KR20190143024A - Polarizing plate, adhesive for the same and optical display apparatus comprising the same - Google Patents

Abstract

The present invention provides a polarizing plate, adhesive for the polarizing plate therefore, and an optical display device including the same. The polarizing plate includes: a polarizer; a first protective layer which is laminated by the adhesive for the polarizing plate on one surface of the polarizer; and a second protective layer which is laminated on the other surface of the polarizer. An adhesive layer for the polarizing plate is formed of an adhesive for a polarizing plate including polyvinyl alcohol-based resin, an imine crosslinking agent, and amino formaldehyde-based resin. The first protective layer includes a protective film having a moisture permeability of 300 g/m^2 per day or more. The polarizing plate was left in water at 44°C for 12 hours and then the total area of bubbles formed between the polarizer and the first protective layer was equal to or less than 10 (mm)^2 per unit area 100 (mm)^2 of the polarizing plate. The present invention is able to improve processability.

Description

POLARIZING PLATE, ADHESIVE FOR THE SAME AND OPTICAL DISPLAY APPARATUS COMPRISING THE SAME}

The present invention relates to a polarizing plate, an adhesive for a polarizing plate, and an optical display device including the same.

The liquid crystal display device includes a liquid crystal panel and a polarizing plate attached to both surfaces of the liquid crystal panel. The polarizing plate includes a polarizer and a protective film formed on one or both surfaces of the polarizer to protect the polarizer. The polarizer and the protective film are adhered by an adhesive layer for polarizing plates formed of an adhesive for polarizing plates.

As the protective film, a cellulose-based protective film represented by triacetyl cellulose may be used. The cellulose-based protective film has a higher water permeability than a cyclic olefin polymer film including a polyester film including an polyethylene terephthalate, an acrylic film, a cyclic olefin polymer, a norbornene system, and the like. Therefore, the cellulose-based protective film can improve the reliability of the polarizing plate by easily releasing moisture, bubbles, etc. which may occur in the polarizing plate adhesive and / or the polarizer through the first protective layer when left for a long time at high temperature and high humidity of the polarizing plate. have.

However, since the cellulose-based protective film has high water permeability, when the polarizing plate is immersed in warm water, external moisture easily penetrates into the polarizing plate, and blisters are easily generated between the polarizer and the protective film. Although the crosslinking agent content of the polarizing plate adhesive may be increased, the degree of crosslinking of the adhesive layer may be increased, but the gelation time of the adhesive may be shortened, resulting in a poor manufacturing process of the polarizing plate.

Background art of the present invention is described in Japanese Patent Laid-Open No. 2015-010192.

An object of the present invention is to provide a polarizing plate that can suppress the generation of blisters between the polarizer and the protective layer even during hot water immersion.

Another object of the present invention is to provide a polarizing plate having excellent polarizing plate manufacturing processability.

Still another object of the present invention is to provide a polarizing plate having excellent adhesion even when submerged.

Still another object of the present invention is to provide an adhesive for a polarizing plate which can improve processability in manufacturing a polarizing plate due to a long gelling time and can suppress blister generation between the polarizer and a protective layer even when immersed in warm water.

Polarizing plate of the present invention is a polarizer; A first protective layer laminated on one surface of the polarizer by an adhesive layer for polarizing plates; And a second protective layer laminated on the other surface of the polarizer, wherein the adhesive layer for the polarizing plate is formed of an adhesive for a polarizing plate including a polyvinyl alcohol-based resin, an imine-type crosslinking agent, and an amino formaldehyde-based resin, and the first protective layer. The layer includes a protective film having a moisture permeability of 300 g / m ² or more, and the polarizing plate is left in water at 44 ° C. for 12 hours, and then the total area of the blister formed between the polarizer and the first protective layer is the polarizing plate. It may be 10 (mm) ² or less per unit area 100 (mm) ² .

The adhesive for polarizing plates of this invention contains polyvinyl alcohol-type resin, an imine crosslinking agent, and amino formaldehyde-type resin, and can gelatinize 4 hours or more.

The optical display device of the present invention may include the polarizing plate of the present invention.

The present invention provides a polarizing plate capable of suppressing blister generation between the polarizer and the protective layer even when immersed in hot water.

The present invention provides a polarizing plate having excellent polarizing plate manufacturing processability.

