Polyester resin composition, pressure-sensitive adhesive composition, pressure-sensitive adhesive, pressure-sensitive adhesive sheet, and double-sided pressure-sensitive adhesive sheet

Abstract

To provide a polyester-based resin composition which uses a raw material derived from a plant friendly to the global environment, has good adhesive physical properties to various adherends, and is excellent in adhesive physical properties such as an adhesive force and a holding force.SOLUTION: A polyester-based resin composition contains a polyester-based resin (A), in which the polyester-based resin (A) contains a structural unit derived from at least one compound (a1) of dimer acids and dimer diol, and a structural unit derived from an aromatic compound (a2), and a ratio (X1 / X2) of molar concentration (X1) of the structural unit derived from the compound (a1) to molar concentration (X2) of the structural unit derived from the aromatic compound (a2) is larger than 2.0.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a polyester resin composition, an adhesive composition containing the polyester resin composition, an adhesive, an adhesive sheet, and a double-sided adhesive sheet. More specifically, the present invention relates to a polyester resin composition using a plant-derived raw material that is friendly to the global environment, and when used as an adhesive, a polyester resin composition excellent in adhesive physical properties such as adhesive strength and holding power, an adhesive composition containing the polyester resin composition, an adhesive, an adhesive sheet, and a double-sided adhesive sheet.

Background Art

[0002] In recent years, from the viewpoints of miniaturization and weight reduction of products, adhesives have been used for joining components and the like. As such an adhesive, an adhesive using a polyester resin having excellent adhesive strength has been studied as an alternative to generally used acrylic resins.

[0003] On the other hand, recently, as part of measures to address the depletion of fossil resources and global warming, the use of plant-derived raw materials, which are renewable resources, has been recommended, and there is a demand for adhesives with a high degree of biomass using plant-derived raw materials that are friendly to the global environment.

[0004] As such a polyester-based adhesive using a plant-derived raw material, for example, in Patent Document 1, an adhesive containing a polyester resin polymerized using 90 to 50 mol% of an aromatic dicarboxylic acid and 10 to 50 mol% of a dimer acid as a dicarboxylic acid component and a glycol having 4 or more carbon atoms having an alkyl group in the side chain of 30 mol% or more as a glycol component has been proposed to be excellent in heat resistance and durability. In Patent Document 2, a polyester obtained by polymerizing using dimer acid as a dicarboxylic acid component and dimer diol as a diol component, and having 1.04 to 2.10 moles of hydroxyl group contained in the diol component per 1 mole of carboxyl group contained in the dicarboxylic acid component, and an adhesive containing a tackifier have been proposed, which use a small amount of organic solvent, enable thick coating, and are excellent in adhesiveness, retention, and anti-repulsion properties.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the disclosed technology of Patent Document 1, although plant-derived dimer acid is used, since a large amount of petroleum-derived aromatic dicarboxylic acid is used, the problem of high environmental load remains. Further, in the disclosed technology of Patent Document 2 above, although the environmental load is reduced because plant-derived raw materials are mainly used, since the resin is too soft, the elastic modulus when used as an adhesive sheet becomes too low, so the adhesive physical properties such as adhesive strength when used as a double-sided adhesive tape tend to be inferior, and it was not yet satisfactory. Although the adhesive physical properties including adhesive strength can be improved by adding a tackifier or the like, the problem was that the degree of freedom in design decreased because the number of essential components increased.

[0007] Generally, when using a polyester resin composition as an adhesive, crosslinking agents such as isocyanate compounds, epoxy compounds, and metal chelate compounds, and additives such as tackifiers are often used. However, when producing a polyester resin composition using plant-derived raw materials that are friendly to the global environment, such as dimer acids and dimer diols with long alkyl chains, the polarity becomes extremely low, and thus the compatibility with the above additives tends to decrease. Therefore, when the above additives are used in a polyester resin composition using dimer acids and dimer diols with long alkyl chains, there is a problem that the compatibility is low and the adhesive physical properties deteriorate.

[0008] Therefore, in the present invention, under such circumstances, even in a polyester resin composition using recycled materials that are friendly to the global environment, such as plant-derived raw materials and recycled polyethylene terephthalate (PET), etc., when used as an adhesive, it has good adhesive physical properties to various adherends, and an object of the present invention is to provide a polyester resin composition excellent in adhesive physical properties such as adhesive strength and holding power, an adhesive composition containing the same, an adhesive, an adhesive sheet, and a double-sided adhesive sheet.

Means for Solving the Problems

[0009] However, the present inventors have found that in a polyester resin composition, as polycarboxylic acids and polyols constituting the polyester resin, it contains at least one compound of dimer acids and dimer diols, and an aromatic compound, and by making the ratio of the molar concentration of the structural unit derived from at least one compound of dimer acids and dimer diols to the molar concentration of the structural unit derived from the aromatic compound in the polyester resin greater than 2.0, it is possible to obtain an adhesive that is friendly to the global environment, has good adhesive physical properties to various adherends, and is excellent in adhesive strength and holding power, thereby completing the present invention.

[0010] That is, the present invention relates to a polyester resin composition containing a polyester resin (A), wherein the polyester resin (A) contains a structural unit derived from at least one compound (a1) of dimer acids and dimer diols, and a structural unit derived from an aromatic compound (a2), and the ratio (X1 / X2) of the molar concentration (X1) of the structural unit derived from the compound (a1) to the molar concentration (X2) of the structural unit derived from the aromatic compound (a2) is greater than 2.0. This is the first gist of the polyester resin composition.

[0011] Further, in the present invention, an adhesive composition containing the above polyester resin composition is the second gist, an adhesive obtained by crosslinking the adhesive composition is the third gist, an adhesive sheet having an adhesive layer containing the above adhesive is the fourth gist, and a double-sided adhesive sheet having an adhesive layer containing the above adhesive is the fifth gist.

Effects of the Invention

[0012] The polyester resin composition of the present invention contains a polyester resin (A), wherein the polyester resin (A) contains a structural unit derived from at least one compound (a1) of dimer acids and dimer diols, and a structural unit derived from an aromatic compound (a2), and the ratio (X1 / X2) of the molar concentration (X1) of the structural unit derived from the compound (a1) to the molar concentration (X2) of the structural unit derived from the aromatic compound (a2) in the above polyester resin (A) is greater than 2.0. Therefore, it is a polyester resin composition with a high biomass content and friendly to the global environment, and has excellent effects on adhesive force and holding power when used as an adhesive. Therefore, it can be effectively used for single-sided or double-sided adhesive sheets used for bonding optical members, single-sided or double-sided adhesive sheets for fixing members of portable electronic devices, and fixing electronic components.

Modes for Carrying Out the Invention

[0013] Hereinafter, the configuration of the present invention will be described in detail, but these show an example of a desirable embodiment. In the present invention, the term "carboxylic acids" includes carboxylic acid derivatives such as carboxylates, carboxylic anhydrides, carboxylic acid halides, and carboxylic acid esters in addition to carboxylic acids.

[0014] The polyester resin composition of the present invention contains a structural unit derived from at least one compound (a1) of dimer acids and dimer diols, and a structural unit derived from an aromatic compound (a2), and the ratio (X1 / X2) of the molar concentration (X1) of the structural unit derived from the compound (a1) to the molar concentration (X2) of the structural unit derived from the aromatic compound (a2) is greater than 2.0 and contains a polyester resin (A). Hereinafter, the polyester resin (A) will be described in detail.

[0015] <Polyester resin (A)> A polyester resin has, as its resin structure, a structural unit derived from polycarboxylic acids and a structural unit derived from polyols, and is usually obtained by polymerizing a polymerization component containing polycarboxylic acids and polyols.

[0016] The polyester resin (A) used in the present invention contains a structural unit derived from at least one compound (a1) of dimer acids which are polycarboxylic acids and dimer diols which are polyols, and a structural unit derived from an aromatic compound (a2), and is particularly obtained by polymerizing a polymerization component containing at least one compound (a1) of dimer acids and dimer diols and an aromatic compound (a2).

[0017] [At least one compound (a1) of dimer acids and dimer diols] The above-mentioned at least one compound (a1) of dimer acids and dimer diols (hereinafter sometimes referred to as "compound (a1)") is at least one of dimer acid which is a polycarboxylic acid and dimer diol which is a polyol as described above.

[0018] The above dimer acids are mainly composed of unsaturated fatty acid dimers with an average carbon number of 10 to 26, preferably unsaturated fatty acid dimers with an average carbon number of 12 to 24, and more preferably unsaturated fatty acid dimers with an average carbon number of 14 to 22. Specifically, for example, they are dicarboxylic acids derived from unsaturated fatty acids such as oleic acids, linoleic acids, linolenic acids, and erucic acids. Here, the "main component" refers to a component whose content is 90% by weight or more, preferably 95% by weight or more, and more preferably 98% by weight or more of the whole.

[0019] Examples of the dimer acids used in the present invention include dimer acids derived from the above unsaturated fatty acids (with carbon numbers 36 and 44 being the main ones), hydrogenated products of the above dimer acids, etc. Among them, hydrogenated products of dimer acids are preferred in terms of being less likely to form crystals.

[0020] As raw materials for the above dimer acids, usually plants, beef tallow, etc. are used. In the present invention, dimer acids derived from any raw materials can be used, but it is preferable to use plant-derived raw materials that are friendly to the global environment. By using plant-derived raw materials, the biomass degree of the polyester resin (A) described later can be increased.

