Polyester adhesive composition, polyester adhesive, adhesive sheet, and optical component with adhesive layer

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

Technical Field

[0001] The present invention relates to a polyester-based pressure-sensitive adhesive composition, a polyester-based pressure-sensitive adhesive, a pressure-sensitive adhesive sheet, and an optical member with a pressure-sensitive adhesive layer. More specifically, the present invention relates to a polyester-based pressure-sensitive adhesive composition which is excellent in initial adhesive force, is less likely to cause whitening under high temperature and high humidity, and is excellent in optical properties, a pressure-sensitive adhesive obtained by crosslinking 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.

Background Art

[0002] It is known that polyester-based resins, obtained by combining a polycarboxylic acid component and a polyol component, are excellent in chemical resistance, plasticizer resistance, mechanical strength and the like, and their use has also been studied in the field of pressure-sensitive adhesives. As devices using image display devices such as liquid crystal (LC) displays and organic EL (OLED) displays, portable information terminals equipped with touch sensors, represented by smartphones and tablet terminals, are widely known, and each constituent member is bonded via a pressure-sensitive adhesive or a pressure-sensitive adhesive sheet formed from a pressure-sensitive adhesive composition.

[0003] In recent years, with the diversification of consumer preferences, portable information terminals are required to have high designability, and portable information terminals having curved displays and casings are becoming available on the market. Curved glass and curved resin glass are used in such portable information terminals, and pressure-sensitive adhesives used for bonding these optical members are required to be excellent in initial adhesive force that exhibits high adhesive force from the initial stage of bonding, further excellent in optical properties, and prevent the adhesive layer from turning white when used in a high-temperature and high-humidity environment (moisture-heat whitening resistance).

[0004] For example, Patent Document 1 discloses "a polyester-based adhesive composition comprising at least a polyester obtained by polycondensation of a dicarboxylic acid having side chains and a diol, a polyether polyol, and a crosslinking agent, wherein 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 ends and / or at all ends, the number-average molecular weight of the polyether polyol having hydroxyl groups only at some ends is 100 to 1500, and the polyether polyol having hydroxyl groups only at some ends is contained in an amount of 1 to 35 parts by weight per 100 parts by weight of the polyester."

[0005] Furthermore, Patent Document 2 discloses "a polyester adhesive composition containing a polyester resin (A), wherein the polyester resin (A) has structural units derived from polycarboxylic acids (a1) and structural units derived from polyol (a2), and the polycarboxylic acids (a1) contains sulfonic acid base-containing dicarboxylic acids (a1-1), and the content of structural units derived from the sulfonic acid base-containing dicarboxylic acids (a1-1) is 0.0001 to 0.15 mmol / g relative to the polyester resin (A)." [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2013-216875 [Patent Document 2] Japanese Patent Publication No. 2019-85518 [Overview of the project] [Problems that the invention aims to solve]

[0007] In the adhesive composition disclosed in Patent Document 1 mentioned above, a large amount of polyether polyol is contained in a polyester resin with a low ester bond concentration, which leaves unresolved issues in terms of initial adhesive strength and optical properties.

[0008] Furthermore, the adhesive composition disclosed in Patent Document 2 has a problem with its resistance to moist heat because the polyester resin contains a sulfonic acid base, and its resistance to moist heat whitening was also unsatisfactory.

[0009] Therefore, against this background, the present invention aims to provide a polyester-based adhesive composition that exhibits excellent initial adhesive strength, which is higher than the initial adhesive strength after bonding, and also has excellent optical properties and excellent resistance to heat whitening under high temperature and high humidity conditions. Furthermore, the present invention aims to provide an adhesive obtained by crosslinking this adhesive composition, an adhesive sheet having an adhesive layer containing this adhesive, and an optical member with an adhesive layer having the adhesive layer. [Means for solving the problem]

[0010] However, in view of these circumstances, the present inventors conducted extensive research and, as a result, discovered that by including a specific amount of polyoxyalkylene polyol (B) relative to the polyester resin (A) in a polyester adhesive composition containing a polyester resin (A), the present inventors obtained a polyester adhesive composition that exhibits excellent initial adhesive strength, high adhesive strength from the initial stage of bonding, excellent optical properties, and excellent resistance to humid heat whitening under high temperature and high humidity conditions, thereby completing the present invention.

[0011] In other words, the first gist of the present invention is a polyester adhesive composition containing a polyester resin (A), a polyoxyalkylene polyol (B), and a hydrolysis inhibitor (C), characterized in that the content of the polyoxyalkylene polyol (B) is 0.01 to 10 parts by weight per 100 parts by weight of the polyester resin (A).

[0012] Furthermore, the present invention has as a second feature an adhesive obtained by crosslinking the above adhesive composition, as a third feature an adhesive sheet having an adhesive layer containing the above adhesive, and as a fourth feature an optical member with an adhesive layer having the above adhesive layer and an optical member.

[0013] Generally, to improve the moisture-heat resistance of polyester adhesive compositions, one might consider introducing side chain structures into the polyester resin or reducing the ester bond concentration. However, this reduces polarity, decreasing compatibility with various additives and resulting in a deterioration of the transparency of the adhesive sheet. On the other hand, to improve moisture-heat whitening resistance, one might consider introducing polar groups such as sulfonic acid bases or including highly polar additives. However, this increases the hydrophilicity of the resin, accelerating hydrolysis, leading to poor moisture-heat resistance and reduced initial tackiness. Surprisingly, in this invention, by deliberately including a small amount of polyoxyalkylene polyol in the polyester resin, we were able to achieve the objectives of the present invention by obtaining excellent initial tackiness and optical properties, and furthermore, by making it less susceptible to moist heat whitening under high temperature and high humidity conditions. [Effects of the Invention]

[0014] The polyester adhesive composition of the present invention is a polyester adhesive composition containing a polyester resin (A), a polyoxyalkylene polyol (B), and a hydrolysis inhibitor (C), characterized in that the content of the polyoxyalkylene polyol (B) is 0.01 to 10 parts by weight per 100 parts by weight of the polyester resin (A). Therefore, it exhibits excellent initial adhesive strength, which is high from the initial stage of bonding, and also has excellent optical properties and excellent resistance to heat whitening under high temperature and high humidity conditions. It is particularly useful as an adhesive for optical components, and especially as an adhesive for shatterproof films for glass and resin glass. [Modes for carrying out the invention]

[0015] The configuration of the present invention will be described in detail below, but these are merely examples of preferred embodiments. In this specification, each numerical value that defines a numerical range for a given matter can independently define a new numerical range together with other numerical values ​​that define other numerical ranges. For example, if there is a description of "2 to 10% by weight, preferably 4 to 8% by weight" for a given matter, the numerical ranges of "2 to 4% by weight", "2 to 8% by weight", "4 to 10% by weight", and "8 to 10% by weight" may be defined.

[0016] The polyester adhesive composition of the present invention (hereinafter also simply referred to as "adhesive composition") contains a polyester resin (A), a polyoxyalkylene polyol (B), and a hydrolysis inhibitor (C). The following describes in detail each component used in the adhesive composition of the present invention.

[0017] <Polyester resin (A)> Polyester resin (A) is typically obtained by copolymerizing copolymer components containing polycarboxylic acids (a1) and polyols (a2) as constituent raw materials, and the polyester resin (A) contains structural units derived from polycarboxylic acids (a1) and structural units derived from polyols (a2) as part of its resin composition. In this 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.

[0018] [Raw materials for polyester resin (A)] [Polycarboxylic acids (a1)] Examples of polycarboxylic acids (a1) used as constituent raw materials for polyester resin (A) include dicarboxylic acids and polycarboxylic acids with a valency of three or more. Dicarboxylic acids are preferred because they allow for the stable production of polyester resin (A).

[0019] Examples of the above dihydric carboxylic acids include aliphatic dicarboxylic acids such as malonic acids, dimethylmalonic acids, succinic acids, glutaric acids, adipic acids, trimethyladipic acids, pimelic acids, 3-methylglutaric acids, 2,2-dimethylglutaric acids, azelaic acids, sebacic acids, fumaric acids, maleic acids, itaconic acids, thiodipropionic acids, diglycolic acids, and 1,9-nonanedicarboxylic acids; aromatic dicarboxylic acids such as phthalic acids, terephthalic acids, isophthalic acids, benzylmalonic acids, diphenic acids, 4,4'-oxydibenzoic acids, and naphthalenedicarboxylic acids including 1,8-naphthalenedicarboxylic acids, 2,3-naphthalenedicarboxylic acids, and 2,7-naphthalenedicarboxylic acids; alicyclic dicarboxylic acids 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; dimer acids derived from oleic acid, linoleic acid, linolenic acid, erucic acid, and the like; and the like.

[0020] Examples of the above trivalent or higher polycarboxylic acids include trimellitic acids, pyromellitic acids, adamantanetricarboxylic acids, trimesic acids, and the like. One type selected from these polycarboxylic acids (a1) may be used alone, or two or more types may be used in combination.

