KR20040086570A - Polarizer and method for producing the polarizer - Google Patents

Abstract

PURPOSE: A polarizing plate having a protective layer and a fabricating method thereof are provided to reduce the manufacturing cost by using a simple method without using an organic solvent. CONSTITUTION: A polarizing film(1) is formed with a polyvinyl alcohol-based resin film. A release film(2) is laminated on one side of the polarizing film through a protective layer. The protective layer is formed with a water-soluble coating formation material. In addition, the release film is laminated on both sides of the polarizing film through the protective layer. In addition, the release film is adhered on one side of the polarizing film the protective layer and a protective film is adhered on the other side of the polarizing film by using an adhesive.

Description

Polarizer and its manufacturing method {POLARIZER AND METHOD FOR PRODUCING THE POLARIZER}

This invention relates to the polarizing plate which provided the protective layer in the at least single side | surface of the polarizing film which consists of polyvinyl alcohol-type resin films, and its manufacturing method.

The polarizing plate is used for the front and back of a liquid crystal cell for the purpose of controlling the vibration direction of light, in order to visualize the display pattern of a liquid crystal display device. Generally, the polarizing plate which is widely used is a transparent resin film, especially a tree, on both surfaces of the polarizing film which adsorb | sucked and uniaxially stretched a divinyl pigment | dye to a polyvinyl alcohol-type resin film, and orientated the dichroic dye, through an adhesive layer. It is a structure which laminated | stacked the cellulose acetate type film represented by acetyl cellulose. This is bonded to the liquid crystal cell with a pressure-sensitive adhesive through another optical film as necessary to form a liquid crystal display device.

On the other hand, as liquid crystal display devices are used in various places, for example, thinner and lighter weights are desired for liquid crystal display devices such as mobile applications, and thinner and lighter weights are also desired for polarizing plates used therein.

However, in the polarizing plate of the conventional structure, there is a limit in pursuing thinning and tendency. Although the polyvinyl alcohol polarizing film mentioned above has polarization performance by itself, it is essential to provide a protective layer for the reason of being easy to tear in a processing direction (stretching direction). However, in the method of bonding the transparent resin film through the adhesive layer, there is a limit to the thinning of the transparent resin film in terms of handleability during work. In addition, two layers are required as the adhesive layer and the transparent resin film layer, and there is a problem that it is difficult to realize the purpose of thinning and weight reduction.

For all such problems, a polarizing plate having a urethane prepolymer applied to a polarizing film and forming a coating film layer has been proposed. For example, JP-A-10-221524 (Patent Document 1) describes a polarizing plate in which a urethane prepolymer is applied to at least one side of a polarizing film having a water content of 8% by weight or more to form a coating layer. Moreover, Unexamined-Japanese-Patent No. 11-30715 (patent document 2) describes the polarizing plate which laminated | stacked the urethane resin layer with large storage modulus in 70 degreeC on at least one side of a polarizing film. Japanese Unexamined Patent Application Publication No. Hei 11-30716 (Patent Document 3) discloses a method for producing a polarizing plate by applying a urethane prepolymer to at least one side of a polarizing film and then curing the product under high temperature and high humidity. However, when a urethane prepolymer is used, there exists a problem that the period required for drying and hardening after the coating is long. In addition, since the organic solvent is used for the dilution in the urethane prepolymer, there is a problem in the environment and health of workers. Moreover, when this method is applied to the polarizing plate manufacturing equipment which does not use the conventional organic solvent, facility improvement, such as establishment of explosion-proof equipment, is complicated.

On the other hand, Unexamined-Japanese-Patent No. 2000-199819 (patent document 4) coats and dries the resin solution by the solvent which does not melt | dissolve at least one surface of the polarizing film which consists of hydrophilic polymers, such as polyvinyl alcohol, By forming a transparent thin film layer, the manufacturing method of the polarizing plate which aimed at thickness reduction is proposed. Examples of the transparent thin film layer include cellulose resins, polycarbonate resins, polyester resins and acrylic resins. However, in this proposal, since an organic solvent is used for the resin solution for forming a transparent thin film layer, there are also environmental problems and worker's health problems. Moreover, when this method is applied to the polarizing plate manufacturing equipment which does not use the conventional organic solvent, facility modification, such as new construction of explosion-proof installation, is also complicated.

Attempts have been made to form the protective film of the polarizing plate with resins other than cellulose acetate. For example, Unexamined-Japanese-Patent No. 8-271733 (patent document 5) is a front-side protective film of the polarizing plate arrange | positioned at the front side (visual side) of a liquid crystal cell, On one side of a biaxially stretched polyester film, It is proposed to use a laminated sheet in which a thin layer of polyvinyl alcohol-based resin is formed through an aqueous anchor coating layer.

