Polyester-based pressure-sensitive adhesive composition, pressure-sensitive adhesive, pressure-sensitive adhesive sheet, and optical member with pressure-sensitive adhesive layer

Abstract

To provide: a polyester-based adhesive composition which causes less yellowing and has excellent ultraviolet absorbency while having excellent adhesive strength and substrate adhesiveness; an adhesive, a pressure-sensitive adhesive sheet; and an optical member with an adhesive layer.SOLUTION: There is provided a polyester-based adhesive composition which comprises a polyester-based resin [I] containing a structural unit derived from polycarboxylic acids (A) and a structural unit derived from a polyol (B) and an ultraviolet absorber [II], wherein the ultraviolet absorber (II) is at least one selected from a triazine-based compound, a triazole-based compound and a cyanoacrylate-based compound.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polyester-based pressure-sensitive adhesive composition, a pressure-sensitive adhesive, a pressure-sensitive adhesive sheet, and an optical component with a pressure-sensitive adhesive layer, and more particularly to a polyester-based pressure-sensitive adhesive composition, a pressure-sensitive adhesive, a pressure-sensitive adhesive sheet, and an optical component with a pressure-sensitive adhesive layer that are excellent in adhesive strength and substrate adhesion, while also exhibiting little yellowing and excellent ultraviolet absorption ability. [Background technology]

[0002] Image display devices such as plasma displays (PDPs), liquid crystal displays (LCDs), organic light-emitting diode displays (OLEDs), electrophoretic displays (EPDs), and interferometric modulation displays (IMODs) are composed of various components, and adhesives or adhesive sheets are used to bond and integrate these components for image display devices. For example, in touch panel displays, components for image display devices such as surface protection panels, touch panels, and image display panels are used, and adhesives or adhesive sheets are used to laminate these components.

[0003] For example, Patent Document 1 discloses a transparent adhesive sheet for bonding a surface protective layer or a touch panel in an image display device to a display surface of an image display unit, or a transparent adhesive sheet for bonding a surface protective layer and a touch panel, which comprises (A) a (meth)acrylic acid alkyl ester having 4 to 18 carbon atoms in the alkyl group, (B) a polar monomer having a homopolymer glass transition temperature (Tg) of 50°C or higher, and (C) a copolymer of monomers containing a (meth)acrylic acid ester represented by a specific formula or a hydrophilic monomer having a homopolymer glass transition temperature (Tg) of 10°C or lower, and which has a tan δ of 0.13 or higher at 140°C and 1.0 Hz and a storage modulus of 8.9 × 10 at 25°C and 1.0 Hz. 4 A transparent adhesive sheet with a viscosity of 100 MPa or less has been proposed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-163591 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the technology disclosed in Patent Document 1 and the pressure-sensitive adhesives that have been studied to date are acrylic pressure-sensitive adhesives containing acrylic resins, and these acrylic pressure-sensitive adhesives require improvement in terms of impact resistance because the acrylic resin itself is soft. However, designing the acrylic resin to be hard in order to impart impact resistance results in a decrease in adhesive strength and a decrease in adhesion to substrates.

[0006] In recent years, with the trend toward lighter and thinner displays, new technologies have been proposed, including the in-cell method, in which touch panel electrodes are integrated into the LCD pixels, and the on-cell method, in which electrodes are directly attached to the glass substrate or protective panel of the LCD module to provide touch panel functionality. Furthermore, new configurations have been proposed that integrate touch panel functionality, previously achieved through lamination, directly into the LCD module (also known as the "touch-on-lens method"). In these in-cell, on-cell, and touch-on-lens configurations, a single adhesive is used to attach the surface protection panel to the LCD module. This requires a single adhesive sheet or adhesive to achieve the functions required for both the attachment of the surface protection panel and the LCD module, creating a demand for greater functionality than ever before. In particular, display module manufacturers are expected to incorporate optical functions, such as polarizing films and retardation films, directly into the LCD module and other components, in addition to touch panels, thereby minimizing the number of components. As functional layers, such as functional films, are simplified and module configurations change, adhesive sheets must also have UV protection to protect these functional layers.

[0007] Therefore, under these circumstances, the present invention aims to provide a polyester-based pressure-sensitive adhesive composition that uses a polyester-based resin as a pressure-sensitive adhesive instead of an acrylic-based resin, and that has excellent adhesive strength and adhesion to substrates, as well as little yellowing and excellent ultraviolet absorption ability, and further aims to provide a pressure-sensitive adhesive, a pressure-sensitive adhesive sheet, and an optical component with a pressure-sensitive adhesive layer. [Means for solving the problem]

[0008] However, in view of the above circumstances, the present inventors have conducted extensive research and have found that by adding a specific ultraviolet absorber to a pressure-sensitive adhesive composition containing a polyester resin, it is possible to obtain a polyester-based pressure-sensitive adhesive composition that is excellent in adhesive strength and substrate adhesion, is less prone to yellowing, and has excellent ultraviolet absorption ability, and have completed the present invention.

[0009] That is, a first aspect of the present invention is a polyester-based pressure-sensitive adhesive composition comprising a polyester-based resin [I] containing structural units derived from a polycarboxylic acid (A) and structural units derived from a polyol (B), and an ultraviolet absorber [II], wherein the ultraviolet absorber [II] is at least one selected from the group consisting of a triazine-based compound, a triazole-based compound, and a cyanoacrylate-based compound.

[0010] In addition, a second aspect of the present invention is a pressure-sensitive adhesive obtained by crosslinking the polyester-based pressure-sensitive adhesive composition, a third aspect is a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive, and a fourth aspect is an optical member with a pressure-sensitive adhesive layer having a pressure-sensitive adhesive layer and an optical member, wherein the pressure-sensitive adhesive layer contains the pressure-sensitive adhesive.

[0011] In the present invention, it is not the case that any UV absorber can be used as the UV absorber to be incorporated into the polyester resin, but it has been found that limited specific UV absorbers work well in combination with polyester resins. Normally, a benzophenone-based compound UV absorber is used because of its excellent ability to absorb UV rays in the long wavelength region. However, by deliberately incorporating a UV absorber that is at least one selected from a triazine-based compound, a triazole-based compound, and a cyanoacrylate-based compound rather than a benzophenone-based compound, it has surprisingly not impaired adhesive strength, has excellent UV absorption in the long wavelength region, and also has excellent yellowing resistance, thereby achieving the object of the present invention. [Effects of the Invention]

[0012] The polyester-based pressure-sensitive adhesive composition of the present invention contains a polyester-based resin [I] containing structural units derived from a polycarboxylic acid (A) and structural units derived from a polyol (B), and an ultraviolet absorber [II], wherein the ultraviolet absorber [II] is at least one selected from triazine compounds, triazole compounds, and cyanoacrylate compounds. Therefore, the polyester-based pressure-sensitive adhesive composition has excellent adhesive strength and substrate adhesion, minimal yellowing, and excellent ultraviolet absorption ability, and is particularly useful as a pressure-sensitive adhesive for optical members. DETAILED DESCRIPTION OF THE INVENTION

[0013] The configuration of the present invention will be described in detail below, but these are merely examples of preferred embodiments. In the present invention, the term "carboxylic acids" includes not only carboxylic acids but also carboxylic acid derivatives such as carboxylic acid salts, carboxylic acid anhydrides, carboxylic acid halides, and carboxylic acid esters.

[0014] The polyester-based pressure-sensitive adhesive composition of the present invention (hereinafter sometimes referred to as "pressure-sensitive adhesive composition") is characterized by containing a polyester-based resin [I] and a specific ultraviolet absorber [II]. The pressure-sensitive adhesive composition of the present invention contains the polyester-based resin [I] and the specific ultraviolet absorber [II] as essential components, and preferably contains at least one of a hydrolysis inhibitor [III] and a crosslinking agent [IV], and more preferably contains both the hydrolysis inhibitor [III] and the crosslinking agent [IV]. Each component constituting the pressure-sensitive adhesive composition of the present invention will be explained below in order.

[0015] <Polyester resin [I]> The polyester resin [I] is usually obtained by copolymerizing copolymerization components containing polycarboxylic acids (A) and polyol (B) as constituent raw materials, and the polyester resin [I] has structural units derived from the polycarboxylic acids (A) and structural units derived from the polyol (B) as its resin composition.

