KR102378765B1 - Adhesive composition, polarizing plate and image display device using the same - Google Patents

Abstract

The present invention includes an acetoacetyl group-modified polyvinyl alcohol-based resin, a glyoxal-based crosslinking agent, a water-soluble salt of two or more polyvalent metal ions, and an alcohol, so that the spreadability of the adhesive composition is improved and may occur during the process of applying the adhesive composition It relates to an adhesive composition capable of reducing the visibility of foreign substances when mixed with foreign substances, a polarizing plate including the same, and an image display device.

Description

Adhesive composition, polarizing plate and image display device including same {ADHESIVE COMPOSITION, POLARIZING PLATE AND IMAGE DISPLAY DEVICE USING THE SAME}

The present invention relates to an adhesive composition, a polarizing plate comprising the same, and an image display device.

A polarizing plate is usefully used as one of the optical components constituting a liquid crystal display device. A polarizing plate usually has a structure in which protective films are laminated on both sides of a polarizer, and is inserted into a liquid crystal display device. It is also known to provide a protective film on only one side of the polarizer, but in most cases, a layer having an optical function as a separate function, not a simple protective film, is bonded to the other side as a protective film as well.

In general, an iodine-based film in which iodine is adsorbed to polyvinyl alcohol or a dye-based film in which dichroic dye is adsorbed and oriented to polyvinyl alcohol is used as a polarizer, and an aqueous solution of polyvinyl alcohol-based resin ( Although a polarizing plate having a structure in which a protective film such as triacetyl cellulose (TAC) is bonded through an adhesive layer formed using a polyvinyl alcohol-based adhesive) is used, when an aqueous solution of a polyvinyl alcohol-based resin is used, the spreadability of the aqueous solution is poor. , there is a problem in that defective bubbles or foreign substances are easily visually recognized.

In this regard, Japanese Patent Laid-Open No. 6-34816 tried to suppress the bubble defect by adding sodium or potassium salt to the polyvinyl alcohol-based resin aqueous solution to express antifoaming properties, but this may cause foreign substances due to salt precipitation during drying. There is a problem in that the foreign matter generated or mixed during the process appears to be larger than the size, so that the visibility of the foreign material is improved.

Japanese Patent Application Laid-Open No. 6-34816 (Mitsui Toatsu Chemical Co., Ltd.)

In order to solve the above problem, the present invention provides an adhesive composition with improved visibility for foreign substances that may be mixed during the manufacturing process by improving not only water resistance, but also spreadability to the substrate, a polarizing plate and an image display device including the same but it has a purpose.

The adhesive composition according to the present invention for achieving the above object is characterized in that it comprises an acetoacetyl group-modified polyvinyl alcohol-based resin, a glyoxal-based crosslinking agent, a water-soluble salt of two or more polyvalent metal ions, and an alcohol.

In addition, the polarizing plate and image display device according to the present invention for achieving the above object is characterized in that it comprises an adhesive layer made of the adhesive composition.

The adhesive composition according to the present invention contains water-soluble salts of two or more polyvalent metal ions, and water resistance is improved without a decrease in polarization degree, and spreadability is improved by including alcohol to reduce bubble defect rate and to occur when foreign substances are mixed There is an advantage in that the visibility of foreign objects is reduced.

1A) and B) are diagrams of the effect of improving the spreadability of the adhesive composition of the present invention and thus improving the visibility of the foreign material when foreign substances are mixed.
2C) and D) are diagrams schematically illustrating a test method for evaluating water resistance according to an experimental example.

In the present invention, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated.

Hereinafter, preferred embodiments of the present invention will be described in detail.

<Adhesive composition>

The adhesive composition according to one embodiment of the present invention includes an acetoacetyl group-modified polyvinyl alcohol-based resin (A), a glyoxal-based crosslinking agent (B), a water-soluble salt of two or more polyvalent metal ions (C) and an alcohol (D) By doing so, it improves water resistance that prevents the short side of the protective film and the polarizer from separating even under wet heat conditions, suppresses the generation of bubbles, and reduces the visibility of foreign substances that may be mixed during application of the adhesive composition. there is.

Specifically, according to an embodiment of the present invention, the adhesive composition comprises a solution A comprising an acetoacetyl group-modified polyvinyl alcohol-based resin (A), a glyoxal-based crosslinking agent (B) and an alcohol (D); and solution B containing an acetoacetyl group-modified polyvinyl alcohol-based resin (A), a water-soluble salt (C) of two or more polyvalent metal ions, and an alcohol (D); and, by mixing the solution A and the solution B can be manufactured. In this way, when the adhesive composition is prepared as a two-component type, the pot life of the prepared adhesive composition is improved to prevent the adhesive composition from becoming a gel, and by including alcohol, the generation of air bubbles is reduced. suppression, and there is an advantage that can reduce the visibility of foreign substances that may be incorporated during application of the adhesive composition.

When the visibility effect on the foreign material is described with reference to FIGS. 1 (A) and (B), for example, when the adhesive composition 20 of the present invention is applied on one surface of the polarizer 10 ( FIG. 1 ) of A) the foreign material 30 may be mixed, at this time, in the case of the adhesive composition 20 of the present invention, since the spreadability of the composition is improved by including alcohol together, the visibility (X) of the foreign material by the light (00) is When the adhesive composition 21 that does not contain alcohol is applied (FIG. 1B), there is an advantage in that the visibility (X') of the foreign material is reduced.

