JP2022153322A - Polyester-based adhesive composition, polyester-based adhesive, adhesive sheet, and optical member with adhesive member layer - Google Patents

Abstract

To provide a polyester-based adhesive composition which is excellent in initial adhesive force, optical characteristics and moisture heat whitening resistance under high temperature and high humidity.SOLUTION: A polyester-based adhesive composition contains a polyester-based resin (A), polyoxyalkylene polyol (B), and a hydrolysis suppressor (C), where a content of the polyoxyalkylene polyol (B) is 0.01-10 pts.wt. with respect to 100 pts.wt. of the polyester-based resin (A).SELECTED DRAWING: None

Description

The present invention relates to a polyester pressure-sensitive adhesive composition, a polyester pressure-sensitive adhesive, a pressure-sensitive adhesive sheet, and an optical member with a pressure-sensitive adhesive layer. A polyester-based pressure-sensitive adhesive composition having excellent properties, a pressure-sensitive adhesive obtained by cross-linking the pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive, and an optical member with a pressure-sensitive adhesive layer having the pressure-sensitive adhesive layer Regarding.

Polyester-based resins are known to be excellent in chemical resistance, plasticizer resistance, mechanical strength, etc. by combining a polyvalent carboxylic acid component and a polyol component. It is also being considered for use in the field of adhesives).
In addition, mobile information terminals equipped with touch sensors, typified by smartphones and tablet terminals, are widely known as devices using image display devices such as liquid crystal (LC) displays and organic EL (OLED) displays. The constituent members are adhered via a pressure-sensitive adhesive or pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition.

In recent years, with the diversification of consumer tastes, mobile information terminals are required to have a high degree of design, and mobile information terminals having curved displays and housings are becoming popular. Curved glass and curved resin glass are used in such mobile information terminals, and the adhesive used for laminating these optical members has an initial adhesive strength that exhibits a higher adhesive strength than the initial stage of lamination. Furthermore, it is required that the adhesive layer does not turn white when used in a high-temperature and high-humidity environment (wet heat whitening resistance).

For example, in Patent Document 1, "at least a dicarboxylic acid having a side chain and a polyester obtained by polycondensation of a diol, a polyether polyol, and a cross-linking agent are contained, and the weight average molecular weight of the polyester is , 5000 to 50000, the polyether polyol contains a polyether polyol having hydroxyl groups only at some terminals and/or all terminals, and the polyether polyol having hydroxyl groups only at some terminals The terpolyol has a number average molecular weight of 100 to 1500, and the polyether polyol having hydroxyl groups only at some terminals is contained in an amount of 1 to 35 parts by weight with respect to 100 parts by weight of the polyester. A polyester-based pressure-sensitive adhesive composition.” is disclosed.

Further, in Patent Document 2, "a polyester-based pressure-sensitive adhesive composition containing a polyester-based resin (A), wherein the polyester-based resin (A) comprises a structural unit derived from a polyvalent carboxylic acid (a1) and a polyol and a structural unit derived from (a2), the polyvalent carboxylic acid (a1) contains a sulfonate group-containing dicarboxylic acid (a1-1), and the sulfonate group-containing dicarboxylic acid (a1-1 ) is 0.0001 to 0.15 mmoL/g relative to the polyester resin (A).” is disclosed.

JP 2013-216875 A JP 2019-85518 A

In the pressure-sensitive adhesive composition disclosed in Patent Document 1, since a large amount of polyether polyol is contained in a polyester-based resin having a low ester bond concentration, problems remain in initial adhesive strength and optical properties.

In addition, in the pressure-sensitive adhesive composition disclosed in Patent Document 2, the polyester resin has a sulfonate group, which leaves a problem of wet heat durability, and is also unsatisfactory in terms of wet heat whitening resistance.

Therefore, under such a background, the present invention is a polyester-based adhesive that exhibits excellent initial adhesive strength that exhibits higher adhesive strength than at the initial stage of lamination, further has excellent optical properties, and has excellent wet heat whitening resistance under high temperature and high humidity. A pressure-sensitive adhesive obtained by cross-linking the pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive, and an optical disc with a pressure-sensitive adhesive layer having the pressure-sensitive adhesive layer. It is also intended to provide a component.

However, as a result of intensive research in view of such circumstances, the present inventors have found a polyester-based pressure-sensitive adhesive composition containing a polyester-based resin (A), a polyoxyalkylene polyol (B), and a hydrolysis inhibitor (C). There, by containing a specific amount of polyoxyalkylene polyol (B) with respect to the polyester resin (A), excellent initial adhesive strength that exhibits higher adhesive strength than the initial stage of lamination, and optical properties The present inventors have found that a polyester-based pressure-sensitive adhesive composition having excellent resistance to wet heat and whitening under high temperature and high humidity conditions can be obtained, and completed the present invention.

That is, the present invention provides a polyester-based pressure-sensitive adhesive composition containing a polyester-based resin (A), a polyoxyalkylene polyol (B), and a hydrolysis inhibitor (C), wherein the polyoxyalkylene polyol (B) is contained A first gist is a polyester-based pressure-sensitive adhesive composition characterized in that the amount thereof is 0.01 to 10 parts by weight with respect to 100 parts by weight of the polyester-based resin (A).

A second aspect of the present invention is a pressure-sensitive adhesive obtained by cross-linking the 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. A fourth aspect is an optical member with a pressure-sensitive adhesive layer having a layer and an optical member.

In general, in order to increase the wet heat durability of the polyester-based pressure-sensitive adhesive composition, it is conceivable to introduce a side chain structure into the polyester-based resin or reduce the ester bond concentration, but the polarity is low. The compatibility with various additives is lowered, and the transparency of the pressure-sensitive adhesive sheet is deteriorated. On the other hand, in order to improve the wet heat whitening resistance, it is conceivable to introduce a polar group such as a sulfonate group or to include a highly polar additive, but hydrolysis is accelerated because the hydrophilicity of the resin increases. As a result, the wet heat durability is inferior, and the initial adhesive strength is lowered.
In the present invention, surprisingly, by including a small amount of polyoxyalkylene polyol in the polyester resin, the initial adhesive strength and optical properties are excellent, and wet heat whitening under high temperature and high humidity is less likely to occur. We were able to achieve the purpose of

The polyester-based pressure-sensitive adhesive composition of the present invention is a polyester-based pressure-sensitive adhesive composition containing a polyester-based resin (A), a polyoxyalkylene polyol (B), and a hydrolysis inhibitor (C), wherein the polyoxyalkylene The content of the polyol (B) is 0.01 to 10 parts by weight with respect to 100 parts by weight of the polyester resin (A). Therefore, it has excellent initial adhesive strength that exhibits high adhesive strength from the initial stage of lamination, further has excellent optical properties, and has excellent effects on wet heat whitening resistance under high temperature and high humidity. is useful as an adhesive for shatterproof films for glass and resin glass.

The configuration of the present invention will be described in detail below, but these are examples of preferred embodiments.
In this specification, each numerical value that defines a numerical range for a certain matter can independently define a new numerical range together with another numerical value that defines another numerical range. For example, when there is a description of "2 to 10% by weight, preferably 4 to 8% by weight" for a certain matter, "2 to 4% by weight", "2 to 8% by weight", "4 to 10% by weight" and A numerical range of "8-10% by weight" may be defined.

The polyester-based pressure-sensitive adhesive composition of the present invention (hereinafter also simply referred to as "pressure-sensitive adhesive composition") contains a polyester-based resin (A), a polyoxyalkylene polyol (B), and a hydrolysis inhibitor (C). do.
Each constituent component used in the pressure-sensitive adhesive composition of the present invention will be described in detail below.

<Polyester resin (A)>
The polyester-based resin (A) is usually obtained by copolymerizing copolymerization components containing polyvalent carboxylic acids (a1) and polyols (a2) as constituent raw materials, and the polyester-based resin (A) is The resin composition contains a structural unit derived from polycarboxylic acids (a1) and a structural unit derived from polyol (a2).
In the present specification, 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.

[Raw material of polyester resin (A)]
[Polyvalent carboxylic acids (a1)]
Examples of the polyvalent carboxylic acid (a1) used as a constituent raw material of the polyester resin (A) include divalent carboxylic acids and trivalent or higher polyvalent carboxylic acids, which stabilize the polyester resin (A). Divalent carboxylic acids are preferably used because they can be easily obtained.

