JP7247738B2 - Polyester adhesive composition, adhesive, adhesive sheet and optical member with adhesive layer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polyester pressure-sensitive adhesive composition, a pressure-sensitive adhesive, a pressure-sensitive adhesive sheet, and an optical member with a pressure-sensitive adhesive layer, and more specifically, a polyester pressure-sensitive adhesive that has a small change in haze even under high-temperature and high-humidity conditions and has excellent durability. The present invention relates to a composition, an adhesive, an adhesive sheet, and an optical member with an adhesive layer.

Conventionally, polyesters are known to be excellent in chemical resistance, mechanical strength, etc. by combining a polyvalent carboxylic acid component and a polyol component, and are also useful in the field of pressure-sensitive adhesives. As a polyester-based adhesive, for example, the adhesive disclosed in Patent Document 1 can be mentioned. In Patent Document 1, a carboxylic acid component containing 10 mol% or more and less than 50 mol% of an aromatic carboxylic acid and a polyhydric alcohol component containing 5 mol% or more of a glycol having a hydrocarbon group in a side chain are subjected to condensation polymerization. and a number-average molecular weight of 5,000 or more, and is said to have excellent adhesiveness, heat resistance, and mechanical strength.

JP 2007-45914 A

However, in recent years, adhesives are increasingly being used in the production of display devices such as liquid crystal displays (LCDs) and input devices such as touch panels used in combination with the above display devices. There is a demand for pressure-sensitive adhesives that show little change in haze under wet conditions and also have excellent durability. Although the polyester-based pressure-sensitive adhesive of Patent Document 1 is excellent in adhesiveness, heat resistance and mechanical strength, its performance under high-temperature and high-humidity conditions is not fully satisfactory, and further improvement is desired.

Under such circumstances, the present invention provides a polyester-based pressure-sensitive adhesive composition, a pressure-sensitive adhesive, a pressure-sensitive adhesive sheet, and an optical member with a pressure-sensitive adhesive layer that exhibit a small change in haze even under high-temperature and high-humidity conditions and have excellent durability. intended to provide

However, as a result of intensive research in view of such circumstances, the inventors of the present invention have found that by incorporating the hygroscopic filler [II] into the polyester resin [I], the change in haze is small even under high-temperature and high-humidity conditions, and moreover, the durability is improved. The inventors have found that it is possible to obtain a polyester-based pressure-sensitive adhesive composition having excellent properties, and completed the present invention.

That is, the first gist of the present invention is a polyester-based pressure-sensitive adhesive composition containing a polyester-based resin [I] and a hygroscopic filler [II].

A second aspect of the present invention is a pressure-sensitive adhesive obtained by cross-linking the polyester-based pressure-sensitive adhesive composition, and a third aspect is a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive. and an optical member, wherein the pressure-sensitive adhesive layer contains the pressure-sensitive adhesive.

As described above, in order to improve the wet heat durability of the polyester-based pressure-sensitive adhesive composition, it is known that the polyester-based pressure-sensitive adhesive composition contains a monomer having a side chain structure to increase cohesion and hydrophobicity. . However, the present invention is not characterized by such a method, but is characterized by containing the polyester resin [I] and the hygroscopic filler [II].
That is, the hygroscopic filler [II] has poor compatibility with the polyester resin [I], and it has been thought that turbidity occurs when used with the polyester resin [I], so it is generally not used for optical applications. is. However, unexpectedly, even if the polyester resin [I] and the hygroscopic filler [II] are used in combination, turbidity does not occur, and the hydrophilicity can be improved, even under high-temperature and high-humidity conditions. They found that the change in haze is small and the durability is excellent.

Since the polyester-based pressure-sensitive adhesive composition of the present invention contains the polyester-based resin [I] and the hygroscopic filler [II], even under high-temperature and high-humidity conditions, the haze change is small and the durability is excellent. Therefore, it is suitable for use as an adhesive for optical members.

The configuration of the present invention will be described in detail below, but these are examples of preferred embodiments.
In the present invention, the term "carboxylic acids" includes not only carboxylic acids but also carboxylic acid derivatives such as carboxylic acid salts, carboxylic acid anhydrides, carboxylic acid halides and carboxylic acid esters.

The polyester-based pressure-sensitive adhesive composition (hereinafter sometimes referred to as "pressure-sensitive adhesive composition") of the present invention is characterized by containing a polyester-based resin [I] and a hygroscopic filler [II]. The pressure-sensitive adhesive composition of the present invention comprises the polyester resin [I] and the hygroscopic filler [II] as essential components, the hydrolysis inhibitor [III], the cross-linking agent [IV] and the urethanization catalyst [V]. It preferably contains at least one selected from the group consisting of, and more preferably contains all of the hydrolysis inhibitor [III], the cross-linking agent [IV] and the urethanization catalyst [V].
Each component constituting the pressure-sensitive adhesive composition of the present invention will be described in order below.

<Polyester resin [I]>
Polyester-based resin [I] is usually obtained by copolymerizing (condensation polymerization) a copolymer component containing polyvalent carboxylic acids (A) and polyol (B) as constituent raw materials, and the polyester-based resin [I ] comes to have the structural unit derived from polyhydric carboxylic acid (A), and the structural unit derived from polyol (B) as the resin composition.

[Polyvalent carboxylic acids (A)]
Examples of the polyvalent carboxylic acid (A) used as a constituent raw material of the polyester resin [I] include divalent carboxylic acids and trivalent or higher polyvalent carboxylic acids, which stably stabilize the polyester resin [I]. Divalent carboxylic acids are preferably used because they are obtainable. These polyvalent carboxylic acids (A) can be used alone or in combination of two or more.

Examples of the divalent carboxylic acids include malonic acids, dimethylmalonic acids, succinic acids, glutaric acids, adipic acids, trimethyladipic acids, pimelic acids, 2,2-dimethylglutaric acids, azelaic acids, sebacic acids, fumaric acids, Aliphatic dicarboxylic acids such as maleic acids, itaconic acids, thiodipropionic acids, diglycolic acids, 1,9-nonanedicarboxylic acids;
Phthalic acids, terephthalic acids, isophthalic acids, benzylmalonic acids, diphenic acids, 4,4'-oxydibenzoic acids, 1,8-naphthalenedicarboxylic acids, 2,3-naphthalenedicarboxylic acids, 2,7-naphthalenedicarboxylic acids, etc. Aromatic dicarboxylic acids such as naphthalenedicarboxylic acids of;
Alicyclic groups such as 1,3-cyclopentanedicarboxylic acids, 1,2-cyclohexanedicarboxylic acids, 1,3-cyclopentanedicarboxylic acids, 1,4-cyclohexanedicarboxylic acids, 2,5-norbornanedicarboxylic acids, and adamantanedicarboxylic acids dicarboxylic acids;
etc.
Examples of the above-mentioned trivalent or higher carboxylic acids include trimellitic acids, pyromellitic acids, adamantanetricarboxylic acids, and trimesic acids.

Among the above polycarboxylic acids (A), it is preferable to contain aromatic polycarboxylic acids from the viewpoint of lowering the crystallinity of the polyester resin [I], and it is preferable to contain aromatic dicarboxylic acids (a1). is particularly preferred. Further, among the aromatic polycarboxylic acids, it is preferable to use an asymmetric aromatic polycarboxylic acid in terms of further lowering the crystallinity, and it is particularly preferable to use an asymmetric aromatic dicarboxylic acid (a1-1). preferable. Examples of such asymmetric aromatic dicarboxylic acids (a1-1) include isophthalic acid, terephthalic acid, benzylmalonic acid, diphenic acid, 4,4'-oxydibenzoic acid and naphthalenedicarboxylic acid. Among them, isophthalic acid is preferable as the asymmetric aromatic dicarboxylic acid (a1-1).

In the present invention, as the polyvalent carboxylic acid (A), from the viewpoint of improving the initial adhesive strength (tack) of the adhesive, aliphatic dicarboxylic acids (a2 ), and more preferably aliphatic dicarboxylic acids having 9 to 12 carbon atoms (including the carbon atoms of the carboxyl group) such as azelaic acid and sebacic acid.

Furthermore, in the present invention, a small amount of sulfonate group-containing dicarboxylic acids (a3) may be used as the polyvalent carboxylic acids (A). The sulfonate group-containing dicarboxylic acid (a3) is not particularly limited as long as it is a monomer component having both a dicarboxy group and a sulfonate group in the molecule. Examples thereof include sodium sulfonate and potassium sulfonate. Phthalic acid containing alkali metal sulfonates, isophthalic acid, terephthalic acid, mono- or diesters thereof are preferably used. The sulfonate group-containing dicarboxylic acids (a3) may be used alone or in combination of two or more.