In addition, according to one embodiment of the present invention, the mixing ratio of the solution A to the solution B is 1:0.5 to 1:1.5, preferably based on the weight of the solid content of the acetoacetyl group-modified polyvinyl alcohol-based resin included in each It can be mixed at a mixing ratio of 1:0.8 to 1:1.3, and when the mixing ratio is satisfied, the adhesive composition and water resistance are further improved, and when the mixing ratio is out of the above range, it is included in solution A or solution B There is a fear that the content ratio between each component to be used is not properly controlled, so that the water resistance or adhesion for the purpose of the present invention is somewhat lowered. Specifically, when the mixing ratio is less than the lower limit of the range, there is a risk that the water resistance is slightly lowered or the visibility of foreign substances is slightly increased, and when it exceeds the upper limit of the range, there is a risk that the adhesion, adhesiveness, etc. are slightly lowered, so it is less preferable Do.

acetoacetyl group denaturalization Polyvinyl alcohol-based resin (A)

By including the acetoacetyl group-modified polyvinyl alcohol-based resin (A), the adhesive composition of the present invention has an effect of improving the adhesion between the protective film and the polarizer.

According to one embodiment of the present invention, the acetoacetyl group-modified polyvinyl alcohol-based resin (A) contained in the solution A may be included in an amount of 20 to 80 parts by weight based on 100 parts by weight of the total solution A, preferably 25 to 70 parts by weight. In addition, the acetoacetyl group-modified polyvinyl alcohol-based resin (A) contained in the B solution may be included in an amount of 15 to 70 parts by weight, preferably 20 to 65 parts by weight, based on 100 parts by weight of the total B solution.

When the content of the acetoacetyl group-modified polyvinyl alcohol-based resin (A) contained in each of the liquid A and the liquid B satisfies the above-mentioned bar, there is an advantage that the adhesive strength can be further improved, and it is included in less than each content range There is a fear that the adhesive strength may be slightly lowered when the content is used, and when included in excess of each content range, the effect of improving the adhesion strength compared to the increased content is insignificant, which may be undesirable from an economic point of view.

The acetoacetyl group-modified polyvinyl alcohol-based resin (A) contains a functional group with high reactivity compared to a polyvinyl alcohol resin modified such as carboxy group-modified, methylol group-modified, and amino group-modified, so it is excellent in durability improvement.

The acetoacetyl group-modified polyvinyl alcohol-based resin (A) may be obtained by reacting the polyvinyl alcohol-based resin with diketene by a known method. Specifically, a method in which a polyvinyl alcohol-based resin is dispersed in a solvent such as acetic acid and then diketene is added thereto. After dissolving the polyvinyl alcohol-based resin in a solvent such as dimethylformamide or dioxane in advance, diketene is added thereto. It can be obtained by a method of adding a polyvinyl alcohol-based resin or a method of directly contacting diketene gas or liquid diketene with a polyvinyl alcohol-based resin. The acetoacetyl group-modified polyvinyl alcohol-based resin (A) is not particularly limited as long as the degree of acetoacetyl group modification is 0.1 mol% or more, preferably 0.1 to 40 mol%, more preferably 1 to 20 mol%, most Preferably, it is good that it is 2-7 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 and thus unsuitable. When the degree of modification of the acetoacetyl group exceeds 40 mol%, the effect of improving water resistance may be insignificant.

Although the degree of saponification of the acetoacetyl group-modified polyvinyl alcohol-based resin (A) is not particularly limited, it is preferably 80 mol% or more, and more preferably 85 mol% or more. When the degree of saponification of the modified polyvinyl alcohol-based resin (A) is less than the above range, sufficient water solubility becomes difficult to be expressed, and thus a problem of lowering adhesion may occur.

The degree of polymerization of the acetoacetyl group-modified polyvinyl alcohol-based resin (A) is preferably within 100 to 1,500. When the polymerization degree of the acetoacetyl group-modified polyvinyl alcohol-based resin (A) is within the above range, there is an effect of improving the adhesion between the polarizer and the protective film in the polarizing plate.

Specifically, the acetoacetyl group-modified polyvinyl alcohol-based resin (A) includes Z-100, Z-200, Z-200H, Z-210, Z-220 and Z-320 (Nippon Synthetic Chemical Gohsefimer). However, the present invention is not limited thereto.

glyoxal crosslinking agent (B)

The adhesive composition of the present invention includes a glyoxal-based crosslinking agent (B).

When the glyoxal-based cross-linking agent (B) is included, the aldehyde group in the glyoxal-based cross-linking agent (B) undergoes a condensation reaction with the hydroxyl group included in the acetoacetyl group-modified polyvinyl alcohol-based resin (A) as well as the polarizer and the protective film. By doing so, there is an effect of improving the degree of crosslinking of the adhesive composition and improving the adhesion and water resistance between the polarizer and the protective film to be bonded using the same.

The content of the glyoxal-based crosslinking agent (B) may be included in an amount of 30 to 70 parts by weight of the glyoxal-based crosslinking agent (B) based on 100 parts by weight of the solid content of the acetoacetyl group-modified polyvinyl alcohol-based resin (A) included in the solution A. there is. When the content of the glyoxal-based crosslinking agent (B) is less than the above range, there may be a problem in that the water resistance of the adhesive layer made of the adhesive composition including the glyoxal-based crosslinking agent (B) is lowered, and when it exceeds the above range , there may be a problem that the stability of the crude liquid is lowered.

