Polyester-based pressure-sensitive adhesive composition, polyester-based pressure-sensitive adhesive, pressure-sensitive adhesive sheet, decorative film, film for electronic member, and decorative molded object

Abstract

Provided is a polyester-based pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive excellent in terms of adhesive force, heat resistance, moist heat resistance, and optical properties. The polyester-based pressure-sensitive adhesive composition comprises a polyester-based resin (A) and a polyepoxy-based compound (B), wherein the polyester-based resin (A) comprises structural units derived from a polycarboxylic acid and structural units derived from a polyhydric alcohol, the structural units derived from a polycarboxylic acid including a specific amount of a structural unit derived from a cyclic structure and the structural units derived from a polyhydric alcohol including a structural unit derived from an aliphatic polyhydric alcohol. The polyester-based resin (A) has a specific acid value and a specific glass transition temperature.

Description

Polyester-based pressure-sensitive adhesive composition, polyester-based pressure-sensitive adhesive, pressure-sensitive adhesive sheet, decorative film, film for electronic components, and decorated molded body

[0001] The present invention relates to a polyester-based pressure-sensitive adhesive composition, a polyester-based pressure-sensitive adhesive, a pressure-sensitive adhesive sheet, a decorative film, a film for electronic components, and a decorated molded article, and more particularly to a polyester-based pressure-sensitive adhesive composition having excellent adhesive strength, heat resistance, moist heat resistance, and 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, a decorative film made of the pressure-sensitive adhesive sheet, and a decorated molded article formed by laminating the decorative film.

[0002] Conventionally, polyester resins have been used in a wide range of applications, such as films, PET bottles, fibers, toner, electrical components, adhesives, and pressure-sensitive adhesives, due to their excellent heat resistance, chemical resistance, durability, and mechanical strength. In addition, polyester resins have high polarity due to their polymer structure, and are therefore known to exhibit excellent adhesion to polar polymers such as polyester, polyvinyl chloride, polyimide, and epoxy resin, as well as to metal materials such as copper and aluminum.

[0003] Furthermore, decorative films are being applied or transferred to molded products such as automobile interior and exterior parts, home appliance parts, and building material parts as an alternative to conventional painting methods in order to improve design and reduce VOC (volatile organic compounds) emissions. Forming methods using decorative films include in-mold molding using injection molding, vacuum forming, and vacuum-pressure forming. Also known as decorative films to be applied to molded products is a decorative film having a pressure-sensitive adhesive layer.

[0004] Patent Document 1 proposes a thermoplastic polyester elastomer having excellent moldability, water resistance, and weather resistance, which is a copolymer polyester in which the acid component is mainly composed of an aromatic dicarboxylic acid and the glycol component contains 1 to 60 mol % of dimer diol based on the total glycol component, and which has a reduced viscosity of 0.5 to 3.0.

[0005] Furthermore, Patent Document 2 proposes a polyester-based pressure-sensitive adhesive composition that exhibits little change over time, such as an increase in adhesive strength, even when used in a high-temperature environment. The polyester-based pressure-sensitive adhesive composition is characterized by containing a polyester-based resin having a carboxy group derived from at least one of a trivalent or higher carboxylic acid and its acid anhydride, at at least one of the side chain and terminal of the molecule.

[0006] Furthermore, Patent Document 3 proposes an adhesive composition that contains 50 mol % or more of a naphthalenedicarboxylic acid component when the polyvalent carboxylic acid component is taken as 100 mol %, and contains at least one of a dimer diol component and tricyclodecane dimethanol as a polyhydric alcohol component, as a polyester that has excellent solvent solubility, heat resistance, low tack, and low dielectric constant and dielectric dissipation factor, and has excellent dielectric properties.

[0007] Patent Document 4 proposes an adhesive composition that has excellent long-term durability in a humid and hot environment and also has high adhesive properties, and that contains a polyester resin that satisfies the requirements of an ester bond concentration of 7 mmol / g or less, an acid value of 3 mgKOH / g or more, and a glass transition temperature of −5° C. or more.

[0008] Japanese Patent Laid-Open No. 6-128363 Japanese Patent Laid-Open No. 2019-119872 International Publication No. 2021 / 200713 Japanese Patent Laid-Open No. 2020-134344

[0009] However, in recent years, there has been a demand for decorative molding of molded articles with complex surface shapes, such as three-dimensional curves, and this has led to the need for heat molding at higher temperatures than before. This has led to issues with heat resistance, such as thermal decomposition of the adhesive used in the decorative film, and optical properties, such as reduced transparency of the adhesive layer. While increasing the glass transition temperature of the resin is usually considered to improve heat resistance, this can lead to problems such as the resin becoming harder and reducing adhesive strength and optical properties, making it difficult to achieve both of these properties at a high level.

[0010] For example, Patent Document 1 discloses a technology related to polyester elastomers, but because the polyester-based resin has high crystallinity, it has low tack at room temperature (23° C.), making it difficult to use it for pressure-sensitive adhesive applications. In addition, because the polyester-based resin does not have an acid value that serves as a reaction point with the polyepoxy-based compound, heat resistance has not been taken into consideration.

[0011] Furthermore, Patent Document 2 discloses a technology relating to a polyester-based pressure-sensitive adhesive for masking, which has excellent heat resistance, but the acid value of the polyester-based resin that forms the crosslinking point with the polyepoxy-based compound is too high, resulting in a high crosslinking density and extremely low adhesive strength, which remains a problem. Furthermore, no consideration is given to moist heat resistance, and there is room for improvement in long-term durability in moist and hot environments.

[0012] Patent Document 3 discloses a technology related to polyesters with excellent dielectric properties, and because the polycarboxylic acids contain a large amount of polycyclic polycarboxylic acids with high crystal orientation in order to reduce the dielectric constant, dielectric loss tangent, and water absorption, the glass transition temperature is high, which results in problems with tackiness and molding stability when made into a pressure-sensitive adhesive sheet. In addition, the polyhydric alcohols contain a large amount of polyhydric alcohols with long-chain alkyl groups with low polarity, which results in poor solubility in polar solvents, resulting in problems with the long-term stability of the resin solution and poor compatibility with polyepoxy compounds and the like, resulting in poor optical properties.

[0013] Patent Document 4 discloses a technique related to a polyester adhesive, and since the glass transition temperature of the polyester resin is high in order to make it tack-free, and the tackiness at room temperature (23°C) is low, it is difficult to use it for pressure-sensitive adhesive applications.

[0014] Therefore, in this context, the present invention provides a polyester-based pressure-sensitive adhesive composition having excellent adhesive strength, heat resistance, moist heat resistance, and optical properties, as well as a pressure-sensitive adhesive, a pressure-sensitive adhesive sheet, a decorative film, a film for electronic components, and a decorated molded body, which are crosslinked from such a pressure-sensitive adhesive composition.

[0015] However, in view of these circumstances, the present inventors have conducted extensive research and have found that by crosslinking a polyester resin having a specific acid value and glass transition temperature, and containing structural units derived from cyclic structure-containing polycarboxylic acids and structural units derived from aliphatic polyhydric alcohols, with a polyepoxy compound, it is possible to obtain a polyester pressure-sensitive adhesive composition that has a low glass transition temperature and excellent adhesive strength, while also exhibiting excellent heat resistance, moist heat resistance, and optical properties, which have previously been traded off against each other.

[0016] That is, the gist of the present invention is the following [1] to

[21] . [1] A polyester-based pressure-sensitive adhesive composition containing a polyester-based resin (A) and a polyepoxy-based compound (B), wherein the polyester-based resin (A) satisfies all of the following (1) to (6): (1) The polyester-based resin (A) has structural units derived from polycarboxylic acids (a) and structural units derived from polyhydric alcohols (b). (2) The content of structural units derived from cyclic structure-containing polycarboxylic acids (a1) relative to 100 mol % of the structural units derived from the polycarboxylic acids (a) is 30 mol % or more. (3) The structural units derived from the polyhydric alcohols (b) contain structural units derived from aliphatic polyhydric alcohols (b1). (4) The acid value of the polyester-based resin (A) is 1.5 to 30 mgKOH / g. (5) The glass transition temperature of the polyester-based resin (A) is -75 to -20°C. (6) The structural units derived from cyclic esters in the polyester resin (A) account for less than 140 mol% relative to 100 mol% of the structural units derived from polycarboxylic acids (a). [2] The polyester pressure-sensitive adhesive composition according to [1], wherein the structural units derived from the cyclic structure-containing polycarboxylic acids (a1) are structural units derived from monocyclic polycarboxylic acids (a1-1). [3] The polyester pressure-sensitive adhesive composition according to [1] or [2], wherein the structural units derived from the aliphatic polyhydric alcohols (b1) contain structural units derived from polyhydric alcohols having a hydrocarbon group in at least one side chain. [4] The polyester pressure-sensitive adhesive composition according to any one of [1] to [3], wherein the polyester resin (A) has structural units derived from dimer acids (a2) and / or structural units derived from dimer diols (b2). [5] The polyester-based pressure-sensitive adhesive composition according to any one of [1] to [4], wherein the content of structural units derived from aliphatic polyhydric alcohols (b1) relative to 100 mol % of structural units derived from the polyhydric alcohols (b) is 5 to 80 mol %. [6] The polyester-based pressure-sensitive adhesive composition according to any one of [1] to [5], wherein the structural units derived from the polyhydric alcohols (b) contain structural units derived from dimer diols (b2).[7] The polyester-based pressure-sensitive adhesive composition according to any one of [1] to [6], wherein the total content of the structural units derived from the dimer acid (a2) and the structural units derived from the dimer diol (b2) relative to the total mass of the polyester-based resin (A) is 20 to 90 mass%. [8] The polyester-based pressure-sensitive adhesive composition according to any one of [1] to [7], wherein the ester bond concentration of the polyester-based resin (A) is 1.5 to 8.0 mmol / g. [9] The polyester-based pressure-sensitive adhesive composition according to any one of [1] to [8], wherein the heat of crystalline fusion of the polyester-based resin (A) is 3 J / g or less.

[10] The polyester-based pressure-sensitive adhesive composition according to any one of [1] to [9], wherein the polyepoxy-based compound (B) contains a nitrogen-containing polyepoxy-based compound.

[11] The polyester-based pressure-sensitive adhesive composition according to any one of [1] to

[10] , wherein the equivalent of the epoxy group of the polyepoxy-based compound (B) relative to the carboxy group of the polyester-based resin (A) is 0.3 to 5 equivalents.

[12] The polyester-based pressure-sensitive adhesive composition according to any one of [1] to

[11] , wherein the content of the polyepoxy compound (B) is 0.1 to 15 parts by mass relative to 100 parts by mass of the polyester-based resin (A).

[13] A polyester-based pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition according to any one of [1] to

[12] .

[14] The polyester-based pressure-sensitive adhesive according to

[13] , wherein the gel fraction is 20 to 100%.

[15] A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive according to

[13] or

[14] .

[16] The pressure-sensitive adhesive sheet according to

[15] , wherein the haze is 3% or less.

[17] A pressure-sensitive adhesive sheet having a substrate and a pressure-sensitive adhesive layer containing the polyester-based pressure-sensitive adhesive according to

[13] or

[14] , wherein the pressure-sensitive adhesive layer is provided on at least one surface of the substrate.

[18] A decorative film comprising the pressure-sensitive adhesive sheet according to

[17] .

[19] A film for electronic components comprising the pressure-sensitive adhesive sheet according to

[17] .

[20] A decorated molded body obtained by laminating the decorative film according to

[18] on a molded body.

[21] A decorative film having a pressure-sensitive adhesive layer formed from a polyester-based pressure-sensitive adhesive composition containing a polyester-based resin (A) and a polyepoxy-based compound (B), wherein the polyester-based resin (A) satisfies all of the following (1) to (4):(1) The polyester-based resin (A) has structural units derived from polycarboxylic acids (a) and structural units derived from polyhydric alcohols (b). (2) The content of structural units derived from cyclic structure-containing polycarboxylic acids (a1) relative to 100 mol % of structural units derived from polycarboxylic acids (a) is 30 mol % or more. (3) The structural units derived from polyhydric alcohols (b) contain structural units derived from aliphatic polyhydric alcohols (b1). (4) The acid value of the polyester-based resin (A) is 1.5 to 30 mgKOH / g.

[0017] The polyester-based pressure-sensitive adhesive composition of the present invention can form a pressure-sensitive adhesive having excellent adhesive strength, heat resistance, moist heat resistance, and optical properties, and such a pressure-sensitive adhesive composition is particularly effective as a pressure-sensitive adhesive used in decorative films and films for electronic components.

[0018] Generally, it is known that in order to improve the heat resistance and moist heat resistance of a polyester pressure-sensitive adhesive composition, the glass transition temperature of the polyester resin is increased or functional groups are added to increase the number of crosslinking points.However, in the present invention, by crosslinking a polyester resin having a specific acid value and glass transition temperature, and containing a structural unit derived from an aliphatic polyhydric alcohol, which may intentionally reduce durability, in addition to a structural unit derived from a polycarboxylic acid containing a cyclic structure, with a polyepoxy compound, the composition has a low glass transition temperature, tackiness at room temperature (23°C), and excellent adhesive strength, while also having excellent heat resistance, moist heat resistance, and optical properties, which have traditionally been trade-offs.