[0016] [Polycarboxylic acids (A)] Examples of the polycarboxylic acids (A) used as constituent raw materials for the polyester resin [I] include dicarboxylic acids and tricarboxylic or higher polycarboxylic acids, and dicarboxylic acids are preferably used since they allow the polyester resin [I] to be obtained stably.

[0017] Examples of the dicarboxylic acids include aliphatic dicarboxylic acids such as malonic acids, dimethylmalonic acids, succinic acids, glutaric acids, adipic acids, trimethyladipic acids, pimelic 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 such as 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; etc. Examples of the trivalent or higher polyvalent carboxylic acids include trimellitic acids, pyromellitic acids, adamantanetricarboxylic acids, and trimesic acids. These polycarboxylic acids (A) can be used alone or in combination of two or more kinds.

[0018] Among the polycarboxylic acids (A), aromatic polycarboxylic acids, particularly asymmetric aromatic dicarboxylic acids (A-1), are preferably contained in order to reduce the crystallinity of the polyester resin [I]. Examples of the asymmetric aromatic dicarboxylic acids (A-1) include phthalic acids, isophthalic acids, 1,8-naphthalenedicarboxylic acids, 2,3-naphthalenedicarboxylic acids, and 2,7-naphthalenedicarboxylic acids. Among these, isophthalic acids are particularly preferred in terms of reactivity.

[0019] The content of such aromatic polycarboxylic acids, particularly asymmetric aromatic dicarboxylic acids (A-1), is preferably 1 to 90 mol%, particularly preferably 5 to 80 mol%, further preferably 10 to 70 mol%, particularly preferably 15 to 60 mol%, and even more preferably 20 to 50 mol%, based on the total polycarboxylic acids (A). If the content is too low, the adhesive strength at high temperatures tends to decrease, the resin tends to crystallize, and sufficient adhesive performance tends to be lost, while if the content is too high, the initial adhesive strength (tack) tends to decrease.

[0020] In the present invention, from the viewpoint of improving initial adhesive strength (tack), it is preferable that the polyvalent carboxylic acid (A) contains an aliphatic dicarboxylic acid (A-2) having 4 or more carbon atoms (including the carbon atoms in the carboxy group), and it is particularly preferable that the polyvalent carboxylic acid (A) contains an aliphatic dicarboxylic acid having 6 to 12 carbon atoms (including the carbon atoms in the carboxy group), such as adipic acid, azelaic acid, or sebacic acid.

[0021] The content of the aliphatic dicarboxylic acids (A-2) having 4 or more carbon atoms is preferably 5 to 100 mol % relative to the total polycarboxylic acids (A). It is particularly preferably 20 to 95 mol %, particularly preferably 30 to 90 mol %, even more preferably 40 to 85 mol %, and especially preferably 50 to 80 mol %. If the content is too low, the glass transition temperature of the polyester resin [I] becomes too high, and sufficient adhesive strength tends to be insufficient. On the other hand, if the content is too high, adhesive strength at high temperatures tends to decrease, or the resin tends to crystallize, making it difficult to achieve sufficient adhesive performance.

[0022] In the present invention, from the viewpoint of adhesive properties, it is also preferable to use asymmetric aromatic dicarboxylic acids (A-1) and aliphatic dicarboxylic acids (A-2) having 4 or more carbon atoms in combination as the polycarboxylic acids (A). In this case, the content ratio (molar ratio) of the asymmetric aromatic dicarboxylic acids (A-1) to the aliphatic dicarboxylic acids (A-2) having 4 or more carbon atoms is preferably (A-1) / (A-2)=1 / 99 to 90 / 10, particularly preferably 10 / 90 to 70 / 30, and further preferably 20 / 80 to 60 / 40.

[0023] In the present invention, trivalent or higher polycarboxylic acids (A-3) can also be used to increase the number of branching points in the polyester resin [I]. Among these, trimellitic acids are preferably used because they are less likely to gel during production.

[0024] The content of the trivalent or higher polycarboxylic acids (A-3) is preferably 10 mol % or less, particularly preferably 0.1 to 5 mol %, based on the total amount of the polycarboxylic acids (A), in order to increase the cohesive strength when used as an adhesive. If the content is too high, gelation tends to occur during the production of the polyester resin [I].

[0025] [Polyol (B)] The polyol (B) used as a constituent material of the polyester resin [I] includes dihydric alcohols and trihydric or higher polyols.

[0026] Examples of the dihydric alcohol 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, tricyclodecane dimethanol, adamantanediol, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol; Examples of the aromatic diol include 4,4'-thiodiphenol, 4,4'-methylenediphenol, 4,4'-dihydroxybiphenyl, o-, m-, and p-dihydroxybenzene, 2,5-naphthalenediol, p-xylenediol, and their ethylene oxide adducts and propylene oxide adducts. Further examples include fatty acid esters derived from castor oil, dimer diols derived from oleic acid, erucic acid, and the like, and glycerol monostearate. Examples of the trihydric 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, and adamantanetriol. The above polyols (B) can be used alone or in combination of two or more kinds.

[0027] In the present invention, in order to lower the glass transition temperature (Tg) of the polyester resin [I] and improve the initial adhesive strength, it is preferable that the polyol (B) contains a linear aliphatic diol (B-1), more preferably a linear aliphatic diol having 2 to 18 carbon atoms, and particularly preferably ethylene glycol, 1,3-propanediol, or 1,4-butanediol.

[0028] The content of the linear aliphatic diol (B-1) relative to the total polyol (B) is preferably 1 to 100 mol%, more preferably 2 to 80 mol%, particularly preferably 3 to 70 mol%, further preferably 4 to 60 mol%, and particularly preferably 5 to 50 mol%. If the content is too low, it tends to be difficult to obtain stable resin formation.

[0029] Among the polyols (B), it is preferable to contain a diol (B-2) having a hydrocarbon group in the side chain, because it can disrupt the crystallinity. Examples of the diol (B-2) having a hydrocarbon group in the side chain include aliphatic diols having a branched structure, such as dipropylene glycol, 2,4-dimethyl-2-ethylhexane-1,3-diol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2-methyl-2-ethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 1,3-butanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,6-hexanediol, and dimer diol.

[0030] The content of the diol (B-2) having a hydrocarbon group in the side chain is preferably 5 to 100 mol % relative to the total polyol (B), particularly 20 to 90 mol %, and even more preferably 40 to 80 mol %. If the content is too low, the resin tends to crystallize, making it difficult to obtain sufficient adhesive properties. If the content is too high, the reaction time tends to be long in the production of the polyester resin [I].

[0031] Among the polyols (B), it is preferable to contain a diol (B-3) having an alicyclic structure, since it can disrupt the crystallinity and increase the elastic modulus. Examples of the diol (B-3) having an alicyclic structure include 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. Among these, 1,4-cyclohexanedimethanol is preferred from the viewpoint of reactivity.

[0032] The content of the diol (B-3) having an alicyclic structure is preferably 20 to 100 mol % of the total polyol (B), particularly 40 to 98 mol %, and even more preferably 60 to 95 mol %. If the content is too low, the resin tends to crystallize, making it difficult to obtain sufficient adhesive properties, and the elastic modulus tends to decrease, resulting in a decrease in impact resistance. If the content is too high, the reaction time tends to be longer in the production of the polyester resin [I].

[0033] Furthermore, in the present invention, it is preferable to use a trivalent or higher polyol (B-4) as the polyol (B) in order to form a reaction site with the crosslinking agent [IV] described below in the polyester resin [I] and increase the cohesive strength, and among these, it is preferable to use trimethylolpropane, trimethylolethane, glycerin, pentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, or 1,2,6-hexanetriol. Among these, it is particularly preferable to use trimethylolpropane because it is relatively less likely to form a gel.

[0034] The content of the trihydric or higher polyol (B-4) is preferably 20 mol % or less, more preferably 0.1 to 10 mol %, and particularly preferably 0.5 to 5 mol %, based on the total amount of the polyol (B). If the content of the trihydric or higher polyol is too high, it tends to be difficult to produce the polyester resin [I].

[0035] The polyester resin [I] used in the present invention is produced by appropriately selecting the above polyvalent carboxylic acids (A) and polyol (B) and subjecting them to a polycondensation reaction in the presence of a catalyst by a known method.

[0036] The blending ratio of the polycarboxylic acid (A) to the polyol (B) is preferably 1 to 2 equivalents, particularly preferably 1.1 to 1.7 equivalents, of the polyol (B) per equivalent of the polycarboxylic acid (A). If the blending ratio of the polyol (B) is too low, the acid value tends to be high, making it difficult to achieve a high molecular weight, while if it is too high, the yield tends to decrease.

