KR20130058351A

KR20130058351A - Adhesive composition and polarizing plate using the same

Info

Publication number: KR20130058351A
Application number: KR1020110124313A
Authority: KR
Inventors: 조천희; 유민근; 최한영
Original assignee: 동우 화인켐 주식회사
Priority date: 2011-11-25
Filing date: 2011-11-25
Publication date: 2013-06-04

Abstract

PURPOSE: An adhesive composition for polarizing plates is provided to facilitate adhesion of a protective film and to have excellent adhesion while maintaining excellent optical performance. CONSTITUTION: An adhesive composition for polarizing plates comprises a polyvinyl alcohol-based resin, a crosslinking agent, and an amine-based resin which has a pH of 7.5-9 and is water-soluble and cationic. The main chain of the amine-based resin is N,N'-bis(2-aminoethyl)-1,2-ethanediamine. The amine-based resin is a copolymer of one or more compounds selected from epoxy-based, amino-based, and isobenzofuranedione-based. A polarizing plate comprises a polarizer; an adhesive layer which is laminated on one side or both sides of the polarizer and contains the adhesive composition; and a polarizer protection film which is laminated on the adhesive layer. [Reference numerals] (AA) Absorption axis(casting direction)

Description

Adhesive composition for polarizing plates and a polarizing plate including the same {ADHESIVE COMPOSITION AND POLARIZING PLATE USING THE SAME}

The present invention relates to a polarizing plate adhesive composition and a polarizing plate comprising the same easy bonding of the polarizer and the hard-adhesive protective film.

The polarizing plate has a structure in which a transparent protective film is laminated on both sides or one side of a polarizer made of a polyvinyl alcohol-based resin in which dichroic dye is adsorbed and oriented.

The polarizer is produced by a method of longitudinally uniaxial stretching and dyeing with a dichroic dye on a polyvinyl alcohol-based resin film, followed by boric acid treatment to perform a crosslinking reaction, and washing with water and drying. As the dichroic dye, iodine or a dichroic organic dye is used. A polarizing plate is manufactured by stacking a protective film on both surfaces or one side of the polarizer thus manufactured, and introduces the manufactured polarizing plate into the liquid crystal display device.

Cellulose-based film is used a lot of protective film, the thickness is usually about 30 to 120㎛. In addition, the protective film often uses an adhesive made of an aqueous solution of polyvinyl alcohol-based resin when laminated.

However, the cellulose-based protective film has a disadvantage in that it can be bonded by an adhesive only after passing through a process of saponifying (alkali treatment) the surface of the protective film when bonding the polarizer. Currently, UV adhesives and the like have been proposed as adhesives capable of bonding cellulose protective films without performing saponification processes. However, the UV adhesive has a lower adhesive strength than the water-based adhesive, which may induce cracking of the polarizer in the thermal shock test, and has a disadvantage in that the price is very high and the economic efficiency is low.

On the other hand, the cellulose-based protective film has a disadvantage in that the polarizing plate performance is lowered or the protective film and the polarizer are peeled off due to low moisture and heat resistance, so that at least one protective film is composed of various resins other than cellulose acetate-based resins (acrylic and propylene-based resins). There is an attempt to do so.

An object of the present invention is to provide an adhesive composition for a polarizing plate that can easily contact a hard-adhesive protective film, such as an unmicronized cellulose film, an acrylic film, a propylene film, and the like, which are difficult to bond with a conventional water-based adhesive for a polarizing plate. .

In order to achieve the above object, the present invention provides an adhesive composition for a polarizing plate comprising a polyvinyl alcohol-based resin, a crosslinking agent and an amine-based resin having a pH of 7.5 to 9 and a water-soluble and cationic.

The main chain of the amine-based resin may be N, N'-bis (2-aminoethyl) -1,2-ethanediamine.

The amine-based resin may be further copolymerized with one or more compounds selected from epoxy, amino and isobenzofurandione.

The adhesive composition may further include an additive selected from the group consisting of a water-soluble aziridine compound, a plasticizer, a silane coupling agent, an antistatic agent, a fine particle, an alcohol, and a leveling agent.

The additive may include 0.01 to 3 parts by weight based on 100 parts by weight of polyvinyl alcohol-based resin (based on solids content).