[0019] The configuration of the present invention will be described in detail below, but these are examples of preferred embodiments. In the present invention, the term "class" added after the name of a compound is a concept that encompasses not only the compound but also derivatives of the compound. For example, the term "carboxylic acid class" includes not only carboxylic acid but also carboxylic acid derivatives such as carboxylic acid salts, carboxylic acid anhydrides, carboxylic acid halides, and carboxylic acid esters. Furthermore, "X and / or Y (X and Y are optional configurations)" means at least one of X and Y, and can mean three cases: X only, Y only, or X and Y.

[0020] A polyester-based pressure-sensitive adhesive composition according to one embodiment of the present invention (hereinafter sometimes referred to as "the pressure-sensitive adhesive composition") contains a polyester-based resin (A) and a polyepoxy-based compound (B), and the polyester-based resin (A) satisfies all of the following (1) to (6): (1) The polyester-based resin (A) has structural units derived from polycarboxylic acids (a) and structural units derived from polyhydric alcohols (b). (2) The content of structural units derived from cyclic structure-containing polycarboxylic acids (a1) relative to 100 mol % of structural units derived from polycarboxylic acids (a) is 30 mol % or more. (3) The structural units derived from polyhydric alcohols (b) contain structural units derived from aliphatic polyhydric alcohols (b1). (4) The acid value of the polyester-based resin (A) is 1.5 to 30 mgKOH / g. (5) The glass transition temperature of the polyester-based resin (A) is -75 to -20°C. (6) The structural units derived from cyclic esters in the polyester resin (A) account for less than 140 mol % relative to 100 mol % of the structural units derived from polycarboxylic acids (a). Hereinafter, each component contained in the pressure-sensitive adhesive composition will be described.

[0021] <Polyester-based resin (A)> The polyester-based resin (A) has a structural unit derived from a polycarboxylic acid (a) and a structural unit derived from a polyhydric alcohol (b) in the molecule, and is preferably obtained by ester bonding the polycarboxylic acid (a) and the polyhydric alcohol (b).

[0022] [Polycarboxylic Acids (a)] Examples of the polycarboxylic acids (a) include cyclic structure-containing polycarboxylic acids (a1) such as monocyclic polycarboxylic acids and polycyclic polycarboxylic acids; dimer acids (a2), trivalent or higher polycarboxylic acids having 0 or 1 acid anhydride group; and aliphatic polycarboxylic acids. In the present invention, from the viewpoint of moist heat resistance, the polyester resin (A) contains a structural unit derived from the cyclic structure-containing polycarboxylic acid (a1). Moreover, one or more types of polycarboxylic acids (a1) can be used.

[0023] The content of structural units derived from the cyclic structure-containing polycarboxylic acids (a1) relative to 100 mol% of structural units derived from the polycarboxylic acids (a) is 30 mol% or more, preferably 40 to 99 mol%, more preferably 50 to 95 mol%, particularly preferably 55 to 90 mol%, and especially preferably 60 to 85 mol% or more. The upper limit is usually 100 mol%. If the content of structural units derived from the cyclic structure-containing polycarboxylic acids (a1) is too low, the heat resistance and moist heat resistance will be insufficient. On the other hand, if the content is too high, the compatibility with the polyepoxy compound (B) will decrease, resulting in insufficient optical properties, and the glass transition temperature will increase, resulting in insufficient tackiness, adhesive strength, and molding stability.

[0024] The content (molar ratio) of the structural units derived from the cyclic structure-containing polycarboxylic acids (a1) relative to 100 mol% of the structural units derived from the polycarboxylic acids (a) can be calculated using the following formula: Content (mol%) of structural units derived from the cyclic structure-containing polycarboxylic acids (a1) = (content (mol) of structural units derived from the cyclic structure-containing polycarboxylic acids (a1) / content (mol) of structural units derived from the polycarboxylic acids (a)) × 100

[0025] Furthermore, the content of the structural units derived from the cyclic structure-containing polycarboxylic acids (a1) relative to the entire polyester resin (A) is preferably 3 to 50 mass%, more preferably 5 to 40 mass%, even more preferably 7 to 35 mass%, particularly preferably 10 to 30 mass%, and especially preferably 15 to 25 mass%. If the content of the structural units derived from the cyclic structure-containing polycarboxylic acids (a1) is too low, the heat resistance and moist heat resistance tend to be insufficient, while if it is too high, the compatibility with the polyepoxy compound (B) tends to decrease, resulting in insufficient optical properties, or the glass transition temperature tends to increase, resulting in insufficient tackiness, adhesive strength, and molding stability.

[0026] Examples of the cyclic structure-containing polycarboxylic acid (a1) include monocyclic polycarboxylic acids (a1-1) and polycyclic polycarboxylic acids (a1-2). Among these, in terms of excellent adhesive strength, molding stability, and optical properties, it is preferable that the cyclic structure-containing polycarboxylic acid (a1) contains a monocyclic polycarboxylic acid (a1-1), and it is particularly preferable that the cyclic structure-containing polycarboxylic acid (a1) is a monocyclic polycarboxylic acid (a1-1). Examples of the monocyclic polycarboxylic acid (a1-1) include aromatic monocyclic dicarboxylic acids such as terephthalic acids, isophthalic acids, and orthophthalic acids, and alicyclic monocyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acids, 1,3-cyclohexanedicarboxylic acids, and 1,2-cyclohexanedicarboxylic acids.

[0027] Furthermore, the monocyclic polycarboxylic acids (a-1) also include tri- or higher functional monocyclic polycarboxylic acids that are introduced into the polyester resin (A) for the purpose of imparting a branched skeleton or acid value. Examples of the tri- or higher functional monocyclic polycarboxylic acids include trimellitic acids, trimesic acids, and pyromellitic acids.

[0028] Among the monocyclic polycarboxylic acids (a1-1), monocyclic aromatic dicarboxylic acids such as terephthalic acids, isophthalic acids, and orthophthalic acids are preferred from the viewpoint of excellent heat resistance and moist heat resistance, and terephthalic acids and isophthalic acids are particularly preferred. Isophthalic acids are even more preferred from the viewpoint of reducing the crystallinity of the polyester resin (A) to provide excellent stability after dissolution in a solvent, and furthermore, providing excellent tackiness and adhesive strength.

[0029] The monocyclic polycarboxylic acids (a1-1) can also be classified into asymmetric monocyclic polycarboxylic acids and symmetric monocyclic polycarboxylic acids. From the viewpoint of reducing the crystallinity of the polyester resin (A), it is preferable that the polycarboxylic acid (a) contains an asymmetric monocyclic polycarboxylic acid, and from the viewpoint of excellent solvent dissolution stability, it is preferable that the polycarboxylic acid (a) contains both an asymmetric monocyclic polycarboxylic acid and a symmetric monocyclic polycarboxylic acid.

[0030] Examples of the asymmetric monocyclic polycarboxylic acids include isophthalic acids, orthophthalic acids, 1,3-cyclohexanedicarboxylic acids, and 1,2-cyclohexanedicarboxylic acids, and among these, isophthalic acids are particularly preferred because of their excellent reactivity and adhesive strength. Examples of the symmetric monocyclic polycarboxylic acids include terephthalic acids and 1,4-cyclohexanedicarboxylic acids.

[0031] When the polyester resin (A) contains a structural unit derived from a monocyclic polycarboxylic acid (a1-1), the content of the structural unit derived from the monocyclic polycarboxylic acid (a1-1) relative to 100 mol% of the structural units derived from the polycarboxylic acid (a) is preferably 30 mol% or more, more preferably 40 to 98 mol%, even more preferably 50 to 95 mol%, particularly preferably 55 to 90 mol%, and especially preferably 60 to 85 mol%. If the content of the structural unit derived from the monocyclic polycarboxylic acid (a1-1) is too low, the heat resistance and moist heat resistance tend to be insufficient, while if it is too high, the compatibility with the polyepoxy compound (B) tends to decrease, resulting in insufficient optical properties, or the glass transition temperature tends to increase, resulting in insufficient tackiness, adhesion, and molding stability.

[0032] Furthermore, when an asymmetric monocyclic polycarboxylic acid and a symmetric monocyclic polycarboxylic acid are used as the monocyclic polycarboxylic acids (a1-1), the content ratio (molar ratio) in the polyester resin (A) of structural units derived from the asymmetric monocyclic polycarboxylic acid / structural units derived from the symmetric monocyclic polycarboxylic acid is preferably 30 / 70 to 100 / 0, more preferably 40 / 60 to 95 / 5, particularly preferably 45 / 55 to 90 / 10, even more preferably 50 / 50 to 85 / 15, and particularly preferably 55 / 45 to 80 / 20.

[0033] In addition, the cyclic structure-containing polycarboxylic acid (a1) may contain a polycyclic polycarboxylic acid (a1-2) from the viewpoint of heat resistance and moist heat resistance. Examples of the polycyclic polycarboxylic acid (a1-2) include polycyclic aromatic dicarboxylic acids such as biphenyl dicarboxylic acids, naphthalenedicarboxylic acids, and dimethyl naphthalenedicarboxylic acids.

[0034] When the polyester resin (A) contains a structural unit derived from a polycyclic polycarboxylic acid (a1-2), the content of the structural unit derived from the polycyclic polycarboxylic acid (a1-2) relative to 100 mol% of the structural unit derived from the polycarboxylic acid (a1) is preferably 50 mol% or less, more preferably 40 mol% or less, even more preferably 30 mol% or less, particularly preferably 20 mol% or less, particularly preferably 10 mol% or less, and most preferably 5 mol% or less. If the content of the structural unit derived from the polycyclic polycarboxylic acid (a1-2) is too high, the transparency of the resin decreases, resulting in insufficient optical properties, or the glass transition temperature increases, resulting in insufficient tackiness, adhesive strength, and molding stability.

[0035] Furthermore, from the viewpoint of moist heat resistance and adhesive strength, the structural unit derived from the polycarboxylic acid (a) preferably contains a structural unit derived from a dimer acid (a2). Examples of the dimer acid (a2) include dimer acids (mainly those having 36 to 44 carbon atoms) derived by dimerizing unsaturated aliphatic acids such as oleic acid, linoleic acid, linolenic acid, and erucic acid, and hydrogenated products thereof. Among these, hydrogenated products are preferred from the viewpoint of suppressing gelation during the production of polyester-based resins.

[0036] When the polyester resin (A) contains structural units derived from dimer acids (a2), the content of the structural units derived from dimer acids (a2) relative to 100 mol% of the structural units derived from polycarboxylic acids (a) is preferably 70 mol% or less, more preferably 3 to 60 mol%, even more preferably 5 to 50 mol%, particularly preferably 10 to 45 mol%, and especially preferably 15 to 40 mol%. If the content of the structural units derived from dimer acids (a2) is too low, the adhesive strength and moist heat resistance tend to be insufficient, while if it is too high, the compatibility with the polyepoxy compound (B) tends to decrease, resulting in insufficient optical properties and insufficient solvent dissolution stability.

[0037] Furthermore, when the polyester resin (A) contains structural units derived from dimer acids (a2), the content of the structural units derived from dimer acids (a2) relative to the total mass of the polyester resin (A) is preferably 3 to 80 mass%, more preferably 5 to 70 mass%, even more preferably 10 to 60 mass%, particularly preferably 15 to 50 mass%, especially preferably 20 to 40 mass%, and most preferably 30 to 45 mass%. If the content of the structural units derived from dimer acids (a2) is too low, the adhesive strength and moist heat resistance tend to be insufficient, whereas if it is too high, the compatibility with the polyepoxy compound (B) tends to decrease, resulting in insufficient optical properties and insufficient solvent dissolution stability.

[0038] Furthermore, the structural unit derived from the polycarboxylic acid (a) may contain a structural unit derived from an aliphatic polycarboxylic acid from the viewpoints of adhesive strength and molding stability. Examples of the aliphatic polycarboxylic acid include malonic acids, dimethylmalonic acids, succinic acids, glutaric acids, adipic acids, trimethyladipic acids, pimelic acids, 2,2-dimethylglutaric acids, azelaic acids, sebacic acids, fumaric acids, maleic acids, itaconic acids, thiodipropionic acids, diglycolic acids, and 1,9-nonanedicarboxylic acids. These may be used alone or in combination of two or more. Among these, adipic acids, sebacic acids, and azelaic acids are particularly preferred from the viewpoints of lowering the glass transition temperature, thereby achieving excellent adhesive strength and molding stability, and further improving the optical properties of the resin.

[0039] When the polyester resin (A) contains structural units derived from aliphatic polycarboxylic acids, the content of the structural units derived from aliphatic polycarboxylic acids relative to 100 mol% of the structural units derived from polycarboxylic acids (a) is preferably 70 mol% or less, more preferably 3 to 60 mol%, even more preferably 5 to 50 mol%, particularly preferably 10 to 45 mol%, and especially preferably 15 to 40 mol%. If the content of the structural units derived from aliphatic polycarboxylic acids is too low, the adhesive strength and molding stability tend to be insufficient, while if it is too high, the heat resistance and moist heat resistance tend to be insufficient.

