KR20140107592A - Optical member adhesive composition, adhesive sheet using same, optical member provided with adhesive layer, and flat panel display - Google Patents

Abstract

An object of the present invention is to provide a pressure-sensitive adhesive composition for optical members which is excellent in dimensional stability and exhibits excellent light leakage preventing performance and durability even under a humid environment. The present invention relates to an optical member comprising a specific amount of a (meth) acrylic copolymer (A) and a crosslinking agent (B) obtained by copolymerizing specific monomer components (a-1) to To a pressure-sensitive adhesive composition.

Description

TECHNICAL FIELD [0001] The present invention relates to a pressure-sensitive adhesive composition for an optical member, an adhesive sheet using the same, an optical member with a pressure-sensitive adhesive layer, and a flat panel display.

The present invention relates to a pressure-sensitive adhesive composition for an optical member which is excellent in dimensional stability and wet heat durability and can effectively prevent light leakage or peeling in a high temperature and high humidity environment, and an adhesive sheet, an optical member with a pressure- .

With respect to pressure-sensitive adhesives for the flat panel display (FPD) field, demands for high quality, such as high image quality and high durability, are increasing with the enlargement of displays and the spread of LED methods.

For example, a liquid crystal display (LCD) classified as an FPD is formed of a liquid crystal panel, a backlight, and peripheral circuits. The liquid crystal panel is typically composed of a polarizing plate, a glass substrate having a transparent electrode, a color filter, and the like, and the glass substrate has a configuration in which the liquid crystal is sandwiched.

Since the polarizing plate has a multilayer structure of different materials and each material has different physical and chemical properties, the degree of dimensional change of each layer due to shrinkage or swelling is different under a high temperature and high humidity environment, The difference is also great. For this reason, the polarizing plate is insufficient in dimensional stability as a whole.

Due to this dimensional change, various influences occur in various performances represented by light leakage and durability as a whole of the polarizing plate. It is also known that the above light leakage and durability are affected by adhesion of optical films such as a polarizing plate and adhesion of a pressure-sensitive adhesive used for bonding a glass substrate and a polarizing plate.

In the present situation, the combination of the polarizing plate type and the pressure-sensitive adhesive species copes with various required performances such as the light leakage and durability. However, the required performance is, as described above, , And high durability.

In order to solve the light leakage caused by the dimensional change of the polarizing plate and the peeling in the high temperature and high humidity environment, attention is paid to various properties such as the hard and optical properties of the polymer constituting the pressure sensitive adhesive, Studies have been made in order to realize light leakage preventing performance and securing high durability.

For example, the pressure-sensitive adhesive, which focuses attention on the hard properties, is not deformed well under a humid environment and foaming or the like hardly occurs. Therefore, the pressure-sensitive adhesive exhibits excellent resistance to stress and durability during shrinkage of the polarizing plate, It was easy. However, when the FPD is enlarged, a problem such as light leakage or slight foaming which is not a problem in the previous size becomes noticeable. For this reason, the conventional pressure sensitive adhesives can not sufficiently cope with such improvement of the required characteristics.

As such a pressure-sensitive adhesive, for example, Patent Document 1 discloses a method of copolymerizing a specific (meth) acrylate ester (A-1), an unsaturated monomer having an aromatic ring (A-2) and an unsaturated monomer having a polar functional group Discloses a pressure-sensitive adhesive composition containing a (meth) acrylic copolymer (A), an ionic compound (B) and a crosslinking agent (C).

(A-1) is exemplified by n-butyl acrylate, and examples of the above (A-2) are 2-phenoxyethyl (meth) acrylate , And examples of the above (A-3) include acrylic acid and 2-hydroxyethyl (meth) acrylate.

Further, Patent Document 2 contains a homopolymer Tg (meth) acrylic acid ester monomer is less than -30 ℃ of the polymer (a _1), Tg of the compound having the vinyl group or higher -30 ℃ homopolymers (a _2), and a specific functional group monomers ( consisting of a ₃₎ (meth) discloses a polarizing plate having an adhesive layer comprising the pressure-sensitive adhesive containing the acrylic copolymer (a) and a cross-linking structure polyfunctional compound (B) capable of forming a.

Examples of (a ₁ ) include n-butyl acrylate. Examples of (a ₂ ) include t-butyl acrylate. Examples of (a ₃ ) include (meth) -Hydroxyethyl (meth) acrylate.

However, in the pressure-sensitive adhesives disclosed in these documents, as described above, it is not possible to cope with the presently required high-level characteristics.

Japanese Laid-Open Patent Publication No. 2010-66755 Japanese Laid-Open Patent Publication No. 2006-301572

It is therefore an object of the present invention to provide a pressure-sensitive adhesive composition for an optical member exhibiting excellent dimensional stability and exhibiting excellent light leakage preventing performance and durability even under a humid environment.

The inventors of the present invention have conducted studies on the hard properties of the pressure-sensitive adhesive, the optical compensation function, and the pressure-sensitive adhesive composition, which has paid attention to the crosslinking system. As a result, the present inventors have found that the use of monomers, which give flexibility to a polymer, (Meth) acrylic copolymer obtained by using a monomer capable of imparting an optical compensation function and a monomer giving a crosslinking property to a polymer in a specific ratio is crosslinked at an appropriate crosslinking degree setting, It is possible to provide a pressure-sensitive adhesive composition for an optical member which is excellent in stability and moist heat durability and can effectively prevent light leakage or peeling in a high temperature and high humidity environment.

That is, the present invention relates to (A): (meth) acrylic copolymers obtained by copolymerizing the following (a-1) to (a-4)

(meth) acrylate having a glass transition temperature of -40 占 폚 or less and no aromatic ring (a-1) 40 to 94.9% by weight,

(meth) acrylate having a glass transition temperature of 0 占 폚 or higher and having no aromatic ring in the homopolymer (a-2) is 0.1 to 50% by weight,

0.1 to 25% by weight of a (meth) acrylic acid ester having an aromatic ring (a-3)

(a-4) 0.1 to 6% by weight of a (meth) acrylic monomer having two or more polar functional groups and / or two or more different (meth) acrylic monomers having one polar functional group,

(Provided that the sum of (a-2) and (a-3) is 5 to 59.9 wt%

The polar functional group is selected from a carboxyl group, a hydroxyl group, an amino group, an amide group and an epoxy group,

(a-1) to (a-4) is 100% by weight)

(B): 0.01 to 3 parts by weight of a crosslinking agent per 100 parts by weight of the (meth) acrylic copolymer (A).

The copolymerization ratio of the (meth) acrylic acid ester (a-2) is preferably 10 to 40% by weight.

The (meth) acrylic acid ester (a-2) may be at least one compound selected from the group consisting of methyl (meth) acrylate, i-butyl methacrylate, t- butyl (meth) acrylate, cyclohexyl (meth) acrylate and isobornyl And at least one selected from the group consisting of the above-mentioned compounds.

The (meth) acrylic acid ester (a-2) is preferably t-butyl (meth) acrylate.

The copolymerization ratio of the (meth) acrylic acid ester (a-1) is preferably 50 to 90% by weight.

The (meth) acrylate ester (a-1) is preferably selected from the group consisting of n-butyl acrylate, n-pentyl acrylate, isopentyl acrylate, hexyl acrylate, heptyl acrylate, isoamyl acrylate, (Meth) acrylate, n-decyl methacrylate, n-dodecyl methacrylate, n-tridecyl (meth) acrylate, n-octyl acrylate, isooctyl acrylate, n-nonyl acrylate, isononyl acrylate, (Meth) acrylate, methoxyethyl acrylate, methoxypolyethylene glycol acrylate, and ethoxyethoxyethyl acrylate.