Examples of the divalent carboxylic acids include malonic acids, dimethylmalonic acids, succinic acids, glutaric acids, adipic acids, trimethyladipic acids, pimelic acids, 3-methylglutaric acids, 2,2-dimethylglutaric acids, azelaic acids, Aliphatic dicarboxylic acids such as sebacic acids, fumaric acids, 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 compounds 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;
dimer acids derived from oleic acid, linoleic acid, linolenic acid, erucic acid and the like;

Examples of the trivalent or higher polyvalent carboxylic acids include trimellitic acids, pyromellitic acids, adamantanetricarboxylic acids, and trimesic acids.
One kind selected from these polyvalent carboxylic acids (a1) can be used alone, or two or more kinds can be used in combination.

Among the above polyvalent carboxylic acids (a1), aromatic polyvalent carboxylic acids (a1-1) are preferably contained from the viewpoint of excellent cohesion. In particular, it is more preferable to contain an asymmetric aromatic dicarboxylic acid from the viewpoint of lowering the crystallinity of the polyester-based resin (A) and improving the initial adhesive strength. Asymmetric aromatic dicarboxylic acids refer to aromatic dicarboxylic acids in which the two carboxy groups attached to the aromatic ring are attached at positions that are not symmetrical with respect to the aromatic ring. Examples include phthalic acids, isophthalic acids, 1,8-naphthalenedicarboxylic acids, 2,3-naphthalenedicarboxylic acids, and 2,7-naphthalenedicarboxylic acids. Of these, isophthalic acids are particularly preferred in terms of reactivity and optical properties.

The content of such aromatic polycarboxylic acids (a1-1), particularly asymmetric aromatic dicarboxylic acids, is the total polycarboxylic acids (a1) used as constituent raw materials of the polyester resin (A) (100 mol% ), preferably 1 to 80 mol%, more preferably 3 to 70 mol%, still more preferably 5 to 60 mol%, particularly preferably 10 to 50 mol%, particularly preferably 15 to 40 in mol %. If the content is too small, there is a tendency that the cohesive force is lowered, or the resin crystallizes, making it difficult to obtain sufficient adhesion performance. If the content is too large, the glass transition temperature becomes too high, the initial adhesive strength is lowered, and there is a concern that lamination with a pressure of about finger pressure may be difficult.

Further, in the present invention, the polyvalent carboxylic acid (a1) preferably contains a straight-chain aliphatic dicarboxylic acid (a1-2) from the viewpoint of improving the initial adhesive strength. Among them, the number of carbon atoms (including the carbon of the carboxyl group; the same applies hereinafter) is preferably 4 or more, more preferably 6 to 12 aliphatic dicarboxylic acids, adipic acids, sebacic acids, azelaic acids It is more preferable to contain

The content of such straight-chain aliphatic dicarboxylic acids (a1-2) is preferably 20 to 100 mol%, more preferably 20 to 100 mol%, relative to the total (100 mol%) of the polyvalent carboxylic acids (a1). is 30 to 97 mol %, more preferably 40 to 95 mol %, particularly preferably 50 to 90 mol %, particularly preferably 60 to 85 mol %. If the content is too small, the glass transition temperature of the polyester resin (A) tends to be too high, making it difficult to obtain sufficient adhesive strength. This tends to make it difficult to obtain sufficient adhesion performance.

In the present invention, aromatic polycarboxylic acids (a1-1) and straight-chain aliphatic dicarboxylic acids (a1-2) can be used in combination as polycarboxylic acids (a1) from the viewpoint of adhesive properties. is also preferred. In that case, the content ratio (molar ratio) between the aromatic polycarboxylic acids (a1-1) and the linear aliphatic dicarboxylic acids (a1-2) is (a1-1)/(a1-2) = It is preferably 1/99 to 80/20, more preferably 3/97 to 70/30, still more preferably 5/95 to 60/40, particularly preferably 10/90 to 50/50, particularly preferably 15/85 to 40/60.

In addition, in the present invention, polyvalent carboxylic acids (a1-3) having a hydrocarbon group in the side chain can also be used because they can destroy the crystallinity of the polyester resin (A). Examples of the side chain hydrocarbon group include an alkyl group and an alkylene group, and two or more hydrocarbon groups may combine to form a cyclic structure. The number of carbon atoms in the side chain hydrocarbon group is preferably 1 to 20, more preferably 1 to 10, still more preferably 1 to 5, and particularly preferably 1 to 3. If the hydrocarbon group in the side chain has too many carbon atoms, the compatibility with the polyoxyalkylene polyol (B) and the hydrolysis property agent (C) tends to decrease.
Such polyvalent carboxylic acids (a1-3) having a hydrocarbon group in the side chain include:
Examples include dimethylmalonic acids; trimethyladipic acids; 3-methylglutaric acids; dimer acids derived from oleic acid, linoleic acid, linolenic acid, erucic acid and the like;

The content of the dicarboxylic acids (a1-3) having a hydrocarbon group in the side chain is preferably 80 mol% or less, more preferably 80 mol% or less, relative to the total (100 mol%) of the polyvalent carboxylic acids (a1). is 60 mol % or less, more preferably 40 mol % or less, particularly preferably 20 mol % or less, particularly preferably 10 mol % or less. If the content is too large, there is a tendency that the cohesion strength is lowered, and the compatibility with the polyoxyalkylene polyol (B) and the hydrolysis property agent (C) is deteriorated, resulting in a decrease in optical properties. The content of dicarboxylic acids (a1-3) having a hydrocarbon group in the side chain may be 0 mol %.

Further, in the present invention, a trivalent or higher polyvalent carboxylic acid (a1-4) can be used for the purpose of increasing the number of branch points in the polyester resin (A). Among them, it is preferable to use polyvalent carboxylic acids containing an aromatic structure and having a valence of 3 or more, for example, trimellitic acids are preferably used because gelation is relatively unlikely to occur during production. .

The content of such a trivalent or higher polyvalent carboxylic acid (a1-4) is the total polyvalent carboxylic acid (a1) (100 mol%) in that it can increase the cohesive force when a pressure-sensitive adhesive is prepared. is preferably 10 mol % or less, more preferably 0.1 to 5 mol %. If the content is too high, gelation tends to occur during the production of the polyester-based resin (A). The content of trivalent or higher polyvalent carboxylic acids (a1-4) may be 0 mol %.

[Polyol (a2)]
Examples of the polyol (a2) used as a constituent raw material of the polyester-based resin (A) 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;
Para-xylene glycol, meta-xylene glycol, ortho-xylene glycol, 1,4-phenylene glycol, ethylene oxide adducts of 1,4-phenylene glycol, bisphenol A, bisphenol B, bisphenol E, bisphenol F, bisphenol AP, bisphenol BP, bisphenol P, bisphenol PH, bisphenol S, bisphenol Z, 4,4'-dihydroxybenzophenone, bisphenol fluorene and hydrogenated products thereof, and 1 to several moles of ethylene oxide or propylene oxide are added to the hydroxyl groups of bisphenols. Aromatic diols such as obtained ethylene oxide adducts and propylene oxide adducts;
Furthermore, fatty acid esters derived from castor oil; dimer diols derived from oleic acid, linoleic acid, linolenic acid, erucic acid, etc.; glycerol monostearate; and the like.
In addition, polyoxyalkylene diols such as polyethylene glycol, polypropylene glycol, polybutylene glycol, and polytetramethylene glycol; copolymerized polyoxyalkylene diols of 3-methyltetrahydrofuran and tetrahydrofuran, and copolymerized polyoxyalkylenes of neopentyl glycol and tetrahydrofuran. Diols, polyoxyalkylene diols copolymerized with polyethylene glycol and polypropylene glycol, polyoxyalkylene diols copolymerized with polyethylene glycol and polypropylene glycol, polyoxyalkylene diols copolymerized with polyethylene glycol and polybutylene glycol, polyethylene glycol and polytetra Examples thereof include copolymerized polyoxyalkylene diols such as copolymerized polyoxyalkylene diols with methylene glycol.

Examples of trivalent or higher polyols include pentaerythritol, dipentaerythritol, tripentaerythritol, glycerin, trimethylolpropane, trimethylolethane, 1,2,4-butanetriol, 1,2,5-pentanetriol, 1,2,6-hexanetriol, 1,3,6-hexanetriol, adamantanetriol and the like.
One kind selected from these polyols (a2) can be used alone, or two or more kinds can be used in combination.

