KR20200067669A - Adhesive film for polarizing plate, polarizing plate comprising the same and optical display apparatus comprising the same - Google Patents

Abstract

Provided are an adhesive film for a polarizing plate formed of an adhesive composition for a polarizing plate, including a (meth) acrylic copolymer, an isocyanate-based crosslinking agent, a metal chelate-based crosslinking agent, a silane coupling agent oligomer, a silane coupling agent monomer, and an interface modifier, and a polarizing plate and an optical display device including the same.

Description

Adhesive film for polarizing plate, polarizing plate comprising the same, and optical display device including the same {ADHESIVE FILM FOR POLARIZING PLATE, POLARIZING PLATE COMPRISING THE SAME AND OPTICAL DISPLAY APPARATUS COMPRISING THE SAME}

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

The liquid crystal display device is composed of a liquid crystal cell and a polarizing plate attached to both sides of the liquid crystal cell. The polarizing plate is composed of a protective film for protecting both sides of a polyvinyl alcohol (PVA) film and a PVA film, and is attached to a liquid crystal cell using an adhesive. Each of the films constituting the polarizing plate is formed in a structure in which films made of different molecular structures are stacked, and if exposed to harsh environments such as high temperature and high humidity, the film is denatured. At this time, stress occurs in the pressure-sensitive adhesive due to shrinkage or expansion of the film, and if the pressure-sensitive adhesive does not have durability such as heat resistance and moisture heat resistance, excitation occurs in which the film is peeled from the liquid crystal cell under conditions of high temperature and high humidity, or air bubbles are generated. Easy to appear Therefore, the pressure-sensitive adhesive for bonding the liquid crystal cell and the polarizing plate must satisfy physical properties such as adhesion to the object, heat resistance, and moisture heat resistance.

When the polarizing plate is fixed by the adhesive, when the polarizing plate shrinks or expands under high temperature/high humidity conditions, stress is concentrated in the protective film layer, birefringence occurs, and thus light leakage is likely to occur. This is called a light leakage phenomenon and is generally known to occur due to the optical isotropy of a stretched polarizing film shrinking in an environment of high temperature and high humidity and having non-isotropy.

Therefore, in order to prevent light leakage, techniques have been carried out to control the shrinkage of the polarizing plate generated under high temperature/high humidity conditions by increasing the molecular weight of the acrylate binder constituting the adhesive or increasing the modulus according to the increase in crosslinking density. However, the general design for preventing light leakage must inevitably lead to a decrease in durability. It is especially vulnerable to long-term durability.

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

An object of the present invention is to provide a pressure-sensitive adhesive film for a polarizing plate excellent in long-term durability reliability because the adhesive strength is maintained or the adhesive strength is increased compared to the initial state even after leaving for a long time as a hard-type polarizing adhesive film.

Another object of the present invention is to provide an adhesive film for a polarizing plate having excellent durability reliability in an initial state and high durability reliability even after being left for a long period of time.

Another object of the present invention is to provide an adhesive film for a polarizing plate having excellent reworkability and cutability.

Another object of the present invention is to provide a pressure-sensitive adhesive film for a polarizing plate that can excellently prevent light leakage that occurs when stress is concentrated in the protective film and birefringence occurs when the polarizing plate contracts or expands under high temperature/high humidity conditions.

1. The adhesive film for polarizing plates of the present invention is formed of an adhesive composition for a polarizing plate comprising a (meth)acrylic copolymer, an isocyanate-based crosslinking agent, a metal chelate-based crosslinking agent, a silane coupling agent oligomer, a silane coupling agent monomer, and an interface modifier.

2. In 1, the adhesive film for the polarizing plate may have a difference in adhesive strength according to Equation 1 below from 0 gf/25 mm to 50 gf/25 mm:

[Equation 1]

Difference in adhesion = AS2-AS1

(In Formula 1, AS1 is the adhesive strength of the adhesive film for polarizing plates to the glass plate at 25°C (unit: gf/25mm)

AS2 is the adhesive film for the polarizing plate at 25° C. and relative humidity of 55% for 180 days, and then at 25° C., the adhesive strength of the adhesive film for the polarizing plate to the glass plate (unit: gf/25 mm).

3. In 1-2, the adhesive film for the polarizing plate may have a modulus of 0.8 MPa or higher at 25°C.

4. In 1-3, the adhesive film for the polarizing plate may have a modulus of 0.3 MPa or more at 85°C.

5. In 1-4, the adhesive film for the polarizing plate may have a modulus difference according to the following Equation 2 of 1.0 MPa or less:

[Equation 2]

Modulus difference = G'(25℃)-G'(85℃)

(In the formula 2, G'(25 °C) is storage modulus at 25 °C of the adhesive film for polarizing plates (unit: MPa),

G'(85°C) is the storage modulus at 85°C of the adhesive film for polarizing plates (unit: MPa).

6. In 1-5, in the adhesive film for the polarizing plate, AS1 and AS2 in Equation 1 may be 200 gf/25 mm or more, respectively.

7. In 1-6, the weight ratio of the isocyanate-based cross-linking agent: the metal chelate-based cross-linking agent may be included as 50:1 to 100:1.

8. In 1-7, the silane coupling agent monomer may include a silane coupling agent monomer having an epoxy structure.

9. In 1-8, the silane coupling agent oligomer may include an epoxy-based silane coupling agent oligomer.

10. In 1-9, the interface modifier may include an epoxy-based modified silicone oil.

11. In 1-10, the pressure-sensitive adhesive composition for a polarizing plate is

100 parts by weight of the (meth) acrylic copolymer

10 to 30 parts by weight of the total amount of the isocyanate-based crosslinking agent and the metal chelate-based crosslinking agent,

The silane coupling agent oligomer 0.001 parts by weight to 5.0 parts by weight

0.001 part by weight to 1 part by weight of the silane coupling agent monomer, and

It may include 0.001 parts by weight to 1.0 parts by weight of the interface modifier.

12. In 1-11, the polarizing plate adhesive film may have a surface energy of 40 mJ/m ² or less measured at 25° C. after 180 days at 25° C. and 55% relative humidity.

13. In 1-12, the (meth)acrylic copolymer is a copolymer of a monomer mixture comprising a (meth)acrylic monomer having an alkyl group, a (meth)acrylic monomer having a hydroxyl group, and a (meth)acrylic monomer having a carboxylic acid group. It can contain.

14. In 1-13, the monomer mixture is 90% to 99% by weight of the (meth)acrylic monomer having the alkyl group, 0.01% to 5% by weight of the (meth)acrylic monomer having the hydroxyl group and the carboxylic acid group ( It may contain from 0.01% to 5% by weight of a meth)acrylic monomer.

15. In 1-14, the adhesive film for the polarizing plate may further include a rework agent.

16. In 1-15, the rework agent may include a polyether-modified silicone oil.

The polarizing plate of this invention contains the adhesive film for polarizing plates of this invention.

The optical display device of the present invention includes the polarizing plate of the present invention.

The present invention provides a pressure-sensitive adhesive film for a polarizing plate having excellent long-term durability reliability because the adhesive strength is maintained or the adhesive strength is increased compared to the initial state even after leaving for a long time as a hard-type polarizing adhesive film.

