KR20150042328A - Adhesive composition for polarizing plate - Google Patents

Abstract

The present invention relates to an adhesive composition for a polarizing plate and, more specifically, to an adhesive composition for a polarizing plate which is capable of remarkably improving a polarizing plate manufacturing yield since long curing time is not required in order to have sufficient adhesion by noticeably improving the hardening rate via inclusion of photopolymerizable compounds and radical photoinitiators, wherein the photopolymerizable compounds contain at least one compound among a compound represented by chemical formula 1 and a compound represented by chemical formula 2, and an acrylic compound.

Description

Adhesive composition for polarizing plate < RTI ID = 0.0 >

The present invention relates to an adhesive composition for a polarizing plate.

Polarizing plates used in various image display devices such as a liquid crystal display (LCD), an electroluminescence (EL) display, a plasma display (PDP), a field emission display (FED) and an OLED are generally made of polyvinyl alcohol alcohol, PVA) film comprises a polarizer in which an iodine compound or a dichroic polarizing material is adsorbed and oriented, a polarizer protective film is laminated on one side of the polarizer, and a polarizer protective film, a liquid crystal cell Layer structure in which a pressure-sensitive adhesive layer and a release film are laminated in this order.

For the lamination of the polarizer and the protective film, an adhesive is used. In the case of the photo-curable adhesive generally used, the curing speed is slow, and a curing process for a long time is required in order to exhibit sufficient adhesive force after bonding. As a result, there is a problem that the process time required for the production of the polarizing plate, the temperature for the curing process, and the cost for the humidity control increase. In addition, storage and handling problems during the curing process may also occur.

In addition, in recent years, various image display devices have become larger and larger, and polarizers and polarizing plates to be used are also becoming larger. Therefore, the handling becomes more disadvantageous in the handling process in the process, and the amount of deformation generated under repeated high temperature and low temperature environments during use is further increased, and a polarizing plate excellent in environmental resistance is required.

The polarizer and the protective film are bonded together by an adhesive interposed therebetween. When the adhesion between the polarizer and the protective film is poor, deformation may occur during handling or use during processing. When the film is exposed to a long- A phenomenon may occur. Therefore, the adhesive plays an important role in the durability of the polarizing plate.

Accordingly, there is a need to develop an adhesive composition that can improve the curing rate and shorten the curing process time, and is excellent in environmental resistance.

Korean Patent Publication No. 2006-26007 discloses an adhesive for a polarizing plate, a polarizing plate, a manufacturing method thereof, an optical film, and an image display device.

Korea Patent Publication No. 2006-26007

An object of the present invention is to provide an adhesive composition for a polarizing plate in which the curing rate is remarkably improved.

An object of the present invention is to provide an adhesive composition for a polarizing plate which is excellent in adhesion and water resistance.

It is an object of the present invention to provide a polarizing plate bonded with the above adhesive composition.

1. A composition comprising a photopolymerizable compound and a radical photoinitiator,

Wherein the photopolymerizable compound comprises at least one compound of the following general formulas (1) and (2) and an acrylic compound:

[Chemical Formula 1]

(Wherein R represents a hydrogen atom, a linear or branched alkyl group having 1 to 20 carbon atoms which is substituted or unsubstituted with an alkoxy group having 1 to 5 carbon atoms, an isocyanurate group,

,

, or

ego,

m is an integer from 1 to 8;

R ₁ is an alkylene group having 1 to 5 carbon atoms;

n is an integer of 1 to 4)

(2)

(Wherein R is a straight or branched alkyl group having 1 to 20 carbon atoms which is substituted or unsubstituted with a hydrogen atom or an alkoxy group having 1 to 5 carbon atoms;

R ₁ is an alkylene group having 1 to 5 carbon atoms;

and n is an integer of 1 to 4).

2. The compound according to item 1 above, wherein the compound of formula 1 or 2 is selected from the group consisting of beta-mercaptopropionic acid, methyl-3-mercaptopropionate, 2-ethylhexyl-3-mercaptopropionate, Mercaptopropionate, mercaptopropionate, methoxybutyl-3-mercaptopropionate, stearyl-3-mercaptopropionate, trimethylolpropane tris (3-mercaptopropionate) (3-mercaptopropionate), and tetraethyleneglycol bis (3-mercaptopropionate). The adhesive for polarizing plate according to claim 1, wherein the adhesive is at least one selected from the group consisting of poly Composition.