The present invention provides a polarizing plate excellent in adhesion even upon immersion.

The present invention provides a polarizing plate adhesive which can improve the processability in manufacturing a polarizing plate due to a long gelling time and can suppress blister generation between the polarizer and the protective layer even when immersed in warm water.

1 is a cross-sectional view of a polarizer of an embodiment of the present invention.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. The drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification.

In the present specification, "upper" and "lower" are based on the drawings and are not necessarily fixed to upper and lower parts, and "upper" to "lower" and "lower" to "upper" according to the viewing time. Can be.

In the present specification, the "moisture permeability" of the protective film is a value measured at 40 ° C. and 90% relative humidity according to KS A1013 standard.

The "pKa" of an acid herein is the value measured by the conventional method at 25 degreeC.

In the present specification, the "bubble" has a predetermined cross-sectional area when water is introduced into an arbitrary point of the adhesive layer from the first protective layer to the polarizer so that the first protective layer swells in the shape of a convex lens. Can be defined as a drop of water.

Specifically, the "bubble" may be formed in at least one of the first protective layer and the adhesive layer for the polarizing plate, inside the adhesive layer for the polarizing plate, between the polarizer and the adhesive layer for the polarizing plate.

As used herein, the term "gelling time" refers to a time for starting the portion where the adhesive does not flow when 10 ml of the adhesive is placed in a 15 ml transparent vial container and then the upper and lower sides of the container are turned over. Can be defined.

The inventor of the present invention comprises a polarizer, a first protective layer laminated on one surface of the polarizer by an adhesive layer for polarizing plates; And a second protective layer laminated on the other surface of the polarizer, wherein the first protective layer comprises a protective film having a water transmittance of 300 g / m ² · day or more, wherein the adhesive layer for the polarizing plate is polyvinyl alcohol. When formed of a polarizing plate adhesive containing an acrylic resin, an imine cross-linking agent, and an amino formaldehyde-based resin, the water resistance evaluation condition in hot water, that is, when the polarizing plate is immersed in warm water, has a small blistering area between the polarizer and the protective film, thereby providing excellent water resistance. And it delayed the gelation time of the adhesive agent for polarizing plates, confirmed that the manufacturing processability of a polarizing plate was also excellent, and completed this invention. Preferably, the first protective layer and the second protective layer may each include a protective film having a moisture permeability of 300 g / m ² · day or more.

Hereinafter, the polarizing plate of one embodiment of the present invention will be described.

Referring to FIG. 1, the polarizer is a polarizer 100, a first protective layer 300 laminated on one surface of the polarizer 100 by an adhesive layer 200 for a polarizer, and a second laminated on the other surface of the polarizer 100. The protective layer 400 may be included.

Adhesive layer for polarizer

The adhesive layer 200 for the polarizer may be formed between the polarizer 100 and the first protective layer 300 to bond the polarizer 100 and the first protective layer 300 to each other.

The polarizing plate adhesive layer 200 may be formed of a polarizing plate adhesive including a polyvinyl alcohol-based resin, an imine crosslinking agent, and an amino formaldehyde-based resin. Therefore, since the moisture permeability of the first protective layer 300 is 300 g / m ² · day or more and the moisture permeability is higher than that of the (meth) acrylic, polyester, cycloolefin, and the like films, the polarizer is used by using a protective film having a poor water resistance. Even in the case of adhering, the water resistance during the warm water immersion of the polarizing plate can be improved, and the gelation time of the adhesive for the polarizing plate is long, so that the processability can be improved during the production of the polarizing plate.

Specifically, the polarizing plate may be left in water at 44 ° C. for 12 hours, and then the total area of the blisters formed between the polarizer and the first protective layer may be 10 (mm) ² or less per unit area 100 (mm) ² of the polarizing plate. The unit area of the polarizing plate is defined as the unit area of the area of the polarizing plate between the polarizer and the first protective layer.

The polyvinyl alcohol-based resin may be excellent in adhesion to the polyvinyl alcohol-based polarizer as a vinyl-based polymer resin. The polyvinyl alcohol-based resin may include at least one of partially saponified polyvinyl alcohol-based resin, fully saponified polyvinyl alcohol-based resin, and modified polyvinyl alcohol-based resin. Modified polyvinyl alcohol-based resin may include at least one of carboxylic acid-modified polyvinyl alcohol-based resin, acetoacetyl group-modified polyvinyl alcohol-based resin, methylol group-modified polyvinyl alcohol-based resin, amino group-modified polyvinyl alcohol-based resin have. Preferably, the acetoacetyl group-modified polyvinyl alcohol-based resin may be preferable because it contains a highly reactive functional group.