The (meth) acrylic ester (a-3) is preferably at least one selected from the group consisting of benzyl (meth) acrylate, phenoxyethyl (meth) acrylate ester represented by the following general formula (1) .

[Chemical Formula 1]

In the formula (1), R ₀ is hydrogen or a methyl group, R ₁ is a group represented by (CH ₂ CH ₂ O) _n (n is an integer of 1 to 20), m is an integer of 1 to 5, R ₂ is hydrogen, an alkyl group having 1 to 9 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an aralkyl group having 7 to 11 carbon atoms. When m is 2 or more, the plurality of R _{2 s} present may be the same or different.

The copolymerization ratio of the (meth) acrylic monomer (a-4) is preferably 1 to 6% by weight.

It is preferable that the ratio of the measured value at 60 캜 to the measured value at 23 캜 is 1.05 to 2.00 in the case of performing the following micro creep test on the pressure-sensitive adhesive composition for optical member.

(Micro creep test)

The pressure-sensitive adhesive composition for an optical member was coated on a peeled polyester film and dried to prepare a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having a thickness of 25 占 퐉;

The pressure sensitive adhesive sheet is bonded to a polarizing plate constituted by TAC (triacetyl cellulose) - PVA (polyvinyl alcohol) - TAC so that the pressure sensitive adhesive layer is in contact with the polarizing plate, thereby producing an adhesive working polarizing plate for evaluation;

The pressure-sensitive adhesive polarizing plate for evaluation was cut into a width of 10 mm and a length of 100 mm, and the peeled polyester film was peeled off so that the pressure-sensitive adhesive layer came into contact with the glass, And the resultant is used as an evaluation adhesive process polarizing plate test piece;

The test piece for pressure-sensitive adhesive polarizing plate for evaluation was subjected to an autoclave treatment (50 DEG C, 5 atm) and quiescently stopped at 23 DEG C / 50% RH atmosphere for 24 hours;

Next, the test piece is set in the chamber BOX of the micro creep measuring instrument at a length of 15 mm of the fixing portion;

After heating the inside of the chamber BOX to the measurement temperature and stopping at the measurement temperature for 40 minutes, the polarizing plate for evaluation and the polarizing plate for evaluation in the test piece were placed at a tensile load of 800 g and a tensile time of 1000 seconds And is stretched in parallel with the adhesive surface and in the longitudinal direction of the polarizing plate;

The distance (mm) of the deviation of the fusion of the glass and the polarizing plate in the test piece is measured.

The pressure-sensitive adhesive composition for an optical member of the present invention preferably further contains 0.01 to 0.5 parts by weight of a silane coupling agent based on 100 parts by weight of the (meth) acrylic copolymer (A).

The composition preferably further contains 0.01 to 3 parts by weight of an antistatic agent per 100 parts by weight of the (meth) acrylic copolymer (A).

By using the pressure-sensitive adhesive composition for an optical member of the present invention as a component of a pressure-sensitive adhesive layer, a pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer formed on a base film can be obtained.

The optical member with a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer contains the pressure-sensitive adhesive composition for an optical member according to the present invention, is also included in the scope of the present invention. do.

The flat panel display of the present invention is characterized by having the optical member with the pressure-sensitive adhesive layer.

INDUSTRIAL APPLICABILITY According to the present invention, there is provided a pressure-sensitive adhesive composition for an optical member which is excellent in dimensional stability and moist heat durability and can effectively prevent light leakage and peeling in a high temperature and high humidity environment and an adhesive sheet using the composition, Is provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing a distance d from a corner of a light leakage generating portion in measurement of a light leakage size in the embodiment. FIG.
Fig. 2 is a schematic diagram showing a method of measuring the photoelastic coefficient in the examples. Fig.

Hereinafter, the pressure-sensitive adhesive composition for an optical member of the present invention (hereinafter simply referred to as " composition of the present invention ") and the pressure-sensitive adhesive sheet using it, the optical member with a pressure-sensitive adhesive layer, and the flat panel display will be described in detail in this order. In the present specification, (meth) acryl means methacryl or acrylic, and (meth) acrylate means methacrylate or acrylate.

[Pressure sensitive adhesive composition for optical member]

[(A) (Meth) acrylic copolymer]

The (meth) acrylic copolymer (A) which is a component of the composition of the present invention is obtained by copolymerizing specific monomer components (a-1) to (a-4) at a specific ratio as described above. Hereinafter, each of these monomers will be described.

(Meth) acrylic acid esters having a glass transition temperature of the homopolymer of (a-1) -40 ° C or less and no aromatic ring,

With respect to the (meth) acrylic acid ester (a-1) used in the present invention, the glass transition temperature (hereinafter, abbreviated as Tg) of the homopolymer is -40 占 폚 or less.

To in the present specification the Tg is one, a test piece (homopolymer) for measuring the Tg in the N ₂ atmosphere, a range of -60 to 180 ℃ ℃, raising the temperature at a rate of 10 ℃ / minute unless otherwise noted, DSC (Differential scanning calorimeter DSC8230 manufactured by Rigaku Corporation). The measurement is carried out in accordance with JIS K 7121 (Transition Temperature Measurement Method of Plastics).

(Meth) acrylic acid esters having a Tg of -40 占 폚 or less (for example, a homopolymer having a Tg of -40 占 폚 or less) may be used as the crosslinking agent obtained by crosslinking the pressure- (meth) acrylic copolymer (A) is appropriately imparted with flexibility by using the (meth) acrylic copolymer (a-1).

In addition, the (meth) acrylate ester (a-1) does not have an aromatic ring. If the aromatic ring is present, flexibility may not be imparted to the (meth) acrylic copolymer (A), and the balance with the control of the optical compensation function by the (meth) acrylic ester (a-3) In some cases.

In the present specification, the aromatic ring refers to a structure in which atoms having π electrons are arranged in a ring form and satisfies the Fwankel rule, and the π electrons are non-stationary, and the ring has a planar structure.

Examples of such (meth) acrylate esters (a-1) include n-butyl acrylate, n-pentyl acrylate, isopentyl acrylate, hexyl acrylate, heptyl acrylate, isoamyl acrylate, (meth) acrylate, n-dodecyl methacrylate, n-dodecyl (meth) acrylate, n-octyl acrylate, Tridecyl (meth) acrylate, methoxyethyl acrylate, methoxypolyethylene glycol acrylate, and ethoxyethoxyethyl acrylate.

Of these, n-butyl acrylate and 2-ethylhexyl acrylate are preferred from the viewpoint of achieving balance between hard properties and flexibility and achieving excellent stress resistance.

The (meth) acrylic ester (a-1) described above can be used singly or in combination of two or more kinds.

<(A-2) (meth) acrylate ester having a homopolymer having a glass transition temperature of 0 ° C or more and no aromatic ring>

With regard to the (meth) acrylic acid ester (a-2) used in the present invention, the Tg of the homopolymer is 0 캜 or higher. The (meth) acrylic acid ester (a-2) having a high Tg of the homopolymer imparts excellent hard properties to the (meth) acrylic copolymer (A), contributing to the high dimensional stability of the pressure- do.

Further, the (meth) acrylic acid ester (a-2) does not have an aromatic ring. The presence of the aromatic ring may cause a problem in balance with the control of the optical compensation function by the (meth) acrylic acid ester (a-3) to be described later.

Examples of such (meth) acrylate ester (a-2) include methyl (meth) acrylate, propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t- Hexyl (meth) acrylate, isobornyl (meth) acrylate and stearyl (meth) acrylate.