3. The adhesive composition for a polarizer according to 1 above, wherein the compound of the general formulas (1) and (2) is contained in an amount of 1 to 20% by weight based on the total weight of the composition.

4. The composition of claim 1, wherein the acrylic compound is selected from the group consisting of N-methyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N- (Meth) acrylamide, N-methylol (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, N-methylol- (Meth) acrylate, aminomethyl (meth) acrylamide, aminoethyl (meth) acrylamide, mercaptomethyl (meth) acrylamide, 2-hydroxy- methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, 2-hydroxypropyl Acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) (Meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, 2-hydroxyethyl Wherein the adhesive composition is at least one selected from the group consisting of hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate and 8-hydroxyoctyl (meth) acrylate.

5. The adhesive composition for a polarizing plate according to item 1, wherein the radical photoinitiator is at least one selected from the group consisting of a carbonyl photoinitiator, a benzoin ether photoinitiator, and an acetophenone photoinitiator.

6. The adhesive composition for a polarizing plate according to item 1 above, further comprising a crosslinking agent.

7. A polarizing plate on which at least one surface of a polarizer is bonded with a protective film for an adhesive composition for a polarizing plate according to any one of 1 to 6 above.

The adhesive composition for a polarizing plate of the present invention has a remarkably improved curing speed and does not require curing for a long time in order to exhibit sufficient adhesion. Accordingly, the time required for the production of the polarizing plate is remarkably shortened and the process yield can be improved.

The adhesive composition for a polarizing plate of the present invention is excellent in adhesion and water resistance. Accordingly, the durability of the polarizing plate can be remarkably improved.

The present invention includes a photopolymerizable compound and a radical photoinitiator, wherein the photopolymerizable compound contains at least one of the compounds represented by formulas (1) and (2) and an acrylic compound, thereby significantly improving the curing rate and requiring a long period of curing And thus can remarkably improve the yield of polarizing plate production.

Hereinafter, the present invention will be described in detail.

Usually, the polarizing plate includes a polarizer and a protective film adhered to one or both sides thereof with an adhesive. Since the photocurable adhesive composition used at this time has a slow curing speed, it takes a long time to develop the initial adhesion force, which is a time until a sufficient adhesive force is exhibited, and usually requires aging more than 24 hours after the bonding. As a result, the time required for producing the polarizing plate is increased, and the yield of the process is lowered, resulting in storage or handling problems.

However, the curing speed of the adhesive composition for a polarizing plate of the present invention is remarkably improved, and sufficient adhesion can be exhibited in a short time without curing for a long time. Thus, the yield of polarizing plate production can be remarkably improved.

< For polarizer  Adhesive composition>

The adhesive composition of the present invention comprises a photopolymerizable compound and a radical photoinitiator.

Photopolymerization  compound

The photopolymerizable compound is a component having a binder function and imparting adhesiveness.

The photopolymerizable compound according to the present invention comprises at least one compound of the following general formulas (1) and (2) and an acrylic compound:

[Chemical Formula 1]

(Wherein R represents a hydrogen atom, a linear or branched alkyl group having 1 to 20 carbon atoms which is substituted or unsubstituted with an alkoxy group having 1 to 5 carbon atoms, an isocyanurate group,

,

, or

ego,

m is an integer from 1 to 8;

R ₁ is an alkylene group having 1 to 5 carbon atoms;

n is an integer of 1 to 4)

(2)

(Wherein R is a straight or branched alkyl group having 1 to 20 carbon atoms which is substituted or unsubstituted with a hydrogen atom or an alkoxy group having 1 to 5 carbon atoms;

R ₁ is an alkylene group having 1 to 5 carbon atoms;

and n is an integer of 1 to 4).

The compounds of the formulas (1) and (2) can rapidly improve the curing rate because of the rapid radical generation during photo-curing. As a result, the initial cohesive force development time is shortened, and curing for a long time is not required for sufficient adhesion.

Further, the polarizer or the protective film is hydrogen-bonded to the polar group present on the surface to exhibit excellent adhesiveness, and the water resistance is improved to prevent the polarizing plate from being peeled under the humidifying heat condition.