The polyvinyl alcohol-based resin is not particularly limited in average polymerization degree and average saponification degree. The polyvinyl alcohol-based resin may have an average polymerization degree of 500 to 5000, preferably 1000 to 2500, and an average saponification degree of 90% to 99.9 mol%, preferably 95 mol% to 98 mol%. It may be excellent in adhesion with the polyvinyl alcohol polarizer in the above range.

The adhesive for polarizing plates may contain an aqueous solvent as a solvent. An aqueous solvent can dissolve a polyvinyl alcohol-type resin, an imine crosslinking agent, and an amino formaldehyde-type resin, and can improve the applicability | paintability of the adhesive agent for polarizing plates. The aqueous solvent may contain water, alcohols, preferably water.

The polyvinyl alcohol resin may be included in an amount of 1 to 10 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of the aqueous solvent. In the above range, it is easy to disperse the polyvinyl alcohol-based resin, the imine-type crosslinking agent, the amino formaldehyde-based resin and the coating property of the adhesive for polarizing plate may be good.

An imine crosslinking agent is included in the adhesive layer for polarizing plates, and can prevent water from penetrating into the side surface of a polarizing plate even in the water resistance evaluation by immersion in hot water, and can improve the water resistance of a polarizing plate. The polarizing plate adhesive containing only amino formaldehyde-based resin in polyvinyl alcohol-based resin without an imine crosslinking agent has a limit in improving water resistance in evaluation of water resistance by immersion in warm water.

Polyethylenimine can be used as an imine crosslinking agent. Polyethyleneimine is included in the combination of polyvinyl alcohol-based resin and amino formaldehyde-based resin to improve the water resistance when evaluating the water resistance by hot water immersion even in a protective film having a high water permeability of 300 g / m ² · day or more.

The imine crosslinking agent may be included in an amount of 0.1 to 20 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the polyvinyl alcohol-based resin. In the above range, water permeation at the side of the polarizing plate can be suppressed to improve water resistance.

The amino formaldehyde-based resin is included in the adhesive layer for polarizing plates, and even in extreme water resistance evaluation, water can be prevented from penetrating into the surface of the polarizing plate, that is, the first protective layer, thereby improving the water resistance of the polarizing plate. Polarizer adhesives containing only imine-type crosslinking agents in polyvinyl alcohol-based resins without amino formaldehyde-based resins have a limit in preventing water bubbles from forming between the polarizer and the protective film by blocking moisture flowing from the surface of the protective film in extreme water resistance evaluation. there was.

The amino formaldehyde-based resin may include one or more of methylol urea, methylol melamine, alkylated methylol urea, alkylated methylolated melamine, acetoguanamine, a condensate of benzoguanamine and formaldehyde. Preferably methylol melamine can be used.

The amino formaldehyde-based resin may be included in 10 parts by weight to 150 parts by weight, preferably 30 parts by weight to 120 parts by weight based on 100 parts by weight of polyvinyl alcohol-based resin. In the above range, it is possible to suppress the water penetration in the side of the polarizing plate to improve the water resistance, the gelation time of the adhesive for the polarizing plate is long, the manufacturing processability of the polarizing plate can be improved.

The adhesive for polarizing plates may further contain one or more additives from stabilizers, such as a coupling agent, such as a silane coupling agent and a titanium coupling agent, a tackifier, a ultraviolet absorber, antioxidant, a heat resistant stabilizer, and a hydrolysis stabilizer.

The adhesive for a polarizing plate may have a gelation time of 4 hours or more, specifically 4 hours to 72 hours. In the above range, the gelation of the adhesive for the polarizing plate is slow so that the processability in manufacturing the polarizing plate can be improved.

In one embodiment, the adhesive for polarizing plates may not comprise a zirconium compound. Even if the adhesive for polarizing plates of the present invention does not contain a zirconium compound, it is possible to suppress blister generation during hot water immersion of the polarizing plate.