Specific examples of the sulfonate group-containing dicarboxylic acids (a3) include, for example, 4-dimethylsodium sulfoisophthalate, 5-sodium sulfoisophthalate, 5-dimethylsodium sulfoisophthalate, 4-dimethylpotassium sulfoisophthalate, Potassium 5-sulfoisophthalate, sodium 2-sulfoterephthalate, potassium 2-sulfoterephthalate, sodium dimethyl 2-sulfoterephthalate, potassium dimethyl 2-sulfoterephthalate and the like. Among these, sodium 5-dimethylsulfoisophthalate is preferably used.

In the present invention, a trivalent or higher polyvalent carboxylic acid (a4) can also be used for the purpose of increasing the number of branch points in the polyester resin [I]. It is preferable to use trimellitic acids because they are less likely to occur.

[Polyol (B)]
In the present invention, examples of the polyol (B) used together with the polycarboxylic acid (A) as a constituent material of the polyester-based resin [I] include dihydric alcohols and trihydric or higher polyols.

Examples of the dihydric alcohol include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 2,4-dimethyl-2-ethylhexane-1,3-diol, 2 -methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl -1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2,2 ,4-trimethyl-1,6-hexanediol and other aliphatic diols;
1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, spiroglycol, tricyclodecanedimethanol, adamantanediol, 2,2,4,4-tetramethyl-1,3 - cycloaliphatic diols such as cyclobutanediol;
4,4'-thiodiphenol, 4,4'-methylenediphenol, 4,4'-dihydroxybiphenyl, o-, m- and p-dihydroxybenzene, 2,5-naphthalene diol, p-xylene diol and their and aromatic diols such as ethylene oxide adducts and propylene oxide adducts.
Furthermore, fatty acid esters derived from castor oil, dimer diol derived from oleic acid, erucic acid, etc., glycerol monostearate, and the like are included.
Examples of trivalent or higher polyols include pentaerythritol, dipentaerythritol, tripentaerythritol, glycerin, trimethylolpropane, trimethylolethane, 1,2,4-butanetriol, and 1,2,5-pentane. triol, 1,2,6-hexanetriol, 1,3,6-hexanetriol, adamantanetriol and the like.
These polyols (B) may be used alone or in combination of two or more.

Among the above polyols (B), it is preferable to contain a diol compound (b1) having a hydrocarbon group in a side chain from the viewpoint of increasing the number of branch points and breaking the crystallinity. Examples of the diol compound (b1) having a hydrocarbon group in the side chain include dipropylene glycol, 2,4-dimethyl-2-ethylhexane-1,3-diol, 2-methyl-1,3- Propanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2-methyl-2-ethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol , 2-ethyl-2-isobutyl-1,3-propanediol, 1,3-butanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,6-hexanediol, etc. Aliphatic diols having a branched structure, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, spiroglycol, tricyclodecanedimethanol, adamantanediol, 2,2,4 ,4-tetramethyl-1,3-cyclobutanediol and other alicyclic diols.

The diol compound (b1) having a hydrocarbon group in the side chain is preferably a diol compound having a hydrocarbon group having 1 to 6 carbon atoms, from the viewpoint of preventing crystallization while maintaining mechanical strength and heat resistance. , more preferably a diol compound having a hydrocarbon group of 1 to 4 carbon atoms, more preferably neopentyl glycol and 2-methyl-2-ethyl-1,3-propanediol.

Further, in the present invention, the polyol (B) contains an aliphatic diol (b2) having a straight chain structure in order to lower the glass transition temperature (Tg) of the polyester resin [I] and improve the initial adhesive strength. more preferably straight-chain aliphatic diols having 1 to 10 carbon atoms, and particularly preferably diethylene glycol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol. is. Among them, 1,4-butanediol and 1,6-hexanediol are particularly preferable in that the glass transition temperature (Tg) of the polyester resin [I] can be lowered and the adhesiveness becomes more excellent. .

Furthermore, in the present invention, a trivalent or higher polyol (b3) is used as the polyol (B) from the viewpoint of forming a reaction point with a cross-linking agent [IV] described later in the polyester resin [I] and increasing the cohesive force. Among them, trimethylolpropane, trimethylolethane, glycerin, pentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, and 1,2,6-hexanetriol are used. is preferred. Among these, it is preferable to use trimethylolpropane because gels are relatively unlikely to occur.

The mixing ratio of the polycarboxylic acid (A) and the polyol (B) is preferably 1 to 2 equivalents of the polyol (B) per equivalent of the polycarboxylic acid (A), particularly preferably 1.1. ~1.7 equivalents. If the blending ratio of the polyol (B) is too low, the acid value tends to increase, making it difficult to increase the molecular weight.

(Production method)
The polyester-based resin [I] used in the present invention is produced by arbitrarily selecting the above polycarboxylic acids (A) and polyol (B) and subjecting them to a polycondensation reaction by a known method in the presence of a catalyst. be.

In the polycondensation reaction, the esterification reaction is first carried out, and then the polycondensation reaction is carried out.
In such an esterification reaction, catalysts are used, and specific examples include titanium-based catalysts such as tetraisopropyl titanate and tetrabutyl titanate, antimony-based catalysts such as antimony trioxide, and germanium-based catalysts such as germanium dioxide. Catalysts and catalysts such as zinc acetate, manganese acetate, and dibutyltin oxide can be used, and one or more of these can be used. Among these, it is preferable to use antimony trioxide, tetrabutyl titanate, germanium dioxide, and zinc acetate in view of the balance between the high catalytic activity and the hue of the reaction product obtained.

The blending amount of the catalyst is preferably 1 to 10,000 ppm, more preferably 10 to 5,000 ppm, still more preferably 10 to 3,000 ppm, based on the total copolymerization components. If the amount of the catalyst is too small, the polymerization reaction tends to be difficult to proceed sufficiently.

The reaction temperature in the esterification reaction is preferably 160-280°C, particularly preferably 180-270°C, further preferably 200-260°C. If the reaction temperature is too low, the reaction tends not to proceed sufficiently, and if it is too high, side reactions such as decomposition tend to occur. Moreover, the pressure during the reaction is usually normal pressure.

The reaction time in the esterification reaction is preferably 1 to 48 hours, more preferably 1.5 to 24 hours, still more preferably 2 to 12 hours.

As the reaction conditions for the polycondensation reaction performed after the above esterification reaction, the same catalyst as used in the above esterification reaction is blended in the same amount, and the reaction temperature is preferably 220 to 280 ° C., particularly preferably. It is preferable to set the temperature to 230 to 270° C., gradually reduce the pressure in the reaction system, and finally carry out the reaction at 5 hPa or less. If the reaction temperature is too low, the reaction tends not to proceed sufficiently, and if it is too high, side reactions such as decomposition tend to occur.

The reaction time in the polycondensation reaction is preferably 1 to 48 hours, more preferably 1.5 to 24 hours, still more preferably 2 to 12 hours.

Thus, the polyester resin [I] used in the present invention is obtained.

(composition)
Polyester-based resin [I] has a structural unit derived from polycarboxylic acids (A) and a structural unit derived from polyol (B), but the structural units derived from the aromatic polycarboxylic acids are polyvalent carboxylic acids ( When it is included as a structural unit derived from A), the structural unit derived from the aromatic polycarboxylic acid is preferably 1 to 100 mol% in the structural unit derived from the polyvalent carboxylic acid (A), particularly preferably is 20 to 95 mol %, more preferably 40 to 90 mol %, particularly preferably 50 to 85 mol %, more preferably 60 to 80 mol %. If the content is too low, the cohesive strength of the adhesive tends to be low, and lifting and peeling tend to occur. initial adhesive strength (tack) tends to decrease.

The polyvalent carboxylic acids (A) preferably contain aromatic dicarboxylic acids (a1). The content ratio is preferably 1 to 100 mol%, more preferably 20 to 95 mol%, still more preferably 40 to 90 mol%, particularly preferably 1 to 100 mol% in the structural unit derived from the polyvalent carboxylic acid (A). is 50 to 85 mol %, more preferably 60 to 80 mol %. If the content is too low, the cohesive strength of the adhesive tends to be reduced, causing lifting and peeling. tend to

When the aromatic dicarboxylic acid (a1) contains an asymmetric aromatic dicarboxylic acid (a1-1), the content thereof is preferably 62 mol% or more relative to the total aromatic dicarboxylic acid (a1). , more preferably 65 mol % or more, still more preferably 70 mol % or more, and particularly preferably 80 mol % or more. If the content of the asymmetric aromatic dicarboxylic acid (a1-1) is too low, the crystallinity of the polyester resin [I] tends to increase and the solubility in solvents tends to decrease.