Moreover, since the adhesive force with the polyvinyl alcohol-type resin which comprises a polarizing film, such as triacetyl cellulose generally used as a protective film of a polarizing plate is not so high, it usually saponifies the surface, Although it is provided for lamination to an optical film, there is an attempt to omit this saponification process. For example, Japanese Unexamined Patent Publication No. 2002-328230 (Patent Document 6) forms a gelatinous coating layer on the surface to be bonded to the polarizing film of the transparent protective film, and laminates it on the polarizing film via the adhesive layer on the gelatinous coating layer side. It is proposed to do it.

Furthermore, various examination is made also about the adhesive layer which bonds a polarizing film and a transparent protective film. For example, Japanese Unexamined Patent Application Publication No. 7-134212 (Patent Document 7) discloses blending a predetermined amount of glyoxal in a polyvinyl alcohol-based adhesive bonding a polyvinyl alcohol-based polarizing film and a protective film. In Patent Publication No. Hei 9-258023 (Patent Document 8), it is described that a predetermined amount of a water-soluble epoxy compound is blended in a polyvinyl alcohol adhesive that bonds a polyvinyl alcohol polarizing film and a protective film.

[Patent Document 1] Japanese Unexamined Patent Publication No. Hei 10-221524

[Patent Document 2] Japanese Patent Application Laid-Open No. 11-30715

[Patent Document 3] Japanese Patent Application Laid-Open No. 11-30716

[Patent Document 4] Japanese Unexamined Patent Publication No. 2000-199819

[Patent Document 5] Japanese Patent Application Laid-Open No. 8-271733

[Patent Document 6] Japanese Unexamined Patent Publication No. 2002-328230

[Patent Document 7] Japanese Patent Application Laid-Open No. 7-134212

[Patent Document 8] Japanese Patent Application Laid-Open No. 9-258023

MEANS TO SOLVE THE PROBLEM The present inventors form a thin protective layer substantially without using an organic solvent with respect to the polarizing film which consists of polyvinyl alcohol-type resin, and aims at further thinning and weight reduction of a polarizing plate, and also the conventional cellulose acetate type protective film / polyvinyl In order to discover the polarizing plate which can be manufactured without changing a polarizing plate manufacturing equipment of the structure which consists of an alcohol type polarizing film / cellulose acetate type protective film, it researched and reached this invention.

Accordingly, an object of the present invention is to provide a polarizing plate which can be thinner and lighter than a polarizing plate having a structure consisting of a conventional cellulose acetate protective film / polyvinyl alcohol polarizing film / cellulose acetate protective film, and furthermore, simply It is providing the manufacturing method. Another object of the present invention can be produced by the same equipment as in the case of manufacturing a polarizing plate of the configuration consisting of a conventional cellulose acetate protective film / polyvinyl alcohol polarizing film / cellulose acetate protective film, and thin and thin It is providing the polarizing plate which can be reduced in weight, and furthermore, is manufacturing this polarizing plate by the method applicable to the said installation.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows typically one form which bonds a peeling film to the polarizing film via the coating liquid of a film forming composition.

It is sectional drawing which shows typically another form which bonds a peeling film to the polarizing film through the coating liquid of a film forming composition.

(Description of Major Symbols in the Drawing)

1: polarizing film

2: release film

3: release film or protective film

4: plating solution

5A, 5B: 1 pair roll

MEANS TO SOLVE THE PROBLEM As a result of repeating research in order to solve such a subject, the present inventors showed light adhesiveness with respect to the polarizing film which consists of a polyvinyl alcohol-type resin film, and a polyvinyl alcohol-type resin, but uses the peelable peeling film after that, When both of them are laminated through an aqueous solution of a water-soluble film-forming composition, and the film-forming composition is cured, a polarizing plate having a structure in which the release film is bonded to one or both surfaces of the polarizing film through a cured product of the water-soluble resin composition When the peeling film is obtained and the peeling film is peeled off, the cured layer of the film-forming composition exposed can be prevented from being easily torn in the processing direction, and can be sufficiently thinned while functioning as a protective layer of the polarizing film. It was found that the present invention was reached.

That is, according to this invention, the polarizing plate in which the peeling film is laminated | stacked on the at least single side | surface of the polarizing film which consists of polyvinyl alcohol-type resin films through the protective layer which consists of water-soluble film-forming compositions is provided.

This protective layer and a peeling film can also be provided in the single side | surface of a polarizing film, and can also be provided in both surfaces of a polarizing film. When the release film is laminated only on one side of the polarizing film via the protective layer, the other side of the polarizing film can be provided with a protective film that cannot be peeled off through the adhesive.

As a water-soluble film-forming composition, what has a polyvinyl alcohol-type resin as a main component is used advantageously. It is preferable that the water-soluble film-forming composition which has polyvinyl alcohol-type resin as a main component contains a curable component. Moreover, polyethylene resin and polyester resin can be used as a peeling film.