[0040] Furthermore, when imparting an acid value to the polyester resin (A), from the viewpoint of adhesive strength, it is preferable that the structural unit derived from the polycarboxylic acid (a) contains a structural unit derived from a trivalent or higher polycarboxylic acid having 0 or 1 acid anhydride group. The carboxyl group in the trivalent or higher polycarboxylic acid having 0 or 1 acid anhydride group preferably has a valence of 3 to 6, more preferably 3 to 4. Examples of the trivalent or higher polyvalent carboxylic acids having 0 or 1 acid anhydride group include trimellitic acid, trimesic acid, ethylene glycol bis (anhydrotrimellitate), glycerol tris (anhydrotrimellitate), trimellitic anhydride, pyromellitic dianhydride, oxydiphthalic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-diphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 4,4'- (hexafluoroisopropylidene) diphthalic dianhydride, and 2,2'-bis [(dicarboxyphenoxy) phenyl] propane dianhydride. Examples of the trivalent or higher polyvalent carboxylic acids having 0 or 1 acid anhydride group include aliphatic polyvalent carboxylic acids having 0 or 1 acid anhydride groups such as hydrogenated trimellitic anhydride. These may be used alone or in combination of two or more. Among these, aromatic polycarboxylic acids having a valence of 3 or more and having 0 or 1 acid anhydride group are preferred, and aromatic polycarboxylic acids having a valence of 3 or more and having 1 acid anhydride group are more preferred, with trimellitic anhydride being particularly preferred.

[0041] The polyester resin (A) may contain structural units derived from aromatic dicarboxylic acids having sulfonic acid groups, such as sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, and 5(4-sulfophenoxy)isophthalic acid, and structural units derived from aromatic dicarboxylic acid salts having sulfonate groups, such as their metal salts and ammonium salts. From the viewpoint of the moist heat resistance of the polyester resin (A), the content thereof is preferably 10 mol % or less, more preferably 5 mol % or less, particularly preferably 3 mol % or less, even more preferably 1 mol % or less, and most preferably 0 mol %, relative to 100 mol % of the structural units derived from the polyvalent carboxylic acids (a).

[0042] [Polyhydric alcohols (b)] Examples of the polyhydric alcohols (b) include aliphatic polyhydric alcohols (b1), dimer diols (b2), alicyclic polyhydric alcohols, aromatic polyhydric alcohols, bisphenol skeleton-containing polyhydric alcohols, etc. One or more types of the polyhydric alcohols (b) can be used.

[0043] In the present invention, the polyester resin (A) contains a structural unit derived from an aliphatic polyhydric alcohol (b1) as a structural unit derived from a polyhydric alcohol (b).

[0044] Examples of the aliphatic polyhydric alcohols (b1) include ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, 1,10-decanediol, 2-ethyl-2-butylpropanediol, 2,4-diethyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol. Among these, from the viewpoints of excellent hydrolysis resistance, solvent dissolution stability, and optical properties, aliphatic polyhydric alcohols having a hydrocarbon group in at least one side chain, such as 1,2-propylene glycol, 2-methyl-1,3-propanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, and 2,2,4-trimethyl-1,3-pentanediol, are preferred, with 2-methyl-1,3-propanediol and 3-methyl-1,5-pentanediol being particularly preferred, and 3-methyl-1,5-pentanediol being even more preferred from the viewpoint of excellent moist heat resistance and adhesive strength. Note that the aliphatic polyhydric alcohols having a hydrocarbon group in at least one side chain are those excluding the dimer diols (b2) described below.

[0045] The content of structural units derived from aliphatic polyhydric alcohols (b1) relative to 100 mol% of structural units derived from polyhydric alcohols (b) is preferably 5 to 95 mol%, more preferably 15 to 90 mol%, particularly preferably 25 to 85 mol%, even more preferably 35 to 80 mol%, and particularly preferably 45 to 75 mol%. If the content of structural units derived from aliphatic polyhydric alcohols (b1) is too low, the compatibility with polyepoxy compound (B) tends to decrease, resulting in insufficient optical properties and insufficient solvent dissolution stability. If the content is too high, the heat resistance, moist heat resistance, and adhesive strength tend to be insufficient.

[0046] The polyester resin (A) preferably contains a structural unit derived from a dimer diol (b2) as a structural unit derived from a polyhydric alcohol (b).

[0047] Examples of the dimer diols (b2) include dimer diols which are reduction products of dimer acids (mainly those having 36 to 44 carbon atoms) derived by dimerizing unsaturated aliphatic acids such as oleic acid, linoleic acid, linolenic acid, and erucic acid, and hydrogenated products thereof. Among these, hydrogenated products are preferred from the viewpoint of suppressing gelation during the production of the polyester resin (A).

[0048] When the polyester resin (A) contains structural units derived from dimer diols (b2), the content of the structural units derived from dimer diols (b2) relative to 100 mol% of the structural units derived from polyhydric alcohols (b) is preferably 3 to 95 mol%, more preferably 5 to 90 mol%, particularly preferably 4 to 80 mol%, even more preferably 5 to 70 mol%, particularly preferably 10 to 50 mol%, and most preferably 25 to 40 mol%. If the content of the structural units derived from dimer diols (b2) is too low, the adhesive strength and moist heat resistance tend to be insufficient, while if it is too high, the compatibility with the polyepoxy compound (B) tends to decrease, resulting in insufficient optical properties and insufficient solvent dissolution stability.

[0049] Furthermore, when the polyester resin (A) contains structural units derived from dimer diols (b2), the content of the structural units derived from dimer diols (b2) relative to the total weight of the polyester resin (A) is preferably 3 to 80% by weight, more preferably 5 to 70% by weight, even more preferably 10 to 60% by weight, particularly preferably 15 to 50% by weight, particularly preferably 18 to 40% by weight, and most preferably 30 to 45% by weight. If the content of the structural units derived from dimer diols (b2) is too low, the heat resistance, moist heat resistance, and adhesive strength tend to be insufficient, while if it is too high, the compatibility with the polyepoxy compound (B) tends to decrease, resulting in insufficient optical properties and insufficient solvent dissolution stability.

[0050] Examples of the alicyclic polyhydric alcohols include 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, tricyclodecanediol, tricyclodecanedimethanol, and spiroglycol.

[0051] Examples of the aromatic polyhydric alcohols include paraxylene glycol, metaxylene glycol, orthoxylene glycol, 1,4-phenylene glycol, and ethylene oxide adducts of 1,4-phenylene glycol.

[0052] Examples of the bisphenol skeleton-containing polyhydric alcohols include bisphenol A, bisphenol B, bisphenol E, bisphenol F, bisphenol AP, bisphenol BP, bisphenol P, bisphenol PH, bisphenol S, bisphenol Z, 4,4'-dihydroxybenzophenone, bisphenolfluorene, and hydrogenated products thereof, as well as glycols 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 groups of bisphenols.

[0053] Furthermore, in order to easily obtain a polymer having a desired molecular weight, the polyester resin (A) may contain, as a polyhydric alcohol (b), for example, polyester diol, polyether diol, polycaprolactone diol, polycarbonate diol, polybutadiene diol, polyisoprene diol, etc. These may be used alone or in combination of two or more kinds.

[0054] [Dimer Acids (a2), Dimer Diols (b2)] The polyester resin (A) preferably contains a structural unit derived from a dimer acid (a2) and / or a structural unit derived from a dimer diol (b2) from the viewpoints of moist heat resistance and adhesive strength.

[0055] When the polyester resin (A) contains structural units derived from dimer acids (a2) and / or structural units derived from dimer diols (b2), the total content of the structural units derived from dimer acids (a2) and dimer diols (b2) relative to the total polyester resin (A) is preferably 20 to 90% by mass, more preferably 30 to 85% by mass, particularly preferably 35 to 80% by mass, even more preferably 40 to 75% by mass, particularly preferably 45 to 70% by mass, and most preferably 50 to 65% by mass. If the total content of the structural units derived from dimer acids (a2) and dimer diols (b2) is too low, the adhesive strength and moist heat resistance tend to be insufficient, while if it is too high, the compatibility with the polyepoxy compound (B) tends to decrease, resulting in insufficient optical properties and insufficient solvent dissolution stability.

[0056] [Trifunctional or higher polycarboxylic acids and trifunctional or higher polyhydric alcohols] The polyester resin (A) preferably contains, as a branched skeleton, a structural unit derived from a trifunctional or higher polycarboxylic acid and / or a structural unit derived from a trifunctional or higher polyhydric alcohol. In particular, when a crosslinked structure is formed by reacting with a crosslinking agent, the polyester resin (A) contains a branched skeleton, which increases the crosslinking points of the polyester resin (A), allowing a pressure-sensitive adhesive with high cohesive strength to be efficiently obtained with a small amount of crosslinking agent. Note that the trifunctional or higher polycarboxylic acids used to introduce a branched skeleton into the polyester resin (A) are different from the polycarboxylic acids used in the depolymerization reaction described below.

[0057] Examples of the trifunctional or higher polyvalent carboxylic acids include trimellitic acid, trimesic acid, ethylene glycol bis(anhydrotrimellitate), glycerol tris(anhydrotrimellitate), trimellitic anhydride, pyromellitic dianhydride, oxydiphthalic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-diphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride, and 2,2'-bis[(dicarboxyphenoxy)phenyl]propane dianhydride. Examples of the trifunctional or higher polyhydric alcohols include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol. These trifunctional or higher polyvalent carboxylic acids and trifunctional or higher polyhydric alcohols can each be used alone or in combination of two or more.

[0058] When the polyester resin (A) contains structural units derived from trifunctional or higher polycarboxylic acids and / or structural units derived from trifunctional or higher polyhydric alcohols as branched skeletons, the content of the trifunctional or higher polycarboxylic acids relative to 100 mol% of the structural units derived from the polycarboxylic acids (a) is preferably 0.1 to 5 mol%, more preferably 0.3 to 4 mol%, even more preferably 0.5 to 3 mol%, and particularly preferably 1 to 2.5 mol%. Furthermore, the content of the trifunctional or higher polyhydric alcohol relative to 100 mol% of the structural units derived from the polyhydric alcohols (b) is preferably 0.1 to 5 mol%, more preferably 0.3 to 4 mol%, even more preferably 0.5 to 3 mol%, and particularly preferably 1 to 2.5 mol%. If the content of both or either of these is too high, the mechanical properties such as elongation at break of the coating film formed by application of the pressure-sensitive adhesive tend to decrease, resulting in a decrease in adhesive strength, and gelation also tends to occur during polymerization.

[0059] [Structural Units Derived from Cyclic Esters] The polyester resin (A) has structural units derived from polycarboxylic acids (a) and structural units derived from polyhydric alcohols (b), and may further contain structural units derived from cyclic esters.

[0060] Examples of the cyclic ester include aliphatic lactones such as lactide, β-propiolactone, β-butyrolactone, γ-butyrolactone, γ-hexanolactone, γ-octanolactone, δ-valerolactone, δ-hexalanolactone, δ-octanolactone, ε-caprolactone, δ-dodecanolactone, α-methyl-γ-butyrolactone, β-methyl-δ-valerolactone, glycolide, lactide, etc. These cyclic ester monomers can be used alone or in combination.

[0061] The content of the cyclic ester-derived structural units in the polyester resin (A) is preferably less than 140 mol%, more preferably less than 100 mol%, particularly preferably less than 60 mol%, even more preferably less than 30 mol%, particularly preferably less than 15 mol%, and most preferably 0 mol%, relative to 100 mol% of the structural units derived from the polycarboxylic acids (a). If the content of the cyclic ester-derived structural units is too high, the heat resistance, moist heat resistance, and solvent dissolution stability tend to be insufficient.

[0062] [Production of Polyester Resin (A)] The polyester resin (A) can be produced by a known method, for example, by subjecting a polycarboxylic acid (a) and a polyhydric alcohol (b) to an esterification reaction, optionally in the presence of a catalyst, to obtain a prepolymer, followed by polycondensation to obtain a polyester resin, and then introducing an acid value as needed.

[0063] The temperature for the esterification reaction between the polycarboxylic acids (a) and the polyhydric alcohols (b) is usually 180 to 280° C., and the reaction time is usually 60 minutes to 8 hours.

[0064] The temperature in the polycondensation is usually 220 to 280° C., and the reaction time is usually 20 minutes to 4 hours. The polycondensation is preferably carried out under reduced pressure.

[0065] Examples of methods for introducing an acid value into a polyester resin include methods for introducing a carboxy group into a polyester resin by an acid addition method or a depolymerization method after an esterification reaction or reduced-pressure polycondensation. Among these, when a carboxy group is introduced into the main chain terminal of a polyester resin, the depolymerization method is particularly preferred because it efficiently introduces a carboxy group, increases the molecular weight between crosslinking points with the polyepoxy compound (B), and provides excellent adhesive strength, heat resistance, and molding stability. Furthermore, when a carboxy group is introduced into the side chain of a polyester resin, the acid addition method is preferred.

[0066] When a carboxy group is introduced into the main chain terminal of a polyester resin by the depolymerization method, for example, a polycarboxylic acid (a) and a polyhydric alcohol (b) are subjected to an esterification reaction, optionally in the presence of a catalyst, to obtain a prepolymer, which is then subjected to polycondensation and further depolymerization.

[0067] For depolymerization, it is preferable to use a trivalent or higher polycarboxylic acid having 0 or 1 acid anhydride group in terms of adhesive strength. Examples of trivalent or higher polycarboxylic acids having 0 or 1 acid anhydride group include compounds such as trimellitic acid, trimellitic anhydride, hydrogenated trimellitic anhydride, and trimesic acid. Preferred are trivalent or higher polycarboxylic acids having 1 acid anhydride group in terms of being able to suppress a decrease in molecular weight, such as trimellitic anhydride and hydrogenated trimellitic anhydride, with trimellitic anhydride being particularly preferred.

[0068] The temperature for depolymerization is usually 200 to 260° C., and the reaction time is usually 10 minutes to 3 hours.