[0037] In the polycondensation reaction, an esterification reaction is carried out first, and then the polycondensation reaction is carried out.

[0038] In such an esterification reaction, a catalyst is usually used, and specific 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 catalysts such as zinc acetate, manganese acetate, and dibutyltin oxide, and one or more of these are used. Among these, antimony trioxide, tetrabutyl titanate, germanium dioxide, and zinc acetate are preferred, with germanium dioxide being particularly preferred, in view of the balance between high catalytic activity and color.

[0039] The amount of the catalyst is preferably 1 to 10,000 ppm by weight, particularly preferably 10 to 5,000 ppm, and further preferably 20 to 3,000 ppm, based on the total weight of the copolymerization components. If the amount is too small, the polymerization reaction tends to proceed insufficiently, whereas if the amount is too large, there is no advantage such as shortening the reaction time, and side reactions tend to occur easily.

[0040] The reaction temperature during the esterification reaction is preferably 200 to 300°C, particularly preferably 210 to 280°C, and even more preferably 220 to 260°C. If the reaction temperature is too low, the reaction tends to proceed insufficiently, while if it is too high, side reactions such as decomposition tend to occur. The pressure during the reaction is usually normal pressure.

[0041] After the esterification reaction, a polycondensation reaction is carried out. As reaction conditions for the polycondensation reaction, it is preferable to further compound the same amount of the same catalyst as used in the above esterification reaction, set the reaction temperature at preferably 220 to 280°C, particularly preferably 230 to 270°C, and gradually reduce the pressure of the reaction system until the reaction is finally 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.

[0042] Thus, the polyester resin [I] used in the present invention is obtained.

[0043] The polyester resin [I] typically contains structural units derived from polycarboxylic acids (A) and polyols (B). When structural units derived from aromatic polycarboxylic acids, particularly asymmetric aromatic dicarboxylic acids (A-1), are included as structural units derived from polycarboxylic acids (A), the structural units derived from asymmetric aromatic dicarboxylic acids (A-1) preferably account for 1 to 90 mol %, particularly preferably 5 to 80 mol %, more preferably 10 to 70 mol %, even more preferably 15 to 60 mol %, and especially preferably 20 to 50 mol % of the structural units derived from polycarboxylic acids (A). If the content is too low, the adhesive strength at high temperatures tends to decrease or the resin crystallizes, resulting in insufficient adhesive performance. If the content is too high, the initial adhesive strength (tack) tends to decrease.

[0044] When the structural units derived from the aliphatic dicarboxylic acids (A-2) having 4 or more carbon atoms are contained as structural units derived from the polycarboxylic acids (A), the structural units derived from the aliphatic dicarboxylic acids (A-2) having 4 or more carbon atoms preferably account for 5 to 100 mol %, more preferably 20 to 95 mol %, more preferably 30 to 90 mol %, particularly preferably 40 to 85 mol %, and especially preferably 50 to 80 mol % of the structural units derived from the polycarboxylic acids (A). If this content ratio is too low, the glass transition temperature of the polyester resin [I] tends to be too high, making it difficult to obtain sufficient adhesive strength. However, if this content ratio is too high, the adhesive strength at high temperatures tends to decrease, or the resin tends to crystallize, making it difficult to obtain sufficient adhesive performance.

[0045] When the structural units derived from the trivalent or higher polycarboxylic acid (A-3) are contained as structural units derived from the polycarboxylic acid (A), the structural units derived from the trivalent or higher polycarboxylic acid (A-3) preferably account for 10 mol % or less, more preferably 0.1 to 5 mol %, of the structural units derived from the polycarboxylic acid (A). If this content is too high, gelation tends to occur during the production of the polyester resin [I].

[0046] Furthermore, when the structural units derived from the linear aliphatic diol (B-1) are contained as structural units derived from the polyol (B), the structural units derived from the linear aliphatic diol (B-1) preferably account for 1 to 100 mol %, more preferably 2 to 80 mol %, even more preferably 3 to 70 mol %, particularly preferably 4 to 60 mol %, and especially preferably 5 to 50 mol % of the structural units derived from the polyol (B). If this content ratio is too low, the reactivity of the polyester resin [I] during production tends to decrease. However, if this content ratio is too high, the polyester resin [I] tends to crystallize, resulting in a decrease in the initial adhesive strength of the adhesive.

[0047] On the other hand, when the structural units derived from the diol (B-2) having a hydrocarbon group in the side chain are contained as structural units derived from the polyol (B), the structural units derived from the diol (B-2) having a hydrocarbon group in the side chain preferably account for 5 to 100 mol %, particularly 20 to 90 mol %, and even more preferably 40 to 80 mol % of the structural units derived from the polyol (B). If this content ratio is too low, the polyester-based resin [I] tends to crystallize, and the initial adhesive strength of the adhesive tends to decrease. However, if this content ratio is too high, the reactivity of the polyester-based resin [I] during production tends to decrease.

[0048] Furthermore, when the structural units derived from the diol (B-3) having an alicyclic structure are contained as structural units derived from the polyol (B), the structural units derived from the diol (B-3) having an alicyclic structure preferably account for 20 to 100 mol %, particularly 40 to 98 mol %, and even more preferably 60 to 95 mol % of the structural units derived from the polyol (B). If this content ratio is too low, the resin tends to crystallize, making it difficult to obtain sufficient adhesive performance, and the elastic modulus tends to decrease, resulting in reduced impact resistance. However, if this content ratio is too high, the reaction time tends to be longer in the production of the polyester resin [I].

[0049] When the structural units derived from the trihydric or higher polyol (B-4) are contained as structural units derived from the polyol (B), the structural units derived from the trihydric or higher polyol (B-4) preferably account for 10 mol % or less, more preferably 0.1 to 5 mol %, of the structural units derived from the polyol (B). If the content is too high, the polyester resin [I] tends to gel during production, making production difficult.

[0050] Here, the proportion of structural units (compositional proportion) derived from each component of the polyester resin [I] can be determined, for example, by NMR.

[0051] The glass transition temperature (Tg) of the polyester resin [I], from the viewpoint of adhesive properties, is −70 to 20° C., preferably −60 to 10° C., more preferably −50 to 0° C., particularly preferably −40 to −5° C., and especially preferably −30 to −10° C. If the glass transition temperature (Tg) is too high, flexibility will be lost, initial adhesive strength will decrease, adhesive strength will not be exerted easily with pressure of the order of finger pressure, and workability will tend to decrease, whereas if the glass transition temperature (Tg) is too low, cohesive strength will decrease, and the adhesive sheet will be prone to deformation, tending to impair appearance.

[0052] Here, the glass transition temperature (Tg) of the polyester resin [I] is a value measured using a differential scanning calorimeter DSC Q20 manufactured by TA Instruments. The measurement temperature range is −90 to 100° C., and the temperature rise rate is 10° C. / min.

[0053] The weight-average molecular weight of the polyester resin [I] is 5,000 to 300,000 in terms of the cohesive strength of the adhesive. It is preferably 8,000 to 200,000, particularly preferably 10,000 to 150,000, and even more preferably 20,000 to 100,000. If the weight-average molecular weight is too small, the adhesive will not have sufficient cohesive strength, and heat resistance and mechanical strength tend to be reduced. If the weight-average molecular weight is too large, the polyester resin [I] is more likely to gel during production, making it difficult to obtain the resin, and further, adhesion to the substrate tends to be reduced.

[0054] The weight-average molecular weight in the present invention is a weight-average molecular weight converted into a standard polystyrene molecular weight, and is measured using a high-performance liquid chromatograph (Waters, "ACQUITY APC System") equipped with four columns in series: one ACQUITY APC XT 450, one ACQUITY APC XT 200, and two ACQUITY APC XT 45 columns.

[0055] The acid value of the polyester resin [I] is preferably 10 mgKOH / g or less, particularly 3 mgKOH / g or less, and more preferably 1 mgKOH / g or less. If the acid value is too high, hydrolysis tends to proceed more easily, and when a layer of metal or the like is attached to one side of the pressure-sensitive adhesive layer, corrosion tends to occur. For example, when a metal oxide thin film layer is formed, corrosion tends to occur, and the conductivity of the metal oxide thin film tends to decrease.

[0056] The acid value of the polyester resin [I] is determined by neutralization titration in accordance with JIS K 0070.