For 100 parts by weight of the polyvinyl alcohol-based resin (based on the solid content), 3 to 25 parts by weight of a glyoxylate crosslinking agent, and a pH of 7.5 to 9 and a water-soluble and cationic amine resin may include 30 to 70 parts by weight. .

In addition, the present invention is a polarizer; An adhesive layer laminated on one or both surfaces of the polarizer and containing the adhesive composition; And it provides a polarizing plate comprising a polarizer protective film laminated on the adhesive layer.

The polarizer protective film may be a surface treated by a dry treatment method selected from the group consisting of plasma, corona and primer.

The polarizer protective film may be selected from the group consisting of an acrylic-based or propylene-based protective film, and an uncellified cellulose-based protective film whose surface is dried.

The adhesive composition of this invention is easy to adhere | attach the hard-adhesive protective film (non-micronized cellulose film, acrylic film, propylene film etc.) which is difficult to conventionally bond with the water-based adhesive agent for polarizing plates.

In addition, the adhesive composition of the present invention is not only excellent in adhesive strength while maintaining the optical properties equivalent to those of the prior art, but also excellent in polarizer and polarizer protective film and adhesive force and water resistance (color fading phenomenon of the polarizer) under high temperature and humidity conditions. There is an effect to improve.

Figure 1 shows the water resistance test method of the polarizing plate.

Hereinafter, the present invention will be described in detail.

The adhesive composition for polarizing plates of this invention contains a polyvinyl alcohol-type resin, a crosslinking agent, and an amine-type resin which is pH-9-9, water-soluble, and cationic.

As the polyvinyl alcohol-based resin, a modified polyvinyl alcohol resin such as acetoacetyl group modification, carboxy group modification, methylol group modification, amino group modification, epoxy modification, etc. may be used, and acetoacetyl group modified polyvinyl having excellent durability in terms of high reactivity. Alcohol resin is more preferable.

Acetoacetyl group-modified polyvinyl alcohol-based resin can be obtained by reacting polyvinyl alcohol-based resin with diketene by a known method. Specifically, a method of dispersing a polyvinyl alcohol-based resin in a solvent such as acetic acid and then adding diketene thereto, and dissolving the polyvinyl alcohol-based resin in a solvent such as dimethylformamide or dioxane in advance and then diketene It can be obtained by a method of adding or a method in which diketene gas or liquid diketene is directly contacted with polyvinyl alcohol-based resin. The acetoacetyl group-modified polyvinyl alcohol-based resin is not particularly limited as long as the acetoacetyl group modification is 0.1 mol% or more, preferably 0.1 to 40 mol%, more preferably 1 to 20 mol%, most preferably 2 It is good to be 7 mol%. When the degree of modification of the acetoacetyl group is less than 0.1 mol%, the water resistance of the adhesive layer is insufficient, which is unsuitable. When the degree of modification of the acetoacetyl group exceeds 40 mol%, the effect of improving the water resistance may be insignificant.

The saponification degree of the acetoacetyl group-modified polyvinyl alcohol-based resin is also not particularly limited, but is preferably 80 mol% or more, and more preferably 85 mol% or more. When the saponification degree of polyvinyl alcohol-type resin contained in an adhesive composition is low, since sufficient water solubility becomes difficult to express, adhesiveness tends to be inadequate.

Although the polyvinyl alcohol used when manufacturing an acetoacetyl-group modified polyvinyl alcohol-type resin is not specifically limited, In order to express high adhesiveness between the polarizing film and a protective film in a polarizing plate, average polymerization degree exists in the range of 100-3,000. It is preferable to exist, and it is preferable that average saponification degree exists in the range of 80-100 mol%.

Examples of the products include Z-100, Z-200, Z-200H, Z-210, Z-220 and Z-320 (manufactured by Gohsefymer Japan Synthetic Chemicals).

The crosslinking agent serves to improve adhesion and durability between the polyvinyl alcohol-based resin and the polarizer and the polarizer protective film, and to maintain the shape of the adhesive and the reliability at high temperatures.

Isocyanate-based, epoxy-based, peroxide-based, metal chelate-based, oxazoline-based, melamine-based, glyoxylate-based, and the like may be used, and one or two or more thereof may be mixed. Glyoxylates which are advantageous in terms of double adhesion and durability improvement are preferred.

