KR101314403B1 - Adhesive composition - Google Patents

Abstract

This invention aims at the development of the technology which can simplify the laminated constitution of the front plate for PDP panels in which various functional films were laminated | stacked, and can provide the said low cost front plate, In the solution means, As a resin component It is an adhesive composition containing the (meth) acrylic acid ester type copolymer which has a crosslinkable functional group other than a carboxyl group, and contains 1 or more types of organic near-infrared absorbing pigment.

Description

[0001] ADHESIVE COMPOSITION [0002]

The present invention provides a pressure-sensitive adhesive composition, more specifically, a pressure-sensitive adhesive composition having a near-infrared absorptive performance excellent in durability and used in a front panel for plasma display panels in which various functional films are laminated, thereby simplifying the layer structure of the front panel. It is about.

A plasma display (PDP) is a device that displays an image by exciting molecules of xenon gas sealed by plasma discharge between electrodes, exciting fluorescent materials with generated ultraviolet rays, and emitting light in the visible region. In this PDP, since light emission uses plasma discharge, unnecessary electromagnetic waves of about 30 to 130 MHz are leaked to the outside, so that electromagnetic waves do not adversely affect other equipment (for example, an information processing apparatus). It is required to suppress the maximum force.

In the PDP, it is known to emit near infrared rays. This near-infrared light acts on surrounding electronic devices, such as a cordless phone and a video deck using a near-infrared remote control device, and may interfere with normal operation, and it is required to cut off this near-infrared light as much as possible.

In addition, in the PDP, since the display surface is flat, when external light flows in, light reflected in a wide range enters the eye at the same time, and the screen becomes difficult to see, and it is necessary to prevent reflection of external light. It is also important to transmit the light emission of the PDP with a predetermined transmittance to perform good screen display and to correct the color tone of the luminescent color.

In the PDP, in response to these demands, a front plate having at least three functional films of (1) electromagnetic wave blocking film, (2) near infrared absorbing film, and (3) antireflection film on the display screen is reflected. The treatment which arrange | positions so that a prevention film may become the surface (observer side) is calculated | required (for example, refer patent document 1). In this case, at least three functional films must be produced separately and glued together to avoid costly eating.

On the other hand, in recent years, in terms of cost reduction, the antireflection film on the outermost surface is formed by forming a near-infrared absorbing layer on the surface opposite to the antireflection layer of the substrate, thereby preventing antireflection with one film. Functional films have been developed that combine performance and near infrared absorption. When manufacturing such a functional film, there are two methods, (1) formation of a near infrared absorbing layer on the back side of the antireflection film, and (2) formation of an antireflection layer on the back side of the near infrared absorbing film. Since loss of film occurs, the effect of cost reduction is small.

Moreover, when forming a near-infrared absorbing layer, although the wet process of apply | coating the coating agent containing a near-infrared absorber, or the dry process which forms the thin film layer of a metal type near-infrared absorber by vacuum deposition or sputtering is used, all operation is cumbersome.

On the other hand, coloring for electronic display in which the adhesive layer containing the (meth) acrylic-type resin which contains at least 1 sort (s) chosen from a neon cut pigment | dye, a xenon cut pigment | dye, and a near-infrared cut pigment | dye, and carbon black as an essential component to a transparent film is formed. An adhesive adhesion film is disclosed (for example, refer patent document 2). In this technique, by containing carbon black, the carbon black adsorbs and stabilizes the dye molecules, thereby improving the durability (heat resistance and moisture resistance) of the dye.

However, the addition of carbon black causes a problem that the transmittance of visible light is lowered and the haze value is increased, so that the optical properties of the resulting electronic display film are lowered.

[Patent Document 1]

Japanese Patent Application Laid-Open No. 11-126024

[Patent Document 2]

Japanese Patent Application Laid-Open No. 2003-82302

Under the circumstances, the present invention aims to simplify the layer structure of a front plate for a PDP panel in which various functional films are laminated, and to develop a technology capable of providing the low cost front plate.

MEANS TO SOLVE THE PROBLEM As a result of repeated research in order to achieve the said objective, at least one of each adhesive layer used for the front plate for PDP panels contains a near-infrared absorber, and also optical characteristics, such as visible light transmittance and a haze value, are included. It was noted that the near-infrared absorbing film or the near-infrared absorbing layer can be removed from the front plate for the PDP panel if the near-infrared absorptive performance with excellent durability can be imparted to the pressure-sensitive adhesive layer without causing deterioration.