[0069] When producing polyester resin (A) by depolymerization, the molecular weight of the resin tends to decrease significantly if the content of structural units derived from trivalent or higher polycarboxylic acids having 0 or 1 acid anhydride group exceeds 20 mol% relative to 100 mol% of structural units derived from polycarboxylic acids (a). Therefore, the content of structural units derived from trivalent or higher polycarboxylic acids having 0 or 1 acid anhydride group relative to 100 mol% of structural units derived from polycarboxylic acids (a) is preferably 20 mol% or less, more preferably 1 to 15 mol%, particularly preferably 2 to 10 mol%, and even more preferably 3 to 8 mol%.

[0070] When the carboxyl group is introduced into the side chain of the polyester resin by the acid addition method, for example, a polycarboxylic acid (a) other than a polycarboxylic acid anhydride and a polyhydric alcohol (b) are subjected to an esterification reaction to obtain a prepolymer, and then the resulting hydroxyl group-containing prepolymer is reacted with a polycarboxylic acid anhydride to perform acid addition. Note that, when a monocarboxylic acid, a dicarboxylic acid, or a polyfunctional carboxylic acid compound is used in the acid addition method, a decrease in molecular weight may occur due to ester exchange, so it is preferable to use a compound having at least one carboxylic acid anhydride.

[0071] In addition, methods of acid addition and depolymerization include direct addition in bulk and addition of a polyester resin in solution. The reaction in bulk is fast, but adding a large amount can cause gelation, and the reaction occurs at high temperatures, so care must be taken to prevent oxidation by blocking oxygen gas. On the other hand, addition in solution is slow, but allows for the stable introduction of a large number of carboxyl groups.

[0072] Examples of the carboxylic acid anhydride include succinic anhydride, maleic anhydride, orthophthalic anhydride, 2,5-norbornene dicarboxylic acid anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic dianhydride, oxydiphthalic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride, 3,3',4,4'-diphenyltetracarboxylic acid dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic acid dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride, and 2,2'-bis[(dicarboxyphenoxy)phenyl]propane dianhydride.

[0073] When producing the polyester resin (A) by the acid addition method, if 15 mol % or more of the structural units derived from the polycarboxylic acids (a) are acid-added relative to 100 mol %, gelation may occur, and therefore it is preferable to add less than 15 mol % of the structural units derived from the polycarboxylic acids (a).

[0074] [Compositional Ratio of Polyester Resin (A)] In the present invention, the ratio of structural moieties derived from each component of the polyester resin (A) (compositional ratio) can be determined by a known method using NMR, for example, a method using a resonant frequency of 400 MHz. 1 H-NMR measurement (proton nuclear magnetic resonance spectroscopy), 13 It can be determined by C-NMR measurement (carbon-type nuclear magnetic resonance spectroscopy) or the like.

[0075] [Glass Transition Temperature of Polyester Resin (A)] The glass transition temperature of the polyester resin (A) used in the present invention is −75 to −20° C., preferably −70 to −22° C., more preferably −65 to −24° C., particularly preferably −60 to −26° C., even more preferably −55 to −28° C., especially preferably −50 to −30° C., and most preferably −45 to −35° C. If the glass transition temperature is too high, tackiness and adhesive strength tend to be insufficient, tensile properties tend to be reduced, and processability and molding stability tend to be insufficient, whereas if the glass transition temperature is too low, heat resistance and moist heat resistance tend to be insufficient.

[0076] The glass transition temperature can be measured using a differential scanning calorimeter as follows: the measurement temperature range is −90 to 100° C., and the temperature rise rate is 10° C. / min.

[0077] [Acid Value of Polyester Resin (A)] In the present invention, the polyester resin (A) is crosslinked by the polyepoxy compound (B) and has carboxy groups as crosslinking points. The acid value of the polyester resin (A) is 1.5 to 30 mgKOH / g, preferably 2 to 20 mgKOH / g, particularly preferably 2.5 to 15 mgKOH / g, even more preferably 3 to 12 mgKOH / g, particularly preferably 3.5 to 10 mgKOH / g, and most preferably 4 to 8 mgKOH / g. If the acid value is too low, the number of crosslinking points will be small, which tends to result in insufficient heat resistance. If the acid value is too high, the number of crosslinking points will be too large, which tends to result in insufficient adhesive strength and molding stability, and the amount of polyepoxy compound (B) required for crosslinking will be large, which tends to result in insufficient optical properties.

[0078] The definition and measurement method of the acid value are as follows. The acid value (mg KOH / g) can be determined by dissolving 1 g of the polyester resin (A) in 30 g of a mixed solvent of toluene / methanol (for example, a volume ratio of toluene / methanol = 7 / 3) and performing neutralization titration in accordance with JIS K 0070. In the present invention, the acid value of the polyester resin (A) is determined by the content of carboxy groups in the resin.

[0079] [Hydroxyl value of polyester resin (A)] The hydroxyl value of the polyester resin (A) is preferably 10 mgKOH / g or less, particularly 5 mgKOH / g or less, further 3 mgKOH / g or less, more preferably 2 mgKOH / g or less, particularly preferably 1 mgKOH / g or less, and most preferably 0.5 mgKOH / g or less. If the hydroxyl value is too high, the number of crosslinking points with the polyepoxy compound (B) will decrease, and the heat resistance and moist heat resistance will tend to be insufficient.

[0080] The hydroxyl value of the polyester resin (A) is determined by neutralization titration in accordance with JIS K 0070.

[0081] [Ester Bond Concentration of Polyester Resin (A)] The ester bond concentration of the polyester resin (A) used in the present invention is preferably 1.5 to 8 mmol / g, more preferably 2 to 7.5 mmol / g, even more preferably 2.5 to 7 mmol / g, particularly preferably 3 to 6.5 mmol / g, especially preferably 3.5 to 6 mmol / g, and most preferably 4 to 5.5 mmol / g. If the ester bond concentration is too high, the heat resistance and moist heat resistance tend to be insufficient, while if the ester bond concentration is too low, the compatibility with the polyepoxy compound (B) tends to decrease, resulting in insufficient optical properties.

[0082] The definition and measurement method of the ester bond concentration are as follows. The ester bond concentration (mmol / g) refers to the number of moles of ester bonds in 1 g of polyester resin (A), and can be calculated, for example, from the amounts charged. This calculation is calculated by dividing the smaller number of moles of the charged amounts of polycarboxylic acids (a) and polyhydric alcohols (b) by the total mass of the polyester resin (A), and an example of the calculation formula is shown below. Note that when the charged amounts of polycarboxylic acids (a) and polyhydric alcohols (b) are equal in molar amount, either of the calculation formulas below may be used. Furthermore, when a monomer having both a carboxyl group and a hydroxyl group is used, or when polyester is produced from caprolactone or the like, the calculation method will be changed appropriately.

[0083] (When the amount of polycarboxylic acids (a) is less than the amount of polyhydric alcohols (b)) Ester group concentration (mmol / g) = [(A1 / a1 × m1 + A2 / a2 × m2 + A3 / a3 × m3 ...) / Z] × 1000 A: Amount (g) of polycarboxylic acids (a) charged a: Molecular weight of polycarboxylic acids (a) m: Number of carboxy groups per molecule of polycarboxylic acids (a) Z: Finished mass (g)

[0084] (When the amount of polyhydric alcohols (b) is less than the amount of polycarboxylic acids (a)) Ester group concentration (mmol / g) = [(B1 / b1 x n1 + B2 / b2 x n2 + B3 / b3 x n3 ...) / Z] x 1000 B: Amount of polyhydric alcohols (b) charged (g) b: Molecular weight of polyhydric alcohols (b) n: Number of hydroxyl groups per molecule of polyhydric alcohols (b) Z: Finished mass (g)

[0085] The ester bond concentration can be measured by a known method using NMR or the like, for example, 1 H-NMR measurement (proton nuclear magnetic resonance spectroscopy), 13 It can also be measured by C-NMR measurement (carbon-type nuclear magnetic resonance spectroscopy).

[0086] [Peak Top Molecular Weight (Mp) and Weight Average Molecular Weight (Mw) of Polyester Resin (A)] The peak top molecular weight (Mp) of the polyester resin (A) is preferably 5,000 to 150,000, more preferably 10,000 to 120,000, particularly preferably 20,000 to 100,000, even more preferably 30,000 to 90,000, and particularly preferably 40,000 to 80,000. If the peak top molecular weight (Mp) is too low, the cohesive strength tends to be insufficient, and the heat resistance and wet heat durability tend to be insufficient. On the other hand, if the peak top molecular weight (Mp) is too high, the adhesive strength tends to be insufficient, or the compatibility with the polyepoxy compound (B) tends to be reduced, resulting in insufficient optical properties.

[0087] The weight-average molecular weight (Mw) of the polyester resin (A) is preferably 5,000 to 500,000, more preferably 10,000 to 300,000, particularly preferably 20,000 to 200,000, even more preferably 30,000 to 150,000, and particularly preferably 50,000 to 130,000. If the weight-average molecular weight (Mw) is too low, the cohesive strength tends to be insufficient, and the heat resistance and wet heat durability tend to be insufficient. On the other hand, if the weight-average molecular weight (Mw) is too high, the adhesive strength tends to be insufficient, and the compatibility with the polyepoxy compound (B) tends to be reduced, resulting in insufficient optical properties.

[0088] The peak top molecular weight (Mp) and the weight average molecular weight (Mw) were measured as follows: The peak top molecular weight (Mp) and the weight average molecular weight (Mw) were measured using a high performance liquid chromatograph (manufactured by Tosoh Corporation, "HLC-8320GPC") with a column (TSKgel SuperMultipore HZ-M (exclusion limit molecular weight: 2 × 10 6 The theoretical plate number: 16,000 plates / tube, filler material: styrene-divinylbenzene copolymer, filler particle size: 4 μm) are measured in series using two tubes, and the molecular weight can be calculated in terms of standard polystyrene.

[0089] In the present invention, the polyester resin (A) is preferably an amorphous polyester resin in terms of solvent solubility, solution stability, tackiness, optical properties, etc. If the polyester resin (A) is crystalline, the solvent solubility, solution stability, tackiness, molding stability, optical properties, etc. tend to be insufficient. The amorphous nature can be confirmed by a differential scanning calorimeter, and refers to, for example, the absence of an endothermic peak due to crystalline melting when measured at a measurement temperature range of −90 to 400°C and a temperature rise rate of 10°C / min. The measurement temperature range and temperature rise rate can be appropriately changed depending on the sample.

[0090] The heat of crystalline fusion of the polyester resin (A) when crystallized is 35 J / g or less, preferably 20 J / g or less, particularly preferably 10 J / g or less, particularly preferably 5 J / g or less, more preferably 3 J / g or less, and most preferably 1 J / g or less. When the heat of crystalline fusion is 0 J / g, the polyester resin (A) is amorphous, which is preferable in terms of solvent solubility, solution stability, tackiness, optical properties, etc.

[0091] Furthermore, the polyester resin (A) is preferably made from plant-derived raw materials and has a biomass degree in order to reduce the burden on the global environment. The biomass degree of the polyester resin (A) is preferably 10% or more, more preferably 20% or more, particularly preferably 30% or more, even more preferably 40% or more, particularly preferably 50% or more, and most preferably 60% or more. The upper limit is 100%. If the biomass degree is low, the reduction in the burden on the global environment tends to be insufficient.

[0092] Here, the biomass degree of the polyester resin (A) refers to the mass ratio of the plant-derived raw materials used in producing the polyester resin (A) incorporated into the resin relative to the total mass of the polyester resin (A), and is calculated as follows. The biomass degrees of the polycarboxylic acids (a) and polyhydric alcohols (b) are determined as weighted averages of their respective biomass degrees. It is sufficient if the value obtained by any of the following calculation methods falls within the above-mentioned range.

[0093] (Calculation Method) Biomass ratio (%) = [(number of moles of carbon of plant-derived monomer calculated from the molar ratio of polycarboxylic acids (a) and polyhydric alcohols (b) in polyester resin (A)) / (number of moles of carbon of all constituent monomers in polyester resin (A))] × 100

[0094] The biomass ratio can also be determined by analyzing the composition ratio by NMR and calculating the carbon number of the plant-derived monomer / the total carbon number.

[0095] Furthermore, the biomass degree can also be measured by the method described in "Technology for Determining the Origin of Biofuels Using Natural Radioactive Carbon C-14," Tokyo Metropolitan Industrial Technology Research Center Research Report, No. 4, 2009.

[0096] In the present invention, it is preferable that the polyester resin (A) is soluble in non-petroleum organic solvents and non-aldehyde organic solvents in view of VOC emission regulations. Insufficient solubility in such organic solvents tends to increase the burden on the human body and the global environment, make preparation of the present pressure-sensitive adhesive composition difficult, and result in insufficient solution stability after dissolution.

[0097] Examples of the non-petroleum organic solvent and the non-aldehyde organic solvent include ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, alcohol solvents such as methyl alcohol, ethyl alcohol, isopropyl alcohol, and isobutyl alcohol, ester solvents such as ethyl acetate and n-butyl acetate, acetate solvents such as cellosolve acetate and methoxy acetate, and mixtures of two or more of these solvents. Among these, ketone solvents and ester solvents are preferred, and particularly preferred are methyl ethyl ketone, cyclohexanone, and ethyl acetate, and even more preferred are methyl ethyl ketone and ethyl acetate because of their low boiling points and excellent drying efficiency.