The present invention is specifically described below with respect to glyoxylate crosslinking agent which is a preferred crosslinking agent component, but is not limited thereto.

As the glyoxylate, an alkali metal salt or alkaline earth metal salt of glyoxylic acid may be used. Alkali metal salts and alkaline earth metal salts of glyoxylic acid can obtain almost the same effects, and there is no restriction in particular in their use. This is because both alkali and alkaline earth metals have low electronegativity, and the carboxylate salts of the metal or earth metal have similar chemical properties. In addition, since the portion serving as a crosslinking agent of acetoacetyl group-modified polyvinyl alcohol is an aldehyde group of glyoxylate, it is expected that the metal or the earth metal will have the same effect.

The glyoxylates include alkali metal salts such as lithium glyoxylate, sodium glyoxylate, potassium glyoxylate, alkali earth metal salts such as magnesium glyoxylate, calcium glyoxylate, strontium glyoxylate, and barium glyoxylate. Can be used. Among them, in consideration of solubility in water, an alkali metal salt is preferable, and sodium glyoxylate is more preferable.

Such a crosslinking agent contains 3 to 25 parts by weight, preferably 5 to 20 parts by weight, based on 100 parts by weight of the polyvinyl alcohol-based resin (based on the solid content). When the said content is less than 3 weight part, the water resistance of a polarizing plate does not fully express. Moreover, when content exceeds 25 weight part, there exists a problem that the optical characteristic (transmittance degree, polarization degree) of a polarizing plate falls.

The amine resin serves to improve the adhesion (adhesive force) between the polyvinyl alcohol resin and the polarizer and the polarizer protective film. The amine resin is cationic and has a pH of 7.5 to 9. Further, it is water-soluble in consideration of miscibility with the polyvinyl alcohol-based resin.

When an anionic resin is used, the adhesion (adhesion) between the polarizer and the polarizer protective film may be lowered. In addition, when the pH is less than 7.5, the water resistance may be lowered, and when the pH is greater than 9, the adhesiveness (adhesive force) may be lowered.

The amine-based resin may be a resin containing N, N'-bis (2-aminoethyl) -1,2-ethanediamine as a main chain, and may be selected from epoxy resins, amino resins, and isobenzofuran dione resins. It is possible to more advantageously use the above-mentioned copolymer in which more than one kind of compound is copolymerized to achieve the effect of the present invention.

Commercially available products may be Sumirez Resin SPI-203 (50) H manufactured by Taoka Chemical Co., and Sumirez Resin SPI-106N manufactured by Taoka Chemical.

Such amine resin contains 30 to 70 parts by weight, preferably 25 to 65 parts by weight, based on 100 parts by weight of the polyvinyl alcohol resin (based on the solid content). When content is less than 30 weight part, there exists a problem that adhesiveness (adhesive force) falls, and when it exceeds 70 weight part, there exists a problem of compatibility with polyvinyl alcohol-type resin.

In addition, the adhesive composition may use additives such as aziridine-based compounds, plasticizers, silane coupling agents, antistatic agents, fine particles, alcohols and leveling agents generally used in the art within a range that does not impair the desired effect. . It is preferable to use an alcohol, a leveling agent, etc. especially in order to improve the spreadability of an adhesive bond layer forming composition. In addition, in consideration of water resistance, it is preferable to use an aziridine compound.

It is preferable that the adhesive composition is liquid in order to form a uniform adhesive layer on the surface of the polarizer or the protective film as the adherend. Such liquid adhesives may be used in the form of a solution or dispersion of various solvents. In consideration of the coating properties of the substrate, a solution type is preferable, and in consideration of stability, a solution or dispersion with water as a solvent is preferable.

In addition, for the purpose of shortening the drying step, a water / alcohol mixed solvent may be used which is easily mixed with water in the adhesive solution and which contains an alcohol solvent having a lower boiling point than water. It is preferable that boiling point of an alcoholic solvent is 100 degrees C or less, especially 80 degrees C or less, or 70 degrees C or less.

The present invention is a polarizer; An adhesive layer laminated on one or both surfaces of the polarizer and containing the adhesive composition; And it provides a polarizing plate comprising a polarizer protective film laminated on the adhesive layer.