Based on this idea, as a result of further research, in the adhesive composition which comprises an adhesive layer, the (meth) acrylic acid ester type copolymer which has a crosslinkable functional group other than a carboxyl group is used as a resin component, It was found that the object can be achieved by selecting and containing an organic near infrared absorbing dye to pass the endurance test under the conditions.

This invention is completed based on such knowledge.

That is, the present invention,

(1) A pressure-sensitive adhesive composition comprising, as a resin component, a (meth) acrylic acid ester copolymer having a crosslinkable functional group other than a carboxyl group, and at least one organic near-infrared absorbing pigment.

(2) the pressure-sensitive adhesive composition according to the above (1), wherein the organic near infrared absorbing dye is a phthalocyanine-based dye;

(3) The pressure-sensitive adhesive composition according to the above (2), wherein the content of the phthalocyanine-based dye is 0.1 to 5 parts by weight based on 100 parts by weight of the (meth) acrylic acid ester copolymer.

(4) It provides the adhesive composition in any one of said (1)-(3) used for the front plate attached to a plasma display.

<Embodiment of the Invention>

The adhesive composition of this invention contains a (meth) acrylic acid ester type copolymer which has a crosslinkable functional group other than a carboxyl group as a resin component, and contains at least 1 type of organic near-infrared absorbing pigment.

In addition, in this invention, a (meth) acrylic acid ester refers to both an acrylic acid ester and methacrylic acid ester. The same is true of other similar expressions.

There is no restriction | limiting in particular as a (meth) acrylic acid ester type copolymer which has a crosslinkable functional group other than the said carboxyl group, Among the (meth) acrylic acid ester type copolymers conventionally used as a resin component of an adhesive, it selects suitably and uses it suitably. Can be.

As a (meth) acrylic acid ester type copolymer which has such a crosslinking point, the C1-C20 (meth) acrylic acid ester of the alkyl group of an ester part, the monomer which has crosslinkable functional groups other than a carboxyl group, and is used by desire Copolymers with other monomers are preferable.

Here, as an example of the C1-C20 (meth) acrylic acid ester of the alkyl group of an ester part, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and pentyl (meth) acrylate Hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, dodecyl (meth) acrylate, myristyl (meth) acrylate, Palmityl (meth) acrylate, stearyl (meth) acrylate, etc. are mentioned. These may be used alone or in combination of two or more.

On the other hand, as an example of the monomer which has a crosslinkable functional group other than a carboxyl group, (meth) acrylic-acid 2-hydroxyethyl, (meth) acrylic-acid 2-hydroxypropyl, (meth) acrylic-acid 3-hydroxypropyl, (meth) acrylic acid 2-hydroxy (Meth) acrylic-acid hydroxyalkyl esters, such as hydroxybutyl, (meth) acrylic acid 3-hydroxybutyl, and (meth) acrylic acid 4-hydroxybutyl; Acrylamides such as acrylamide, methacrylamide, N-methyl acrylamide, N-methyl methacrylamide, N-methylol acrylamide and N-methylol methacrylamide; (Meth) acrylic-acid monoalkyl aminoalkyl, such as (meth) acrylic-acid monomethyl aminoethyl, (meth) acrylic-acid monoethylaminoethyl, (meth) acrylic-acid monomethylaminopropyl, (meth) acrylic-acid monoethylaminopropyl, etc. are mentioned. . These monomers may be used alone or in combination of two or more.

Moreover, as an example of another monomer used as desired, Vinyl ester, such as vinyl acetate and a vinyl propionate; Olefins such as ethylene, propylene and isobutylene; Halogenated olefins such as vinyl chloride and vinylidene chloride; Styrene-based monomers such as styrene and? -Methylstyrene; Diene monomers such as butadiene, isoprene and chloroprene; Nitrile monomers such as acrylonitrile and methacrylonitrile; N, N- dialkyl substituted acrylamides, such as N, N- dimethyl acrylamide and N, N- dimethyl methacrylamide, etc. are mentioned. These may be used alone or in combination of two or more.

In the adhesive composition of this invention, the crosslinkable functional group in the said (meth) acrylic-ester type copolymer is functional groups other than a carboxyl group. When a carboxyl group exists in the said (meth) acrylic-ester type copolymer, durability of organic near-infrared absorbing pigment will fall easily (especially in case of a cationic pigment | dye, durability will be remarkably damaged). Although content of the crosslinkable functional group containing monomeric unit in the said (meth) acrylic acid ester-type copolymer depends on the kind, Usually, about 0.1-20 weight%, Preferably it is 1-10 weight%.