Among them, from the viewpoint of achieving excellent hard properties, it is preferable to use at least one of (meth) acrylate, (Meth) acrylate is particularly preferable, and t-butyl (meth) acrylate is particularly preferable.

The (meth) acrylic ester (a-2) described above can be used singly or in combination of two or more kinds.

<(Meth) acrylate ester having (a-3) aromatic ring>

(Meth) acrylic acid ester (a-3) has an aromatic ring and contains the structural unit derived from the (meth) acrylic ester (a-3) can do. Thus, even when the optical member is adhered by using the pressure-sensitive adhesive composition for an optical member of the present invention and a slight light leakage occurs under a humid environment, the light leakage is suppressed by the optical compensation function.

Examples of such a (meth) acrylate ester (a-3) include benzyl (meth) acrylate, phenoxyethyl (meth) acrylate represented by the following general formula (1) and derivatives thereof.

(2)

In the formula (1), R ₀ is hydrogen or a methyl group, R ₁ is a group represented by (CH ₂ CH ₂ O) _n (n is an integer of 1 to 20), m is an integer of 1 to 5, R ₂ is hydrogen, an alkyl group having 1 to 9 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an aralkyl group having 7 to 11 carbon atoms. When m is 2 or more, the plurality of R _{2 s} present may be the same or different.

Specific examples of the phenoxyethyl (meth) acrylate ester and derivatives thereof represented by the general formula (1) include phenoxyethyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, phenoxy (poly) ethylene glycol (Meth) acrylate, nonylphenol ethylene oxide adduct (meth) acrylate, and ethoxylated o-phenylphenol (meth) acrylate.

Among these, benzyl (meth) acrylate and phenoxyethyl (meth) acrylate are preferable from the viewpoint of achieving excellent optical compensation function.

The (meth) acrylic ester (a-3) described above can be used singly or in combination of two or more.

<(A-4) (Meth) acrylic monomer having two or more kinds of polar functional groups and / or two or more different kinds of (meth) acrylic monomers having one kind of polar functional group>

The (meth) acrylic monomer (a-4) used in the present invention has a polar functional group, and a crosslinking reaction occurs between this and the crosslinking agent (B) described later, . The polar functional group is a carboxyl group, a hydroxyl group, an amino group, an amide group and an epoxy group. Among them, a hydroxyl group is preferable from the viewpoint of good durability in a humid environment.

The (meth) acrylic monomer (a-4) has two or more kinds of polar functional groups. Due to the presence of a plurality of different kinds of polar functional groups, crosslinking between the (meth) acrylic copolymers (A) , It is considered that a good degree of crosslinking is achieved.

The above-mentioned &quot; having two or more polar functional groups &quot; means that two or more kinds of polar functional groups are present when all the (meth) acrylic monomers (a-4) composed of a plurality of molecules are observed.

For this reason, the (meth) acrylic monomer (a-4) is a kind of monomers in which two or more polar functional groups are present in one molecule of the monomer, and the (meth) acrylic monomer (a- And each of the monomers may have one kind of polar functional group. In the latter case, there are two or more kinds of monomers having different structures, but the polar functional groups possessed by them are not contained in the same case.

In the (meth) acrylic copolymer (A), as the monomer (a-4), only monomers in which two or more kinds of polar functional groups are present in one monomer may be used, and such monomers are not used, Or two or more monomers having a polar functional group may be used.

In the present specification, the (meth) acrylic monomer (a-4) corresponds to any of the (meth) acrylic esters (a-1) to a-4).

Examples of the (meth) acrylic monomers having two or more kinds of polar functional groups described above include hydroxyethyl acrylamide and t-butyl acrylamide sulfonic acid.

As the (meth) acrylic monomers having one kind of polar functional group described above, the following monomers may be mentioned.

(I) a (meth) acrylic monomer having a carboxyl group: (meth) acrylic acid,? -Carboxyethyl (meth) acrylate

(Ii) a (meth) acrylic monomer having a hydroxyl group such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, glycerin mono (Poly) ethylene glycol mono (meth) acrylate, (poly) propylene glycol mono (meth) acrylate,

(Meth) acrylate, (iii) a (meth) acrylic monomer having an amino group such as aminoethyl (meth) acrylate, N, N-dimethylaminoethyl

(Meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N- Methylol propane (meth) acrylamide

(V) (meth) acrylic monomers having an epoxy group: glycidyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate glycidyl ether.

<Other Monomers>

In the present invention, structural units originating from other monomers other than the above monomer components (a-1) to (a-4) are preferably used in the range of not lowering the effect of the present invention Meth) acrylic copolymer (A).

Examples of such other monomers include styrene,? -Methylstyrene, vinyl acetate, vinyl propionate, ethyl acrylate, isobutyl acrylate, 2-ethylhexyl methacrylate, and lauryl acrylate.

&Lt; Process for producing (meth) acrylic copolymer (A)

(Copolymerization ratio of each monomer)

(Meth) acrylic copolymer (A), which is a constituent component of the pressure-sensitive adhesive composition for an optical member of the present invention, comprises the above-described respective monomer components (a-1) to (a-4) In a specific ratio.

The copolymerization ratio of the (meth) acrylic acid ester (a-1) in the (meth) acrylic copolymer (A) is from 40 to 94.9% by weight, preferably from 50 to 90% by weight % to be.

The copolymerization ratio of the (meth) acrylic ester (a-2) in the (meth) acrylic copolymer (A) is from 0.1 to 50% by weight, preferably from 10 to 40% by weight, And preferably 10 to 25% by weight.

The copolymerization ratio of the (meth) acrylic acid ester (a-3) in the (meth) acrylic copolymer (A) is 0.1 to 25% by weight, preferably 5 to 20% by weight from the viewpoint of optical compensation function.

The copolymerization ratio of the (meth) acrylic monomer (a-4) in the (meth) acrylic copolymer (A) is from 0.1 to 6% by weight, preferably from 1 to 6% by weight from the viewpoint of proper crosslinking.

The total copolymerization ratio of the respective monomer components (a-1) to (a-4) is 100% by weight.

The sum of the copolymerization ratios of the (meth) acrylate esters (a-2) and (a-3) is preferably 5 to 59.9 wt% %, Preferably 10 to 50 wt%.

The copolymerization ratio of the other monomers is usually 0 to 5 parts by weight based on 100 parts by weight of the total of the monomers (a-1) to (a-4).

(Process for producing (meth) acrylic copolymer (A)

(Meth) acrylic copolymer (A) is obtained by copolymerizing the respective monomer components (a-1) to (a-4) and, if necessary, other monomers by solution polymerization, bulk polymerization, emulsion polymerization, Can be produced by polymerizing by conventionally known polymerization methods. Among these methods, it is preferable to employ a solution polymerization method because the molecular weight of the polymer can be easily adjusted and the impurity content in the reaction system is small.

In the solution polymerization method, an organic solvent is used as a reaction solvent to dissolve or disperse each monomer component forming the (meth) acrylic copolymer (A) in the reaction solvent, and a polymerization initiator is added under stirring to effect a copolymerization reaction Conduct.

Examples of the organic solvent include ester solvents such as ethyl acetate; Ketone solvents such as methyl ethyl ketone, formaldehyde and acetaldehyde; Ether solvents such as dimethyl ether; Aromatic solvents such as toluene and xylene; Alicyclic solvents such as cyclohexane; And aliphatic solvents such as hexane and octane.

These solvents may be used alone or in combination of two or more solvents.