The present invention provides an adhesive film for a polarizing plate having excellent durability reliability and high durability reliability even after being left for a long time.

The present invention provides an adhesive film for a polarizing plate excellent in rework property and cutting property.

The present invention provides a pressure-sensitive adhesive film for a polarizing plate that can excellently prevent light leakage caused by stress concentration and birefringence when the polarizing plate contracts or expands under high temperature/high humidity conditions.

1 is a conceptual view showing a plane of a specimen for measuring light leakage.

The present invention will be described in detail with reference to the following examples so that those skilled in the art to which the present invention pertains can easily practice. The present invention can be implemented in many different forms and is not limited to the embodiments described herein.

In the present specification, “adhesive film for polarizing plate” and “adhesive composition for polarizing plate” may be referred to as “adhesive film” and “adhesive composition”, respectively.

As used herein, "(meth)acrylic" means acrylic and/or methacryl.

In this specification, the adhesive force "AS1" of the adhesive film for polarizing plates is the adhesive force between the adhesive film for polarizing plates and a glass plate. The adhesive force is a value evaluated according to JIS 2107 standard.

Specifically, "AS1" is a pressure-sensitive adhesive film for a polarizing plate and a glass plate in a 30kgf load cell in a tensile test measuring machine (Texture Analyzer) after laminating a pressure-sensitive adhesive film for a polarizing plate onto a glass plate and cutting it into a rectangular specimen having a width x length (25mm x 100mm). It is a value measured by connecting the upper and lower jigs, respectively, and measuring the load at the time of peeling of the adhesive film for polarizing plates from the glass plate at a measurement temperature of 25°C, a peeling angle of 180°, and a tensile speed of 300 mm/min.

In the present specification, the adhesive force “AS2” of the adhesive film for polarizing plates was released for 180 days at 25° C. and relative humidity of 55% with a release film (polyethylene terephthalate film) attached to the adhesive film for polarizing plates, and then the release film was peeled off. , The adhesive force was measured in the same manner as in AS1.

In this specification, "the glass transition temperature of the homopolymer" may mean the glass transition temperature (Tg) measured by using DSC Discovery of TA Instrument for the homopolymer of the monomer to be measured. Specifically, the temperature of the homopolymer of the monomer to be measured is increased from 25°C to 180°C at a rate of 20°C/min, cooled gradually to -100°C, and then raised to 100°C at a rate of 10°C/min. After obtaining the data of the endothermic transition curve, the inflection point of the endothermic transition curve can be determined as the glass transition temperature.

When describing a numerical range in this specification, “X to Y” means “X= and ≤Y” (X or more and Y or less).

The inventor of the present invention has solved the problem of durability reliability due to deterioration of adhesive strength over time in the hard type adhesive film for polarizing plates. Specifically, the inventors of the present invention compared the initial adhesive strength of the adhesive film for polarizing plates to the adhesive strength after leaving the adhesive film for polarizing plates at 25° C. and relative humidity for 55 days for 180 days (hereinafter, also referred to as “aging adhesive force”). The adhesive strength with time was excellent by keeping it in an equal state or by raising it higher. To this end, the inventors of the present invention formed a pressure-sensitive adhesive film for a polarizing plate with an adhesive composition comprising a (meth)acrylic copolymer, an isocyanate-based crosslinking agent, a metal chelate-based crosslinking agent, a silane coupling agent oligomer, a silane coupling agent monomer, and an interface modifier. In general, a hard type adhesive film for a polarizing plate has a high modulus at high temperature, so that light leakage can be suppressed by controlling the stress of the polarizing plate at high temperature, but a high modulus has low adhesion to an adherend, for example, a glass plate. Particularly, when the adhesive film for a hard type polarizing plate is left for 6 months or longer at room temperature, the adhesive strength to the adherend becomes lower due to a high modulus, resulting in poor durability. The present inventor solved the above-mentioned problem of the hard type adhesive film for a polarizing plate.

Hereinafter, an adhesive film for a polarizing plate according to an embodiment of the present invention will be described.

The adhesive film for polarizing plates of this invention is a hard type adhesive film for polarizing plates. It is known to those skilled in the art that the polarizing plate adhesive film is divided into a hard type polarizing plate adhesive film and a soft type polarizing plate adhesive film, which are classified according to storage modulus.

The adhesive film for polarizing plates is a hard type adhesive film for polarizing plates and may have a modulus of 0.8 MPa or more, for example, 0.8 MPa to 2.0 MPa, 0.8 MPa to 1.0 MPa, at 25°C. In the above range, the adhesive film for a polarizing plate has a high modulus even at a high temperature, so that light leakage can be excellently prevented.

In one embodiment, the adhesive film for a polarizing plate may have a modulus of 0.3 MPa or more, for example, 0.3 MPa to 2.0 MPa, 0.3 MPa to 1.0 MPa at 85°C. In the above range, the adhesive film for a polarizing plate can excellently prevent light leakage at high temperature.

In one embodiment, the adhesive film for a polarizing plate may have a modulus difference according to the following Equation 2 of 1.0 MPa or less, for example, 0 MPa to 1.0 MPa, 0 MPa to 0.7 MPa:

[Equation 2]

Modulus difference = G'(25℃)-G'(85℃)

(In the formula 2, G'(25 °C) is storage modulus at 25 °C of the adhesive film for polarizing plates (unit: MPa),

G'(85°C) is the storage modulus at 85°C of the adhesive film for polarizing plates (unit: MPa).

The adhesive film for a polarizing plate may have a difference in adhesive strength according to Equation 1 below from 0 gf/25 mm to 50 gf/25 mm: In the above range, the adhesive strength for polarizing plates is maintained or increased over time compared to the initial adhesive strength of the adhesive film for polarizing plates, and the adhesive film for polarizing plates is left for a long time. Even after doing so, the durability can be excellent by securing the adhesive strength: Preferably, the difference in adhesive strength according to Equation 1 may be 0 gf/25 mm to 30 gf/25 mm:

[Equation 1]

Difference in adhesion = AS2-AS1

(In the formula 1, AS1 is the adhesive force of the adhesive film for the polarizing plate to the glass plate (unit: gf / 25mm),

AS2 is the adhesive force for the polarizing plate to the glass plate after leaving the adhesive film for 25 days at 25 °C and relative humidity of 55% for 180 days (unit: gf / 25mm)).

In one embodiment, in the adhesive film for a polarizing plate, AS1 in Formula 1 may be 200 gf/25 mm or more, for example, 200 gf/25 mm to 500 gf/25 mm. In the adhesive film for a polarizing plate, AS2 in Formula 1 may be 200 gf/25 mm or more, for example, 200 gf/25 mm to 550 gf/25 mm. In the above range, the adhesive strength difference of the present invention can be easily secured, and the durability reliability of the adhesive film for a polarizing plate may be excellent, and there may be no problem in rework after lamination on a glass plate.

On the other hand, the pressure-sensitive adhesive film for a polarizing plate can be easily peeled off the release film for the polarizing plate by significantly lowering the peel force for the release film compared to the above-described AS1, AS2. The initial peel force for the release film of the adhesive film for polarizing plates may be 5 gf/25 mm or less, for example, 1 gf/25 mm to 3 gf/25 mm, 1.2 gf/25 mm to 2.2 gf/25 mm.