In the present invention, among the polyols (a2), an aromatic polyol (a2-1) capable of forming a structural unit derived from an aromatic structure-containing compound can also be contained from the viewpoint of excellent cohesive force. For example, para-xylene glycol, meta-xylene glycol, ortho-xylene glycol, 1,4-phenylene glycol, ethylene oxide adducts of 1,4-phenylene glycol, bisphenol A, bisphenol B, bisphenol E, bisphenol F, bisphenol AP , bisphenol BP, bisphenol P, bisphenol PH, bisphenol S, bisphenol Z, 4,4'-dihydroxybenzophenone, bisphenol fluorene and hydrogenated products thereof, and addition of 1 to several moles of ethylene oxide or propylene oxide to the hydroxyl groups of bisphenols. polyols such as ethylene oxide adducts and propylene oxide adducts obtained by Among them, ethylene oxide adducts of bisphenols are preferable because of their excellent reactivity.

The content of the aromatic polyol (a2-1) is preferably 1 to 80 mol%, more preferably 3 to 70 mol%, still more preferably 100 mol% of the total polyol (a2). is 5 to 60 mol %, particularly preferably 10 to 50 mol %, particularly preferably 15 to 40 mol %. If the content is too small, the cohesive strength tends to decrease. If the content is too large, there is a concern that the initial adhesive strength will be lowered, or the reaction time will be lengthened during the production of the polyester resin (A), resulting in a drop in production efficiency.

In addition, from the viewpoint of lowering the glass transition temperature (Tg) of the polyester-based resin (A) and improving the initial adhesive strength, it is preferable to allow the polyol (a2) to contain a linear aliphatic diol (a2-2). . More preferred are straight-chain aliphatic diols having 2 to 18 carbon atoms, and particularly preferred are ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6- hexanediol.

The content of the linear aliphatic diol (a2-2) is preferably 5 to 100 mol%, more preferably 10 to 95 mol%, relative to the total polyol (a2) (100 mol%). , more preferably 15 to 90 mol %, particularly preferably 20 to 80 mol %, particularly preferably 30 to 70 mol %. If the content is too small, the glass transition temperature tends to be too high and the initial adhesive strength is reduced, making it difficult to perform lamination with finger pressure or the like, or to make it difficult to obtain stable resin formation. . If the content is too large, the resin tends to crystallize and the initial adhesive strength tends to decrease.

Among the above polyols (a2), it is preferable to contain a diol (a2-3) having a hydrocarbon group in a side chain because it can destroy the crystallinity. Examples of the side chain hydrocarbon group include an alkyl group and an alkylene group, and two or more hydrocarbon groups may combine to form a cyclic structure. The number of carbon atoms in the side chain hydrocarbon group is preferably 1 to 20, more preferably 1 to 10, still more preferably 1 to 5, and particularly preferably 1 to 3. If the hydrocarbon group in the side chain has too many carbon atoms, the compatibility with the polyoxyalkylene polyol (B) and the hydrolysis property agent (C) tends to decrease.
Examples of the diol (a2-3) 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-propane Diol, 2-ethyl-2-isobutyl-1,3-propanediol, 1,3-butanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,6-hexanediol, etc. 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, spiroglycol, tricyclodecanedimethanol, adamantanediol, 2,2,4 alicyclic diols having a branched structure such as ,4-tetramethyl-1,3-cyclobutanediol; dimer diols derived from oleic acid, linoleic acid, linolenic acid, erucic acid and the like; Among them, aliphatic diols having a branched structure are preferred, such as 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 3-methyl-1,5- Pentanediol is particularly preferred.

The content of the diol (a2-3) having a hydrocarbon group in the side chain is preferably 5 to 95 mol%, more preferably 10 to 95 mol%, relative to the entire polyol (a2) (100 mol%). 90 mol %, more preferably 15 to 80 mol %, particularly preferably 20 to 70 mol %, particularly preferably 30 to 60 mol %. If the content is too low, the resin tends to crystallize and the initial adhesive strength tends to decrease. .

Furthermore, in the present invention, a trivalent or higher polyol (a2 -4) is also preferably used. Among trivalent or higher polyols (a2-4), trimethylolpropane, trimethylolethane, glycerin, pentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, 1,2,6 -Hexanetriol is preferred, and trimethylolpropane is particularly preferred because gels are relatively unlikely to occur.

The content of the trivalent or higher polyol (a2-4) is preferably 10 mol % or less, and 0.1 to 5 mol %, relative to the total polyol (a2) (100 mol %). is more preferable. If the content of such trivalent or higher polyol is too large, it tends to be difficult to produce the polyester resin (A).

Among the above polyols (a2), a polyoxyalkylene diol (a2-5) can also be contained from the viewpoint of excellent wet heat whitening resistance. Examples of polyoxyalkylene diols (a2-5) include bifunctional polyoxyalkylene polyols such as polyethylene glycol, polypropylene glycol, polybutylene glycol and polytetramethylene glycol; Alkylene diols, copolymerized polyoxyalkylene diols of neopentyl glycol and tetrahydrofuran, copolymerized polyoxyalkylene diols of polyethylene glycol and polypropylene glycol, copolymerized polyoxyalkylene diols of polyethylene glycol and polybutylene glycol, polyethylene glycol and poly copolymerized polyoxyalkylene diols such as copolymerized polyoxyalkylene diols with tetramethylene glycol; and the like. Among them, polyoxyalkylene diols having a straight chain structure without side chains are preferable in that they have excellent wet heat whitening resistance, do not easily cause a decrease in adhesive strength, and have excellent reworkability and adhesion reliability. Having a structural unit is more preferred, and polyethylene glycol is particularly preferred.

The content of the polyoxyalkylene diol (a2-5) is preferably 30 mol% or less, preferably 0.01 to 20 mol%, relative to the total polyol (a2) (100 mol%). more preferably 0.1 to 10 mol%, particularly preferably 0.2 to 5 mol%, particularly preferably 0.3 to 3 mol%, particularly preferably 0.5 to 1.5 is most preferred. If the content of the polyoxyalkylene diol (a2-5) is too large, the initial adhesive strength and optical properties of the polyester resin (A) tend to be lowered.

[Method for producing polyester resin (A)]
The polyester resin used in the present invention is produced by appropriately selecting the polyvalent carboxylic acid (a1) and the polyol (a2) and subjecting them to a polycondensation reaction by a known method in the presence of a catalyst.

The mixing ratio of the polycarboxylic acid (a1) and the polyol (a2) is preferably 1 to 2 equivalents of the polyol (a2) per equivalent of the polycarboxylic acid (a1), more preferably 1. .1 to 1.7 equivalents. If the blending ratio of the polyol (a2) is too low, the acid value tends to increase, making it difficult to increase the molecular weight.

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 usually used, specifically, for example, titanium-based catalysts such as tetraisopropyl titanate and tetrabutyl titanate; antimony-based catalysts such as antimony trioxide; germanium-based catalysts such as germanium dioxide; and other catalysts such as zinc acetate, manganese acetate, dibutyltin oxide, etc., and one selected from these can be used alone or in combination of two or more. Among these, antimony trioxide, tetrabutyl titanate, germanium dioxide, and zinc acetate are preferred, and tetrabutyl titanate and zinc acetate are more preferred, in view of the balance between high catalytic activity and hue.

The blending amount of the catalyst is preferably 1 to 10000 ppm, more preferably 10 to 5000 ppm, and still more preferably 20 to 3000 ppm based on the weight of all copolymerization components. If the compounding amount is too small, the polymerization reaction tends to be difficult to proceed sufficiently, and if it is too large, there is no advantage in shortening the reaction time, and side reactions tend to occur easily.

The reaction temperature during the esterification reaction is preferably 200 to 300°C, more preferably 210 to 280°C, still more preferably 220 to 260°C. If the reaction temperature is too low, the reaction tends to be difficult to proceed, and if it is too high, side reactions such as decomposition tend to occur. Moreover, the pressure during the reaction is usually normal pressure.

After the above esterification reaction is performed, a polycondensation reaction is performed.
As for the reaction conditions of the polycondensation 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., more preferably 230 to 270° C., It is preferable to gradually depressurize 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.

A polyester resin (A) is thus obtained.