In the adhesive composition of this invention, the (meth) acrylic acid ester type copolymer does not have a restriction | limiting in particular about the copolymerization form, Any of a random, a block, and a graft copolymer may be sufficient. Moreover, as molecular weight, it is preferable to exist in the range of 300,000-2,500,000 by weight average molecular weight. If the weight average molecular weight is less than 300,000, the adhesion to the adherend and the adhesion durability may be insufficient. If the weight average molecular weight exceeds 2.5 million, the coating suitability may deteriorate. In consideration of adhesiveness, adhesion durability and coating suitability, the weight average molecular weight is preferably 300,000 to 2 million, particularly preferably 500,000 to 1.8 million.

In addition, the said weight average molecular weight is the value of polystyrene conversion measured by the gel permeation chromatography (GPC) method.

In this invention, this (meth) acrylic acid ester type copolymer may be used individually by 1 type, and may be used in combination of 2 or more type. If desired, the (meth) acrylic acid ester copolymer of high molecular weight and a (meth) acrylic acid ester homopolymer or copolymer having a low molecular weight, for example, a weight average molecular weight of 100,000 or less may be used in combination. .

Examples of the organic near-infrared absorbing pigment used in the pressure-sensitive adhesive composition of the present invention include a cyanine compound, a squarylium compound, a thiol nickel complex salt compound, a naphthalocyanine compound, a phthalocyanine compound, a triaryl methane compound, Naphthoquinone compound, anthraquinone compound, and further N, N, N ', N'-tetrakis (p-di-n-butylaminophenyl) -p-benzoquinone-bis (perchlorate of immonium), N, N, N ', N'-tetrakis (p-di-n-butylaminophenyl) -perchlorate of p-phenylenedinium, chlorine salt of phenylenedinium, hexafluoroantimony of phenylenedinium Amino compounds, such as acid salts, fluoroborate salts of phenylenediamine, fluoride salts of phenylenedium, perchlorate salts of phenylenedium, copper compounds and bisthiourea compounds, phosphorus compounds, copper compounds, phosphate ester compounds and copper Obtained by reaction with a compound Phosphoric acid ester copper compound etc. which are mentioned are mentioned.

In this invention, 1 or more types are selected suitably from the said organic type near-infrared absorption pigment | dye so that the adhesive composition obtained may pass by the endurance test mentioned later.

Among the organic near-infrared absorbing dyes, thiol nickel complex dyes (Japanese Patent Laid-Open No. 9-230134, etc.) and phthalocyanine-based dyes are preferable, and in particular, fluorine-containing phthalocyanine disclosed in Japanese Patent Laid-Open No. 2000-26748. The compound is very suitable because of its high visible light transmittance and excellent properties such as heat resistance, light resistance and weather resistance among organic near infrared absorbers.

As the fluorine-containing phthalocyanine compound, for example, EXCOLOR IR-10, EXCOL IR-12, EXCOL IR-14, TX-EX-906B, TX-EX-910B [All, Inc.] Nippon SHOKUBAI CO., LTD. Product, brand name], etc. are available as a commercial item.

When the said phthalocyanine pigment | dye is used as an organic near-infrared absorbing dye, the content in an adhesive composition is usually 100 weight part with respect to said (meth) acrylic-ester type copolymer in view of the balance of near-infrared absorption effect and economical efficiency. 0.1-5 weight part, Preferably it is 0.5-3 weight part, More preferably, it is 1-2.5 weight part.

In the adhesive composition of this invention, as an near-infrared absorber, an inorganic near-infrared absorber can be suitably used together with the said organic near-infrared absorption pigment as needed in the range which does not impair performance, optical characteristics, etc. as an adhesive.

Examples of the inorganic near infrared absorber include tungsten oxide compounds, titanium oxide, zirconium oxide, tantalum oxide, niobium oxide, zinc oxide, indium oxide, tin-doped indium oxide (ITO), tin oxide, and antimony-doped tin oxide. (ATO), cesium oxide, zinc sulfide, etc. are mentioned. These may be used 1 type or may be used in combination of 2 or more type.