The polarizer is a dichroic dye adsorbed on the stretched polyvinyl alcohol-based film.

The polyvinyl alcohol-based resin constituting the polarizer can be obtained by saponifying a polyvinyl acetate-based resin. Examples of the polyvinyl acetate resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Other monomers copolymerizable with vinyl acetate include acrylamide monomers having an unsaturated carboxylic acid type, an unsaturated sulfonic acid type, an olefin type, a vinyl ether type, and an ammonium group. The polyvinyl alcohol resin may also be modified. For example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The saponification degree of the polyvinyl alcohol-based resin is usually 85 to 100 mol%, preferably 98 mol% or more. The polymerization degree of the polyvinyl alcohol-based resin is usually 1,000 to 10,000, preferably 1,500 to 5,000.

What formed such a polyvinyl alcohol-type resin into a film is used as a raw film of a polarizer. The method of forming the film of the polyvinyl alcohol-based resin is not particularly limited, and a known method can be used. The thickness of the original film is not particularly limited, and may be, for example, 10 to 150 mu m.

The polarizer of the present invention is produced by continuously uniaxially stretching a polyvinyl alcohol-based film in an aqueous solution, staining with a dichroic dye and adsorbing, treating with an aqueous solution of boric acid, and washing and drying.

The process of uniaxially stretching the polyvinyl alcohol-based film may be performed before dyeing, may be simultaneously performed with dyeing, or may be performed after dyeing. When the uniaxial stretching is performed after dyeing, it may be performed before boric acid treatment, or may be performed during boric acid treatment. Of course, it is also possible to perform uniaxial stretching in these multiple steps. For uniaxial stretching, rolls or heat rolls with different circumferential speeds can be used. In addition, uniaxial stretching may be dry stretching extending | stretching in air | atmosphere, and wet extending | stretching extending | stretching in the state swollen with a solvent may be sufficient as it. The stretching ratio is usually 4 to 8 times.

As a process of dyeing a stretched polyvinyl alcohol-type film with a dichroic dye, the method of immersing a polyvinyl alcohol-type film in the aqueous solution containing a dichroic dye can be used, for example. As a dichroic dye, iodine or a dichroic dye is used. It is preferable that the polyvinyl alcohol film is pre-immersed in water before dyeing to swell.

When using iodine as a dichroic dye, the method of immersing and dyeing a polyvinyl alcohol-type film in the dyeing aqueous solution containing iodine and potassium iodide can be used normally. Usually, the content of iodine in an aqueous solution for dyeing is 0.01 to 1 part by weight with respect to 100 parts by weight of water (distilled water), and the content of potassium iodide is 0.5 to 20 parts by weight with respect to 100 parts by weight of water. The temperature of the aqueous solution for dyeing is usually 20 to 40 ° C., and the immersion time (dyeing time) is usually 20 to 1,800 seconds.

When using a dichroic dye as a dichroic dye, the method of immersing and dyeing a polyvinyl alcohol-type resin film in the aqueous solution containing water-soluble dichroic dye is employ | adopted normally. The content of the dichroic dye in this aqueous solution is usually 1 × 10 ^-4 to 10 parts by weight, preferably 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 20-80 degreeC normally, and the immersion time in this aqueous solution is 10-1,800 second normally.

The step of treating the dyed polyvinyl alcohol film with boric acid can be carried out by immersing it in an aqueous solution containing boric acid. The content of boric acid in an aqueous solution containing boric acid is usually 2 to 15 parts by weight, preferably 5 to 12 parts by weight based on 100 parts by weight of water. When iodine is used as the dichroic dye, the boric acid-containing aqueous solution preferably contains potassium iodide, and the content thereof is usually 0.1 to 15 parts by weight, preferably 5 to 12 parts by weight with respect to 100 parts by weight of water. The temperature of the boric acid-containing aqueous solution is usually 50 ° C or higher, preferably 50 to 85 ° C, more preferably 60 to 80 ° C, and the immersion time is usually 60 to 1,200 seconds, preferably 150 to 600 seconds, more preferably. Preferably it is 200 to 400 seconds.