[0057] <Ultraviolet absorber [II]> The pressure-sensitive adhesive composition of the present invention contains the polyester resin [I] and a specific ultraviolet absorber [II]. By containing the polyester resin [I] and the specific ultraviolet absorber [II], the pressure-sensitive adhesive composition of the present invention exhibits the effects of excellent adhesive strength and substrate adhesion, little yellowing, and excellent ultraviolet absorption ability. In the case of an acrylic resin that is commonly used as a pressure-sensitive adhesive composition, even if the acrylic pressure-sensitive adhesive composition contains the above-mentioned specific UV absorber [II], not all of the above-mentioned effects are achieved. The present invention has discovered that the above-mentioned effects, particularly excellent effects in yellowing resistance and UV absorption ability, can be achieved by selectively combining a polyester resin with the above-mentioned specific UV absorber.

[0058] The specific ultraviolet absorber [II] may be at least one selected from the group consisting of triazine compounds, triazole compounds, and cyanoacrylate compounds.

[0059] Examples of the triazine compounds include 2-(2-hydroxy-4-methoxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2-(2-hydroxy-4-ethoxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2-(2-hydroxy-4-propoxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2-(2-hydroxy-4-butoxyphenyl)-4,6-diphenyl-1,3,5-triazine, and 2-(2-hydroxy-4-hexyloxyphenyl)-4,6-diphenyl-1,3,5-triazine. azine, 2-(2-hydroxy-4-octyloxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2-(2-hydroxy-4-dodecyloxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2-(2-hydroxy-4-benzyloxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2,4-bis(2-hydroxy-4-butoxyphenyl)-6-(2,4-dibutoxyphenyl)-1,3-5-triazine, 2,4,6-tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-1,3 ,5-triazine, 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine, 2-[4-[(2-hydroxy-3-dodecyloxypropyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-[4-[(2-hydroxy-3-tridecyloxypropyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-[4-[ (2-hydroxy-3-(2'-ethyl)hexyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2,4-bis(2,4-dimethylphenyl)-6-[2-hydroxy-4-(3-octyloxy-2-hydroxypropyloxy)-5-α-cumylphenyl]-s-triazine, 2,4-bis(2,4-dimethylphenyl)-6-[2-hydroxy-4-(3-nonyloxy-2-hydroxypropyloxy)-5-α-cumylphenyl]-s-triazine 2,4-bis(2,Examples of suitable hydroxyphenyl triazines include hydroxyphenyl triazines such as 2-(2-hydroxy-4-(3-decyloxy-2-hydroxypropyloxy)-5-α-cumylphenyl)-s-triazine and 2-(2-hydroxy-4-acryloyloxyethoxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine. These may be used alone or in combination of two or more. Of these, 2,4-bis(2-hydroxy-4-butoxyphenyl)-6-(2,4-dibutoxyphenyl)-1,3-5-triazine is preferred.

[0060] Commercially available triazine compounds include, for example, "Tinuvin 400," "Tinuvin 405," "Tinuvin 460," "Tinuvin 477," and "Tinuvin 479," manufactured by BASF.

[0061] Examples of the triazole compounds include C7-C9-alkyl-3-[3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxyphenyl]propionether, 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-(2-hydroxy-5-tert-octylphenyl)benzotriazole, 2-(2-hydroxy-3,5-dicumylphenyl)phenylbenzotriazole, 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole, 2,2'-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl)phenol], 2-(2-hydroxy-3,5-di-tert-butylphenyl)benzotriazole, Examples of suitable benzotriazoles include triazole, 2-(2-hydroxy-3,5-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-3,5-di-tert-amylphenyl)benzotriazole, 2-(2-hydroxy-5-tert-octylphenyl)benzotriazole, 2-(2-hydroxy-5-tert-butylphenyl)benzotriazole, 2-(2-hydroxy-4-octoxyphenyl)benzotriazole, 2,2'-methylenebis(4-cumyl-6-benzotriazolephenyl), 2,2'-p-phenylenebis(1,3-benzoxazin-4-one), and 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimidomethyl)-5-methylphenyl]benzotriazole. These may be used alone or in combination of two or more. Of these, C7-C9-alkyl-3-[3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxyphenyl]propionether is preferred.

[0062] Commercially available triazole compounds include, for example, "Tinuvin PS," "Tinuvin 99-2," "Tinuvin 326," "Tinuvin 384-2," "Tinuvin 900," "Tinuvin 928," "Tinuvin 970," and "Tinuvin 1130," all manufactured by BASF.

[0063] Examples of the cyanoacrylate compounds include 2-ethylhexyl-2-cyano-3,3-diphenylacrylate, ethyl-2-cyano-3,3-diphenylacrylate, octyl-2-cyano-3,3-diphenylacrylate, etc. These may be used alone or in combination of two or more.

[0064] Commercially available cyanoacrylate compounds include, for example, "Uvinul 3035," "Uvinul 3039," and "Uvinul 3030," manufactured by BASF.

[0065] Among the above ultraviolet absorbers [II], triazine compounds and triazole compounds are preferred because they have superior adhesive strength, less yellowing, and superior ultraviolet absorbing ability.

[0066] The number average molecular weight of the ultraviolet absorber [II] is preferably 180 to 1500, more preferably 250 to 1000, and particularly preferably 300 to 800. If the number average molecular weight of the ultraviolet absorber [II] is too small, the yellowing resistance tends to decrease, and if the number average molecular weight is too large, the adhesive strength tends to decrease.

[0067] The ultraviolet absorber [II] preferably has a maximum absorption wavelength of 300 to 395 nm, more preferably 320 to 390 nm, particularly preferably 330 to 380 nm, and particularly preferably 340 to 370 nm. If the maximum absorption wavelength of the ultraviolet absorber [II] is too short, the ultraviolet absorption performance in the long wavelength region tends to decrease, while if the maximum absorption wavelength is too long, the yellowing resistance tends to decrease.

[0068] The content of the ultraviolet absorber [II] is preferably 0.01 to 20 parts by weight, particularly preferably 0.1 to 10 parts by weight, and further preferably 0.2 to 5 parts by weight, relative to 100 parts by weight of the polyester resin (I). If the content of the ultraviolet absorber [II] is too high, the adhesive strength tends to decrease, and if it is too low, the ultraviolet absorption performance tends to decrease.

[0069] <Hydrolysis inhibitor [III]> The pressure-sensitive adhesive composition of the present invention preferably further contains a hydrolysis inhibitor [III]. The hydrolysis inhibitor [III] is contained to ensure long-term durability.

[0070] The hydrolysis inhibitor [III] may be a conventionally known compound, such as a compound that reacts with and bonds to the carboxylic acid terminal group of the polyester resin [I]. Specific examples include compounds containing functional groups such as a carbodiimide group, an epoxy group, or an oxazoline group. The hydrolysis inhibitor [III] may be used alone or in combination of two or more. Among these, a carbodiimide group-containing compound is preferred because of its high effect of eliminating the catalytic activity of protons derived from the carboxylic acid terminal group.

[0071] As the carbodiimide group-containing compound, a known carbodiimide compound having one or more carbodiimide groups (-N=C=N-) in the molecule may usually be used, but in order to improve durability under high temperature and high humidity, a compound having two or more carbodiimide groups in the molecule, i.e., a polyvalent carbodiimide compound, is preferred, and in particular a compound having three or more, further five or more, and especially seven or more carbodiimide groups in the molecule is preferred. Note that the number of carbodiimide groups contained in the molecule of the polyvalent carbodiimide compound is usually 50 or less, and if there are too many carbodiimide groups, the molecular structure becomes too large, which tends to be undesirable.

[0072] As the carbodiimide group-containing compound, it is also preferable to use a high molecular weight polycarbodiimide produced by subjecting a diisocyanate to a decarboxylation condensation reaction in the presence of a carbodiimidization catalyst.

[0073] Such high molecular weight polycarbodiimides may be synthesized or commercially available products may be used. When synthesizing high molecular weight polycarbodiimides, for example, those obtained by subjecting the following diisocyanates to a decarboxylation condensation reaction may be used.

[0074] 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'-diphenylether diisocyanate, 3,3'-dimethyl-4,4'-diphenylether diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1-methoxyphenyl-2,4-diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and tetramethylxylylene diisocyanate. These can be used alone or in combination of two or more.