In one embodiment, the adhesive for polarizing plates may not include a crosslinking agent (non-amino formaldehyde based crosslinking agent) other than the amino formaldehyde-based resin. Even if the adhesive for polarizing plates of the present invention does not contain a non-amino formaldehyde-based crosslinking agent, it is possible to suppress blister generation during hot water immersion of the polarizing plate.

The adhesive layer 200 for the polarizing plate may have a thickness of 10 nm to 1 μm, specifically 50 nm to 200 nm. In the above range, it can be used for the polarizing plate, the polarizer and the protective film can be bonded without being separated from each other.

First protective layer

The first protective layer 300 may be formed on one surface of the polarizer 100 by the adhesive layer 200 for the polarizer to protect and support the polarizer. The first protective layer 300 is formed in direct contact with the polarizing plate adhesive layer 200 and the polarizer 100, respectively.

The first protective layer 300 may include a protective film having a moisture permeability of 300 g / m ² or more. When the moisture permeability range is left for a long time at high temperature and high humidity of the polarizing plate, water, bubbles, etc., which may occur in the polarizing plate adhesive and / or the polarizer are easily released through the first protective layer, thereby improving reliability of the polarizing plate. have. However, when the moisture permeability of the first protective layer is high, external moisture may easily penetrate into the polarizing plate. According to the present invention, the polarizing plate adhesive layer is formed of an adhesive for a polarizing plate including a polyvinyl alcohol-based resin, an imine crosslinking agent and an amino formaldehyde-based resin, even if the first protective layer includes a protective film having a moisture permeability of 300 g / m ² · day or more. This solved the problem of water resistance during hot water immersion according to high moisture permeability. Preferably, the protective film may have a moisture permeability of 300 g / m ² ㆍ day to 1000 g / m ² ㆍ day, more preferably 300 g / m ² ㆍ day to 500 g / m ² ㆍ day.

The protective film may include an optically transparent resin film having the above-mentioned moisture permeability. Specifically, the protective film may include one or more of a cellulose-based film such as triacetyl cellulose, diacetyl cellulose, and an acrylic film, but is not limited thereto.

The protective film may have a thickness of 10 μm to 100 μm, specifically 20 μm to 80 μm. In the above range, it can be used for the polarizing plate, it can protect the polarizer.

Although not shown in FIG. 1, a functional coating layer may be additionally formed on one surface of the first protective layer 300, that is, the surface opposite to the surface to which the polarizer is bonded. The functional coating layer may provide additional functions to the polarizer. For example, the functional coating layer may include one or more of a primer layer, a hard coating layer, an anti-fingerprint layer, an antireflection layer, an antiglare layer, a low reflection layer, an ultra low reflection layer, but is not limited thereto.

The first protective layer 300 may have a thickness of 10 μm to 100 μm, specifically 20 μm to 80 μm. In the above range, it can be used for the polarizing plate, it can protect the polarizer.

Second protective layer

The second protective layer 400 may be formed on the other surface of the polarizer 100 to protect and support the polarizer.

In one embodiment, the second protective layer has a moisture permeability of at least 300 g / m ² · day, preferably from 300 g / m ² · day to 1000 g / m ² · day, more preferably from 300 g / m ^2. day to 500 g / m ² .

In other embodiments, the second protective layer has a moisture permeability 300g / m ² and day, preferably less than 0g / m ² and day to 200g / m ² and day, more preferably, and a moisture transmission rate 10g / m ² day to 200 g / m ² · day.

The second protective layer 400 may be at least one of a protective film or a protective coating layer.

When the second protective layer 400 is a protective film, the second protective layer may be attached to the polarizer by the adhesive layer for the polarizing plate. The second protective layer and the polarizer are each formed directly on the adhesive layer for the polarizing plate.

The protective film may include an optically transparent resin film having the above-mentioned moisture permeability. Specifically, the protective film is a cyclic olefin including a cellulose-based film such as triacetyl cellulose, diacetyl cellulose, a polyester-based film including polyethylene terephthalate, an acrylic film, a cyclic olefin polymer, a norbornene-based compound, and the like. One or more of the polymer films may be included, but is not limited thereto. The polarizing plate adhesive layer may be formed of the polarizing plate adhesive described above in the first protective layer.

When the second protective layer 400 is a protective coating layer, the second protective layer may be formed directly on the polarizer without the adhesive layer for the polarizing plate.