After the boric acid treatment, the polyvinyl alcohol-based film is usually washed with water and dried. Washing treatment can be performed by immersing the boric acid-treated polyvinyl alcohol-based film in water. The temperature of the water of a washing | cleaning process is 5-40 degreeC normally, and immersion time is 1-120 second normally. A polarizer can be obtained by drying after washing with water. The drying treatment can usually be carried out using a hot air dryer or a far infrared heater. The drying treatment temperature is usually 30 to 100 ° C, preferably 50 to 80 ° C, and the drying time is usually 60 to 600 seconds, preferably 120 to 600 seconds.

The thickness of the polarizer produced as described above is 5 to 40㎛.

The polarizer protective film is not particularly proposed to be excellent in transparency, mechanical strength, thermal stability, moisture shielding, isotropy, and the like, and specifically, acrylic, cellulose, polyolefin, or polyester may be used.

For example, Acrylic resin, such as polymethyl (meth) acrylate and polyethyl (meth) acrylate; Polyester resins such as polyethylene terephthalate, polyethylene isophthalate, polyethylene naphthalate, and polybutylene terephthalate; Cellulose resins such as diacetyl cellulose and triacetyl cellulose; Polyolefin resins such as polyethylene, polypropylene, cyclo-based or norbornene-structured polyolefin-based and ethylene-propylene copolymers; A protective film containing these etc. can be mentioned.

The thickness of the polarizer protective film is 10 to 200㎛, preferably 10 to 150㎛. In addition, when the polarizer protective film is laminated on both sides of the polarizer may maintain the same or different thickness.

The bonding easy process can be performed to the surface joined with the polarizer of a protective film. Examples of the easy-to-bond treatment include dry treatment such as primer treatment, plasma treatment, corona treatment, chemical treatment such as alkali treatment (soap treatment), and coating treatment to form an easy adhesive layer.

In particular, in the present invention, since a protective film (for example, an ungelatinized cellulose-based protective film) which is not subjected to a chemical treatment such as an alkali treatment (saponification treatment) is also easily bonded to the polarizer, its process is not particularly required.

In addition, the acrylic or propylene protective film whose surface is represented by the hard adhesive protective film and the dry-treated protective film together with the uncellified cellulose protective film is also easy to bond.

The thickness of the adhesive layer is usually about 0.01 to 10 µm, preferably 0.05 to 5 µm, and most preferably 0.1 to 1 µm. The surface which is not bonded to the polarizer of the protective film may be subjected to a treatment for the purpose of hard coat treatment, antireflection treatment, sticking prevention, diffusion or antiglare.

The bonding method may be a conventional method in the art, for example, using a casting method, a meyer bar coating method, a gravure coating method, a die coating method, a dip coating method, a spray coating method, or the like on the bonding surface of the polarizer or the protective film. After apply | coating an adhesive composition, the method of joining these is mentioned. The flexographic method is a method in which the polarizer or the protective film is moved in the vertical direction, the horizontal direction, or the inclined direction between the two, while applying the adhesive composition to the joint surface. After applying the adhesive composition, a polarizer or a protective film is put on a nip roll or the like and bonded.

After bonding the polarizer and the protective film may be a drying treatment. The drying treatment is carried out, for example, by spraying hot air, and the drying temperature is appropriately selected in the range of 40 to 100 ° C, preferably 60 to 100 ° C. Drying time may be about 20 to 1,200 seconds. After drying, curing is preferably performed at room temperature or slightly higher, for example, at a temperature of 20 to 50 ° C. for about 12 to 600 hours. The thickness of an adhesive bond layer after drying is 0.001-5 micrometers normally, Preferably it is 0.01 micrometer-2 micrometers, More preferably, it is 0.01-1 micrometer or less. When the thickness of an adhesive bond layer exceeds 5 micrometers, it will be easy to produce the external appearance problem of a polarizing plate.

Surface treatment layers such as a hard coating layer, an antireflection layer, an antiglare layer, an antistatic layer and the like may be further laminated on the other side of the polarizer having the polarizer protective film bonded to one surface thereof. In addition, the optical functional film may be further laminated by the pressure-sensitive adhesive layer. As the optical functional film, for example, an optical compensation film in which a liquid crystalline compound or a polymer compound thereof is oriented on the surface of a substrate, reflective polarization that transmits polarized light of any kind and reflects polarized light having a property opposite thereto. Separation film, retardation film containing polycarbonate resin, retardation film containing cyclic polyolefin-based resin, anti-glare function film having an uneven shape on the surface, an additional film subjected to the surface anti-reflection treatment, a reflection film having a reflection function on the surface, The semi-transmissive reflective film etc. which have a reflection function and a transmission function together are mentioned.