[0021] Among the above polycarboxylic acids (a1), it is preferable to contain an aromatic polycarboxylic acid (a1-1) from the viewpoint of excellent cohesive strength. In particular, it is more preferable to contain an asymmetric aromatic dicarboxylic acid from the viewpoint of reducing the crystallinity of the polyester resin (A) and providing excellent initial adhesive strength. Asymmetric aromatic dicarboxylic acids refer to aromatic dicarboxylic acids in which the two carboxy groups bonded to the aromatic ring are bonded to the aromatic ring at positions that are not mutually symmetrical. Examples thereof include phthalic acids, isophthalic acids, 1,8-naphthalenedicarboxylic acids, 2,3-naphthalenedicarboxylic acids, 2,7-naphthalenedicarboxylic acids, and the like. Among these, isophthalic acids are particularly preferable in terms of reactivity and optical properties.

[0022] The content of such aromatic polycarboxylic acids (a1-1), particularly asymmetric aromatic dicarboxylic acids, is preferably 1 to 80 mol%, more preferably 3 to 70 mol%, still more preferably 5 to 60 mol%, particularly preferably 10 to 50 mol%, and most preferably 15 to 40 mol%, relative to the total amount (100 mol%) of the polycarboxylic acids (a1) used as constituent raw materials of the polyester resin (A). If the content is too low, cohesive strength tends to decrease, or the resin crystallizes, making it difficult to obtain sufficient adhesive performance. If the content is too high, there is a concern that the glass transition temperature becomes excessively high, the initial adhesive strength decreases, and bonding under pressure of the degree of finger pressing becomes difficult.

[0023] Further, in the present invention, it is preferable that the polycarboxylic acids (a1) contain an aliphatic dicarboxylic acid (a1-2) having a linear structure from the viewpoint of improving initial adhesive strength. Among these, the number of carbon atoms (including the carbon of the carboxy group; the same applies hereinafter) is preferably 4 or more, it is more preferable to contain an aliphatic dicarboxylic acid having 6 to 12 carbon atoms, and it is still more preferable to contain adipic acids, sebacic acids, and azelaic acids.

[0024] The content of such linear aliphatic dicarboxylic acids (a1-2) is preferably 20 to 100 mol%, more preferably 30 to 97 mol%, even more preferably 40 to 95 mol%, particularly preferably 50 to 90 mol%, and especially preferably 60 to 85 mol%, relative to the total polycarboxylic acid (a1) (100 mol%). If the content is too low, the glass transition temperature of the polyester resin (A) tends to become too high, making it difficult to obtain sufficient adhesive strength. If the content is too high, the cohesive strength tends to decrease, or the resin crystallizes, making it difficult to obtain sufficient adhesive performance.

[0025] In the present invention, from the viewpoint of adhesive properties, it is also preferable to use aromatic polycarboxylic acids (a1-1) and linear aliphatic dicarboxylic acids (a1-2) in combination as polycarboxylic acids (a1). In that case, the content ratio (molar ratio) of aromatic polycarboxylic acids (a1-1) to linear aliphatic dicarboxylic acids (a1-2) is preferably (a1-1) / (a1-2) = 1 / 99 to 80 / 20, more preferably 3 / 97 to 70 / 30, even more preferably 5 / 95 to 60 / 40, particularly preferably 10 / 90 to 50 / 50, and especially preferably 15 / 85 to 40 / 60.

[0026] Furthermore, in the present invention, polycarboxylic acids (a1-3) having hydrocarbon groups in their side chains can also be used, as this can disrupt the crystallinity of the polyester resin (A). Examples of hydrocarbon groups in the side chains include alkyl groups and alkylene groups, and two or more hydrocarbon groups may be bonded to form a cyclic structure. The number of carbon atoms in the hydrocarbon groups of the side chains is preferably 1 to 20, more preferably 1 to 10, even more preferably 1 to 5, and particularly preferably 1 to 3. If the number of carbon atoms in the hydrocarbon groups of the side chains is too high, the compatibility with polyoxyalkylene polyols (B) and hydrolysis agents (C) tends to decrease. Examples of polycarboxylic acids (a1-3) having hydrocarbon groups in their side chains include: Examples include dimethylmalonic acids; trimethyladipic acids; 3-methylglutaric acids; and dimer acids derived from oleic acid, linoleic acid, linolenic acid, erucic acid, etc.

[0027] The content of dicarboxylic acids (a1-3) having hydrocarbon groups in their side chains is preferably 80 mol% or less, more preferably 60 mol% or less, even more preferably 40 mol% or less, particularly preferably 20 mol% or less, and especially preferably 10 mol% or less, relative to the total polycarboxylic acids (a1) (100 mol%). If the content is too high, the cohesive force tends to decrease, and the compatibility with polyoxyalkylene polyol (B) and hydrolysis agent (C) deteriorates, leading to a decrease in optical properties. The content of dicarboxylic acids (a1-3) having hydrocarbon groups in their side chains may be 0 mol%.

[0028] Furthermore, in the present invention, polycarboxylic acids (a1-4) with a valency of trivalent or higher can be used in the polyester resin (A) for the purpose of increasing the number of branching points. In particular, it is preferable to use polycarboxylic acids that contain aromatic structures and have a valency of trivalent or higher, as they are less likely to gel during manufacturing. For example, trimellitic acids are preferred.

[0029] The content of the trivalent or higher polycarboxylic acids (a1-4) is preferably 10 mol% or less, and more preferably 0.1 to 5 mol%, relative to the total polycarboxylic acid (a1) (100 mol%), in order to enhance the cohesive force when preparing the adhesive. If the content is too high, gelation tends to occur during the production of the polyester resin (A). The content of trivalent or higher polycarboxylic acids (a1-4) may be 0 mol%.

[0030] [Polyol (a2)] Examples of polyols (a2) used as constituent raw materials for polyester resin (A) include dihydric alcohols and trihydric or higher polyols.

[0031] Examples of the above-mentioned dihydric alcohols include aliphatic diols such as 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, and 2,2,4-trimethyl-1,6-hexanediol; Alicyclic diols such as 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, spiroglycol, tricyclodecanedimethanol, adamantanediol, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol; Examples include paraxylene glycol, metaxylene glycol, orthoxylene 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 their hydrogenated products, and aromatic diols such as ethylene oxide adducts and propylene oxide adducts obtained by adding 1 to several moles of ethylene oxide or propylene oxide to the hydroxyl group of bisphenols. Furthermore, examples include fatty acid esters derived from castor oil; dimer ols derived from oleic acid, linoleic acid, linolenic acid, erucic acid, etc.; glycerol monostearate; and the like. Furthermore, examples include polyoxyalkylenediols such as polyethylene glycol, polypropylene glycol, polybutylene glycol, and polytetramethylene glycol; copolymerized polyoxyalkylenediols of 3-methyltetrahydrofuran and tetrahydrofuran, copolymerized polyoxyalkylenediols of neopentyl glycol and tetrahydrofuran, copolymerized polyoxyalkylenediols of polyethylene glycol and polypropylene glycol, copolymerized polyoxyalkylenediols of polyethylene glycol and polypropylene glycol, copolymerized polyoxyalkylenediols of polyethylene glycol and polybutylene glycol, and copolymerized polyoxyalkylenediols of polyethylene glycol and polytetramethylene glycol.

[0032] Examples of the above-mentioned polyols with a valent or higher valentity include pentaerythritol, dipentaerythritol, tripentaerythritol, glycerin, trimethylolpropane, trimethylolethane, 1,2,4-butanetriol, 1,2,5-pentanetriol, 1,2,6-hexanetriol, 1,3,6-hexanetriol, and adamantanetriol. One of these polyols (a2) can be used alone or in combination of two or more.

[0033] In the present invention, among polyols (a2), aromatic polyols (a2-1) that can form structural units derived from aromatic structure-containing compounds can also be included due to their excellent cohesive strength. Examples of such polyols include paraxylene glycol, metaxylene glycol, orthoxylene 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 their hydrogenated products, and ethylene oxide adducts and propylene oxide adducts obtained by adding 1 to several moles of ethylene oxide or propylene oxide to the hydroxyl group of bisphenols. Among these, ethylene oxide adducts of bisphenols are preferred due to their excellent reactivity.

[0034] The content of such aromatic polyol (a2-1) is preferably 1 to 80 mol%, more preferably 3 to 70 mol%, even more preferably 5 to 60 mol%, particularly preferably 10 to 50 mol%, and especially preferably 15 to 40 mol%, relative to the total polyol (a2) (100 mol%). If the content is too low, the cohesive force tends to decrease. If the content is too high, there is a concern that the initial tackiness will decrease, or that the reaction time during the production of the polyester resin (A) will be prolonged, reducing the production efficiency.