When the structural unit derived from the aliphatic dicarboxylic acids (a2) having 4 or more carbon atoms (including the carbon of the carboxy group) is included as a structural unit derived from the polyvalent carboxylic acids (A), the number of carbon atoms (including the carbon of the carboxy group Structural units derived from 4 or more aliphatic dicarboxylic acids (a2) containing carbon are preferably less than 99 mol% in structural units derived from polyvalent carboxylic acids (A), more preferably 5 to 80 mol %, more preferably 10 to 60 mol %, particularly preferably 15 to 50 mol %, particularly preferably 20 to 40 mol %. If the content of the aliphatic dicarboxylic acid (a2) is too high, the amount of the adhesive component tends to decrease, and the adhesive strength to polar adherends tends to decrease. If the content of the aliphatic dicarboxylic acid (a2) is too small, the glass transition temperature (Tg) of the polyester-based resin [I] tends to be high and sufficient adhesive strength cannot be obtained.

When the structural unit derived from the sulfonate group-containing dicarboxylic acids (a3) is contained as a structural unit derived from the polycarboxylic acids (A), the structural unit derived from the polycarboxylic acids (A) is 0.001 to It is preferably 10 mol %, particularly preferably 0.01 to 5 mol %, still more preferably 0.03 to 3 mol %, particularly preferably 0.05 to 2 mol %. Too little sulfonate group-containing dicarboxylic acid (a3) tends to increase haze (lower transparency) after a wet heat test, whereas too much tends to lower durability.

When the structural unit derived from the trivalent or higher polyvalent carboxylic acid (a4) is included as a structural unit derived from the polyvalent carboxylic acid (A), the structural unit derived from the trivalent or higher polyvalent carboxylic acid (a4) is preferably 10 mol % or less, more preferably 0.1 to 5 mol %, in the structural units derived from polyvalent carboxylic acids (A). If the content of the trivalent or higher polyvalent carboxylic acid (a4) is too high, gelation tends to occur during the production of the polyester resin [I].

Further, when the structural unit derived from the diol compound (b1) having a hydrocarbon group in the side chain is included as a structural unit derived from the polyol (B), the diol compound (b1) derived from the diol compound (b1) having a hydrocarbon group in the side chain is preferably 5 mol% or more, more preferably 10 to 90 mol%, still more preferably 15 to 80 mol% of the structural units derived from the polyol (B). If the content of the diol compound (b1) having a hydrocarbon group in the side chain is too small, the polyester resin [I] tends to crystallize and the initial adhesive strength of the pressure-sensitive adhesive tends to decrease. If the amount of the diol compound (b1) having a hydrogen group is too large, the reactivity tends to decrease during the production of the polyester resin [I].

When the structural unit derived from the linear aliphatic diol (b2) is included as the structural unit derived from the polyol (B), the structural unit derived from the linear aliphatic diol (b2) is a polyol It is preferably 5 to 95 mol %, more preferably 10 to 90 mol %, still more preferably 20 to 80 mol % in the structural units derived from (B). If the linear chain structure aliphatic diol (b2) is too much, the polyester resin [I] tends to crystallize and the initial adhesiveness of the pressure-sensitive adhesive tends to decrease. is too small, the reactivity tends to decrease during the production of the polyester resin [I].

Further, when the structural unit derived from the trivalent or higher polyol (b3) is included as a structural unit derived from the polyol (B), the structural unit derived from the trivalent or higher polyol (b3) is derived from the polyol (B) is preferably 10 mol % or less, more preferably 0.1 to 5 mol %, in the structural unit of If the trivalent or higher polyol (b3) is too much, the polyester resin [I] tends to gel during production, making production difficult.

Here, the structural unit ratio (composition ratio) derived from each component of the polyester resin [I] can be determined, for example, by nuclear magnetic resonance (NMR).

(physical properties)
In the present invention, the polyester resin [I] preferably has a glass transition temperature (Tg) of −20 to 30° C., more preferably −15 to 25° C., still more preferably −10 to 20° C., particularly preferably is -5 to 10°C. That is, it is preferable that the glass transition temperature of the polyester resin [I] is higher than that of a general polyester resin used in the pressure-sensitive adhesive composition, because the blister resistance will be excellent. If the glass transition temperature is too high, the flexibility of the polyester resin [I] will be lost, the initial adhesiveness of the adhesive (adhesiveness at the time of bonding to the adherend) will be reduced, and the pressure of about finger pressure will be reduced. In this case, it becomes difficult to exhibit sufficient adhesive strength, so workability is lowered. On the other hand, if the glass transition temperature is too low, the cohesive strength of the pressure-sensitive adhesive will be reduced, making it easier for the adhesive to lift and peel off.

The glass transition temperature (Tg) of the polyester resin [I] is a value measured using a differential scanning calorimeter DSC Q20 manufactured by TA Instruments. The measurement temperature range is -90 to 100°C, and the temperature rise rate is 10°C/min.

In the present invention, it is preferable that the polyester resin [I] does not crystallize from the viewpoint of storage stability. 35 J/g or less, preferably 20 J/g or less, particularly preferably 10 J/g or less, particularly preferably 5 J/g or less. Incidentally, the lower limit is usually 0 J/g.

In the present invention, the acid value of the polyether resin [I] is preferably 10 mgKOH/g or less, more preferably 5 mgKOH/g or less, still more preferably 1 mgKOH/g or less, and particularly preferably 0.5 mgKOH/g or less. be. If the acid value is too high, the pressure-sensitive adhesive layer composed of the pressure-sensitive adhesive composition of the present invention tends to be hydrolyzed and the durability tends to decrease. Further, when a metal oxide thin film layer is formed on one side of the pressure-sensitive adhesive layer, corrosion tends to occur and the electrical conductivity of the metal oxide film tends to decrease.

Here, the acid value of the polyester resin [I] is obtained by dissolving 10 g of the polyester resin [I] in a mixed solvent having a volume ratio of toluene and methanol of 7/3 (toluene/methanol), and measuring according to JIS K 0070. It is determined by neutralization titration.
In the present invention, the acid value of the polyester resin [I] means the content of carboxy groups in the resin.

The polyester resin [I] preferably has a number average molecular weight of 5,000 or more, more preferably 8,000 to 150,000, and even more preferably 10,000 to 80,000. That is, if the number average molecular weight is too low, sufficient cohesive strength as an adhesive cannot be obtained, and heat resistance and mechanical strength tend to decrease. , the initial tackiness of the adhesive tends to decrease.

In addition, the number average molecular weight in this specification is the number average molecular weight in terms of standard polystyrene molecular weight. Limit molecular weight: 2×10 ⁶ , theoretical plate number: 16,000 plates/line, filler material: styrene-divinylbenzene copolymer, filler particle size: 4 μm) are used in series. be.

<Hygroscopic filler [II]>
The pressure-sensitive adhesive composition of the present invention contains a hygroscopic filler [II] together with the polyester resin [I]. By including the hygroscopic filler [II], it is possible to increase the hydrophilicity of the adhesive, prevent the aggregation of moisture in the adhesive layer that occurs when a wet heat environmental load is applied, and reduce the haze change before and after the wet heat durability. It is small and has excellent optical properties.
The hygroscopic filler [II] is an inorganic filler having the ability to absorb moisture, and examples thereof include hygroscopic metal oxides that chemically react with absorbed moisture to form hydroxides. Such materials include, for example, at least one selected from the group consisting of calcium oxide, magnesium oxide, strontium oxide, aluminum oxide and barium oxide, or mixtures or solid solutions of two or more. Examples of the mixture or solid solution of two or more of them include calcined dolomite and calcined hydrotalcite.

Among them, calcium oxide, magnesium oxide, and calcined hydrotalcite are preferable as the hygroscopic filler [II] of the present invention, and more preferably calcined hydrotalcite, because they are excellent in hygroscopicity and supply stability and are low in cost. is. Further, from the point of view of small change in haze before and after the wet heat test, forced dehydration of a metal inorganic compound containing water of crystallization is preferable, and calcined hydrotalcite is more preferable. The forced dehydration of the metal inorganic compound containing water of crystallization is obtained by dehydrating the metal inorganic compound containing water of crystallization by heating it at a high temperature (usually 180° C. or higher) for, for example, 30 minutes or more to reduce the water content. is. The calcined hydrotalcite is produced by calcining natural hydrotalcite ( _Mg6Al2 (OH) _16CO3.4H2O ) and synthetic hydrotalcite (hydrotalcite- _like compound) to reduce the amount of OH in _the chemical structure _. reduced or eliminated. In the present invention, among the calcined hydrotalcite, a calcined synthetic hydrotalcite represented by the following general formula (1) and a calcined synthetic hydrotalcite represented by the following general formula (2) are used. preferable.

Further, the calcined hydrotalcite preferably has a BET specific surface area of 1 m ² /g or more, more preferably 2 to 2 m 2 /g, from the viewpoint of improving the transparency of the cured product of the polyester pressure-sensitive adhesive composition. 300 m ² /g, more preferably 3 to 200 m ² /g in BET specific surface area.