The said polarizing plate apply | coats the coating liquid of water-soluble film forming composition to at least one surface of the polarizing film and peeling film which consist of a polyvinyl alcohol-type resin film, bonds the said polarizing film and a peeling film from the application surface side, and then It can manufacture advantageously by the method of hardening the apply | coated coating liquid. Thereafter, when the peeling film is peeled off, the cured layer of the film-forming composition is exposed, and this layer becomes a protective layer to obtain a thinner polarizing plate. At this time, as a water-soluble film-forming composition which comprises a coating liquid, what has polyvinyl alcohol-type resin as a main component is used advantageously.

Moreover, the said polarizing plate supplies the polarizing film and peeling film which consist of a polyvinyl alcohol-type resin film so that both may be bonded between a pair of rolls, and is water-soluble film formation property between the polarizing film and peeling film before bonding between rolls. After supplying the coating liquid of a composition and bonding a polarizing film and a peeling film between rolls through this coating liquid layer, it can be wound up and manufactured continuously in a roll shape by the method of hardening a coating liquid layer.

Best Mode for Carrying Out the Invention

Hereinafter, the present invention will be described in detail. In this invention, a peeling film is laminated | stacked on the at least single side | surface of the polarizing film which consists of polyvinyl alcohol-type resin films through the protective layer which consists of water-soluble film-forming compositions, and it is set as a polarizing plate. Specifically, the polarizing film may be one in which a dichroic dye is adsorbed to a uniaxially stretched polyvinyl alcohol-based resin film.

Polyvinyl alcohol-type resin which comprises a polarizing film is obtained by soaping 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, olefins, vinyl ethers, unsaturated sulfonic acids, 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. This polyvinyl alcohol-based resin may be modified again. For example, polyvinyl formal, polyvinyl acetal, etc. modified with aldehydes may be used. Moreover, the polymerization degree of polyvinyl alcohol-type resin is about 1,000-10,000 normally, Preferably it is about 1,500-5,000.

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 a film by a well-known method. Although the film thickness of the raw film which consists of polyvinyl alcohol-type resin is not specifically limited, For example, it is about 1 micrometer-150 micrometers. Considering the easiness of stretching, the film thickness is preferably 10 µm or more. As a polyvinyl alcohol raw film suitable for a polarizing film, for example, the vinylon film "VF-PS # 7500" (thickness about 75 micrometers) and "VF-PS # 4200" sold by Kuraray Co., Ltd. (thickness about) 42 μm) and the like.

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 the aqueous solution of boric acid, and the process of washing with water after the process by this aqueous solution of boric acid.

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 during boric acid treatment. Of course, uniaxial stretching can also be performed in these multiple steps. In uniaxial stretching, you may extend | stretch uniaxially between the rolls from which a circumferential speed differs, and you may extend | stretch uniaxially using a thermal roll. In addition, dry stretching may be performed in the air, or wet stretching may be performed in a swelled state with a solvent. The draw ratio is usually about 4 to 8 times.

In order to dye a polyvinyl alcohol-type resin film with a dichroic dye, what is necessary is just to immerse a polyvinyl alcohol-type resin film in the aqueous solution containing a dichroic dye. Specifically as an dichroic dye, iodine or a dichroic dye is used. In addition, the polyvinyl alcohol-based resin film is preferably subjected to immersion treatment in water or hot water before 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) 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 a polyvinyl alcohol-type resin film in the aqueous solution containing a water-soluble dichroic dye, and using it is usually adopted. The content of the dichroic dye in this aqueous solution is the water weight per 100 parts by weight normally 1 × 10 ^-3 ~10 parts by weight, preferably from 1 × 10 ^-3 ~1 parts by weight, and, for example, 1 × 10 ^{- 2} parts by weight or less may be sufficient. This aqueous solution may contain inorganic salts such as sodium sulfate as a dyeing aid. 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 30-300 second normally.

The boric acid treatment after dyeing with a dichroic dye is performed by immersing the dyed vinyl alcohol-based resin film in a 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 40 parts by weight or less, preferably 30 parts by weight or less 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.

The polyvinyl alcohol-based resin film after boric acid treatment is usually washed with water. The water washing treatment is performed by immersing the polyvinyl alcohol-based resin film treated with boric acid in water, for example. After washing with water, drying treatment is performed to obtain a polarizing film. The temperature of water in a water washing process is about 5-40 degreeC normally, and immersion time is about 1-120 second normally. The drying treatment performed thereafter is usually carried out using a hot air dryer or a far infrared heater. The temperature of a drying process is about 40-100 degreeC normally. The drying time is usually about 60 to 600 seconds, preferably about 120 to 600 seconds.