The protective coating layer can improve good adhesion to the polarizer, transparency, mechanical strength, thermal stability, moisture barrier properties, durability. In one embodiment, the protective coating layer may be formed of an active energy ray curable resin composition comprising an active energy ray curable compound and a polymerization initiator. The active energy ray curable compound may include at least one of a cationically polymerizable curable compound, a radically polymerizable curable compound, a urethane resin, and a silicone resin. The cationically polymerizable curable compound may be an epoxy compound having at least one epoxy group in a molecule, or an oxetane compound having at least one oxetane ring in a molecule. The radically polymerizable curable compound may be a (meth) acrylic compound having at least one (meth) acryloyloxy group in a molecule. The epoxy compound may be at least one of a hydrogenated epoxy compound, a chain aliphatic epoxy compound, a cyclic aliphatic epoxy compound, and an aromatic epoxy compound. The radically polymerizable curable compound may implement a protective coating layer having excellent hardness and mechanical strength and high durability. The radically polymerizable curable compound can be obtained by reacting two or more kinds of (meth) acrylate monomers and functional group-containing compounds having at least one (meth) acryloyloxy group in a molecule, and at least two (meth) acryloyl jade in the molecule. A (meth) acrylate oligomer which has timing is mentioned. As a (meth) acrylate monomer, the monofunctional (meth) acrylate monomer which has one (meth) acryloyloxy group in a molecule | numerator, the bifunctional (meth) acrylate which has two (meth) acryloyloxy groups in a molecule | numerator Monomers, and polyfunctional (meth) acrylate monomers having three or more (meth) acryloyloxy groups in the molecule. The (meth) acrylate oligomer may be a urethane (meth) acrylate oligomer, a polyester (meth) acrylate oligomer, an epoxy (meth) acrylate oligomer, or the like. The polymerization initiator can cure the active energy ray curable compound. The polymerization initiator may comprise one or more of a photocationic initiator, a photosensitizer. Photocationic initiators can be used those commonly known to those skilled in the art. Specifically, the photocationic initiator may use an onium salt containing a cation and an anion. Specifically, cations include diaryl iodonium, triarylsulfonium, bis [4- (diphenylsulfonio) phenyl] sulfide, and the like. Specifically, the anion includes hexafluorophosphate, tetrafluoroborate, hexafluoroantimonate, hexafluoroarsenate, hexachloroantimonate, and the like. A photosensitizer can be used conventionally known to those skilled in the art. Specifically, the photosensitizer may be used at least one of thioxanthone, phosphorus, triazine, acetophenone, benzophenone, benzoin, oxime. The active energy ray curable resin composition may further include conventional additives such as silicone-based leveling agents, ultraviolet absorbers, antistatic agents, and the like.

The second protective layer 400 may have a thickness of 10 μm to 100 μm, specifically 20 μm to 80 μm. In the above range, it can be used for the polarizing plate, it can protect the polarizer.

Although not shown in FIG. 1, an adhesive layer may be further formed on one surface of the second protective layer 400, that is, the surface that does not adhere to the polarizer. The adhesive layer may adhere the polarizing plate to a liquid crystal panel, an OLED panel, or the like. The pressure-sensitive adhesive layer may be formed of a pressure-sensitive adhesive layer such as a (meth) acrylic pressure-sensitive adhesive layer, but is not limited thereto.

Polarizer

The polarizer 100 may emit light incident from the second protective layer 400 to the first protective layer 300.

The polarizer 100 may include a polyvinyl alcohol polarizer manufactured by uniaxially stretching a polyvinyl alcohol film, or a polyene polarizer manufactured by dehydrating a polyvinyl alcohol film. The polarizer may have a thickness of 5 μm to 40 μm. In the above range, it can be used for the polarizing plate.

Hereinafter, the polarizing plate of another embodiment of the present invention will be described.

In the polarizing plate of the present embodiment, except that the adhesive layer for the polarizing plate in the polarizing plate of FIG. 1 is formed of a polarizing plate adhesive including a polyvinyl alcohol-based resin, an imine-type crosslinking agent, an amino formaldehyde-based resin, and an acid of pKa-3 to 5. Is substantially the same as the polarizing plate of one embodiment of the present invention described above.