[0021] When using the above dimer acids as a copolymer component of the polyester resin (A), the content is preferably 10 to 100 mol% based on the total amount of polycarboxylic acids, particularly preferably 20 to 99 mol%, more preferably 35 to 90 mol%, and especially preferably 51 to 80 mol%. If such a content is too small, it tends to become too hard and the adhesive strength decreases. In addition, if such a content is too large, it tends to become too soft and the adhesive properties slightly decrease.

[0022] The dimerdiol used in the present invention is generally a diol derived from the above dimer acids. In the present invention, the above dimerdiol is preferably a plant-derived raw material, like the dimer acids.

[0023] When using the above dimer diol as a copolymer component of the polyester resin (A), the content is preferably 10 to 100 mol%, particularly preferably 20 to 99 mol%, more preferably 35 to 90 mol%, and especially preferably 51 to 80 mol% based on the total polyol. If the content is too low, the adhesion properties tend to decrease. If the content is too high, it becomes too soft and the adhesion properties tend to decrease slightly.

[0024] [Aromatic compound (a2)] Examples of the aromatic compound (a2) include aromatic polyvalent carboxylic acids and aromatic polyols. Among them, it is preferable to use aromatic polyvalent carboxylic acids as the aromatic compound (a2) from the viewpoint of excellent adhesive strength and holding power.

[0025] (Aromatic polyvalent carboxylic acids) Examples of the aromatic polyvalent carboxylic acids include divalent aromatic dicarboxylic acids and trivalent or higher aromatic polyvalent carboxylic acids. Aromatic dicarboxylic acids are preferably used from the viewpoint of stably obtaining the polyester resin (A).

[0026] Examples of the aromatic dicarboxylic acids include benzene-based aromatic dicarboxylic acids such as phthalic acids, terephthalic acids, isophthalic acids, benzylmalonic acids, diphenic acids, 4,4'-oxydibenzoic acids, 1,8-naphthalenedicarboxylic acids, 2,3-naphthalenedicarboxylic acids, 2,7-naphthalenedicarboxylic acids, etc.; heterocyclic dicarboxylic acids such as furandicarboxylic acids, thiophenedicarboxylic acids (pyrrole, pyrazole, imidazole, pyridine, pyridazine, pyrimidine, pyrazine, etc.). These may be used alone or in combination of two or more. Among them, terephthalic acids, isophthalic acids, and furandicarboxylic acids are preferable from the viewpoint of easy availability.

[0027] Examples of the above trivalent or higher aromatic polycarboxylic acids include trimellitic acids, pyromellitic acids, trimesic acids, etc. These may be used alone or in combination of two or more.

[0028] Also, it is preferable to use polyethylene terephthalate as the above aromatic polycarboxylic acids. The above polyethylene terephthalate is a polyester resin obtained by polymerizing terephthalic acids and ethylene glycol. By using the above polyethylene terephthalate, the polyester resin (A) has, as a structural unit derived from the aromatic compound (a2), a structural unit derived from terephthalic acids derived from polyethylene terephthalate. The above polyethylene terephthalate may, if necessary, be modified with substances such as isophthalic acids, phthalic anhydrides, adipic acids, cyclohexanedicarboxylic acids, sebacic acids, 1,3 - butanediol, 1,4 - butanediol, cyclohexanedimethanol. Also, the above polyethylene terephthalate may be a virgin product or a recycled product, but it is preferable to use a recycled product from the viewpoint of the global environment.

[0029] When using the above aromatic polycarboxylic acids as a copolymer component of the polyester resin (A), the content is preferably 1 mol% or more and less than 50 mol%, more preferably 5 - 47 mol%, still more preferably 10 - 43 mol%, particularly preferably 15 - 40 mol%, and even more preferably 20 - 36 mol% with respect to the total amount of polycarboxylic acids. If such a content is too small, the cohesive force decreases, resulting in a decrease in adhesive force and a tendency that sufficient adhesive performance cannot be obtained. If it is too large, the initial adhesive force (tack) tends to decrease.

[0030] (Aromatic polyol) Examples of the above aromatic polyol include divalent aromatic diols. Examples of the above-mentioned divalent aromatic diols include bisphenol A, 4,4'-thiodiphenol, 4,4'-methylenediphenol, 4,4'-dihydroxybiphenyl, o-, m-, and p-dihydroxybenzene, 2,5-naphthalenediol, p-xylenediol, and their ethylene oxide adducts, propylene oxide adducts, etc. These may be used alone or in combination of two or more.

[0031] When using the above aromatic polyol as a copolymer component of the polyester resin (A), the content is preferably 1 to 50 mol%, more preferably 5 to 40 mol%, and still more preferably 10 to 30 mol% based on the total polyol. If the content is too low, the cohesive force tends to decrease and the adhesive force tends to decrease. If it is too high, the initial adhesive force tends to decrease.

[0032] In addition to the above compounds (a1) and aromatic compounds (a2), the polyester resin (A) used in the present invention may use an aliphatic compound (a3) as a copolymer component.

[0033] [Aliphatic compound (a3)] Examples of the above aliphatic compounds include aliphatic polycarboxylic acids and aliphatic polyols.

[0034] (Aliphatic polycarboxylic acids) Examples of the above aliphatic polycarboxylic acids include divalent aliphatic dicarboxylic acids and polycarboxylic acids having three or more valences. Examples of the above aliphatic dicarboxylic acids include linear alkyl dicarboxylic acids such as malonic acids, dimethylmalonic acids, succinic acids, glutaric acids, adipic acids, trimethyladipic acids, pimelic acids, 2,2-dimethylglutaric acids, azelaic acids, sebacic acids, 1,9-nonanedicarboxylic acids, decanedicarboxylic acids, etc.; acyclic aliphatic dicarboxylic acids such as fumaric acids, maleic acids, itaconic acids, thiodipropionic acids, diglycolic acids, etc. Examples of the cyclic aliphatic dicarboxylic acids include 1,3 - cyclopentanedicarboxylic acids, 1,2 - cyclohexanedicarboxylic acids, 1,3 - cyclohexanedicarboxylic acids, 1,4 - cyclohexanedicarboxylic acids, 2,5 - norbornanedicarboxylic acids, adamantanedicarboxylic acids, and the like. Examples of the polyvalent carboxylic acids having three or more valences include, for example, adamantanetricarboxylic acids and the like. These aliphatic polyvalent carboxylic acids may be used alone or in combination of two or more.

[0035] From the viewpoint of improving the initial adhesiveness (tack), it is preferable that the aliphatic polyvalent carboxylic acids contain acyclic aliphatic dicarboxylic acids having 4 or more carbon atoms (including the carbon atoms of the carboxy group), and among them, it is more preferable to contain acyclic aliphatic dicarboxylic acids having 9 to 12 carbon atoms (including the carbon atoms of the carboxy group) such as azelaic acids and sebacic acids.

[0036] The content of such acyclic aliphatic dicarboxylic acids having 4 or more carbon atoms is preferably 95 mol% or less, more preferably 5 to 90 mol%, and particularly preferably 10 to 70 mol% with respect to the total polyvalent carboxylic acids. If such a content ratio is too high, the adhesiveness tends to decrease or the resin may crystallize and sufficient adhesive performance may not be obtained.

[0037] In addition, in order to increase the biomass content, it is preferable to use plant - derived aliphatic polyvalent carboxylic acids as the aliphatic polyvalent carboxylic acids. Examples of the plant - derived aliphatic polyvalent carboxylic acids include, for example, sebacic acids derived from castor oil, succinic acids derived from corn, and the like.

[0038] (Aliphatic polyol) Examples of the aliphatic polyol include divalent aliphatic diols and trivalent or higher aliphatic polyhydric alcohols. Examples of the above-mentioned divalent aliphatic diols include acyclic aliphatic diols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 2,4-dimethyl-2-ethylhexane-1,3-diol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,6-hexanediol; and cyclic aliphatic diols such as 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, spiroglycol, tricyclodecanedimethanol, adamantanediol, isosorbide, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, etc. Examples of the above-mentioned trivalent or higher aliphatic polyhydric alcohols include pentaerythritol, dipentaerythritol, tripentaerythritol, glycerin, trimethylolpropane, trimethylolethane, 1,2,4-butanetriol, 1,2,5-pentanetriol, 1,3,6-hexanetriol, adamantanetriol, etc. These aliphatic polyols may be used alone or in combination of two or more.

[0039] Among these, from the viewpoint of lowering the glass transition temperature (Tg) of the polyester resin (A) and improving the initial adhesiveness, it is preferable to contain an acyclic aliphatic diol in the polyol. More preferably, it is an acyclic aliphatic diol having 2 to 20 carbon atoms. Particularly preferably, it is ethylene glycol, diethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, or 1,6-hexanediol. Among them, ethylene glycol is particularly preferable in that it can lower the glass transition temperature (Tg) of the polyester resin (A) and is more excellent in adhesiveness.

[0040] The content of the acyclic aliphatic diol is preferably 10 to 100 mol% based on the total polyol, more preferably 20 to 99 mol%, still more preferably 30 to 95 mol%, and particularly preferably 40 to 90 mol%. If such a content is too small, it tends to be difficult to obtain stable resin formation.