In the present invention, a commercially available product can also be used as the hygroscopic filler [II]. Examples of commercially available products include calcium oxide (manufactured by Sankyo Seifun Co., Ltd., Moisttop series), magnesium oxide ("Kyowa Chemical Industry Co., Ltd., Kyowamag MF150, Kyowamag MF30", "Tateho Chemical Industry Co., Ltd., PUREMAG FNM-G". ), light-burnt magnesium oxide (manufactured by Tateho Chemical Industry Co., Ltd., TATEHOMAG series), calcined dolomite (manufactured by Yoshizawa Lime Industry Co., Ltd., KT), calcined hydrotalcite (manufactured by Kyowa Chemical Industry Co., Ltd., DHT-4A, DHT-4A-2 , DHT-4C, KW-2000, KW-2100, KW-2200", "STABIACE HT-1, STABIACE HT-7, STABIACE HT-9, STABIACE HT-P" manufactured by Sakai Chemical Co., Ltd.), and the like. .

The hygroscopic filler [II] is preferably surface-treated with a surface-treating agent from the viewpoint of compatibility with the polyester-based resin [I]. Examples of the surface treatment agent that can be used include higher fatty acids, alkoxysilanes, silane coupling agents, etc. Among them, higher fatty acids and alkoxysilanes are preferably used. The above surface treatment agents may be used alone or in combination of two or more.

Examples of the higher fatty acid include higher fatty acids having 18 or more carbon atoms, such as stearic acid, montanic acid, myristic acid, and palmitic acid. Among them, stearic acid is preferred. These can be used alone or in combination of two or more.

Examples of the alkoxysilanes include methyltrimethoxysilane, ethyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, octadecyltrimethoxysilane, dimethyldimethoxysilane, octyltriethoxysilane, n-octadecyldimethyl (3-(trimethoxysilyl)propyl)ammonium chloride and the like. These can be used alone or in combination of two or more.

Examples of the silane coupling agent include 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-glycidyloxypropyl(dimethoxy)methylsilane and 2-(3,4-epoxycyclohexyl)ethyltrisilane. Epoxy silane coupling agents such as methoxysilane; Mercapto silane coupling agents such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane and 11-mercaptoundecyltrimethoxysilane Agent; 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyldimethoxymethylsilane, N-phenyl-3-aminopropyltrimethoxysilane, N-methylaminopropyltrimethoxysilane, N-( Amino-based silane coupling agents such as 2-aminoethyl)-3-aminopropyltrimethoxysilane and N-(2-aminoethyl)-3-aminopropyldimethoxymethylsilane; Ureido-based coupling agents such as 3-ureidopropyltriethoxysilane vinyl silane coupling agents such as silane coupling agents, vinyltrimethoxysilane, vinyltriethoxysilane and vinylmethyldiethoxysilane; styryl silane coupling agents such as p-styryltrimethoxysilane; Acrylate-based silane coupling agents such as methoxysilane and 3-methacryloxypropyltrimethoxysilane; isocyanate-based silane coupling agents such as 3-isocyanatopropyltrimethoxysilane, bis(triethoxysilylpropyl)disulfide, bis(triethoxysilyl) sulfide-based silane coupling agents such as propyl)tetrasulfide; phenyltrimethoxysilane, methacryloxypropyltrimethoxysilane, imidazolesilane, triazinesilane, and the like. These can be used alone or in combination of two or more.

The surface treatment of the hygroscopic filler [II] is performed, for example, by spraying the surface treatment agent onto an untreated hygroscopic filler while stirring it with a mixer at normal temperature, and then stirring for 5 to 60 minutes. It can be carried out. Examples of the mixer include blenders such as V blenders, ribbon blenders and bubble cone blenders, mixers such as Henschel mixers and concrete mixers, ball mills and cutter mills. Further, when the hygroscopic material (raw material of hygroscopic filler) is pulverized by a ball mill or the like, the surface treatment can be performed by adding and mixing the surface treatment agent. Although the surface treatment agent differs depending on the type of hygroscopic filler and surface treatment agent, it is preferable to use 1 to 10 parts by weight per 100 parts by weight of the hygroscopic filler.

The content of the hygroscopic filler [II] is preferably 0.001 to 10 parts by weight, more preferably 0.005 to 5 parts by weight, and still more preferably 100 parts by weight of the polyester resin [I]. is 0.01 to 3 parts by weight, particularly preferably 0.03 to 1 part by weight. If the content of the hygroscopic filler [II] is too high, it becomes difficult to be compatible with the polyester resin [I] and becomes cloudy, resulting in a decrease in optical properties, or the flexibility of the polyester resin [I] is impaired, resulting in a decrease in adhesive strength. tend to On the other hand, if the content of the hygroscopic filler [II] is too small, the hygroscopic performance tends to be low, and the effect of reducing the change in haze after the wet heat test tends to be insufficient.

The hygroscopic filler [II] usually has an average particle size of 1 to 5 μm, but considering its use in a pressure-sensitive adhesive composition for optical members, it is preferably 0.01 to 1 μm, more preferably 0.01 to 1 μm. It is preferably 0.01 to 0.8 μm, especially 0.01 to 0.5 μm. The hygroscopic filler [II] preferably has a particle size of 5 μm or more in an amount of 1% by weight or less, more preferably 0.3% by weight or less, based on the total hygroscopic filler [II]. The average particle size can be measured, for example, with a laser diffraction particle size distribution analyzer.

In the present invention, when the hygroscopic filler [II] is contained in the polyester resin [I], (1) the hygroscopic filler [II] is blended in the polyester resin [I], or (2) the above The hygroscopic filler [II] can be present and contained in the reaction system together with each monomer during the production of the polyester resin [I], and the point that it can be uniformly dispersed in the polyester resin [I], and the hygroscopicity The above method (2) is preferable in that the filler [II] can be dehydrated.

Further, in the present invention, when the hygroscopic filler [II] is contained in the polyester resin [I], the glass transition temperature (Tg) of the polyester resin [I] is -20 as described above. It is preferable to use a polyester resin [I] having a temperature of up to 30°C. Furthermore, it is preferable to adjust the glass transition temperature (Tg) of the mixture of the polyester resin [I] and the hygroscopic filler [II] to -20 to 30°C.

In the pressure-sensitive adhesive composition of the present invention, optional components may be used together with the polyester resin [I] and the hygroscopic filler [II]. Examples of the optional components include the hydrolysis inhibitor [III], cross-linking agent [IV] and urethanization catalyst [V]. The hydrolysis inhibitor [III] is contained to ensure long-term durability, and the cross-linking agent [IV] cross-links the polyester resin [I] to make it excellent in cohesive force. It improves the performance as Moreover, the urethanization catalyst [V] is used to adjust the curing speed. In addition to these components, within the range that does not impair the effects of the present invention, catalytic action inhibitors, antioxidants such as hindered phenols, softeners, ultraviolet absorbers, stabilizers, antistatic agents, tackifiers In addition, additives such as inorganic or organic fillers, metal powders, powders such as pigments, and particulate additives can be blended. These can be used alone or in combination of two or more.

<Hydrolysis inhibitor [III]>
As the hydrolysis inhibitor [III], conventionally known ones can be used. Examples include compounds containing functional groups such as carbodiimide groups, epoxy groups, and oxazoline groups. Among these, carbodiimide group-containing compounds are preferred because they are highly effective in extinguishing the catalytic activity of protons derived from carboxy terminal groups.

As the carbodiimide group-containing compound, a known carbodiimide having one or more carbodiimide groups (-N=C=N-) in the molecule may be used, but the durability under high temperature and high humidity is improved. is preferably a compound containing 2 or more carbodiimide groups in the molecule, i.e., a polyvalent carbodiimide compound, particularly a compound containing 3 or more, further 5 or more, especially 7 or more is preferred. If 50 or more are contained, the molecular structure tends to be too large, and the compatibility tends to decrease. It is also preferable to use a high-molecular-weight polycarbodiimide produced by a decarboxylation condensation reaction of a diisocyanate in the presence of a carbodiimidation catalyst.

Examples of such high-molecular-weight polycarbodiimides include those obtained by subjecting the following diisocyanates to a decarboxylation condensation reaction.

Such diisocyanates include, for example, 4,4'-diphenylmethane diisocyanate, 3,3'-dimethoxy-4,4'-diphenylmethane diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, 4,4'- diphenyl ether diisocyanate, 3,3′-dimethyl-4,4′-diphenyl ether diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1-methoxyphenyl-2,4-diisocyanate, isophorone diisocyanate, 4, 4'-dicyclohexylmethane diisocyanate, tetramethylxylylene diisocyanate and the like can be mentioned, and these can be used alone or in combination of two or more. Such high-molecular-weight polycarbodiimide may be synthesized or a commercially available product may be used.