[Structure of polyester resin (A)]
The polyester-based resin (A) usually contains a structural unit derived from the polycarboxylic acids (a1) and a structural unit derived from the polyol (a2). When the structural unit derived from the aromatic polycarboxylic acids (a1-1) capable of forming the structural unit derived from the aromatic structure-containing compound is contained as a structural unit derived from the polyvalent carboxylic acids (a1), the aromatic Structural units derived from polycarboxylic acids (a1-1) are preferably 1 to 80 mol%, more preferably 3 to 70 mol%, more preferably structural units derived from polycarboxylic acids (a1). 5 to 60 mol %, particularly preferably 10 to 50 mol %, particularly preferably 15 to 40 mol %. If the content is too small, the cohesive strength tends to decrease. However, if the content is too large, there is a concern that the initial adhesive strength will decrease.

When the structural unit derived from the linear aliphatic dicarboxylic acids (a1-2) is contained as a structural unit derived from the polyvalent carboxylic acids (a1), the linear aliphatic dicarboxylic acids (a1-2 ) is preferably 20 to 100 mol%, more preferably 30 to 97 mol%, still more preferably 40 to 95 mol%, particularly preferably 40 to 95 mol% of the structural units derived from the polycarboxylic acids (a1). is 50 to 90 mol %, particularly preferably 60 to 85 mol %. If the content is too small, the glass transition temperature of the polyester resin (A) tends to be too high, making it difficult to obtain sufficient adhesive strength. This tends to make it difficult to obtain sufficient adhesion performance.

When the structural unit derived from polyvalent carboxylic acids (a1-3) having a hydrocarbon group in the side chain is contained as a structural unit derived from polyvalent carboxylic acids (a1), it has a hydrocarbon group in the side chain. Structural units derived from polycarboxylic acids (a1-3) are preferably 80 mol% or less of the structural units derived from polycarboxylic acids (a1), more preferably 60 mol% or less, still more preferably 60 mol %, particularly preferably 40 mol % or less, particularly preferably 20 mol % or less, and even more preferably 10 mol % or less. If the content is too large, there is a tendency that the cohesive force is lowered and the compatibility with the polyoxyalkylene polyol (B) and the hydrolysis inhibitor (C) is lowered.

When the structural unit derived from the trivalent or higher polyvalent carboxylic acid (a1-4) is contained as a structural unit derived from the polyvalent carboxylic acid (a1), the trivalent or higher polyvalent carboxylic acid (a1-4 ) is preferably 10 mol % or less, more preferably 0.1 to 5 mol %, of the structural units derived from the polycarboxylic acids (a1). If the content is too high, gelation tends to occur during the production of the polyester-based resin (A).

Further, when a structural unit derived from the aromatic polyol (a2-1) capable of forming a structural unit derived from the aromatic structure-containing compound is contained as a structural unit derived from the polyol (a2), the aromatic polyol (a2 The structural unit derived from -1) is preferably 1 to 80 mol%, more preferably 3 to 70 mol%, still more preferably 5 to 60 mol%, and particularly preferably the structural unit derived from the polyol (a2). 10 to 50 mol %, particularly preferably 15 to 40 mol %. If the content is too small, the cohesive strength tends to decrease. If the content is too large, there is a concern that the initial adhesive strength will be lowered, or the reaction time will be lengthened during the production of the polyester resin (A), resulting in a drop in production efficiency.

When the structural unit derived from the linear aliphatic diol (a2-2) is contained as a structural unit derived from the polyol (a2), the structural unit derived from the linear aliphatic diol (a2-2) Is preferably 5 to 100 mol% of the structural units derived from the polyol (a2), more preferably 10 to 95 mol%, still more preferably 15 to 90 mol%, particularly preferably 20 to 80 mol%, especially preferably 30 to 70 mol %. If the content is too small, the reaction time in the production of the polyester-based resin (A) will be prolonged, and the production efficiency tends to be lowered. If the content is too large, the polyester resin (A) will crystallize, and there is a concern that the initial adhesive strength of the adhesive will decrease.

When the structural unit derived from the diol (a2-3) having a hydrocarbon group in the side chain is contained as a structural unit derived from the polyol (a2), the diol (a2-3) having a hydrocarbon group in the side chain The derived structural unit is preferably 5 to 95 mol% of the structural unit derived from the polyol (a2), more preferably 10 to 90 mol%, still more preferably 15 to 80 mol%, particularly preferably 20 to 70 mol %, particularly preferably 30 to 60 mol %. If the content is too small, the polyester resin (A) will crystallize and the initial adhesive strength of the adhesive tends to decrease. , the manufacturing efficiency tends to decrease.

Further, when the structural unit derived from the trivalent or higher polyol (a2-4) is contained as a structural unit derived from the polyol (a2), the structural unit derived from the trivalent or higher polyol (a2-4) is It is preferably 10 mol % or less, more preferably 0.1 to 5 mol % of the structural units derived from the polyol (a2). If the content is too large, the polyester resin (A) tends to gel during production, making production difficult.

Here, the structural unit ratio (composition ratio) derived from each component of the polyester-based resin (A) can be obtained by, for example, NMR.

[Physical properties of polyester resin (A)]
The polyester-based resin (A) described above preferably has the following physical properties.

The glass transition temperature (Tg) of the polyester resin (A) is preferably -80 to 10°C, more preferably -70 to 0°C, and still more preferably -65 to -10°C, from the viewpoint of adhesive properties. , particularly preferably -60 to -15°C, particularly preferably -55 to -20°C, and even more preferably -50 to -30°C. If the glass transition temperature (Tg) is too high, the flexibility is lost, the initial adhesive strength is reduced, and there is a tendency for the adhesive strength to be difficult to exert even when pressure such as finger pressure is applied. tends to decrease.

Here, the glass transition temperature (Tg) of the polyester resin (A) 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.

The number average molecular weight (Mn) of the polyester resin (A) is generally 1,000 to 100,000 from the viewpoint of the cohesive strength of the adhesive. It is preferably 2,000 to 80,000, more preferably 4,000 to 50,000, even more preferably 6,000 to 40,000, particularly preferably 8,000 to 30,000, and most preferably 10,000 to 20,000. If the number average molecular weight is too small, sufficient cohesive strength as an adhesive cannot be obtained, and the heat resistance and mechanical strength tend to decrease. On the other hand, if the number average molecular weight is too large, the adhesiveness to the substrate tends to decrease.

The weight-average molecular weight (Mw) of the polyester-based resin (A) is usually 5,000 to 300,000 from the viewpoint of cohesion of the adhesive. It is preferably 8,000 to 200,000, more preferably 10,000 to 180,000, still more preferably 20,000 to 160,000, particularly preferably 30,000 to 140,000, and most preferably 40,000 to 120,000. If the weight-average molecular weight is too small, sufficient cohesive strength as an adhesive cannot be obtained, and the heat resistance and mechanical strength tend to decrease. On the other hand, if the weight average molecular weight is too large, the adhesiveness to the substrate tends to be lowered.

The number average content (Mn) and weight average molecular weight (Mw) of the polyester resin (A) are the average molecular weights in terms of standard polystyrene molecular weights, and a column : Measured by using four in series, one ACQUITY APC XT 450, one ACQUITY APC XT 200, and two ACQUITY APC XT 45.

The hydroxyl value of the polyester resin (A) is preferably 1 to 50 mgKOH/g, more preferably 2 to 30 mgKOH/g, still more preferably 3 to 20 mgKOH/g, particularly preferably 4 to 15 mgKOH/g. . If the hydroxyl value is too high, the efficiency of cross-linking with the cross-linking agent (D) described later tends to decrease, and if it is too low, the cohesive force tends to decrease.

The acid value of the polyester resin (A) is preferably 10 mgKOH/g or less, more preferably 5 mgKOH/g or less, still more preferably 3 mgKOH/g or less, particularly preferably 1 mgKOH/g or less, particularly preferably 0 .5 mg KOH/g or less. If the acid value is too high, hydrolysis is likely to proceed, and wet heat durability, adhesive strength, and wet heat whitening resistance tend to decrease. tend to corrode metals.

Here, the above hydroxyl value and acid value are obtained by neutralization titration based on JIS K 0070.