In addition, the present invention may include a polarizing plate to form a liquid crystal display device.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention. Such variations and modifications are intended to be within the scope of the appended claims.

Preparation Example: Polarizer Manufacturing

A 75 µm thick polyvinyl alcohol film having an average degree of polymerization of 2,400 and a saponification degree of 99.9 mol% or more was uniaxially stretched by about 5 times dry, and immersed in water (distilled water) at 60 ° C. for 1 minute while being stretched. After immersion for 60 seconds in an aqueous solution of 28 ℃ having a weight ratio of iodine / potassium iodide / distilled water of 0.05 / 5/100. Thereafter, the weight ratio of potassium iodide / boric acid / distilled water was immersed in an aqueous solution of 72 ° C. having 8.5 / 8.5 / 100 for 300 seconds, washed with distilled water at 26 ° C. for 20 seconds, and dried at 65 ° C. to give iodine a PVA film. Adsorbed oriented polarizers were prepared.

Example 1

(1) adhesive composition

An aqueous solution having a solid content of 5% by weight was prepared by dissolving acetoacetyl group-modified polyvinyl alcohol-based resin (Cosenol Z200, Nippon Synthetic Chemical Co., Ltd.) having a degree of saponification of 99.2 mol% in water (distilled water).

5 parts by weight of sodium glyoxalate (10% by weight aqueous solution) crosslinking agent to 100 parts by weight (solid content) of the acetoacetyl group-modified polyvinyl alcohol-based resin aqueous solution, an amine-based resin having a pH of 8, water-soluble and cationic (Sumirez Resin SPI-203) (50) H product, Taoka Chemical Co., Ltd.) 30 parts by weight were mixed to prepare an adhesive composition. At this time, each of the components were mixed based on the solid content.

(2) Polarizer

After applying the adhesive composition of said (1) so that a dry film thickness might be 0.1 micrometer on both surfaces of the polarizer by which the iodine of the manufacture example was adsorption-oriented, the protective film was bonded using the niprole. After drying for 5 minutes in a hot air dryer of 80 ℃ to prepare a polarizing plate.

The protective film was prepared using a triacetyl cellulose protective film, an untrimmed triacetyl cellulose protective film, a corona-treated acrylic protective film and a corona-treated propylene protective film, respectively, to prepare four polarizing plates.

Examples 2-8 and Comparative Examples 1-5

A polarizing plate was prepared in the same manner as in Example 1, using the composition of the components as shown in Table 1 below.

division
(Parts by weight) Polyvinyl
Alcohol
Suzy Cross-linking agent Amine-based resin additive Kinds pH Properties Example 1 100 Glyoxylic acid
Sodium (5) Sumirez Resin SPI-203 (50) H (30) 8 Cationic - Example 2 100 Glyoxylic acid
Sodium (5) Sumirez Resin SPI-203 (50) H (40) 8 Cationic - Example 3 100 Glyoxylic acid
Sodium (5) Sumirez Resin SPI-203 (50) H (50) 8 Cationic - Example 4 100 Glyoxylic acid
Sodium (5) Sumirez Resin SPI-203 (50) H (70) 8 Cationic - Example 5 100 Glyoxylic acid
Sodium (5) Sumirez Resin SPI-106N (50) 9 Cationic - Example 6 100 Glyoxylic acid
Sodium (5) Sumirez Resin SPI-203 (50) H (50) 8 Cationic Leveling agent
(3) Example 7 100 Glyoxylic acid
Sodium (5) Sumirez Resin SPI-203 (50) H (50) 9 Cationic Aziridine
(5) Conduct 8 100 Melamine (5) Sumirez Resin SPI-203 (50) H (50) 8 Cationic - Comparative Example 1 100 Glyoxylic acid
Sodium (5) - - - - Comparative Example 2 100 Glyoxylic acid
Sodium (5) Sumirez Resin 7200A 6.5 Anionic - Comparative Example 3 100 Glyoxylic acid
Sodium (5) Sumirez Resin 1001 6.0 Cationic - Comparative Example 4 100 Glyoxylic acid
Sodium (5) PAS-J-81 7 Cationic - Comparative Example 5 100 Glyoxylic acid
Sodium (5) Sumirez Resin SPI-102A 10.5 Cationic - Polyvinyl alcohol-based resin: Acetoacetyl group-modified polyvinyl alcohol-based resin (Cosenol Z200, Japan Synthetic Chemical Co., Ltd.)
Sumirez Resin SPI-203 (50) H: Taoka Chemical Co., Ltd.
Sumirez Resin SPI-106N (50): Taoka Chemical Co., Ltd.
Sumirez Resin 7200A: Taoka Chemical Company
Sumirez Resin 1001: Taoka Chemical Company
PAS-J-81: Nittobo
Sumirez Resin SPI-102A: Taoka Chemical Company
Leveling Agent: Surfynol 465, ISA
Aziridine: CX-100, DSM