[0041] In order to increase the biomass content, it is preferable to use a plant-derived polyol as the aliphatic polyol. Examples of the plant-derived polyol include isosorbide, fatty acid ester-based diols derived from castor oil, bioethylene glycol, bio-1,3-propanediol, biobutylene glycol, and the like. Among them, bioethylene glycol is preferable.

[0042] Further, polyethylene terephthalate may be used as the acyclic aliphatic diol. As described above, polyethylene terephthalate is a polyester resin obtained by polymerizing terephthalic acids and ethylene glycol. Therefore, by using polyethylene terephthalate, the polyester resin (A) will have a structural unit derived from ethylene glycol derived from polyethylene terephthalate as a structural unit derived from the acyclic aliphatic diol. Also, the above polyethylene terephthalate may be a virgin product or a recycled product, but it is preferable to use a recycled product from the viewpoint of the global environment.

[0043] Furthermore, from the viewpoint of forming reaction points with the polyisocyanate compound (B) described later in the polyester resin (A) and enhancing the cohesive force, it is preferable to use an aliphatic polyol having three or more hydroxyl groups as the aliphatic polyol. For example, trimethylolpropane, trimethylolethane, glycerin, pentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, 1,2,6-hexanetriol can be used. Among these, it is particularly preferable to use trimethylolpropane because gel is less likely to occur.

[0044] The content of such an aliphatic polyol having three or more hydroxyl groups is preferably 20 mol% or less, more preferably 0.1 to 10 mol%, and particularly preferably 0.5 to 5 mol% with respect to the total polyol. If the content of such an aliphatic polyol having three or more hydroxyl groups is too high, the production of the polyester resin (A) tends to be difficult.

[0045] Also, as described above, it is preferable to use a plant-derived aliphatic polyol. However, when the biomass degree of polycarboxylic acids is high, an aliphatic polyol not derived from plants may be used from the viewpoint of ease of polycondensation. However, even in that case, in order to increase the biomass degree, it is preferable to use an acyclic aliphatic diol having a linear structure with 4 or less carbon atoms, and particularly preferably an acyclic aliphatic diol having a linear structure with 2 to 3 carbon atoms. Examples of the acyclic aliphatic diol having a linear structure with 4 or less carbon atoms include ethylene glycol, 1,3-propanediol, 1,4-butanediol, etc. That is, when an aliphatic polyol having a small number of carbon atoms of 4 or less is used, the weight ratio of carboxylic acids having a high biomass degree as the polyester resin (A) increases, and the biomass degree can be increased.

[0046] [Production of Polyester Resin (A)] In the present invention, the polyester resin (A) can be produced by subjecting polycarboxylic acids and polyols to a polycondensation reaction in the presence of a catalyst by a known method. In the polycondensation reaction, first, an esterification reaction or a transesterification reaction is carried out, and then the polycondensation reaction is carried out. When it is not necessary to obtain a high molecular weight, it may be produced only by an esterification reaction or a transesterification reaction. When using the aforementioned polyethylene terephthalate, polyethylene terephthalate may be blended together with polycarboxylic acids and polyols.

[0047] In such an esterification reaction or transesterification reaction, a catalyst is used. Specifically, for example, titanium-based catalysts such as tetraisopropyl titanate and tetrabutyl titanate, antimony-based catalysts such as antimony trioxide, germanium-based catalysts such as germanium dioxide, and catalysts such as zinc acetate, manganese acetate, and dibutyltin oxide can be mentioned. One or more of these are used. Among these, antimony trioxide, tetrabutyl titanate, germanium dioxide, and zinc acetate are preferable in view of the balance between high catalytic activity and the hue of the resulting reaction product.

[0048] The blending amount of the above catalyst is preferably 1 to 10000 ppm, particularly preferably 10 to 5000 ppm, and more preferably 20 to 3000 ppm based on the total copolymerization components (by weight). If such a blending amount is too small, the polymerization reaction tends not to proceed sufficiently. If it is too large, there is no advantage such as shortening of the reaction time, and side reactions tend to occur easily.

[0049] Regarding the reaction temperature during the esterification reaction, 200 to 300 °C is preferable, particularly preferably 210 to 280 °C, and more preferably 220 to 260 °C. If such a reaction temperature is too low, the reaction tends not to proceed sufficiently. If it is too high, side reactions such as decomposition tend to occur easily. Also, the pressure during the reaction is usually normal pressure.

[0050] As the reaction conditions for the polycondensation reaction that is carried out after the above esterification reaction or transesterification reaction, a catalyst similar to that used in the above esterification reaction or transesterification reaction is further blended in a similar amount, and the reaction temperature is preferably 200 to 280°C, particularly preferably 210 to 270°C. It is preferable to gradually reduce the pressure of the reaction system and finally react at 5 hPa or less. If such a reaction temperature is too low, the reaction tends not to proceed sufficiently, and if it is too high, side reactions such as decomposition tend to occur easily.

[0051] Thus, a polyester resin (A) containing a structural unit derived from the compound (a1) and a structural unit derived from the aromatic compound (a2) is obtained.

[0052] In the present invention, from the viewpoint of excellent adhesive strength and holding power, the ratio (X1 / X2) of the molar concentration (X1) of the structural unit derived from the compound (a1) to the molar concentration (X2) of the structural unit derived from the aromatic compound (a2) in the above polyester resin (A) needs to be greater than 2.0. Preferably it is 2.2 or more, more preferably 2.3 or more, still more preferably 2.5 or more, and particularly preferably 3.0 or more. When (X1 / X2) is 2.0 or less, the adhesive strength and holding power decrease. Also, the upper limit value of (X1 / X2) is usually 20, preferably 10, more preferably 6.0, still more preferably 5.0, particularly preferably 4.0, and especially preferably 3.5. When the above compound (a1) contains an aromatic ring, it is included in the compound (a1) and not included in the aromatic compound (a2).

[0053] Also, when the above polyester resin (A) contains a structural unit derived from an aliphatic polyol (a3), from the viewpoint of the initial adhesive strength when used as an adhesive, the content ratio of the acyclic aliphatic diol having 2 to 20 carbon atoms among the structural units derived from the aliphatic polyol (a3) is preferably 10 mol% or more, more preferably 30 mol% or more, and particularly preferably 50 mol% or more.

[0054] The number average molecular weight of the polyester resin (A) used in the present invention is preferably 3,000 or more, more preferably 3,500 to 50,000, still more preferably 4,000 to 40,000, particularly preferably 5,000 to 30,000, especially preferably 6,000 to 20,000, and most preferably 7,000 to 15,000. If the number average molecular weight is too large, the handleability decreases, so a large amount of solvent is required, and the environmental load tends to increase. If the number average molecular weight is too small, the adhesive physical properties tend to decrease.

[0055] The weight average molecular weight of the polyester resin (A) is preferably 10,000 or more, more preferably 10,000 to 500,000, still more preferably 20,000 to 300,000, particularly preferably 30,000 to 250,000, especially preferably 40,000 to 200,000, and most preferably 50,000 to 150,000. If the weight average molecular weight is too small, the adhesive physical properties tend to decrease. If the weight average molecular weight is too large, the handleability decreases, so a large amount of solvent is required, and the environmental load tends to increase.

[0056] The above number average molecular weight and weight average molecular weight are the number average molecular weight and weight average molecular weight in terms of standard polystyrene molecular weight, and are measured by using two columns of TSKgel SuperMultipore HZ-M (exclusion limit molecular weight: 2×10 6 , theoretical plate number: 16,000 plates / book, filler material: styrene-divinylbenzene copolymer, filler particle size: 4 μm) in series on a high performance liquid chromatograph (manufactured by Tosoh Corporation, "HLC-8320GPC").

[0057] In addition, the biomass content of the polyester resin (A) is usually 50% or more, preferably 60% or more, more preferably 70% or more, particularly preferably 80% or more, especially preferably 85% or more, and most preferably 90% or more. The upper limit is 100%. If such a biomass content is low, the reduction of the environmental load tends to be insufficient.

[0058] Here, the biomass content of the polyester resin (A) refers to the weight ratio of the part of the plant-derived raw material used in the production of the polyester resin (A) incorporated into the resin with respect to the total weight of the polyester resin (A), and the calculation method is as follows. Regarding the biomass content of polycarboxylic acids and polyols, it is determined from the weighted average of their respective biomass contents. Also, among the following calculation methods, it is sufficient if the value obtained by any of the methods is within the above range.

[0059] (Calculation method) <When accompanied by a polycondensation reaction> Biomass content (%) = [(Number of moles of carbon of plant-derived monomers calculated from the molar ratio of polycarboxylic acids and polyols in the polyester resin (A)) / (Number of moles of carbon of all constituent monomers in the polyester resin (A))] × 100

[0060] <When not accompanied by a polycondensation reaction> Biomass content (%) = [(Number of moles of carbon of plant-derived monomers in the polyester resin (A)) / (Number of moles of carbon of all constituent monomers in the polyester resin (A))] × 100

[0061] Also, the above biomass content can be determined by analyzing the composition ratio by NMR and calculating the number of carbon atoms of the plant-derived monomers / the total number of carbon atoms.

[0062] Furthermore, the above biomass content can also be measured by the method described in "Discrimination Technology of the Origin of Biofuels Using Natural Radioactive Carbon C-14", Research Report No. 4, 2009, Tokyo Metropolitan Institute of Industrial Technology.

[0063] As a method for adjusting the above biomass content to a predetermined range, using plant-derived polycarboxylic acids or plant-derived polyols as the main component can be mentioned. In terms of being able to efficiently increase the biomass content, it is particularly preferable that the polycarboxylic acids are plant-derived.