The compounds of formulas (1) and (2) are not particularly limited and include, for example, beta-mercaptopropionic acid, methyl-3-mercaptopropionate, 2-ethylhexyl-3-mercaptopropionate, Mercaptopropionate, mercaptopropionate, methoxybutyl-3-mercaptopropionate, stearyl-3-mercaptopropionate, trimethylolpropane tris (3-mercaptopropionate) (3-mercaptopropionate), tetraethylene glycol bis (3-mercaptopropionate), and the like can be given. These may be used alone or in combination of two or more.

The content of the compounds of formulas (1) and (2) is not particularly limited and may be, for example, 1 to 20% by weight, preferably 3 to 15% by weight, of the total weight of the adhesive composition. If the content of the compounds of formulas (1) and (2) is less than 1% by weight, the effect of improving the curing rate may be insufficient. If the content of the compounds is more than 20% by weight, gelation of the adhesive composition may occur.

Acrylic compounds are used together with the compounds of formulas (1) and (2) to significantly improve adhesion and water resistance.

The acrylic compound of the present invention is not particularly limited and includes, for example, N-methyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, Propyl acrylamide, N-butyl (meth) acrylamide, N-hexyl (meth) acrylamide, N-methylol Propyl (meth) acrylamide, aminomethyl (meth) acrylamide, aminoethyl (meth) acrylamide, mercaptomethyl (meth) acrylamide, 2- (Meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, Butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) (Meth) acrylates such as nonyl (meth) acrylate, lauryl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (Meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate and 8-hydroxyoctyl Ethyl acrylate, 4-hydroxybutyl acrylate, 6-hydroxyhexyl acrylate, and 8-hydroxyoctyl acrylate. These may be used alone or in combination.

In the present invention, (meth) acrylate means acrylate or methacrylate.

The content of the acrylic compound is not particularly limited and may be, for example, from 60 to 95% by weight, and preferably from 65 to 95% by weight, of the total weight of the adhesive composition. When the content of the acrylic compound is less than 60% by weight, the adhesion improving effect may be insufficient. When the content is more than 95% by weight, the water resistance may be deteriorated.

Radical Photoinitiator

The radical photoinitiator is not particularly limited as long as it can polymerize the photopolymerizable compound, and a radical photoinitiator commonly used in the art can be used. Examples of the photoinitiator include a carbonyl photoinitiator, a benzoin ether photoinitiator, an acetophenone photoinitiator . These may be used alone or in combination of two or more.

Examples of commercially available products include darocur 1173, darocur 4265, darocur BP, darocur TPO, darocur MBF, irgacure 184, irgacure 500, irgacure 2959, irgacure 754, irgacure 651, irgacure 369, irgacure 907, irgacure 907, 1300, irgacure 819, irgacure 2022, irgacure 819DW, irgacure 2100, irgacure 784, irgacure 250, and the like. These may be used alone or in combination of two or more.

The content of the radical photoinitiator is not particularly limited and can be, for example, 0.1 to 10% by weight, preferably 0.5 to 5% by weight, based on the total weight of the adhesive composition. If the amount of the radical photoinitiator is less than 0.1% by weight, the adhesive composition may not be sufficiently cured. If the amount is more than 10% by weight, unreacted residual photoinitiator may cause yellowing of the adhesive layer.

Cross-linking agent

The adhesive composition of the present invention may further comprise a crosslinking agent for improving the reactivity of the curing reaction.

The type of the crosslinking agent is not particularly limited as long as it can improve the reactivity of the curing reaction between the siloxane-based compound substituted with an acrylic functional group and the acrylic photopolymerizable compound, and examples thereof include (meth) acrylate An acrylate-based compound containing two or more groups may be used.

A-NOD, A-DOD, A-NPG, A-200, A-400, A-600, APG-100, APG-400, APG -700, A-DCP, A-DOG, A-TMM, A-TMMT, A-DPH and A-TMPT. These may be used alone or in combination of two or more.

The content of the crosslinking agent is not particularly limited and can be, for example, 0.01 to 10% by weight, preferably 0.5 to 1% by weight, based on the total weight of the adhesive composition. When the content is less than 0.01% by weight, the effect of improving the reactivity may be insignificant. When the content is more than 10% by weight, the content of other components may be relatively decreased, and adhesiveness, water resistance at room temperature,

additive

If necessary, the adhesive composition for a polarizing plate of the present invention may further comprise an additive.