[0035] Furthermore, it is preferable to include a linear aliphatic diol (a2-2) in the polyol (a2) in order to lower the glass transition temperature (Tg) of the polyester resin (A) and improve the initial tackiness. More preferably, it is a linear aliphatic diol having 2 to 18 carbon atoms, and particularly preferably ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, or 1,6-hexanediol.

[0036] The content of the linear aliphatic diol (a2-2) is preferably 5 to 100 mol%, more preferably 10 to 95 mol%, even more preferably 15 to 90 mol%, particularly preferably 20 to 80 mol%, and especially preferably 30 to 70 mol%, relative to the total polyol (a2) (100 mol%). If the content is too low, the glass transition temperature tends to become too high, reducing the initial tackiness and making bonding with pressure equivalent to finger pressure difficult, and making it difficult to obtain a stable resin formation. If the content is too high, the resin tends to crystallize, reducing the initial tackiness.

[0037] Furthermore, among the polyols (a2) mentioned above, it is preferable to include a diol (a2-3) having a hydrocarbon group in the side chain, as this can disrupt the crystallinity. Examples of hydrocarbon groups in the side chain include alkyl groups and alkylene groups, and two or more hydrocarbon groups may be bonded to form a cyclic structure. The number of carbon atoms in the hydrocarbon group in the side chain is preferably 1 to 20, more preferably 1 to 10, even more preferably 1 to 5, and particularly preferably 1 to 3. If the number of carbon atoms in the hydrocarbon group in the side chain is too high, the compatibility with polyoxyalkylene polyol (B) and hydrolysis agent (C) tends to decrease. Examples of diols (a2-3) having hydrocarbon groups in their side chains 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, and 3-methyl-1,5-pentanediol. Examples include branched aliphatic diols such as tandiols and 2,2,4-trimethyl-1,6-hexanediol; branched alicyclic diols such as 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, spiroglycol, tricyclodecanedimethanol, adamantanediol, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol; and dimerols derived from oleic acid, linoleic acid, linolenic acid, erucic acid, etc. Among these, branched aliphatic diols are preferred, with 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), and 3-methyl-1,5-pentanediol being particularly preferred.

[0038] The content of the diol (a2-3) having hydrocarbon groups in its side chain is preferably 5 to 95 mol%, more preferably 10 to 90 mol%, even more preferably 15 to 80 mol%, particularly preferably 20 to 70 mol%, and especially preferably 30 to 60 mol%, relative to the total polyol (a2) (100 mol%). If the content is too low, the resin tends to crystallize and the initial tackiness decreases, and if it is too high, the reaction time during the production of the polyester resin (A) tends to be longer and the production efficiency tends to decrease.

[0039] Furthermore, in the present invention, it is also preferable to use a polyol (a2-4) with a trivalent or higher valent

[0040] The content of such trivalent or higher polyols (a2-4) is preferably 10 mol% or less, and more preferably 0.1 to 5 mol%, relative to the total polyol (a2) (100 mol%). If the content of such trivalent or higher polyols is too high, it tends to become difficult to manufacture the polyester resin (A).

[0041] Furthermore, among the polyols (a2) mentioned above, polyoxyalkylenediols (a2-5) can also be included due to their excellent resistance to moisture and heat whitening. Examples of polyoxyalkylenediols (a2-5) include bifunctional polyoxyalkylene polyols such as polyethylene glycol, polypropylene glycol, polybutylene glycol, and polytetramethylene glycol; copolymerized polyoxyalkylenediols such as 3-methyltetrahydrofuran and tetrahydrofuran copolymerized polyoxyalkylenediol, neopentyl glycol and tetrahydrofuran copolymerized polyoxyalkylenediol, polyethylene glycol and polypropylene glycol copolymerized polyoxyalkylenediol, polyethylene glycol and polybutylene glycol copolymerized polyoxyalkylenediol, and polyethylene glycol and polytetramethylene glycol copolymerized polyoxyalkylenediol; and the like. In particular, polyoxyalkylenediols having a linear structure without side chains are preferred because they have excellent resistance to moisture and heat whitening, are less prone to a decrease in adhesive strength, and have excellent reworkability and adhesive reliability. They are more preferably having structural units derived from ethylene oxide, and polyethylene glycol is especially preferred.

[0042] The content of polyoxyalkylenediol (a2-5) is preferably 30 mol% or less, more preferably 0.01 to 20 mol%, even more preferably 0.1 to 10 mol%, particularly preferably 0.2 to 5 mol%, especially preferably 0.3 to 3 mol%, and most preferably 0.5 to 1.5, relative to the total polyol (a2) (100 mol%). If the content of such polyoxyalkylenediol (a2-5) is too high, the initial tackiness and optical properties of the polyester resin (A) tend to decrease.

[0043] [Method for manufacturing polyester resin (A)] The polyester resin used in the present invention is produced by appropriately selecting the above polycarboxylic acids (a1) and the above polyol (a2), and carrying out a polycondensation reaction of them in the presence of a catalyst using a known method.

[0044] The preferred blending ratio of the polycarboxylic acid (a1) to the polyol (a2) is 1 to 2 equivalents of polyol (a2) per equivalent of polycarboxylic acid (a1), and more preferably 1.1 to 1.7 equivalents. If the blending ratio of polyol (a2) is too low, the acid value tends to increase, making it difficult to increase the molecular weight, and if it is too high, the yield tends to decrease.

[0045] In a polycondensation reaction, an esterification reaction takes place first, followed by the polycondensation reaction.

[0046] In such esterification reactions, catalysts are usually used. Specifically, examples include 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, and dibutyltin oxide. One of 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 due to their high catalytic activity and balance of color, with tetrabutyl titanate and zinc acetate being more preferred.

[0047] The amount of catalyst added is preferably 1 to 10,000 ppm by weight relative to the total copolymer components, more preferably 10 to 5,000 ppm, and even more preferably 20 to 3,000 ppm. If the amount is too low, the polymerization reaction tends not to proceed sufficiently, and if it is too high, there is no advantage such as shortening the reaction time, and side reactions tend to occur easily.

[0048] The reaction temperature during the esterification reaction is preferably 200 to 300°C, more preferably 210 to 280°C, and even more preferably 220 to 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. The reaction pressure is usually atmospheric pressure.

[0049] After the esterification reaction described above takes place, a polycondensation reaction is carried out. For the polycondensation reaction, it is preferable to use the same catalyst as that used in the esterification reaction described above, in an equal amount, and to set the reaction temperature to preferably 220-280°C, more preferably 230-270°C, gradually reducing the pressure of the reaction system until the final reaction is carried out 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 easily.

[0050] Thus, a polyester resin (A) is obtained.

[0051] [Structure of polyester resin (A)] The above polyester resin (A) typically contains structural units derived from polycarboxylic acids (a1) and structural units derived from polyols (a2). When structural units derived from aromatic polycarboxylic acids (a1-1), which can form structural units derived from the above aromatic structure-containing compound, are included as structural units derived from polycarboxylic acids (a1), it is preferable that the amount of structural units derived from aromatic polycarboxylic acids (a1-1) is 1 to 80 mol%, more preferably 3 to 70 mol%, even more preferably 5 to 60 mol%, particularly preferably 10 to 50 mol%, and especially preferably 15 to 40 mol% of the amount of structural units derived from polycarboxylic acids (a1). If the content is too low, the cohesive force tends to decrease. If the content is too high, there is a concern that the initial tackiness will decrease.

[0052] When the linear aliphatic dicarboxylic acid (a1-2) structural units are included as structural units derived from polycarboxylic acid (a1), it is preferable that the linear aliphatic dicarboxylic acid (a1-2) structural units constitute 20 to 100 mol%, more preferably 30 to 97 mol%, even more preferably 40 to 95 mol%, particularly preferably 50 to 90 mol%, and especially preferably 60 to 85 mol% of the structural units derived from polycarboxylic acid (a1). If the content is too low, the glass transition temperature of the polyester resin (A) tends to become too high, making it difficult to obtain sufficient adhesive strength. If the content is too high, the cohesive strength tends to decrease, or the resin crystallizes, making it difficult to obtain sufficient adhesive performance.

[0053] When the structural units derived from polycarboxylic acids (a1-3) having hydrocarbon groups in their side chains are included as structural units derived from polycarboxylic acid (a1), it is preferable that the structural units derived from polycarboxylic acids (a1-3) having hydrocarbon groups in their side chains constitute 80 mol% or less of the structural units derived from polycarboxylic acid (a1), more preferably 60 mol% or less, even more preferably 60 mol% or less, particularly preferably 40 mol% or less, especially preferably 20 mol% or less, and even more preferably 10 mol% or less. If the content is too high, the cohesive force tends to decrease, and the compatibility with polyoxyalkylene polyol (B) and hydrolysis inhibitor (C) tends to decrease.