[0064] In the present invention, it is preferable from the viewpoint of reducing environmental impact that the recycled carbon usage rate of the polyester resin (A) is 50% or more, more preferably 60% or more, still more preferably 70% or more, particularly preferably 80% or more, especially preferably 85% or more, and most preferably 90% or more. The upper limit is 100%. Here, the recycled carbon usage rate of the polyester resin (A) refers to the weight ratio of the raw materials containing recycled carbon used when producing the polyester resin (A) to the total weight of the polyester resin (A). Examples of the raw materials containing recycled carbon include plant-derived raw materials and recycled polyethylene terephthalate (recycled PET).

[0065] The calculation method of the recycled carbon usage rate can be calculated by the same method as the calculation method of the biomass content described above. That is, it is as follows. (Calculation method) (When accompanied by a polycondensation reaction) Recycled carbon usage rate (%) = [(Number of moles of recycled carbon calculated from the molar ratio of polycarboxylic acids and polyols in the polyester resin (A)) / (Number of moles of carbon of all constituent monomers in the polyester resin (A))] × 100

[0066] (When not accompanied by a polycondensation reaction) Recycled carbon usage rate (%) = [(Number of moles of recycled carbon in the polyester resin (A)) / (Number of moles of carbon of all constituent monomers in the polyester resin (A))] × 100

[0067] The glass transition temperature (Tg) of the polyester resin (A) is preferably -90 to 20°C, particularly preferably -60 to 0°C, and still more preferably -50 to -20°C. If the glass transition temperature (Tg) is too high, the adhesion when used as an adhesive tends to decrease, and if it is too low, the heat resistance and cohesive force tend to decrease.

[0068] The above glass transition temperature (Tg) is measured using a differential scanning calorimeter DSC Q20 manufactured by TA Instruments. The measurement temperature range is -90 to 100 °C, and the temperature increase rate is 10 °C / min.

[0069] The ester group concentration of the polyester resin (A) is usually 2 mmol / g or more, preferably 3 to 10 mmol / g, more preferably 3.6 to 6 mmol / g, and particularly preferably 4.2 to 5 mmol / g. If such an ester group concentration is too small, the polyester resin (A) becomes soft and the adhesive properties tend to deteriorate.

[0070] The above ester group concentration (mmol / g) refers to the number of moles of ester bonds in 1 g of the polyester resin (A), and is obtained, for example, as a calculated value from the charged amounts. Such a calculation method is a value obtained by dividing the number of moles of the smaller of the charged amounts of carboxylic acids and polyols by the total weight, and an example of the calculation formula is shown below. When the charged amounts of polycarboxylic acids and polyols are the same in molar amount, either of the following calculation formulas may be used. In addition, when using a monomer having both a carboxy group and a hydroxyl group, or when producing a polyester from caprolactone or the like, the calculation method will be changed as appropriate.

[0071] <When there is less polycarboxylic acid> Ester group concentration (mmol / g) = [((A1 / a1 × m1 + A2 / a2 × m2 + A3 / a3 × m3 ···) / Z) × 1000 A1, A2, A3 ···: Charged amount of polycarboxylic acids (g) a1, a2, a3 ···: Molecular weight of polycarboxylic acids m1, m2, m3 ···: Number of carboxy groups per molecule of polycarboxylic acids Z: Final weight (g) <When there is less polyol> Ester group concentration (mmol / g) = [((B1 / b1 × n1 + B2 / b2 × n2 + B3 / b3 × n3 ···) / Z) × 1000 B1, B2, B3 ···: Charge amount of polyol (g) b1, b2, b3 ···: Molecular weight of polyol n1, n2, n3 ···: Number of hydroxyl groups per molecule of polyol Z: Finished weight (g)

[0072] In addition, the above ester group concentration can also be measured by a known method using NMR or the like. For example, the ester group concentration of the polyester resin (A) can be measured by 1 1H-NMR measurement (proton nuclear magnetic resonance spectroscopy) with a resonance frequency of 400 MHz, 13 13C-NMR measurement (carbon nuclear magnetic resonance spectroscopy).

[0073] Examples of the method for adjusting the above ester group concentration include, for example, a method of selecting a polyol having 4 or less carbon atoms as the polyol, a method of increasing the content of linear carboxylic acids as the polycarboxylic acids, and a method of combining both of them.

[0074] The heat of crystal melting measured by a differential scanning calorimeter for the polyester resin (A) is usually 10 J / g or less, preferably 5 J / g or less, more preferably 2 J / g or less, and particularly preferably no heat of crystal melting. If such heat of crystal melting is too large, crystallinity will appear, and the storage stability of the resin solution will tend to decrease, and the stability and adhesive properties at low temperatures when made into an adhesive sheet will also tend to decrease. The above heat of crystal melting refers to the energy consumed when a crystallized substance is heated and melted, and can be measured by a differential scanning calorimeter DSC.

[0075] Examples of the method for adjusting the above heat of crystal melting include, for example, a method of appropriately using polycarboxylic acids having an alkyl group in the side chain or polyols having an alkyl group in the side chain, and a method of using three or more copolymer monomer components, preferably four or more components.

[0076] The acid value of the above polyester resin (A) is preferably 10 mgKOH / g or less, more preferably 5 mgKOH / g or less, and particularly preferably 2 mgKOH / g or less, from the viewpoint of preventing hydrolysis and improving durability. If the acid value is too large, the durability tends to decrease. To adjust the acid value, for example, increasing the ratio of polyol or adjusting the reaction conditions during the esterification reaction or transesterification reaction can be mentioned. The lower limit of the acid value is usually 0 mgKOH / g.

[0077] The acid value of the above polyester resin (A) is determined by neutralization titration based on JIS K0070. In addition, the acid value in the present invention means the content of carboxy groups in the polyester resin (A). The above carboxy groups include those in the carboxylate ion state in which the carboxy groups are neutralized by a basic compound.

[0078] The polyester resin composition of the present invention preferably contains, together with the above polyester resin (A), a polyvalent isocyanate compound (B), a hydrolysis inhibitor (C), and, if necessary, a tackifier (D), a urethanization catalyst (E), an antioxidant (F), etc.

[0079] <Polyvalent isocyanate compound (B)> The polyester resin composition of the present invention preferably further contains a polyvalent isocyanate compound (B) as a crosslinking agent. By containing the polyvalent isocyanate compound (B), the polyester resin (A) is crosslinked with the polyvalent isocyanate compound (B) to have excellent cohesive strength, and the performance as an adhesive can be improved.

[0080] Examples of such polyvalent isocyanate compounds (B) include aromatic isocyanate crosslinking agents such as tolylene diisocyanate crosslinking agents like 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, xylylene diisocyanate crosslinking agents such as 1,3-xylylene diisocyanate, diphenylmethane crosslinking agents such as diphenylmethane-4,4-diisocyanate, and naphthalene diisocyanate crosslinking agents such as 1,5-naphthalene diisocyanate; alicyclic isocyanate crosslinking agents such as isophorone diisocyanate, 1,4-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, isopropylidene dicyclohexyl-4,4'-diisocyanate, 1,3-diisocyanatomethylcyclohexane, and norbornane diisocyanate; aliphatic isocyanate crosslinking agents such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate; and adducts of the above isocyanate compounds with polyol compounds such as trimethylolpropane, biuret compounds, and isocyanurate compounds of these isocyanate compounds. Note that the above polyisocyanate compounds can also be those in which the isocyanate moiety is blocked with phenol, lactam, etc. These polyvalent isocyanate compounds may be used alone or in combination of two or more.

[0081] The content of such polyvalent isocyanate compound (B) can be appropriately selected according to the molecular weight and intended use of the polyester resin (A). Usually, the reactive groups contained in the polyvalent isocyanate compound (B) are preferably contained in the polyvalent isocyanate compound (B) at a ratio of 0.2 to 10 equivalents, particularly preferably 0.5 to 5 equivalents, and more preferably 0.5 to 3 equivalents, per 1 equivalent of at least one of the hydroxyl group and carboxyl group contained in the polyester resin (A). If the equivalent number of the reactive groups contained in such polyvalent isocyanate compound (B) is too small, the cohesive force tends to decrease, and if it is too large, the flexibility tends to decrease.

[0082] In the reaction of the polyester resin (A) and the polyvalent isocyanate compound (B), organic solvents having no functional groups that react with these components (A) and (B), such as esters like ethyl acetate and butyl acetate, ketones like methyl ethyl ketone and methyl isobutyl ketone, and aromatics like toluene and xylene, can be used. These can be used alone or in combination of two or more.

[0083] <Hydrolysis inhibitor (C)> The above hydrolysis inhibitor (C) is contained to ensure the long-term durability of the polyester resin composition. As the above hydrolysis inhibitor (C), conventionally known ones can be used. For example, compounds that react and bond with the carboxyl group terminals of the above polyester resin (A) can be mentioned. Specifically, for example, compounds containing functional groups such as carbodiimide groups, epoxy groups, oxazoline groups, etc. can be mentioned. Among these, carbodiimide group-containing compounds are preferable in that they have a high effect of eliminating the catalytic activity of protons derived from carboxyl group terminals.