The kind of the additive is not particularly limited and includes, for example, a sensitizer, an adhesion promoter, a leveling agent, an ultraviolet absorber, an antioxidant, a dye, a processing aid, an ion trap agent, an antioxidant, a tackifier, a filler, Antistatic agents, aromatic agents, and the like. These may be used alone or in combination of two or more.

The content of the additive is not particularly limited and can be, for example, 0.01 to 3% by weight, preferably 0.5 to 1% by weight, based on the total weight of the adhesive composition.

<Polarizer>

The present invention also relates to a polarizing plate in which a protective film is bonded to at least one surface of a polarizer with an adhesive composition for a polarizing plate of the present invention.

A polarizer is one in which a dichroic dye is adsorbed and oriented on a stretched polyvinyl alcohol-based resin 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.

Such a polyvinyl alcohol-based resin film is used as the original film of the 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 uniaxial stretching of the polyvinyl alcohol film may be performed before dyeing, concurrently with dyeing, or may be performed after dyeing. If uniaxial stretching is carried out after dyeing, it may be carried out before the boric acid treatment, or may be carried out during the boric acid treatment. Of course, it is also possible to perform uniaxial stretching in a plurality of such steps. For uniaxial stretching, other rolls or rolls of different circumferences may be used. The uniaxial stretching may be either dry stretching in air or wet stretching in the state of being swollen with a solvent. The stretching ratio is usually 4 to 8 times.

As a step of dyeing a stretched polyvinyl alcohol film with a dichroic dye, for example, a method of immersing a polyvinyl alcohol film in an aqueous solution containing a dichroic dye can be used. As the 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 iodine is used as the dichroic dye, a method in which a polyvinyl alcohol-based film is dipped in an aqueous solution for dyeing usually containing iodine and potassium iodide may be used. 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 占 폚, and the immersion time (dyeing time) is usually 20 to 1,800 seconds.

When a dichroic dye is used as the dichroic dye, a method of dying and dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic dye is generally employed. 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. The aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing aid. The dye aqueous solution used for dyeing usually has a temperature of 20 to 80 DEG C, and the immersion time for this aqueous solution is usually 10 to 1,800 seconds.

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, it is preferable that the aqueous solution containing boric acid contains potassium iodide. The content thereof is usually 0.1 to 15 parts by weight, preferably 5 to 12 parts by weight per 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., and more preferably 60 to 80 ° C. The immersing time is usually 60 to 1,200 seconds, preferably 150 to 600 seconds, Preferably 200 to 400 seconds.

After the boric acid treatment, the polyvinyl alcohol film is usually washed with water and dried. The washing treatment can be carried out by immersing the boric acid-treated polyvinyl alcohol-based film in water. The water temperature of the water treatment is usually 5 to 40 占 폚, and the immersion time is usually 1 to 120 seconds. After washing with water, the polarizer can be obtained. The drying treatment can be usually carried out using a hot air dryer or a far infrared ray heater. The drying treatment temperature is usually 30 to 100 占 폚, preferably 50 to 80 占 폚, and the drying time is usually 60 to 600 seconds, preferably 120 to 600 seconds.

The thickness of the polarizer according to the present invention is not particularly limited, but may be, for example, 5 to 40 탆.

The kind of the protective film is not particularly limited as long as it is excellent in transparency, mechanical strength, thermal stability, moisture shielding property, isotropy, and the like. For example, the protective film is made of an acrylic resin film, a cellulose resin film, a polyolefin resin film and a polyester resin film Various transparent resin films containing at least one kind selected from the group consisting of

Specific examples of the protective film include acrylic resin films such as polymethyl (meth) acrylate and polyethyl (meth) acrylate; Polyester based resin films such as polyethylene terephthalate, polyethylene isophthalate, polyethylene naphthalate and polybutylene terephthalate; Cellulose-based resin films such as diacetylcellulose and triacetylcellulose; Polyolefin-based resin films such as polyethylene, polypropylene, cyclo-based or norbornene structures, polyolefin-based or ethylene-propylene copolymer; And the like, but the present invention is not limited thereto.