The polarizing plate of the present invention can be excellent in water resistance even under the evaluation of water resistance by hot water immersion because the adhesive layer for polarizing plate is formed of an adhesive containing polyvinyl alcohol-based resin, imine cross-linking agent, amino formaldehyde-based resin, Gelling time may be delayed, thereby improving processability in manufacturing a polarizing plate. In addition, in the polarizing plate of the present invention, the polarizing plate adhesive layer is formed of an adhesive for a polarizing plate containing an acid of pKa-3 to 5, thereby delaying the reactivity of the amino formaldehyde-based resin to prepare and store the adhesive for the polarizing plate before forming the adhesive layer for the polarizing plate. In this case, the processability can be improved more. The polyvinyl alcohol resin, the imine crosslinking agent, and the amino formaldehyde resin are as described above.

The acid of pKa-3 to 5 delays the reactivity of the amino formaldehyde resin in the mixture of polyvinyl alcohol resin, imine crosslinking agent and amino formaldehyde resin, thereby improving the processability of the adhesive for polarizing plate and affecting the adhesion between the polarizer and the protective film. May not give. Specifically, the acid of pKa -3 to 5, preferably the acid of pKa -1.5 to 5 may include one or more of nitric acid and acetic acid, but is not limited thereto.

The acid of pKa-3 to 5 may be included in an amount of 0.1 to 20 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the polyvinyl alcohol-based resin in the adhesive for polarizing plates. In the above range, the processability of the adhesive for the polarizing plate may be improved, and the adhesion between the polarizer and the protective film may not be affected.

Hereinafter, an optical display device according to an embodiment of the present invention will be described.

The optical display device of the present invention may include the polarizing plate of the present invention. The optical display device may include, but is not limited to, a liquid crystal display device and an organic light emitting display device.

Hereinafter, the configuration and operation of the present invention through the preferred embodiment of the present invention will be described in more detail. However, this is presented as a preferred example of the present invention and in no sense can be construed as limiting the present invention.

Specifications of the components used in the following Examples and Comparative Examples are as follows.

(A) polyvinyl alcohol-based resin: modified polyvinyl alcohol resin (polymerization degree 1200, saponification degree 98.5%, acetoacetylation 5 mol%, solid phase, Z200, Japan Synthetic)

(B) Imine-type crosslinking agent: Polyethylenimine (SP018, Nippon-Catalyst, solid content: 98 weight%)

(C) amino formaldehyde-based resin: methylolmelamine (S-695, DIC, solid content: 60% by weight)

(D) nitric acid: nitric acid (Samjeon Pure Chemical, pKa: -1.4 at 25 ℃, concentration: 60% by weight)

(E) Zirconium compound: Zirconium-ZN (Cheil Hee Won Chemical Co., Ltd.)

(F) Acetic acid: acetic acid (Samjeon Pure Chemical Co., Ltd.)

(G) water: distilled water

(H) Triacetyl cellulose film: moisture permeability 300g / m ² ㆍ day (Fujifilm, thickness: 25㎛, hard coating layer is formed on one surface)

(I) Triacetyl cellulose film: moisture permeability 500g / m ² ㆍ day (Fujifilm, thickness: 20㎛, zero retardation)

(J) Glyoxal

Example  One

To 3200 parts by weight of (G) water, 100 parts by weight of (A) polyvinyl alcohol-based resin was added, dissolved at 95 ° C. for 60 minutes, and cooled to room temperature. On the basis of 100 parts by weight of polyvinyl alcohol-based resin, 1 part by weight of (B) imine-type crosslinking agent and 50 parts by weight of (C) amino formaldehyde-based resin were added to prepare an adhesive for a polarizing plate.

The polyvinyl alcohol film (Japanese synthetic yarn, thickness: 60 micrometers, saponification degree: 99.5%, polymerization degree: 2000) was immersed in 0.3 weight% aqueous solution of iodine, and was dyeed, and it extended | stretched so that draw ratio might be 3.0 times. The stretched polyvinyl alcohol film was immersed in 3 wt% boric acid solution and 2 wt% potassium iodide aqueous solution to correct the color, and dried at 50 ° C. for 4 minutes to prepare a polarizer (thickness: 24 μm).