[0054] When structural units derived from the above-mentioned trivalent or higher polycarboxylic acids (a1-4) are included as structural units derived from polycarboxylic acid (a1), it is preferable that the amount of structural units derived from trivalent or higher polycarboxylic acids (a1-4) is 10 mol% or less of the amount of structural units derived from polycarboxylic acid (a1), and more preferably 0.1 to 5 mol%. If the content is too high, gelation tends to occur easily during the production of the polyester resin (A).

[0055] Furthermore, when structural units derived from aromatic polyol (a2-1), which can form structural units derived from the above-mentioned aromatic structure-containing compound, are included as structural units derived from polyol (a2), it is preferable that the amount of structural units derived from aromatic polyol (a2-1) is 1 to 80 mol%, more preferably 3 to 70 mol%, even more preferably 5 to 60 mol%, particularly preferably 10 to 50 mol%, and especially preferably 15 to 40 mol% of the amount of structural units derived from polyol (a2). If the content is too low, the cohesive force tends to decrease. If the content is too high, there is a concern that the initial tackiness will decrease, or that the reaction time will be longer during the production of the polyester resin (A), leading to a decrease in production efficiency.

[0056] When the linear aliphatic diol (a2-2) derived structural units are included as polyol (a2) derived structural units, it is preferable that the linear aliphatic diol (a2-2) derived structural units constitute 5 to 100 mol%, more preferably 10 to 95 mol%, even more preferably 15 to 90 mol%, particularly preferably 20 to 80 mol%, and especially preferably 30 to 70 mol% of the polyol (a2) derived structural units. If the content is too low, the reaction time during the production of the polyester resin (A) tends to be longer, and the production efficiency tends to decrease. If the content is too high, there is a concern that the polyester resin (A) will crystallize, and the initial adhesive strength of the adhesive will decrease.

[0057] When structural units derived from diols (a2-3) having hydrocarbon groups in their side chains are included as structural units derived from polyol (a2), it is preferable that the amount of structural units derived from diols (a2-3) having hydrocarbon groups in their side chains is 5 to 95 mol%, more preferably 10 to 90 mol%, even more preferably 15 to 80 mol%, particularly preferably 20 to 70 mol%, and especially preferably 30 to 60 mol% of the amount of structural units derived from polyol (a2). If the content is too low, the polyester resin (A) tends to crystallize, and the initial adhesive strength of the adhesive tends to decrease. If the content is too high, the reaction time during the production of the polyester resin (A) tends to increase, and the production efficiency tends to decrease.

[0058] Furthermore, when structural units derived from the trivalent or higher polyol (a2-4) are included as structural units derived from polyol (a2), it is preferable that the amount of structural units derived from the trivalent or higher polyol (a2-4) is 10 mol% or less of the amount of structural units derived from polyol (a2), and more preferably 0.1 to 5 mol%. If the content is too high, the polyester resin (A) tends to gel during manufacturing, making manufacturing difficult.

[0059] Here, the proportion of structural units (composition ratio) derived from each component of the polyester resin (A) can be determined, for example, by NMR.

[0060] [Physical properties of polyester resin (A)] The polyester resin (A) described above preferably has the following physical properties.

[0061] The glass transition temperature (Tg) of the above polyester resin (A) is preferably -80 to 10°C, more preferably -70 to 0°C, even more preferably -65 to -10°C, particularly preferably -60 to -15°C, especially preferably -55 to -20°C, and even more preferably -50 to -30°C, from the viewpoint of adhesive properties. If the glass transition temperature (Tg) is too high, flexibility is lost, the initial adhesive strength decreases, and it tends to become difficult to exert adhesive strength even when pressure such as finger pressure is applied. If it is too low, the cohesive strength tends to decrease.

[0062] 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 Corporation. The measurement temperature range is -90 to 100°C, and the temperature rise rate is 10°C / minute.

[0063] The number-average molecular weight (Mn) of the above polyester resin (A) is usually 1,000 to 100,000, from the viewpoint of the cohesive force of the adhesive. Preferably it is 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 force as an adhesive cannot be obtained, and heat resistance and mechanical strength tend to decrease. Also, if the number-average molecular weight is too large, adhesion to the substrate tends to decrease.

[0064] The weight-average molecular weight (Mw) of the above polyester resin (A) is typically 5,000 to 300,000, from the viewpoint of the cohesive force of the adhesive. Preferably it is 8,000 to 200,000, more preferably 10,000 to 180,000, even 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 force as an adhesive cannot be obtained, and heat resistance and mechanical strength tend to decrease. Conversely, if the weight-average molecular weight is too large, adhesion to the substrate tends to decrease.

[0065] The number-average amount (Mn) and weight-average molecular weight (Mw) of polyester resin (A) are average molecular weights calculated on a standard polystyrene molecular weight scale, and are measured using a high-performance liquid chromatograph (Waters, "ACQUITY APC system") with a total of four columns in series: one ACQUITY APC XT 450, one ACQUITY APC XT 200, and two ACQUITY APC XT 45.

[0066] The hydroxyl value of the above polyester resin (A) is preferably 1 to 50 mg KOH / g, more preferably 2 to 30 mg KOH / g, even more preferably 3 to 20 mg KOH / g, and particularly preferably 4 to 15 mg KOH / g. If the hydroxyl value is too high, the crosslinking efficiency with the crosslinking agent (D) described later tends to decrease, and if it is too low, the cohesive force tends to decrease.

[0067] The acid value of the above polyester resin (A) is preferably 10 mg KOH / g or less, more preferably 5 mg KOH / g or less, even more preferably 3 mg KOH / g or less, particularly preferably 1 mg KOH / g or less, and especially preferably 0.5 mg KOH / g or less. If the acid value is too high, hydrolysis tends to proceed easily, which tends to reduce the moisture heat durability, adhesive strength, and moisture heat whitening resistance, and also tends to corrode the metal when a layer such as metal is bonded to one side of the adhesive layer.

[0068] Here, the hydroxyl value and acid value mentioned above are determined by neutralization titration in accordance with JIS K 0070.

[0069] The ester bond concentration of the polyester resin (A) is typically 1 to 15 mmol / g, preferably 1.5 to 14 mmol / g, more preferably 2 to 13 mmol / g, even more preferably 3 to 12 mmol / g, particularly preferably 3.5 to 11 mmol / g, especially preferably 4 to 10.5 mmol / g, even more preferably 5 to 10 mmol / g, even more preferably 6 to 9.5 mmol / g, and most preferably 7 to 9 mmol / g. If the ester bond concentration is too low, the compatibility with polyoxyalkylene polyol (B) and hydrolysis inhibitor (C) tends to be poor, resulting in a decrease in optical properties. If the ester bond concentration is too high, the resistance to moist heat tends to decrease. The definition and measurement method for the ester bond concentration of the above-mentioned polyester resin (A) are as follows. Ester bond concentration (mmol / g) refers to the number of moles of ester bonds in 1g of polyester resin (A), and can be calculated, for example, from the amount used. This calculation method involves dividing the smaller number of moles of polycarboxylic acids and polyhydric alcohols by the total weight of the resin. An example of the calculation formula is shown below. Furthermore, if the amounts of polycarboxylic acids and polyhydric alcohols used are the same in molar quantities, either of the following calculation formulas may be used. Furthermore, when using monomers that possess both carboxyl and hydroxyl groups, or when producing polyesters from caprolactone, etc., the calculation method will need to be adjusted accordingly.

[0070] (When polycarboxylic acids are present in smaller quantities than polyalcohols) Ester group concentration (mmol / g) = [(A1 / a1×m1 + A2 / a2×m2 + A3 / a3×m3···) / Z] × 1000 A: Amount of polycarboxylic acids added (g) a: Molecular weight of polycarboxylic acids m: Number of carboxylic acid groups per molecule of polycarboxylic acid Z: Finished weight (g)

[0071] (When polyhydric alcohols are less abundant than polyhydric carboxylic acids) Ester group concentration (mmol / g) = [(B1 / b1×n1 + B2 / b2×n2 + B3 / b3×n3···) / Z] × 1000 B: Amount of polyhydric alcohols added (g) b: Molecular weight of polyhydric alcohols n: Number of hydroxyl groups per molecule of polyhydric alcohol Z: Finished weight (g)

[0072] The ester bond concentration mentioned above can also be measured using known methods such as NMR.

[0073] <Polyoxyalkylene polyol (B)> Polyoxyalkylene polyol (B) imparts moisture- and heat-induced whitening resistance to polyester adhesive compositions. By adding a small amount, it is possible to achieve excellent moisture- and heat-induced whitening resistance without impairing initial tackiness or optical properties. Furthermore, the above polyoxyalkylene polyol (B) is not included as polyoxyalkylenediol (a2-5), which is a constituent raw material of polyester resin (A), but rather as a different component from polyester resin (A). This allows for excellent moisture- and heat-induced whitening resistance without impairing initial tackiness, and also results in excellent optical properties without being affected by the thermal history during the manufacturing of the polyester resin.