In addition, according to an embodiment of the present invention, the content of the glyoxal-based crosslinking agent (B) is 6 parts by weight or more with respect to 100 parts by weight of the total acetoacetyl group-modified polyvinyl alcohol-based resin (A) included in the entire adhesive composition 20 It may be included in less than parts by weight. As such, the adhesive composition of the present invention has an advantage in that the adhesive strength or adhesion is more excellent despite the use of a rather small amount of the glyoxal-based crosslinking agent (B).

Water-soluble salts of polyvalent metal ions (C)

The adhesive composition of the present invention contains two or more types of water-soluble salts (C) of polyvalent metal ions, thereby enhancing the effect of the glyoxal-based crosslinking agent (B) to improve the degree of crosslinking of the adhesive composition including the same, as well as using the same This has the effect of improving the degree of crosslinking between the polarizer and the protective film to be adhered. That is, the adhesive composition of the present invention contains a water-soluble salt (C) of two or more types of polyvalent metal ions, so that a smaller amount of the glyoxal-based crosslinking agent (B) than when it contains a water-soluble salt (C) of one type of polyvalent metal ion In spite of including it, there is an advantage of better adhesion and water resistance. For this reason, it is possible to improve the adhesive strength and water resistance of the adhesive layer, and there is an effect that can also prevent the accompanying deterioration of optical durability.

The water-soluble salt (C) of the polyvalent metal ion may be specifically selected from the group consisting of zinc chloride, cobalt chloride, magnesium chloride, magnesium acetate, aluminum nitrate, zinc nitrate and zinc sulfate, zinc chloride having an excellent crosslinking catalyst role; More preferably, it is selected from the group consisting of zinc nitrate and aluminum nitrate.

When the water-soluble salt (C) of the polyvalent metal ion contains zinc chloride, the content thereof is 2 to 10 parts by weight based on 100 parts by weight of the solid content of the acetoacetyl group-modified polyvinyl alcohol-based resin (A) included in the solution B. It may be included in parts by weight. When the content of zinc chloride is less than the above range, a problem of insufficient water resistance of the adhesive layer made of the adhesive composition containing zinc chloride may occur. there is.

When the water-soluble salt (C) of the polyvalent metal ion contains zinc nitrate or aluminum nitrate, the content is 30 parts by weight based on 100 parts by weight of the solid content of the acetoacetyl group-modified polyvinyl alcohol-based resin (A) contained in the solution B. to 90 parts by weight. When the content of the zinc nitrate to aluminum nitrate is less than the above range, there may be a problem that the water resistance of the adhesive layer made of the adhesive composition containing the zinc nitrate to aluminum nitrate is insufficient, and when it exceeds the above range, crude liquid stability is There may be problems with degradation.

alcohol (D)

By including the alcohol (D), the adhesive composition of the present invention improves the spreadability of the adhesive composition comprising the same, so that the surface contact angle of the adhesive composition with respect to the substrate is reduced, thereby suppressing the generation of bubbles, and may occur when the adhesive composition is applied. There is an advantage in that the spreadability of the adhesive composition around the foreign material is also improved and the refractive index difference is reduced when the foreign material is mixed.

Specifically, the alcohol (D) may be a primary alcohol to a tertiary alcohol, and methanol, ethanol, n-propanol, i-propanol in consideration of compatibility and drying temperature with each component included in the adhesive composition , t-butanol, allyl alcohol, etc. are preferably used, and among them, it is most preferable to use ethanol in consideration of human safety and drying temperature in the polarizing plate process.

The content of the alcohol (D) is included in each of the solutions A to B in an amount of 30 to 260 parts by weight based on 100 parts by weight of the solid content of the acetoacetyl group-modified polyvinyl alcohol-based resin (A) included in each of the solutions A and B. can When the content of the alcohol (D) is less than the above range, the spreadability improvement effect is insignificant and the contact angle to the substrate may not be reduced. By increasing the viscosity of the adhesive composition, a problem in which crude liquid stability is lowered may occur.

The viscosity at 20°C of the adhesive composition of the present invention is preferably within the range of 3 to 25 mPa·sec. When the viscosity of the adhesive composition is less than 3 mPa sec, the water resistance of the adhesive layer made of the adhesive composition cannot be sufficiently expressed, and when the viscosity exceeds 25 mPa sec, the optical properties of the polarizing plate including the adhesive layer are lowered There is a problem that

The adhesive composition may further include additives such as a plasticizer, a silane coupling agent, an antistatic agent, fine particles, and a leveling agent in a range that does not impair the effects of the present invention.

The form of the adhesive composition is not particularly limited, but in order to form a uniform adhesive layer on the surface of a polarizer or a protective film as an adherend, it is preferably in a liquid form. As such a liquid adhesive, a solution type or dispersion type of various solvents can be used, and a solution type is preferable in consideration of the coatability of the substrate, and a solution type or dispersion type using water as a solvent is suitable in consideration of stability. .

Another aspect of the present invention is a polarizing plate made of the adhesive composition and an image display device including the same.