100 parts by weight of butyl acrylate, 2 parts by weight of acrylic acid, 0.2 parts by weight of 2-hydroxyethyl acrylate and 2,2'-azobisisobutyronitrile in a reaction vessel equipped with a cooling tube, a nitrogen inlet tube, a thermometer and a stirring device. 0.3 parts by weight was added together with ethyl acetate to prepare a solution. It stirred under the nitrogen gas atmosphere in solution, it was made to react at 60 degreeC for 6 hours, and the solution containing the weight average molecular weight 1.7 million acrylic polymer was obtained. Moreover, methyl ethyl ketone was added to the solution containing this acrylic polymer, and the solid polymer concentration obtained the 20-% acrylic polymer solution. 0.3 parts by weight of Soken's L-45 having an isocyanate group was added as a crosslinking agent, and 0.05 parts by weight of Shinetsu's silane coupling agent KMB-403 was added to 100 parts by weight of the acrylic polymer solution to prepare an adhesive solution. . The said adhesive solution was apply | coated so that the thickness after drying might be set to 20 micrometers on the surface of the release sheet which consists of a polyethylene terephthalate film (38 micrometers in thickness) which peeled, and dried, and the adhesive layer was formed.

The prepared polarizing plate adhesive was applied to one surface of the polarizer at a thickness of 100 nm, and the (H) triacetyl cellulose film was laminated. On the other side of the polarizer, the prepared adhesive for polarizing plate was applied to a predetermined thickness, and the (I) triacetyl cellulose film was laminated. Heat treatment was performed for 1 minute in a drying oven at 50 ° C and for 2 minutes in a drying oven at 85 ° C. (I) The above-mentioned pressure-sensitive adhesive layer was bonded to one surface of the triacetyl cellulose film to prepare a polarizing plate.

Example  2 to Example  5 and Comparative example  1 to Comparative example  6

In Example 1, the adhesive composition for polarizing plates was manufactured by the same method except the structure of the adhesive for polarizing plates being changed as Table 1 (unit: weight part) below. Then, a polarizing plate was manufactured in the same manner as in Example 1.

(A) (B) (C) (D) (E) (F) (J) Example 1 100 One 50 0 0 0 0 Example 2 100 One 50 5 0 0 0 Example 3 100 One 50 10 0 0 0 Example 4 100 One 100 10 0 0 0 Example 5 100 5 50 10 0 0 0 Comparative Example 1 100 3 0 5 15 0 0 Comparative Example 2 100 0 35 0 0 10 0 Comparative Example 3 100 0 50 5 0 0 0 Comparative Example 4 100 One 0 0 0 0 0 Comparative Example 5 100 0 50 0 0 0 0 Comparative Example 6 100 0 50 0 0 0 One

* In Table 1, the content of (B), (C), (D), (E), (F), (J) is the content relative to 100 parts by weight of (A), respectively.

The physical properties of the following Table 2 were evaluated for the polarizing plates of Examples and Comparative Examples.

(1) end peeling: The prepared polarizing plate was cut to a length x width 50mm x 50mm square size having the absorption axis direction of the polarizer at an angle of 45 degrees, and the release film of the pressure-sensitive adhesive layer was peeled off and then attached to a glass plate to prepare a sample. . The sample is completely immersed in 44 ° C. water, and after 12 hours, the length separated from the center of the sample end is measured.

◎: separated length between polarizer and first protective layer is 0.1mm or less

○: The separated length between the polarizer and the first protective layer is greater than 0.1 mm and less than 1 mm.

(Triangle | delta): The separated length between a polarizer and a 1st protective layer is more than 1 mm 5 mm or less

X: the separated length between the polarizer and the first protective layer is more than 5 mm

(2) the blister area between the polarizer and the protective layer: The prepared polarizing plate was cut to a length x width of 50 mm x 50 mm square size having the absorption axis direction of the polarizer at a 45 degree angle, and the release film of the pressure-sensitive adhesive layer was peeled off. A sample was prepared by adhesion. Completely immersing the specimen in water 44 ℃ and calculated the area between the blister 12 hours after the unit area is 100 (mm) polarizer and the first protective layer ² per.

(3) Gelation time: 10 ml of the adhesive for polarizing plate is placed in a vial (a round bottom of 490 mm ² and a total volume of 15 ml transparent vials of 6 cm in height), and when the vials are turned over, there is a part where no adhesive flows. It evaluated by the time to make. The longer the gelation time, the better the processability in manufacturing the polarizing plate.