[0074] [Types of polyoxyalkylene polyols (B)] The polyoxyalkylene polyol (B) mentioned above is not particularly limited, and conventionally known polyols can be used. Examples include bifunctional polyoxyalkylene polyols such as polyethylene glycol, polypropylene glycol, polybutylene glycol, and polytetramethylene glycol; trifunctional polyoxyalkylene polyols such as trimethylolpropane tripolyoxyethylene ether; tetrafunctional polyoxyalkylene polyols such as pentaerythritol polyoxyethylene ether; copolymerized polyoxyalkylene polyols of 3-methyltetrahydrofuran and tetrahydrofuran, copolymerized polyoxyalkylene polyols of neopentyl glycol and tetrahydrofuran, copolymerized polyoxyalkylene polyols of polyethylene glycol and polypropylene glycol, copolymerized polyoxyalkylene polyols of polyethylene glycol and polybutylene glycol, copolymerized polyoxyalkylene polyols of polyethylene glycol and polytetramethylene glycol, and copolymerized polyoxyalkylene polyols of polyethylene glycol and polytetramethylene glycol. Among these, polyoxyalkylene polyols having a linear structure without side chains are preferred because they have excellent resistance to moisture and heat whitening and are less prone to a decrease in adhesive strength, and it is more preferable that they have structural units derived from ethylene oxide, and polyethylene glycol is particularly preferred. One of these can be used alone or in combination of two or more.

[0075] Furthermore, as the polyoxyalkylene polyol (B), a polyoxyalkylene polyol (B) in which some of the terminal hydroxyl groups have been modified may be used. For example, some of the terminal hydroxyl groups of the polyoxyalkylene polyol (B) may be modified with aliphatic hydrocarbon groups such as methyl, ethyl, allyl, propyl, butyl, and 2-ethylhexyl groups; or aromatic hydrocarbon groups such as phenyl, methylphenyl, nonylphenyl, and benzyl groups, thereby eliminating reactivity. However, if all terminal hydroxyl groups are modified, reactivity will be completely eliminated, making it impossible to crosslink with the polyester resin (A), and the polyoxyalkylene polyol (B) will be more likely to bleed out to the adhesive surface, resulting in a tendency for the initial tackiness to decrease.

[0076] [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 4,000, especially preferably 1,000 to 3,000, and most preferably 1,500 to 2,500. If the number-average molecular weight of the polyoxyalkylene polyol (B) is too small, the resistance to humid heat whitening tends to decrease, and if the number-average molecular weight is too large, the initial tackiness tends to decrease, and the compatibility with polyester resin (A) tends to be poor, resulting in reduced optical properties.

[0077] 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, even more preferably 0.2 to 6 parts by weight, particularly preferably 0.3 to 5 parts by weight, especially preferably 0.4 to 4 parts by weight, and most preferably 0.5 to 3 parts by weight, per 100 parts by weight of polyester resin (A). If the content of polyoxyalkylene polyol (B) is too low, the resistance to humid heat whitening tends to decrease, and if the content is too high, the initial tackiness and optical properties tend to decrease.

[0078] <Hydrolysis inhibitor (C)> The adhesive composition of the present invention preferably further contains a hydrolysis inhibitor (C). By including such a hydrolysis inhibitor (C), long-term durability of the polyester-based adhesive composition can be further ensured.

[0079] Conventionally known compounds can be used as the hydrolysis inhibitor (C) described above. For example, compounds that react and bond with the carboxyl group terminals of the polyester resin (A) can be used. Specifically, examples include compounds containing functional groups such as carbodiimide groups, epoxy groups, and oxazoline groups. One of these can be used alone or in combination of two or more as the hydrolysis inhibitor (C). Among these, carbodiimide group-containing compounds and oxazoline group-containing compounds are preferred because they have a high effect 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 compounds and oxazoline group-containing compounds.

[0080] Examples of the above-mentioned carbodiimide group-containing compounds include known carbodiimide compounds that typically have one or more carbodiimide groups (-N=C=N-) in their molecule. Among these, compounds containing two or more carbodiimide groups in their molecule, i.e., polyvalent carbodiimide compounds, are preferred, and compounds containing three or more, more preferably five or more, and especially seven or more, carbodiimide groups in their molecule are preferred. The number of carbodiimide groups in the above-mentioned polyvalent carbodiimide compounds is 50 or less. If the number of carbodiimide groups is too large, there is a concern that the compatibility with polyester resin (A) will decrease.

[0081] Furthermore, as the carbodiimide group-containing compound, it is also preferable to use a high molecular weight polycarbodiimide produced by decarboxylating and condensing a diisocyanate in the presence of a carbodiimide catalyst.

[0082] Such high molecular weight polycarbodiimides may be synthesized or commercially available. When synthesizing high molecular weight polycarbodiimides, examples include those obtained by decarboxylation condensation of the following diisocyanates.

[0083] Examples of such diisocyanates include 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 others. One of these can be used alone or in combination of two or more.

[0084] Furthermore, in terms of storage stability, the above-mentioned high molecular weight polycarbodiimides are preferable if their terminal isocyanate groups are sealed with a sealing agent. Examples of sealing agents include compounds having active hydrogen that reacts with isocyanate groups, or compounds having isocyanate groups. For example, examples include compounds having one substituent selected from carboxyl groups, amino groups, and isocyanate groups (e.g., monoalcohols, monocarboxylic acids, monoamines, and monoisocyanates).

[0085] The carbodiimide equivalent of the above carbodiimide group-containing compound is preferably 50 to 10000, more preferably 100 to 1000, and even more preferably 150 to 500. Note that carbodiimide equivalent refers to the chemical formula weight per carbodiimide group.

[0086] Furthermore, commercially available carbodiimide group-containing compounds may also be used. Examples of commercially available carbodiimide group-containing compounds include the Carbodilite® series manufactured by Nisshinbo Chemical Co., Ltd., and among these, Carbodilite® "V-01", "V-02B", "V-03", "V-04K", "V-04PF", "V-05", "V-07", "V-09", "V-09GB", and "H-01" are preferred due to their excellent compatibility with polyester resin (A).

[0087] Examples of the epoxy group-containing compounds mentioned above include glycidyl ester compounds and glycidyl ether compounds. One of these can be used alone or in combination of two or more. Examples of glycidyl ester compounds include glycidyl benzoate, t-up-glycidyl benzoate, p-glycidyl toluate, glycidyl cyclohexanecarboxylic acid, glycidyl pelargonic acid, glycyl stearate, glycidyl laurate, glycidyl palmitate, glycidyl behenate, glycidyl versatate, glycidyl oleate, glycidyl linoleate, glycidyl linolenic acid, glycidyl behenolate, glycidyl stearolate, diglycidyl terephthalate, and diglycidyl isophthalate. Examples include diglycidyl phthalate, diglycidyl naphthalenedicarboxylate, diglycidyl methylterephthalate, diglycidyl hexahydrophthalate, diglycidyl tetrahydrophthalate, diglycidyl cyclohexanedicarboxylate, diglycidyl adipicate, diglycidyl succinate, diglycidyl sebacate, diglycidyl dodecandionate, diglycidyl octadecanedicarboxylate, triglycidyl trimelliticate, tetraglycidyl pyromelliticate, and others. One of these can be used alone or in combination of two or more.

[0088] 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-[r-(β,γ-epoxypropoxy)phenyl]propane, and bisglycidyl polyethers obtained by the reaction of bisphenols such as 2,2-bis-(4-hydroxyphenyl)propane and 2,2-bis-(4-hydroxyphenyl)methane with epichlorohydrin. One of these can be used alone or in combination of two or more.

[0089] As the oxazoline group-containing compound mentioned above, bisoxazoline compounds and the like are preferred. 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' Examples include -tetramethylenebis(4,4-dimethyl-2-oxazoline), 2,2'-9,9'-diphenoxyethanebis(2-oxazoline), 2,2'-cyclohexylenebis(2-oxazoline), and 2,2'-diphenylenebis(2-oxazoline). One of these can be used alone or in combination of two or more.

[0090] These hydrolysis inhibitors (C) are preferably those with low volatility. For this reason, it is preferable to use those with a high number-average molecular weight, usually 300 to 10,000, preferably 1,000 to 5,000. Furthermore, from the viewpoint of hydrolysis resistance, it is preferable to use a hydrolysis inhibitor (C) with a high weight-average molecular weight. The weight-average molecular weight of the hydrolysis inhibitor (C) is preferably 500 or more, more preferably 2000 or more, and even more preferably 3000 or more. The upper limit of the weight-average molecular weight is usually 50000. If the molecular weight of the hydrolysis inhibitor (C) is too small, hydrolysis resistance tends to decrease. Furthermore, if the molecular weight is too large, there is a concern that compatibility with the polyester resin (A) will be poor, leading to a decrease in optical properties.