The polarizing film obtained in this way is laminated | stacked a peeling film on the at least single side | surface through a protective layer, and turns into a polarizing plate with a peeling film. Thus, by laminating | stacking a peeling film on the outer side of a protective layer, the adhesion of a scratch on the surface of a protective layer can be prevented, and the mixing of a foreign material with a protective layer can be prevented. At this time, a peeling film may be laminated | stacked on both surfaces of a polarizing film through a protective layer, and a peeling film may be laminated | stacked on the single side | surface of a polarizing film through a protective layer. When the release film is laminated only on one side of the polarizing film through the protective layer, the other side of the polarizing film may be exposed as it is, but, for example, a cellulose resin such as triacetyl cellulose or the like through a adhesive in the same manner as a general polarizing plate, It can also be set as the structure which laminated | stacked the non-peelable protective film which consists of transparent resins represented by norbornene-type resin, polycarbonate resin, acrylic resin, etc. The impossibility of peeling here means that even if it is going to peel, a protective film or a polarizing film will generate | occur | produce material destruction and a protective film cannot be peeled off as it is from an adhesive bond layer or a polarizing film as it is.

The protective layer formed on at least one side of the polarizing film is obtained by curing the water-soluble film-forming composition. The water-soluble film forming composition which forms this protective layer should just be a thing which can form the film with favorable adhesiveness with the polyvinyl alcohol-type resin which comprises a polarizing film, For example, polyvinyl alcohol-type resin, polyamide polyamine-type resin What is necessary is just to select and use a water-soluble thing from epoxy resin, melamine resin, urea resin, polyamide resin, polysaccharide, etc. These can be used individually, respectively, and can also be used in combination of multiple.

Polyvinyl alcohol-based resins and polysaccharides are water soluble in most cases. The polyamide polyamine-based resin is obtained by, for example, a reaction of a polyalkylene polyamine such as diethylenetriamine or triethylenetetramine with a dicarboxylic acid such as adipic acid, which is also water-soluble in most cases. As water-soluble epoxy resin, polyamide polyamine epoxy resin etc. which are obtained by making epichlorohydrin react with the above polyamide polyamine, for example are mentioned. As water-soluble melamine type resin, what is obtained by condensation reaction of oligomethylolmelamine like trimethylolmelamine, for example is mentioned. As water-soluble free-form resin, what is obtained by the condensation reaction of urea and formaldehyde is mentioned, for example. As water-soluble polyamide resin, casein, glue, etc. are mentioned, for example.

Among these water-soluble film-forming substances, it is preferable to have a polyvinyl alcohol-based resin, which is the same kind as the resin constituting the polarizing film, from the design of the protective layer laying apparatus, the design of the drying furnace, and environmental problems. The polyvinyl alcohol-based resin is modified such as acetoacetyl group-modified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, methylol group-modified polyvinyl alcohol, amino group-modified polyvinyl alcohol, in addition to partially saponified polyvinyl alcohol and fully saponified polyvinyl alcohol. Polyvinyl alcohol-based resin may be used.

The polyvinyl alcohol-based resin includes a curable component such as water-soluble epoxy resin, dialdehyde such as glyoxal, isocyanate, iron ions, cobalt ions, nickel ions, copper ions, zinc ions, aluminum ions, and metal ions such as zirconium ions. It is preferable to mix | blend a crosslinking agent. The water-soluble epoxy resin may be, for example, a polyamide polyamine epoxy resin obtained by reacting epichlorohydrin with a polyamide polyamine which is a reaction product of a polyalkylene polyamine and a dicarboxylic acid as described above, and such a polyamide polyamine Commercially available products of epoxy resins include "Sumirez resin 650", "Sumirez resin 675" sold by Sumitomo Chemical Co., Ltd., and "WS-525" sold by Nippon PMC. When it contains such a curable component, the quantity is about 1-50 weight part per 100 weight part of polyvinyl alcohol-type resins which comprise a film forming composition.

What is necessary is just to apply | coat and harden the coating liquid containing this composition, in order to form a protective layer from the water-soluble film-forming composition mentioned above. The coating solution used for this purpose is obtained by dissolving a film-forming composition in a solvent. As a solvent at this time, water is used, but a small amount of hydrophilic organic solvent, for example, alcohols, may be contained. Moreover, the stabilizer etc. for dissolving solute stably may be contained.

When laminating a peeling film through the protective layer which consists of a water-soluble film forming composition on the surface of a polarizing film, the coating liquid of the water-soluble film forming composition mentioned above is apply | coated to at least one surface of a polarizing film and a peeling film, What is necessary is just to bond a polarizing film and a peeling film at the application surface side, and to dry and harden the apply | coated coating liquid then.

The method of coating the coating liquid of the film-forming composition on the surface of the polarizing film or the peeling film may be generally known in general. For example, the casting method, the meyer bar coating method, the gravure coating method, the die coating method, and the dip coating method And a spraying method. A casting method is a method of flowing and spreading a coating liquid on the surface, moving a polarizing film or a peeling film which is a to-be-coated object in a substantially vertical direction, a substantially horizontal direction, or the inclination direction between both. After apply | coating a coating liquid, when thinking about bonding a polarizing film and a peeling film, the method of casting a coating liquid between a polarizing film and a peeling film is employ | adopted preferably.