[0084] As the above carbodiimide group-containing compound, usually, a known carbodiimide having one or more carbodiimide groups (-N=C=N-) in the molecule can be used. However, in terms of improving durability under higher temperature and humidity, a compound containing two or more carbodiimide groups in the molecule, that is, a polyvalent carbodiimide compound, is preferable. In particular, a compound containing three or more, further five or more, especially seven or more carbodiimide groups in the molecule is preferable. The number of carbodiimide groups in the molecule is usually 50 or less. If there are too many carbodiimide groups, the molecular structure becomes too large, and the compatibility tends to decrease. It is also preferable to use a high molecular weight polycarbodiimide produced by subjecting diisocyanate to a decarboxylation condensation reaction in the presence of a carbodiimidization catalyst.

[0085] Furthermore, high molecular weight polycarbodiimide in which the terminal isocyanate groups are blocked by a blocking agent is preferred in terms of storage stability. Examples of the blocking agent include compounds having active hydrogen that reacts with isocyanate groups, or compounds having isocyanate groups. For example, monoalcohols, monocarboxylic acids, monoamines, and monoisocyanates having one substituent selected from a carboxy group, an amino group, and an isocyanate group can be mentioned.

[0086] Examples of such high molecular weight polycarbodiimide include those obtained by subjecting the following diisocyanates to a decarboxylation condensation reaction.

[0087] Examples of such diisocyanates include 4,4'-diphenylmethane diisocyanate, 3,3'-dimethoxy-4,4'-diphenylmethane diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, 3,3'-dimethyl-4,4'-diphenyl ether diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1-methoxyphenyl-2,4-diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, tetramethylxylylene diisocyanate, etc. These can be used alone or in combination of two or more. Such high molecular weight polycarbodiimide may be synthesized or a commercially available product may be used.

[0088] Examples of commercially available products of the above carbodiimide group-containing compounds include the Carbodilite (registered trademark) series manufactured by Nisshinbo Chemicals Co., Ltd. Among them, Carbodilite (registered trademark) "V-01", "V-02B", "V-03", "V-04K", "V-04PF", "V-05", "V-07", "V-09", "V-09GB" are preferred in terms of excellent compatibility with organic solvents.

[0089] Examples of the above epoxy group-containing compounds include glycidyl ester compounds and glycidyl ether compounds, etc.

[0090] Specific examples of the glycidyl ester compound include, for example, glycidyl benzoate, glycidyl t-Bu-benzoate, glycidyl p-toluylate, glycidyl cyclohexanecarboxylate, glycidyl pelargonate, glycidyl stearate, glycidyl laurate, glycidyl palmitate, glycidyl behenate, glycidyl versatate, glycidyl oleate, glycidyl linoleate, glycidyl linolenate, glycidyl behenolate, glycidyl stearolate, diglycidyl terephthalate, diglycidyl isophthalate, diglycidyl phthalate, diglycidyl naphthalenedicarboxylate, diglycidyl methylterephthalate, diglycidyl hexahydrophthalate, diglycidyl tetrahydrophthalate, diglycidyl cyclohexanedicarboxylate, diglycidyl adipate, diglycidyl succinate, diglycidyl sebacate, diglycidyl dodecanedioate, diglycidyl octadecanedicarboxylate, triglycidyl trimellitate, tetraglycidyl pyromellitate, etc. These can be used alone or in combination of two or more kinds.

[0091] Specific examples of the glycidyl ether compound include, for example, phenyl glycidyl ether, o-phenyl glycidyl ether, 1,4-bis(β,γ-epoxypropoxy)butane, 1,6-bis(β,γ-epoxypropoxy)hexane, 1,4-bis(β,γ-epoxypropoxy)benzene, 1-(β,γ-epoxypropoxy)-2-ethoxyethane, 1-(β,γ-epoxypropoxy)-2-benzyloxyethane, 2,2-bis-[p-(β,γ-epoxypropoxy)phenyl]propane, and bisglycidyl polyethers obtained by the reaction of bisphenols such as 2,2-bis-(4-hydroxyphenyl)propane and 2,2-bis-(4-hydroxyphenyl)methane with epichlorohydrin. These can be used alone or in combination of two or more kinds.

[0092] As the above oxazoline group-containing compound, bisoxazoline compounds and the like are preferable. Specifically, for example, 2,2'-bis(2-oxazoline), 2,2'-bis(4-methyl-2-oxazoline), 2,2'-bis(4,4-dimethyl-2-oxazoline), 2,2'-bis(4-ethyl-2-oxazoline), 2,2'-bis(4,4'-diethyl-2-oxazoline), 2,2'-bis(4-propyl-2-oxazoline), 2,2'-bis(4-butyl-2-oxazoline), 2,2'-bis(4-hexyl-2-oxazoline), 2,2'-bis(4-phenyl-2-oxazoline), 2,2'-bis(4-cyclohexyl-2-oxazoline), 2,2'-bis(4-benzyl-2-oxazoline), 2,2'-p-phenylene bis(2-oxazoline), 2,2'-m-phenylene bis(2-oxazoline), 2,2'-o-phenylene bis(2-oxazoline), 2,2'-p-phenylene bis(4-methyl-2-oxazoline), 2,2'-p-phenylene bis(4,4-dimethyl-2-oxazoline), 2,2'-m-phenylene bis(4-methyl-2-oxazoline), 2,2'-m-phenylene bis(4,4-dimethyl-2-oxazoline), 2,2'-ethylene bis(2-oxazoline), 2,2'-tetramethylene bis(2-oxazoline), 2,2'-hexamethylene bis(2-oxazoline), 2,2'-octamethylene bis(2-oxazoline), 2,2'-decamethylene bis(2-oxazoline), 2,2'-ethylene bis(4-methyl-2-oxazoline), 2,2'-tetramethylene bis(4,4-dimethyl-2-oxazoline), 2,2'-9,9'-diphenoxyethane bis(2-oxazoline), 2,2'-cyclohexylene bis(2-oxazoline), 2,2'-diphenylene bis(2-oxazoline) and the like can be exemplified. Among these, 2,2'-bis(2-oxazoline) is most preferable from the viewpoint of reactivity with the polyester resin (A). Further, these can be used alone or in combination of two or more.

[0093] As these hydrolysis inhibitors (C), those with lower volatility are preferred, and for this reason, those with a higher number-average molecular weight are preferably used. The number-average molecular weight is usually 300 to 10,000, preferably 1,000 to 5,000. Also, from the viewpoint of hydrolysis resistance, it is preferable to use those with a higher weight-average molecular weight as the hydrolysis inhibitor (C). The weight-average molecular weight of the hydrolysis inhibitor (C) is preferably 500 or more, more preferably 1,000 or more, still more preferably 2,000 or more, and particularly preferably 3,000 or more. The upper limit of the weight-average molecular weight is usually 50,000. If the molecular weight of the hydrolysis inhibitor (C) is too small, the hydrolysis resistance tends to decrease. In addition, if the molecular weight is too large, the compatibility with the polyester resin (A) tends to decrease.

[0094] Among the hydrolysis inhibitors (C), it is preferable to use a carbodiimide group-containing compound. In this case, the carbodiimide equivalent is preferably 50 to 10,000, particularly 100 to 1,000, and even more preferably 150 to 500. The carbodiimide equivalent indicates the chemical formula weight per one carbodiimide group.

[0095] The content of the above hydrolysis inhibitor (C) is preferably 0.01 to 10 parts by weight, particularly preferably 0.1 to 5 parts by weight, and even more preferably 0.2 to 3 parts by weight, based on 100 parts by weight of the above polyester resin (A). If such a content is too much, turbidity tends to occur due to poor compatibility with the polyester resin (A), and if it is too little, sufficient durability tends to be difficult to obtain.

[0096] In addition, the content of the hydrolysis inhibitor (C) is preferably optimized according to the acid value of the polyester resin (A). The molar ratio [(y) / (x)] of the total number of moles (y) of the functional groups of the hydrolysis inhibitor (C) in the polyester resin composition to the total number of moles (x) of the acidic functional groups of the polyester resin (A) in the polyester resin composition is preferably 0.5 ≦ (y) / (x), particularly preferably 1 ≦ (y) / (x) ≦ 1000, and more preferably 1.5 ≦ (y) / (x) ≦ 100. If the molar ratio of (y) to (x) is too low, the wet heat resistance performance tends to decrease. If the molar ratio of (y) to (x) is too high, the compatibility with the polyester resin (A) tends to decrease, and the adhesive strength, cohesive strength, and durability performance tend to decrease.

[0097] <Adhesion promoter (D)> In the present invention, it is preferable to contain an adhesion promoter (D) in terms of improving the adhesion characteristics.

[0098] The adhesion promoter (D) is not particularly limited, and conventionally known ones can be used. Examples of the adhesion promoter (D) include hydrocarbon-based adhesion-promoting resins, terpene-based resins, phenolic resins, rosin-based resins, xylene resins, epoxy resins, polyamide-based resins, ketone-based resins, elastomer-based resins, etc. These may be used alone or in combination of two or more. Among them, hydrocarbon-based adhesion-promoting resins and terpene-based resins are preferable. In addition, it is particularly preferable that the adhesion promoter (D) contains at least one hydrocarbon-based adhesion-promoting resin, and the hydrocarbon-based adhesion-promoting resin is preferably 30% by weight or more, preferably 50% by weight or more, and preferably 70% by weight or more of the total adhesion promoter.