After the adhesive film for polarizing plates is adhered to a release film, after 180 days at 25°C and a relative humidity of 55%, the peeling force of the adhesive film for polarizing plates to a release film is 5 gf/25 mm or less, for example, 3 gf/25 mm to 5 gf /25mm, 3gf/25mm to 4.5gf/25mm.

The "release film" may be a polyethylene terephthalate film or the like, and the polyethylene terephthalate film may or may not be pre-treated with corona on one surface (the surface laminated with the adhesive film for polarizing plates).

The adhesive film for polarizing plates may be formed of an adhesive composition comprising a (meth)acrylic copolymer, an isocyanate-based crosslinking agent, a metal chelate-based crosslinking agent, a silane coupling agent oligomer, a silane coupling agent monomer, and an interface modifier.

The pressure-sensitive adhesive composition contains a mixture of an isocyanate-based crosslinking agent and a metal chelate-based crosslinking agent as a crosslinking agent. By crosslinking the (meth)acrylic-type copolymer described below, the isocyanate-based crosslinking agent can increase the modulus of the adhesive film for polarizing plates to implement a hard type adhesive film for polarizing plates. The metal chelating agent crosslinking agent increases the modulus of the adhesive film for polarizing plates by crosslinking the (meth)acrylic-based copolymer described below to implement a hard type adhesive film for a polarizing plate, and silanes through a change in the structure of the adhesive layer such as air bubbles in the adhesive layer Coupling agent oligomer and silane coupling agent may help to increase the adhesive strength over time due to the monomer.

The total amount of the isocyanate-based crosslinking agent and the metal chelate-based crosslinking agent may be included in 10 parts by weight to 30 parts by weight, for example, 10 parts by weight to 20 parts by weight, and 10 parts by weight to 15 parts by weight based on 100 parts by weight of the (meth)acrylic copolymer. have. In the above range, light leakage may be excellently prevented under high temperature/high humidity, and long-term reliability may be excellent.

The isocyanate-based crosslinking agent: The weight ratio of the metal chelate-based crosslinking agent may be included as 50:1 to 100:1, for example, 60:1 to 80:1. In the above range, light leakage may be excellently prevented under high temperature/high humidity, and long-term reliability may be excellent.

In the pressure-sensitive adhesive composition of the present invention, when the epoxy-based crosslinking agent was included instead of the metal chelate-based crosslinking agent, the adhesive strength was not improved over time, and the long-term reliability and cutability of the pressure-sensitive adhesive layer were also poor. In the pressure-sensitive adhesive composition of the present invention, when the aziridine-based crosslinking agent was included instead of the metal chelate-based crosslinking agent, there was no effect of improving adhesion over time, and long-term reliability of the pressure-sensitive adhesive layer was also poor. In the case of including the amine-based curing agent in the pressure-sensitive adhesive composition of the present invention instead of a metal chelate-based crosslinking agent, there is a problem of reducing pot-life such as an increase in viscosity over time after mixing of the pressure-sensitive adhesive.

The isocyanate-based crosslinking agent may include an isocyanate-based crosslinking agent having two or more functionalities, for example, trifunctional to hexafunctional. For example, the isocyanate-based crosslinking agent is methylene bis(phenylisocyanate) (MDI), naphthalene, including xylene diisocyanate (XDI) including m-xylene diisocyanate, and 4,4'-methylenebis (phenylisocyanate). Diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, one or more of isophorone diisocyanate, or adducts thereof, or isocyanurates thereof. For example, as the adduct or isocyanurate, trimethylolpropane adduct of tolylene diisocyanate, trimethylolpropane adduct of hexamethylene diisocyanate, trimethylolpropane adduct of isophorone diisocyanate, xylene diisocyanate It may be a trimethylolpropane adduct, an isocyanurate form of tolylene diisocyanate, an isocyanurate form of hexamethylene diisocyanate, an isocyanurate form of isophorone diisocyanate. For example, as the tolylene diisocyanate system, it may be tolylene diisocyanate, trimethylolpropane adduct of tolylene diisocyanate, or trifunctional adduct of tolylene diisocyanate.

The isocyanate crosslinking agent may be included in 5 parts to 25 parts by weight, preferably 10 parts to 20 parts by weight, and 13 parts to 16 parts by weight based on 100 parts by weight of the (meth)acrylic copolymer. In the above range, the adhesive strength with time rises, reworkability and cutability are good, and long-term reliability may be good.

The metal chelating crosslinking agent may include a metal chelating crosslinking agent commonly used by those skilled in the art as a crosslinking agent composed of a metal and a chelate bond. In one embodiment, the metal chelate-based crosslinking agent may include a crosslinking agent having two or more metal and chelating bonds, for example, three to six. For example, the metal may include aluminum, zirconium, titanium, and cobalt, preferably aluminum. For example, the chelate may include, but is not limited to, acetylacetonate, ethylacetoacetate, and the like. Specifically, the metal chelate-based crosslinking agent is acetylacetonate aluminate, aluminum tris (acetylacetonate), aluminum tris (ethyl acetoacetate), aluminum bis (acetoacetate), zirconium tris (acetylacetonate), cobalt tris (acetylaceto Nate), but is not limited thereto.

The metal chelating crosslinking agent is 0.05 parts by weight to 1.0 parts by weight, preferably 0.1 parts by weight to 0.5 parts by weight, 0.15 parts by weight to 0.25 parts by weight, and 0.19 parts by weight to 0.23 parts by weight based on 100 parts by weight of the (meth)acrylic copolymer. Can be included. In the above range, there is little change in adhesive strength over time in a high-humidity environment, and long-term reliability may be good.

The silane coupling agent monomer may combine an adhesive film for a polarizing plate and a glass plate to increase the initial adhesive strength of the adhesive film for a polarizing plate and increase the initial durability reliability. The silane coupling agent monomer has an alkoxysilane group and is a repeating unit of "*-Si-O-* (* is a linking site, two substituents bonded to Si are not shown)" resulting from the hydrolysis condensation reaction between alkoxysilane groups. And non-hydrolyzate. The silane coupling agent monomer has a lower weight average molecular weight than the silane coupling agent oligomer described below. For example, the silane coupling agent monomer may have a weight average molecular weight of 350 or less, for example, 0 to 300.

The silane coupling agent monomer may include conventional silane coupling agent monomers known to those skilled in the art. Specifically, the silane coupling agent monomer has an epoxy structure such as 3-glycidoxypropyl trimethoxysilane, 3-glycidoxypropyl methyl dimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl trimethoxysilane, and the like. A silicon compound having; Polymerizable unsaturated group-containing silicon compounds such as vinyl trimethoxysilane, vinyl triethoxysilane and (meth)acryloxypropyl trimethoxysilane; Amino group-containing silicon compounds such as 3-aminopropyl trimethoxysilane, N-(2-aminoethyl)-3-aminopropyl trimethoxysilane, and N-(2-aminoethyl)-3-aminopropyl methyl dimethoxysilane ; And 3-chloro propyl trimethoxysilane and the like, but is not limited to these. Preferably, the silane coupling agent monomer may include a silane coupling agent monomer having an epoxy structure.