When supplying a polarizing film and a peeling film in continuous film form, respectively and winding up in a film form after lamination | stacking, as shown in FIG. 1, a pair of rolls 5A of a polarizing film 1 and the peeling film 2 are shown. , 5B) is supplied at a predetermined speed so that the coating liquid 4 for forming the protective layer is cast between the polarizing film 1 and the release film 2, and then the coating layer is polarized film. The method of sandwiching between (1) and the peeling film 2 and passing the pair of rolls 5A and 5B is preferable. By employing such a method, the protective layer after hardening can also be made uniform thickness. In FIG. 1, the product after lamination progresses in the direction of a white arrow. Moreover, a pair of roll 5A, 5B is rotating in the arrow direction, respectively. Moreover, the linear pressure by a pair of roll 5A, 5B can be arbitrarily adjusted so that a film forming composition can form a fixed coating layer. Although the state which made the coating liquid 4 fall on the surface of the polarizing film 1 is shown in FIG. 1, even if it makes the coating liquid 4 fall on the surface of the peeling film 2, the same thing can be obtained.

The peeling film laminated | stacked on the surface of a polarizing film through a protective layer protects the surface of the polarizing plate, and peels off before use, until a polarizing plate is actually used. This peeling film may be suitably adhesive enough so that it may peel easily before use of a polarizing plate, and what is necessary is not to inhibit drying and hardening of a protective layer. Specifically, for example, a film made of polyethylene resin or a film made of polyester resin is generally used. It is advantageous that the thickness of the release film is, for example, 30 µm or more. In order to prevent curling of a polarizing plate, it is preferable to use a thick peeling film, for example, using a peeling film of about 75 micrometers thick, or adding a 75 micrometers thick film to a 38 micrometers thick peeling film. To form a release film or to use a release film having a thickness of about 125 µm.

Moreover, in order to adjust the adhesiveness and peelability of a peeling film suitably, the surface bonded to a polarizing film may be surface-treated, such as a plasma process, a corona treatment, an ultraviolet irradiation process, a frame treatment, or adheres to the surface. A layer, a silicone fluorine-type mold release agent layer, surfactant, etc. may be provided suitably. It is preferable that this peeling film is further subjected to an antistatic treatment in order to prevent adhesion of dust on the surface, and the surface resistance value is 10 ¹³ Ω /? Or less, in particular 10 ¹⁰ Ω /? It is preferable that it is the following.

When laminating a peeling film through the coating liquid of the water-soluble film-forming composition used as a protective layer on both surfaces of a polarizing film, after laminating the peeling film 2 to the single side | surface of the polarizing film 1 by the method of FIG. The other peeling film can be laminated | stacked on the other surface of the polarizing film 1 by the same method, and as shown in FIG. 2, the water-soluble film which becomes a protective layer simultaneously on both surfaces of the polarizing film 1 The form which laminates the peeling films 2 and 3 via the coating liquids 4 and 4 of a formation composition can also be employ | adopted. That is, in FIG. 2, it is supplied at a predetermined speed so that the polarizing film 1 and the peeling films 2 and 3 may be bonded between the pair of rolls 5A and 5B rotated in the direction of the arrow on both sides thereof, respectively. The coating liquids 4 and 4 for forming a protective layer are respectively cast between the polarizing film 1 and the 1st peeling film 2, and between the polarizing film 1 and the 2nd peeling film 3, Thereafter, each coating layer is sandwiched between the polarizing film 1 and the release films 2 and 3 on both sides thereof, and passes through a pair of rolls 5A and 5B to advance in the direction of the white arrow.

When laminating | stacking a peeling film on the single side | surface of a polarizing film through a protective layer, and laminating | stacking the protective film which is not peelable on the other surface of a polarizing film, it supplies to one surface of the polarizing film 1 in FIG. What is necessary is just to make the film 2 used as a peeling film, and to make the film 3 supplied to the other surface into a protective film. As the protective film 3 in this case, the film which consists of resin of cellulose acetate type, such as a triacetyl cellulose and a diacetyl cellulose, especially a triacetyl cellulose film is used suitably. Since the cellulose acetate-based resin does not necessarily have sufficient adhesive strength to the polyvinyl alcohol-based resin as described above, it is preferable to perform saponification treatment on the bonding surface. As a protective film, the thing of thickness 100 micrometers or less is used normally, Preferably it is 60 micrometers or less, More preferably, it is 50 micrometers or less. For example, "Fujitaek T40UZ" (about 40 micrometers in thickness), "Fujitaek SH50" (about 50 micrometers in thickness), etc. which are sold from Fuji Photo Film Co., Ltd. are used suitably. The surface (exposed surface) on the opposite side to the bonding surface of the protective film may be subjected to appropriate surface treatment such as antiglare treatment, hard coating treatment, antireflection treatment, antistatic treatment and the like.