Examples of the polymerization initiator include azo compounds such as 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile) Azo compounds such as azobis-2,4-dimethylvaleronitrile and 1,1'-azobiscyclohexane-1-carbonitrile; Diisopropyl peroxydicarbonate, di-tert-butyl peroxydicarbonate, di-tert-butyl peroxydicarbonate, diisopropyl peroxydicarbonate, di-tert-butyl peroxydicarbonate, -Butyl peroxydicarbonate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, bis (4-butylcyclohexyl) peroxydicarbonate, benzoyl peroxide, di-tert-butyl peroxide, Butyl peroxide, tert-butyl-oxy-2-ethyl hexanoate, and the like. These can be used alone or in combination.

In the solution polymerization method, the reaction temperature of the copolymerization reaction using these reaction solvents and polymerization initiator is usually in the range of 50 to 90 占 폚, preferably 60 to 85 占 폚, and the reaction time is usually 1 to 10 hours , Preferably 2 to 8 hours, and the reaction pressure is usually atmospheric pressure to 0.5 MPa.

<(A) (Meth) Acrylic Copolymer>

When the (meth) acrylic copolymer (A) is crosslinked using a crosslinking agent (B) to be described later to form a crosslinked product excellent in hard properties and optical compensation function, the use of the pressure- Dimensional stability, light leakage prevention performance, and durability under a humid environment can be achieved.

The weight average molecular weight (Mw) of the (meth) acrylic copolymer (A) measured by GPC is usually 500,000 to 2,000,000, preferably 80,000 to 1,800,000, and the copolymer (A) It has adhesion.

The (meth) acrylic copolymer (A) preferably has a glass transition temperature of 0 ° C or lower, more preferably -10 ° C or lower, and particularly preferably -15 ° C to -60 ° C. If the glass transition temperature is higher than 0 占 폚, the adhesiveness of the resulting pressure-sensitive adhesive to the adherend and the flexibility of the pressure-sensitive adhesive layer are lowered, and peeling or lifting from the adherend may occur. The glass transition temperature of the (meth) acrylic copolymer (A) is a value calculated by the following FOX formula.

(Expression of FOX)

1 / Tg = Wa / Tga + Wb / Tgb +

Tg: Glass transition temperature of the (meth) acrylic copolymer (A)

Tga, Tgb, ... : Monomer a, monomer b, ... The glass transition temperature of each homopolymer of

Wa, Wb, ... : Monomer a, monomer b, ... In the (meth) acrylic copolymer (A) of the structural unit derived from each of

The (meth) acrylic monomers (a-1) to (a-4) and other monomers include monomers a, b, . &Lt; / RTI &gt;

The (meth) acrylic copolymer (A) may be a random copolymer of the respective monomer components, or may be a block copolymer.

In the present invention, the (meth) acrylic copolymer (A) may be used singly or in combination of two or more kinds.

[(B) Crosslinking agent]

The pressure-sensitive adhesive composition for an optical member of the present invention contains a crosslinking agent (B) together with the (meth) acrylic copolymer (A) described above.

The crosslinking agent (B) is not particularly limited as long as it can cause a crosslinking reaction with the (meth) acrylic copolymer (A). Examples thereof include an isocyanate crosslinking agent, a metal chelate crosslinking agent and an epoxy crosslinking agent.

Specific examples of the isocyanate-based crosslinking agent include tolylene diisocyanate, chlorophenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenyl Isocyanate monomers such as methane diisocyanate; An isocyanate compound in which these isocyanate monomers are added to trimethylolpropane and the like; Isocyanurate compounds; Burette-type compounds; And urethane prepolymer type isocyanates which are further reacted with known polyether polyols, polyester polyols, acrylic polyols, polybutadiene polyols, polyisoprene polyols and the like.

Examples of the metal chelating crosslinking agent include isopropyl alcohol, acetylacetone, or acetoacetyl ethyl or the like in combination with a multivalent metal such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, And the like.

Specific examples thereof include aluminum isopropylate, diisopropoxybisacetylacetone titanate and aluminum triethylacetoacetate.

Specific examples of the epoxy cross-linking agent include ethylene glycol glycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,3-bis (N, N-diglycidyl) N, N, N ', N'-tetraglycidylaminophenylmethane, triglycidyldimethylsilane, N, N'-tetraglycidyl-m-xylylenediamine, Isocyanurate, mN, N-diglycidylaminophenyl glycidyl ether, N, N-diglycidyl toluidine and N, N-diglycidyl aniline.

The crosslinking agent (B) described above may be used alone or in combination of two or more.

Such a crosslinking agent (B) is contained in an amount of 0.01 to 3 parts by weight based on 100 parts by weight of the (meth) acrylic copolymer (A) in the pressure-sensitive adhesive composition for an optical member of the present invention.

By containing a certain amount of the cross-linking agent (B) in this manner, it is possible to achieve an appropriate degree of crosslinking and realize excellent tackiness, dimensional stability, light leakage preventing performance and durability under a humid environment. From such a viewpoint, the content of the crosslinking agent (B) is preferably 0.03 to 2.5 parts by weight based on 100 parts by weight of the (meth) acrylic copolymer (A).

[Other components]

The pressure-sensitive adhesive composition for an optical member of the present invention may further contain additives such as a silane coupling agent, an antistatic agent, an antioxidant, an ultraviolet absorber, a colorant, a pigment, a dye, a tackifier resin, a surface lubricant, a leveling agent, a softening agent, Other ingredients such as a photoinitiator, a polymerization inhibitor, a filler, organic particles, an inorganic particle or a plasticizer may be contained. The composition of the present invention may contain a solvent or other solvent used in the production of the (meth) acrylic copolymer (A). Hereinafter, the silane coupling agent and the antistatic agent will be described.

<Silane coupling agent>

Examples of the silane coupling agent include a polymerizable unsaturated group-containing silicon compound such as vinyltrimethoxysilane, vinyltriethoxysilane and methacryloxypropyltrimethoxysilane; Silicon compounds having an epoxy structure such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane; Amino group-containing silicon compounds such as 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropyltrimethoxysilane and N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane; And 3-chloropropyltrimethoxysilane; An oligomer type silane coupling agent, and the like.

Of these, use of a silane coupling agent having a functional group reactive with a functional group contained in the (meth) acrylic copolymer (A) is preferable because it is difficult to cause peeling in a moist heat environment.

The blending amount of the silane coupling agent in the pressure-sensitive adhesive composition for an optical member of the present invention is usually 0.01 to 0.5 parts by weight, preferably 0.05 to 0.3 parts by weight, per 100 parts by weight of the (meth) acrylic copolymer (A) to be.

<Antistatic agent>

The antistatic agent is used for lowering the surface resistance value of the pressure-sensitive adhesive composition for an optical member of the present invention. In the present invention, known antistatic agents can be used. These antistatic agents can be roughly classified into (i) surfactants, (ii) ionic compounds and (iii) conductive polymers.

(I) As the surfactant, the following surfactants may be used. Cationic surfactants having cationic groups such as quaternary ammonium salts, amide quaternary ammonium salts, pyridinium salts, and primary to tertiary amino groups;

Anionic surfactants having anionic groups such as sulfonic acid bases, sulfuric acid ester bases and phosphoric acid ester bases;

Amphoteric surfactants such as alkyl betaines, alkyl imidazolinium betaines, alkylamine oxides and amino acid sulfuric acid esters,

Nonionic surfactants such as glycerin fatty acid esters, sorbitan fatty acid esters, polyoxyethylene alkylamines, polyoxyethylene alkylamine fatty acid esters, N-hydroxyethyl-N-2-hydroxyalkylamines, and alkyldiethanolamides Surfactants.

As the surfactant, a reactive emulsifier having a polymerizable group may be used, and a polymer surfactant obtained by polymerizing the above-mentioned surfactant or a monomer component containing a reactive emulsifier may be used.