The ester bond concentration of the polyester resin (A) is usually 1 to 15 mmol/g, preferably 1.5 to 14 mmol/g, more preferably 2 to 13 mmol/g, still more preferably 3 to 12 mmol/g, Particularly preferably 3.5 to 11 mmol/g, particularly preferably 4 to 10.5 mmol/g, still more preferably 5 to 10 mmol/g, even more preferably 6 to 9.5 mmol/g, most preferably 7 to 9 mmol/g. If the ester bond concentration is too low, the compatibility with the polyoxyalkylene polyol (B) and the hydrolysis inhibitor (C) tends to be poor and the optical properties tend to deteriorate. tend to decline.
The definition and measuring method of the ester bond concentration of the polyester resin (A) are as follows.
The ester bond concentration (mmol/g) means the number of moles of ester bonds in 1 g of the polyester resin (A), and is obtained, for example, by a calculated value from the charged amount. This calculation method is a value obtained by dividing the number of moles of the smaller of the charged amounts of the polyhydric carboxylic acid and the polyhydric alcohol by the total weight of the resin, and an example of the calculation formula is shown below.
When the polyhydric carboxylic acid and the polyhydric alcohol are charged in the same molar amount, either of the following formulas may be used.
Also, when using a monomer having both a carboxy group and a hydroxyl group, or when producing a polyester from caprolactone or the like, the calculation method will be changed as appropriate.

(When polyhydric carboxylic acids are less than polyhydric alcohols)
Ester group concentration (mmol/g)=[(A1/a1×m1+A2/a2×m2+A3/a3×m3 . . . )/Z]×1000
A: Charge amount (g) of polyvalent carboxylic acid
a: molecular weight of polyvalent carboxylic acid m: number of carboxylic acid groups per molecule of polyvalent carboxylic acid Z: finished weight (g)

(When polyhydric alcohols are less than polyhydric carboxylic acids)
Ester group concentration (mmol/g) = [(B1/b1 x n1 + B2/b2 x n2 + B3/b3 x n3...)/Z] x 1000
B: Charged amount of polyhydric alcohol (g)
b: molecular weight of polyhydric alcohol n: number of hydroxyl groups per molecule of polyhydric alcohol Z: finished weight (g)

The ester bond concentration can also be measured by a known method using NMR or the like.

<Polyoxyalkylene polyol (B)>
The polyoxyalkylene polyol (B) imparts wet heat whitening resistance to the polyester pressure-sensitive adhesive composition, and by adding a small amount, the effect of excellent wet heat resistance without impairing the initial adhesive strength and optical properties. can have In addition, the polyoxyalkylene polyol (B) is not contained as the polyoxyalkylene diol (a2-5) which is a constituent raw material of the polyester resin (A), and is a constituent component different from the polyester resin (A). By containing as, it becomes excellent in wet heat whitening resistance without impairing the initial adhesive strength, and excellent in optical properties without being affected by the heat history in the production of the polyester resin.

[Type of polyoxyalkylene polyol (B)]
The polyoxyalkylene polyol (B) is not particularly limited, and conventionally known ones can be used.
For example, bifunctional polyoxyalkylene polyols such as polyethylene glycol, polypropylene glycol, polybutylene glycol, and polytetramethylene glycol; trifunctional polyoxyalkylene polyols such as trimethylolpropane tripolyoxyethylene ether; pentaerythritol polyoxyethylene ether, etc. tetrafunctional polyoxyalkylene polyol; copolymerized polyoxyalkylene polyol of 3-methyltetrahydrofuran and tetrahydrofuran, copolymerized polyoxyalkylene polyol of neopentyl glycol and tetrahydrofuran, copolymerized polyoxyalkylene of polyethylene glycol and polypropylene glycol Copolymerized polyoxyalkylene polyols such as polyols, copolymerized polyoxyalkylene polyols of polyethylene glycol and polybutylene glycol, and copolymerized polyoxyalkylene polyols of polyethylene glycol and polytetramethylene glycol, and the like can be mentioned. Among them, a polyoxyalkylene polyol having a linear structure having no side chain is preferable, and it is more preferable to have a structural unit derived from ethylene oxide, because it is excellent in resistance to wet heat whitening and does not easily cause a decrease in adhesive strength. Particularly preferred is polyethylene glycol.
One kind selected from these can be used alone, or two or more kinds can be used in combination.

Further, as the polyoxyalkylene polyol (B), a polyoxyalkylene polyol having some terminal hydroxyl groups modified may be used. For example, aliphatic hydrocarbon groups such as methyl group, ethyl group, allyl group, propyl group, butyl group and 2-ethylhexyl group; aromatic hydrocarbon groups such as phenyl group, methylphenyl group, nonylphenyl group and benzyl group A portion of the terminal hydroxyl groups of the polyoxyalkylene polyol (B) may be modified with a group to eliminate reactivity. However, when all the terminal hydroxyl groups are modified, the reactivity is completely lost, so the cross-linking reaction with the polyester resin (A) becomes impossible, and the polyoxyalkylene polyol (B) bleeds out to the adhesive surface. and the initial adhesive strength tends to decrease.

[Physical properties of polyoxyalkylene polyol (B)]
The number average molecular weight (Mn) of the polyoxyalkylene polyol (B) is preferably 450 to 20,000, more preferably 500 to 10,000, even more preferably 550 to 6,000, particularly preferably 750. to 4000, particularly preferably 1000-3000, most preferably 1500-2500. If the number average molecular weight of the polyoxyalkylene polyol (B) is too small, the wet heat whitening resistance tends to decrease. There is a tendency that the compatibility of the resin is poor and the optical properties are deteriorated.

The content of the polyoxyalkylene polyol (B) is preferably 0.01 to 10 parts by weight, more preferably 0.1 to 8 parts by weight, and still more preferably 100 parts by weight of the polyester resin (A). 0.2 to 6 parts by weight, particularly preferably 0.3 to 5 parts by weight, particularly preferably 0.4 to 4 parts by weight, most preferably 0.5 to 3 parts by weight. If the content of the polyoxyalkylene polyol (B) is too small, the wet heat whitening resistance tends to be lowered, and if the content is too large, the initial adhesive strength and optical properties tend to be lowered.

<Hydrolysis inhibitor (C)>
The pressure-sensitive adhesive composition of the present invention preferably further contains a hydrolysis inhibitor (C). Containing such a hydrolysis inhibitor (C) can further ensure long-term durability of the polyester-based pressure-sensitive adhesive composition.

As the hydrolysis inhibitor (C), conventionally known ones can be used. Examples thereof include compounds that react with and bind to the terminal carboxy groups of the polyester resin (A), and specific examples include compounds containing functional groups such as carbodiimide groups, epoxy groups, and oxazoline groups. be done. As the hydrolysis inhibitor (C), one selected from these can be used alone, or two or more thereof can be used in combination. Among them, a carbodiimide group-containing compound and an oxazoline group-containing compound are preferable because they are highly effective in eliminating the catalytic activity of protons derived from carboxylic acid terminal groups. That is, it is preferable to use at least one of the carbodiimide group-containing compound and the oxazoline group-containing compound.

Examples of the carbodiimide group-containing compound include known carbodiimide compounds having one or more carbodiimide groups (-N=C=N-) in the molecule. It is preferable that the compound is a polyvalent carbodiimide-based compound, particularly a compound containing 3 or more, further 5 or more, particularly 7 or more carbodiimide groups in the molecule. The number of carbodiimide groups in the molecule of the polyvalent carbodiimide compound is 50 or less. If the number of carbodiimide groups is too large, there is concern that the compatibility with the polyester-based resin (A) will decrease.

As the carbodiimide group-containing compound, 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.

Such high-molecular-weight polycarbodiimide may be synthesized or a commercially available product may be used. When synthesizing a high-molecular-weight polycarbodiimide, for example, the following diisocyanates may be subjected 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 one selected from these can be used alone or in combination of two or more.

Furthermore, the high-molecular-weight polycarbodiimide whose terminal isocyanate groups are blocked with a blocking agent is preferable from the viewpoint of storage stability. Examples of blocking agents include compounds having active hydrogens that react with isocyanate groups, or compounds having isocyanate groups. Examples include compounds having one substituent selected from a carboxy group, an amino group and an isocyanate group (eg, monoalcohols, monocarboxylic acids, monoamines and monoisocyanates).

The carbodiimide equivalent of the carbodiimide group-containing compound is preferably 50 to 10,000, more preferably 100 to 1,000, still more preferably 150 to 500.
The carbodiimide equivalent is the chemical formula weight per carbodiimide group.

Moreover, the said carbodiimide group containing compound may use a commercial item. 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-04PF", "V-05", "V-07", "V-09", "V-09GB" and "H-01" are polyester resins It is preferable in terms of excellent compatibility with (A).