The silane coupling agent monomer may be included in an amount of 0.001 part by weight to 1 part by weight, specifically 0.01 part by weight to 0.5 part by weight based on 100 parts by weight of the (meth)acrylic copolymer. In the above range, the initial adhesive strength of the pressure-sensitive adhesive film for a polarizing plate may be high and durability reliability may be excellent.

The silane coupling agent oligomer can maintain the adhesive strength or increase the adhesive strength compared to the initial adhesive strength after leaving for a long time compared to the initial adhesive strength of the adhesive film for polarizing plates even if the adhesive film for polarizing plates is left for a long time, or rather increase the adhesive strength, and the adhesive for polarizing plates It is possible to increase the durability of the film over time. As described above, the adhesive film for a polarizing plate having a modulus of 0.8 MPa or higher at 25° C., although the initial adhesive strength can be increased by a silane coupling agent monomer, the adhesive strength is inevitably lowered due to an increase in the modulus of the adhesive film when left for a long time. On the other hand, the silane coupling agent oligomer can maintain the initial adhesive strength or increase the adhesive strength even after leaving the adhesive film for polarizing plates for a long time. The action of the silane coupling agent oligomer can be derived from the action of the interface modifier described below. This will be described in detail below.

If the silane coupling agent oligomer is not used and instead contains an excess amount of the silane coupling agent monomer, there may be a problem in rework after laminating the panels with a glass peel force of 2000 gf/25 mm or more. In addition, when the silane coupling agent oligomer is not used and instead a tackifier is included, there is only an effect of increasing the initial glass peel strength, and there is no effect of maintaining or increasing the adhesive strength with the glass after leaving for a long time, so there is no increase in reliability and wrinkles There is a problem due to occurrence. As described above, in the present invention, the silane coupling agent monomer and the silane coupling agent oligomer may be used in combination with the above-mentioned two types of crosslinking agent and an interface modifier to simultaneously secure initial adhesion and aging adhesion of the polarizing plate adhesive film.

The silane coupling agent oligomer has an alkoxysilane group and repeats "*-Si-O-* (* is a linking site, two substituents bonded to Si are not indicated)" resulting from the hydrolysis condensation reaction between the alkoxysilane groups. Hydrolysis condensation reaction products having units. For example, the silane coupling agent oligomer may include a material prepared by hydrolysis condensation reaction of a specific type of the silane coupling agent monomer described above. Among them, an epoxy-based silane coupling agent oligomer containing a hydrolysis-condensation product of a silicon compound having an epoxy structure can be used as a hydrolysis-condensation product of a particularly preferred silane coupling agent monomer.

The silane coupling agent oligomer may have a weight average molecular weight of 1000 or more. In the above range, compatibility with the adhesive binder is excellent and may have an effect of maintaining or increasing the glass adhesive strength even when left at room temperature for a long time. Preferably, the weight average molecular weight may be 1000 to 3000. In the above range, the compatibility with the adhesive binder is excellent and the coating liquid of the adhesive composition does not turn bluish, so the coating appearance may have a uniform effect.

The silane coupling agent oligomer may be included in an amount of 0.001 parts by weight to 5.0 parts by weight, for example, 0.01 parts by weight to 1.0 parts by weight, and 0.01 parts by weight to 0.5 parts by weight based on 100 parts by weight of the (meth)acrylic copolymer. In the above range, even after a long period of standing (6 months), the glass adhesive strength may have an effect of excellent durability reliability according to maintenance or increase of the initial contrast.

The content of the silane coupling agent oligomer is preferably determined in consideration of the content of the silane coupling agent monomer. Only then, while securing the rework property of the adhesive film for a polarizing plate, it is possible to simultaneously increase the initial adhesive strength and aging adhesive strength described above.

In one embodiment, it is preferred that the silane coupling agent oligomer is included in an excess amount compared to the silane coupling agent monomer. Silane coupling agent oligomer: The weight ratio of the silane coupling agent monomer may be 1.5:1 to 5:1, for example, 2:1 to 5:1. In the above range, the adhesive strength with time of the polarizing plate adhesive film is secured and may have an effect of preventing the rework property from deteriorating.

The interface modifier allows the surface of the polarizing plate adhesive film and the glass plate surface to be compatible with each other and improves wettability, so that the silane coupling agent monomer and the silane coupling agent oligomer are present on the adhesive film surface, thereby increasing the adhesive strength over time. Can be.

In one embodiment, a surface adjusting agent is a surface energy measured at 25 ℃ after 180 days have passed from the pressure-sensitive adhesive film is 25 ℃ and a relative humidity of 55% for a polarizing plate 40mJ / m ² or less, for example, 30mJ / m ² to 40mJ / m It can be set to ² . In the above range, even after leaving for a long period of time, the wettability of the adhesive film for a polarizing plate is improved, which may help increase the adhesive strength over time. The surface energy can be measured using the Phoenix50 contact angle measuring device using the Sessile Drop Contact Angle Method, but is not limited thereto.

The interface modifier may have a weight average molecular weight of 100 to 500, for example, 180 to 380, 230 to 330. In the above range, it may be effective in improving the wetting property as it is effectively present at the interface with the glass plate. The surfactant may be modified silicone oil, for example, epoxy-based modified silicone oil.

In one embodiment, the interface modifier may include a silicone oil represented by Formula 1 below:

<Formula 1>

(In <Formula 1> above,

R ¹ to R ¹⁰ are each independently hydrogen, an unsubstituted alkyl group having 1 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms substituted with an epoxy group or an epoxy group, and at least one of R ¹ to R ¹⁰ is an epoxy group or an epoxy group A substituted C 1 to C 10 alkyl group,

n is an integer from 0 to 1, m is an integer from 1 to 10, n+m is not 0)

Preferably, the interface modifier may include a silicone oil represented by Formula 2 below:

<Formula 2>

(In <Formula 2>,

R ⁷ is an epoxy group or an alkyl group having 1 to 10 carbon atoms substituted with an epoxy group, n is an integer from 0 to 1, and m is an integer from 1 to 10).

The interface modifier may be CK-843A (NCI), but is not limited thereto.

The interface modifier may be included in an amount of 0.001 part by weight to 1.0 part by weight, for example, 0.01 part by weight to 1 part by weight, and 0.01 part by weight to 0.1 part by weight based on 100 parts by weight of the (meth)acrylic acid copolymer. In the above range, it is possible to improve the adhesion between the adhesive film for a polarizing plate and a glass plate, improve durability, and have a release film peeling force of 5 gf/25 mm or less depending on long-term standing.

The (meth)acrylic copolymer increases the modulus of the adhesive film by forming a matrix of the adhesive film for polarizing plates and curing with a crosslinking agent. The (meth)acrylic copolymer includes a copolymer of a monomer mixture comprising a (meth)acrylic monomer having an alkyl group, a (meth)acrylic monomer having a hydroxyl group, and a (meth)acrylic monomer having a carboxylic acid group.