In the adhesive composition of this invention, a crosslinking agent can be used. There is no restriction | limiting in particular as this crosslinking agent, Arbitrary thing can be suitably selected from a conventionally used as a crosslinking agent in acrylic adhesive. Examples of such crosslinking agents include polyisocyanate compounds, epoxy resins, melamine resins, urea resins, dialdehydes, methylol polymers, and the like. In the present invention, polyisocyanate compounds are preferably used.

Here, examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate. Aliphatic polyisocyanates, such as these, and adducts which are reactants with low molecular weight active hydrogen-containing compounds, such as those of a droplet, isocyanurate, and ethylene glycol, propylene glycol, neopentyl glycol, trimethylol propane, and castor oil, etc. Etc. can be mentioned.

In this invention, this crosslinking agent may be used individually by 1 type, and may be used in combination of 2 or more type. Moreover, although the usage-amount is based also on the kind of crosslinking agent, it is 0.001-50 weight part normally with respect to 100 weight part of said (meth) acrylic-ester type copolymers, Preferably it is selected in the range of 0.01-10 weight part.

In the pressure-sensitive adhesive composition of the present invention, as long as the object of the present invention is not impaired, various known additives conventionally used in the pressure-sensitive adhesive composition, for example, plasticizers, silane coupling agents, antioxidants, ultraviolet absorbers and the like, The dye may be added a dye or a pigment for correcting the color tone of the display device.

In particular, when the silane coupling agent is added to the pressure-sensitive adhesive composition among the various additives, the adhesion to the glass plate under moist heat conditions is improved, and lifting or peeling hardly occurs. As this silane coupling agent, an organosilicon compound having at least one alkoxysilyl group in a molecule is very suitable for compatibility with the pressure-sensitive adhesive component and having a light transmissive property, for example, a substantially transparent one. As such a silane coupling agent, a vinyl triethoxysilane, a vinyl tris (2-methoxyethoxy) silane, 3-methacryloxy propyl trimethoxysilane, (gamma)-glycidoxy propyl trimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, etc. are mentioned, The addition amount is an adhesive composition. The range of 0.001-10 weight part is preferable with respect to 100 weight part of solid content of, and the range of 0.005-5 weight part is especially preferable.

In the adhesive composition of this invention, when the durability test of near-infrared absorptivity is performed for 1000 hours with respect to the adhesive layer with a thickness of 25 micrometers by the method mentioned later, wavelength 850 nm, 900 nm, and before and after a test for 1000 hours, The difference in transmittance at 1000 nm is usually 5% or less in all cases. If the difference in the transmittance is 5% or less (normally, the transmittance after the test is higher than before the test), even if exposed for a long time under high temperature conditions, the deterioration of the near-infrared absorption performance is small, and the durability is excellent and practical. The difference in the transmittance is preferably 4.5% or less, and more preferably 2% or less.

In addition, the transmittance in the entire region of the wavelength of 850 to 1000 nm before the test is usually 30% or less. When the said transmittance | permeability is 30% or less, when the adhesive composition of this invention is applied to any one of each adhesive layer in the front plate for PDP panels, the peripheral electronic device by the near-infrared radiation which generate | occur | produces from the said PDP (for example, Malfunctions of cordless phones, video decks using near-infrared remote controls, etc. can be suppressed. The transmittance is preferably 20% or less.

In addition, the luminous average transmittance based on JIS Z 8701-1999 before and after the said test is 45% or more normally, Preferably it is 50% or more, and the difference of the luminous average transmittance before and after a test is 5% or less normally, Preferably it is 4% or less, More preferably, it is 2% or less. That is, even if the adhesive composition of this invention is applied to any one of each adhesive layer in the front plate for PDP panels, the visibility of the display screen and its durability are favorable.

Thus, the adhesive composition of this invention is excellent in near-infrared absorption performance and its durability, and also the performance (transparency, adhesive force, holding force) as an adhesive used for an optical member is also favorable. Therefore, it is suitably applied to each adhesive layer in the front plate for PDP panels. In this case, you may apply to any one of the said adhesive layers, and may apply to 2 or more types of adhesive layers.

By applying the adhesive composition of this invention to the said adhesive layer, the near-infrared absorption film or near-infrared absorption layer which is one of the laminated constitutions of the conventional front plate for PDP panels can be eliminated, and simplification of laminated constitution becomes possible.