Experimental Example

The physical properties of the polarizing plates prepared in Examples and Comparative Examples were measured by the following method, and the results are shown in Table 2 below.

1. Adhesion (Cutter Evaluation)

The prepared polarizing plate was allowed to stand at room temperature for 1 hour, and then a cutter blade was inserted between each polarizing plate (between the polarizing plate and the polarizing plate protective film), and the way in which the blade was pushed was evaluated according to the following criteria .

[Assessment Methods]

A: The cutter blade does not enter any film.

○: When pushing the blade, it stops when the blade reaches 1 to 2 mm between at least one of the films.

?: When the blade is pushed, it stops when the blade enters 3 to 5 mm between at least one of the films.

X: When pushing the blade, the blade is easily inserted between at least one of the films.

2. Water resistance

The prepared polarizing plate was allowed to stand for 24 hours under an environment of 23 ° C and a relative humidity of 55%, and tested for water resistance at room temperature. First, the polarizing plate was cut into a rectangular shape of 5 cm x 2 cm with the absorption axis (stretching direction) of the polarizing plate as the long side to prepare a sample, and the dimension in the long side direction was measured accurately. Here, the sample exhibits uniform color uniformly over the entire surface due to iodine adsorbed on the polarizer. As shown in FIG. 1, (A) shows that the short side of the sample 1 is gripped by the gripper 5 before being immersed in warm water, and (B) shows that the gripped sample 1 It is a figure of the shrinked sample 4 after immersing about 80% of the longitudinal direction in the 60 degreeC hot water bath, and holding it for 4 hours. After the immersion is completed, the sample 4 is taken out of the water bath to wipe off moisture, and the shrinkage of the polarizer is measured. Specifically, the distance from the end 1a of the protective film in the center of the short side of the sample 1 to the end of the contracted polarizer 4 was measured, which was defined as the shrinkage length. In addition, in FIG. 1B, the polarizer 4 positioned in the middle of the polarizing plate contracts by hot water immersion, and a region 2 in which the polarizer 4 does not exist is formed between two protective films. Further, by immersion of hot water, iodine elutes from the periphery of the polarizer 4 in contact with the warm water, whereby a portion 3 in which the color is missing is formed in the periphery of the sample 1. This discoloration degree was measured from the end of the contracted polarizer 4 at the center of the short side of the sample 1 to the region in which the color peculiar to the polarizing plate remained, which was defined as the iodine missing length. The total length of the contraction length and the iodine omission length was defined as the total erosion length X. That is, the total erosion length X is unique to the polarizing plate from the end 1a of the sample 1 at the center of the short side of the sample 1. The distance to the area where the color remains. It can be judged that the smaller the shrinkage length, iodine elimination length, and total erosion length X, the higher the adhesion (hot water resistance) in the presence of water.

[Assessment Methods]

◎: total erosion length (X) <2 mm

○: 2 mm ≤ total erosion length (X) <3 mm

△: 3 mm ≤ total erosion length (X) <5 mm

× 5 mm ≤ total erosion length (X)

3. Optical properties (transmittance, polarization degree) (%)

The prepared polarizing plate was cut to a size of 4 cm × 4 cm to prepare a specimen, and the specimen was attached to a measurement holder, and then the transmittance was measured using an ultraviolet visible spectrometer (V-7100, manufactured by JASCO). At this time, the polarization degree is defined by the following equation (1).