[0091] 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, even more preferably 0.3 to 3 parts by weight, and particularly preferably 0.5 to 2 parts by weight, per 100 parts by weight of the polyester resin (A). If the content is too high, poor compatibility with the polyester resin (A) tends to reduce optical properties and initial tackiness, while if it is too low, it tends to be difficult to obtain sufficient durability.

[0092] Furthermore, 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 molar ratio [(Y) / (X)] of the total number of moles of functional groups (Y) of the hydrolysis inhibitor (C) in the adhesive composition to the total number of moles (X) of acidic functional groups (A) in the adhesive composition is preferably 0.5 ≤ (Y) / (X), more preferably 1 ≤ (Y) / (X) ≤ 1000, even more preferably 1.5 ≤ (Y) / (X) ≤ 100, particularly preferably 2 ≤ (Y) / (X) ≤ 50, especially preferably 2.5 ≤ (Y) / (X) ≤ 30, and most preferably 3 ≤ (Y) / (X) ≤ 15. If the molar ratio of (Y) to (X) is too low, the moisture and heat resistance tends to decrease. Conversely, if the molar ratio of (Y) to (X) is too high, there is a concern that the compatibility with the polyester resin (A) will decrease, resulting in inferior optical properties or reduced initial tackiness.

[0093] <Crosslinking agent (D)> The adhesive composition of the present invention preferably further contains a crosslinking agent (D). Examples of the crosslinking agent (D) include compounds having a functional group that reacts with at least one of the hydroxyl group and carboxyl group contained in the polyester resin (A), such as polyisocyanate compounds and polyepoxy compounds. Among these, polyisocyanate compounds are particularly preferred because they can achieve a good balance between initial tackiness, mechanical strength, and heat resistance.

[0094] 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, and triphenylmethane triisocyanate. Furthermore, adducts of these polyisocyanates with polyol compounds such as trimethylolpropane, as well as bilets and isocyanurates of these polyisocyanate compounds, can also be used. Note that the above polyisocyanate compounds can also be used in which the isocyanate portion is blocked by phenol, lactam, etc. One of these crosslinking agents (D) can be used alone or in combination of two or more.

[0095] The content of the crosslinking agent (D) is preferably 0.01 to 15 parts by weight, more preferably 0.1 to 10 parts by weight, even more preferably 0.3 to 8 parts by weight, particularly preferably 0.5 to 5 parts by weight, and especially preferably 1.0 to 3.0 parts by weight, per 100 parts by weight of the polyester resin (A). If the content is too high, the adhesive strength of the polyester resin (A) tends to decrease, and the resistance to humid heat whitening tends to decrease, while if it is too low, it tends to be difficult to obtain sufficient durability.

[0096] The content of the crosslinking agent (D) can be appropriately set according to the amount of hydroxyl groups and carboxyl groups contained in the polyester resin (A). For example, it is preferable that the crosslinking agent (D) is contained in a ratio of 0.2 to 10 equivalents of reactive groups contained in the crosslinking agent (D) to 1 equivalent of at least one of the hydroxyl groups and carboxyl groups contained in the polyester resin (A), more preferably 0.5 to 5 equivalents, and even more preferably 0.5 to 3 equivalents. If the equivalent number of reactive groups in the crosslinking agent (D) is too small, the cohesive force tends to decrease, and if it is too large, the flexibility tends to decrease.

[0097] Furthermore, in the reaction between the polyester resin (A) and the polyoxyalkylene polyol (B) and the crosslinking agent (D), organic solvents that do not have functional groups that react with components (A), (B), and (D) can be used. For example, esters such as ethyl acetate and butyl acetate; ketones such as methyl ethyl ketone and methyl isobutyl ketone; aromatics such as toluene and xylene; and other organic solvents can be used. One of these organic solvents can be used alone or in combination of two or more.

[0098] <Urethane catalyst (E)> The adhesive composition of the present invention preferably further contains a urethane catalyst (E). As the urethane catalyst (E) mentioned above, for example, organometallic compounds, tertiary amine compounds, etc., can be used. One of these can be used alone, or two or more can be used in combination.

[0099] Examples of the above-mentioned organometallic compounds include zirconium compounds, iron compounds, tin compounds, titanium compounds, lead compounds, cobalt compounds, and zinc 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-based compounds include dibutyltitanium dichloride, tetrabutyltitanate, and butoxytitanium trichloride. Examples of lead-based 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.

[0100] Examples of the above-mentioned tertiary amine compounds include triethylamine, triethylenediamine, and 1,8-diazabicyclo-(5,4,0)-undecene-7.

[0101] Among these urethane catalysts (E), organometallic compounds are preferred in terms of reaction rate and pot life of the adhesive layer, zirconium compounds are more preferred, and zirconium acetylacetonate is even more preferred.

[0102] The content of the urethane catalyst (E) is preferably 0.001 to 1 part by weight, more preferably 0.005 to 0.5 parts by weight, even more preferably 0.01 to 0.1 parts by weight, and particularly preferably 0.02 to 0.05 parts by weight, per 100 parts by weight of the polyester resin (A). If the content is too high, the moisture and heat resistance tends to decrease.

[0103] [Catalyst inhibitor] In the adhesive composition of the present invention, it is preferable to include a catalytic inhibitor in the urethane catalyst (E) in order to extend the pot life and improve coating properties. Examples of catalyst inhibitors include β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, octyl acetoacetate, oleyl acetoacetate, lauryl acetoacetate, and stearyl acetoacetate; and β-diketones such as acetylacetone, 2,4-hexanedione, and benzoylacetone. These are ketoenol tautomer compounds, and by protecting the urethane catalyst (E), they reduce the catalytic activity of the urethane catalyst (E) in solution, suppressing excessive viscosity increase and gelation of the adhesive composition after compounding, and extending the pot life of the adhesive composition. Among these, acetylacetone is preferred as a catalyst inhibitor due to the balance between pot life and curing speed. One of these catalyst inhibitors can be used alone or in combination of two or more.

[0104] The mixing ratio (by weight) of the catalyst inhibitor and the urethane catalyst (E) is preferably in the range of catalyst inhibitor:urethane catalyst (E) = 0.001:1 to 15:1, more preferably 0.005:1 to 13:1, and even more preferably 0.01:1 to 10:1. If the content of the catalyst inhibitor is too low relative to the content of the urethane catalyst (E), the pot life tends to be short and the coating properties tend to decrease, and if it is too high, the curing speed tends to decrease.

[0105] <Other additives> In the adhesive composition of the present invention, in addition to the polyester resin (A), polyoxyalkylene polyol (B), hydrolysis inhibitor (C), crosslinking agent (D), urethane catalyst (E), etc., other additives may be blended as long as they do 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, tackifiers, etc.; other examples include inorganic or organic fillers, metal powders, pigments, and other powdered or particulate additives, and one of these can be used alone or in combination of two or more.

[0106] Furthermore, the adhesive composition of the present invention may also contain small amounts of impurities, etc., that are included in the raw materials for the production of the components of the adhesive composition, in addition to the additives mentioned above.

[0107] Such adhesive compositions can be prepared, for example, by preparing the above-mentioned polyester resin (A), polyoxyalkylene polyol (B), hydrolysis inhibitor (C), and any necessary optional components, and then blending and dispersing them during the production of the polyester resin (A), or by blending and dispersing them in a solution of the polyester resin (A) dissolved in an organic solvent.

[0108] The adhesive according to the present invention consists of the above-mentioned adhesive composition, that is, the adhesive composition is crosslinked (cured), and is generally formed as an adhesive layer by coating the adhesive composition onto a substrate or release sheet and drying it. An example of an application of the adhesive according to the present invention is shown below in the form of an adhesive sheet.

[0109] <Adhesive sheet> The adhesive sheet of the present invention has an adhesive layer containing the above-mentioned polyester-based adhesive, and may be an adhesive sheet having an adhesive layer on at least one side of a substrate, i.e., one side and / or both sides of the substrate, or it may be a substrate-less type substrate-less double-sided adhesive sheet. Furthermore, the adhesive sheet of the present invention is particularly suitable as an adhesive sheet for optical components used for bonding optical components. In this specification, "sheet" includes "film" and "tape."

[0110] The above adhesive sheet can be manufactured, for example, as follows. The adhesive sheet can be manufactured according to a known general method for manufacturing adhesive sheets. For example, the adhesive composition can be applied to one side of a substrate, dried to form an adhesive layer, a release sheet can be attached to its surface (the side opposite to the side in contact with the substrate), and cured as necessary to obtain the adhesive sheet of the present invention, which has a substrate and an adhesive layer, with the adhesive layer provided on at least one side of the substrate.

[0111] Alternatively, the adhesive sheet of the present invention can be obtained by applying the above adhesive composition onto a release sheet, drying it to form an adhesive layer, laminating a substrate to its surface (the side opposite to the surface in contact with the release sheet), and curing it as necessary.