[0075] Furthermore, in terms of storage stability, it is preferable that the terminal isocyanate groups of the high-molecular-weight polycarbodiimide be blocked with a blocking agent. Examples of the blocking agent include compounds having active hydrogen that reacts with the isocyanate group, or compounds having an isocyanate group. Examples include monoalcohols, monocarboxylic acids, monoamines, and monoisocyanates each having one substituent selected from a carboxy group, an amino group, and an isocyanate group.

[0076] Examples of commercially available carbodiimide group-containing compounds include the Carbodilite (registered trademark) series manufactured by Nisshinbo Chemical Inc. Among these, Carbodilite (registered trademark) "V-01," "V-02B," "V-03," "V-04K," "V-04PF," "V-05," "V-07," "V-09," and "V-09GB" are preferred because of their excellent compatibility with organic solvents.

[0077] The carbodiimide equivalent of the carbodiimide group-containing compound is preferably 50 to 10,000, particularly 100 to 1,000, and more preferably 150 to 500. The carbodiimide equivalent indicates the chemical formula weight per carbodiimide group.

[0078] The epoxy group-containing compound used as the hydrolysis inhibitor [III] includes, for example, a glycidyl ester compound, a glycidyl ether compound, etc. These can be used alone or in combination of two or more kinds.

[0079] Specific examples of the glycidyl ester compound include 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 glycidyl ester, lauric acid glycidyl ester, palmitic acid glycidyl ester, behenic acid glycidyl ester, versatic acid glycidyl ester, oleic acid glycidyl ester, linoleic acid glycidyl ester, linolenic acid glycidyl ester, behenolic acid glycidyl ester, stearolic acid glycidyl ester, terephthalic acid diglycidyl ester, and isophthalic acid. Examples of the diglycidyl ester include diglycidyl ester, diglycidyl phthalate, diglycidyl naphthalenedicarboxylic acid, diglycidyl ester of methyl terephthalate, diglycidyl hexahydrophthalate, diglycidyl tetrahydrophthalate, diglycidyl ester of cyclohexanedicarboxylic acid, diglycidyl ester of adipic acid, diglycidyl ester of succinic acid, diglycidyl sebacic acid, diglycidyl ester of dodecanedioic acid, diglycidyl ester of octadecanedicarboxylic acid, triglycidyl trimellitate, and tetraglycidyl ester of pyromellitic acid. These may be used alone or in combination of two or more.

[0080] Specific examples of the glycidyl ether compound include phenyl glycidyl ether, o-phenyl glycidyl 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-[p-(β,γ-epoxypropoxy)phenyl]propane, and bisglycidyl polyethers obtained by reacting bisphenols such as 2,2-bis-(4-hydroxyphenyl)propane and 2,2-bis-(4-hydroxyphenyl)methane with epichlorohydrin, and the like. These can be used alone or in combination of two or more.

[0081] The oxazoline group-containing compound is preferably a bisoxazoline compound, etc. Specific examples include 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'-ethylene Examples of suitable terpolymers include 2,2'-tetramethylenebis(4,4-dimethyl-2-oxazoline), 2,2'-9,9'-diphenoxyethanebis(2-oxazoline), 2,2'-cyclohexylenebis(2-oxazoline), and 2,2'-diphenylenebis(2-oxazoline). Of these, 2,2'-bis(2-oxazoline) is most preferred in terms of reactivity with the polyester resin (A). These may be used alone or in combination of two or more.

[0082] The hydrolysis inhibitor [III] preferably has low volatility, and 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. Furthermore, from the viewpoint of hydrolysis resistance, it is preferable to use a hydrolysis inhibitor [III] having a high weight-average molecular weight. The weight-average molecular weight of the hydrolysis inhibitor [III] 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 50,000. If the molecular weight of the hydrolysis inhibitor [III] is too small, the hydrolysis resistance tends to decrease, whereas if the molecular weight is too large, the compatibility with the polyester resin [I] tends to decrease.

[0083] The content of the hydrolysis inhibitor [III] is preferably 0.01 to 10 parts by weight, particularly preferably 0.1 to 5 parts by weight, further preferably 0.3 to 3 parts by weight, and particularly preferably 0.5 to 2 parts by weight, relative to 100 parts by weight of the polyester resin [I]. If the content is too high, turbidity tends to occur due to poor compatibility with the polyester resin [I], while if the content is too low, sufficient durability tends to be difficult to obtain.

[0084] The content of the hydrolysis inhibitor [III] is preferably optimized depending on the acid value of the polyester resin [I], and the molar ratio [(b) / (a)] of the total number of moles (b) of functional groups of the hydrolysis inhibitor [III] in the polyester pressure-sensitive adhesive composition to the total number of moles (a) of acidic functional groups of the polyester resin in the polyester pressure-sensitive adhesive composition is preferably 0.5≦(b) / (a), particularly preferably 1≦(b) / (a)≦1000, and even more preferably 1.5≦(b) / (a)≦100. If the molar ratio of (b) to (a) is too low, the moisture and heat resistance tends to decrease. On the other hand, if the molar ratio of (b) to (a) is too high, the compatibility with the polyester resin [I] tends to decrease, and the adhesive strength, cohesive strength, and durability tend to decrease.

[0085] <Crosslinking agent [IV]> Examples of the crosslinking agent [IV] include compounds having a functional group that reacts with at least one of the hydroxyl group and the carboxyl group contained in the polyester resin [I], such as polyisocyanate compounds and polyepoxy compounds. Among these, it is particularly preferable to use polyisocyanate compounds, as they can achieve a good balance between initial adhesive strength, mechanical strength, and heat resistance.

[0086] Examples of such polyisocyanate compounds include polyisocyanates such as 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. Other examples include adducts of the above polyisocyanates with polyol compounds such as trimethylolpropane, and biuret and isocyanurate forms of these polyisocyanate compounds. The above polyisocyanate compounds may also be used in which the isocyanate moiety is blocked with phenol, lactam, or the like. These crosslinking agents [IV] may be used alone or in combination.

[0087] The content of the crosslinking agent [IV] can be appropriately selected depending on the molecular weight of the polyester resin [I] and the intended use. In general, the crosslinking agent [IV] is preferably contained in a proportion such that the reactive group contained in the crosslinking agent [IV] is 0.2 to 10 equivalents per equivalent of at least one of the hydroxyl group and the carboxy group contained in the polyester resin [I], particularly preferably 0.5 to 5 equivalents, and even more preferably 0.5 to 3 equivalents. If the equivalent number of the reactive group contained in such a crosslinking agent [IV] is too small, the cohesive strength tends to decrease, whereas if it is too large, the flexibility tends to decrease.

[0088] In addition, in the reaction between the polyester resin [I] and the crosslinking agent [IV], organic solvents that do not have functional groups that react with the components [I] and [IV], such as esters such as ethyl acetate and butyl acetate, ketones such as methyl ethyl ketone and methyl isobutyl ketone, and aromatics such as toluene and xylene, can be used. These can be used alone or in combination of two or more.

[0089] <Urethanization catalyst [V]> The pressure-sensitive adhesive composition of the present invention preferably further contains a urethanization catalyst [V]. As the urethanization catalyst [V], for example, an organometallic compound, a tertiary amine compound, etc. These can be used alone or in combination of two or more kinds.

[0090] Examples of the organometallic compounds include zirconium compounds, iron compounds, tin compounds, titanium compounds, lead compounds, cobalt compounds, and zinc compounds. Examples of zirconium compounds include zirconium naphthenate and zirconium acetylacetonate. Examples of iron compounds include iron acetylacetonate and iron 2-ethylhexanoate. Examples of tin compounds include dibutyltin dichloride, dibutyltin oxide, and dibutyltin dilaurate. Examples of titanium compounds include dibutyltitanium dichloride, tetrabutyltitanate, and butoxytitanium trichloride. 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 compounds include zinc naphthenate and zinc 2-ethylhexanoate.

[0091] Examples of the tertiary amine compound include triethylamine, triethylenediamine, and 1,8-diazabicyclo-(5,4,0)-undecene-7.

[0092] Among these urethane catalysts [V], organometallic compounds are preferred in terms of reaction rate and pot life of the adhesive layer, zirconium compounds are particularly preferred, and zirconium acetylacetonate is particularly preferred.