[0098] <Polyepoxy Compound (B)> The present pressure-sensitive adhesive composition further contains a polyepoxy compound (B) as a crosslinking agent. By including the polyepoxy compound (B) in the present pressure-sensitive adhesive composition, the epoxy groups in the polyepoxy compound (B) react with the carboxy groups in the polyester resin (A) to crosslink (cure), thereby obtaining a pressure-sensitive adhesive that not only has excellent adhesive strength but also excellent heat resistance. The polyepoxy compound (B) refers to a compound having at least two epoxy groups in its molecule.

[0099] Examples of the polyepoxy compound (B) include glycidyl amine types such as tetraglycidyl diaminodiphenylmethane, triglycidyl p-aminophenol, tetraglycidyl bisaminomethylcyclohexane, and N,N,N',N'-tetraglycidyl-m-xylenediamine; bifunctional glycidyl ether types such as bisphenol A diglycidyl ether, bisphenol S diglycidyl ether, and brominated bisphenol A diglycidyl ether; polyfunctional glycidyl ether types such as phenol novolac glycidyl ether and cresol novolac glycidyl ether; glycidyl ester types such as hexahydrophthalic acid glycidyl ester and dimer acid glycidyl ester; and alicyclic or aliphatic epoxides such as triglycidyl isocyanurate, 3,4-epoxycyclohexylmethylcarboxylate, epoxidized polybutadiene, and epoxidized soybean oil. One or more types of polyepoxy compounds (B) can be used.

[0100] The present pressure-sensitive adhesive composition preferably contains a nitrogen-containing polyepoxy compound (nitrogen-containing polyepoxy compound) as the polyepoxy compound (B), in that it can cure a coating film of the pressure-sensitive adhesive composition at low temperatures. Particularly preferred are aromatic glycidylamine-type polyepoxy compounds such as tetraglycidyldiaminodiphenylmethane and triglycidyl paraaminophenol, and aliphatic glycidylamine-type polyepoxy compounds such as 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane and N,N,N',N'-tetraglycidyl-m-xylenediamine, and aliphatic glycidylamine-type polyepoxy compounds such as 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane and N,N,N',N'-tetraglycidyl-m-xylenediamine are preferred in that they have excellent low-temperature curing properties.

[0101] The equivalent weight of the epoxy groups in the polyepoxy compound (B) relative to the carboxy groups in the polyester resin (A) is preferably 0.3 to 5 equivalents, more preferably 0.5 to 4 equivalents, even more preferably 0.7 to 3.5 equivalents, even more preferably 0.9 to 3.0 equivalents, particularly preferably 1.0 to 2.8 equivalents, especially preferably 1.2 to 2.6 equivalents, especially more preferably 1.4 to 2.4 equivalents, and most preferably 1.6 to 2.2 equivalents. If the equivalent weight is too large, the polyepoxy compound (B) will remain unincorporated into the crosslinks, tending to result in insufficient optical properties and heat resistance. On the other hand, if the equivalent weight is too small, the crosslink density will be low, tending to result in insufficient heat resistance, moist heat resistance, and adhesive strength.

[0102] The equivalent weight of epoxy groups relative to carboxy groups (COOH) can be calculated from the acid value of the polyester resin (A) and the epoxy equivalent weight (g / eq) of the blended polyepoxy compound (B) using the following formula: Equivalent weight of epoxy groups relative to COOH = (e ÷ WPE) / (AV ÷ 56.1 ÷ 1000 × P) e: mass (g) of the polyepoxy compound (B) used in the blend WPE: epoxy equivalent weight (g / eq) of the polyepoxy compound (B) AV: acid value (mg KOH / g) of the polyester resin (A) P: mass (g) of the polyester resin (A) used in the blend

[0103] The epoxy equivalent (WPE) of the polyepoxy compound (B) is preferably 500 g / eq or less, more preferably 350 g / eq or less, even more preferably 250 g / eq or less, particularly preferably 200 g / eq or less, and especially preferably 150 g / eq or less. If the epoxy equivalent of the polyepoxy compound (B) is too high, the crosslink density after curing decreases, resulting in insufficient heat resistance, and the optical properties tend to be insufficient because a large amount of the polyepoxy compound (B) needs to be added to increase the crosslink density. The lower limit of the epoxy equivalent (WPE) of the polyepoxy compound (B) is usually 50 g / eq or more. In the present invention, the "epoxy equivalent (WPE)" is defined as "the mass of an epoxy resin containing one equivalent of epoxy groups" and can be measured in accordance with JIS K 7236.

[0104] The amount of epoxy compound (B) is preferably 0.1 to 15 parts by mass, more preferably 0.2 to 10 parts by mass, even more preferably 0.3 to 5 parts by mass, particularly preferably 0.5 to 4.5 parts by mass, especially preferably 0.7 to 4 parts by mass, and most preferably 1 to 3.5 parts by mass, per 100 parts by mass of polyester resin (A). If the amount of polyepoxy compound (B) is too high, some of the polyepoxy compound (B) will remain unincorporated into crosslinks, resulting in insufficient optical properties and heat resistance. If the amount is too low, the crosslink density will be low, resulting in insufficient heat resistance, moist heat resistance, and adhesive strength.

[0105] <Polyisocyanate Compound (C)> From the viewpoint of moist heat resistance, the present pressure-sensitive adhesive composition may contain a polyisocyanate compound (C) as a crosslinking agent. The polyisocyanate compound (C) refers to a compound having at least two isocyanate groups in the molecule.

[0106] Examples of the polyisocyanate compound (C) include aromatic diisocyanate compounds such as tolylene diisocyanate compounds such as 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, xylylene diisocyanate compounds such as 1,3-xylylene diisocyanate, diphenylmethane compounds such as diphenylmethane-4,4-diisocyanate, and naphthalene diisocyanate crosslinking agents such as 1,5-naphthalene diisocyanate; isophorone diisocyanate, 1,4-cyclohexane diisocyanate, 4,4'-dicyclohexyl Examples of the polyisocyanate compound (C) include alicyclic diisocyanate compounds such as methane diisocyanate, methylcyclohexane diisocyanate, isopropylidenedicyclohexyl-4,4'-diisocyanate, 1,3-diisocyanatomethylcyclohexane, and norbornane diisocyanate; aliphatic diisocyanate compounds such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate; and adducts, biuret compounds, and isocyanurates of the aromatic diisocyanate compounds, alicyclic diisocyanate compounds, and aliphatic diisocyanate compounds. The polyisocyanate compound (C) may also be one in which the isocyanate moiety is blocked with phenol, lactam, or the like. These polyisocyanate compounds (C) may be used alone or in combination of two or more. Among these, from the viewpoint of optical properties and heat resistance, alicyclic diisocyanate compounds and aliphatic diisocyanate compounds are preferred, aliphatic diisocyanate compounds are particularly preferred, and isocyanurates of hexamethylene diisocyanate are even more preferred.

[0107] The equivalent weight of the isocyanate groups of the polyisocyanate compound (C) relative to the hydroxyl groups of the polyester resin (A) is preferably 3 equivalents or less, more preferably 2 equivalents or less, even more preferably 1.5 equivalents or less, particularly preferably 1 equivalent or less, and especially preferably 0.5 equivalents or less. If the equivalent weight is too large, some of the polyisocyanate compound (C) will remain unincorporated into crosslinks, resulting in insufficient optical properties and an increased urethane bond concentration, which tends to result in insufficient heat resistance.

[0108] When the pressure-sensitive adhesive composition contains a polyisocyanate compound (C), the content thereof is preferably 5 parts by mass or less, more preferably 4 parts by mass or less, even more preferably 3 parts by mass or less, particularly preferably 2 parts by mass or less, especially preferably 1.5 parts by mass or less, and most preferably 1 part by mass or less, relative to 100 parts by mass of the polyester resin (A). If the amount of the polyisocyanate compound added is too large, some of the polyisocyanate compound (C) will remain unincorporated into crosslinks, resulting in insufficient optical properties and a tendency for the heat resistance to decrease due to an increased urethane bond concentration.

[0109] <Carbodiimide Compound> The present pressure-sensitive adhesive composition may contain a carbodiimide compound from the viewpoint of moist heat resistance.

[0110] As the carbodiimide compound, a known carbodiimide having one or more carbodiimide groups (—N═C═N—) in the molecule may typically be used. However, 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. In particular, a compound having three or more, even five or more, and especially seven or more carbodiimide groups in the molecule is preferred. The number of carbodiimide groups in the molecule is typically 50 or less. If the number of carbodiimide groups is too large, the molecular structure tends to become too large, resulting in reduced compatibility and insufficient optical properties. Alternatively, a high-molecular-weight polycarbodiimide produced by a decarboxylation condensation reaction of a diisocyanate in the presence of a carbodiimidization catalyst may also be used.

[0111] Examples of such high molecular weight polycarbodiimides include those obtained by decarboxylation condensation reaction of the following diisocyanates: 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, tetramethylxylylene diisocyanate, and the like, which may be used alone or in combination of two or more.

[0112] When the pressure-sensitive adhesive composition contains a carbodiimide compound, the content thereof is preferably 5 parts by mass or less, more preferably 4 parts by mass or less, even more preferably 3 parts by mass or less, particularly preferably 2 parts by mass or less, especially preferably 1 part by mass or less, and most preferably 0.5 parts by mass or less, relative to 100 parts by mass of the polyester resin (A). If the amount of the carbodiimide compound added is too large, an excess amount of the carbodiimide compound will remain that is not incorporated into crosslinking, which tends to result in insufficient optical properties or to inhibit crosslinking between the polyester resin (A) and the polyepoxy compound (B), resulting in insufficient heat resistance.

[0113] <Metal Chelate Compound> The pressure-sensitive adhesive composition may contain a metal chelate compound as a crosslinking agent from the viewpoint of moist heat resistance. Examples of the metal chelate compound include metal alkoxides such as tetraethyl titanate, tetraethyl zirconate, and aluminum isopropionate; metal chelate compounds of acetylacetone, acetoacetate, and ethylenediaminetetraacetic acid coordination compounds of polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium; acetate-ammonium complex salts; and ammonium-carbonate complex salts. These metal chelate compounds may be used alone or in combination.

[0114] When the pressure-sensitive adhesive composition contains a metal chelate compound, the content thereof is preferably 5 parts by mass or less, more preferably 4 parts by mass or less, even more preferably 3 parts by mass or less, particularly preferably 2 parts by mass or less, especially preferably 1 part by mass or less, and most preferably 0.5 parts by mass or less, per 100 parts by mass of the polyester resin (A). If the amount of such a metal chelate compound added is too large, some of the metal chelate compound will remain unincorporated into the crosslinking, which may result in insufficient optical properties or inhibit crosslinking between the polyester resin (A) and the polyepoxy compound (B), resulting in insufficient heat resistance.

[0115] <Tackifying Resin> The present pressure-sensitive adhesive composition may contain a tackifying resin in order to improve adhesive properties.

[0116] The tackifier resin is not particularly limited, and conventionally known resins can be used. Examples of the tackifier resin include hydrocarbon resins, terpene resins, phenolic resins, rosin resins, xylene resins, epoxy resins, polyamide resins, ketone resins, and elastomer resins. These may be used alone or in combination of two or more. Among these, hydrocarbon tackifier resins and terpene resins are preferred because of their compatibility with the polyester resin (A) and excellent heat resistance.

[0117] Examples of the hydrocarbon-based tackifying resin include various hydrocarbon-based resins such as aliphatic hydrocarbon resins, aromatic hydrocarbon resins, aliphatic cyclic hydrocarbon resins, aliphatic / aromatic petroleum resins (styrene-olefin copolymers, etc.), aliphatic / alicyclic petroleum resins, hydrogenated hydrocarbon resins, coumarone resins, and coumarone-indene resins.

[0118] Examples of the terpene resin include terpene resins, terpene phenol resins, and aromatic-modified terpene resins. Specifically, α-pinene polymers, β-pinene polymers, dipentene polymers, and terpene resins obtained by phenol-modifying, aromatic-modifying, hydrogen-modifying, or hydrocarbon-modifying these polymers can be used. Furthermore, terpene phenol resins are preferred because of their excellent compatibility with the polyester resin (A) and excellent heat resistance.

[0119] Examples of the phenolic resin that can be used include condensates of formaldehyde with various phenols such as phenol, m-cresol, 3,5-xylenol, p-alkylphenol, and resorcinol.Furthermore, resol obtained by subjecting the phenols and formaldehyde to an addition reaction in the presence of an alkali catalyst, novolak obtained by subjecting the phenols and formaldehyde to a condensation reaction in the presence of an acid catalyst, and rosin-modified phenolic resin obtained by adding phenol to rosins such as unmodified or modified rosin or derivatives thereof in the presence of an acid catalyst, followed by thermal polymerization.

[0120] Examples of the rosin-based resin include rosin resin, polymerized rosin resin, hydrogenated rosin resin, rosin ester resin, hydrogenated rosin ester resin, rosin phenol resin, and polymerized rosin ester. Specific examples of the rosin resin that can be used include unmodified rosins (raw rosins) such as gum rosin, wood rosin, and tall oil rosin, modified rosins obtained by hydrogenating, disproportionating, polymerizing, or otherwise chemically modifying these, and derivatives of these.

[0121] From the viewpoint of moist heat resistance, the tackifier resin preferably has an acid value of 30 mgKOH / g or less, particularly 15 mgKOH / g or less, further 10 mgKOH / g or less, particularly 6 mgKOH / g or less, and most preferably 3 mgKOH / g. When multiple types of tackifier resins are used in combination, the average of their acids is preferably within the above range.