Examples of commercially available carbodiimide group-containing compounds include Carbodilite (registered trademark) series manufactured by Nisshinbo Chemical Co., Ltd. Among them, Carbodilite (registered trademark) V-01, V-02B, V-03, V -04K, V-4PF, V-05, V-07, V-09, and V-09GB are preferable because of their excellent compatibility with organic solvents.

In addition, the carbodiimide equivalent when using the carbodiimide group-containing compound is preferably 50 to 10,000, particularly 100 to 1,000, further preferably 150 to 500. The carbodiimide equivalent is the chemical formula weight per carbodiimide group.

Preferred examples of the epoxy group-containing compound include glycidyl ester compounds and glycidyl ether compounds.

Specific examples of glycidyl ester compounds include glycidyl benzoate, t-butyl-benzoic acid glycidyl ester, p-toluic acid glycidyl ester, cyclohexanecarboxylic acid glycidyl ester, pelargonic acid glycidyl ester, stearic acid glycyl ester, and lauric acid. glycidyl ester, glycidyl palmitate, glycidyl behenate, glycidyl versatate, glycidyl oleate, glycidyl linoleate, glycidyl linoleate, glycidyl behenoleate, glycidyl stearate, diglycidyl terephthalate, Diglycidyl isophthalate, diglycidyl phthalate, diglycidyl naphthalene dicarboxylate, diglycidyl methyl terephthalate, diglycidyl hexahydrophthalate, diglycidyl tetrahydrophthalate, diglycidyl cyclohexanedicarboxylate, adipic acid diglycidyl ester, diglycidyl succinate, diglycidyl sebacate, diglycidyl dodecanedioate, diglycidyl octadecanedicarboxylate, triglycidyl trimellitate, tetraglycidyl pyromellitic acid, and the like. They can be used alone or in combination of two or more.

Specific examples of glycidyl ether compounds include phenylglycidyl ether, o-phenylglycidyl ether, 1,4-bis(β,γ-epoxypropoxy)butane, 1,6-bis(β,γ- epoxypropoxy)hexane, 1,4-bis(β,γ-epoxypropoxy)benzene, 1-(β,γ-epoxypropoxy)-2-ethoxyethane, 1-(β,γ-epoxypropoxy)-2- benzyloxyethane, 2,2-bis-[р-(β,γ-epoxypropoxy)phenyl]propane and 2,2-bis-(4-hydroxyphenyl)propane and 2,2-bis-(4-hydroxyphenyl ) bisglycidyl polyether obtained by reaction of bisphenol such as methane and epichlorohydrin, and the like, and these can be used alone or in combination of two or more.

A bisoxazoline compound or the like is preferable as the oxazoline group-containing compound. Specifically, for example, 2,2′-bis(2-oxazoline), 2,2′-bis(4-methyl-2-oxazoline), 2,2′-bis(4,4-dimethyl-2- oxazoline), 2,2'-bis(4-ethyl-2-oxazoline), 2,2'-bis(4,4'-diethyl-2-oxazoline), 2,2'-bis(4-propyl-2 -oxazoline), 2,2′-bis(4-butyl-2-oxazoline), 2,2′-bis(4-hexyl-2-oxazoline), 2,2′-bis(4-phenyl-2-oxazoline) ), 2,2′-bis(4-cyclohexyl-2-oxazoline), 2,2′-bis(4-benzyl-2-oxazoline), 2,2′-p-phenylenebis(2-oxazoline), 2 , 2′-m-phenylenebis(2-oxazoline), 2,2′-o-phenylenebis(2-oxazoline), 2,2′-p-phenylenebis(4-methyl-2-oxazoline), 2, 2′-p-phenylenebis(4,4-dimethyl-2-oxazoline), 2,2′-m-phenylenebis(4-methyl-2-oxazoline), 2,2′-m-phenylenebis(4, 4-dimethyl-2-oxazoline), 2,2′-ethylenebis(2-oxazoline), 2,2′-tetramethylenebis(2-oxazoline), 2,2′-hexamethylenebis(2-oxazoline), 2,2'-octamethylenebis(2-oxazoline), 2,2'-decamethylenebis(2-oxazoline), 2,2'-ethylenebis(4-methyl-2-oxazoline), 2,2'- Tetramethylenebis(4,4-dimethyl-2-oxazoline), 2,2'-9,9'-diphenoxyethanebis(2-oxazoline), 2,2'-cyclohexylenebis(2-oxazoline), 2 ,2'-diphenylenebis(2-oxazoline) and the like can be exemplified, and among these, 2,2'-bis(2-oxazoline) is most preferable from the viewpoint of reactivity with polyester.
Moreover, these can be used individually or in combination of 2 or more types.

As these hydrolysis inhibitors [III], those having low volatility are preferable, and therefore those having a high number average molecular weight are preferably used, usually 300 to 15,000, preferably 1,000 to 10,000. Use the one from
As the hydrolysis inhibitor [III], one having a high weight-average molecular weight is preferably used from the viewpoint of hydrolysis resistance. The weight average molecular weight of the hydrolysis inhibitor [III] is preferably 500 or more, more preferably 2,000 or more, even more preferably 3,000 or more. In addition, the upper limit of the weight average molecular weight is usually 50,000.
If the hydrolysis inhibitor [III] has too small a molecular weight, the hydrolysis resistance tends to decrease. On the other hand, if the molecular weight is too large, the compatibility with the polyester resin [I] tends to decrease.

In addition, the weight average molecular weight in this specification is the weight average molecular weight in terms of standard polystyrene molecular weight. 2×10 ⁶ , theoretical plates: 16,000 plates/line, filler material: styrene-divinylbenzene copolymer, filler particle diameter: 4 μm) are used in series.

The content of the hydrolysis inhibitor [III] is preferably 0.01 to 10 parts by weight, particularly preferably 0.1 to 5 parts by weight, relative to 100 parts by weight of the polyester resin [I]. , more preferably 0.2 to 3 parts by weight, particularly preferably 0.3 to 1.5 parts by weight.
If the content is too large, turbidity tends to occur due to poor compatibility with the polyester resin [I], and if it is too small, it tends to be difficult to obtain sufficient durability.

Further, the content of the hydrolysis inhibitor [III] is preferably optimized according to the acid value of the polyester resin [I], and the polyester resin [I The molar ratio (T) of the total number of moles of the functional groups of the hydrolysis inhibitor [III] in the pressure-sensitive adhesive composition to the total number of moles of the acidic functional groups of ] is 0.5 ≤ (T) is preferred, particularly preferably 1≤(T)≤1,000, more preferably 1.5≤(T)≤100.
If the molar ratio (T) is too low, the wet heat resistance tends to be lowered. Conversely, if the molar ratio (T) is too high, the compatibility with the polyester resin [I] tends to decrease, or the adhesive strength, cohesive strength, and durability tend to decrease.

<Crosslinking agent [IV]>
Examples of the cross-linking agent [IV] include compounds having a functional group that reacts with at least one of a hydroxyl group and a carboxy group contained in the polyester resin [I], such as polyisocyanate compounds and polyepoxy compounds. Among these, it is particularly preferable to use a polyisocyanate-based compound from the viewpoint of achieving a good balance between initial adhesive strength, mechanical strength, and heat resistance.

Examples of such polyisocyanate compounds include tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, tetramethylxylylene diisocyanate, 1 , 5-naphthalene diisocyanate, triphenylmethane triisocyanate and the like polyisocyanates, and adducts of the above polyisocyanates with polyol compounds such as trimethylolpropane, burettes of these polyisocyanate compounds, and isocyanurates. A body etc. are mentioned. The above polyisocyanate-based compound may also be one in which the isocyanate portion is blocked with phenol, lactam, or the like. These cross-linking agents [IV] may be used singly or in combination of two or more.

The content of the cross-linking agent [IV] can be appropriately selected depending on the molecular weight of the polyester resin [I] and the purpose of use, but is usually 1 equivalent of at least one of hydroxyl groups and carboxy groups contained in the polyester resin [I]. The reactive group contained in the cross-linking agent [IV] preferably contains the cross-linking agent [IV] at a rate of 0.2 to 10 equivalents, particularly preferably 0.5 to 5 equivalents, and further It is preferably 0.5 to 3 equivalents.
If the number of equivalents of the reactive groups contained in the cross-linking agent [IV] is too small, the cohesive force tends to decrease, and if it is too large, the flexibility tends to decrease.

In addition, in the reaction between the polyester resin [I] and the cross-linking agent [IV], an organic solvent having no functional group that reacts with these [I] and [IV] components, for example, esters such as ethyl acetate and butyl acetate organic solvents such as ketones such as ketones, methyl ethyl ketone and methyl isobutyl ketone, and aromatics such as toluene and xylene. These can be used alone or in combination of two or more.