<Polarizer>

The polarizing plate of the present invention may be one in which a protective film is laminated together with an adhesive layer made of the adhesive composition of the present invention on at least one surface of a polarizer (polarizing film).

polarizer (Polarizing film)

The polyvinyl alcohol-type resin for forming a polarizer can be obtained by saponifying polyvinyl acetate-type resin. Examples of the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and a copolymer of vinyl acetate and another monomer copolymerizable therewith. Examples of the other monomer copolymerized with vinyl acetate include unsaturated carboxylic acids, unsaturated sulfonic acids, olefins, vinyl ethers, and acrylamides having an ammonium group. The degree of saponification of the polyvinyl alcohol-based resin is usually 85 to 100 mol%, preferably 98 mol% or more. This polyvinyl alcohol-type resin may be further modified|denatured, for example, polyvinyl polymer modified with aldehydes, polyvinyl acetal, etc. can be used. The average degree of polymerization of the polyvinyl alcohol-based resin constituting the polarizer is usually 1,000 to 10,000, preferably 1,500 to 5,000.

What formed such a polyvinyl alcohol-type resin into a film (polyvinyl alcohol-type resin film) into a film is used for the raw film of a polarizer. The method of forming a polyvinyl alcohol-type resin into a film is not specifically limited, A well-known film forming method is employable. Although the film thickness of the polyvinyl alcohol-type resin film used as a master is not specifically limited, For example, it may be 10-150 micrometers.

The polarizer is usually a step of uniaxially stretching a polyvinyl alcohol-based resin film that becomes such a master, a step of dyeing a polyvinyl alcohol-based resin film with a dichroic dye to adsorb the dichroic dye, and a polyvinyl having a dichroic dye adsorbed thereon. It may be manufactured by a method including a process of treating an alcohol-based resin film with an aqueous boric acid solution, and a process of washing with water after treatment with the aqueous boric acid solution.

Uniaxial stretching may be performed before dyeing|staining, may be performed simultaneously with dyeing|staining, and may be performed after dyeing|staining. When performing uniaxial stretching after dyeing|staining, uniaxial stretching may be performed before a boric-acid process, may be performed during a boric-acid process, and may be performed after a boric-acid process. Of course, it is also possible to perform uniaxial stretching in these plurality of steps. In uniaxial stretching, a raw film may be uniaxially stretched between different rolls, and may be uniaxially stretched using a hot roll. Moreover, dry stretching, such as extending|stretching in air|atmosphere, may be sufficient, and wet extending|stretching in which extending|stretching is performed in the state made it swollen with a solvent may be sufficient. The draw ratio is usually 3 to 8 times.

In order to dye a polyvinyl alcohol-type resin film with a dichroic dye, the polyvinyl alcohol-type resin film can be immersed in the aqueous solution containing a dichroic dye, for example. Specifically, as the dichroic dye, iodine or dichroic dye can be used. Further, the polyvinyl alcohol-based resin film is preferably immersed in water before the dyeing treatment.

When using iodine as a dichroic dye, the method of immersing and dyeing a polyvinyl alcohol-type resin film in the aqueous solution containing iodine and potassium iodide is usually adopted. The content of iodine in this aqueous solution is usually 0.01 to 1 part by weight per 100 parts by weight of water, and the content of potassium iodide is usually 0.5 to 20 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution used for dyeing is 20-40 degreeC normally, and the immersion time to this aqueous solution is 20-1800 second normally.

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 a water-soluble dichroic dye is usually employ|adopted. Content of the dichroic dye in this aqueous solution is 1x10 ^-4 to 10 weight part normally per 100 weight part of water, Preferably it is 1x10 ^-3 to 1 weight part. 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 20-80 degreeC normally, and the immersion time with respect to this aqueous solution is 10-1,800 second normally.

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

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

In this way, the polyvinyl alcohol-type resin film is uniaxially stretched, dyeing|staining by a dichroic dye, and a boric acid process are given, and a polarizer is obtained. The thickness of this polarizer is in the range of 5-40 micrometers normally, Preferably it exists in the range of 10-35 micrometers.

protective film

As the protective film, various transparent resin films such as a cellulose-based resin film, a cycloolefin-based resin film, an acrylic resin film, and a polyester-based resin film can be used specifically.

When using a cellulose-based resin film as the protective film, it is preferable that at least a part of cellulose is an esterified cellulose acetate-based resin. For example, triacetyl cellulose, diacetyl serolose, cellulose acetate propionate, etc. are mentioned.

The cycloolefin-based resin is, for example, a thermoplastic resin having a cycloolefin monomer unit such as norbornene or a polycyclic norbornene-based monomer, and a ring-opened polymer of the cycloolefin or a ring-opened copolymer using two or more types of cycloolefins. It may be a hydrogenated product, but may be an addition copolymer of a cycloolefin and an aromatic compound having a chain olefin or a vinyl group. Further, a polar group may be introduced into the cycloolefin-based resin.

The bonding method of the polarizer and the protective film using the adhesive composition is not particularly limited, for example, the polarizer and/or the protective film by a casting method, a Mayer bar coating method, a gravure coating method, a die coating method, an immersion coating method, a spraying method, etc. A method of applying an adhesive composition to the adhesive surface of The said casting method is a method of apply|coating an adhesive composition to the surface, while moving the polarizer or protective film which is a to-be-coated object in a mostly vertical direction, a mostly horizontal direction, or the diagonal direction between both.

After applying the adhesive composition, the polarizer and the protective film are sandwiched and bonded by a nip roll.