The thickness of the protective film is not particularly limited, but may be 10 to 200 占 퐉, preferably 10 to 150 占 퐉. When the thickness of the protective film is 10 to 200 탆, when the polarizer protective film is laminated on both sides of the polarizer, the respective protective films may have the same or different thicknesses.

The adhesive composition for a polarizing plate according to the present invention may be applied to at least one surface of the polarizer to form an adhesive layer, and the polarizer and the protective film or adhesive layer may be bonded to each other via the adhesive layer.

The thickness of the adhesive layer formed by applying the adhesive composition of the present invention is not particularly limited, but it may be usually 0.01 to 10 탆, and preferably 0.1 to 5 탆. When the thickness of the adhesive layer is 0.5 탆 or less, there is a high possibility that air bubbles are mixed at the time of bonding, and when the thickness of the adhesive layer is 5 탆 or more, the price increases.

In order to improve the adhesion, the surface of the polarizer and / or the protective film may be suitably subjected to a surface treatment such as a chemical treatment such as a primer treatment, a plasma treatment, a corona treatment, or a dry treatment or a saponification (alkali) treatment . Examples of the saponification (alkali) treatment include a method of immersing in an aqueous solution of an alkali such as sodium hydroxide or potassium hydroxide.

The other side of the polarizer to which the protective film is bonded on one side may be suitably subjected to surface treatment such as hard coat treatment, antireflection treatment, anti-stick treatment, diffusion or anti-glare treatment as required.

In addition to the above-described surface treatment, the other surface of the polarizer to which the protective film is bonded on one surface may further be laminated with a surface treatment layer such as a hard coating layer, an antireflection layer, an antiglare layer and an antistatic layer, An optical functional film may be further laminated.

The type of the optically functional film is not particularly limited. For example, an optically compensatory film in which a liquid crystalline compound or a polymer compound thereof is oriented on the surface of a base material, an optically compensatory film which transmits polarized light of any kind, A retardation film including a polycarbonate resin, a retardation film including a cyclic polyolefin resin, an anti-glare function film having a concavo-convex shape on its surface, an additional film having a surface antireflection treatment, A transflective film having both a reflective function and a transmissive function, and the like.

Such a polarizing plate can be applied to all normal image devices.

The polarizer plate bonded with the adhesive composition of the present invention is excellent in adhesion between the polarizer and the protective film and water resistance without curing for a long time after the bonding.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to be illustrative of the invention and are not intended to limit the scope of the claims. It will be apparent to those skilled in the art that such variations and modifications are within the scope of the appended claims.

Example  And Comparative Example

A polyvinyl alcohol film having a thickness of 75 탆 and an average degree of polymerization of 2,400 and a saponification degree of 99.9 mol% or more was uniaxially stretched by a dry method about 5 times and immersed in water (distilled water) at 60 캜 for 1 minute while maintaining the stretched state And immersed for 60 seconds in an aqueous solution at 28 DEG C in which the weight ratio of after-iodine / potassium iodide / distilled water was 0.05 / 5/100. Subsequently, the substrate was immersed in an aqueous 72 ° C aqueous solution having 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 give a polyvinyl alcohol film Polarized polarizers were prepared.

On both sides of the polarizer, an adhesive composition having the composition and content shown in Table 1 below was applied to a thickness of 2 占 퐉, and then a triacetyl cellulose-based protective film corona-treated with niprol and a norbornene- After the olefin polymer protective film was bonded, the polarizing plate was cured by irradiating UV with a high-pressure mercury lamp (UVA cumulative light quantity: 500 mJ / cm ² , illuminance: 500 mW / cm ² ).