<Urethane catalyst [V]>
As the urethanization catalyst [V], for example, an organometallic compound, a tertiary amine compound, or the like can be used. These can be used alone or in combination of two or more.

Examples of the organometallic compounds include zirconium-based compounds, iron-based compounds, tin-based compounds, titanium-based compounds, lead-based compounds, cobalt-based compounds, and zinc-based compounds.
Examples of zirconium-based compounds include zirconium naphthenate and zirconium acetylacetonate.
Examples of iron-based compounds include iron acetylacetonate and iron 2-ethylhexanoate.
Examples of tin-based compounds include dibutyltin dichloride, dibutyltin oxide, and dibutyltin dilaurate.
Examples of titanium compounds include dibutyltitanium dichloride, tetrabutyltitanate, butoxytitanium trichloride and the like.
Examples of lead compounds include lead oleate, lead 2-ethylhexanoate, lead benzoate, and lead naphthenate.
Examples of cobalt-based compounds include cobalt 2-ethylhexanoate and cobalt benzoate.
Examples of zinc-based compounds include zinc naphthenate and zinc 2-ethylhexanoate.

Examples of the tertiary amine compound include triethylamine, triethylenediamine, 1,8-diazabicyclo-(5,4,0)-undecene-7 and the like.

Among these urethanization catalysts [V], organometallic compounds are preferred, zirconium compounds are particularly preferred, and zirconium acetylacetonate is particularly preferred, in terms of reaction rate and pot life of the adhesive layer. .

<Catalytic action inhibitor>
In the pressure-sensitive adhesive composition of the present invention, the urethanization catalyst [V] preferably contains a catalytic action inhibitor in order to extend the pot life and improve the coatability.
Examples of catalytic action inhibitors include β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, octyl acetoacetate, oleyl acetoacetate, lauryl acetoacetate, and stearyl acetoacetate, acetylacetone, 2,4-hexanedione, and benzoylacetone. and β-diketones such as These are keto-enol tautomeric compounds, and by protecting the urethanization catalyst [V], they reduce the catalytic activity of the urethanization catalyst [V] in a solution state, resulting in excessive Viscosity increase and gelation can be suppressed, and the pot life of the pressure-sensitive adhesive composition can be extended.
Among these, it is preferable to use acetylacetone as the catalytic action inhibitor from the viewpoint of the balance between pot life and curing speed. These catalytic action inhibitors can be used singly or in combination of two or more.
The compounding ratio (weight ratio) of the catalytic action inhibitor and the urethanization catalyst [V] is preferably in the range of catalytic action inhibitor: urethanization catalyst [V] = 0.001: 1 to 15: 1, and further It is preferably 0.005:1 to 13:1, particularly preferably 0.01:1 to 10:1. If the content of the catalytic action inhibitor is too small relative to the content of the urethanization catalyst [V], the pot life tends to be short and the coatability tends to deteriorate.

<Antioxidant>
The pressure-sensitive adhesive composition of the present invention preferably further contains an antioxidant from the viewpoint of improving heat resistance. By containing the antioxidant, the decrease in the molecular weight of the polyester resin [I] in a heat-resistant environment is suppressed, and the adhesive residue prevention property on the adherend is excellent.
As the antioxidant, an antioxidant having a hindered phenol structure is preferred.
As an antioxidant having a hindered phenol structure, for example, a group having a large steric hindrance such as a tertiary butyl group is bonded to at least one of the carbon atoms adjacent to the carbon atoms on the aromatic ring to which the hydroxyl group of phenol is bonded. An antioxidant having a hindered phenol structure is mentioned. By using such an antioxidant, the effect of suppressing the decrease in the molecular weight of the polyester resin [I] in a heat-resistant environment is greatly enhanced.
The content of the antioxidant is preferably 0.01 to 10 parts by weight, more preferably 0.03 to 8 parts by weight, and still more preferably 0 parts by weight with respect to 100 parts by weight of the polyester resin [I]. 0.05 to 5 parts by weight.
If the content is too small, adhesive residue tends to be easily generated on the adherend, and if the content is too large, adhesive physical properties tend to deteriorate.

The pressure-sensitive adhesive composition of the present invention may contain, in addition to the above additives, a small amount of impurities contained in raw materials for manufacturing constituent components of the pressure-sensitive adhesive composition.

Such a pressure-sensitive adhesive composition can be prepared, for example, by preparing the polyester resin [I], the hygroscopic filler [II] and necessary optional components, and blending and dispersing them during the production of the polyester resin [I]. Alternatively, it can be obtained by blending with a polyester resin [I] solution dissolved in an organic solvent and dispersing it using a mixing roller.

Moreover, the pressure-sensitive adhesive according to the present invention comprises the pressure-sensitive adhesive composition, that is, the pressure-sensitive adhesive composition is crosslinked (cured).

The pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer on one or both sides of a support substrate, and is particularly suitable as a pressure-sensitive adhesive sheet for optical members used for laminating optical members.
In the present invention, the term "sheet" includes "film" and "tape".

<Adhesive sheet>
The adhesive sheet can be produced, for example, as follows.
As a method for producing such a pressure-sensitive adhesive sheet, it can be produced according to a known general method for producing a pressure-sensitive adhesive sheet. A pressure-sensitive adhesive layer in which a pressure-sensitive adhesive composition is crosslinked on a substrate by forming a layer, laminating a release sheet on the surface (the surface opposite to the surface in contact with the substrate), and curing if necessary. A pressure-sensitive adhesive sheet of the present invention having

Alternatively, the pressure-sensitive adhesive composition is applied onto a release sheet and dried to form a pressure-sensitive adhesive layer. The pressure-sensitive adhesive sheet of the present invention can also be obtained by curing with.

Then, by forming a pressure-sensitive adhesive layer on a release sheet and bonding the release sheet and another release sheet to the surface (the opposite side of the surface in contact with the release sheet), a substrate-less double-sided pressure-sensitive adhesive sheet can be obtained. can be manufactured.

When using the obtained pressure-sensitive adhesive sheet or substrate-less double-sided pressure-sensitive adhesive sheet, the release sheet is peeled off from the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer and the adherend are bonded together.

Examples of the base material include polyester resins such as polyethylene naphtate, polyethylene terephthalate, polybutylene terephthalate, and polyethylene terephthalate/isophthalate copolymer; polyolefin resins such as polyethylene, polypropylene, and polymethylpentene; polyvinyl fluoride; Polyethylene fluoride resins such as polyvinylidene fluoride and polyethylene fluoride; polyamides such as nylon 6 and nylon 6,6; polyvinyl chloride, polyvinyl chloride/vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl Vinyl polymers such as alcohol copolymers, polyvinyl alcohol and vinylon; Cellulose resins such as cellulose triacetate and cellophane; Acrylic resins such as polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate and polybutyl acrylate. polystyrene; polycarbonate; polyarylate; polyimide; synthetic resin sheets such as cycloolefin polymers; metal foils of aluminum, copper and iron; A nonwoven fabric is mentioned. These substrates can be used as a single-layer body or as a multi-layer body in which two or more types are laminated.

Among these, substrates made of polyethylene terephthalate and polyimide are particularly preferable, and polyethylene terephthalate is particularly preferable in that it has excellent adhesiveness with an adhesive. It is preferable in that it has excellent adhesion to the adhesive, can keep the substrate stable without corroding the metal thin film layer, and can exhibit the effect of the adhesive used in the present invention remarkably.

In the present invention, the ITO electrode film is formed as a thin film on a polyethylene terephthalate (PET) base material, and has an adhesive layer on the PET side of the film. )-based film and further an acrylic film (layer configuration: ITO electrode film/PET substrate/adhesive layer/PC-based film/acrylic-based film).

As the release sheet, for example, the various synthetic resin sheets, paper, cloth, non-woven fabric, etc. exemplified in the above substrates, which have undergone a release treatment, can be used. Among them, it is preferable to use a silicon-based release sheet as the release sheet.

The thickness of the substrate is, for example, preferably 1 to 1,000 μm, particularly preferably 2 to 500 μm, further preferably 3 to 300 μm.

As the coating method of the pressure-sensitive adhesive composition, for example, a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, a spray coater, a comma coater and the like may be used.

The conditions for the curing treatment are usually room temperature (23° C.) to 70° C., and the time is usually 1 to 30 days. It may be carried out under conditions such as up to 14 days, 40° C. for 1 to 10 days, and the like.

As the drying conditions after coating the adhesive composition, the drying temperature is preferably 60 to 140.degree. C., particularly preferably 80 to 120.degree. The drying time is preferably 0.5 to 30 minutes, particularly preferably 1 to 5 minutes.