The (meth)acrylic monomer having an alkyl group may include (meth)acrylic acid ester having an unsubstituted C1 to C10 alkyl group. Specifically, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, iso-butyl (meth)acrylate , Pentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, iso-octyl (meth)acrylate, nonyl ( It may include one or more of meth)acrylate and decyl (meth)acrylate, and these may be included alone or in combination of two or more. For example, the (meth)acrylic monomer having an alkyl group may include one or more of n-butyl (meth)acrylate, t-butyl (meth)acrylate, and iso-butyl (meth)acrylate.

The (meth)acrylic monomer having an alkyl group may be included in 90% to 99% by weight, specifically 93% to 97% by weight in the monomer mixture. In the above range, the mechanical strength of the adhesive film is increased, and durability reliability can be improved.

The (meth)acrylic monomer having an alkyl group may include only one of the aforementioned monomers, but two or more of them may be used in combination. Through this, all functions due to the (meth)acrylic monomer having each alkyl group can be obtained.

In one embodiment, the (meth)acrylic monomer having an alkyl group may be a mixture of a (meth)acrylic monomer having a first alkyl group and a (meth)acrylic monomer having a second alkyl group. The glass transition temperature of the homopolymer of the (meth)acrylic monomer having the second alkyl group is higher than the glass transition temperature of the homopolymer of the (meth)acrylic monomer having the first alkyl group. Therefore, while securing the modulus of the adhesive film for a polarizing plate, it is easy to secure the adhesive force of the adhesive film.

The (meth)acrylic monomer having a first alkyl group may have a homopolymer having a glass transition temperature of -75°C to -35°C, for example, -65°C to -45°C. The (meth)acrylic monomer having a second alkyl group may have a homopolymer having a glass transition temperature of -5°C to 20°C, for example, -2°C to 18°C, 3°C to 13°C. In the above range, it is possible to secure the modulus of the adhesive film while also securing the adhesive force of the adhesive film.

The (meth)acrylic monomer having the first alkyl group and the (meth)acrylic monomer having the second alkyl group may be used as one of the (meth)acrylic monomers having the alkyl group described above if they have a glass transition temperature of the homopolymer in the above-described range. have. For example, a (meth)acrylic monomer having a first alkyl group may be n-butyl (meth)acrylate, and a (meth)acrylic monomer having a second alkyl group may be methyl (meth)acrylate.

(Meth)acrylic monomer having a first alkyl group out of the sum of (meth)acrylic monomer having a first alkyl group and (meth)acrylic monomer having a second alkyl group is 80% to 99% by weight, for example 85% to 99% Weight percent, the (meth)acrylic monomer having a second alkyl group may be included in 1% to 20% by weight, for example, 1% to 15% by weight. In the above range, while maintaining the adhesive force of the adhesive film may have the effect of securing the modulus of the adhesive film.

In the above, the case where two (meth)acrylic monomers having an alkyl group are mixed and included in the monomer mixture has been described. However, the present invention is not limited thereto, and may be included in the monomer mixture with more than one (meth)acrylic monomer having an alkyl group or two or more. In addition, since the modulus at 25°C of the pressure-sensitive adhesive film of the present invention is not influenced by the (meth)acrylic monomer having the above-described alkyl group, the (meth)acrylic system having the alkyl groups having different glass transition temperatures described above is provided by the present invention. It is not necessary to include two types of monomers.

The (meth)acrylic monomer having a hydroxyl group reacts with an isocyanate curing agent to provide the adhesive force of the adhesive film.

The (meth)acrylic monomer having a hydroxyl group is a (meth)acrylic monomer having an alkyl group of C1 to C20 having at least one hydroxyl group, a (meth)acrylic monomer having a cycloalkyl group of C3 to C20 having at least one hydroxyl group, at least one hydroxyl group It may include one or more of the (meth) acrylic monomer having an aromatic group having a C6 to C20. Specifically, the (meth)acrylic monomer having a hydroxyl group is preferably a (meth)acrylic monomer having an alkyl group of C1 to C20 having at least one hydroxyl group, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl ( Meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 1-chloro-2-hydroxypropyl (meth) One or more of acrylates may be included, and these may be included alone or in combination of two or more. For example, the (meth)acrylic monomer having a hydroxyl group is 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxy Butyl (meth) acrylate.

The (meth)acrylic monomer having a hydroxyl group may be included in an amount of 0.01 wt% to 5 wt%, for example, 0.1 wt% to 5 wt%, 0.1 wt% to 1 wt% in the monomer mixture. In the above range, it may be effective to secure the modulus and durability reliability of the adhesive film.

The (meth)acrylic monomer having a carboxylic acid group reacts with a metal chelate-based curing agent to provide the adhesive force of the adhesive film.

The (meth)acrylic monomer having a carboxylic acid group may include (meth)acrylic acid and the like, but is not limited thereto.

The (meth)acrylic monomer having a carboxylic acid group may be included in an amount of 0.01% to 5% by weight, for example, 0.1% to 5% by weight in the monomer mixture. In the above range, it may have an effect of securing or increasing the durability of the adhesive film and maintaining or increasing the adhesive force according to long-term standing.

The monomer mixture may further include a common comonomer known to those skilled in the art in addition to the (meth)acrylic monomer having an alkyl group, the (meth)acrylic monomer having a hydroxyl group, and the (meth)acrylic monomer having a carboxylic acid group. For example, the comonomer may include one or more of a (meth)acrylic monomer having an alicyclic group, a (meth)acrylic monomer having an aromatic group, and a (meth)acrylic monomer having a heteroalicyclic group. As the specific type of the comonomer, a common type known to those skilled in the art can be adopted. The comonomer may be included in the monomer mixture in an amount of 20% by weight or less, for example, 10% by weight or less. In the above range, the effect of the present invention can be produced without affecting the physical properties of the adhesive film for polarizing plates.

The (meth)acrylic copolymer may have an acid value of 0.1 mgKOH/g or more, for example, 5 mgKOH/g to 20 mgKOH/g. In the above range, there may be an effect of excellent durability reliability.

The (meth)acrylic copolymer may have a glass transition temperature of -50°C to 0°C, for example -43°C to -20°C, for example -43°C to -33°C. In the above range, there may be an effect that can simultaneously secure the adhesive durability reliability and adhesive force.

The (meth)acrylic copolymer may have a weight average molecular weight of 500,000 to 1 million, for example, 700,000 to 1,000,000, and 800,000 to 900,000. In the above range, it is possible to secure durability reliability and to enable high-speed coating of 40mpm or more at the time of line coating.

The (meth)acrylic copolymer may have a polydispersity index (PDI) of 4 or less, for example, 2.5 to 3.5. In the above range, a copolymer having a high weight average molecular weight may be distributed, and thus may have an effect on durability reliability.

The (meth)acrylic copolymer may be prepared by polymerizing the monomer mixture by a conventional polymerization method. The polymerization method may include conventional methods known to those skilled in the art. For example, the (meth)acrylic copolymer may be prepared by adding an initiator to the monomer mixture, followed by conventional copolymer polymerization such as suspension polymerization, emulsion polymerization, solution polymerization, and the like. The polymerization temperature may be 65°C to 70°C, and the polymerization time may be 6 hours to 8 hours. The initiator is an azo-based polymerization initiator; And/or peroxides such as benzoyl peroxide or acetyl peroxide.