(Ii) The ionic compound is composed of a cationic part and an anionic part, and may be a solid phase or a liquid phase at room temperature (23 DEG C, 50% RH).

The cation unit may be either one of inorganic cation or organic cation, or both.

As the inorganic cation, alkali metal ions and alkaline earth metal ions are preferable, and Li ⁺ , Na ^+, and K ⁺ having excellent antistatic properties are more preferable.

Examples of the organic based cation include pyridinium cation, piperidinium cation, pyrrolidinium-based cation, pyrroline cation, pyrrole cation, imidazolium cation, tetrahydropyrimidinium cation, dihydro Pyrimidinium cation, pyrazolium cation, pyrazolinium cation, tetraalkylammonium cation, trialkylsulfonium cation, tetraalkylphosphonium cation, and derivatives thereof.

On the other hand, the anion constituting the ionic compound is not particularly limited as long as it can form an ionic compound by ionic bonding with the cation. Specific examples thereof include F ^- , Cl ^- , Br ^- , I ^- , AlCl ₄ ^- , Al ₂ Cl ₇ ^- , BF ₄ ^- , PF ₆ ^- , SCN ^- , ClO ₄ ^- , NO ₃ ^- , CH ₃ COO ^{- _{CF 3 COO -, CH 3 SO}} 3 -, CF 3 SO 3 -, (CF 3 SO 2) 2 N -, (F 2 SO 2) 2 N -, (CF 3 SO 2) 3 C -, AsF 6 - _{^{, SbF 6 -, NbF 6 -}} , TaF 6 -, F (HF) n -, (CN) 2 N -, C 4 F 9 SO 3 -, (C 2 F 5 SO 2) 2 N -, C 3 F ₇ COO ^- and (CF ₃ SO ₂ ) (CF ₃ CO) N ^- and the like. Of these, anion containing a fluorine atom is preferable since it gives an ionic compound having a low melting point, and (F ₂ SO ₂ ) ₂ N ^- and (CF ₃ SO ₂ ) ₂ N ^- are particularly preferable.

Examples of the ionic compound used as an antistatic agent in the present invention include lithium bis (trifluoromethanesulfonyl) imide, lithium bis (difluorosulfonyl) imide, lithium tris (trifluoromethanesulfonyl) Methane, potassium bis (trifluoromethanesulfonyl) imide, potassium bis (difluorosulfonyl) imide, 1-ethylpyridinium hexafluorophosphate, 1-butylpyridinium hexafluorophosphate, 1- Methylpyridinium hexafluorophosphate, 1-octyl-4-methylpyridinium hexafluorophosphate, 1-octyl-4-methylpyridinium bis (fluorosulfonyl) imide, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium bis (trifluoromethanesulfonyl) ethyl- ) Imide, 1-octylpyridinium fluorosulfonium imide, 1-octyl 3-methylpyridinium and trifluorosulfonium imide, and the like are preferable The.

(Iii) Examples of the conductive polymer include polythiophene, polyaniline, polypyrrole, and derivatives thereof.

The blending amount of the antistatic agent in the pressure-sensitive adhesive composition for an optical member of the present invention is usually 0.01 to 3 parts by weight, preferably 0.05 to 2.5 parts by weight, based on 100 parts by weight of the (meth) acrylic copolymer (A).

[Pressure sensitive adhesive composition for optical member]

The pressure-sensitive adhesive composition for an optical member of the present invention may contain the above-mentioned (meth) acrylic copolymer (A) and the crosslinking agent (B) as essential components, and optionally other components as described above.

In the (meth) acrylic copolymer (A), since the (meth) acrylic acid esters (a-2) and (a-3) are copolymerized in a specific ratio, excellent hard properties and optical compensation functions are compatible, In addition, since the (meth) acrylic acid ester (a-1) is also copolymerized, excellent dimensional stability is achieved by not only strengthening the hard properties but also introducing appropriate flexibility into the (meth) acrylic copolymer (A).

In addition, in the (meth) acrylic copolymer (A), the (meth) acrylic monomer (a-4) is also copolymerized and the cross-linking agent (B) Excellent dimensional stability and durability in a sticky and moist heat environment can be realized.

Since the composition of the present invention is excellent in dimensional stability and durability under a humid environment, it is very less deformed even in a humid environment, and the phenomenon of deteriorating the product value such as foaming is also unlikely to occur.

For example, when the microcref test is carried out under the conditions described below using the composition of the present invention, the ratio of the measured value at 60 캜 to the measured value at 23 캜 (measured at 60 캜 / 23 캜 measured Value) is usually from 1.05 to 2.00, and preferably from 1.05 to 1.95.

· Micro creep test

The pressure-sensitive adhesive composition for an optical member of the present invention is coated on a peeled polyester film and dried to produce a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having a thickness of 25 占 퐉.

This pressure sensitive adhesive sheet is bonded to a polarizing plate (a flat polarizing plate) having a layered structure of TAC (triacetylcellulose) -PVA (polyvinyl alcohol) -TAC so that the pressure sensitive adhesive layer is in contact with the polarizing plate to produce an adhesive process polarizing plate for evaluation.

The prepared pressure-sensitive adhesive polarizing plate for evaluation was cut into a width of 10 mm and a length of 100 mm. The peeled polyester film was peeled off so that the pressure-sensitive adhesive layer was brought into contact with the glass on the alkali- So as to be a conjugate area.

Thereafter, an autoclave process (50 DEG C, 5 atm) was applied to the adhesive process polarizing plate for evaluation combined with the above glass, and the sample was immediately stopped for 24 hours under an atmosphere of 23 DEG C / 50% RH to prepare a sample for microscopic creep test .

The sample set for test is set to a length of 15 mm of the fixing chuck portion in the chamber BOX of the micro creep measuring instrument, and the inside of the chamber BOX is heated to the measurement temperature (23 DEG C or 60 DEG C). The pressure-sensitive adhesive working polarizing plate for evaluation in the test sample was applied in parallel with the bonding surface between the polarizing plate and the glass, and further with a tensile load of 800 g and a tensile time of 1000 seconds, .

After the tensile test, the distance (mm) of deviation of the joining portion between the glass and the polarizing plate is measured to obtain the microscopic creep test result (measured value).

The measured value at 23 deg. C in the micro creep test is usually 0.05 to 1.00 mm, preferably 0.08 to 0.50 mm, more preferably 0.10 to 0.30 mm,

The measured value at 60 占 폚 in the micro creep test is preferably 0.15 to 1.00 mm, and more preferably 0.15 to 0.50 mm.

That is, the composition of the present invention is hard to cause deformation even in a humid environment, so that the dimensional stability is excellent, and the degree of deformation does not change much due to a change in temperature.

The measured values in these micro creep tests are mainly defined by the hard properties of the composition of the present invention, and the measurement values are also changed by adjusting these properties. (Meth) acrylic ester (a-2) in the (meth) acrylic copolymer (A) or to increase the copolymerization ratio of the (meth) acrylic monomer ) Or the amount of the cross-linking agent (B) is increased, the measured value tends to become smaller. The copolymerization ratio of the (meth) acrylic ester (a-2) in the (meth) acrylic copolymer (A) may be lowered or the copolymerization ratio of the (meth) acrylic monomer (a- When the amount of the cross-linking agent (B) used is made small, the above-mentioned measured value tends to become large.

As described above, since the deformation in the moist heat environment is very small, the composition of the present invention exhibits stress resistance when the optical member to which it is adhered exhibits deformation such as shrinkage, lifting, and deformation under a humid environment, .

As a result, light leakage caused by the deformation is also well prevented. Even if the prevention of light leakage is not complete, slight light leakage is also suppressed by the optical compensation function derived from the (meth) acrylic copolymer (A).