The thickness of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet and the substrate-less double-sided pressure-sensitive adhesive sheet is preferably 2 to 500 μm, particularly preferably 5 to 200 μm, further preferably 10 to 100 μm. If the thickness of the pressure-sensitive adhesive layer is too thin, the adhesive strength tends to decrease. be. In addition, it is preferable to make it 50 micrometers or more when considering impact absorption.

The thickness of the pressure-sensitive adhesive layer is obtained by subtracting the measured thickness of the constituent members other than the pressure-sensitive adhesive layer from the measured value of the thickness of the entire pressure-sensitive adhesive sheet using a digimatic indicator (manufactured by Mitutoyo Co., Ltd., ID-C112B). It is a value obtained by

The gel fraction of the pressure-sensitive adhesive layer is preferably 10% by weight or more, particularly preferably 15-95% by weight, further preferably 20-90% by weight, from the viewpoint of durability and adhesive strength. If the gel fraction is too low, cohesive strength tends to decrease, resulting in a decrease in durability. In addition, if the gel fraction is too high, there is a concern that the cohesive force will increase and the adhesive force will decrease.

The gel fraction is a measure of the degree of cross-linking, and is calculated, for example, by the following method. That is, a pressure-sensitive adhesive sheet (without a separator) in which a pressure-sensitive adhesive layer is formed on a polymer sheet (for example, PET film, etc.) serving as a base material is wrapped in a 200-mesh SUS wire mesh, and placed in toluene at 23 ° C. After immersion for 24 hours, the weight percentage of the undissolved adhesive component remaining in the wire mesh after immersion with respect to the weight of the adhesive component before immersion is defined as the gel fraction. However, the weight of the base material is subtracted.

Furthermore, such a pressure-sensitive adhesive sheet may be provided with a release sheet outside the pressure-sensitive adhesive layer to protect the pressure-sensitive adhesive layer, if necessary. In a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed on one side of a base material, the side opposite to the pressure-sensitive adhesive layer of the base material is subjected to a release treatment so that the pressure-sensitive adhesive layer can be removed using the release-treated surface. can also be protected.

Moreover, the pressure-sensitive adhesive of the present invention can be used for bonding various members, but it is particularly preferable to use it as a pressure-sensitive adhesive for optical members, which is used for bonding optical members. By laminating a pressure-sensitive adhesive layer of the pressure-sensitive adhesive composition on an optical member, the pressure-sensitive adhesive layer-attached optical member can be obtained.

Examples of such optical members include ITO electrode films, transparent electrode films such as inorganic or organic conductive films such as polythiophene, polarizing plates, retardation plates, elliptically polarizing plates, optical compensation films, brightness enhancement films, electromagnetic wave shielding films, An infrared absorbing film, an AR (anti-reflection) film, and the like are included. Among these, an ITO electrode film is particularly preferable because it is effective when the optical member is a transparent electrode film and high adhesive strength can be obtained. The ITO electrode film is often formed as a thin film on a substrate such as glass or PET. Especially preferred.
It is also suitable for use as a light extraction film provided on the light emitting surface of a surface light emitter of an organic EL device, or as a light diffusion sheet for a liquid crystal display.

It is preferable to further provide a release film on the surface of the pressure-sensitive adhesive layer opposite to the optical member surface of the pressure-sensitive adhesive layer-attached optical member. The pressure-sensitive adhesive layer and the adherend are laminated. As such a release film, it is preferable to use a silicon-based release film.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the examples, "parts" and "%" mean weight basis (excluding "haze change").
Further, the measurement of the glass transition temperature of the polyester resin [I] in the following examples was carried out according to the method described above.

<Production of polyester resin [I]>
The mol % of the polyvalent carboxylic acids (A) described in the following production examples indicates the molar ratio when the total amount of the polyvalent carboxylic acids (A) is 100 mol %.
Moreover, the mol % of the polyol (B) described in the following production examples indicates the molar ratio when the total amount of the polyol (B) is 100 mol %.

[Production of polyester resin [I-1]]
248.3 parts of isophthalic acid (IPA) and 129 parts of sebacic acid (SebA) as polyvalent carboxylic acids (A) were placed in a reactor equipped with a heating device, a thermometer, a stirrer, a rectifying column, a nitrogen inlet tube and a vacuum device. .6 parts, 96.2 parts of 1,4-butanediol (1,4BG) as polyol (B), 200.2 parts of neopentyl glycol (NPG), 21.4 parts of 1,6-hexanediol (1,6HG) 4.3 parts of trimethylolpropane (TMP), 0.5 parts of hygroscopic filler [II] (manufactured by Kyowa Chemical Industry Co., Ltd.; DTH-4A-2), 0.05 parts of zinc acetate as a catalyst, and the internal temperature The temperature was gradually raised to 250° C., and the esterification reaction was carried out over 4 hours.
Then, the internal temperature was raised to 260° C., 0.05 part of tetrabutyl titanate was added as a catalyst, the pressure was reduced to 1.33 hPa, and polymerization was carried out over 3 hours to produce a polyester resin [I-1].
The obtained polyester resin [I-1] had a glass transition temperature of 3.0° C., and the finished component ratio was isophthalic acid/sebacic acid=70 mol %/30 mol % as polyvalent carboxylic acids (A), polyol ( B) was 1,4-butanediol/neopentyl glycol/1,6-hexanediol/trimethylolpropane=34 mol %/58.5 mol %/6 mol %/1.5 mol %.

[Production of polyester resin [I-2]]
236.5 parts of isophthalic acid (IPA) and 141 parts of sebacic acid (SebA) as polyvalent carboxylic acids (A) were placed in a reactor equipped with a heating device, thermometer, stirrer, rectifying column, nitrogen inlet tube and vacuum device. .8 parts, 0.3 parts of 5-dimethylsodium sulfoisophthalate (SIPM), 95.7 parts of 1,4-butanediol (1,4BG) as polyol (B), and 221.3 parts of neopentyl glycol (NPG) , 4.3 parts of trimethylolpropane (TMP), 0.5 parts of hygroscopic filler [II] (manufactured by Kyowa Chemical Industry Co., Ltd., KW-2200), and 0.05 parts of zinc acetate as a catalyst are charged, and the internal temperature is up to 250 ° C. The temperature was gradually raised, and the esterification reaction was carried out over 4 hours.
Thereafter, the internal temperature was raised to 260° C., 0.05 part of tetrabutyl titanate was added as a catalyst, the pressure was reduced to 1.33 hPa, and polymerization was carried out over 3 hours to produce a polyester resin [I-2].
The obtained polyester resin [I-2] had a glass transition temperature of 4.9° C., and the composition ratio of the finished product was isophthalic acid/sebacic acid/sodium dimethyl 5-sulfoisophthalate as the polyvalent carboxylic acid (A)=66. 97 mol %/32.98 mol %/0.05 mol %, 1,4-butanediol/neopentyl glycol/trimethylolpropane=33.8 mol %/64.7 mol %/1.05 mol % as polyol (B). It was 5 mol %.

[Production of polyester resin [I-3]]
248.3 parts of isophthalic acid (IPA) and 129 parts of sebacic acid (SebA) as polyvalent carboxylic acids (A) were placed in a reactor equipped with a heating device, a thermometer, a stirrer, a rectifying column, a nitrogen inlet tube and a vacuum device. .6 parts, 96.2 parts of 1,4-butanediol (1,4BG) as polyol (B), 200.2 parts of neopentyl glycol (NPG), 21.4 parts of 1,6-hexanediol (1,6HG) 4.3 parts of trimethylolpropane (TMP) and 0.05 part of zinc acetate as a catalyst were charged, and the internal temperature was gradually raised to 250° C., and an esterification reaction was carried out over 4 hours.
Thereafter, the inner temperature was raised to 260° C., 0.05 part of tetrabutyl titanate was charged as a catalyst, the pressure was reduced to 1.33 hPa, and polymerization was carried out over 3 hours to produce a polyester resin [I-3].
The obtained polyester resin [I-3] had a glass transition temperature of 1.0° C., and the finished component ratio was isophthalic acid/sebacic acid=70 mol %/30 mol % as polyvalent carboxylic acids (A), polyol ( B) with 1,4-butanediol/neopentyl glycol/1,6-hexanediol/trimethylolpropane (TMP) = 34 mol%/58.5 mol%/6.2 mol%/1.3 mol% there were.

The results of the resin composition (structural units derived from the components) and the glass transition temperature (Tg) of the obtained polyester resin [I] are also shown in Table 1 below.

<Production of adhesive composition>
Using the polyester resins [I-1], [I-2] and [I-3] obtained above, adhesive compositions were produced as follows.