The pressure-sensitive adhesive composition may include a solvent. The solvent improves the coating properties of the pressure-sensitive adhesive composition and can inhibit the self-curing reaction of the pressure-sensitive adhesive composition. Solvents can be used conventional solvents known to those skilled in the art. For example, the solvent may include one or more of methyl ethyl ketone, ethyl acetate, and toluene.

The pressure-sensitive adhesive composition may further include one or more of a reworking agent, a curing catalyst, an antistatic agent, and a curing catalyst.

The rework agent increases the rework property of the adhesive film, and may include a polysiloxane oligomer, a polyether-modified silicone oil, or a mixture containing the same. The rework agent may be included in an amount of 0.001 part by weight to 5 parts by weight, and specifically 0.005 part by weight to 1 part by weight based on 100 parts by weight of the (meth)acrylic copolymer. In the above range, it is possible to prevent an increase in adhesive strength over time of the adhesive film for a polarizing plate.

The antistatic agent suppresses the generation of static electricity during rework of the adhesive film, and may include a conventional antistatic agent. The antistatic agent may be included in an amount of 0.001 part by weight to 5 parts by weight, specifically 0.1 part by weight to 3 parts by weight with respect to 100 parts by weight of the (meth)acrylic copolymer. In the above range, it is possible to provide an antistatic function without affecting the physical properties of the adhesive film for polarizing plates.

The curing catalyst may be a boron-based compound, for example, a boron trifluoride complex, specifically an etherate of boron trifluoride, a tetrahydrofuran complex of boron trifluoride (BF ₃ -THF), Aniline complex of boron trifluoride (BF ₃ -Aniline), specifically BF ₃ ·O(CH ₃ ) ₂ (boron trifluoride dimethyl etherate), BF ₃ ·O(C ₂ H ₅ ) ₂ (boron trifluoride diethyl etherate); Phosphine-based compounds such as triphenylphosphine, tributylphosphine, tri(p-methylphenyl)phosphine, tri(nonylphenyl)phosphine, triphenylphosphine/triphenylborate, tetraphenylborate, etc.; Secondary or tertiary amine compounds such as triethylamine, benzyldiethylamine or alpha-tertiary amine compounds such as benzyldimethylamine (eg KH-30, Kukdo); Imidazole compounds such as 2-methylimidazole, 2-phenylimidazole, or 2-phenyl-4-methylimidazole; Sulfonic acid-based compounds, for example, paratoluenesulfonic acid, benzenedodecylsulfonic acid, naphthalenesulfonic acid, naphthalene disulfonic acid, methanesulfonic acid, methanedisulfonic acid, phenolsulfonic acid and the like. The curing catalyst may be included in an amount of 0.001 part by weight to 5 parts by weight, and specifically 0.001 part by weight to 1 part by weight based on 100 parts by weight of the (meth)acrylic copolymer. In the above range, there is an effect of reducing the curing speed.

The pressure-sensitive adhesive composition may contain conventional additives. Additives may include ultraviolet absorbers, antioxidants, plasticizers, and the like. The additive may be included as 0.001 part by weight to 5 parts by weight, specifically 0.01 part by weight to 1 part by weight with respect to 100 parts by weight of the (meth)acrylic copolymer. In the above range, an additive effect can be obtained without affecting the physical properties of the adhesive film for polarizing plates.

The pressure-sensitive adhesive composition may have a viscosity of 1,000 cPs to 4,000 cPs at 25°C. In the above range, the thickness of the pressure-sensitive adhesive film may be easy, there is no stain on the pressure-sensitive adhesive film, and the coated surface may have a uniform effect.

The adhesive film for a polarizing plate is optically transparent and can be used in an optical display device. Specifically, the adhesive film may have a light transmittance of 85% or more and more specifically 85% to 95% at a wavelength of 380 nm to 780 nm.

The adhesive film for polarizing plates may have a thickness of 100 μm or less, specifically 5 μm to 50 μm. In the above range, it can be used in an optical display device.

The pressure-sensitive adhesive film for a polarizing plate may be prepared by coating and drying the pressure-sensitive adhesive composition at a predetermined thickness, followed by aging at constant temperature and humidity of 25°C to 35°C and relative humidity of 30% to 60%, but is not limited thereto.

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

The polarizing plate of the present invention may include an adhesive film for a polarizing plate according to embodiments of the present invention. The polarizing plate of the present invention may be prepared by adhering an adhesive film for a polarizing plate according to embodiments of the present invention to one side of the polarizing plate or coating the adhesive composition for the polarizing plate to a predetermined thickness on one side of the polarizing plate, followed by aging.

The optical display device of the present invention may include the adhesive film of the present invention or the polarizing plate of the present invention. The optical display device may include a liquid crystal display device and an organic light emitting display device, but is not limited thereto. In addition, the optical display device of the present invention may also include a flexible device.

The polarizing plate may include a polarizer, an optical film formed on at least one surface of the polarizer, and an adhesive film formed on at least one surface of the optical film. The polarizer and the optical film are according to conventional contents known to those skilled in the art. The polarizing plate may have a thickness of 25 μm to 100 μm, specifically 50 μm to 85 μm. In the above range, it can be used in an optical display device. The polarizing plate may include a polarizer, an optical film formed on at least one surface of the polarizer, and an adhesive film formed on the optical film. The optical film is an optically transparent resin film, and may include a cellulose-based film including triacetyl cellulose, a polyester film including polyethylene terephthalate, a polycarbonate film, an acrylic film, a cycloolefin polymer film, and the like.

Hereinafter, the configuration and operation of the present invention will be described in more detail through preferred embodiments of the present invention. However, this is presented as a preferred example of the present invention and cannot be interpreted as limiting the present invention in any sense.

Manufacturing example One

87 parts by weight of n-butyl acrylate, 10 parts by weight of methyl acrylate, 1 part by weight of 2-hydroxyethyl methacrylate, and 2 parts by weight of acrylic acid in a 1 L reactor in which a nitrogen gas is refluxed and temperature control is easily installed. The containing monomer mixture was added and 100 parts by weight of ethyl acetate was added as a solvent. After that, nitrogen gas was added for 1 hour to remove oxygen to replace the reactor, and the temperature was maintained at 62°C. After uniformly stirring the monomer mixture, 0.07 parts by weight of azobisisobutyronitrile (AIBN) was added as a reaction initiator and reacted for 8 hours to prepare an acrylic copolymer (800,000 to 900,000 weight average molecular weight).

The specifications of the components used in the following examples and comparative examples are as follows.