[0099] 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 (such as styrene-olefin copolymers), aliphatic-alicyclic petroleum resins, hydrogenated hydrocarbon resins, coumarone resins, and coumarone-indene resins. Examples of commercially available products include "FTR6100", "FTR6110", "FTR6125", "FTR8100", "FTR8120", "FMR0150", etc. manufactured by Mitsui Chemicals, Inc.

[0100] Examples of the terpene-based resin include terpene resins, terpene phenol resins, and aromatic-modified terpene resins. Specifically, α-pinene polymers, β-pinene polymers, dipentene polymers, and terpene-based resins obtained by phenol modification, aromatic modification, hydrogenation modification, or hydrocarbon modification of these can be used. Examples of commercially available products include "YS Polyster S145", "YS Resin PX1000", "YS Resin PX1250", "YS Polyster T160", "YS Polyster T145", "YS Polyster T130", "YS Resin TO115", "YS Polyster G150", "YS Polyster G125", "YS Polyster U130", "Clearon P125", etc. manufactured by Yasuhara Chemical Co., Ltd. Terpene-based resins are preferred in terms of their good adhesion to non-polar adherends such as polypropylene.

[0101] Examples of the phenolic resin include condensates of various phenols such as phenol, m-cresol, 3,5-xylenol, p-alkylphenol, and resorcinol with formaldehyde. Further, resol obtained by subjecting the phenols and formaldehyde to an addition reaction under an alkaline catalyst, novolak obtained by subjecting the phenols and formaldehyde to a condensation reaction under an acid catalyst, rosin-modified phenolic resins obtained by adding phenol to unmodified or modified rosin or derivatives thereof such as these under an acid catalyst and subjecting them to thermal polymerization, etc. can be used.

[0102] 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, polymerized rosin ester, etc. Specifically, 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 thereof can be used. Examples of commercially available products include "Hariester TF", "Haritack 8LJA", "Haritack PH", "Haritack FK100", "Haritack PCJ", etc. manufactured by Harima Chemicals, Inc.

[0103] The tackifier (D) preferably has an acid value of 30 mgKOH / g or less, particularly preferably 10 mgKOH / g or less, more preferably 6 mgKOH / g or less, and especially preferably 3 mgKOH / g or less. When using a plurality of types of tackifiers (D) in combination, it is preferable that their average is within the above range.

[0104] The softening point of the tackifier (D) (measured by, for example, the ring and ball method) is preferably 80 to 170°C, particularly preferably 90 to 160°C, more preferably 100 to 150°C, still more preferably 120 to 155°C, and especially preferably 135 to 150°C. When the softening point is within the above range, the tack characteristics (adhesive force, cohesive force) can be improved, which is preferable.

[0105] In the present invention, the tackifier (D) is preferably of plant origin in order to keep the biomass degree of the entire polyester resin composition high. Examples of the plant-derived tackifier include terpene resins, rosin-based resins, etc.

[0106] The above-mentioned tackifier (D) preferably contains an aromatic structural unit from the viewpoint of improving cohesive force and compatibility. Examples of the tackifier containing an aromatic structural unit include aromatic hydrocarbon resins, aliphatic-aromatic petroleum resins (such as styrene-olefin copolymers), coumarone resins, coumarone-indene resins, terpene phenol resins, and aromatic-modified terpene resins.

[0107] The content of the tackifier (D) is preferably 2 to 200 parts by weight, more preferably 5 to 150 parts by weight, still more preferably 8 to 100 parts by weight, particularly preferably 10 to 80 parts by weight, and most preferably 20 to 50 parts by weight with respect to 100 parts by weight of the polyester resin (A). When the content is within the above range, the tack characteristics (adhesive force, cohesive force) tend to be improved.

[0108] <Urethane-forming catalyst (E)> From the viewpoint of reaction rate, it is more preferable that the polyester resin composition of the present invention contains a urethane-forming catalyst (E).

[0109] Examples of the urethane-forming catalyst (E) include organometallic compounds and tertiary amine compounds. These can be used alone or in combination of two or more.

[0110] Examples of the above organometallic compounds include zirconium compounds, iron compounds, tin compounds, titanium compounds, lead compounds, cobalt compounds, zinc compounds, etc.

[0111] Examples of the zirconium compounds include zirconium naphthenate and zirconium acetylacetonate. Examples of the iron compounds include iron acetylacetonate and iron 2-ethylhexanoate. Examples of the tin compounds include dibutyltin dichloride, dibutyltin oxide, dibutyltin dilaurate, etc. Examples of the titanium compounds include dibutyltitanium dichloride, tetrabutyl titanate, butoxytitanium trichloride, etc. Examples of the lead compounds include lead oleate, lead 2-ethylhexanoate, lead benzoate, lead naphthenate, etc. Examples of the cobalt compounds include cobalt 2-ethylhexanoate and cobalt benzoate. Examples of the zinc compound include zinc naphthenate, zinc 2-ethylhexanoate, and the like.

[0112] Examples of the tertiary amine compound include triethylamine, triethylenediamine, 1,8-diazabicyclo-(5,4,0)-undecene-7, and the like.

[0113] Among these urethanization catalysts (E), organometallic compounds are preferred, and zirconium compounds are particularly preferred, in terms of excellent reaction rate and pot life of the adhesive layer. Further, it is preferable to use acetylacetone in combination with the urethanization catalyst (E) as a catalyst action inhibitor. By including acetylacetone, it is preferable in terms of suppressing the catalytic action at low temperatures and extending the pot life.

[0114] The content of the urethanization catalyst (E) is preferably 0.0001 to 1 part by weight, particularly preferably 0.001 to 0.1 part by weight, and even more preferably 0.01 to 0.05 part by weight, based on 100 parts by weight of the polyester resin (A). If the content is too small, the aging time until the crosslinking reaction is completed tends to be long, and if it is too large, the adhesive physical properties tend to deteriorate.

[0115] <Antioxidant (F)> It is more preferable to contain an antioxidant (F) in the polyester resin composition of the present invention from the viewpoint of improving the stability of the resin.

[0116] Examples of the antioxidant (F) include hindered phenol antioxidants, amine antioxidants, sulfur antioxidants, phosphate antioxidants, and the like. These may be used alone or in combination of two or more. Among them, it is preferably at least one selected from hindered phenol antioxidants, amine antioxidants, and phosphate antioxidants, and particularly preferably an antioxidant composed of a hindered phenol compound. Examples of the hindered phenol antioxidant include antioxidants having a hindered phenol structure in which a sterically bulky group such as a tertiary butyl group is bonded to at least one of the adjacent carbon atoms of the carbon atom on the aromatic ring to which the hydroxyl group of phenol is bonded.

[0117] The content of the antioxidant (F) is preferably 0.01 to 10 parts by weight, more preferably 0.03 to 8 parts by weight, and still more preferably 0.05 to 5 parts by weight with respect to 100 parts by weight of the polyester resin (A). If such a content is too small, there is a tendency that glue residue on the adherend is likely to occur, and if it is too large, there is a tendency that the adhesive physical properties decrease.

[0118] In the polyester resin composition of the present invention, in addition to the above polyester resin (A), polyvalent isocyanate compound (B), hydrolysis inhibitor (C), tackifier (D), urethanization catalyst (E), and antioxidant (F), within a range not impairing the effects of the present invention, additives such as softeners, ultraviolet absorbers, stabilizers, antistatic agents, etc., and other inorganic or organic fillers, powders such as metal powders and pigments, particulate additives, etc. can be blended. Further, it may contain a small amount of impurities contained in the production raw materials of the constituent components of the polyester resin composition. These can be used alone or in combination of two or more.

[0119] Such a polyester resin composition can be obtained, for example, by preparing the above polyester resin (A) and necessary optional components, etc., and blending and dispersing them during the production of the polyester resin (A), or by blending them into a solution of the polyester resin (A) dissolved in an organic solvent and dispersing them using a mixing roller.

[0120] The polyester resin composition of the present invention preferably has a biomass content of 50% or more from the viewpoint of reducing environmental impact, more preferably 60% or more, still more preferably 70% or more, particularly preferably 80% or more, especially preferably 85% or more, and most preferably 90% or more. The biomass content of the polyester resin composition can be adjusted by adjusting the types and amounts of the polyester resin (A) and other compounding components. The biomass content of the polyester resin composition refers to the ratio of the weight of plant-derived raw materials used in producing the polyester resin composition to the total weight of the polyester resin composition, and can be determined, for example, by the following formula. Biomass content (%) = [(Sum of (biomass content of each plant-derived raw material used in producing the polyester resin composition) × (weight of each plant-derived raw material used in producing the polyester resin composition))] / (total weight of the polyester resin composition)

[0121] Also, the biomass content of the polyester resin composition can be measured by the method using the aforementioned NMR or the method using natural radioactive carbon C-14. Among the above calculation methods, it is sufficient that the value obtained by any method is within the above range.