[Adhesive sheet]

When the pressure-sensitive adhesive composition for an optical member of the present invention is used as a pressure-sensitive adhesive, it is convenient and convenient to form a pressure-sensitive adhesive sheet by forming a pressure-sensitive adhesive layer on a base film.

The base film is preferably a release film in consideration of handling properties such as when the adhesive sheet is used in the production process of a flat panel display. Examples of the release film include polyester, polyolefin, polyether .

In the pressure-sensitive adhesive sheet of the present invention, for example, a coating liquid containing the pressure-sensitive adhesive composition for an optical member of the present invention is coated on a base film and dried to vaporize a solvent or the like contained in the coating liquid to form a pressure- . The thickness of the pressure-sensitive adhesive layer is not particularly limited, but is preferably in the range of 5 to 100 占 퐉, and more preferably in the range of 10 to 50 占 퐉. If the thickness of the pressure-sensitive adhesive layer is less than 5 mu m, a predetermined performance (wet heat durability) may not be exhibited. On the other hand, if the thickness exceeds 100 mu m, the pressure- There may be a case where it is lowered.

In the pressure-sensitive adhesive sheet of the present invention, the surface of the pressure-sensitive adhesive layer that is not in contact with the base film surface may be covered with a release film, and the release film may be peeled off during use.

[Optical member with pressure-sensitive adhesive layer]

By forming the pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition for optical members of the present invention on at least one surface of the optical member, the optical member with a pressure-sensitive adhesive layer having excellent light leakage prevention performance and durability even under a humid environment as described above can be obtained.

The optical member in the present invention is not particularly limited and may be an optical film preferably used for a flat panel display such as a polarizing plate, a retardation plate, an elliptically polarizing plate, an optical compensation film, a luminance enhancement film, an infrared / A film, an antireflection film for a front surface, a surface protective film, and a laminate thereof.

In particular, the polarizing plate, in particular, undergoes optical deformation or physical deformation due to the degree of deformation of the constituent layer under a humid environment, which causes birefringence. This birefringence becomes a serious problem because it causes light leakage. The composition of the present invention suppresses the deformation of the polarizing plate due to the hard property and is capable of suppressing the occurrence of optical deformation, that is, light leakage, and is also excellent in durability such as peeling suppression. In addition, it is preferable for the application of the polarizing plate to the glass substrate in that light leakage can be suppressed by the optical compensation function even if some optical deformation occurs.

Further, the composition of the present invention can be applied to a liquid crystal panel for a TV having a relatively large size in that deformation of a polarizing plate can be suppressed by a hard characteristic. And is particularly suitable for the application of the polarizing plate used in the VA mode liquid crystal panel to the glass substrate.

&Lt; Method for producing optical member with pressure-sensitive adhesive layer &gt;

The optical member with a pressure-sensitive adhesive layer is produced, for example, by the following methods (1) to (3).

(1) The coating liquid containing the pressure-sensitive adhesive composition for an optical member of the present invention is applied to the release layer of the release film by a known method (die coating method, knife coat method, etc.) A solvent or the like is vaporized to form a pressure-sensitive adhesive layer having a desired thickness, and the pressure-sensitive adhesive layer is bonded to the optical member.

(2) A coating liquid containing the pressure-sensitive adhesive composition for an optical member of the present invention is applied to an optical member by a known method (die coating method, knife coating method or the like), and a solvent or the like contained in the coating liquid is heat- Vaporized to form a pressure-sensitive adhesive layer having a desired thickness, and bonded to the release layer of the release film.

(3) The coating liquid containing the pressure-sensitive adhesive composition for an optical member of the present invention is applied to the release layer of the first release film by a known method (die coating method, knife coating method, etc.) Is vaporized to form a pressure-sensitive adhesive layer having a desired thickness, and the pressure-sensitive adhesive layer is laminated with the release layer of the second release film (usually, the release force is lower than that of the first release film) to produce a non-carrier pressure- . Thereafter, the second peeling film is peeled off and bonded to the optical member.

The pressure-sensitive adhesive composition for an optical member of the present invention can be cured for 3 to 7 days at room temperature (23 ° C, 50% RH), 2 to 5 days , And can be attached to a constituent layer of a flat panel display described later.

The thickness of the pressure-sensitive adhesive layer in the optical member with a pressure-sensitive adhesive layer to be obtained is not particularly limited, but is preferably in the range of 5 to 100 탆, more preferably in the range of 10 to 50 탆. If the thickness of the pressure-sensitive adhesive layer is less than 5 m, a predetermined performance (wet heat durability) may not be exhibited. On the other hand, when the thickness exceeds 100 m, the pressure- The processability may be lowered.

When the composition of the present invention is used in the production of FPD, a pressure-sensitive adhesive layer comprising the composition is formed as a component layer of the FPD. The pressure-sensitive adhesive layer contains a crosslinked product of the (meth) acrylic copolymer (A) having an optical compensation function, and the photoelastic coefficient of the pressure-sensitive adhesive layer is preferably -320 to 0 (x 10 ^-12 m 2 / N). The measurement method of the photoelastic coefficient is described in the section of [Examples].

[Flat Panel Display]

It is possible to manufacture a flat panel display using at least one optical member with a pressure-sensitive adhesive layer of the present invention, and the FPD thus produced is also included in the scope of the present invention.

Examples of the FPD include a liquid crystal display (LCD), a plasma display (PDP), and a field emission display (FED).

In general, an LCD is a liquid crystal display device in which a liquid crystal layer is sandwiched by a glass substrate having a transparent electrode, and an orientation film and a color filter are formed between the glass substrate and the liquid crystal layer, and on the surface opposite to the liquid crystal layer side of the glass substrate And a laminate structure in which a polarizing plate is formed.

PDPs generally have a structure in which a phosphor layer exists between opposing glass substrates and a multilayer structure in which various dielectric layers, electrodes, and other functional layers are formed on a surface of the glass substrate close to the phosphor layer.

The FED generally includes a glass substrate, an anode electrode (anode) formed on the substrate, a phosphor layer formed on the electrode, a space of a vacuum, and a cathode electrode (cathode) facing the phosphor layer with a space therebetween And a laminate structure of a glass substrate.

The optical member with a pressure-sensitive adhesive layer of the present invention constitutes a part of the constituent layers of these FPDs. Further, at least a part of the constituent layers of the FPD may be sequentially laminated using the adhesive sheet of the present invention.

Example

Hereinafter, the present invention will be described in detail by way of examples.

<Production Example of Acrylic Copolymers Used in Examples 1 to 13 and Comparative Examples 1 to 8>

(A-1) to (a-3) and an acrylic monomer (a-4) shown in Tables 1 to 3 shown below in Tables 1 to 3 were charged in a reaction apparatus equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen- (Parts by weight) shown in Table 1, and then ethyl acetate was injected at a compounding amount such that the monomer concentration became 50 wt%.

Subsequently, 0.1 part by weight of 2,2'-azobisisobutyronitrile was added to 100 parts by weight of the total of the acrylic ester (a-1) to (a-3) and the acrylic monomer (a-4) The mixture was stirred while replacing the air with nitrogen gas, and the temperature was raised to 60 DEG C, and the reaction was carried out at a pressure of 1 atm for 4 hours. After completion of the reaction, the obtained acrylic copolymer was diluted with ethyl acetate to obtain an acrylic copolymer solution.