(A) (meth) acrylic copolymer: (meth) acrylic copolymer of Preparation Example 1

(B1) isocyanate-based crosslinking agent: CK-101 (NCI, solid content 47%, toluene diisocyanate (TDI)-based trifunctional)

(B2) Metal chelate-based crosslinking agent: CK-401E (NCI, solid content 3.2%, aluminum-containing trifunctional crosslinking agent)

(B3) Epoxy clock crosslinking agent: CK201D (NCI, solid content 5%, tetrafunctional)

(B4) Aziridine-based crosslinking agent: PZH-100 (MENADIONA, N,N-hexamethylenebis(2-methyl-1-aziridinecarboxamide, solid content 19%)

(C) Silane coupling agent monomer: KBM-403 (Shinyetsu Chemical Co., epoxy monomer type methoxysilane, 3-glycidoxypropyl trimethoxysilane, solid content 100%)

(D) Silane coupling agent oligomer: CK-842 (NCI, epoxy-based oligomer type methoxy silane, solid content 100%)

(E) Interface modifier: CK-843A (NCI, epoxy low molecular weight silicone oil, solid content 10%)

Example One

Based on the solid content, (A) 100 parts by weight of the acrylic copolymer of Preparation Example 1, (B1) 14.6 parts by weight of an isocyanate-based crosslinking agent, (B2) 0.19 parts by weight of a metal chelating-based crosslinking agent, (C) 0.15 parts by weight of a silane coupling agent monomer , (D) silane coupling agent oligomer 0.48 parts by weight, (E) interface modifier 0.015 parts by weight to prepare a mixture. In consideration of coating properties and solid content for high-speed coating, 30 parts by weight of methyl ethyl ketone solvent was added to 100 parts by weight of the mixture, diluted, and stirred for 60 minutes to prepare an adhesive composition.

After applying the prepared pressure-sensitive adhesive composition on a release film (polyethylene terephthalate film, thickness: 35 μm, RPK-201, Toray advanced material), it was dried at 90° C. for 4 minutes, and then the thickness became 26 μm and the room temperature condition (23° C., Aged at 55% relative humidity) for 4 days to prepare an adhesive layer

Example 2 to Example 5

In Example 1, the adhesive layer was formed in the same manner as in Example 1, except that the content of each component in the mixture was changed as shown in Table 1 below. Table 1 below shows the input amount of each component in the pressure-sensitive adhesive composition and shows the content of the solid content added excluding the solvent.

Comparative example 1 to Comparative example 5

In Example 1, the adhesive layer was formed in the same manner as in Example 1, except that the type and/or content of each component in the mixture was changed as shown in Table 1 below.

The physical properties of Table 1 below were evaluated for the pressure-sensitive adhesive layers of Examples and Comparative Examples.

(1) Initial adhesive strength (AS1, unit: gf/25mm): The adhesive strength of the pressure-sensitive adhesive layer was evaluated in accordance with JIS 2107 standards. After peeling the release film from the pressure-sensitive adhesive layer prepared in Examples and Comparative Examples, the pressure-sensitive adhesive layer was laminated to a glass plate, cut into a rectangular specimen having a width x length (25 mm x 100 mm), and a 30 kgf load cell (load from a tensile analyzer). cell), after connecting the adhesive film for polarizing plate and the glass plate to the upper jig and the lower jig, respectively, the load at the time of peeling of the adhesive layer from the glass plate was measured at a measurement temperature of 25°C, a peeling angle of 180°, and a tensile speed of 300 mm/min.

(2) Adhesion over time (AS2, unit: gf/25mm): After the release film was attached to the pressure-sensitive adhesive layer prepared in Examples and Comparative Examples, the mold release film was left at 25°C and relative humidity at 55% for 180 days. Peeling, the adhesive force was measured in the same manner as in AS1.

(3) Peel force to release film (PS, unit: gf/25mm): Peel force to release film was evaluated according to JIS 2107 standards. The adhesive layer and the release film prepared in Examples and Comparative Examples were cut into rectangular specimens of width x length (25 mm x 100 mm), and an adhesive film for polarizing plates and a release film in a load cell of 30 kgf in a tensile tester (Texture Analyzer). Was connected to the upper jig and the lower jig, respectively, and the load at the time of peeling of the pressure-sensitive adhesive layer from the release film was measured at a measurement temperature of 25°C, a peel angle of 180°, and a tensile speed of 300 mm/min.

(4) Modulus (G' (25 °C), G'(85 °C), Unit: MPa): A plurality of adhesive layers having a thickness of 26 µm of Examples and Comparative Examples were overlapped to prepare a specimen having a thickness of 0.8 mm, and Using the Physica MCR501 manufactured by Anton Paar for the specimens, the temperature was increased from 0 rad to 10 ºC at a rate of 10 ºC/min by a temperature sweep test (strain 5%, normal force 1.5 N) at 10 rad/s. Storage modulus was measured at 25°C or 85°C.

(5) Initial Reliability (Initial Reliability 1, Initial Reliability 2): The polyvinyl alcohol film was stretched three times at 60°C, adsorbed to iodine, and then stretched 2.5 times in a 40°C aqueous boric acid solution to obtain a polarizer (thickness: 23㎛). It was prepared. A triacetyl cellulose (TAC) film (thickness: 80 µm) was adhered to both surfaces of the prepared polarizer using an adhesive to prepare a polarizing plate. The prepared pressure-sensitive adhesive layer was laminated on one side of the TAC film (thickness: 42 μm) of the polarizing plate in the state where the release film was adhered, and aged at 23° C. and relative humidity of 55% for 4 days. The polarizing plate having a release film and an adhesive film was cut into a rectangular shape with a width x length (100 mm x 175 mm, MD x polarizer TD of the polarizer) and laminated to a glass plate to prepare a specimen by applying a pressure of 4 kg to 5 kg.

The specimens prepared in relation to heat resistance were left at 85° C. for 500 hours, and then left at room temperature for 1 hour or more, and observed with a visual microscope or microscope. It evaluated according to the following criteria. The specimens prepared in relation to heat and humidity resistance were left at 60° C. and 95% relative humidity for 500 hours, and then left at room temperature for 1 hour or more, and observed under a microscope or microscope. Evaluation was made according to the following criteria

○: No bubbles or peeling phenomenon.

△: There are some bubbles or peeling phenomenon.

X: There is a bubble or peeling phenomenon.

(6) Long-term reliability (reliability 2): Specimens prepared in the same manner as in (5) were left for 180 days at 25°C and relative humidity of 55%. Then, the heat-resistant reliability and the heat-resistant and heat-resistant reliability were evaluated in the same manner as in (5).

(7) Light leakage: In the same manner as in (5), a polarizing plate was manufactured in a state where the pressure-sensitive adhesive layer and the release film were adhered. Lamination was performed on both surfaces of the glass plate (thickness: 1 mm) so that the absorption axes of the polarizers were perpendicular to each other. And it was left at 85°C for 500 hours, and then left at 25°C for 2 hours. After driving the IPS mode liquid crystal display for the specimen, the luminance of the front of the display panel was measured at a height of 1 m using a luminance measurement device (RISA, Hiland). Specifically, the luminance (c) at the center of the panel and the luminance (a), (b), (d), and (e) at the corners where light leakage appears are measured. The luminance measurement point was set such that the measurement radius near each vertex of the panel was 0.5 cm as shown in FIG. 1. In Fig. 1, ⓐⓑⓒⓓⓔ indicates a luminance measurement point. The degree of light leakage (ΔL) was quantified according to Equation 3 below. The lower the ΔL, the better the light leakage. It evaluated according to the following evaluation criteria.

[Equation 3]

△L = ｜(a + b + d + e)/4-c｜

(In Equation 3, a, b, d, and e are luminance measured at the luminance measurement point ⓐⓑⓓⓔ (high luminance area) in FIG. 1, respectively, and c (low luminance region) is the luminance measurement point ⓒ in FIG. Luminance.