[0122] The polyester resin composition of the present invention preferably has a recycled carbon usage rate of 50% or more from the viewpoint of reducing environmental impact, more preferably 60% or more, still more preferably 70% or more, particularly preferably 80% or more, especially preferably 85% or more, and most preferably 90% or more. The upper limit is 100%. Here, the recycled carbon usage rate of the polyester resin composition refers to the ratio of the weight of raw materials containing recycled carbon used in producing the polyester resin composition to the total weight of the polyester resin composition. Examples of raw materials containing recycled carbon include plant-derived raw materials, recycled polyethylene terephthalate (recycled PET), etc. The recycled carbon usage rate of the polyester resin composition can be adjusted by adjusting the types and amounts of the polyester resin (A) and other compounding components. In addition, the recycled carbon usage rate of the polyester resin composition can be determined, for example, by the following formula. Recycled carbon usage rate (%) = [(Recycled carbon usage rate of each plant-derived raw material used in manufacturing the polyester resin composition) × (Total weight of each raw material using recycled carbon used in manufacturing the polyester resin composition)] / (Total weight of the polyester resin composition)

[0123] The adhesive composition of the present invention contains the above polyester resin composition, and preferably consists only of the above polyester resin composition. In addition, the adhesive of the present invention is formed by cross-linking the above adhesive composition.

[0124] And the adhesive sheet of the present invention has an adhesive layer containing the above adhesive, and it is preferable that such an adhesive layer is formed on one or both sides of a support substrate. In the present invention, "sheet" is described to include "film" and "tape".

[0125] <Adhesive sheet> The adhesive sheet can be produced, for example, as follows. As a method for manufacturing such an adhesive sheet, it can be manufactured according to a known general method for manufacturing an adhesive sheet. For example, on a substrate, the above adhesive composition is coated and dried, a release sheet is bonded to the opposite adhesive composition layer surface, and if necessary, cured, whereby an adhesive sheet of the present invention having an adhesive layer containing an adhesive is obtained on the substrate.

[0126] In addition, by coating and drying the above adhesive composition on a release sheet, bonding a substrate to the opposite adhesive layer surface, and curing if necessary, the adhesive sheet of the present invention can also be obtained.

[0127] In addition, a substrate-free double-sided adhesive sheet can be manufactured by forming an adhesive layer on a release sheet and bonding a release sheet to the opposite adhesive layer surface.

[0128] When in use, the obtained pressure-sensitive adhesive sheet or the substrate-free double-sided pressure-sensitive adhesive sheet is obtained by peeling the release sheet from the pressure-sensitive adhesive layer and bonding the pressure-sensitive adhesive layer to the adherend.

[0129] Examples of the substrate include sheets made of at least one synthetic resin selected from the group consisting of polyester resins such as polyethylene naphthalate, polyethylene terephthalate, polybutylene terephthalate, and polyethylene terephthalate / isophthalate copolymer; polyolefin resins such as polyethylene, polypropylene, and polymethylpentene; polyfluoroethylene resins such as polyvinyl fluoride, polyvinylidene fluoride, and polyfluoroethylene; polyamides such as nylon 6 and nylon 6,6; vinyl polymers such as polyvinyl chloride, polyvinyl chloride / vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polyvinyl alcohol, and vinylon; cellulose resins such as triacetate cellulose and cellophane; acrylic resins such as polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate, and polybutyl acrylate; polystyrene; polycarbonate; polyarylate; polyimide; and cycloolefin polymer; metal foils of aluminum, copper, and iron; papers such as high-quality paper and glassine paper; and woven or non-woven fabrics made of glass fibers, natural fibers, synthetic fibers, etc. These substrates can be used as a single layer or as a multi-layer in which two or more layers are laminated.

[0130] Among these, substrates made of polyethylene terephthalate and polyimide are particularly preferred, and polyethylene terephthalate is particularly preferred in terms of excellent adhesiveness to the pressure-sensitive adhesive.

[0131] In addition, as the substrate, a foam substrate, for example, a foam sheet made of a foam of a synthetic resin such as polyurethane foam, polyethylene foam, and polyacrylate foam can be used. Among these, polyethylene foam and polyacrylate foam are preferred in terms of excellent followability to the adherend and balance of adhesive strength.

[0132] The thickness of the above-mentioned base material is preferably, for example, 1 to 1000 μm, particularly preferably 2 to 500 μm, and even more preferably 3 to 300 μm.

[0133] As the above-mentioned release sheet, for example, a sheet made of various synthetic resins exemplified by the above-mentioned base material, paper, cloth, a non-woven fabric, etc. that have been subjected to a release treatment can be used. As the release sheet, it is preferable to use a silicone-based release sheet.

[0134] As the coating method of the above-mentioned adhesive composition, for example, a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, a spray coater, a comma coater, etc. may be used.

[0135] As the conditions of the above-mentioned curing treatment, the temperature is usually room temperature (23 °C) to 70 °C, and the time is usually 1 to 30 days. Specifically, for example, it may be carried out under conditions such as 1 to 20 days at 23 °C, preferably 3 to 14 days at 23 °C, 1 to 10 days at 40 °C, etc.

[0136] Also, as the 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.

[0137] The thickness of the adhesive layer of the above-mentioned adhesive sheet and the substrate-less double-sided adhesive sheet is preferably 2 to 500 μm, particularly preferably 5 to 200 μm, and even more preferably 10 to 100 μm. If the thickness of such an adhesive layer is too thin, the adhesive strength tends to decrease. If it is too thick, it becomes difficult to coat uniformly, and there is a tendency for problems such as air bubbles to enter the coating film to easily occur. In addition, when considering impact absorbency, it is preferably 50 μm or more.

[0138] Incidentally, the thickness of the above-mentioned adhesive layer is obtained by subtracting the measured value of the thickness of the constituent members other than the adhesive layer from the measured value of the thickness of the entire adhesive sheet using "ID-C112B" manufactured by Mitutoyo Corporation.

[0139] Regarding the gel fraction of the pressure-sensitive adhesive layer of the above-mentioned pressure-sensitive adhesive sheet, from the viewpoints of durability performance and adhesive strength, it is preferably 10% by weight or more, particularly preferably 20 to 80% by weight, and even more preferably 30 to 70% by weight. If the gel fraction is too low, the cohesive force decreases, and the holding force tends to decrease. In addition, if the gel fraction is too high, the adhesive strength tends to decrease due to the increase in the cohesive force.

[0140] The above gel fraction serves as a measure of the degree of crosslinking and is calculated, for example, by the following method. That is, a pressure-sensitive adhesive sheet (one without a release sheet) in which a pressure-sensitive adhesive layer is formed on a polymer sheet as a base material (for example, a PET film, etc.) is wrapped with a 200-mesh SUS wire mesh and immersed in toluene at 23°C for 24 hours. The weight percentage of the insoluble pressure-sensitive adhesive component remaining in the wire mesh after immersion with respect to the weight of the pressure-sensitive adhesive component before immersion is defined as the gel fraction. However, the weight of the base material should be subtracted.

[0141] Furthermore, such a pressure-sensitive adhesive sheet may be provided with a release sheet on the outside of the pressure-sensitive adhesive layer for protection as needed. Also, in a pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive layer is formed on one side of the base material, it is also possible to protect the pressure-sensitive adhesive layer by performing a peeling treatment on the surface of the base material opposite to the pressure-sensitive adhesive layer and using the peeled surface.

[0142] The pressure-sensitive adhesive of the present invention can be used for bonding various members, and in particular, it is used for single-sided or double-sided pressure-sensitive adhesive sheets for bonding optical members, single-sided or double-sided pressure-sensitive adhesive sheets for fixing members of portable electronic devices, and fixing electronic members, etc.

Examples

[0143] Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the examples, "parts" and "%" indicate weight basis.

[0144] Also, regarding the measurement of the number average molecular weight, weight average molecular weight, biomass content, recycled carbon usage rate, glass transition temperature of the polyester resin, and the gel fraction of the adhesive layer, and the biomass content and recycled carbon usage rate of the polyester resin composition in the following examples, the measurements were carried out according to the aforementioned methods.

[0145] The polyester resin was produced by the following method (see Table 1).

[0146] [Examples 1 to 8, Comparative Examples 1 to 5] [Production of Polyester Resins (A) [A-1 to A-8], (A') [A'-1 to A'-5]] Polycarboxylic acids and polyols as shown in Table 1 were charged into a reaction vessel equipped with a thermometer, stirrer, rectifying column, nitrogen inlet tube, and vacuum device. As a catalyst, tetrabutyl titanate was charged at 0.2 mmol / mol based on the polycarboxylic acids. The temperature was gradually raised to 240 to 250 °C, and an esterification reaction was carried out over 4 hours. Then, the internal temperature was raised to 260 °C, tetrabutyl titanate was charged at 0.2 mmol / mol based on the polycarboxylic acids, the pressure was reduced to 1.33 to 2.66 hPa, and a polymerization reaction was carried out over 2 to 3 hours to produce the polyester resin (A) or (A'). The composition ratios, physical properties, etc. of the obtained polyester resin (A) or (A') were as shown in Table 2 below. In the above production, the plant-derived raw materials were hydrogenated distilled dimer acid, 2,5-furandicarboxylic acid, sebacic acid, and 1,3-propanediol. Also, a part of terephthalic acid and ethylene glycol was derived from PET.

[0147]

Table 1

[0148]

Table 2

[0149] Next, prior to preparing the polyester resin composition (adhesive composition), each component was prepared as follows.

[0150] [Polyvalent isocyanate compound (B)] · Polyvalent isocyanate compound (B-1): "Coronate L55E, solid content concentration 55%" (manufactured by Tosoh Corporation)

[0151] [Hydrolysis inhibitor (C)] · Carbodiimide compound (C-1): "Carbodilite V-09GB, solid content concentration 70%" (manufactured by Nisshinbo Chemical Inc.)

