalline compound on the surface of a base material, "WV film" sold by Fuji Shashin Film Co., Ltd. and "NH film sold by Shin-Nippon Seki Oil Co., Ltd." And "NR films" (both trade names). As a commercial item corresponding to the reflection type polarizing separation film which transmits specific polarized light and reflects the polarized light showing the opposite property, it is sold by Minnesota Mining and Manufacturing Co., Ltd. (3M) (Sumitomo 3M Co., Ltd. in Japan). "DBEF" (brand name), and the like.

<Example>

Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited by these examples. In the examples,% and parts representing the content to the amount used are based on weight unless otherwise specified.

Production Example 1 Production of Polarizing Film

A polyvinyl alcohol film having a thickness of 75 µm having an average degree of polymerization of about 2,400 and a degree of saponification of 99.9 mol% or more was uniaxially stretched about 5 times by dry, and immersed in pure water at 60 ° C. for 1 minute while maintaining a tension state, followed by iodine / It was immersed at 28 degreeC for 60 second in the aqueous solution which weight ratio of potassium iodide / water is 0.05 / 5/100. Then, it was immersed at 72 degreeC for 300 second in aqueous solution whose weight ratio of potassium iodide / boric acid / water is 8.5 / 8.5 / 100. Subsequently, the resultant was washed with pure water at 26 ° C. for 20 seconds, and then dried at 65 ° C. to obtain a polarizing film in which iodine was adsorbed and oriented to the polyvinyl alcohol resin.

Production Example 2 Preparation of Adhesive

3 parts of carboxyl group-modified polyvinyl alcohol ("Kurere foam KL318" obtained from Kuraray) and water-soluble polyamide epoxy resin ("Sumireze resin 650 obtained from Sumitomo Chemtex") in 100 parts of water 1.5 parts of ((water solution of 30% of solid content concentration)) were added, and it was set as the polyvinyl alcohol-type adhesive agent.

Reference Example 1 Pretreatment of Triacetylcellulose Film

A triacetyl cellulose film ("KC8UX2MW" obtained from Konica Minolta Opto Co., Ltd.) having a thickness of 80 µm was saponified, followed by immersion for 10 seconds in water at the temperature described in the section of the water temperature of Table 1, followed by swelling treatment. After that, drying was performed for 53 seconds at each of the temperatures described in the section of the drying temperatures in Table 1, and then used in the bonding of Comparative Examples 1 to 2 and Examples 1 to 3 below.

The moisture content of this state was calculated | required by the weight reduction method as follows. That is, 100 mm × 100 mm small pieces were cut from the same film, immersed and dried in water under the same conditions as described above, and then weighed. Then, the sample was held in an oven at 100 ° C. for 1 hour and then weighed. Was measured and the moisture content was calculated | required from the weight difference of both. As an average value of five samples, the result shown in Table 1 was obtained.

[Comparative Examples 1-2 and Examples 1-3]

On one side of the polarizing film obtained in Production Example 1, a 73 μm-thick protective film containing norbornene-based resin was bonded to the other side via the adhesive obtained in Production Example 2, and on the other side, the same adhesive was used as in Reference Example 1 After bonding each triacetylcellulose film which pretreated, it dried at the temperature of 50 degreeC-90 degreeC for 5 minutes, and obtained the polarizing plate.

Each polarizing plate was cut into a rectangle of 15 cm × 20 cm in size so that each side had an angle of 45 ° with respect to the absorption axis (stretching direction), and the humidity was adjusted for 1 hour at a temperature of 23 ° C. and a relative humidity of 50%. Then, the curl amount was measured. The results are shown in Table 1.

In addition, the curl amount of the polarizing plate was measured as follows. That is, as shown in Fig. 1, the polarizing plate 1 curled on the reference plane 5 (e.g., a plane on a table, etc.) is positioned with its concave surface facing up. In this figure, the surface in the case where it is assumed that there is no curl in a polarizing plate is shown as the virtual surface (3) represented by rectangle (A), (B), (C), (D). And one edge A in the imaginary plane 3 is at the position of (A1) in the curled polarizing plate 1, and the other edge C is in the position of (C1) in the curled polarizing plate 1. In the curled polarizing plate 1, separate edges (B) and (D) are at the positions of (B1) and (D1), (B1) and (B) are the same position, and (D1) and (D ) Are also shown to be in the same position (that is, equivalent to the uncurled state at the edges (B) and (D) of the polarizer). In practice, however, three of four corners of the polarizing plate or all four corners may be curled. In this way, the height (H) from a reference surface is measured about each of the four corners (A1), (Bl), (C1), and (D1) of the polarizing plate, and negative when the norbornene-based resin film side is concave. When the curl and the norbornene-based resin film side were convex, the amount of curl was indicated by these minimum and maximum values as positive curl.

In Table 1, "<-50 mm" in "polarizing plate" and "curl amount" of the comparative example 1 is the curl which the norbornene-type resin film side concave, The absolute value is larger than 50 mm, ie A sign of a positive sign means less than -50 mm.

As can be seen from Table 1, the generation of curls could be controlled by adjusting the moisture content of the triacetylcellulose film before lamination.

According to the present invention, the occurrence of curl can be reduced in the asymmetric polarizing plate in which a cycloolefin resin film is laminated on one side of the polyvinyl alcohol polarizing film, and a cellulose acetate film is laminated on the other side. .

Claims (4)

Cycloolefin-based resin film is laminated on one side of the polarizing film containing polyvinyl alcohol-based resin through an adhesive, cellulose acetate-based film is laminated on the other side via an adhesive, and before the lamination of the cellulose acetate-based film The moisture content is adjusted to 0.5 weight% or more, The polarizing plate characterized by the above-mentioned. When manufacturing a polarizing plate by laminating a cycloolefin-based resin film on one side of a polarizing film containing polyvinyl alcohol-based resin through an adhesive, and laminating a cellulose acetate-based film on the other side via an adhesive, a cellulose acetate-based film The moisture content before lamination is adjusted to 0.5 weight% or more, The manufacturing method of the polarizing plate characterized by the above-mentioned. The method according to claim 2, wherein the cellulose acetate-based film is subjected to an immersion treatment in water and then a drying treatment before lamination, and the moisture content is adjusted to 0.5% by weight or more. The film according to claim 3, wherein the immersion treatment of the cellulose acetate-based film in water is performed at 10 to 45 DEG C for 1 to 60 seconds, and then the drying treatment is performed at a temperature of 40 to 60 DEG C for 20 to 60 seconds. The method performed on condition that water content in water will be 0.5 weight% or more.

Images