Moreover, in this case, the adhesive agent which bonds the polarizing film 1 and the protective film 3 may be the same as the film forming composition for forming a protective layer between the peeling film 2, and It may be of different composition. For example, polyvinyl chloride is used as an adhesive for bonding a protective film using an aqueous solution containing a curable component together with a polyvinyl alcohol-based resin as a film-forming composition for forming a protective layer between the release film 2. It is also possible to use an aqueous solution of alcohol only.

After laminating | stacking a polarizing film and a peeling film through the coating liquid which forms a protective layer, this coating liquid is hardened. When using as a film forming composition for forming a protective layer the thing which has polyvinyl alcohol-type resin as a main component, hardening is performed by thermosetting, ultraviolet curing, or dry curing. For example, dry hardening is performed by blowing hot air, and the temperature at this time is suitably selected in the range of about 40-100 degreeC, Preferably it is 45-90 degreeC. The dry curing time is usually about 20 to 1,200 seconds. Thermal curing or ultraviolet curing may be performed after drying. The thickness of the protective layer after hardening is about 0.1-10 micrometers normally, Preferably it is 0.2 micrometer or more, More preferably, it is 0.5 micrometer or more, More preferably, it is 5 micrometers or less.

When the protective film which cannot be peeled off is laminated on one side of the polarizing film, the surface of the protective film may then be appropriately subjected to surface treatment such as an antiglare treatment, a hard coat treatment, an antireflection treatment, an antistatic treatment and the like. When performing such surface treatment, it is preferable to thicken the peeling film of the opposite surface, or to laminate | stack a film in order to prevent the polarization plate from collapsing. For example, an appropriate form is selected, for example, using a 75 μm thick release film, or laminating a film having a thickness of 75 μm to a 38 μm thick release film.

You may adhere | attach an optical functional film to the surface of a protective layer through an adhesive agent. As an optical functional film, the liquid crystal compound is apply | coated to the surface of a base material, for example, the reflective type polarizing film which permeate | transmits the oriented optical compensation film and the predetermined kind of polarized light, and reflects the polarized light which has the opposite property to it. , Retardation film made of polycarbonate resin, retardation film made of cyclic polyolefin resin, film with anti-glare function having irregular shape on the surface, film with antireflection treatment on surface, reflective film with reflection function on surface, reflection function and transmission And translucent reflective films having a function. As a commercial item corresponding to the optical compensation film in which the liquid crystalline compound is coated on the surface of the substrate and is oriented, "WV film" sold by Fuji Photo Film Co., Ltd. and "NH film sold by Shin Nippon Petroleum Co., Ltd." "And" NR film "(both trade names). As a commercial item which corresponds to the reflection type polarizing film which permeate | transmits a predetermined kind of polarized light and reflects the polarized light which has the opposite property, it is Minnesota Mining and Manufacturing Co., Ltd. (3M company) (Sumitomos Rem Co., Ltd. in Japan) ) And "DBEF" (trade name). Moreover, as a commercial item corresponding to the phase wave film which consists of cyclic polyolefin resin, "S thinner" sold by Sekisui Chemical Co., Ltd., "Zenooa film" (all brand name) sold by OPTES, etc. There is this.

Example

The present invention will be described in more detail with reference to the following Examples, which however are not intended to limit the present invention. In the examples,% and parts indicating content to the amount of use are based on weight unless otherwise specified.

Reference Example 1

A polyvinyl alcohol film having an average degree of polymerization of about 2,400 and a degree of saponification of at least 99.9 mol% and a thickness of 75 µm was uniaxially stretched by 5 times in magnification by dryness, and immersed in pure water at 60 ° C. for 1 minute while maintaining tension again. Subsequently, it was immersed in 28 degreeC for 35 second in the aqueous solution which weight ratio of iodine / potassium iodide / water is 0.15 / 5/100. Thereafter, potassium iodide / boric acid / water was immersed in an aqueous solution having a weight ratio of 9 / 9.5 / 100 for 300 seconds at 76 ° C. Subsequently, the mixture was washed with pure water at 15 ° C. for 2 seconds, and then dried at 50 ° C. to obtain a polarizing film in which iodine was adsorbed to polyvinyl alcohol. Table 1 shows the thickness of this polarizing film. The polarizing film in this state lifted one side part orthogonal to a drawing direction with both hands, and when it applied the force in the opposite direction with each hand, it was torn easily in the extending direction.