[0122] The softening point of the tackifier resin (measured, for example, by the ring and ball method) is preferably 60 to 170° C., particularly 80 to 160° C., and more preferably 100 to 150° C. If the softening point is within the above range, tackiness and adhesive strength can be improved, which is preferable.

[0123] In order to protect the global environment, the tackifier resin is preferably derived from plants, such as terpene resins and rosin resins.

[0124] When the pressure-sensitive adhesive composition contains a tackifier, the content thereof is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 15 parts by mass or less, particularly preferably 10 parts by mass or less, and especially preferably 5 parts by mass or less, relative to 100 parts by mass of the polyester resin (A). When the content is within the above range, tackiness and adhesive strength can be improved, which is preferable; if the content is too high, the glass transition temperature of the pressure-sensitive adhesive increases, and tackiness, adhesive strength, and molding stability tend to be insufficient.

[0125] [Catalyst] The present pressure-sensitive adhesive composition may contain a catalyst to promote crosslinking (curing) by the polyepoxy compound (B) at a low temperature.

[0126] Examples of such catalysts include imidazole compounds such as 2-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, and 1-cyanoethyl-2-ethyl-4-methylimidazole; triethylamine, triethylenediamine, N'-methyl-N-(2-dimethylaminoethyl)piperazine, 1,8-diazabicyclo(5,4,0)-undecene-7,1,5-diamine; Examples include tertiary amines such as azabicyclo(4,3,0)-nonene-5,6-dibutylamino-1,8-diazabicyclo(5,4,0)-undecene-7; and compounds obtained by converting these tertiary amines into amine salts with phenol, octylic acid, quaternized tetraphenylborate salts, etc.; cationic catalysts such as triallylsulfonium hexafluoroantimonate and diaryliodonium hexafluoroantimonate; and triphenylphosphine. Among these, tertiary amines such as 1,8-diazabicyclo(5,4,0)-undecene-7 and 1,5-diazabicyclo(4,3,0)-nonene-5,6-dibutylamino-1,8-diazabicyclo(5,4,0)-undecene-7; and compounds obtained by converting these tertiary amines into amine salts with phenol, octylic acid, quaternized tetraphenylborate salts, etc. are preferred in terms of thermosetting properties, heat resistance, adhesion to metals, and storage stability after blending. These catalysts may be used alone or in combination.

[0127] When the pressure-sensitive adhesive composition contains a catalyst, the amount of the catalyst is preferably 0.01 to 1 part by mass per 100 parts by mass of the polyester resin (A). When the content is within this range, a pressure-sensitive adhesive with a high degree of crosslinking can be obtained by reacting the polyester resin (A) with the polyepoxy compound (B) at a low temperature in a short time.

[0128] <Antioxidant (D)> The present pressure-sensitive adhesive composition preferably contains an antioxidant (D) from the viewpoint of increasing the heat resistance of the polyester resin (A).

[0129] Examples of the antioxidant (D) include hindered phenol-based antioxidants, amine-based antioxidants, sulfur-based antioxidants, and phosphoric acid-based antioxidants. Among these, at least one selected from the group consisting of hindered phenol-based antioxidants, amine-based antioxidants, and phosphoric acid-based antioxidants is preferred, and antioxidant (D) consisting of a hindered phenol-based compound is particularly preferred. Examples of the hindered phenol-based antioxidant include antioxidants having a hindered phenol structure in which a group with large steric hindrance, such as a tertiary butyl group, is bonded to at least one carbon atom adjacent to the carbon atom on the aromatic ring to which the phenolic hydroxyl group is bonded.

[0130] When the pressure-sensitive adhesive composition contains an antioxidant (D), the blending amount thereof is preferably 0.001 to 5 parts by mass, more preferably 0.01 to 3 parts by mass, even more preferably 0.02 to 2 parts by mass, particularly preferably 0.03 to 1 part by mass, and especially preferably 0.05 to 0.5 parts by mass, relative to 100 parts by mass of the polyester resin (A). If the content is too low, heat resistance tends to be insufficient, and if the content is too high, optical properties tend to be insufficient.

[0131] <Adhesive Composition> In addition to the polyester resin (A), polyepoxy compound (B), polyisocyanate compound (C), carbodiimide compound, metal chelate compound, catalyst, tackifier resin, and antioxidant (D), the adhesive composition may contain other components, such as plasticizers, UV absorbers, stabilizers, antistatic agents, silane coupling agents, fluxes, flame retardants, dispersants, emulsifiers, antifoaming agents, leveling agents, ion trapping agents, inorganic or organic fillers, powders such as metal powders and pigments, or particulate additives, as long as the effects of the present invention are not impaired. These may be used alone or in combination of two or more. Furthermore, the adhesive composition may contain small amounts of impurities contained in the manufacturing raw materials of the components of the adhesive composition.

[0132] When the present pressure-sensitive adhesive composition contains the additive, the content thereof is preferably 70 mass % or less, more preferably 0.001 to 50 mass %, particularly preferably 0.005 to 30 mass %, and even more preferably 0.01 to 10 mass %, of the total pressure-sensitive adhesive composition.

[0133] The content of the polyester resin (A) in the present pressure-sensitive adhesive composition is usually 70% by mass or more, more preferably 80 to 99.5% by mass, particularly preferably 85 to 99% by mass, even more preferably 90 to 98.5% by mass, and particularly preferably 95 to 98% by mass.

[0134] Such a pressure-sensitive adhesive composition can be obtained, for example, by preparing the polyester resin (A), the polyepoxy compound (B), and necessary optional components, etc., and mixing and dispersing them during the production of the polyester resin (A), or by mixing them into a solution of the polyester resin (A) dissolved in an organic solvent and dispersing them using a mixing roller or the like.

[0135] <Solvent> The present PSA composition may contain a solvent to appropriately adjust the viscosity of the PSA composition and to facilitate handling when forming a coating film. The solvent is used to ensure handleability and workability when molding the PSA composition, and there are no particular limitations on the amount used.

[0136] Examples of the solvent include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; esters such as ethyl acetate; ethers such as ethylene glycol monomethyl ether; amides such as N,N-dimethylformamide and N,N-dimethylacetamide; alcohols such as methanol and ethanol; alkanes such as hexane and cyclohexane; and aromatics such as toluene and xylene. Among these, ketone-based solvents and ester-based solvents are preferred from the viewpoint of VOC emission regulations, and methyl ethyl ketone, cyclohexanone, and ethyl acetate are particularly preferred, and methyl ethyl ketone and ethyl acetate are even more preferred because they have low boiling points and excellent drying efficiency. The above-mentioned solvents may be used alone, or two or more may be mixed in any combination and ratio.

[0137] <Adhesive> A polyester-based adhesive according to one embodiment of the present invention (hereinafter sometimes referred to as "the adhesive") is obtained by crosslinking the adhesive composition, and has excellent adhesive strength, heat resistance, moist heat resistance, and optical properties. "Crosslinking" in the present invention means intentionally crosslinking the adhesive composition by heat and / or light, etc., and the degree of crosslinking can be controlled depending on the desired physical properties and application.

[0138] The degree of crosslinking can be confirmed by the gel fraction of the PSA, with a gel fraction of preferably 20 to 100%, more preferably 30 to 98%, even more preferably 40 to 95%, particularly preferably 50 to 90%, especially preferably 55 to 85%, and most preferably 60 to 80%. If the gel fraction is too low, the heat resistance, holding power, adhesive strength, and wet heat durability tend to be insufficient, while if it is too high, the tackiness and adhesive strength tend to be insufficient. The gel fraction serves as a measure of the degree of crosslinking and is calculated, for example, by the following method. Specifically, a PSA sheet (without a release sheet) comprising a PSA layer formed on a polymer sheet substrate (e.g., PET film) is wrapped in a 200-mesh SUS wire mesh and immersed in toluene at 23°C for 24 hours. The gel fraction is calculated as the mass percentage of the insoluble PSA component remaining in the wire mesh after immersion relative to the mass of the PSA component before immersion. The mass of the substrate is subtracted from this calculation.

[0139] A pressure-sensitive adhesive layer is then formed from this pressure-sensitive adhesive, and a pressure-sensitive adhesive sheet having such a pressure-sensitive adhesive layer can be obtained. Note that in the present invention, the term "sheet" is used to include the meaning of "film" and "tape."

[0140] <Adhesive Sheet> A pressure-sensitive adhesive sheet according to one embodiment of the present invention (hereinafter sometimes referred to as "the present pressure-sensitive adhesive sheet") can be produced, for example, as follows. Such a pressure-sensitive adhesive sheet can be produced according to a publicly known general pressure-sensitive adhesive sheet production method, for example, by applying the present pressure-sensitive adhesive composition to a substrate, drying and crosslinking, laminating a release sheet to the pressure-sensitive adhesive layer surface opposite the substrate, and optionally curing, thereby obtaining the present pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing a pressure-sensitive adhesive on the substrate. Such a pressure-sensitive adhesive layer is preferably formed on one or both sides of the substrate.

[0141] Alternatively, the present pressure-sensitive adhesive sheet can be obtained by coating the present pressure-sensitive adhesive composition on a release sheet, drying and crosslinking the composition, laminating a substrate to the surface of the pressure-sensitive adhesive layer opposite the release sheet, and optionally curing the composition.

[0142] Alternatively, a substrate-less double-sided PSA sheet can be produced by forming a PSA layer on a release sheet and then laminating another release sheet to the opposite side of the PSA layer.

[0143] 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.

[0144] 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; and cellulose triacetate. Examples of the substrate include a sheet made of at least one synthetic resin selected from the group consisting of cellulose-based resins such as cellulose esters and cellophane; acrylic resins such as polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate, and polybutyl acrylate; fluorine-based resins; polystyrene; polycarbonate; acrylonitrile-butadiene-styrene copolymers; acrylonitrile-styrene-acrylic acid ester copolymers; polyarylates; polyimides; cycloolefin polymers; and urethane acrylate resins; metal foils such as aluminum, copper, and iron; paper such as fine paper and glassine paper; and woven and nonwoven fabrics made of glass fiber, natural fiber, synthetic fiber, etc. These substrates can be used as a single layer or as a multilayer body in which two or more types are laminated.

[0145] Among these, substrates made of polyethylene terephthalate, acrylic resins, polycarbonate, acrylonitrile-butadiene-styrene copolymers, acrylonitrile-styrene-acrylic acid ester copolymers, polyimides, and urethane acrylate resins are particularly preferred, and acrylic resins, fluorine-based resins, and urethane acrylate resins are particularly preferred because of their excellent heat resistance and moldability.

[0146] The substrate may be a foam substrate, such as a foam sheet made of a synthetic resin foam such as polyurethane foam, polyethylene foam, polyacrylate foam, etc. Among these, polyurethane foam and polyacrylate foam are preferred because they have an excellent balance of heat resistance, conformability to the adherend, and adhesive strength.

[0147] The thickness of the substrate is, for example, preferably 1 to 1000 μm, particularly preferably 10 to 800 μm, further preferably 25 to 600 μm, and particularly preferably 50 to 400 μm.

[0148] As the release sheet, for example, a sheet made of any of the various synthetic resins exemplified above as the base material, paper, cloth, nonwoven fabric, etc. that has been subjected to a release treatment can be used. As the release sheet, it is preferable to use a silicone-based release sheet.

[0149] 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.

[0150] The conditions for the aging treatment are a temperature of 0 to 80°C and a time period of usually 1 to 30 days, specifically, for example, 1 to 20 days at 23°C, preferably 2 to 14 days at 23°C, particularly preferably 3 to 7 days at 23°C, or 1 to 10 days at 40°C. If the aging treatment conditions are at a temperature higher than 80°C, the optical properties of the PSA sheet tend to become insufficient due to the thermal history, and production efficiency tends to decrease.

[0151] As for drying conditions, the drying temperature is preferably 60 to 140° C., particularly preferably 80 to 120° C., and the drying time is preferably 0.5 to 30 minutes, particularly preferably 1 to 5 minutes.

[0152] The thickness of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet and substrate-less double-sided pressure-sensitive adhesive sheet is preferably 1 to 500 μm, particularly preferably 3 to 200 μm, even more preferably 5 to 100 μm, and especially preferably 10 to 50 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, the uniformity of the coating film tends to decrease, resulting in poor appearance, or air bubbles tend to enter the coating film, resulting in insufficient optical properties.

[0153] The thickness of the adhesive layer is determined by subtracting the measured thickness of the constituent members other than the adhesive layer from the measured thickness of the entire adhesive sheet using a Mitutoyo ID-C112B.

[0154] The haze of this pressure-sensitive adhesive sheet is preferably 3% or less, more preferably 2.5% or less, and particularly preferably 2% or less. Having a haze of this value or less tends to result in excellent optical properties. The haze can be determined by pressurizing and pasting this pressure-sensitive adhesive sheet onto a polyethylene terephthalate (PET) film and alkali-free glass to prepare a test piece consisting of a PET film / adhesive layer / alkali-free glass plate, and measuring this using a HAZE MATER NDH2000 (manufactured by Nippon Denshoku Industries Co., Ltd.) in an environment of 23°C and 50% RH.