division Photopolymerizable compound Cross-linking agent
(C) Radical
Photoinitiator
(D) In formulas (1) and (2)
compound
(A) Acrylic compound
(B) ingredient Weight portion ingredient Weight portion Weight portion Weight portion Example 1 A-1 One B-1
/ B-2 43/50 One 5 Example 2 A-1 3 B-1
/ B-2 41/50 One 5 Example 3 A-1 5 B-1
/ B-2 39/50 One 5 Example 4 A-1 7 B-1
/ B-2 37/50 One 5 Example 5 A-1 10 B-1
/ B-2 34/50 One 5 Example 6 A-2 7 B-1
/ B-2 37/50 One 5 Example 7 A-3 7 B-1
/ B-2 37/50 One 5 Example 8 A-4 7 B-1
/ B-2 37/50 One 5 Example 9 A-5 7 B-1
/ B-2 37/50 One 5 Example 10 A-6 7 B-1
/ B-2 37/50 One 5 Example 11 A-7 7 B-1
/ B-2 37/50 One 5 Example 12 A-1 7 B-1
/ B-3 37/50 One 5 Example 13 A-1 7 B-3
/ B-4 37/50 One 5 Example 14 A-1 7 B-3
/ B-5 37/50 One 5 Example 15 A-1 9 B-1 86 - 5 Example 16 A-2 9 B-1 86 - 5 Example 17 A-1 0.5 B-1 93.5 One 5 Example 18 A-1 15 B-1 79 One 5 Example 19 A-1 20 B-1 74 One 5 Example 20 A-1 22 B-1 72 One 5 Comparative Example 1 - - B-2 95 - 5 Comparative Example 2 - - B-2 /
B-5 50/45 - 5 Comparative Example 3 - - B-2 /
B-5 50/44 One 5 Comparative Example 4 - - B-3 /
B-5 50/45 - 5 Comparative Example 5 - - B-5 95 - 5 Comparative Example 6 - - B-3 95 - 5 Comparative Example 7 - - B-2 94 One 5 Comparative Example 8 - - B-3 /
B-5 50/44 One 5 Comparative Example 9 - - B-1 /
B-2 /
B-6 37/50/7 One 5 A-1: beta-mercaptopropionic acid
A-2: methyl-3-mercaptopropionate
A-3: 2-Ethylhexyl-3-mercaptopropionate
A-4: n-octyl-3-mercaptopropionate
A-5: Methoxybutyl-3-mercaptopropionate
A-6: Stearyl-3-mercaptopropionate
A-7: Trimethylolpropane tris (3-mercaptopropionate)
B-1: 2-hydroxybutyl acrylate
B-2: 4-hydroxybutyl acrylate
B-3: N-Hydroxyethylacrylamide
B-4: N-methyl acrylamide
B-5: N-acryloylmorpholine
B-6: Mercaptomethyl (meth) acrylamide
C: A-TMM (Kowa Co.)
D: darocur TPO (Shiba)

Experimental Example

(1) Evaluation of initial adhesion force development time

The polarizers produced in Examples and Comparative Examples were evaluated for adhesion at intervals of 5 minutes according to the method of Experimental Example (2) described below, and the time when the cutter blade fell below 2 mm between the polarizer and the protective film was evaluated as initial The adhesive force was measured by the expression time.

(2) Evaluation of adhesion

The polarizers prepared in Examples and Comparative Examples were allowed to stand at 23 DEG C and 55% relative humidity for 24 hours, and then the adhesiveness between the polarizer and the protective film to such an extent that the blades were inserted into the gap between the polarizer and the protective film Respectively.

◎: The cutter blade does not enter between the polarizer and the protective film.

○: The cutter blade enters 2 mm or less between the polarizer and the protective film

DELTA: The blade of the cutter enters between 2 mm and 5 mm or less between the polarizer and at least one protective film

X: The blade of the cutter enters the gap between the polarizer and at least one protective film without any difficulty

(3) Water temperature  evaluation

After leaving the polarizing plate prepared in the above Examples and Comparative Examples at 23 占 폚 and 55% relative humidity for 24 hours, a sample of 5 cm 占 2 cm was prepared with the absorption axis (stretching direction) as long sides. Then, the short sides of each sample were gripped, and 80% of the longitudinal direction was immersed in a water bath of 60 ° C for 4 hours, and then taken out to wipe out the water.

Since the polarizer shrinks due to immersion in hot water, the distance from the end of the protective film at the center of the short side of the sample to the shrunk polarizer was measured and made to be the shrink length.

In addition, since iodine eluted from the periphery of the polarizer due to hot water immersion and discolored, the distance from the end of the shrunk polarizer at the center of the short side of the sample to the uncolored portion was defined as the iodine dropout length.

The sum of the shrinkage length and the iodine dropout length was taken as the total erosion length. That is, the total erosion length is the distance from the end of the protective film at the center of the short side of the sample to the non-decolorized portion of the polarizer. The smaller the erosion length is, the better the water resistance is.