Examples of the epoxy group-containing compound include glycidyl ester compounds and glycidyl ether compounds. One kind selected from these can be used alone, or two or more kinds can be used in combination.
Glycidyl ester compounds include, for example, benzoic acid glycidyl ester, t-Bu-benzoic acid glycidyl ester, p-toluic acid glycidyl ester, cyclohexanecarboxylic acid glycidyl ester, pelargonic acid glycidyl ester, stearic acid glycyl ester, lauric acid glycidyl ester, Glycidyl palmitate, glycidyl behenate, glycidyl versatate, glycidyl oleate, glycidyl linoleate, glycidyl linolenate, glycidyl behenoleate, glycidyl stearate, diglycidyl terephthalate, diisophthalate Glycidyl ester, diglycidyl phthalate, diglycidyl naphthalene dicarboxylate, diglycidyl methyl terephthalate, diglycidyl hexahydrophthalate, diglycidyl tetrahydrophthalate, diglycidyl cyclohexanedicarboxylate, diglycidyl adipate , diglycidyl succinate, diglycidyl sebacate, diglycidyl dodecanedioate, diglycidyl octadecanedicarboxylate, triglycidyl trimellitate, tetraglycidyl pyromellitate, etc., and selected from among these. can be used alone or in combination of two or more.

Examples of glycidyl ether compounds include phenylglycidyl ether, o-phenylglycidyl ether, 1,4-bis(β,γ-epoxypropoxy)butane, and 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; 2,2-bis-(4-hydroxyphenyl)methane Bisglycidyl polyether obtained by reaction of bisphenol and epichlorohydrin such as bisglycidyl polyether and the like can be mentioned, and one selected from these can be used alone or two or more can be used in combination.

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), etc., and one selected from these can be used alone or two or more of them can be used in combination.

As these hydrolysis inhibitors (C), those having low volatility are preferred. Therefore, it is preferable to use one having a high number average molecular weight, usually 300 to 10,000, preferably 1,000 to 5,000.
As the hydrolysis inhibitor (C), 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 (C) is preferably 500 or more, more preferably 2000 or more, even more preferably 3000 or more. In addition, the upper limit of the weight average molecular weight is usually 50,000.
If the molecular weight of the hydrolysis inhibitor (C) is too small, the hydrolysis resistance tends to decrease. If the molecular weight is too large, the compatibility with the polyester-based resin (A) may deteriorate and the optical properties may deteriorate.

The content of the hydrolysis inhibitor (C) is preferably 0.01 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, with respect to 100 parts by weight of the polyester resin (A). , more preferably 0.3 to 3 parts by weight, particularly preferably 0.5 to 2 parts by weight. If the content is too high, the compatibility with the polyester-based resin (A) is poor, and the optical properties tend to deteriorate, and the initial adhesive strength tends to decrease. tends to be difficult.

Moreover, it is preferable to optimize the content of the hydrolysis inhibitor (C) according to the acid value of the polyester resin (A).
For example, the total number of moles (Y) of the functional groups of the hydrolysis inhibitor (C) in the pressure-sensitive adhesive composition with respect to the total number of moles (X) of the acidic functional groups of the polyester resin (A) in the pressure-sensitive adhesive composition is preferably 0.5 ≤ (Y) / (X), more preferably 1 ≤ (Y) / (X) ≤ 1000, more preferably 1 .5≤(Y)/(X)≤100, particularly preferably 2≤(Y)/(X)≤50, particularly preferably 2.5≤(Y)/(X)≤30, most preferably 3 ≦(Y)/(X)≦15.
If the molar ratio of (Y) to (X) is too low, the wet heat resistance tends to decrease. If the molar ratio of (Y) to (X) is too high, the compatibility with the polyester-based resin (A) may be reduced, resulting in poor optical properties or reduced initial adhesive strength.

<Crosslinking agent (D)>
The pressure-sensitive adhesive composition of the present invention preferably further contains a cross-linking agent (D).
Examples of the cross-linking agent (D) include compounds having a functional group that reacts with at least one of the hydroxyl group and the carboxy group contained in the polyester resin (A). Examples include polyisocyanate compounds, polyepoxy compounds, and the like. is. 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. Also included are adducts of these polyisocyanates and polyol compounds such as trimethylolpropane, and burettes and isocyanurates of these polyisocyanate compounds. The above polyisocyanate-based compound may also be one in which the isocyanate portion is blocked with phenol, lactam, or the like. One type selected from these cross-linking agents (D) can be used alone, or two or more types can be used in combination.

The content of the cross-linking agent (D) is preferably 0.01 to 15 parts by weight, more preferably 0.1 to 10 parts by weight, with respect to 100 parts by weight of the polyester resin (A). It is preferably 0.3 to 8 parts by weight, particularly preferably 0.5 to 5 parts by weight, particularly preferably 1.0 to 3.0 parts by weight. If the content is too high, the adhesive strength of the polyester resin (A) tends to decrease and the wet heat whitening resistance tends to decrease. .

The content of the cross-linking agent (D) can be appropriately set according to the amounts of hydroxyl groups and carboxy groups contained in the polyester resin (A). For example, the reactive group contained in the cross-linking agent (D) is 0.2 to 10 equivalents with respect to 1 equivalent of at least one of the hydroxyl group and the carboxy group contained in the polyester resin (A). It preferably contains (D), more preferably 0.5 to 5 equivalents, still more preferably 0.5 to 3 equivalents.
If the number of equivalents of the reactive groups contained in the cross-linking agent (D) 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 (A) and the polyoxyalkylene polyol (B) and the cross-linking agent (D), the functional group that reacts with these components (A), (B) and (D) is used. Organic solvents such as esters such as ethyl acetate and butyl acetate; ketones such as methyl ethyl ketone and methyl isobutyl ketone; aromatics such as toluene and xylene; One kind selected from these organic solvents can be used alone, or two or more kinds can be used in combination.

<Urethane catalyst (E)>
The pressure-sensitive adhesive composition of the present invention preferably further contains a urethanization catalyst (E).
As the urethanization catalyst (E), for example, an organometallic compound, a tertiary amine compound, or the like can be used. One kind selected from these can be used alone, or two or more kinds can be used in combination.

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 (E), organometallic compounds are preferred, zirconium compounds are more preferred, and zirconium acetylacetonate is even more preferred, in terms of reaction rate and pot life of the adhesive layer.

The content of the urethanization catalyst (E) is preferably 0.001 to 1 part by weight, more preferably 0.005 to 0.5 part by weight, with respect to 100 parts by weight of the polyester resin (A). parts, more preferably 0.01 to 0.1 parts by weight, and particularly preferably 0.02 to 0.05 parts by weight. If the content is too high, the resistance to moist heat tends to decrease.

[Catalytic action inhibitor]
In the pressure-sensitive adhesive composition of the present invention, it is preferable to incorporate a catalytic action inhibitor into the urethanization catalyst (E) from the viewpoint of extending the pot life and improving 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, benzoylacetone, and the like. β-diketone; and the like. These are keto-enol tautomeric compounds, and by protecting the urethanization catalyst (E), they reduce the catalytic activity of the urethanization catalyst (E) in a solution state, resulting in the pressure-sensitive adhesive composition after blending. 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. In addition, one selected from these catalytic action inhibitors can be used alone, or two or more thereof can be used in combination.

The compounding ratio (weight ratio) of the catalytic action inhibitor and the urethanization catalyst (E) is preferably in the range of catalytic action inhibitor: urethanization catalyst (E) = 0.001: 1 to 15: 1, and more It is preferably 0.005:1 to 13:1, more 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 (E), the pot life tends to be short and the coatability tends to decrease. .

<Other additives>
In the adhesive composition of the present invention, in addition to the polyester resin (A), polyoxyalkylene polyol (B), hydrolysis inhibitor (C), cross-linking agent (D), urethanization catalyst (E), etc. Also, other additives can be blended within a range that does not impair the effects of the present invention. Examples of such additives include antioxidants such as hindered phenols, plasticizers, ultraviolet absorbers, silane coupling agents, antistatic agents, additives such as tackifiers; other inorganic or organic fillers. , metal powders, powders such as pigments, and particulate additives, and one selected from these may be used alone or two or more may be used in combination.

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

Such an adhesive composition is prepared, for example, by preparing the polyester resin (A), the polyoxyalkylene polyol (B), the hydrolysis inhibitor (C) and necessary optional components, and the polyester resin (A). It can be prepared by blending and dispersing during the production of or by blending and dispersing in a solution of the polyester resin (A) dissolved in an organic solvent.