[0155] The molding stability of the pressure-sensitive adhesive sheet can be confirmed by its elongation. The elongation is preferably 100 to 2000%, more preferably 200 to 1500%, even more preferably 300 to 1400%, particularly preferably 400 to 1300%, and especially preferably 500 to 1200%. If the elongation is too low, the pressure-sensitive adhesive layer may not be able to conform to the molded article, resulting in insufficient molding stability. If the elongation is too high, the holding power and humidity / heat durability may be insufficient. The elongation can be determined by subjecting the pressure-sensitive adhesive sheet to a tensile test in accordance with JIS K 7127. For example, a substrate-less pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer thickness of 200 μm is cut into a size of 15 mm wide and 75 mm long, and the release films on both sides are peeled off to prepare a test piece. The test piece is subjected to a tensile test at 23°C and 50% RH using an autograph (Shimadzu Corporation, Autograph AG-X) at a width of 15 mm, a gripping distance of 25 mm, and a pulling speed of 10 mm / min, whereby the elastic modulus can be determined.

[0156] Furthermore, such a PSA sheet may be protected by providing a release sheet on the outer side of the PSA layer, if necessary. In a PSA sheet in which the PSA layer is formed on one side of a substrate, the PSA layer can be protected by applying a release treatment to the side of the substrate opposite the PSA layer, thereby utilizing the release-treated surface.

[0157] This adhesive can be used to bond various components, and because it has excellent adhesive strength, heat resistance, moist heat resistance, and optical properties, it is particularly used as a single-sided or double-sided adhesive sheet used for bonding or molding decorative films, and as a film for electronic components.

[0158] <Decorative Film> A decorative film according to one embodiment of the present invention (hereinafter sometimes referred to as "present decorative film 1") includes the present pressure-sensitive adhesive sheet. A decorative film according to another embodiment of the present invention (hereinafter sometimes referred to as "present decorative film 2") is a decorative film including a pressure-sensitive adhesive layer formed from a polyester pressure-sensitive adhesive composition containing a polyester resin (A) and a polyepoxy compound (B), wherein the polyester resin (A) satisfies all of the following (1) to (4): (1) The polyester resin (A) has structural units derived from polycarboxylic acids (a) and structural units derived from polyhydric alcohols (b). (2) The content of structural units derived from cyclic structure-containing polycarboxylic acids (a1) relative to 100 mol % of the structural units derived from polycarboxylic acids (a) is 30 mol % or more. (3) The structural units derived from polyhydric alcohols (b) include structural units derived from aliphatic polyhydric alcohols (b1). (4) The acid value of the polyester resin (A) is 1.5 to 30 mgKOH / g. The polyester resin (A) and polyepoxy compound (B) used in the present decorative film 2 are as described above in the present adhesive composition. The polyester adhesive composition used in the present decorative film 2 may also contain the polyisocyanate compound (C), carbodiimide compound, metal chelate compound, tackifier resin, antioxidant (D), and additives described above in the present adhesive composition. The present decorative films 1 and 2 (hereinafter sometimes simply referred to as "the present decorative films") will be described below.

[0159] The present decorative film is a film that imparts design to a resin layer formed from a thermoplastic resin or to a metal, and the present decorative film comprises at least a substrate and a pressure-sensitive adhesive layer.

[0160] The substrate in the present decorative film may be, for example, a resin layer formed from a thermoplastic resin. Examples of the thermoplastic resin include polyethylene terephthalate, acrylic resin, polycarbonate, acrylonitrile-butadiene-styrene copolymer, acrylonitrile-styrene-acrylic acid ester copolymer, polyimide acrylic resin, fluorine-based resin, and urethane acrylate resin. These may be used alone or in combination of two or more. Among these, acrylic resin, fluorine-based resin, and urethane acrylate resin are preferred because of their excellent ductility, bendability, and shape-following ability during molding.

[0161] The substrate of the decorative film may be colorless or colored. To color the substrate, a known colorant may be added to the resin. The substrate of the decorative film may be transparent, translucent, or opaque.

[0162] Generally, the thickness of the substrate is preferably 1 to 1000 μm, particularly preferably 10 to 800 μm, further preferably 25 to 600 μm, and particularly preferably 50 to 400 μm. When the thickness of the substrate is within the above range, the processability, shape conformability, and handleability tend to be good when producing a decorated molded product.

[0163] The decorative film may have a decorative layer on the substrate and / or between the substrate and the pressure-sensitive adhesive layer. The decorative layer is a layer provided to impart design to the decorative film, and is a pattern layer that expresses patterns, letters, patterned pictures, etc. The decorative layer can be provided, for example, by known printing methods such as inkjet printing, screen printing, and gravure printing, or by vapor deposition of metals or metal oxides such as aluminum, chromium, nickel, gold, tin, indium, and copper.

[0164] The substrate in this decorative film is located as the outermost layer of the decorated molded article after the molded article described below has been decorated with this decorative film, and serves as a protective layer for the decorated molded article. By forming the substrate using an acrylic resin or a urethane acrylate resin, a decorated molded article with excellent durability, such as abrasion resistance, chemical resistance, and weather resistance, can be obtained.

[0165] <Decorated Molded Body> A decorated molded body according to one embodiment of the present invention (hereinafter sometimes referred to as "the decorated molded body") is formed by laminating the decorative film onto a molded body by vacuum forming, pressure forming (preferably vacuum forming), etc. That is, the decorated molded body is formed by laminating the decorative film onto a molded body, and more specifically, by laminating an adhesive layer, and optionally a decorative layer, and a substrate onto the molded body.

[0166] The molded body may be, for example, a resin layer formed from a thermoplastic resin, such as polyethylene terephthalate, acrylic resin, polycarbonate, acrylonitrile-butadiene-styrene copolymer, or acrylonitrile-styrene-acrylic acid ester copolymer.

[0167] <Film for Electronic Components> A film for electronic components according to one embodiment of the present invention generally comprises the present pressure-sensitive adhesive sheet and a substrate.

[0168] The film for electronic components is used in the manufacturing process of electronic components, for example, in the semiconductor manufacturing process for masking, fixing, protecting components, transporting parts, and the like of electronic components.

[0169] Examples of the substrate in the film for electronic components include polyethylene terephthalate resin, polyimide resin, polyphenylene sulfide resin, polyethylene naphthalate resin, polyether ether ketone resin, polyether sulfone resin, polycyclohexane dimethylene terephthalate resin, polyetherimide resin, aromatic polyamide resin, and liquid crystal polymer resin. These may be used alone or in combination of two or more. Among these, polyethylene terephthalate resin, polyimide resin, and polyphenylene sulfide are preferred because of their excellent heat resistance and processability.

[0170] Generally, the thickness of the substrate is preferably 1 to 1000 μm, particularly preferably 3 to 500 μm, further preferably 5 to 300 μm, and particularly preferably 10 to 100 μm. If the thickness of the substrate is within the above range, the heat resistance and processability of the film for electromagnetic devices tend to be good.

[0171] 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 mass.

[0172] Further, the glass transition temperature (°C), acid value (mg KOH / g), the content (mol %) of structural units derived from cyclic structure-containing polycarboxylic acids (a1) relative to structural units derived from polycarboxylic acids (a), the content (mol %) of structural units derived from aliphatic polyhydric alcohols (b1) relative to structural units derived from polyhydric alcohols (b), the content (mass %) of structural units derived from dimer acids (a2) and / or structural units derived from dimer diols (b2) in the polyester resin (A), ester bond concentration (mmol / g), heat of crystalline fusion (J / g), peak top molecular weight (Mp), weight average molecular weight (Mw), and biomass content (%) were measured according to the description herein.

[0173] <Production of Polyester Resins (A) and (A')> The compositions shown in Table 1 below are the composition ratios of the finished products (resin composition ratios), and are the relative ratios (molar ratios) and mass % of the amounts of the constituent monomers of the resulting polyester resins (A) and (A').

[0174] [Production of polyester resin (A-1)] Thermometer, stirrer, rectification column, a reactor equipped with a nitrogen inlet tube, polycarboxylic acids (a) as isophthalic acid (IPA) 124 parts, terephthalic acid (TPA) 104.3 parts, trimellitic anhydride (TMAn) 4 parts, polyhydric alcohols as ethylene glycol (EG) 39 parts, dimer diol "Pripol 2033" (P2033) (manufactured by Croda) 664.2 parts, 2-methyl-1,3 propanediol (2MPG) 56.6 parts, tetrabutyl titanate 0.1 parts as a catalyst was charged, the internal temperature was raised to 260 ° C. over 2.5 hours, and an esterification reaction was carried out at 260 ° C. for 1.5 hours. Next, 0.1 parts of tetrabutyl titanate was added as a catalyst, the system was reduced in pressure to 2.5 hPa, and the polymerization reaction was carried out over 2 hours. The internal temperature was then lowered to 235° C., and 8 parts of trimellitic anhydride (TMAn) was added and depolymerization reaction was carried out over 1 hour to obtain a polyester resin (A-1).

[0175] [Production of Polyester Resins (A-2 to A-5, A'-2)] Polyester resins (A-2 to A-5, A'-2) were obtained in the same manner as A-1, except that the resin compositions were changed as shown in Table 1.

[0176] [Production of polyester resin (A'-1)] Thermometer, stirrer, rectification column, a reactor equipped with a nitrogen inlet tube, 225.5 parts of terephthalic acid (TPA) as polycarboxylic acids (a), 126.4 parts of ethylene glycol (EG) as polyhydric alcohols (b), dimer diol "Pripol 2033" (P2033) (manufactured by Croda) 646.4 parts, 1.8 parts of trimethylolpropane (TMP), 0.1 parts of tetrabutyl titanate as a catalyst was charged, the internal temperature was raised over 2.5 hours to 260 ° C., and an esterification reaction was carried out at 260 ° C. for 1.5 hours. Next, 0.1 parts of tetrabutyl titanate was added as a catalyst, the system was reduced in pressure to 2.5 hPa, and the polymerization reaction was carried out over 2 hours to obtain a polyester resin (A'-1).

[0177] The resin composition (structural units derived from components) of each polyester resin obtained is shown in Table 1 below, and various physical properties are shown in Table 2 below. In Table 1, the abbreviations are as follows. [Polycarboxylic acids (a)] [Cyclic structure-containing polycarboxylic acids (a1)] - "IPA": isophthalic acid - "TPA": terephthalic acid - "TMAn": trimellitic anhydride [Dimer acids (a2)] - "P1009": dimer acid "Pripol 1009" (manufactured by Croda) *Biomass-derived raw material [Aliphatic polycarboxylic acids] - "SebA": sebacic acid *Biomass-derived raw material [Polyhydric alcohols (b)] [Aliphatic polyhydric alcohols (b1)] - "EG": ethylene glycol *Biomass-derived raw material - "2MPG": 2-methyl-1,3 propanediol - "3MPG": 3-methyl-1,5 pentanediol - "TMP": trimethylolpropane [Dimer diols (b2)]・"P2033": Dimer diol "Pripol 2033" (manufactured by Croda) *Biomass-derived raw material

[0178]

[0179]

[0180] <PET resin sheet with one-sided release film> Each of the obtained polyester resins (A) and (A') was applied to a polyethylene terephthalate (PET) film (Lumirror T60, manufactured by Toray Industries, Inc., thickness 38 μm) so that the thickness after drying would be approximately 25 μm, and then dried at 100° C. for 3 minutes to form a pressure-sensitive adhesive layer. Thereafter, a release-treated PET film (release film) (SP-PET-01-BU, thickness 38 μm, manufactured by Mitsui Chemicals Tocello Inc.) was attached to the pressure-sensitive adhesive layer to protect its surface, and a PET resin sheet with one-sided release film was obtained.

[0181] <Crosslinking Agent> The following crosslinking agents were prepared: (B-1): N,N,N',N'-tetraglycidyl-m-xylylenediamine (manufactured by Mitsubishi Gas Chemical Company, Inc., "Tetrad X") (C-1): Trimer of isocyanurate of hexamethylene diisocyanate (manufactured by Tosoh Corporation, "Coronate HX")

[0182] <Acid Value Inhibitor> The following antioxidants were prepared: (D-1): Pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (manufactured by BASF Japan, hindered phenol-based antioxidant "Irganox 1010")

[0183] <Preparation of Polyester-Based Pressure-Sensitive Adhesive Compositions> Polyester-based pressure-sensitive adhesive compositions were prepared as follows using the polyester-based resins (A) and (A') and crosslinking agents obtained above.

[0184] Example 1 The polyester resin (A-1) obtained above was diluted with ethyl acetate to a solid content concentration of 50%, and 1.3 parts of a polyepoxy compound (B-1) (solid content) was blended with this polyester resin (A-1) solution (100 parts as solid content), followed by stirring and mixing, to obtain a polyester pressure-sensitive adhesive composition.

[0185] Examples 2 to 5, Comparative Examples 1 to 3 Polyester-based pressure-sensitive adhesive compositions were obtained in the same manner as in Example 1, except that the components shown in Table 3 were blended.

[0186] <PET Pressure-Sensitive Adhesive Sheet with Single-Sided Release Film> Each of the obtained polyester-based pressure-sensitive adhesive compositions was applied to a polyethylene terephthalate (PET) film (Lumirror T60, manufactured by Toray Industries, Inc., thickness 38 μm) so that the thickness after drying would be approximately 25 μm, and then dried at 100° C. for 3 minutes to form a pressure-sensitive adhesive layer. Thereafter, a release-treated PET film (release film) (SP-PET-01-BU, thickness 38 μm, manufactured by Mitsui Chemicals Tocello Inc.) was attached to the pressure-sensitive adhesive layer to protect its surface, and the layer was aged in an atmosphere at 40° C. for 4 days to obtain a PET pressure-sensitive adhesive sheet with a single-sided release film.

[0187] The resulting PET pressure-sensitive adhesive sheets with a single-sided release film were evaluated as follows. The evaluation results are shown in Table 3 below.