Reference Example 2

The same polyvinyl alcohol film as that used in Reference Example 1 was subjected to uniaxial stretching and dipping treatment for pure water in the same manner, followed by 300 seconds at 70 ° C. in an aqueous solution having a dichroic dye / sodium sulfate / water weight ratio of 0.025 / 2/100. It was immersed and dyed and then immersed in an aqueous solution of boric acid / water in a weight ratio of 7.5 / 100 for 300 seconds at 73 ° C. Thereafter, water washing and drying were performed in the same manner as in Reference Example 1 to obtain a polarizing film in which dichroic dyes were adsorbed and aligned on polyvinyl alcohol. Table 1 shows the thickness of this polarizing film. The polarizing film in this state also lifted one side part orthogonal to an extending | stretching direction with both hands, and when it applied the force in the opposite direction with each hand, it was torn easily in the extending | stretching direction.

Example 1

3 parts of polyvinyl alcohol-type resin [KL-318 of Kuraray Co., Ltd., saponification degree 87.8 mol%] is melt | dissolved with respect to 100 parts of water, and water-soluble polyamide epoxy resin [Sumitomo Chemical Co., Ltd. ( 1.5 parts of "Sumirez resin 650" made from the Co., Ltd. product, and solid content concentration 30% were added, and it was set as the polyvinyl alcohol-type coating liquid. The polyvinyl alcohol-based coating liquid was cast on both surfaces thereof while the polarizing film obtained by the method of Reference Example 1 was moved in a vertical direction under an atmosphere of 23 ° C., and the thickness of one side was released on the coated surface (both sides). A polyethylene terephthalate film (" 38EAS " manufactured by Fujimori Industrial Co., Ltd.) having a thickness of about 38 µm is bonded and sandwiched from the release treatment surface, passed through a pair of rolls, and then hot-air dried at 60 캜 for 5 minutes to cure. And the polarizing plate with a double-sided peeling film was obtained. The manufacture of this polarizing plate with a peeling film was able to be performed using the manufacturing equipment of a conventional polarizing plate. The peeling film of both surfaces was removed from the obtained polarizing plate with release film, and the polarizing plate which has a polyvinyl alcohol-type protective layer on both surfaces was obtained. Table 1 shows the thickness of this polarizing plate. Compared with the polarizing film of Reference Example 1, this polarizing plate was hard to tear even when holding one side part orthogonal to a drawing direction with both hands and applying a force in the opposite direction with each hand, and tear resistance was provided by presence of a protective layer.

Example 2

40% glyoxal aqueous solution [obtained from Wako Pure Chemical Industries, Ltd.] 20% aqueous solution of polyvinyl alcohol ["PVA 117H" of Kuraray Co., Ltd., polymerization degree 1,700, saponification degree 99.3 mol% or more] 20 Part and 2.5 parts of zinc chloride were added to obtain a polyvinyl alcohol-based coating liquid. Using the polarizing film obtained by the method of this coating liquid and the reference example 2, the polarizing plate with a double-sided peeling film was produced by the method similar to Example 1. The manufacture of this polarizing plate with a peeling film was also able to be performed using the manufacturing equipment of a conventional polarizing plate. The peeling film of both surfaces was removed from the obtained polarizing plate with release film, and the polarizing plate which has a polyvinyl alcohol-type protective layer on both surfaces was obtained. Table 1 shows the thickness of this polarizing plate. Compared with the polarizing film of Reference Example 2, this polarizing plate was hard to tear even when holding one side portion orthogonal to the stretching direction with a force applied in the opposite direction with each hand, and tear resistance was given by the presence of the protective layer.

Reference Example 3

A polyvinyl alcohol film having an average degree of polymerization of about 2,400 and a saponification degree of 99.9 mol% or more and a thickness of 75 μm was uniaxially stretched by 5 times in magnification by dryness, and immersed in pure water at 60 ° C. while maintaining tension again. Next, it was immersed at 28 degreeC in the aqueous solution which weight ratio of iodine / potassium iodide / water is 0.15 / 5/100. Thereafter, potassium iodide / boric acid / water was immersed in an aqueous solution of 9 / 8.1 / 100 by weight ratio at 69 ° C. for 180 seconds. Subsequently, after wash | cleaning with the pure water of 25 degreeC, it dried at 60 degreeC and obtained the polarizing film by which the iodine adsorption orientation was carried out to polyvinyl alcohol.

Example 3

While moving the polarizing film obtained in Reference Example 3 in an inclined direction under an atmosphere of 23 ° C., a polyethylene terephthalate film (“38EAS” manufactured by Fujimori Industries, Ltd.) having a thickness of about 38 μm on which one side was released was peeled off. It is made into a film, and it is supplied so that the mold release process surface may be a polarizing film side, and the lower surface of a polarizing film carries a saponification-treated triacetyl cellulose film ("Fuji-Tak T40UZ" by Fuji Photo Film Co., Ltd.). It was supplied as. And between a polarizing film and a peeling film, and between a polarizing film and a protective film, a pair of rolls are made to pass the polyvinyl alcohol-type coating liquid of the composition same as used in Example 1, flexibly, and it is 60 minutes after that for 5 minutes. It was dried by hot air and cured to obtain a polarizing plate with a single side release film. The manufacture of this polarizing plate with a peeling film was able to be performed using the manufacturing equipment of a conventional polarizing plate. The peeling film of one side was removed from the obtained polarizing plate with a peeling film, and the polarizing plate which has the polyvinyl alcohol-type protective layer on one side, and the protective film which is not peelable on the other side was obtained. Table 1 shows the thickness of this polarizing plate. Compared with the polarizing film of Reference Example 1, this polarizing plate was difficult to be torn even when holding one side portion orthogonal to the stretching direction with both hands and applying a force in the opposite direction with each hand.