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). is applied and dried to form an adhesive layer. A pressure-sensitive adhesive sheet is shown below as an example of the application of the pressure-sensitive adhesive according to the present invention.

<Adhesive sheet>
The pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer containing the above polyester-based pressure-sensitive adhesive, and the pressure-sensitive adhesive sheet has the pressure-sensitive adhesive layer on at least one side of the substrate, that is, on one side and/or both sides of the substrate. or a substrate-less double-faced pressure-sensitive adhesive sheet that does not have a substrate. Moreover, the pressure-sensitive adhesive sheet of the present invention is particularly suitable as a pressure-sensitive adhesive sheet for optical members used for bonding optical members.
In this specification, the term "sheet" includes "film" and "tape".

The pressure-sensitive 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. An adhesive layer is formed, a release sheet is attached to its surface (the surface opposite to the surface in contact with the base material), and if necessary, it is cured to have a base material and an adhesive layer, and the adhesive layer has a base material and an adhesive layer. A pressure-sensitive adhesive sheet of the present invention provided on at least one side of the substrate is obtained.

Alternatively, the pressure-sensitive adhesive composition is applied onto a release sheet and dried to form a pressure-sensitive adhesive layer, and the surface thereof (the surface opposite to the surface in contact with the release sheet) is laminated with a substrate, The pressure-sensitive adhesive sheet of the present invention can also be obtained by curing as necessary.

In addition, by forming a pressure-sensitive adhesive layer on a release sheet and laminating the release sheet and another release sheet on the surface thereof (the surface opposite to the surface in contact with the release sheet), a substrate without a base material can be obtained. A material-less type substrate-less double-sided PSA sheet can be produced.

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; Polyurethane: Synthetic resin sheet made of cycloolefin polymer, etc.; Examples include woven fabrics and non-woven fabrics made of.
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, polyimide, and polyurethane are particularly preferable, and polyethylene terephthalate is particularly preferable in that it has excellent adhesiveness to the pressure-sensitive adhesive.

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 silicone-based release sheet as the release sheet.

The thickness of the substrate is, for example, preferably 1 to 1000 μm, more preferably 2 to 500 μm, still more 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 can be used.

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

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 can be carried out under conditions such as up to 14 days, 40° C. for 1 to 10 days, and the like.

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 1 to 500 μm, more preferably 5 to 300 μm, still more preferably 10 to 200 μm. If the thickness of the pressure-sensitive adhesive layer is too thin, the adhesive strength tends to decrease. There is 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). required by

The gel fraction of the pressure-sensitive adhesive layer is preferably 5% by weight or more, more preferably 10 to 95% by weight, still more preferably 20 to 90% by weight, particularly preferably 20% to 90% by weight, from the viewpoint of durability and adhesive strength. is 30 to 85% by weight, particularly preferably 40 to 80%. If the gel fraction is too low, durability tends to decrease due to a decrease in cohesive strength. In addition, if the gel fraction is too high, there is a concern that the adhesive strength 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, an adhesive sheet (not provided with a separator) in which an adhesive layer is formed on a polymer sheet (for example, PET film, etc.) serving as a base material is wrapped with 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 addition, in a pressure-sensitive adhesive sheet having an adhesive layer formed on one side of a base material, the surface of the base material opposite to the pressure-sensitive adhesive layer is subjected to a release treatment so that the pressure-sensitive adhesive layer is brought into contact with the release-treated surface. It is also possible to protect the pressure-sensitive adhesive layer.

<Optical member with adhesive layer>
In addition, the pressure-sensitive adhesive of the present invention can be used for bonding various members, but it is particularly suitable for bonding optical members because it has excellent optical properties and excellent wet heat whitening resistance under high temperature and high humidity. It is preferable to use it as a pressure-sensitive adhesive for 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 of the present invention having the pressure-sensitive adhesive layer and the optical member can be prepared.

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 silicone-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. "Parts" and "%" in the examples are by weight unless otherwise specified.
Further, the glass transition temperature, number average molecular weight, weight average molecular weight, acid value, hydroxyl value and ester bond concentration in the following examples were measured according to the methods described above.

Each component was prepared as follows.

[Production of polyester resin]
The mol % of each component which is a polyvalent carboxylic acid described in the following production examples indicates a molar ratio when the total amount of the polyvalent carboxylic acids is 100 mol %.
Moreover, the mol% of each component which is a polyol described in the following production examples indicates the molar ratio when the total amount of the polyol is 100 mol%.

[Polyester resin (A-1]
In a reaction vessel equipped with a heating device, a thermometer, a stirrer, a rectifying column, a nitrogen inlet tube, and a vacuum device, 96 parts of isophthalic acid as polyvalent carboxylic acids (a1), 468 parts of sebacic acid and 468 parts of sebacic acid as polyol (a2) 271 parts of neopentyl glycol, 130 parts of 1,4-butanediol, 3 parts of 1,6-hexanediol, 5 parts of trimethylolpropane, and 0.1 part of zinc acetate as a catalyst were charged, and the temperature was gradually increased to 250°C. The mixture was raised and an esterification reaction was carried out over 4 hours. Thereafter, 0.05 part of tetrabutyl titanate was charged as a catalyst, the internal temperature was raised to 260° C. and the pressure was reduced to 1.33 hPa, and a polycondensation reaction was carried out over 3 hours to obtain a polyester resin (A-1).
The resulting polyester resin (A-1) had a glass transition temperature (Tg) of −48° C., a number average molecular weight (Mn) of 11,000, and a weight average molecular weight (Mw) of 77,000. Other physical properties were as shown in Table 2 below.
In addition, the ratio of finished components was as follows: isophthalic acid/sebacic acid = 20 mol%/80 mol% as polyvalent carboxylic acid (a1), and neopentyl glycol/1,4-butanediol/1,6-hexane as polyol (a2). Diol/trimethylolpropane = 58.5 mol%/34 mol%/6.2 mol%/1.3 mol%.

Table 1 shows the resin composition (structural units derived from components) and Table 2 shows various physical properties of the polyester resin (A-1) obtained above. Each abbreviation in Table 1 is as follows.
"IPA": isophthalic acid (a1-1)
"SebA": sebacic acid (a1-2)
"1,4BG": 1,4-butanediol (a2-2)
"1,6HG": 1,6-hexanediol (a2-2)
"NPG": neopentyl glycol (a2-3)
"TMP": trimethylolpropane (a2-4)

[Polyoxyalkylene polyol (B)]
(B-1) Polyethylene glycol (manufactured by Sanyo Kasei Co., Ltd., "PEG600") number average molecular weight 600
(B-2) Polyethylene glycol (manufactured by Sanyo Kasei Co., Ltd., "PEG1000") number average molecular weight 1000
(B-3) Polyethylene glycol (manufactured by Sanyo Kasei Co., Ltd., "PEG2000") number average molecular weight 2000

[Hydrolysis inhibitor (C)]
(C-1): Polyvalent carbodiimide compound (manufactured by Nisshinbo Chemical Co., Ltd., "Carbodilite (registered trademark) V-09GB")

[Crosslinking agent (D)]
(D-1): Trimethylolpropane/tolylene diisocyanate adduct (manufactured by Tosoh Corporation, "Coronate L55E")

[Urethane catalyst (E)]
(E-1): A zirconium-based compound diluted with acetylacetone to a solid concentration of 1% (manufactured by Matsumoto Fine Chemicals Co., Ltd., "Orgatics ZC-150")

(Example 1)
The polyester resin (A-1) obtained above was diluted with ethyl acetate to a solid content concentration of 50%, and this polyester resin (A-1) (100 parts as solid content) was added with a polyoxyalkylene polyol ( B-1) 2 parts, hydrolysis inhibitor (C-1) 1 part, crosslinking agent (D-1) 3.0 parts (solid content), urethanization catalyst (E-1) 0.02 parts (solid content ) were blended, stirred and mixed to obtain an adhesive composition.

(Example 2)
In Example 1, 2 parts of the polyoxyalkylene polyol (B-1) was changed to 1 part of (B-2), and 3.0 parts of the cross-linking agent (D-1) was changed to 2.2 parts. A pressure-sensitive adhesive composition was obtained in the same manner as in Example 1.