When forming an adhesive layer in a to-be-adhered body using the adhesive composition of this invention, the thickness is 5-150 micrometers normally, Preferably it is 10-90 micrometers. Moreover, a peeling film can be formed on this adhesive layer as needed. As this peeling film, what apply | coated the peeling agent, such as a silicone resin, to paper and various plastic films, such as glassine paper, a coated paper, and laminated paper, etc. are mentioned, for example. Although there is no restriction | limiting in particular about the thickness of this peeling film, Usually, it is about 20-150 micrometers.

<Examples>

Next, although an Example demonstrates this invention in detail, this invention is not limited at all by these examples.

In addition, durability was evaluated by the following method about the adhesive composition obtained by each example.

<Evaluation of Durability>

On the 100-micrometer-thick polyethylene terephthalate film (Toyo Boseki company make, a brand name "Cosmoshine A4100"), an adhesive composition is apply | coated so that thickness after drying may be 25 micrometers, and an adhesive layer is formed. Next, after bonding to a 38 μm-thick polyethylene terephthalate film (peel film) (manufactured by Lintec, trade name "PET38PS"), the film was cut into a size of 50 mm x 50 mm and then peeled off. Is peeled off, and it adhere | attaches with the glass plate of thickness 1.1mm, and prepare a sample. This sample is subjected to the following test.

First, using an ultraviolet / visible spectrophotometer ("UV-3100" manufactured by Shimadzu Corporation), the luminous mean transmittance Y value was determined according to JIS Z 8701-1999, and the wavelength was measured at wavelengths of 850 nm, 900 nm, and 1000 nm. Each transmittance T in is measured. Subsequently, the samples were left for 1000 hours under the conditions of 80 ° C. and 60 ° C. and 90% relative humidity (RH), and the luring average transmittance Y value was determined in the same manner as above, and the wavelengths of 850 nm, 900 nm and 1000 nm were obtained. Each transmittance T in is measured, and the difference of the luminous average transmittance Y value before and behind a test, and the difference of each transmittance T are computed. The smaller these differences, the better the durability.

Example 1

Butyl acrylate, ethyl acrylate, and 2-hydroxyethyl acrylate were used in a weight ratio of 77: 15: 8, and polymerization was carried out according to a conventional method to prepare an acrylate ester copolymer (weight average molecular weight: 800,000). .

Next, 4 weight part (solid content) of an isocyanate type crosslinking agent (Nippon Polyurethane company make, brand name "colonate L") was added with respect to 100 weight part (solid content) of the said acrylic acid ester copolymer. Next, a phthalocyanine-based pigment is used as an organic near-infrared absorbing dye so that the light-transmitting average transmittance Y value of the obtained pressure-sensitive adhesive composition is 45% or more, and the transmittance T at wavelengths of 850 nm, 900 nm and 1000 nm is 15% or less, respectively. "EX Color IR-12", "EX Color IR-14", "TX-EX-906B", "TX-EX-910B" (all Nippon Shokubai Co., Ltd.), 0.30 part by weight, 0.23 part by weight, respectively , 0.14 part by weight and 0.90 part by weight (all solids) were added to methyl ethyl ketone, and added as a diluent solution to prepare a pressure-sensitive adhesive composition, and durability was evaluated. The results are shown in Table 1.

Example 2

Using butyl acrylate and 2-hydroxyethyl acrylate in a weight ratio of 92: 8, polymerization was carried out according to a conventional method to prepare an acrylate ester copolymer (weight average molecular weight of 600,000).

Hereinafter, it carried out similarly to Example 1, the adhesive composition was prepared, and durability was evaluated. The results are shown in Table 1.

Comparative Example 1

Using butyl acrylate, ethyl acrylate and acrylic acid in a weight ratio of 75: 20: 5, polymerization was carried out according to a conventional method to prepare an acrylate ester copolymer (weight average molecular weight: 800,000).

Hereinafter, the adhesive composition was prepared like Example 1, and durability was evaluated. The results are shown in Table 1.