[0112] Furthermore, by forming an adhesive layer on a release sheet and bonding another release sheet to its surface (the side opposite to the surface in contact with the release sheet), a substrate-less type of substrate-less double-sided adhesive sheet can be manufactured.

[0113] When using the resulting adhesive sheet or substrate-less double-sided adhesive sheet, the release sheet is peeled off from the adhesive layer and the adhesive layer is bonded to the adherend.

[0114] Examples of the above-mentioned substrates include polyester resins such as polyethylene naphthalate, polyethylene terephthalate, polybutylene terephthalate, and polyethylene terephthalate / isophthalate copolymers; polyolefin resins such as polyethylene, polypropylene, and polymethylpentene; polyfluoroethylene resins such as polyvinyl fluoride, polyvinylidene fluoride, and polyfluoroethylene; polyamides such as nylon 6 and nylon 6,6; vinyl polymers such as polyvinyl chloride, polyvinyl chloride / vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, 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; synthetic resin sheets made of polystyrene, polycarbonate, polyarylate, polyimide, polyurethane, and cycloolefin polymers; metal foils such as aluminum, copper, and iron; paper such as fine paper and glassine paper; and woven and nonwoven fabrics made of glass fibers, natural fibers, and synthetic fibers. These substrates can be used as single layers or as multi-layered structures made by laminating two or more types together.

[0115] Among these, substrates made of polyethylene terephthalate, polyimide, and polyurethane are particularly preferred, and polyethylene terephthalate is especially preferred because of its excellent adhesion to adhesives.

[0116] As the release sheet mentioned above, for example, various synthetic resin sheets, paper, cloth, nonwoven fabrics, etc., as exemplified in the above-mentioned base material, can be used, which have been treated with a release agent. In particular, it is preferable to use a silicone-based release sheet.

[0117] The thickness of the above-mentioned substrate is preferably, for example, 1 to 1000 μm, more preferably 2 to 500 μm, and even more preferably 3 to 300 μm.

[0118] For example, a gravure roll coater, reverse roll coater, kiss roll coater, dip roll coater, bar coater, knife coater, spray coater, comma coater, etc., can be used as a coating method for the above adhesive composition.

[0119] The drying conditions after coating with the above adhesive composition are preferably a drying temperature of 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.

[0120] The conditions for the curing treatment described above are typically a temperature of room temperature (23°C) to 70°C, and a duration of typically 1 to 30 days. Specifically, it can be carried out under conditions such as 1 to 20 days at 23°C, preferably 3 to 14 days at 23°C, or 1 to 10 days at 40°C.

[0121] The thickness of the adhesive layer of the above-mentioned adhesive sheet and substrate-less double-sided adhesive sheet is preferably 1 to 500 μm, more preferably 5 to 300 μm, and even more preferably 10 to 200 μm. If the thickness of the adhesive layer is too thin, the adhesive strength tends to decrease, and if it is too thick, it becomes difficult to apply uniformly, and defects such as air bubbles in the coating film tend to occur. When considering shock absorption, it is preferable to have a thickness of 50 μm or more.

[0122] The thickness of the adhesive layer is determined by using a digital indicator (Mitutoyo ID-C112B) to subtract the measured thickness of the components other than the adhesive layer from the measured thickness of the entire adhesive sheet.

[0123] Regarding the gel fraction of the adhesive layer described above, from the viewpoint of durability and adhesive strength, it is preferably 5% by weight or more, more preferably 10 to 95% by weight, even more preferably 20 to 90% by weight, particularly preferably 30 to 85% by weight, and especially preferably 40 to 80%. If the gel fraction is too low, the cohesive force tends to decrease, which tends to reduce durability. If the gel fraction is too high, there is a concern that the adhesive strength will decrease.

[0124] The gel fraction mentioned above is an indicator of the degree of crosslinking and can be calculated, for example, by the following method: An adhesive sheet (without a separator) consisting of a polymer sheet (e.g., PET film) with an adhesive layer formed on it is wrapped in a 200-mesh stainless steel wire mesh and immersed in toluene at 23°C for 24 hours. The gel fraction is defined as the weight percentage of the insoluble adhesive component remaining in the wire mesh after immersion, relative to the weight of the adhesive component before immersion. However, the weight of the base material is subtracted.

[0125] Furthermore, such adhesive sheets may be provided with a release sheet on the outside of the adhesive layer as needed to protect the adhesive layer. In addition, in adhesive sheets where the adhesive layer is formed on one side of the substrate, it is also possible to protect the adhesive layer by applying a release treatment to the side of the substrate opposite to the adhesive layer, thereby bringing the adhesive layer into contact with this release treatment surface.

[0126] <Optical component with adhesive layer> Furthermore, while the adhesive of the present invention can be used for bonding various components, it is particularly preferable to use it as an adhesive for optical components for bonding optical components, given its excellent optical properties and superior resistance to heat whitening under high temperature and high humidity conditions. By laminating an adhesive layer of such an adhesive composition onto an optical component, an optical component with an adhesive layer according to the present invention, having both an adhesive layer and an optical component, can be prepared.

[0127] In the optical member with the adhesive layer described above, it is preferable to provide a release film on the side of the adhesive layer opposite to the optical member surface. When putting it into practical use, the release film is peeled off and the adhesive layer and the adherend are bonded together. It is preferable to use a silicone-based release film for this purpose. [Examples]

[0128] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the invention. In the examples, "parts" and "%" refer to weight unless otherwise specified. Furthermore, 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 method described above.

[0129] The following ingredients were prepared.

[0130] [Manufacturing of polyester resins] The molar percentages of each polycarboxylic acid component described in the following manufacturing examples represent the molar ratio when the total amount of polycarboxylic acids is set to 100 mol%. Furthermore, the molar percentages of each polyol component described in the following manufacturing examples represent the molar ratio when the total amount of polyols is set to 100 mol%.

[0131] [Polyester resin (A-1)] In a reaction vessel equipped with a heating device, thermometer, stirrer, rectification column, nitrogen inlet tube, and vacuum device, 96 parts isophthalic acid and 468 parts sebacic acid were charged as polycarboxylic acids (a1), 271 parts neopentyl glycol, 130 parts 1,4-butanediol, 3 parts 1,6-hexanediol, and 5 parts trimethylolpropane were charged as polyols (a2), and 0.1 parts zinc acetate was charged as a catalyst. The temperature was gradually raised to 250°C and the esterification reaction was carried out over 4 hours. Subsequently, 0.05 parts tetrabutyl titanate was charged as a catalyst, the temperature was raised to 260°C, the pressure was reduced to 1.33 hPa, and the polycondensation reaction was carried out over 3 hours to obtain polyester resin (A-1). The obtained 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 are shown in Table 2 below. Furthermore, the resulting component ratios were as follows: polycarboxylic acids (a1) = isophthalic acid / sebacic acid = 20 mol% / 80 mol%; polyols (a2) = neopentyl glycol / 1,4-butanediol / 1,6-hexanediol / trimethylolpropane = 58.5 mol% / 34 mol% / 6.2 mol% / 1.3 mol%.

[0132] Table 1 shows the resin composition (structural units derived from the components) of the polyester resin (A-1) obtained above, and Table 2 shows its various physical properties. The abbreviations in Table 1 are 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)

[0133] [Polyoxyalkylene polyol (B)] (B-1) Polyethylene glycol (manufactured by Sanyo Chemical Industries, Ltd., "PEG600") Number average molecular weight 600 (B-2) Polyethylene glycol (manufactured by Sanyo Chemical Industries, Ltd., "PEG1000") Number average molecular weight 1000 (B-3) Polyethylene glycol (manufactured by Sanyo Chemical Industries, Ltd., "PEG2000") Number average molecular weight 2000

[0134] [Hydrolysis inhibitor (C)] (C-1): Polyvalent carbodiimide compound (Nisshinbo Chemical Co., Ltd., "Carbodilite (registered trademark) V-09GB")

[0135] [Crosslinking agent (D)] (D-1): Trimethylolpropane / tolide diisocyanate adduct (manufactured by Tosoh Corporation, "Coronate L55E")

[0136] [Urethane catalyst (E)] (E-1): Zirconium-based compound diluted to a solid content of 1% with acetylacetone (Matsumoto Fine Chemical Co., Ltd., "Orgatics ZC-150")

[0137] (Example 1) The polyester resin (A-1) obtained above was diluted with ethyl acetate to a solid content concentration of 50%. To this polyester resin (A-1) (100 parts as solid content), 2 parts of polyoxyalkylene polyol (B-1), 1 part of hydrolysis inhibitor (C-1), 3.0 parts (solid content) of crosslinking agent (D-1), and 0.02 parts (solid content) of urethane catalyst (E-1) were added, and the mixture was stirred and mixed to obtain an adhesive composition.