In addition, in order to improve the adhesiveness, the surface of the polarizer and/or the protective film may be appropriately subjected to surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, frame treatment, and saponification treatment. As said saponification process, the method of immersing in the aqueous solution of alkalis, such as sodium hydroxide and potassium hydroxide, is mentioned.

After laminating a polarizer and a protective film, a drying process is performed. The drying treatment is performed, for example, by spraying hot air, but the temperature at that time is appropriately selected in the range of 50 to 100°C. The drying time is usually 30 to 1,000 seconds.

<Image display device>

Another aspect of the present invention is an image display device provided with the above-described polarizing plate.

The image display device of the present invention includes the polarizing plate, and specific examples thereof include, but are not limited to, a liquid crystal display, an OLED, a flexible display, and the like.

Hereinafter, preferred examples are presented to help the understanding of the present invention, but the following examples are merely illustrative of the present invention, and it will be apparent to those skilled in the art that various changes and modifications are possible within the scope and spirit of the present invention, It goes without saying that such variations and modifications fall within the scope of the appended claims. In the following Examples and Comparative Examples, "%" and "part" indicating the content are by weight unless otherwise specified.

production example

production example One. polarizer Produce

A 75 μm thick polyvinyl alcohol film with an average degree of polymerization of 2,400 and a saponification degree of 99.9 mol% or more was uniaxially stretched to about 5 times in a dry manner, and immersed in water (distilled water) at 60° C. for 1 minute while maintaining the stretched state. After that, the iodine/potassium iodide/distilled water weight ratio was 0.05/5/100 and immersed in an aqueous solution at 28° C. for 60 seconds. Thereafter, the mixture was immersed in an aqueous solution at 72° C. with a weight ratio of potassium iodide/boric acid/distilled water of 8.5/8.5/100 for 300 seconds, washed with distilled water at 26° C. for 20 seconds, and dried at 65° C. to add iodine to the PVA-based film. An adsorption-oriented polarizer was prepared.

production example 2. Manufacture of protective film

A triacetyl cellulose-based film, KC8UX (Konica, T), was used after saponification.

production example 3. Preparation of adhesive composition ( 2-component )

Preparation of composition A: An aqueous solution with a solid content of 3.8% was prepared by dissolving an acetoacetyl group-modified polyvinyl alcohol-based resin (Cosenol Z200, Nippon Synthetic Chemical Industry Co., Ltd.) with a saponification degree of 99.2 mol% in water (distilled water). prepared. An adhesive solution A composition was prepared by adding a 40% aqueous solution of a glyoxal crosslinking agent (Daejeonghwageum) and alcohol to the aqueous solution according to the contents shown in Table 1 below and mixing them.

Preparation of solution B composition: An aqueous solution having a solid content of 3.8% by weight by dissolving an acetoacetyl group-modified polyvinyl alcohol-based resin (Cosenol Z200, Nippon Synthetic Chemical Industry Co., Ltd.) having a saponification degree of 99.2 mol% in water (distilled water) was prepared. Zinc chloride (Daejeong Hwageum), zinc nitrate (Daejeong Hwageum), or aluminum nitrate (Aldrich Co.) and alcohol as water-soluble salts of polyvalent metal ions in the aqueous solution are added as shown in Table 2 below, and then mixed to form Adhesive B solution A composition was prepared.

An adhesive composition was prepared by mixing the composition A and the composition B prepared above at room temperature and stirring for about 30 minutes. At this time, the mixing ratio of the liquid A and the liquid B is described in Table 3.

production example 4. Preparation of adhesive composition ( 1-component )

Preparation Example 4-1. Preparation of the adhesive composition of Comparative Example 13

Acetoacetyl group-modified polyvinyl alcohol-based resin (Z200, Nippon Synthetic Chemical Industry Co., Ltd., average degree of polymerization 1200) having a saponification degree of 99.2 mol% was dissolved in distilled water to modify acetoacetyl group of 6% by weight based on the solid content of the adhesive composition Polyvinyl alcohol was added.

The acetoacetyl group-modified polyvinyl alcohol-based resin aqueous solution and glyoxal (40% aqueous solution, Daejeonghwageum), which is a crosslinking agent, are mixed so as to be 10 parts by weight based on 100 parts by weight of the acetoacetyl group-modified polyvinyl alcohol-based resin, and polyvalent An adhesive composition was prepared by mixing zinc chloride (Daejeong Hwageum) as a water-soluble salt of metal ions so as to be 10 parts by weight based on 100 parts by weight of an acetoacetyl group-modified polyvinyl alcohol-based resin.

Preparation Example 4-2. Preparation of the adhesive composition of Comparative Example 14

By dissolving an acetoacetyl group-modified polyvinyl alcohol-based resin having a saponification degree of 99.2 mol% (Z200, Nippon Synthetic Chemical Industry Co., Ltd., average degree of polymerization 1200) in distilled water, 6% by weight of acetoacetyl group modification based on the solids weight of the adhesive composition Polyvinyl alcohol was added.

The acetoacetyl group-modified polyvinyl alcohol-based resin aqueous solution and glyoxal (40% aqueous solution, Daejeong Hwageum), which is a crosslinking agent, are mixed so as to be 15 parts by weight based on 100 parts by weight of the acetoacetyl group-modified polyvinyl alcohol-based resin, and polyvalent An adhesive composition was prepared by mixing zinc chloride (Daejeong Hwageum) as a water-soluble salt of metal ions so as to be 5 parts by weight based on 100 parts by weight of an acetoacetyl group-modified polyvinyl alcohol-based resin.