[0093] [Catalytic inhibitor] In the pressure-sensitive adhesive composition of the present invention, it is preferable to incorporate a catalytic inhibitor into the urethanation catalyst [V] in order to extend the pot life and improve the coatability. Examples of catalytic 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 keto-enol tautomeric compounds that protect the urethanization catalyst [V], thereby reducing the catalytic activity of the urethanization catalyst [V] in a solution state, suppressing excessive viscosity increase and gelation of the PSA composition after blending, and extending the pot life of the PSA composition. Among these, acetylacetone is preferably used as the catalyst inhibitor from the viewpoint of the balance between pot life and curing speed. These catalyst inhibitors can be used alone or in combination of two or more.

[0094] The blending ratio (weight ratio) of the catalytic inhibitor to the urethanization catalyst [V] is preferably in the range of catalytic inhibitor:urethanization catalyst [V] = 0.001:1 to 15:1, more preferably 0.005:1 to 13:1, and particularly preferably 0.01:1 to 10:1. If the content of the catalytic inhibitor relative to the content of the urethanization catalyst [V] is too low, the pot life tends to be short and the coatability tends to be reduced, whereas if it is too high, the curing rate tends to be reduced.

[0095] <Silane coupling agents [VI]> The pressure-sensitive adhesive composition of the present invention preferably further contains a silane coupling agent [VI]. Examples of the silane coupling agent [VI] include amino group-containing silane coupling agents, epoxy group-containing silane coupling agents, vinyl group-containing silane coupling agents, (meth)acryloyl group-containing silane coupling agents, mercapto group-containing silane coupling agents, isocyanate group-containing silane coupling agents, etc. These may be used alone or in combination of two or more kinds.

[0096] Examples of the amino group-containing silane coupling agent include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, and 3-phenylaminopropyltrimethoxysilane.

[0097] Examples of the epoxy group-containing silane coupling agent include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

[0098] Examples of the vinyl group-containing silane coupling agent include vinyltriacetoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane.

[0099] Examples of the (meth)acryloyl group-containing silane coupling agent include 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, and 3-(meth)acryloxypropyltriethoxysilane.

[0100] Examples of the mercapto group-containing silane coupling agent include 3-mercaptopropyltrimethoxysilane, 3-mercaptomethyldimethoxysilane, and 3-mercaptotriethoxysilane.

[0101] Examples of the isocyanate group-containing silane coupling agent include isocyanurate group-containing silane coupling agents such as tris-(trimethoxysilylpropyl)isocyanurate, and 3-isocyanatepropyltriethoxysilane.

[0102] Among these silane coupling agents, epoxy group-containing silane coupling agents are preferred, with 3-glycidoxypropyltrimethoxysilane being particularly preferred.

[0103] The content of the silane coupling agent [VI] is usually 0.01 to 10 parts by weight, preferably 0.02 to 5 parts by weight, particularly preferably 0.03 to 3 parts by weight, and further preferably 0.1 to 1 part by weight, relative to 100 parts by weight of the polyester resin [I]. If the content of the silane coupling agent [VI] is too high, the adhesive strength tends to decrease, and if it is too low, the adhesion to the substrate tends to decrease.

[0104] In addition to the above-mentioned polyester resin [I], ultraviolet absorber [II], hydrolysis inhibitor [III], crosslinking agent [IV], etc., the pressure-sensitive adhesive composition of the present invention may contain additives such as antioxidants such as hindered phenols, softeners, ultraviolet absorbers other than those mentioned above, stabilizers, antistatic agents, tackifiers, and other additives, such as inorganic or organic fillers, powders such as metal powders, pigments, and particulate additives, within the range that does not impair the effects of the present invention. These may be used alone or in combination of two or more.

[0105] In addition to the additives, the pressure-sensitive adhesive composition of the present invention may also contain small amounts of impurities contained in the raw materials for producing the components of the pressure-sensitive adhesive composition.

[0106] Such a pressure-sensitive adhesive composition can be obtained, for example, by preparing the polyester resin [I], the ultraviolet absorber [II], and, if necessary, optional components, etc., and mixing and dispersing them during the production of the polyester resin [I], or by mixing them with a solution of the polyester resin [I] dissolved in an organic solvent and dispersing them using a mixing roller.

[0107] The pressure-sensitive adhesive according to the present invention is made of the pressure-sensitive adhesive composition, that is, is obtained by crosslinking (curing) the pressure-sensitive adhesive composition.

[0108] The pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive. The pressure-sensitive adhesive sheet may be a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer on one or both sides of a supporting substrate, or may be a substrate-less double-sided pressure-sensitive adhesive sheet that does not have a substrate. 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 the present invention, the term "sheet" also includes "film" and "tape."

[0109] <Adhesive sheet> The pressure-sensitive adhesive sheet can be produced, for example, as follows. Such a pressure-sensitive adhesive sheet can be produced according to a known general method for producing a pressure-sensitive adhesive sheet. For example, the pressure-sensitive adhesive composition is applied to one side of a substrate, followed by drying to form a pressure-sensitive adhesive layer, and a release sheet is attached to the surface (the side opposite to the side that contacts the substrate) of the applied pressure-sensitive adhesive layer, followed by curing as necessary, to obtain the pressure-sensitive adhesive sheet of the present invention, which has a substrate and a pressure-sensitive adhesive layer, and in which the pressure-sensitive adhesive layer is provided on at least one side of the substrate.

[0110] Alternatively, the pressure-sensitive adhesive sheet of the present invention can be obtained by coating the pressure-sensitive adhesive composition on a release sheet, drying the composition to form a pressure-sensitive adhesive layer, laminating a substrate to the surface of the pressure-sensitive adhesive layer (the surface opposite to the surface that contacts the release sheet), and curing the layer as necessary.

[0111] Alternatively, a substrateless double-sided PSA sheet of the substrateless type can be produced by forming a PSA layer on a release sheet and laminating the release sheet and another release sheet to the surface of the PSA layer (the surface opposite to the surface in contact with the release sheet).

[0112] 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 is attached to an adherend.

[0113] Examples of the substrate include polyester resins such as polyethylene naphthalate, polyethylene terephthalate, polybutylene terephthalate, and polyethylene terephthalate / isophthalate copolymer; polyolefin resins such as polyethylene, polypropylene, and polymethylpentene; polyethylene fluoride resins such as polyvinyl fluoride, polyvinylidene fluoride, and polyethylene fluoride; 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; polystyrene; polycarbonate; polyarylate; polyimide; and synthetic resin sheets made of cycloolefin polymers, etc. Metal foils such as aluminum, copper, and iron; Paper such as fine paper and glassine paper; Examples include woven fabrics and nonwoven fabrics made of glass fibers, natural fibers, synthetic fibers, etc. These substrates can be used as a single layer or as a multi-layer structure in which two or more types are laminated.

[0114] Among these, substrates made of polyethylene terephthalate and polyimide are particularly preferred, with polyethylene terephthalate being particularly preferred because of its excellent adhesion to the adhesive. Furthermore, polyethylene terephthalate having a metal thin film layer is preferred because it has excellent adhesion between the substrate and the adhesive, can maintain the substrate stably without corroding the metal thin film layer, and can significantly demonstrate the effects of the adhesive used in the present invention.

[0115] In the present invention, it is also preferable to use an optical laminate in which an ITO electrode film is formed as a thin film on a polyethylene terephthalate (PET) substrate and the PET side of the film has an adhesive layer, the PET substrate and a polycarbonate (PC) film are laminated via the adhesive layer, and an acrylic film is further laminated (layer structure: ITO electrode film / PET substrate / adhesive layer / PC film / acrylic film).

[0116] As the release sheet, for example, a release-treated synthetic resin sheet, paper, cloth, nonwoven fabric, etc., exemplified above as the substrate, can be used. Among them, it is preferable to use a silicone-based release sheet.

[0117] The thickness of the substrate is, for example, preferably 1 to 1000 μm, particularly preferably 2 to 500 μm, and further preferably 3 to 300 μm.

[0118] The pressure-sensitive adhesive composition may be applied using, for example, a gravure roll coater, reverse roll coater, kiss roll coater, dip roll coater, bar coater, knife coater, spray coater, comma coater, or the like.

[0119] As for the drying conditions after coating the pressure-sensitive adhesive composition, the drying temperature is preferably 60 to 140° C., particularly preferably 80 to 120° C. The drying time is preferably 0.5 to 30 minutes, particularly preferably 1 to 5 minutes.