Endurance Test
Condition Before the test After the test Y level
T Y level
T 850 nm 900 nm 1000 nm 850 nm 900 nm 1000 nm Example 1  80 ℃ 50.5 10.3 8.9 13.4 51.7 11.1 10.0 14.3  60 ℃, 90% RH 50.5 10.3 8.9 13.4 51.2 10.4 9.2 13.7 Example 2  80 ℃ 52.8 12.4 11.0 14.0 54.6 14.2 12.7 15.4  60 ℃, 90% RH 52.8 12.4 11.0 14.0 53.7 12.8 11.5 14.4 Comparative Example 1  80 ℃ 52.1 12.4 11.0 14.0 58.5 24.7 19.0 20.8  60 ℃, 90% RH 52.1 12.4 11.0 14.0 53.9 12.8 11.3 14.3

Endurance Test
Condition Change amount (after test-before test)
Judgment Y level T 850 nm 900 nm 1000 nm Example 1  80 ℃ 1.2 0.8 1.1 0.9 ○  60 ℃, 90% RH 0.7 0.1 0.3 0.3 ○ Example 2  80 ℃ 1.8 1.8 1.7 1.4 ○  60 ℃, 90% RH 0.9 0.4 0.5 0.4 ○ Comparative Example 1  80 ℃ 6.4 12.3 8.0 6.8 ×  60 ℃, 90% RH 1.8 0.4 0.3 0.3 ○

Judgment; (Circle): The change amount of Y value and the change amount of each T of 850 nm, 900 nm, and 1000 nm are all

          5% less than

      X: in the change amount of Y value and the change amount of each T of 850 nm, 900 nm, and 1000 nm

          Which one is over 5%

As can be seen from Table 1, the pressure-sensitive adhesive composition (Examples 1 and 2) of the present invention is excellent in durability as the amount of change in Y value and T is all less than 5%. In contrast, in the pressure-sensitive adhesive composition of Comparative Example 1, the amount of change in Y value in the durability test at 80 ° C. and 1000 hours exceeded 5%, and the amount of change in transmittance T at wavelengths of 850 nm, 900 nm, and 1000 nm was also 5. It is exceeding% and is inferior in durability.

Industrial availability

The adhesive composition of this invention has the near-infrared absorptivity excellent in durability, and can use for the front plate for PDP panels in which various functional films were laminated | stacked, and can simplify the layer structure of the said front plate.

ADVANTAGE OF THE INVENTION According to this invention, the adhesive composition which has the near-infrared absorption performance excellent in durability, and is used for the front plate for PDP panels in which various functional films were laminated | stacked can provide the adhesive composition which can simplify the laminated constitution of the said front plate.

Claims (6)

As the resin component, (meth) acrylic ester and (meth) acrylic acid 2-hydroxyethyl, (meth) acrylic acid 2-hydroxypropyl, (meth) acrylic acid 3-hydroxypropyl, (meth) acrylic acid 2-hydroxybutyl, (Meth) acrylic acid ester type copolymer which has crosslinkable functional groups other than the carboxyl group which copolymerized (meth) acrylic-acid hydroxyalkyl ester which is (meth) acrylic-acid 3-hydroxybutyl or (meth) acrylic acid 4-hydroxybutyl, 1 to 2.5 parts by weight of the polyisocyanate compound and the organic near-infrared absorbing dye with respect to 100 parts by weight of one or more fluorine-containing phthalocyanine-based pigments (meth) acrylic acid ester copolymer having a crosslinkable functional group other than the carboxyl group. As a composition to In the evaluation test for durability, first, the luminous mean transmittance Y value of the composition was determined based on JIS Z 8701-1999, and each transmittance T of the composition at wavelengths of 850 nm, 900 nm, and 1000 nm was measured, respectively. The composition is obtained by determining the luminous mean transmittance Y value of the composition after being left to stand for 1000 hours at 80 ° C, and measuring the transmittances T at wavelengths of 850 nm, 900 nm and 1000 nm, respectively, and Y values and 3 after standing for 1000 hours. All increase rates of the T values of 5% or less were obtained, and the luring average transmittance Y value of the composition after standing for 1000 hours at 60 ° C. and 90% relative humidity was measured, and the transmittances at wavelengths of 850 nm, 900 nm and 1000 nm were obtained. T is measured respectively, and all the rising rates of Y value and three types of T value after leaving for 1000 hours are 5% or less, The adhesive composition characterized by the above-mentioned. delete delete The method of claim 1, Pressure-sensitive adhesive composition, characterized in that used for the front plate to be mounted on the plasma display. The method of claim 1, Said (meth) acrylic-acid hydroxyalkyl ester is 2-hydroxyethyl acrylate, The adhesive composition characterized by the above-mentioned. 6. The method of claim 5, Pressure-sensitive adhesive composition, characterized in that used for the front plate to be mounted on the plasma display.