(Example 3)
In Example 1, 2 parts of the polyoxyalkylene polyol (B-1) was changed to 1 part of (B-3), and the amount of the cross-linking agent (D-1) was changed from 3.0 parts to 2.0 parts. A pressure-sensitive adhesive composition was obtained in the same manner as in Example 1, except for the above.

(Comparative example 1)
In Example 1, the procedure was the same as in Example 1, except that the polyoxyalkylene polyol (B-1) was not blended and the amount of the cross-linking agent (D-1) was changed from 3.0 parts to 1.8 parts. to obtain an adhesive composition.

(Comparative example 2)
In Example 1, 2 parts of the polyoxyalkylene polyol (B-1) was changed to 15 parts of (B-3), and the amount of the cross-linking agent (D-1) was changed from 3.0 parts to 12.0 parts. A pressure-sensitive adhesive composition was obtained in the same manner as in Example 1, except for the above.

Using the adhesive compositions obtained in the above examples and comparative examples, adhesive sheets were produced and evaluated as follows. The results are summarized in Tables 3 and 4.

<Preparation of pressure-sensitive adhesive sheet with single-sided release film>
The polyester pressure-sensitive adhesive compositions obtained in Examples 1 to 3 and Comparative Examples 1 and 2 were applied to a 100 μm thick PET film (manufactured by Toray Industries, Inc., “Lumirror T100”) using an applicator. C. for 4 minutes to obtain an adhesive sheet with a PET film having an adhesive composition layer thickness of 50 μm.
Then, the surface of the adhesive composition layer of the obtained PET film-attached adhesive sheet was covered with a 38 μm thick PET release film (manufactured by Mitsui Chemicals Tohcello, SP-PET-01-BU) and kept at 40° C. for 4 days. An aging treatment was performed to obtain a pressure-sensitive adhesive sheet with a release film on one side.

[Gel fraction]
The adhesive sheet obtained above was wrapped in a 200-mesh SUS wire mesh and immersed in toluene at 23°C for 24 hours. The weight of each component was measured, and the percentage was calculated according to the following formula to obtain the gel fraction (%). However, the weight of the substrate was subtracted.
Weight of undissolved adhesive component remaining in wire mesh after immersion/weight of adhesive component before immersion x 100 (%)

(Adhesive sheet evaluation)
"Adhesion evaluation"
[Initial adhesive strength (adhesive strength)]
The pressure-sensitive adhesive sheet with a single-sided release film obtained above was cut into a size of 25 mm × 200 mm under an environment of 23 ° C. and 50% RH, then the release film was peeled off, and the pressure-sensitive adhesive layer side was polycarbonate (PC ), and non-alkali glass (manufactured by Corning, Eagle XG), pressure pasted by reciprocating a 2 kg roller twice, left for 30 minutes in the same atmosphere, Autograph (manufactured by Shimadzu Corporation, "Autograph AG-X 50 N") was used to measure the 180 degree peel rate (N/25 mm) at a peel rate of 300 mm/min. Evaluation criteria are as follows.

(Evaluation criteria: versus polycarbonate (PC))
◎: Greater than 15N/25mm ○: Greater than 10N/25mm and 15N/25mm or less △: Greater than 3N/25mm and 10N/25mm or less ×: 3N/25mm or less

(Evaluation criteria: vs. alkali-free glass)
◎: 5 N/25 mm or more ○: 3 N/25 mm or more, less than 5 N/25 mm △: 1 N/25 mm or more, less than 3 N/25 mm ×: less than 1 N/25 mm

"Optical Characteristic Evaluation"
[Initial haze]
The pressure-sensitive adhesive sheet with a single-sided release film obtained above was cut into a size of 30 mm × 50 mm in an environment of 23 ° C. and 50% RH, then the release film was peeled off, and the pressure-sensitive adhesive layer side was covered with non-alkali glass. (manufactured by Corning, Eagle XG) was pressure-bonded by reciprocating a 2-kg roller twice, and pressure-bonded by autoclave treatment (50°C, 0.5 MPa, 20 minutes) to form a PET film/adhesive layer/non-alkali glass plate. A test piece having
The haze of the test piece under the environment of 23° C. and 50% RH was measured using HAZE MATER NDH2000 (manufactured by Nippon Denshoku Industries Co., Ltd.).

(Evaluation criteria)
◎ ... 3.0% or less ○ ... 3.0% or less, 5.0% or less △ ... 5.0% or more, 10.0% or less × ... 10.0% or less big

[Haze after moist heat test]
The test piece used in the initial haze measurement was subjected to a wet heat test at 85°C x 85% RH x 100 hours, and the haze 10 minutes after removal was evaluated in the same manner as in the initial haze measurement.

[Haze displacement (wet heat whitening resistance)]
The haze displacement before and after the wet heat test was evaluated according to the following criteria.
Haze displacement (%) = Haze value after wet heat test (%) - Initial haze value (%)
◎...Haze displacement less than 2% ○...Haze displacement 2% or more and less than 5% △...Haze displacement 5% or more and less than 10% ×...Haze displacement 10% or more

From the results shown in Tables 3 and 4, it can be seen that the pressure-sensitive adhesive sheets obtained from the pressure-sensitive adhesive compositions of Examples 1 to 3 are excellent in both initial adhesive strength and wet heat whitening resistance.
On the other hand, the pressure-sensitive adhesive sheet obtained from the pressure-sensitive adhesive composition of Comparative Example 1 was excellent in initial adhesive strength, but was inferior in wet heat whitening resistance because it did not contain the polyoxyalkylene polyol (B).
In Comparative Example 2, since the content of the polyoxyalkylene polyol (B) was large, the initial haze and the haze after the wet heat test were inferior.
Also from this, it contains a polyester resin (A), a polyoxyalkylene polyol (B), and a hydrolysis inhibitor (C), and the polyoxyalkylene polyol (B) is the polyester resin (A) 100 parts by weight Therefore, it can be seen that the adhesive composition containing 0.01 to 10 parts by weight is excellent in adhesive properties.

The polyester-based pressure-sensitive adhesive composition of the present invention is excellent in initial adhesive strength, optical properties, and wet heat whitening resistance. can be used as a shatterproof film for glass or resin glass.

Claims (14)

A polyester-based pressure-sensitive adhesive composition containing a polyester-based resin (A), a polyoxyalkylene polyol (B), and a hydrolysis inhibitor (C),
A polyester pressure-sensitive adhesive composition characterized in that the content of the polyoxyalkylene polyol (B) is 0.01 to 10 parts by weight with respect to 100 parts by weight of the polyester resin (A). 2. The polyester-based pressure-sensitive adhesive composition according to claim 1, wherein the polyester-based resin (A) contains a structural unit derived from polycarboxylic acids (a1) and a structural unit derived from polyol (a2). 3. The polyester-based pressure-sensitive adhesive composition according to claim 1, wherein the polyester-based resin (A) has an ester bond concentration of 2 to 11.5 mmol/g. 4. The polyester pressure-sensitive adhesive composition according to any one of claims 1 to 3, wherein the polyoxyalkylene polyol (B) contains structural units derived from ethylene oxide. The polyester pressure-sensitive adhesive composition according to any one of claims 1 to 4, wherein the polyoxyalkylene polyol (B) has a number average molecular weight of 450 to 20,000. The polyester pressure-sensitive adhesive composition according to any one of claims 1 to 5, wherein the hydrolysis inhibitor (C) contains a carbodiimide group-containing compound and/or an oxazoline group-containing compound. 7. The hydrolysis inhibitor (C) according to any one of claims 1 to 6, characterized by containing 0.01 to 10 parts by weight with respect to 100 parts by weight of the polyester resin (A). A polyester pressure-sensitive adhesive composition. The polyester adhesive according to any one of claims 1 to 7, further comprising 0.01 to 15 parts by weight of a crosslinking agent (D) with respect to 100 parts by weight of the polyester resin (A). agent composition. A polyester pressure-sensitive adhesive obtained by cross-linking the polyester pressure-sensitive adhesive composition according to any one of claims 1 to 8. A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer containing the polyester-based pressure-sensitive adhesive according to claim 9. 11. The pressure-sensitive adhesive sheet according to claim 10, which is a substrate-less type having no substrate. 11. The pressure-sensitive adhesive sheet according to claim 10, wherein the pressure-sensitive adhesive layer is formed on at least one side of the substrate. 13. The pressure-sensitive adhesive sheet according to any one of claims 10 to 12, 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 polyester-based pressure-sensitive adhesive according to claim 9 .