&Lt; Preparation of pressure-sensitive adhesive polarizing plate for evaluation &

Using the acrylic copolymer solution obtained in Production Example, each component was added in the formulas shown in Tables 1 to 3 below to obtain a solution of the pressure-sensitive adhesive composition. The solution of the pressure-sensitive adhesive composition was coated on the surface of the peeled polyester film and dried to obtain a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having a thickness of 25 占 퐉. This adhesive sheet was attached to one side of a polarizing film having a layer constitution of TAC-PVA-TAC and aged for 7 days under conditions of darkness at 23 DEG C / 50% RH to obtain a pressure-sensitive adhesive polarizing plate for evaluation.

The evaluation of the micro creep, light leakage, lifting and foaming, cracking and peeling shown in the following Tables 1 to 3 was carried out on each of the adhesive processing polarizing plates for evaluation.

* The contents of the abbreviations in Tables 1 to 3 are as follows.

BA: n-butyl acrylate

t-BA: tertiary butyl acrylate

POA: phenoxyethyl acrylate

HEA: 2-hydroxyethyl acrylate

MA: methyl acrylate

CHA: cyclohexyl acrylate

IBOA: isobornyl acrylate

AA: Acrylic acid

TD: XDI isocyanate compound (TD-75: manufactured by Soken Chemical & Engineering Co., Ltd.)

L: TDI adduct type isocyanate compound (Colonate L: manufactured by Nippon Polyurethane Industry Co., Ltd.)

KBM-403: 3-glycidoxypropyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd.)

Antistatic agent: 1-octyl-4-methylpyridinium bis (fluorosulfonyl) imide

[Tg measurement]

The Tg of the homopolymers of the various acrylic monomers (a-1) to (a-3) shown in Tables 1 to 3 was measured as follows.

Various homopolymers shown in Table 4 below were prepared by solution polymerization to prepare test specimens.

The temperature of the test piece was raised at a rate of 10 ° C / minute in a range of -60 ° C to 180 ° C under an N ₂ atmosphere, and the temperature was measured with a DSC (differential scanning calorimeter DSC8230 manufactured by Rigaku Corporation) according to JIS K 7121 And the calorific value was measured.

[Mw, PDI measurement]

The polydispersity index (PDI = Mw / Mn) was determined by measuring the weight average molecular weight (Mw) and number average molecular weight (Mn) of the acrylic copolymer prepared in Examples and Comparative Examples according to the following GPC measurement conditions.

&Lt; GPC measurement condition &gt;

Measuring apparatus: HLC-8120GPC (manufactured by Tosoh Corporation)

GPC Column Composition: The following five columns (all manufactured by Toso Co., Ltd.)

(1) TSK-GEL HXL-H (Guard column)

(2) TSK-GEL G7000HXL

(3) TSK-GEL GMHXL

(4) TSK-GEL GMHXL

(5) TSK-GEL G2500HXL

Sample concentration: diluted with tetrahydrofuran to 1.0 mg / cm3

Mobile phase solvent: tetrahydrofuran

Flow rate: 1 ml / min

Column temperature: 40 DEG C

[Each evaluation method]

The various evaluations shown in Tables 1 to 3 were carried out according to the following methods.

<Smile Creep>

The pressure-sensitive adhesive polarizing plate for evaluation, which was cut into a width of 10 mm and a length of 100 mm and peeled off from the polyester film thus peeled off, was applied onto the alkali-treated glass so that the adhesive layer was in contact with the glass and a bonding area of 10 mm x 10 mm , And the mixture was autoclaved (50 ° C, 5 atm), and then quenched for 24 hours under a 23 ° C / 50% RH atmosphere. This was used as a specimen for micro creep test. A sample set for test was set at a length of 15 mm of the fixing chuck portion in the chamber BOX of the micro creep measuring instrument (TA-TX. PLUS manufactured by Eiko Kogyo Co., Ltd.).

After heating the inside of the chamber BOX to the measurement temperature and stopping for 40 minutes at the measurement temperature, the pressure-sensitive adhesive working polarizing plate for evaluation in the test sample was applied with a tensile load of 800 g and a tensile time of 1000 seconds, And also in the longitudinal direction of the polarizing plate. (Measured) by measuring the distance (mm) of the deviation between the glass and the polarizing plate after the stretching, to obtain the micro creep test results.

<Light leakage>

A pressure-sensitive adhesive process polarizing plate for evaluation, in which a peeled polyester film was peeled off, was laminated on a 19-inch VA type liquid crystal panel (manufactured by I &amp; DATA Corporation, type: LCD-A191EW) And the above-mentioned pressure-sensitive adhesive working polarizing plate for evaluation and the above-mentioned liquid crystal panel were cross-knit together, left for 240 hours in an atmosphere at 80 占 폚, and left for 2 hours in an atmosphere of 23 占 폚 / 50% RH.

Thereafter, the VA type liquid crystal panel in which the polarizing plate was stuck was connected to a PC in a dark room to make full-screen black display. The luminance (Lcenter) in the area of 1 cm in diameter in the vicinity of each corner and the luminance (La, Lb, Lc, Ld) in the area of 1 cm in diameter in the central part of the monitor, Was measured using a luminance meter (RISA-COLOR / CD8 manufactured by Highland Corporation), and the light leakage property (? L) was determined by the following formula. The smaller ΔL means less light leakage (from the backlight), and typically less than 2.0, it can be used as a liquid crystal display panel.

? L = (La + Lb + Lc + Ld) / 4-Lcenter

In the light leakage size, a portion where light leakage occurred visually in the full-screen black display state was confirmed, and the distance d from the corner of the light leakage occurrence portion was measured as shown in Fig. If the distance is 30 mm or less, it can be used as a liquid crystal display panel.

With respect to Comparative Examples 1 and 3 to 6, the display monitor was checked after being left in an atmosphere of 80 ° C for 240 hours. As a result, appearance defects due to the pressure-sensitive adhesive layer such as foaming and peeling occurred, and the measurement of the light leakage test was impossible.

<Heat and Heat Durability>

An adhesive process polarizing plate for peeling off the peeled polyester film was cut to a size of 15 inches (233 mm x 309 mm), a pressure-sensitive adhesive layer was brought into contact with the glass plate on one side of a 0.5 mm-thick non-alkali glass plate, Using a roll. After the application, the plate was pressurized with an autoclave (manufactured by Kurihara Seisakusho) under the conditions of 0.5 MPa and 50 캜 for 20 minutes to obtain a test plate.

The test plate thus obtained was allowed to stand under the condition of 60 占 폚 / 90% RH for 500 hours. After the completion of the test, the test plate was taken out of the test environment and allowed to stand still for 2 hours under an atmosphere of 23 DEG C / 50% RH. Then, foaming, peeling and cracks in the pressure-sensitive adhesive layer were visually observed and evaluated according to the following evaluation criteria.

Foam - Size

○: No foaming is observed at all

?: The diameter of the foaming is not more than 1 mm

X: diameter of foaming is larger than 1 mm

Foam - Emission

○: No foaming is observed at all

: The number of foams was 10 or less

X: Number of foams is more than 10

Crack · Peeling - Size

○: No peeling or peeling is observed at all

?: Less than 5% of the total area (100%) of the joining portion in the test plate

X: 5% or more with respect to the entire joining portion (100%) of the test plate in the exciting / peeling area

Cracking / peeling - position

○: There is no defect (peeling, peeling).

?: There is a defect only at a position less than 0.5 mm from the end

X: There is a defect at a position of 0.5 mm or more from the end.

The term &quot; end portion &quot; in the evaluation of the crack and peeling-position refers to the intersection of the shortest waterline and the side of the test plate when the waterline is lowered to each side of the test plate from the position where cracking and peeling occurred.

The test plates for Comparative Examples 5 and 6 were left for 500 hours under the conditions of 60 ° C / 90% RH. As a result, many peeling and foaming originated from the pressure-sensitive adhesive layer occurred, and evaluation of cracking and peeling was impossible .