[0188] [Gel Fraction] The PET pressure-sensitive adhesive sheet with one-sided release film obtained above was cut into a size of 4 cm x 4 cm, and the release film was peeled off. This was wrapped in a 200-mesh SUS wire netting and immersed in toluene at 23°C for 24 hours. The mass of the insoluble pressure-sensitive adhesive component remaining in the wire netting relative to the mass of the pressure-sensitive adhesive component before immersion, minus the mass of the PET substrate, was measured, and the mass percentage was calculated according to the following formula, which was defined as the gel fraction (%). Gel fraction (%) = mass of insoluble pressure-sensitive adhesive component remaining in the wire netting after immersion / mass of pressure-sensitive adhesive component before immersion x 100

[0189] [Adhesive strength (peel strength) (against SUS-BA)] A SUS-BA plate was prepared as an adherend. The PET pressure-sensitive adhesive sheet with a release film on one side obtained above was cut to 25 mm x 200 mm in an environment of 23°C and 50% RH, and the release film was then peeled off. The pressure-sensitive adhesive layer side was then pressed and attached to the SUS-BA plate by rolling a 2 kg roller back and forth twice. After leaving the sheet to stand for 30 minutes in the same atmosphere, the 180-degree peel strength (N / 25 mm) was measured at a peel speed of 300 mm / min using an autograph (Shimadzu Corporation, Autograph AG-X 50N). (Evaluation criteria) ◎ (excellent): Adhesive strength of 5N / 25mm or more, with no adhesive residue on the adherend ○ (very good): Adhesive strength of 3N / 25mm or more and less than 5N / 25mm, with no adhesive residue on the adherend △ (good): Adhesive strength of 1N / 25mm or more and less than 3N / 25mm, with no adhesive residue on the adherend × (poor): Adhesive strength less than 1N, or adhesive residue on the adherend

[0190] [Adhesive Strength (Peel Strength) (Against ABS)] An ABS plate was prepared as an adherend. The PET pressure-sensitive adhesive sheet with one-sided release film obtained above was cut to 25 mm x 200 mm in an environment of 23°C and 50% RH, and the release film was then peeled off. The pressure-sensitive adhesive layer side was then pressed and attached to a SUS-BA plate using a 2 kg roller, which was rolled back and forth twice. After leaving the sheet to stand for 30 minutes in the same atmosphere, the 180° peel strength (N / 25 mm) was measured using an autograph (Shimadzu Corporation, Autograph AG-X 50N) at a peel speed of 300 mm / min. (Evaluation criteria) ◎ (excellent): Adhesive strength of 5N / 25mm or more, with no adhesive residue on the adherend ○ (very good): Adhesive strength of 3N / 25mm or more and less than 5N / 25mm, with no adhesive residue on the adherend △ (good): Adhesive strength of 1N / 25mm or more and less than 3N / 25mm, with no adhesive residue on the adherend × (poor): Adhesive strength less than 1N, or adhesive residue on the adherend

[0191] [Optical Properties (H1: Resin Sheet Haze)] The PET resin sheet with one-sided release film obtained above was cut into a size of 30 mm x 50 mm under an environment of 23 ° C. and 50% RH, and then the release film was peeled off. The pressure-sensitive adhesive layer side was pressed and attached to alkali-free glass (Corning Eagle XG) by rolling a 2 kg roller back and forth twice to prepare a test piece consisting of a PET film / polyester-based resin layer / alkali-free glass plate. The haze (H1) of the test piece under an environment of 23 ° C. and 50% RH was measured using a HAZE MATER NDH2000 (Nippon Denshoku Industries Co., Ltd.).

[0192] [Optical Properties (H2: Adhesive Sheet Haze)] The PET adhesive sheet with one-sided release film obtained above was cut to a size of 30 mm x 50 mm under an environment of 23 ° C. and 50% RH, and then the release film was peeled off. The adhesive layer side was pressure-attached to alkali-free glass (manufactured by Corning, Eagle XG) by rolling a 2 kg roller back and forth twice to prepare a test piece consisting of PET film / adhesive layer / alkali-free glass plate. The haze (H2) of the test piece under an environment of 23 ° C. and 50% RH was measured using a HAZE MATER NDH2000 (manufactured by Nippon Denshoku Industries Co., Ltd.).

[0193] [Optical Properties (ΔH)] The haze shift of a pressure-sensitive adhesive prepared by blending polyester resins (A) and (A') with a polyepoxy compound (B) or a polyisocyanate compound (C) was calculated using the following formula to evaluate the optical properties. Haze shift (ΔH) = Adhesive sheet haze (H2) - Resin sheet haze (H1) (Evaluation criteria) Excellent (excellent): Haze shift is 0.1 or less Good (very good): Haze shift is greater than 0.1 and less than 0.5 Good (good): Haze shift is greater than 0.5 and less than 1.0 Poor (poor): Haze shift is greater than 1.0

[0194] <PI Pressure-sensitive adhesive sheet with single-sided release film> Each of the obtained polyester-based pressure-sensitive adhesive compositions was applied to a polyimide (PI) film (Kapton 200H, 50 μm thick, manufactured by DuPont-Toray Co., Ltd.) so that the thickness after drying would be approximately 25 μm, and then dried at 100° C. for 3 minutes to form a pressure-sensitive adhesive layer. Thereafter, a release-treated PET film (release film) (SP-PET-01-BU, 38 μm thick, manufactured by Mitsui Chemicals Tocello Inc.) was attached to the pressure-sensitive adhesive layer to protect its surface, and the layer was aged in an atmosphere at 40° C. for 4 days to obtain a PI pressure-sensitive adhesive sheet with single-sided release film.

[0195] The resulting PI PSA sheets with a single-sided release film were evaluated as follows, and the evaluation results are shown in Table 3 below.

[0196] [Heat Resistance] The release film was peeled off from the PI pressure-sensitive adhesive sheet with a single-sided release film obtained above, and the sheet was laminated to copper foil in an environment of 23°C and 50% RH. The sheet was then cut to a size of 2.0 x 2.0 cm and heat-treated in an environment of 130°C for 1 hour to prepare a test piece consisting of copper foil / adhesive layer / PI. The test piece was floated with the PI film side facing up in a solder bath at a predetermined temperature (300°C, 320°C) for 60 seconds to measure heat resistance. (Evaluation Criteria) ⊚ (Excellent): No change in appearance × (Poor): Change in appearance such as lifting or peeling

[0197] [Heat and Moisture Resistance] A SUS-BA plate was prepared as an adherend. The PET pressure-sensitive adhesive sheet with a release film on one side obtained above was cut to 25 mm x 200 mm in an environment of 23°C and 50% RH, and the release film was then peeled off. The pressure-sensitive adhesive layer side was then pressed and attached to the SUS-BA plate by rolling a 2 kg roller back and forth twice. The sheet was then left to stand for 500 hours in an environment of 85°C and 85% RH, and then left for another hour in an environment of 23°C and 50% RH. After that, the 180-degree peel strength (N / 25 mm) was measured at a peel speed of 300 mm / min using an autograph (Shimadzu Corporation, Autograph AG-X 50N). (Evaluation criteria) ◎ (excellent): Adhesive strength of 10 N / 25 mm or more, with no adhesive residue on the adherend ○ (very good): Adhesive strength of 5 N / 25 mm or more, but less than 10 N / 25 mm, with no adhesive residue on the adherend △ (good): Adhesive strength of 3 N / 25 mm or more, but less than 5 N / 25 mm, with no adhesive residue on the adherend × (poor): Adhesive strength less than 3 N, or adhesive residue on the adherend

[0198]

[0199] The results in Table 3 show that, in the present invention, the polyester-based pressure-sensitive adhesive compositions and pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets of Examples 1 to 5 were excellent in adhesive strength, heat resistance, and moist heat resistance, and also in optical properties. In contrast, the pressure-sensitive adhesive compositions and pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets of Comparative Examples 1 to 3 were excellent in optical properties, but were poor in at least one of adhesive strength, heat resistance, and moist heat resistance, and did not satisfy the object of the present invention.

[0200] Although the above examples show specific embodiments of the present invention, the examples are merely illustrative and should not be construed as limiting. Various modifications that are obvious to those skilled in the art are all intended to fall within the scope of the present invention.

[0201] The polyester-based pressure-sensitive adhesive composition of the present invention has excellent adhesive strength, heat resistance, moist heat resistance, and optical properties when used as a pressure-sensitive adhesive, and such a polyester-based pressure-sensitive adhesive composition is particularly effective as a pressure-sensitive adhesive used in decorative films and films for electronic components.

Claims

1. A polyester-based pressure-sensitive adhesive composition containing a polyester-based resin (A) and a polyepoxy-based compound (B), wherein the polyester-based resin (A) satisfies all of the following (1) to (6). (1) The polyester-based resin (A) has structural units derived from polycarboxylic acids (a) and structural units derived from polyhydric alcohols (b). (2) The content of the structural units derived from cyclic-structure-containing polycarboxylic acids (a1) with respect to 100 mol% of the structural units derived from polycarboxylic acids (a) is 30 mol% or more. (3) The structural units derived from polyhydric alcohols (b) contain structural units derived from aliphatic polyhydric alcohols (b1). (4) The acid value of the polyester-based resin (A) is 1.5 to 30 mgKOH / g. (5) The glass transition temperature of the polyester-based resin (A) is -75 to -20°C. (6) The structural units derived from cyclic esters in the polyester-based resin (A) are less than 140 mol% with respect to 100 mol% of the structural units derived from polycarboxylic acids (a).

2. The polyester-based pressure-sensitive adhesive composition according to Claim 1, wherein the structural units derived from the cyclic-structure-containing polycarboxylic acids (a1) are structural units derived from monocyclic polycarboxylic acids (a1-1).

3. The polyester-based pressure-sensitive adhesive composition according to Claim 1 or 2, wherein the structural units derived from the aliphatic polyhydric alcohols (b1) contain structural units derived from polyhydric alcohols having a hydrocarbon group in at least one of the side chains.

4. The polyester-based pressure-sensitive adhesive composition according to Claim 1 or 2, wherein the polyester-based resin (A) has structural units derived from dimer acids (a2) and / or structural units derived from diol dimers (b2).

5. The polyester-based pressure-sensitive adhesive composition according to claim 1 or 2, wherein the content of the structural unit derived from the aliphatic polyhydric alcohol (b1) is 5 to 80 mol% with respect to 100 mol% of the structural unit derived from the polyhydric alcohol (b).

6. The polyester-based pressure-sensitive adhesive composition according to claim 1 or 2, wherein the structural unit derived from the polyhydric alcohol (b) contains a structural unit derived from dimer diols (b2).

7. The polyester-based pressure-sensitive adhesive composition according to claim 4, wherein the total content of the structural unit derived from the dimer acid (a2) and the structural unit derived from the dimer diol (b2) with respect to the entire polyester-based resin (A) is 20 to 90% by mass.

8. The polyester-based pressure-sensitive adhesive composition according to claim 1 or 2, wherein the ester bond concentration of the polyester-based resin (A) is 1.5 to 8.0 mmol / g.

9. The polyester-based pressure-sensitive adhesive composition according to claim 1 or 2, wherein the heat of crystal fusion of the polyester-based resin (A) is 3 J / g or less.

10. The polyester-based pressure-sensitive adhesive composition according to claim 1 or 2, wherein the polyepoxy compound (B) contains a nitrogen atom-containing polyepoxy compound.

11. The polyester-based pressure-sensitive adhesive composition according to claim 1 or 2, wherein the equivalent of the epoxy group of the polyepoxy compound (B) with respect to the carboxyl group of the polyester-based resin (A) is 0.3 to 5 equivalents.

12. The polyester-based pressure-sensitive adhesive composition according to claim 1 or 2, wherein the content of the polyepoxy compound (B) is 0.1 to 15 parts by mass with respect to 100 parts by mass of the polyester-based resin (A).

13. A polyester-based pressure-sensitive adhesive obtained by crosslinking the polyester-based pressure-sensitive adhesive composition according to claim 1 or 2.

14. The polyester-based pressure-sensitive adhesive according to claim 13, wherein the gel fraction is 20 to 100%.

15. An adhesive sheet having an adhesive layer containing the polyester-based pressure-sensitive adhesive according to claim 13.

16. The adhesive sheet according to claim 15, wherein the haze is 3% or less.

17. An adhesive sheet having a base material and an adhesive layer containing the polyester-based pressure-sensitive adhesive according to claim 13, wherein the adhesive layer is provided on at least one side of the base material.

18. A decorative film including the adhesive sheet according to claim 17.

19. A film for electronic components comprising the adhesive sheet according to claim 17.

20. A decorated molded article in which the decorative film according to claim 18 is laminated on a molded article.

21. A decorative film including an adhesive layer formed from a polyester-based pressure-sensitive adhesive composition containing a polyester-based resin (A) and a polyepoxy-based compound (B), wherein the polyester-based resin (A) satisfies all of the following (1) to (4). (1) The polyester-based resin (A) has a structural unit derived from polycarboxylic acids (a) and a structural unit derived from polyhydric alcohols (b). (2) The content of the structural unit derived from cyclic structure-containing polycarboxylic acids (a1) with respect to 100 mol% of the structural unit derived from polycarboxylic acids (a) is 30 mol% or more. (3) The structural unit derived from polyhydric alcohols (b) contains a structural unit derived from aliphatic polyhydric alcohols (b1). (4) The acid value of the polyester-based resin (A) is 1.5 to 30 mgKOH / g.