Example 1 to 17 and comparative example 1 to 14: Preparation of a polarizing plate

After applying the adhesive composition prepared by the method of Preparation Example 3 to both sides of the polarizer prepared in Preparation Example 1 at the content shown in Tables 1 and 2 below, the protective film of Preparation Example 2 was applied with a nip roll. and joined. The bonded polarizing plate was dried in a hot air dryer at 80° C. for 5 minutes to prepare a polarizing plate. In the case of the adhesive composition (Comparative Examples 13 and 14) prepared in Preparation Example 4, a polarizing plate was prepared in the same manner as above.

(Unit: parts by weight) Composition A aceto
acetyl group
modified polyvinyl
alcoholic
Resin (solid content) glyoxal
(solid content) methanol ethanol n-propanol i-propanol t-butanol Example 1 100 20 30 - - - - Example 2 100 20 90 - - - - Example 3 100 20 150 - - - - Example 4 100 20 200 - - - - Example 5 100 20 260 - - - - Example 6 100 30 - 200 - - - Example 7 100 30 - - 200 - - Example 8 100 30 - - - 200 - Example 9 100 30 - - - - 200 Example 10 100 50 200 - - - - Example 11 100 70 200 - - - - Example 12 100 50 200 - - - - Example 13 100 50 200 - - - - Example 14 100 50 200 - - - - Example 15 100 50 200 - - - - Example 16 100 50 200 - - - - Example 17 100 50 200 - - - - Comparative Example 1 100 20 - - - - - Comparative Example 2 100 30 - - - - - Comparative Example 3 100 50 - - - - - Comparative Example 4 100 70 - - - - - Comparative Example 5 100 50 - - - - - Comparative Example 6 100 50 - - - - - Comparative Example 7 100 50 - - - - - Comparative Example 8 100 50 - - - - - Comparative Example 9 100 50 - - - - - Comparative Example 10 100 50 - - - - - Comparative Example 11 100 70 200 - - - - Comparative Example 12 100 50 200 - - - -

(Unit: parts by weight) Composition B aceto
acetyl group
Modified polyvinyl
alcoholic
Resin (solid content) zinc chloride
(solid content) zinc nitrate
(solid content) nitric acid
aluminum
(solid content) methanol ethanol n-propanol i-
propanol t-butanol Example 1 100 2 30 - 30 - - - - Example 2 100 2 30 - 90 - - - - Example 3 100 2 30 - 150 - - - - Example 4 100 2 30 - 200 - - - - Example 5 100 2 30 - 260 - - - - Example 6 100 2 30 - - 200 - - - Example 7 100 2 30 - - - 200 - - Example 8 100 2 30 - - - - 200 - Example 9 100 2 30 - - - - - 200 Example 10 100 2 30 - 200 - - - - Example 11 100 2 30 - 200 - - - - Example 12 100 5 30 - 200 - - - - Example 13 100 8 30 - 200 - - - - Example 14 100 5 20 - 200 - - - - Example 15 100 5 50 - 200 - - - - Example 16 100 5 90 - 200 - - - - Example 17 100 5 - 50 200 - - - - Comparative Example 1 100 2 30 - - - - - - Comparative Example 2 100 2 30 - - - - - - Comparative Example 3 100 2 30 - - - - - - Comparative Example 4 100 2 30 - - - - - - Comparative Example 5 100 5 30 - - - - - - Comparative Example 6 100 8 30 - - - - - - Comparative Example 7 100 5 20 - - - - - - Comparative Example 8 100 5 50 - - - - - - Comparative Example 9 100 5 90 - - - - - - Comparative Example 10 100 5 - 50 - - - - - Comparative Example 11 100 5 - - 200 - - - - Comparative Example 12 100 - 50 - 200 - - - -

Experimental example 1. Adhesion evaluation (Cutter evaluation)

Adhesion evaluation was performed for Examples 1 to 17 and Comparative Examples 1 to 14. After the prepared polarizing plate was left at room temperature for 1 hour, the cutter blade was placed between each film of the polarizing plate (between the polarizer and the polarizer protective film), and the method of inserting the blade when the blade was pushed is as follows. was evaluated, and the results are shown in Table 3 below.

<Evaluation criteria>

(double-circle): The blade of a cutter does not enter between any films.

○: When the blade is pushed forward, it stops when the blade enters 1 to 2 mm between at least one of the films.

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

x: When the blade is pushed forward, the blade enters between at least one of the films without unreasonableness.

Experimental example 2. Water resistance evaluation

Water resistance was evaluated for Examples 1 to 17 and Comparative Examples 1 to 14.

For each polarizing plate left to stand for 24 hours under an environment of 23° C. and 55% relative humidity, a water resistance test was performed as follows to evaluate water resistance.

With the absorption axis of the polarizing plate as the long side, the polarizing plate was cut into a size of 5 × 2 cm as a sample, and the dimension in the long side direction was accurately measured. At this time, the sample exhibits a unique color uniformly over the entire surface due to the iodine adsorbed to the polarizing film. 2 is a view schematically showing a water resistance evaluation method, (C) shows a sample before hot water immersion (a), (D) shows a sample after hot water immersion (a). As shown in Fig. 2 (C), one short side of the sample was gripped with a gripper (d), and about 80% of the length in the longitudinal direction was immersed in a water bath at 60°C and maintained for 8 hours. Thereafter, the sample (a) was taken out of the water bath and the moisture was wiped off.