◎: total erosion length less than 2mm

○: total erosion length is 2 mm or more to less than 3 mm

△: total erosion length is 3 mm or more and less than 5 mm

X: Total erosion length is 5mm or more

division Initial adhesion
Expression time (min) Adhesiveness Water temperature Example 1 120 ◎ ◎ Example 2 80 ◎ ◎ Example 3 35 ◎ ◎ Example 4 25 ◎ ◎ Example 5 10 ◎ ◎ Example 6 25 ◎ ◎ Example 7 25 ◎ ◎ Example 8 25 ◎ ◎ Example 9 25 ◎ ○ Example 10 25 ◎ ○ Example 11 5 ◎ ◎ Example 12 40 ◎ ◎ Example 13 55 ◎ ◎ Example 14 110 ○ ◎ Example 15 80 ○ ◎ Example 16 70 ○ ◎ Example 17 360 ○ ◎ Example 18 70 ○ ◎ Example 19 150 ○ ◎ Example 20 440 ○ ○ Comparative Example 1 1,200 ○ X Comparative Example 2 900 ○ X Comparative Example 3 700 ○ △ Comparative Example 4 900 ○ X Comparative Example 5 1,000 ○ X Comparative Example 6 600 ○ X Comparative Example 7 600 ○ △ Comparative Example 8 700 ○ △ Comparative Example 9 600 △ X

Referring to Table 1, the adhesive compositions of Examples 1 to 20 exhibited excellent adhesion without performing a curing process for a long period of time because the initial adhesion force was shortened. Also, it was excellent in adhesiveness and water resistance.

The adhesive compositions of Comparative Examples 1 to 9 took 10 hours or more in order to exhibit sufficient adhesive strength, and the resistance to water resistance was remarkably decreased.

Claims (7)

A photopolymerizable compound and a radical photoinitiator,
Wherein the photopolymerizable compound comprises at least one compound of the following general formulas (1) and (2) and an acrylic compound:
[Chemical Formula 1]

(Wherein R represents a hydrogen atom, a linear or branched alkyl group having 1 to 20 carbon atoms which is substituted or unsubstituted with an alkoxy group having 1 to 5 carbon atoms, an isocyanurate group,

,

, or

ego,
m is an integer from 1 to 8;
R ₁ is an alkylene group having 1 to 5 carbon atoms;
n is an integer of 1 to 4)
(2)

(Wherein R is a straight or branched alkyl group having 1 to 20 carbon atoms which is substituted or unsubstituted with a hydrogen atom or an alkoxy group having 1 to 5 carbon atoms;
R ₁ is an alkylene group having 1 to 5 carbon atoms;
and n is an integer of 1 to 4).
[2] The composition of claim 1, wherein the compound of Formulas 1 and 2 is selected from the group consisting of beta-mercaptopropionic acid, methyl-3-mercaptopropionate, 2-ethylhexyl-3-mercaptopropionate, Mercaptopropionate, stearyl-3-mercaptopropionate, trimethylolpropane tris (3-mercaptopropionate), tris [3-mercaptopropionyloxy -Ethyl] isocyanurate, pentaerythritol tetrakis (3-mercaptopropionate) and tetraethylene glycol bis (3-mercaptopropionate).
The adhesive composition for a polarizing plate according to claim 1, wherein the compounds of the formulas (1) and (2) are contained in an amount of 1 to 20% by weight based on the total weight of the composition.
[2] The method of claim 1, wherein the acrylic compound is at least one selected from the group consisting of N-methyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N- (Meth) acrylamide, N-methylol (meth) acrylamide, N-methylol (meth) acrylamide, 3-phenoxypropyl (meth) acrylate, aminomethyl (meth) acrylamide, aminoethyl (meth) acrylamide, mercaptomethyl (Meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, and 2-hydroxypropyl , 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) (Meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, At least one selected from the group consisting of hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate and 8-hydroxyoctyl (meth) acrylate.
The adhesive composition for a polarizing plate according to claim 1, wherein the radical photoinitiator is at least one selected from the group consisting of a carbonyl photoinitiator, a benzoin ether photoinitiator, and an acetophenone photoinitiator.
The adhesive composition for a polarizing plate according to claim 1, further comprising a crosslinking agent.
Wherein a protective film is bonded to at least one surface of the polarizer with the adhesive composition for a polarizing plate according to any one of claims 1 to 6.