(Example 1)
The polyester resin [I-1] obtained above was diluted with toluene to a solid content concentration of 50%, and this polyester resin [I-1] solution (100 parts as solid content) was added with a hydrolysis inhibitor [ III] (manufactured by Nisshinbo Chemical Co., Ltd., Carbodilite V-09BG) 0.7 parts (solid content), and as a cross-linking agent [IV] trimethylolpropane / tolylene diisocyanate adduct (manufactured by Tosoh Corporation, Coronate L55E) 4 parts (solid ), 0.02 part (solid content) of a zirconium compound diluted with acetylacetone to a solid content concentration of 1% (manufactured by Matsumoto Fine Chemicals Co., Ltd., Orgatics ZC-150) as a urethanization catalyst [V] is added, stirred and mixed. Thus, an adhesive composition was obtained.

(Example 2)
Example 1 except that the polyester resin [I-1] in Example 1 was changed to polyester resin [I-2] and the amount of the cross-linking agent [IV] was changed to 5 parts (solid content). A pressure-sensitive adhesive composition was obtained in the same manner as above.

(Comparative example 1)
In Example 1, polyester resin [I-1] was changed to polyester resin [I-3], and the amount of cross-linking agent [IV] was changed to 2.5 parts (solid content). Other than that, it carried out similarly to Example 1, and obtained the adhesive composition. That is, in Comparative Example 1, the hygroscopic filler [II] was not used.

The pressure-sensitive adhesive composition thus obtained was evaluated as follows, and the results are shown in Table 2 below.

<Production of double-sided adhesive sheet without base material>
The pressure-sensitive adhesive compositions obtained in Examples 1 and 2 and Comparative Example 1 were applied to a 100 μm-thick PET release film (manufactured by Mitsui Chemicals Tohcello, SP-PET-03-BU) (α) with an applicator. and dried at 100° C. for 4 minutes to obtain an adhesive sheet with a release film having an adhesive layer thickness of 50 μm.
Next, the pressure-sensitive adhesive layer surface of the pressure-sensitive adhesive sheet with a release film obtained above is a PET release film (manufactured by Mitsui Chemicals Tocello Co., Ltd., SP-PET-01 -BU) (β) and cured at 40°C for 4 days to obtain a substrate-less double-sided pressure-sensitive adhesive sheet.

<Adhesive sheet evaluation>
[Haze change]
The release film (β) on one side was peeled off from the pressure-sensitive adhesive layer of the substrate-less double-sided pressure-sensitive adhesive sheet obtained above, and the pressure-sensitive adhesive layer was transferred to a PET film (100 μm) to prepare a pressure-sensitive adhesive sheet for evaluation. . After peeling off the separator on the other side from the obtained pressure-sensitive adhesive sheet for evaluation and bonding the exposed pressure-sensitive adhesive layer to a non-alkali glass plate (manufactured by Corning, Eagle XG), autoclave treatment (50 ° C., 0.5 MPa for 20 minutes) to prepare a test piece having a configuration of PET film/adhesive layer/non-alkali glass plate.
A wet heat test (85° C., 85% RH, 100 hours) was performed on the test piece, and the haze before the test and 30 minutes after taking out the test was measured using a HAZE MATER NDH2000 (manufactured by Nippon Denshoku Industries Co., Ltd.). Then, the displacement was calculated and evaluated according to the following criteria. The results are also shown in Table 2 below. This machine complies with JIS K7361-1.
(Evaluation criteria)
Haze displacement (%) = Haze value (%) after wet heat test - Haze value (%) before wet heat test
⊚ (very good): Haze displacement less than 5%.
◯ (good): Haze displacement of 5 or more and less than 10%.
Δ (average): haze displacement of 10 or more and less than 15%.
× (bad): Haze displacement of 15% or more.

[Adhesiveness at high temperature: 180 degree peel strength (N/25 mm)]
The release film (β) on one side of the substrate-less double-sided pressure-sensitive adhesive sheet obtained above was peeled off, and the adhesive layer was transferred to a PET film (100 μm) to prepare a pressure-sensitive adhesive sheet for evaluation. The separator on the other side of the obtained adhesive sheet for evaluation was peeled off, and the exposed adhesive layer was attached to a polycarbonate plate (manufactured by Mitsubishi Chemical Corporation, Stella). 5 MPa for 20 minutes) to prepare a test piece having a configuration of PET film/adhesive layer/polycarbonate plate.
Using a tensile tester with a constant temperature bath (Autograph AGS-H 500N, manufactured by Shimadzu Corporation), the test piece was measured for 180 degree peel strength at 85° C. and a peel rate of 300 mm/min. The results are also shown in Table 2.

[Blister resistance]
The release film (β) on one side of the substrate-less double-sided pressure-sensitive adhesive sheet obtained above was peeled off, and the adhesive layer was transferred to a PET film (100 μm) to prepare a pressure-sensitive adhesive sheet for evaluation. The separator on the other side of the obtained adhesive sheet for evaluation was peeled off, and the exposed adhesive layer was attached to a polycarbonate plate (manufactured by Mitsubishi Chemical Corporation, Stella). 5 MPa for 20 minutes) to prepare a test piece having a configuration of PET film/adhesive layer/polycarbonate plate.
The test piece was subjected to a load for 24 hours in a constant temperature and humidity bath (85° C., 85% RH), and the appearance of the test piece after the load (presence or absence of foaming) was visually observed and evaluated according to the following criteria. The results are also shown in Table 2.
(Evaluation criteria)
⊚ (very good): no foaming and no change in appearance.
◯ (good): The portion where foaming occurred was 1/4 or less of the area of the test piece.
Δ (Normal): The portion where foaming occurred was more than 1/4 and 1/2 or less of the area of the test piece.
x (bad): The portion where foaming occurred exceeded 1/2 of the area of the test piece.

From the results in Table 2 above, it can be seen that the pressure-sensitive adhesive compositions of Examples 1 and 2 not only have excellent high-temperature tackiness and blister resistance, but also have very small changes in haze even under high-temperature and high-humidity conditions.
On the other hand, the pressure-sensitive adhesive composition of Comparative Example 1 was excellent in high-temperature pressure-sensitive adhesiveness and blister resistance, but had extremely large changes in haze and was inferior in performance as a pressure-sensitive adhesive.
In addition, it is generally known that adhesive compositions using urethane-based resins or acrylic-based resins have weak adhesive strength at high temperatures and poor blister resistance. Therefore, in the present invention, it is important to use the polyester resin [I]. Further, by using the polyester resin [I] and the hygroscopic filler [II] in combination, under high temperature and high humidity conditions, haze can be reduced. The pressure-sensitive adhesive composition is excellent in terms of change, adhesiveness, and blister resistance.

Since the pressure-sensitive adhesive composition of the present invention is excellent in all of haze change, adhesiveness and blister resistance under high-temperature and high-humidity conditions, the pressure-sensitive adhesive and pressure-sensitive adhesive sheet using it are suitable for displays and optical films constituting them. and optical members such as base materials, it can be suitably used for laminating the optical members.

Claims (13)

A polyester adhesive composition containing a polyester resin [I] and a hygroscopic filler [II], wherein the hygroscopic filler [II] has an average particle size of 1 μm or less. agent composition. The polyester pressure-sensitive adhesive composition according to claim 1, wherein the polyester resin [I] has a glass transition temperature (Tg) of -20 to 30°C. The polyester resin [I] has a structural unit derived from a polycarboxylic acid (A) and a structural unit derived from a polyol (B), and the polyvalent carboxylic acid (A) is an aromatic dicarboxylic acid (a1 ), and the polyol (B) contains a diol compound (b1) having a hydrocarbon group in a side chain. 4. The polyester pressure-sensitive adhesive composition according to any one of claims 1 to 3, wherein the hygroscopic filler [II] is a forced dehydration product of a metallic inorganic compound containing water of crystallization. 5. The polyester pressure-sensitive adhesive composition according to any one of claims 1 to 4, further comprising a hydrolysis inhibitor [III]. 6. The polyester pressure-sensitive adhesive composition according to any one of claims 1 to 5, further comprising a cross-linking agent [IV]. 7. The polyester pressure-sensitive adhesive composition according to any one of claims 1 to 6, further comprising a urethanization catalyst [V]. 8. A pressure-sensitive adhesive obtained by cross-linking the polyester-based pressure-sensitive adhesive composition according to any one of claims 1 to 7. A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive according to claim 8 . 10. The adhesive sheet according to claim 9, comprising a substrate and an adhesive layer, wherein the adhesive layer is provided on at least one side of the substrate. 10. The pressure-sensitive adhesive sheet according to claim 9, which is a substrate-less type pressure-sensitive adhesive sheet having no substrate. 12. The pressure-sensitive adhesive sheet according to any one of claims 9 to 11, which is used for bonding optical members. An optical member with a pressure-sensitive adhesive layer, comprising a pressure-sensitive adhesive layer and an optical member, wherein the pressure-sensitive adhesive layer contains the pressure-sensitive adhesive according to claim 8 .