(8) Cleavage: A polarizing plate having a release film and an adhesive film was prepared in the same manner as in (5), and was cut with a Thompson Carter in length x width (400 mm x 250 mm). The degree of peeling of the adhesive layer from the cut surface was reported and evaluated according to the following criteria.

○: There is no degree of adhesive missing on the cut surface.

△: There is some degree of adhesive missing on the cut surface.

×: There is a large amount of adhesive missing on the cut surface.

Example Comparative example One 2 3 4 5 One 2 3 4 5 (A) 100 100 100 100 100 100 100 100 100 100 (B1) 14.6 14.6 14.6 14.6 14.6 14.6 14.6 14.6 14.6 14.6 (B2) 0.19 0.2 0.23 0.2 0.2 0 0 0.2 0.2 0.19 (B3) 0 0 0 0 0 0.2 0 0 0 0 (B4) 0 0 0 0 0 0 0.2 0 0 0 (C) 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0 0.15 0.15 (D) 0.48 0.48 0.48 0.37 0.48 0.48 0.48 0.48 0 0.48 (E) 0.015 0.015 0.015 0.015 0.011 0.015 0.015 0.015 0.015 0 AS1 280 270 260 265 260 270 235 210 240 250 AS2 300 290 270 270 260 170 130 190 200 210 Equation 1 20 20 10 5 0 -100 -105 -20 -40 -40 PS 1.7 1.8 1.8 1.6 1.5 1.8 1.7 1.8 1.9 1.4 G'
(25℃) 0.82 0.89 0.9 0.88 0.87 0.84 0.9 0.87 0.88 0.82 G'
(85℃) 0.35 0.36 0.38 0.36 0.35 0.35 0.37 0.34 0.35 0.34 Initial reliability 1 ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ Initial reliability 2 ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ Long-term reliability 1 ○ ○ ○ ○ ○ △ △ × △ △ Long-term reliability 2 ○ ○ ○ ○ ○ × △ × △ △ Light 0.2 0.19 0.21 0.22 0.2 0.21 0.23 0.22 0.19 0.2 Cutting ○ ○ ○ ○ ○ △ ○ ○ ○ ○

As shown in Table 1, the adhesive film for polarizing plates of the present invention is a hard type adhesive film for polarizing plates, and the adhesive strength is maintained or the adhesive strength is increased compared to the initial state even after being left for a long period of time, thereby providing excellent long-term durability reliability and durability reliability in the initial state. This was excellent, and was excellent in cutting property and light leakage prevention effect.

On the other hand, in the adhesive film of the present invention, the adhesive film of the comparative example lacking at least one of a (meth)acrylic copolymer, an isocyanate-based crosslinking agent, a metal chelate-based crosslinking agent, a silane coupling agent oligomer, a silane coupling agent monomer and an interface modifier is I couldn't get all the effects.

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

Claims (18)

An adhesive film for a polarizing plate formed of a pressure-sensitive adhesive composition for a polarizing plate comprising a (meth)acrylic copolymer, an isocyanate crosslinking agent, a metal chelate crosslinking agent, a silane coupling agent oligomer, a silane coupling agent monomer, and an interface modifier.
The adhesive film for a polarizing plate according to claim 1, wherein the adhesive film for a polarizing plate has a difference in adhesive strength according to Equation 1 below from 0 gf/25 mm to 50 gf/25 mm:
<Equation 1>
Difference in adhesion = AS2-AS1
(In the above formula 1, AS1 is the adhesive force of the adhesive film for the polarizing plate at 25°C to the glass plate (unit: gf/25mm)
AS2 is the adhesive film for the polarizing plate at 25° C. and relative humidity of 55% for 180 days, and then at 25° C., the adhesive strength of the adhesive film for the polarizing plate to the glass plate (unit: gf/25 mm).
The adhesive film for polarizing plates according to claim 1, wherein the adhesive film for polarizing plates has a modulus of 0.8 MPa or higher at 25°C.
The adhesive film for polarizing plates according to claim 1, wherein the adhesive film for polarizing plates has a modulus of 0.3 MPa or more at 85°C.
The adhesive film for a polarizing plate according to claim 1, wherein the adhesive film for the polarizing plate has a modulus difference according to the following Equation 2 of 1.0 MPa or less:
[Equation 2]
Modulus difference = G'(25℃)-G'(85℃)
(In the formula 2, G'(25 °C) is storage modulus at 25 °C of the adhesive film for polarizing plates (unit: MPa),
G'(85°C) is the storage modulus at 85°C of the adhesive film for polarizing plates (unit: MPa).
The adhesive film for polarizing plates according to claim 1, wherein the adhesive film for polarizing plates has an AS1 and an AS2 of 200 gf/25 mm or more in Equation 1.
According to claim 1, The isocyanate-based crosslinking agent: The weight ratio of the metal chelate-based crosslinking agent will be included in 50:1 to 100:1, the adhesive film for polarizing plates.
The adhesive film for polarizing plates according to claim 1, wherein the silane coupling agent monomer comprises a silane coupling agent monomer having an epoxy structure.
The adhesive film for polarizing plates according to claim 1, wherein the silane coupling agent oligomer comprises an epoxy-based silane coupling agent oligomer.
The adhesive film for polarizing plates according to claim 1, wherein the interface modifier comprises an epoxy-based modified silicone oil.
According to claim 1, The pressure-sensitive adhesive composition for a polarizing plate
100 parts by weight of the (meth) acrylic copolymer
10 to 30 parts by weight of the total amount of the isocyanate crosslinking agent and the metal chelate crosslinking agent,
The silane coupling agent oligomer 0.001 parts by weight to 5.0 parts by weight
0.001 part by weight to 1 part by weight of the silane coupling agent monomer, and
It comprises 0.001 parts by weight to 1.0 parts by weight of the interface modifier, the adhesive film for a polarizing plate.
The adhesive film for polarizing plates according to claim 1, wherein the polarizing plate adhesive film has a surface energy of 40 mJ/m ² or less measured at 25° C. after 180 days at 25° C. and 55% relative humidity.
The method of claim 1, wherein the (meth) acrylic copolymer comprises a copolymer of a monomer mixture comprising a (meth) acrylic monomer having an alkyl group, a (meth) acrylic monomer having a hydroxyl group and a (meth) acrylic monomer having a carboxylic acid group. That is, the adhesive film for a polarizing plate.
The method of claim 13, wherein the monomer mixture is 90% to 99% by weight of the (meth)acrylic monomer having the alkyl group, 0.01% to 5% by weight of the (meth)acrylic monomer having the hydroxyl group, and (meth) having the carboxylic acid group. ) Acrylic monomer containing 0.01 to 5% by weight of the adhesive film for a polarizing plate.
The adhesive film for polarizing plates according to claim 1, wherein the adhesive film for polarizing plates further comprises a rework agent.
The adhesive film for a polarizing plate according to claim 15, wherein the rework agent contains polyether-modified silicone oil.
A polarizing plate comprising the adhesive film for polarizing plates according to any one of claims 1 to 16.
An optical display device comprising the polarizing plate of claim 17.

Images