[0120] The conditions for the aging treatment are generally room temperature (23°C) to 70°C, and the time is generally 1 to 30 days. Specifically, the treatment may 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 pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet and the substrate-less double-sided pressure-sensitive adhesive sheet is preferably 2 to 500 μm, particularly preferably 5 to 300 μm, and even more preferably 10 to 200 μm. If the thickness of the pressure-sensitive adhesive layer is too thin, the adhesive strength tends to decrease, while if it is too thick, it becomes difficult to apply uniformly and problems such as air bubbles entering the coating film tend to occur. When considering impact absorption properties, a thickness of 50 μm or more is preferable.

[0122] The thickness of the adhesive layer is determined by subtracting the measured thickness of the components other than the adhesive layer from the measured thickness of the entire adhesive sheet using a Digimatic Indicator (ID-C112B, manufactured by Mitutoyo Corporation).

[0123] The gel fraction of the pressure-sensitive adhesive layer is preferably 10% by weight or more from the viewpoint of durability and adhesive strength, particularly preferably 15 to 80% by weight, and even more preferably 20 to 70% by weight. If the gel fraction is too low, the cohesive strength tends to decrease, resulting in a decrease in durability. However, if the gel fraction is too high, there is a concern that the adhesive strength will decrease due to an increase in cohesive strength.

[0124] The gel fraction is an index of the degree of crosslinking and is calculated, for example, by the following method. That is, a pressure-sensitive adhesive sheet (without a separator) consisting of a substrate polymer sheet (e.g., a PET film) on which a pressure-sensitive adhesive layer is formed is wrapped in a 200-mesh SUS wire netting and immersed in toluene at 23°C for 24 hours, and the gel fraction is calculated as the weight percentage of the insoluble pressure-sensitive adhesive component remaining in the wire netting after immersion relative to the weight of the pressure-sensitive adhesive component before immersion, excluding the weight of the substrate.

[0125] Furthermore, such a pressure-sensitive adhesive sheet may, if necessary, be provided with a release sheet on the outer side of the pressure-sensitive adhesive layer to protect the pressure-sensitive adhesive layer. Also, in a pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive layer is formed on one side of a substrate, it is possible to protect the pressure-sensitive adhesive layer by applying a release treatment to the side of the substrate opposite the pressure-sensitive adhesive layer, thereby utilizing the release-treated surface.

[0126] The pressure-sensitive adhesive of the present invention can be used for bonding various members, and is preferably used as a pressure-sensitive adhesive for optical members used for bonding optical members. The pressure-sensitive adhesive layer of the pressure-sensitive adhesive composition can be laminated on an optical member to obtain the above-mentioned optical member with the pressure-sensitive adhesive layer.

[0127] Examples of such optical components include transparent electrode films such as ITO electrode films and inorganic or organic conductive films such as polythiophene, polarizing plates, retardation plates, elliptically polarizing plates, optical compensation films, brightness enhancement films, electromagnetic wave shielding films, near-infrared absorbing films, and AR (anti-reflection) films. Among these, the optical component is particularly effective when it is a transparent electrode film, and is preferred because it can provide high adhesive strength, and an ITO electrode film is particularly preferred. Note that ITO electrode films are often formed as a thin film on a substrate such as glass or PET, but in the present invention, as already mentioned, it is particularly preferred to use a film in which the ITO electrode film is formed as a thin film on a PET substrate. The film is also suitable for use as a light extraction film provided on the light emitting surface of a surface emitter of an organic EL element, or as a light diffusion sheet for a liquid crystal display.

[0128] The optical member with the pressure-sensitive adhesive layer preferably further has a release film on the surface of the pressure-sensitive adhesive layer opposite to the optical member surface, and when used in practice, the release film is peeled off and the pressure-sensitive adhesive layer is attached to an adherend. As such a release film, a silicone-based release film is preferably used. [Example]

[0129] 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 as long as it does not depart from the gist of the invention. In the examples, "parts" and "%" are by weight unless otherwise specified. The glass transition temperature of the polyester resin [I] in the following examples was measured according to the method described above.

[0130] Prior to the examples, the following components were prepared.

[0131] [Production of polyester resin [I]] The mol % of each component of the polycarboxylic acid (A) described in the following production examples indicates the molar ratio when the total amount of the polycarboxylic acid (A) is taken as 100 mol %. Furthermore, the mol % of each component of polyol (B) described in the following production examples indicates the molar ratio when the total amount of polyol (B) is taken as 100 mol %.

[0132] [Polyester resin [I-1]] A reactor equipped with a heater, a thermometer, a stirrer, a rectifying column, a nitrogen inlet tube, and a vacuum device was charged with 76.6 parts of isophthalic acid, 186.5 parts of sebacic acid, and 173.6 parts of azelaic acid as polycarboxylic acids (A), 14.3 parts of ethylene glycol and 349 parts of cyclohexanedimethanol as polyols (B), and 0.04 parts of germanium dioxide as a catalyst, and the internal temperature was gradually raised to 250°C, and an esterification reaction was carried out over 4 hours. Thereafter, the internal temperature was raised to 270°C, the pressure was reduced to 1.33 hPa, and a polycondensation reaction was carried out over 3 hours to produce a polyester resin [I-1]. The resulting polyester resin [I-1] had a glass transition temperature of -25°C and a weight-average molecular weight of 60000. The final component ratio was 20 mol% / 40 mol% / 40 mol% of isophthalic acid / sebacic acid / azelaic acid as the polycarboxylic acids (A) and 8 mol% / 92 mol% of ethylene glycol / cyclohexanedimethanol as the polyol (B).

[0133] [Ultraviolet absorber [II]] [II-1]: Triazine-based UV absorber (BASF, "Tinuvin 460," number-average molecular weight 630, maximum absorption wavelength 349 nm) [II-2]: Triazole-based UV absorber (BASF, "Tinuvin 384-2," number-average molecular weight 451.6, maximum absorption wavelength 345 nm) [II'-1]: Benzophenone-based ultraviolet absorber (BASF, "Uvinul 3050," number-average molecular weight 246, maximum absorption wavelength 346 nm)

[0134] [Hydrolysis inhibitor [III]] [III-1]: Aromatic polycarbodiimide compound in which the isocyanate terminal is substituted with a substituent derived from polyethylene glycol monomethyl ether (Nisshinbo Chemical Co., Ltd., "Carbodilite V-04PF")

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

[0136] [Urethanization catalyst [V]] [V-1]: Zirconium compound diluted with acetylacetone to a solids concentration of 1% (Matsumoto Fine Chemical Co., Ltd., "Orgatix ZC-150")

[0137] [Silane coupling agents [VI]] [VI-1]: 3-glycidoxypropyltrimethoxysilane (Shin-Etsu Silicones Co., Ltd., "KBM-403")

[0138] Example 1 The polyester resin [I-1] obtained above was diluted with toluene to a solids concentration of 50%, and this polyester resin [I-1] solution (100 parts as solids) was blended with 3 parts of ultraviolet absorber [II-1], 1.5 parts of hydrolysis inhibitor [III-1], 2.25 parts (solids) of crosslinker [IV-1], 0.02 parts (solids) of urethane catalyst [V-1], and 0.1 parts of silane coupling agent [VI-1], and stirred and mixed to obtain a pressure-sensitive adhesive composition.

[0139] Example 2 A pressure-sensitive adhesive composition was obtained in the same manner as in Example 1, except that 3 parts of the ultraviolet absorber [II-1] was changed to 4 parts of [II-2].

[0140] (Comparative Example 1) A pressure-sensitive adhesive composition was obtained in the same manner as in Example 1, except that 3 parts of the ultraviolet absorber [II-1] was changed to 1.5 parts of [II'-1].

[0141] (Comparative Example 2) An adhesive composition was obtained by compounding 4 parts of ultraviolet absorber [II-2], 0.4 parts (solids) of crosslinker [IV-1], and 0.1 parts of silane coupling agent [VI-1] into the acrylic resin [I'] solution (100 parts as solids) obtained as described below, and stirring and mixing the mixture. [Production of acrylic resin [I']] A four-necked round-bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet, and a thermometer was charged with 38.8 parts of butyl acrylate, 60 parts of methyl acrylate, 1.0 part of hydroxyethyl methacrylate, 0.2 parts of 2-(dimethylamino)ethyl acrylate, 60 parts of ethyl acetate, and 8 parts of methyl ethyl ketone. After heating to reflux, 0.5 parts of azobisisobutyronitrile (AIBN) was added as a polymerization initiator, and the mixture was allowed to react for 7 hours at the ethyl acetate reflux temperature. The mixture was then diluted with 98 parts of ethyl acetate and 20 parts of methyl ethyl ketone to produce an acrylic resin [I'] solution. The resulting acrylic resin [I'] had a glass transition temperature of -21°C and a weight average molecular weight of 530,000.