[0152] Using the above polyester resin, crosslinking agent, and hydrolysis inhibitor, a polyester resin composition (adhesive composition) was prepared according to the compounding compositions shown in Tables 3 and 4 below, and an adhesive sheet was produced.

[0153] [Examples 1-1 to 8-2, Comparative Examples 1-1 to 5-2] The polyester resin [(A) or (A')] obtained above was diluted with ethyl acetate to a solid content concentration of 50%, and a polyvalent isocyanate compound (B-1) and a carbodiimide compound (C-1) were blended at the blending ratios (solid content ratios) shown in Table 3. Further, 0.02 part (solid content) of a zirconium compound (Matsumoto Fine Chemical Co., Ltd.'s "Organix ZC-150") diluted with acetylacetone to a solid content concentration of 1% as a urethanization catalyst was added, and the mixture was stirred and mixed to obtain a polyester resin composition (adhesive composition). The obtained adhesive composition was applied to a polyethylene terephthalate (PET) film (thickness 38 μm) so that the thickness after drying would be about 25 μm, and then dried at 100°C for 3 minutes to form an adhesive layer. Thereafter, a release-treated PET film (release film) was adhered to the adhesive layer to protect its surface, and the film was cured in an atmosphere at 40°C for 10 days to obtain an adhesive sheet.

[0154] The following evaluations were performed on the obtained adhesive sheets of the examples and comparative examples. The evaluation results are shown in Tables 3 and 4 below.

[0155] <Initial adhesive strength (peel strength) (against SUS)> An SUS-BA plate was prepared as the adherend. After cutting the adhesive sheet obtained above into 25 mm × 200 mm in an environment of 23°C and 50% RH, the release film was peeled off, the adhesive layer side was brought into contact with the SUS-BA plate, and a 2 kg roller was reciprocated to apply pressure for sticking. Then, after standing still for 30 minutes in the same atmosphere, the 180-degree peel strength (N / 25 mm) was measured at a peel rate of 300 mm / min using an autograph (manufactured by Shimadzu Corporation, Autograph AGS-H 500N), and the peeling state was observed visually.

[0156] <Adhesive strength (peel strength) after 72 hours (against SUS)> An SUS-BA plate was prepared as the adherend. After cutting the adhesive sheet obtained above into 25 mm × 200 mm in an environment of 23°C and 50% RH, the release film was peeled off, the adhesive layer side was brought into contact with the SUS-BA plate, and a 2 kg roller was reciprocated to apply pressure for sticking. Then, after standing still for 72 hours in the same atmosphere, the 180-degree peel strength (N / 25 mm) was measured at a peel rate of 300 mm / min using an autograph (manufactured by Shimadzu Corporation, Autograph AGS-H 500N), and the peeling state was observed visually. Also, evaluation was carried out according to the following criteria. (Evaluation criteria) ◎ ··· The peel strength is 20 N / 25 mm or more and interfacial peeling occurred. 〇 ··· The peel strength is 20 N / 25 mm or more and cohesive failure occurred. 〇 ··· The peel strength is 15 N / 25 mm or more and less than 20 N / 25 mm and interfacial peeling occurred. △ ··· The peel strength is 15 N / 25 mm or more and less than 20 N / 25 mm and cohesive failure occurred. × ··· The peel strength is less than 15 N / 25 mm (regardless of the peeling state).

[0157] <Initial adhesive strength (peel strength) (against PP)> A PP plate was prepared as the adherend. After cutting the pressure-sensitive adhesive sheet obtained above into pieces of 25 mm × 200 mm under the environment of 23 °C and 50% RH, the release film was peeled off, the pressure-sensitive adhesive layer side was brought into contact with the PP plate, and a 2-kg roller was reciprocated for pressure bonding. Then, after standing still for 30 minutes under the same atmosphere, using an autograph (manufactured by Shimadzu Corporation, Autograph AGS-H 500N), the 180-degree peel strength (N / 25 mm) was measured at a peel rate of 300 mm / min, and the peel state was observed visually. Also, evaluation was conducted according to the following criteria. (Evaluation Criteria) 〇 ··· The peel strength was 10 N / 25 mm or more and interfacial peeling occurred. △ ··· The peel strength was 10 N / 25 mm or more and cohesive failure occurred. △ ··· The peel strength was 5 N / 25 mm or more and less than 10 N / 25 mm and interfacial peeling occurred. × ··· The peel strength was 5 N / 25 mm or more and less than 10 N / 25 mm and cohesive failure occurred. × ··· The peel strength was less than 5 N / 25 mm (regardless of the peel state).

[0158] <Retention Force (Cohesive Force)> The pressure-sensitive adhesive sheet obtained above was pasted according to JIS Z-0237 with SUS304 as the adherend and a pasting area of 25 mm × 25 mm. After standing still at 80 °C for 20 minutes, a 1-kg load was applied to those that did not fall until dropping or those that did not fall even after standing still for 24 hours, and the displacement after 24 hours was measured, and evaluation was conducted according to the following criteria. (Evaluation Criteria) ◎ ··· It did not fall after standing still for 24 hours and the displacement was within 1 mm. ○ ··· It did not fall even after standing still for 24 hours, but the displacement exceeded 1 mm. × ··· It fell during the 24-hour standing still.

[0159]

Table 3

[0160]

Table 4

[0161] From the results in Table 3 above, the pressure-sensitive adhesive sheets of Examples 1-1 to 8-2 prepared from the pressure-sensitive adhesive compositions containing the polyester resin compositions of Examples 1 to 8 in Table 2 were excellent in the initial and after-time adhesiveness to metal adherends, and further had desired adhesiveness even to adherends difficult to adhere such as polyolefin resins, and were excellent in the balance between adhesive strength and holding power. Also, from the results in Table 4 above, in the pressure-sensitive adhesive sheets of Comparative Examples 1-1 to 1-3 and 5-1 to 5-2 prepared from the pressure-sensitive adhesive compositions containing the polyester resin compositions of Comparative Examples 1 and 5 in Table 2, which do not contain aromatic dicarboxylic acids as copolymer components of polycarboxylic acids and contain only dimer acid, the adhesive strength over time was particularly low. Furthermore, in the pressure-sensitive adhesive sheets of Comparative Examples 2-1 to 4-1 prepared from the pressure-sensitive adhesive compositions containing the polyester resin compositions of Comparative Examples 2 to 4 in Table 2, which contain aromatic dicarboxylic acids but have too much aromatic dicarboxylic acids, the pressure-sensitive adhesive properties were inferior to both metal and polyolefin adherends, and the effects of the present invention could not be fully satisfied.

Industrial Applicability

[0162] The polyester resin composition, the pressure-sensitive adhesive composition containing the same, and the pressure-sensitive adhesive of the present invention have an excellent effect on the pressure-sensitive adhesive properties to various adherends such as metal and plastic even when using a polyester resin with a high degree of biodegradable plastic, and are used for single-sided or double-sided pressure-sensitive adhesive sheets used for bonding optical members, single-sided or double-sided pressure-sensitive adhesive sheets for fixing members of portable electronic devices and for fixing electronic members, etc.

Claims

1. A polyester resin composition containing a polyester resin (A), wherein the polyester resin (A) contains a structural unit derived from at least one compound (a1) of dimer acids and dimer diols, and a structural unit derived from an aromatic compound (a2), when the compound (a1) is dimer acids, the content of dimer acids is 35 to 90 mol% based on the total polycarboxylic acids, when the compound (a1) is dimer diols, the content of dimer diols is 35 to 90 mol% based on the total polyols, when the aromatic compound (a2) is aromatic polycarboxylic acids, the content of aromatic polycarboxylic acids is 10 to 43 mol% based on the total polycarboxylic acids, when the aromatic compound (a2) is aromatic polyols, the content of aromatic polyols is 10 to 43 mol% based on the total polyols, the weight average molecular weight of the polyester resin (A) measured by high performance liquid chromatography is 40,000 to 500,000, and the ratio (X1 / X2) of the molar concentration (X1) of the structural unit derived from the compound (a1) to the molar concentration (X2) of the structural unit derived from the aromatic compound (a2) is greater than 2.

0. A polyester resin composition characterized by this.

2. The polyester resin (A) contains a structural unit derived from an aliphatic polyol, and among the structural units derived from the aliphatic polyol, 10 mol% or more is an acyclic aliphatic diol having 2 to 20 carbon atoms. The polyester resin composition according to Claim 1, characterized by this.

3. The aromatic compound (a2) is aromatic polycarboxylic acids. The polyester resin composition according to Claim 1 or 2, characterized by this.

4. The number average molecular weight of the polyester resin (A) is 3,000 or more. The polyester resin composition according to any one of Claims 1 to 3, characterized by this.

5. The biomass degree of the polyester resin (A) is 50% or more. The polyester resin composition according to any one of Claims 1 to 4, characterized by this.

6. Furthermore, it contains a polyisocyanate compound (B). The polyester resin composition according to any one of Claims 1 to 5, characterized by this.

7. Furthermore, it contains a hydrolysis inhibitor (C). The polyester resin composition according to any one of Claims 1 to 6, characterized by this.

8. An adhesive composition containing the polyester resin composition according to any one of Claims 1 to 7.

9. An adhesive characterized in that the adhesive composition according to Claim 8 is crosslinked.

10. An adhesive sheet having an adhesive layer containing the adhesive according to Claim 9.

11. A double-sided adhesive sheet having an adhesive layer containing the adhesive according to Claim 9.

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