The polarizer (c) of the polarizing plate shrinks by immersion in hot water as described above. The degree of shrinkage of the polarizer (c) was evaluated by measuring the distance from the end portion 1a (end of the protective film) at the center of the short side of the sample (a) to the end of the polarizer (c) contracted to determine the shrinkage length. . In addition, as shown in Fig. 2 (D), the polarizer (c) positioned at the center of the polarizing plate is contracted by immersion in warm water, so that iodine is eluted from the periphery of the polarizer (c) between the protective films, and the sample (a) ), a color missing part (b) is formed on the periphery. The degree of discoloration was evaluated by measuring the distance from the distal end of the contracted polarizer (c) in the center of the short side of the sample (a) to the region where the characteristic color of the polarizing plate remained, and it was set as the length without iodine. The sum of the shrinkage length and the length without iodine was defined as the total erosion length Y. The total erosion length Y is the distance from the edge part 1a of the sample (a) in the center of the short side of the sample (a) to the area|region where the color peculiar to a polarizing plate remains. It can be judged that the smaller the shrinkage length, the length without iodine, and the total erosion length Y, the higher the adhesiveness in the presence of water. The total erosion length Y was evaluated in the following 4 steps, and the results are shown in Table 3 below.

<Evaluation criteria>

◎: Total erosion length Y is less than 0.1 mm

○: Total erosion length Y is 0.1 mm or more and less than 0.5 mm

△: Total erosion length Y is 0.5 mm or more and less than 2 mm

×: the total erosion length Y is 2 mm or more

Experimental example 3. Transmittance, polarization ( % )

Transmittance and polarization degree of Examples 1 to 17 and Comparative Examples 1 to 14 were measured.

The prepared polarizing plate was cut to a size of 4 cm × 4 cm to prepare a specimen, and after attaching the specimen to a measuring holder, it was measured using an ultraviolet and visible light spectrometer (V-7100, manufactured by JASCO), and the results are shown in Table 3 described in.

Experimental example 4. contact angle (°)

Contact angles for Examples 1 to 17 and Comparative Examples 1 to 14 were measured.

The aqueous adhesive solution prepared above was dropped on the surface of the polarizer prepared in Preparation Example 1 to measure the contact angle of the adhesive to the polyvinyl alcohol-based film, and it was determined that the lower the contact angle, the better the spreadability. The contact angle measurement results are shown in Table 3.

Experimental example 5. Foreign object visibility evaluation

Foreign object visibility was measured for Examples 1 to 17 and Comparative Examples 1 to 14.

An inorganic bead having a distribution of 80 μm to 120 μm was applied to the surface of the polarizer prepared in Preparation Example 1 to make a foreign material, and then using the aqueous adhesive solution of Examples 1 to 17 and Comparative Examples 1 to 12 A polarizing plate was manufactured. After that, one of the polarizing plates of Examples 1 to 17 and Comparative Examples 1 to 12 prepared above is rotated 90° and placed on the backlight on one normal polarizing plate in a dark room, and the size of the light leakage generating part due to foreign matter is measured, and the The results are shown in Table 3 below, and it was judged that as the size of the light leakage was smaller, the foreign matter visibility was reduced.

<Evaluation criteria>

○ : Light leakage size less than 130㎛

△ : Light leakage size 130㎛ or more and less than 150㎛

× : Light leakage size 150㎛ or more

mixing ratio
(A liquid: B liquid) adhesion water resistance transmittance Polarization degree Contact angle (°) alien substance
visibility Example 1 1:1 ◎ ○ 43.1 99.996 47 △ Example 2 1:1 ◎ ○ 43 99.996 47 △ Example 3 1:1 ◎ ○ 43.2 99.996 43 ○ Example 4 1:1 ◎ ○ 43.1 99.997 42 ○ Example 5 1:1 ◎ ○ 43.2 99.996 40 ○ Example 6 1:1 ◎ ◎ 43.2 99.997 41 ○ Example 7 1:1 ◎ ◎ 43.2 99.997 42 ○ Example 8 1:1 ◎ ◎ 43.1 99.996 42 ○ Example 9 1:1 ◎ ◎ 43.2 99.997 43 ○ Example 10 1:1 ◎ ◎ 43.3 99.996 43 ○ Example 11 1:1 ◎ ◎ 43.3 99.996 43 ○ Example 12 1:1 ◎ ◎ 43.3 99.996 42 ○ Example 13 1:1 ◎ ◎ 43.1 99.996 43 ○ Example 14 1:1 ◎ ○ 43 99.997 41 ○ Example 15 1:1 ◎ ◎ 43.1 99.996 42 ○ Example 16 1:1 ◎ ◎ 43.2 99.996 44 ○ Example 17 1:1 ◎ ◎ 43.1 99.995 41 ○ Example 18 0.5:1 ○ ○ 42.9 99.995 45 △ Example 19 1.5:1 ◎ ○ 43.1 99.995 47 ○ Example 20 1:0.5 ○ ○ 43 99.996 45 △ Example 21 1:1.5 ◎ ○ 43.2 99.995 47 ○ Comparative Example 1 1:1 ◎ ○ 43.5 99.991 49 × Comparative Example 2 1:1 ◎ ◎ 43.3 99.992 50 × Comparative Example 3 1:1 ◎ ◎ 43.3 99.990 52 × Comparative Example 4 1:1 ◎ ◎ 43.3 99.991 52 × Comparative Example 5 1:1 ◎ ◎ 43.4 99.990 50 × Comparative Example 6 1:1 ◎ ◎ 43.3 99.989 51 × Comparative Example 7 1:1 ◎ ○ 43.2 99.991 50 × Comparative Example 8 1:1 ◎ ◎ 43.3 99.992 50 × Comparative Example 9 1:1 ◎ ◎ 43.4 99.991 52 × Comparative Example 10 1:1 ◎ ◎ 43.3 99.990 50 × Comparative Example 11 1:1 ◎ △ 43.1 99.995 42 ○ Comparative Example 12 1:1 × △ 43.2 99.996 43 ○ Comparative Example 13 1:1 ○ × 43.1 99.990 51 × Comparative Example 14 1:1 ○ × 42.9 99.991 50 ×