(Wherein T ₁ is the parallel transmittance obtained when the pair of polarizers are arranged in parallel with the absorption axis, and T ₂ is the orthogonal transmittance obtained when the pair of polarizers are arranged in the state where the absorption axes are orthogonal) .

division Protective film Adhesion durability Optical characteristic Transmittance (%) Polarization degree (%) Example 1 Unchecked Triacetylcellulose ○ ◎ 43.1 99.99 Example 2 Unchecked Triacetylcellulose ◎ ◎ 43.2 99.99 Example 3 Unchecked Triacetylcellulose ◎ ◎ 43.3 99.99 Example 4 Unchecked Triacetylcellulose ◎ ◎ 43.2 99.99 Example 5 Unchecked Triacetylcellulose ◎ ◎ 43.1 99.99 Example 6 Unchecked Triacetylcellulose ◎ ◎ 43.1 99.99 Example 7 Saponified triacetylcellulose ◎ ◎ 43.4 99.99 Unchecked Triacetylcellulose ◎ ◎ 43.1 99.99 Corona treated acrylic ◎ ◎ 43.3 99.99 Corona treated propylene ○ ◎ 42.8 99.99 Example 8 Unchecked Triacetylcellulose ○ ◎ 43.2 99.99 Comparative Example 1 Unchecked Triacetylcellulose × × 43.2 99.99 Saponified triacetylcellulose ○ ○ 43.1 99.99 Comparative Example 2 Unchecked Triacetylcellulose × × 43.3 99.99 Comparative Example 3 Unchecked Triacetylcellulose × △ 43.2 99.99 Comparative Example 4 Unchecked Triacetylcellulose × △ 43.1 99.99 Comparative Example 5 Unchecked Triacetylcellulose △ × 43.3 99.99

As shown in Table 2, the adhesive composition of Examples 1 to 8 comprising a polyvinyl alcohol-based resin, a crosslinking agent and a pH of 7.5 to 9 and an aqueous and cationic amine resin according to the present invention is more adhesive than Comparative Examples 1 to 5 It was confirmed that (adhesive force) and water resistance were excellent and optical characteristics were equivalent.

1: sample
1a: end of protective film
2: region in which the polarizer does not exist
3: part where color was missing at the periphery of the sample
4: polarizer
5: holding part

Claims

Adhesive composition for polarizing plates containing polyvinyl alcohol-type resin, a crosslinking agent, and an amine-type resin which is pH-9-9, water-soluble, and cationic.

The adhesive composition for polarizing plates of Claim 1 whose main chain of the amine resin is N, N'-bis (2-aminoethyl) -1,2-ethanediamine.

The adhesive composition of claim 2, wherein the amine resin is further copolymerized with at least one compound selected from epoxy, amino, and isobenzofurandione.

The adhesive composition of claim 1, wherein the adhesive composition further comprises an additive selected from the group consisting of a water-soluble aziridine compound, a plasticizer, a silane coupling agent, an antistatic agent, a fine particle, an alcohol, and a leveling agent.

The adhesive composition of claim 4, wherein the additive comprises 0.01 to 3 parts by weight based on 100 parts by weight of the polyvinyl alcohol-based resin (based on the solid content).

According to claim 1, 3 to 25 parts by weight of glyoxylate crosslinking agent, and 30 to 70 parts by weight of water-soluble and cationic amine resin based on 100 parts by weight of the polyvinyl alcohol-based resin (based on solids content) Adhesive composition for polarizing plates containing a part.

A polarizer;
An adhesive layer laminated on one or both surfaces of the polarizer and containing the adhesive composition of any one of claims 1 to 6; And
And a polarizer protective film laminated on the adhesive layer.

The polarizing plate of claim 7, wherein the polarizer protective film is surface-treated by a dry treatment method selected from the group consisting of plasma, corona and primer.

The polarizing plate of claim 8, wherein the polarizer protective film is selected from the group consisting of an acrylic or propylene protective film having a dry surface, and an uncellified cellulose protective film.