[0142] (Comparative Example 3) A pressure-sensitive adhesive composition was obtained in the same manner as in Comparative Example 2, except that 4 parts of the ultraviolet absorber [II-2] was changed to 1.5 parts of [II'-1].

[0143] The resulting pressure-sensitive adhesive compositions were evaluated as follows, and the results are shown in Table 1 below.

[0144] <Production of substrate-less double-sided adhesive sheets> The adhesive compositions obtained in the examples and comparative examples were applied to a 38 μm thick PET release film (Mitsui Chemicals Tohcello, SP-PET-03-BU) (Fα) using an applicator and dried at 100°C for 4 minutes to obtain adhesive sheets with a release film having an adhesive layer thickness of 50 μm. Next, the surface of the adhesive layer of the obtained adhesive sheet with release film was covered with a 38 μm thick PET release film (Mitsui Chemicals Tocello, SP-PET-01-BU) (Fβ) which had a different peel strength than the above release film (Fα), and the film was cured at 40°C for 7 days to obtain a substrateless double-sided adhesive sheet.

[0145] <Adhesive sheet evaluation> [Adhesive strength] The release film (Fβ) on one side of the substrateless double-sided PSA sheet obtained above was peeled off, and the PSA layer was transferred to a PET film (100 μm) to prepare a PSA sheet for evaluation. The obtained PSA sheet for evaluation was cut to a width of 10 mm, and the separator on the other side was peeled off to attach the exposed PSA layer to an alkali-free glass plate (Corning, Eagle XG), which was then autoclaved (50°C, 0.5 MPa, 20 minutes) to prepare a test piece having a PET film / adhesive layer / alkali-free glass plate configuration. The 180-degree peel strength of the test specimens was measured at 23°C and 50% RH using a thermostatic tensile tester (Shimadzu Corporation, Autograph AG-X 50N) at a peel rate of 60 mm / min, and evaluated according to the following criteria. The results are also shown in Table 1. (Evaluation criteria) ○··· Greater than 5N / 10mm △··· More than 3N / 10mm and 5N / 10mm or less ×...3N / 10mm or less

[0146] [Adhesion to substrate] The release film (Fβ) on one side of the substrateless double-sided PSA sheet obtained above was peeled off, and the PSA layer was transferred to a PET film (100 μm) to prepare a PSA sheet for evaluation. The obtained PSA sheet for evaluation was cut to a width of 10 mm, and the separator on the other side was peeled off to attach the exposed PSA layer to an alkali-free glass plate (Corning, Eagle XG), which was then autoclaved (50°C, 0.5 MPa, 20 minutes) to prepare a test piece having a PET film / adhesive layer / alkali-free glass plate configuration. The 180-degree peel strength of the above test specimens was measured at 23°C and 50% RH using a thermostatic chamber equipped tensile tester (Shimadzu Corporation, Autograph AG-X 50N) at a peel rate of 60 mm / min. The peel mode was evaluated according to the following criteria. The results are also shown in Table 1. (Evaluation criteria) ○...Adherent interface peeling ×...Interface peeling or cohesive failure of substrate

[0147] [Yellowing resistance] The release film (Fβ) on one side of the substrateless double-sided pressure-sensitive adhesive sheet obtained above was peeled off, the pressure-sensitive adhesive layer was transferred to an alkali-free glass plate (Corning Eagle XG), and the release film (Fα) on the other side was peeled off to prepare a test piece having a pressure-sensitive adhesive layer / alkali-free glass configuration. The obtained test piece was measured using a color difference meter (Nippon Denshoku Industries Co., Ltd., SE6000) to obtain a color difference of b * The values ​​were measured and evaluated according to the following criteria. The results are shown in Table 1. (Evaluation criteria) ○ 2 or less × 2 or more

[0148] [UV absorption capacity] The release film (Fβ) on one side of the substrateless double-sided PSA sheet obtained above was peeled off, the PSA layer was transferred to an alkali-free glass plate (Corning Eagle XG), and the release film (Fα) on the other side was peeled off to prepare a test piece having a PSA layer / alkali-free glass configuration. The UV transmittance (%) of the obtained test piece at 380 nm was measured using a UV-Visible-Near-Infrared Spectrophotometer (JASCO V-7200) and evaluated according to the following criteria. The results are also shown in Table 1. (Evaluation criteria) ○ 5% or less △ More than 5% and up to 10% × More than 10%

[0149] [Table 1]

[0150] The results in Table 1 above show that the pressure-sensitive adhesive compositions of Examples 1 and 2 have excellent adhesive strength and substrate adhesion, as well as little yellowing and excellent ultraviolet absorption ability. In contrast, the pressure-sensitive adhesive composition of Comparative Example 1 had good adhesive strength, substrate adhesion, and UV absorption ability, but yellowing was observed, and its performance as a pressure-sensitive adhesive for optical components was poor. Furthermore, Comparative Examples 2 and 3, which used acrylic resins, had poor substrate adhesion, but there was no particular difference in adhesive strength and UV absorption ability depending on the type of UV absorber. This also shows that the combination of a polyester resin with a UV absorber is very important for pressure-sensitive adhesive compositions containing polyester resins. [Industrial Applicability]

[0151] The pressure-sensitive adhesive composition of the present invention has excellent adhesive strength and adhesion to substrates, while exhibiting little yellowing and excellent ultraviolet absorption ability. Therefore, pressure-sensitive adhesives and pressure-sensitive adhesive sheets using the composition can be suitably used for bonding optical components in displays and optical components such as optical films and substrates that constitute such displays.

Claims

1. A polyester-based pressure-sensitive adhesive composition comprising a polyester-based resin [I] containing a structural unit derived from a polycarboxylic acid (A) and a structural unit derived from a polyol (B) (excluding polyester-based resins having a glass transition temperature in the range of −80 to 0° C. and having a hydroxyl group and / or a carboxyl group in a side chain), and an ultraviolet absorber [II], the polycarboxylic acids (A) contain asymmetric aromatic dicarboxylic acids (A-1) and aliphatic dicarboxylic acids (A-2) having 4 or more carbon atoms, and the content ratio (molar ratio) of the asymmetric aromatic dicarboxylic acids (A-1) to the aliphatic dicarboxylic acids (A-2) having 4 or more carbon atoms is (A-1) / (A-2)=1 / 99 to 60 / 40; the ultraviolet absorber [II] is at least one selected from a triazine-based compound and a triazole-based compound, The polyester-based pressure-sensitive adhesive composition is characterized in that it contains 0.01 to 10 parts by weight of a silane coupling agent [VI] per 100 parts by weight of a polyester-based resin [I].

2. 2. The polyester-based pressure-sensitive adhesive composition according to claim 1, wherein the polyester-based resin [I] has a glass transition temperature (Tg) of -70 to 20°C.

3. 3. The polyester-based pressure-sensitive adhesive composition according to claim 1, wherein the number-average molecular weight of the ultraviolet absorber [II] is 180 to 1,500.

4. 4. The polyester-based pressure-sensitive adhesive composition according to claim 1, wherein the ultraviolet absorber [II] has a maximum absorption wavelength in the range of 300 to 395 nm.

5. The polyester-based pressure-sensitive adhesive composition according to any one of claims 1 to 4, further comprising a hydrolysis inhibitor [III].

6. The polyester-based pressure-sensitive adhesive composition according to any one of claims 1 to 5, further comprising a crosslinking agent [IV].

7. A pressure-sensitive adhesive obtained by crosslinking the polyester-based pressure-sensitive adhesive composition according to any one of claims 1 to 6.

8. A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive according to claim 7.

9. 9. The adhesive sheet according to claim 8, comprising a substrate and an adhesive layer, the adhesive layer being provided on at least one surface of the substrate.

10. 9. The pressure-sensitive adhesive sheet according to claim 8, which is a substrate-less type pressure-sensitive adhesive sheet having no substrate.

11. The pressure-sensitive adhesive sheet according to any one of claims 8 to 10, which is used for bonding optical members.

12. 8. An optical member with a pressure-sensitive adhesive layer, comprising a pressure-sensitive adhesive layer and an optical member, wherein the pressure-sensitive adhesive layer contains the pressure-sensitive adhesive according to claim 7.

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