(4) Immersion adhesiveness: In order to confirm the immersion adhesiveness of the polarizing plate, the polarizing plate was immersed in water at room temperature for 1 hour, then taken out, and the water was wiped off, and the cutter tip was inserted between the first protective layer at the end and the polarizer. X that the tip of the knife did not enter between the first protective layer and the polarizer was ◎, the tip of the knife entered a little, the tip of the knife entered a little, but there was a certain strength and the protective film was torn in the middle. .

End
Peeling Blister area between polarizer and first protective layer ((mm) ² ) Gel time Immersion Adhesion Example 1 ○ 2 4 hours ◎ Example 2 ◎ 0.5 48 hours ○ Example 3 ◎ 8 72 hours ○ Example 4 ◎ 4.5 24 hours ○ Example 5 ◎ 9 48 hours ○ Comparative Example 1 ○ 17 * △ Comparative Example 2 △ 8 12 hours ○ Comparative Example 3 △ 2 4 days △ Comparative Example 4 X 36 * ◎ Comparative Example 5 △ 4.5 4 hours ○ Comparative Example 6 △ 5 4 hours ○

* Comparative Example 1 and Comparative Example 4 does not gel even if the time persists.

As shown in Table 2, the polarizing plate of the present invention can suppress blister generation between the polarizer and the protective layer even when hot water is immersed, has a long gelling time, excellent processability, excellent adhesion even when immersed, and hot water immersion End peeling can also be minimized.

Simple modifications and variations of the present invention can be easily made by those skilled in the art, and all such modifications or changes can be seen to be included in the scope of the present invention.

Claims (13)

Polarizer; A first protective layer laminated on one surface of the polarizer by an adhesive layer for polarizing plates; And a second protective layer laminated on the other surface of the polarizer,
The adhesive layer for the polarizing plate is formed of an adhesive for a polarizing plate containing a polyvinyl alcohol-based resin, an imine crosslinking agent and an amino formaldehyde-based resin,
The first protective layer includes a protective film having a moisture permeability of 300 g / m ² · day or more,
The polarizing plate is a polarizing plate of which the total area of the blisters formed between the polarizer and the first protective layer after being left in water at 44 ° C. for 12 hours is 10 (mm) ² or less per 100 (mm) ² of the polarizing plate. .
According to claim 1, wherein the adhesive for polarizing plate
100 parts by weight of the polyvinyl alcohol-based resin,
0.1 parts by weight to 20 parts by weight of the imine crosslinking agent,
10 to 150 parts by weight of the amino formaldehyde-based resin, the polarizing plate.
The method of claim 1, wherein the amino formaldehyde-based resin comprises at least one of a condensate of methylol urea, methylol melamine, alkylated methylol urea, alkylated methylolated melamine, acetoguanamine, benzoguanamine and formaldehyde That is, a polarizing plate.
The polarizing plate of claim 1, wherein the imine crosslinking agent comprises polyethyleneimine.
The polarizing plate according to claim 1, wherein the adhesive for polarizing plate further comprises an acid of pKa -3 to 5 at 25 ° C.
The polarizing plate according to claim 5, wherein the acid of pKa-3 to 5 includes at least one of nitric acid and acetic acid.
The polarizing plate of Claim 1 in which the said adhesive agent for polarizing plates does not contain a zirconium compound.
The polarizing plate of claim 1, wherein the second protective layer comprises a protective film having a moisture permeability of 300 g / m ² · day or more.
The adhesive for polarizing plates containing polyvinyl alcohol-type resin, an imine-type crosslinking agent, and amino formaldehyde type resin, The adhesive for polarizing plates is a gelation time of 4 hours or more, The adhesive for polarizing plates.
10. The method of claim 9, wherein the polarizing plate adhesive
100 parts by weight of the polyvinyl alcohol-based resin,
0.1 parts by weight to 20 parts by weight of the imine crosslinking agent,
Adhesives for polarizing plates comprising 10 parts by weight to 150 parts by weight of the amino formaldehyde-based resin.
The adhesive for polarizing plates according to claim 9, wherein the adhesive for polarizing plates further comprises an acid of pKa -3 to 5 at 25 ° C.
The adhesive for polarizing plates according to claim 11, wherein the acid of pKa-3 to 5 includes at least one of nitric acid and acetic acid.
An optical display device comprising the polarizing plate of any one of claims 1 to 8.

Images