Referring to Table 3 above, in the case of the adhesive composition of the present invention comprising two or more water-soluble salts of polyvalent metal ions and alcohol together (Examples 1 to 21), the conventional method comprising one water-soluble salt of polyvalent metal ions In the case of a polarizing plate using the adhesive composition of (Comparative Examples 11 to 14), it was confirmed that both adhesion and water resistance were excellent, and the contact angle was reduced compared to the case that did not contain alcohol (Comparative Examples 1 to 10, 13 and 14). It was confirmed that visibility was also improved. In addition, as in Comparative Examples 13 and 14, when only one water-soluble salt of a polyvalent metal ion was included, it was confirmed that water resistance was lowered when less than 20 parts by weight of the glyoxal crosslinking agent was included.

00: light
10: polarizer
20: Adhesive composition containing alcohol
21: alcohol-free adhesive composition
30: foreign body
X, X': Visibility of foreign objects
a: sample
1a: distal end
b: periphery (color loss)
c: polarizer
d: phage
Y: total erosion length

Claims (12)

In the adhesive composition comprising an acetoacetyl group-modified polyvinyl alcohol-based resin, a glyoxal-based crosslinking agent, a water-soluble salt of two or more polyvalent metal ions, and an alcohol,
The adhesive composition is A solution comprising an acetoacetyl group-modified polyvinyl alcohol-based resin, a glyoxal-based crosslinking agent and alcohol; and liquid B containing an acetoacetyl group-modified polyvinyl alcohol-based resin, a water-soluble salt of two or more polyvalent metal ions, and an alcohol;
Adhesive composition, characterized in that the content of the glyoxal-based crosslinking agent is 6 parts by weight or more and less than 20 parts by weight based on 100 parts by weight of the total acetoacetyl group-modified polyvinyl alcohol-based resin contained in the adhesive composition. The method of claim 1,
The mixing ratio of the solution A to the solution B is 1:0.5 to 1:1.5 based on the weight of the solid content of the acetoacetyl group-modified polyvinyl alcohol-based resin included in each adhesive composition. According to claim 1,
The acetoacetyl group-modified polyvinyl alcohol-based resin contained in the solution A is an adhesive composition, characterized in that it is included in an amount of 20 to 80 parts by weight based on 100 parts by weight of the total solution A. According to claim 1,
The acetoacetyl group-modified polyvinyl alcohol-based resin contained in the B solution is an adhesive composition, characterized in that it is included in an amount of 15 to 70 parts by weight based on 100 parts by weight of the total B solution. According to claim 1,
The alcohol is an adhesive composition comprising at least one selected from the group consisting of methanol, ethanol, n-propanol, i-propanol and t-butanol. The method of claim 1,
The alcohol contained in each of the solutions A to B is included in an amount of 30 to 260 parts by weight based on 100 parts by weight of the solid content of the acetoacetyl group-modified polyvinyl alcohol-based resin contained in each of the solutions A to B. According to claim 1,
The adhesive composition, characterized in that the average degree of polymerization of the acetoacetyl group-modified polyvinyl alcohol-based resin is 100 to 1500. According to claim 1,
The water-soluble salt of the polyvalent metal ion is an adhesive composition, characterized in that it comprises two or more selected from the group consisting of zinc chloride, zinc nitrate and aluminum nitrate. The method of claim 1,
The water-soluble salt of the polyvalent metal ion includes two or more selected from the group consisting of zinc chloride, zinc nitrate and aluminum nitrate,
The content of the zinc chloride is an adhesive composition, characterized in that it is contained in an amount of 2 to 10 parts by weight based on 100 parts by weight of the total solid content of the acetoacetyl group-modified polyvinyl alcohol-based resin contained in the liquid B. The method of claim 1,
The water-soluble salt of the polyvalent metal ion includes two or more selected from the group consisting of zinc chloride, zinc nitrate and aluminum nitrate,
The content of the zinc nitrate to aluminum nitrate is an adhesive composition, characterized in that it is included in an amount of 30 to 90 parts by weight based on 100 parts by weight of the total solid content of the acetoacetyl group-modified polyvinyl alcohol-based resin contained in the solution B. A polarizing plate comprising an adhesive layer made of the adhesive composition according to any one of claims 1 to 10. An image display device comprising the polarizing plate of claim 11 .

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