[0138] (Example 2) An adhesive composition was obtained in the same manner as in Example 1, except that 2 parts of polyoxyalkylene polyol (B-1) was changed to 1 part of (B-2) and 3.0 parts of crosslinking agent (D-1) was changed to 2.2 parts.

[0139] (Example 3) An adhesive composition was obtained in the same manner as in Example 1, except that 2 parts of polyoxyalkylene polyol (B-1) was changed to 1 part of (B-3), and the amount of crosslinking agent (D-1) was changed from 3.0 parts to 2.0 parts.

[0140] (Comparative Example 1) An adhesive composition was obtained in the same manner as in Example 1, except that polyoxyalkylene polyol (B-1) was not included and the amount of crosslinking agent (D-1) was changed from 3.0 parts to 1.8 parts.

[0141] (Comparative Example 2) An adhesive composition was obtained in the same manner as in Example 1, except that 2 parts of polyoxyalkylene polyol (B-1) was changed to 15 parts of (B-3), and the amount of crosslinking agent (D-1) was changed from 3.0 parts to 12.0 parts.

[0142] Using the adhesive compositions obtained in the above examples and comparative examples, adhesive sheets were prepared and evaluated as described below. The results are summarized in Tables 3 and 4.

[0143] <Preparation of adhesive sheets with single-sided release film> The polyester-based adhesive compositions obtained in Examples 1-3 and Comparative Examples 1-2 were applied to a 100 μm thick PET film (Toray Industries, Ltd., "Lumirror T100") using an applicator, and dried at 120°C for 4 minutes to obtain an adhesive sheet with a PET film and an adhesive composition layer thickness of 50 μm. Next, 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 Co., Ltd., SP-PET-01-BU), and aged at 40°C for 4 days to obtain an adhesive sheet with a single-sided release film.

[0144] [Gel fraction] The adhesive sheet obtained above was wrapped in a 200-mesh stainless steel wire mesh and immersed in toluene at 23°C for 24 hours. The weight of the adhesive component before immersion and the weight of the insoluble adhesive component remaining in the wire mesh after immersion were measured, and the percentage was calculated using the following formula to determine the gel fraction (%). However, the weight of the base material was subtracted. Weight of insoluble adhesive component remaining in the wire mesh after immersion / Weight of adhesive component before immersion × 100 (%)

[0145] (Evaluation of adhesive sheets) "Evaluation of adhesive strength" [Initial adhesive strength (adhesive strength)] The single-sided release film adhesive sheet obtained above was cut to a size of 25 mm x 200 mm in an environment of 23°C and 50% RH. After peeling off the release film, the adhesive layer side was pressed onto polycarbonate (PC) and alkali-free glass (Corning Eagle XG) by rolling a 2 kg roller back and forth twice. After leaving it in the same atmosphere for 30 minutes, the degree of peel at 180 degrees (N / 25 mm) was measured using an Autograph (Shimadzu Corporation, "Autograph AG-X 50N") at a peeling speed of 300 mm / min. The evaluation criteria are as follows.

[0146] (Evaluation criteria: Compared to polycarbonate (PC)) ◎···Larger than 15N / 25mm ○...Greater than 10N / 25mm and less than or equal to 15N / 25mm △···Larger than 3N / 25mm and 10N / 25mm or less ×...3N / 25mm or less

[0147] (Evaluation criteria: Against alkali-free glass) ◎...5N / 25mm or more ○···3N / 25mm or more, less than 5N / 25mm △···1N / 25mm or more, less than 3N / 25mm ×···1N / less than 25mm

[0148] "Optical properties evaluation" [Initial Haze] The adhesive sheet with single-sided release film obtained above was cut to a size of 30 mm x 50 mm in an environment of 23°C and 50% RH. After peeling off the release film, the adhesive layer side was pressed onto alkali-free glass (Corning Eagle XG) by rolling a 2 kg roller back and forth twice, and then autoclaved (50°C, 0.5 MPa, 20 minutes) to produce a test specimen having the structure of PET film / adhesive layer / alkali-free glass plate. For the above test specimens, the haze was measured under conditions of 23°C and 50% RH using HAZE MATER NDH2000 (manufactured by Nippon Denshoku Industries Co., Ltd.).

[0149] (Evaluation Criteria) ◎···3.0% or less ○...Greater than 3.0% and less than or equal to 5.0% △···Greater than 5.0% and less than or equal to 10.0% ×···Greater than 10.0%

[0150] [Haze after moist heat test] The test specimens used in the initial haze measurement underwent a moist heat test at 85°C × 85%RH × 100 hours, and the haze 10 minutes after removal was evaluated in the same manner as the initial haze measurement.

[0151] [Haze displacement (resistance to moisture and heat whitening)] The haze displacement before and after the moist heat test was evaluated according to the following criteria. Haze displacement (%) = Haze value after moist heat test (%) - Initial haze value (%) ◎···Haze displacement less than 2% ○···Haze displacement 2% or more, less than 5% △···Haze displacement of 5% or more, less than 10% ×...Haze displacement of 10% or more

[0152] [Table 1]

[0153] [Table 2]

[0154] [Table 3]

[0155] [Table 4]

[0156] The results shown in Tables 3 and 4 above indicate that the adhesive sheets obtained from the adhesive compositions of Examples 1 to 3 exhibit excellent initial adhesive strength and resistance to moisture-induced whitening. In contrast, the adhesive sheet obtained from the adhesive composition of Comparative Example 1 had excellent initial adhesive strength, but because it did not contain polyoxyalkylene polyol (B), it had poor resistance to moisture and heat whitening. In Comparative Example 2, the high content of polyoxyalkylene polyol (B) resulted in inferiority in both the initial haze and the haze after the moist heat test. This also indicates that an adhesive composition containing a polyester resin (A), a polyoxyalkylene polyol (B), and a hydrolysis inhibitor (C), wherein the polyoxyalkylene polyol (B) is present in an amount of 0.01 to 10 parts by weight per 100 parts by weight of the polyester resin (A), exhibits excellent adhesive properties. [Industrial applicability]

[0157] The polyester adhesive composition of the present invention exhibits excellent initial tackiness, optical properties, and resistance to moisture and heat whitening. Therefore, adhesives and adhesive sheets using this composition can be used for bonding optical components, particularly for shatterproof films for glass and resin glass.

Claims

1. A polyester adhesive composition containing a polyester resin (A), a polyoxyalkylene polyol (B), and a hydrolysis inhibitor (C), The content of the polyoxyalkylene polyol (B) is 0.01 to 10 parts by weight per 100 parts by weight of the polyester resin (A). A polyester-based adhesive composition characterized in that the polyoxyalkylene polyol (B) contains structural units derived from ethylene oxide.

2. The polyester adhesive composition according to claim 1, characterized in that the polyester resin (A) contains structural units derived from polycarboxylic acids (a1) and structural units derived from polyols (a2).

3. The polyester adhesive composition according to claim 1 or 2, characterized in that the ester bond concentration of the polyester resin (A) is 2 to 11.5 mmol / g.

4. The polyester-based adhesive composition according to any one of claims 1 to 3, characterized in that the number average molecular weight of the polyoxyalkylene polyol (B) is 450 to 20,000.

5. The polyester adhesive composition according to any one of claims 1 to 4, characterized in that the hydrolysis inhibitor (C) contains a carbodiimide group-containing compound and / or an oxazoline group-containing compound.

6. The polyester adhesive composition according to any one of claims 1 to 5, characterized in that it contains 0.01 to 10 parts by weight of the hydrolysis inhibitor (C) per 100 parts by weight of the polyester resin (A).

7. The polyester adhesive composition according to any one of claims 1 to 6, further characterized by containing 0.01 to 15 parts by weight of a crosslinking agent (D) per 100 parts by weight of polyester resin (A).

8. The polyester adhesive composition according to any one of claims 1, 2, 4 to 7, characterized in that the ester bond concentration of the polyester resin (A) is 3.5 to 15 mmol / g.

9. The polyester adhesive composition according to any one of claims 1 to 8, characterized in that the content of the polyoxyalkylene polyol (B) is 0.01 to 5 parts by weight per 100 parts by weight of the polyester resin (A).

10. The polyester adhesive composition according to any one of claims 1 to 9, characterized in that the weight-average molecular weight of the polyester resin (A) is 40,000 to 120,000.

11. A polyester adhesive characterized in that the polyester adhesive composition described in any one of claims 1 to 10 is crosslinked.

12. An adhesive sheet characterized by having an adhesive layer containing the polyester-based adhesive described in claim 11.

13. The adhesive sheet according to claim 12, characterized in that it is a substrate-less type that does not have a base material.

14. The adhesive sheet according to claim 12, characterized in that the adhesive layer is formed on at least one side of the substrate.

15. An adhesive sheet according to any one of claims 12 to 14, characterized in that it is used for bonding optical components.

16. An optical member with an adhesive layer, comprising an adhesive layer and an optical member, wherein the adhesive layer contains the polyester adhesive described in claim 11.

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