Comparative Example 1

Polyvinyl alcohol-based coating liquid used in Example 1 on both sides of the polarizing film obtained by the method of Reference Example 1 was flexible in the same manner as in Example 1, and on the coated surface (both sides), one-sided saponification tree having a thickness of about 80 μm. An acetyl cellulose film ("Fuji-Tak T80UZ" manufactured by Fuji Photo Film Co., Ltd.) was bonded to the saponification treatment surface, sandwiched, and passed through a pair of rolls, followed by hot air drying at 60 캜 for 5 minutes, followed by curing. The protective film (triacetyl cellulose layer) of this polarizing plate produced the material destruction and was unable to peel, even if it tried to remove the protective film (triacetylcellulose layer) of this polarizing plate.

Comparative Example 2

On both sides of the polarizing film obtained by the method of Reference Example 2, the polyvinyl alcohol-based coating liquid used in Example 2 was cast in the same manner as in Example 2, and again, the single-sided saponification tree having a thickness of about 80 μm on the coated surface (both sides). Acetyl cellulose film ["Fuji-Taek UV-80" manufactured by Fuji Photo Film Co., Ltd.) was bonded to the saponification surface, pasted through a pair of rolls, and then cured by hot air drying at 60 캜 for 5 minutes. And the polarizing plate with a double-sided protective film were produced. Even if it tried to remove the protective film (triacetyl cellulose layer) of this polarizing plate, a protective film or a polarizing film caused material destruction, and was not peelable. Table 1 shows the thickness of this polarizing plate.

Yes Reference Example Example Comparative example One 2 One 2 3 One 2 thickness 22.1 μm 22.1 μm 22.8 ㎛ 27.6㎛ 62.8 ㎛ 183.9 ㎛ 185.7 μm

According to the present invention, a thin and lightweight polarizing plate is provided, which contributes to the thinning of the liquid crystal display device. This polarizing plate does not need to use an organic solvent at the time of manufacture, and is excellent in environmental and safety hygiene, and can be manufactured with the same equipment as a polarizing plate made of a conventional transparent protective film / polarizing film / transparent protective film. There is no need for big facility investment. Moreover, according to the manufacturing method of this invention, such a polarizing plate can be manufactured simply.

Claims (10)

A peeling film is laminated | stacked on the at least single side | surface of the polarizing film which consists of polyvinyl alcohol-type resin films through the protective layer which consists of water-soluble film-forming compositions. The polarizing plate of Claim 1 by which the peeling film is laminated | stacked on both surfaces of a polarizing film through this protective layer. The polarizing plate of Claim 1 in which the peeling film is laminated | stacked on the single side | surface of a polarizing film through this protective layer, and the protective film which cannot be peeled off via an adhesive agent is laminated on the other surface of the polarizing film. The polarizing plate according to any one of claims 1 to 3, wherein the water-soluble film-forming composition has a polyvinyl alcohol-based resin as a main component. The polarizing plate according to claim 4, wherein the water-soluble film-forming composition containing polyvinyl alcohol-based resin as a main component contains a curable component. The polarizing plate according to any one of claims 1 to 5, wherein the polarizing film is made of polyethylene resin or polyester resin. The coating liquid of a water-soluble film-forming composition is apply | coated to at least one surface among the polarizing film which consists of a polyvinyl alcohol-type resin film, and the peeling film laminated | stacked on the surface, and the said polarizing film and a peeling film are made from the application surface side. Bonding and then hardening the apply | coated coating liquid, The manufacturing method of the polarizing plate characterized by the above-mentioned. The method according to claim 7, wherein after the curing of the coating liquid, the release film is peeled off to expose the protective layer. The method according to claim 7 or 8, wherein the water-soluble film-forming composition contains polyvinyl alcohol-based resin as a main component. A water-soluble film between the polarizing film and the peeling film before supplying the polarizing film which consists of a polyvinyl alcohol-type resin film, and the peeling film laminated | stacked on the surface so that both may be bonded between a pair of rolls, and bonding between rolls. The coating liquid of a formation composition is supplied, and after bonding a polarizing film and a peeling film between rolls through this coating layer, the coating layer is hardened, The manufacturing method of the polarizing plate characterized by the above-mentioned.