&Lt; Measurement of photoelastic coefficient &

A pressure-sensitive adhesive test piece having a thickness of 15 mm x 50 mm x 1 mm was prepared as follows and used as a measurement sample.

A crosslinking agent, a silane coupling agent and an antistatic agent were added to the acrylic copolymer solution obtained in Production Example in the proportions shown in Tables 1 to 3 to prepare a pressure-sensitive adhesive composition solution. This pressure-sensitive adhesive composition solution was coated and dried on the peeled PET film so that the thickness after drying was 1 mm. After drying, the sample was cut into 15 mm x 50 mm to obtain a pressure-sensitive adhesive test piece (12), which was used as a sample for measurement.

The measurement sample was set in a measuring apparatus (Spectroscopic Ellipsometer M-220 manufactured by Nippon Denshoku Co., Ltd.), and measurement was carried out at 23 캜.

2, the relationship (* 1) of the phase difference of the wavelength-transmitted light for each stress was measured by controlling the stress generated when the specimen was tensioned in the X direction in the range of 0 to 0.15 N. In Fig. (* 1) was plotted against the phase difference of the transmitted light at a wavelength of 600 nm with respect to the phase difference-stress, and the slope thereof was obtained. Further, the photoelastic coefficient was determined from the relationship of the slope = (-1) x the photoelastic coefficient (10 ^-12 m2 / N).

12: Adhesive test piece
14: Sample fixing jig
16: Light source
18: slit
20: analyzer

Claims (14)

(Meth) acrylic copolymers obtained by copolymerizing the following (a-1) to (a-4) at the following ratios:
(meth) acrylate having a glass transition temperature of -40 占 폚 or less and no aromatic ring (a-1) 40 to 94.9% by weight,
(meth) acrylate having a glass transition temperature of 0 占 폚 or higher and having no aromatic ring in the homopolymer (a-2) is 0.1 to 50% by weight,
0.1 to 25% by weight of a (meth) acrylic acid ester having an aromatic ring (a-3)
(a-4) 0.1 to 6% by weight of a (meth) acrylic monomer having two or more polar functional groups and / or two or more different (meth) acrylic monomers having one polar functional group,
(Provided that the sum of (a-2) and (a-3) is 5 to 59.9 wt%
The polar functional group is selected from a carboxyl group, a hydroxyl group, an amino group, an amide group and an epoxy group,
(a-1) to (a-4) is 100% by weight)
(B): 0.01 to 3 parts by weight of a crosslinking agent based on 100 parts by weight of the (meth) acrylic copolymer (A). The method according to claim 1,
Wherein the copolymerization ratio of the (meth) acrylic acid ester (a-2) is 10 to 40% by weight. 3. The method according to claim 1 or 2,
Wherein the (meth) acrylic acid ester (a-2) is at least one compound selected from the group consisting of methyl (meth) acrylate, i-butyl methacrylate, t- butyl (meth) acrylate, cyclohexyl (meth) acrylate and isobornyl Wherein the pressure-sensitive adhesive layer is at least one member selected from the group consisting of a pressure-sensitive adhesive and a pressure-sensitive adhesive. 3. The method according to claim 1 or 2,
Wherein the (meth) acrylic acid ester (a-2) is t-butyl (meth) acrylate. 5. The method according to any one of claims 1 to 4,
Wherein the copolymerization ratio of the (meth) acrylic acid ester (a-1) is 50 to 90% by weight. 6. The method according to any one of claims 1 to 5,
Wherein the (meth) acrylic acid ester (a-1) is at least one selected from the group consisting of n-butyl acrylate, n-pentyl acrylate, isopentyl acrylate, hexyl acrylate, heptyl acrylate, isoamyl acrylate, (Meth) acrylate, n-decyl methacrylate, n-dodecyl methacrylate, n-tridecyl (meth) acrylate, n-octyl acrylate, isooctyl acrylate, n-nonyl acrylate, isononyl acrylate, (Meth) acrylate, methoxyethyl acrylate, methoxypolyethylene glycol acrylate, and ethoxyethoxyethyl acrylate. The pressure-sensitive adhesive composition for optical members according to claim 1, 7. The method according to any one of claims 1 to 6,
(Meth) acrylate ester (a-3) is at least one selected from the group consisting of benzyl (meth) acrylate, phenoxyethyl (meth) acrylate ester represented by the following general formula (1) Sensitive adhesive composition for an optical member:
(3)

(In the formula (1), R ₀ is hydrogen or a methyl group, R ₁ is a group represented by (CH ₂ CH ₂ O) _n (n is an integer of 1 to 20), m is an integer of 1 to 5 , R ₂ is hydrogen, an alkyl group having 1 to 9 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an aralkyl group having 7 to 11 carbon atoms. When m is 2 or more, the plurality of R _{2 s} present may be the same or different. 8. The method according to any one of claims 1 to 7,
Wherein the copolymerization ratio of the (meth) acrylic monomer (a-4) is 1 to 6% by weight. 9. The method according to any one of claims 1 to 8,
Sensitive adhesive composition for an optical member, wherein a ratio of a measured value at 60 占 폚 to a measured value at 23 占 폚 is 1.05 to 2.00 when the following micro creep test is performed on the pressure-sensitive adhesive composition for optical member:
The pressure-sensitive adhesive composition for an optical member was coated on a peeled polyester film and dried to prepare a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having a thickness of 25 占 퐉;
The pressure-sensitive adhesive sheet was bonded to a polarizing plate having a TAC (triacetyl cellulose) -PVA (polyvinyl alcohol) -TAC structure so that the pressure-sensitive adhesive layer was in contact with the polarizing plate to produce an adhesive working polarizing plate for evaluation;
The pressure-sensitive adhesive polarizing plate for evaluation was cut into a width of 10 mm and a length of 100 mm, and the peeled polyester film was peeled off so that the pressure-sensitive adhesive layer came into contact with the glass, To give a bonding area, thereby obtaining a polarizing plate test piece for an evaluation adhesive process;
The pressure-sensitive adhesive polarizing plate test piece for evaluation was subjected to an autoclave treatment (50 DEG C, 5 atm) and quiescently stopped at 23 DEG C / 50% RH for 24 hours;
Next, the test piece was set in the chamber BOX of the micro creep measuring instrument at a length of 15 mm of the fixing portion;
After heating the inside of the chamber BOX to the measurement temperature and stopping at the measurement temperature for 40 minutes, the polarizing plate for evaluation and the polarizing plate for evaluation in the test piece were placed at a tensile load of 800 g and a tensile time of 1000 seconds Stretching in parallel with the adhesive surface and in the longitudinal direction of the polarizing plate;
The distance (mm) of the deviation of the fusion of the glass and the polarizing plate in the test piece is measured. 10. The method according to any one of claims 1 to 9,
And further contains 0.01 to 0.5 parts by weight of a silane coupling agent based on 100 parts by weight of the (meth) acrylic copolymer (A). 11. The method according to any one of claims 1 to 10,
Wherein the antistatic agent is contained in an amount of 0.01 to 3 parts by weight based on 100 parts by weight of the (meth) acrylic copolymer (A). A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer formed on a base film and containing the pressure-sensitive adhesive composition for an optical member according to any one of claims 1 to 11. An optical member with a pressure-sensitive adhesive layer provided with a pressure-sensitive adhesive layer on at least one side of an optical member, wherein the pressure-sensitive adhesive layer comprises the pressure-sensitive adhesive composition for optical member according to any one of claims 1 to 11 absence. A flat panel display comprising the optical member with a pressure-sensitive adhesive layer according to claim 13.

Images