JP2021134354A - Polyester-based adhesive composition, polyester-based adhesive, and adhesive sheet - Google Patents

Abstract

To provide an adhesive composition excellent in adhesive force to various adherends and also excellent in holding power and tackiness.SOLUTION: A polyester-based adhesive composition contains: a polyester-based resin (A) having a structural unit derived from a polycarboxylic acid (a1) and a structural unit derived from a polyol (a2); and a petroleum resin-based tackifier (B) having a number average molecular weight of 400-8,000. The content of the petroleum resin-based tackifier (B) having a number average molecular weight of 400-8,000 is 0.01-50 pts.wt. based on 100 pts.wt. of the polyester-based resin (A).SELECTED DRAWING: None

Description

The present invention relates to a polyester-based pressure-sensitive adhesive composition, a polyester-based pressure-sensitive adhesive, and a pressure-sensitive adhesive sheet. It relates to an adhesive and an adhesive sheet.

Conventionally, it has been known that a polyester resin has excellent chemical resistance, plasticizer resistance, mechanical strength, etc. by combining a polyvalent carboxylic acid component and a polyol component, and is an adhesive (adhesive). It is also being studied in the field of adhesives).

Further, in recent years, with the miniaturization and thinning of parts and members, high adhesive strength is required even in a small area of the adhesive, and as a method for improving the adhesive strength, for example, in Patent Document 1, A polyester-based pressure-sensitive adhesive composition containing polyester and a pressure-sensitive adhesive has been proposed.
Further, in Patent Document 2, a polyester-based pressure-sensitive adhesive composition containing a polyester, a hydrolysis resistance agent, a pressure-sensitive adhesive, and a cross-linking agent, wherein the pressure-sensitive adhesive having a specific acid value and a specific softening point is polyester 100. A polyester-based pressure-sensitive adhesive composition containing 20 to 100 parts by weight with respect to parts by weight has been proposed.

Japanese Unexamined Patent Publication No. 2014-169419 Japanese Unexamined Patent Publication No. 2015-134906

However, in the disclosed techniques of Patent Document 1 and Patent Document 2, a tackifier having a high softening point such as a rosin ester or a terpene resin is blended. Generally, a tackifier having a high softening point is often blended in order to impart cohesive force at a high temperature, but such a tackifier reduces tackiness at room temperature, yellowing, cloudiness, etc. There were still problems such as changes in the appearance of the product.
Further, the terpene resin-based pressure-sensitive adhesives described in Patent Documents 1 and 2 have low polarities, and there is a concern about compatibility with polyester-based resins.

Therefore, it is an object of the present invention to provide a polyester-based pressure-sensitive adhesive composition having excellent adhesive strength to various adherends, and further excellent holding power and tackiness under such a background. It is an object of the present invention to provide a polyester-based pressure-sensitive adhesive and a pressure-sensitive adhesive sheet.

However, as a result of intensive studies in view of such circumstances, the present inventor has a petroleum resin having a specific number average molecular weight as a pressure-sensitive adhesive in a polyester-based pressure-sensitive adhesive composition containing a polyester-based resin and a pressure-sensitive adhesive. The present invention has been completed by finding that a polyester-based pressure-sensitive adhesive composition having excellent adhesive strength to various adherends and further excellent holding power and tackiness can be obtained by using a system-based adhesive-imparting agent in a specific content ratio. bottom.

That is, the present invention relates to a polyester resin (A) having a structural unit derived from a polyvalent carboxylic acid (a1) and a structural unit derived from a polyol (a2), and a petroleum resin pressure-sensitive adhesive having a number average molecular weight of 400 to 8000. The content of the petroleum resin-based pressure-sensitive adhesive (B) containing B) and having a number average molecular weight of 400 to 8000 is 0.01 to 50 parts by weight with respect to 100 parts by weight of the polyester resin (A). The first gist is a polyester-based pressure-sensitive adhesive composition.

Further, the present invention has a polyester-based pressure-sensitive adhesive obtained by cross-linking the polyester-based pressure-sensitive adhesive composition as a second gist, and a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing the polyester-based pressure-sensitive adhesive as a third gist. do.

In polyester-based pressure-sensitive adhesives, generally, a pressure-sensitive adhesive is blended in order to improve the adhesive strength to the adherend. In this case, conventionally known tackifiers such as terpene resin, phenol resin, rosin resin, aliphatic petroleum resin, aromatic petroleum resin, copolymer petroleum resin, alicyclic petroleum resin, xylene Resins, epoxy resins, polyamide resins, ketone resins, elastomer resins, etc. can be used, but usually, terpene resins and rosin resins are often used from the viewpoint of adhesive strength and tackiness. There are problems that the compatibility with the polyester resin is poor and that hydrolysis proceeds due to the high acid value. Further, since petroleum resin has low polarity, it is considered that it cannot be practically used because it is inferior in compatibility with a highly polar polyester resin and its tackiness is lowered. However, in the present invention, when the polyester resin is used as the base resin, when the polyester resin is intentionally blended with the petroleum resin adhesive, the adhesive strength and tackiness do not unexpectedly decrease, but rather. It is excellent in adhesive strength, holding power and tackiness, and the object of the present invention can be achieved.

The polyester-based pressure-sensitive adhesive composition of the present invention comprises a polyester-based resin (A) having a structural unit derived from a polyvalent carboxylic acid (a1) and a structural unit derived from a polyol (a2), and a petroleum resin having a number average molecular weight of 400 to 8000. The content of the petroleum resin-based pressure-sensitive adhesive (B) containing the system-based pressure-sensitive adhesive (B) and having a number average molecular weight of 400 to 8000 is 0.01 to 100 parts by weight of the polyester-based resin (A). 50 parts by weight. Therefore, it has excellent adhesive strength to various adherends, and also has excellent holding power and tackiness, and is particularly useful as an adhesive for electronic members and optical members.

Hereinafter, the configuration of the present invention will be described in detail, but these are examples of desirable embodiments.
In the present invention, the "carboxylic acids" include, in addition to carboxylic acids, carboxylic acid derivatives such as carboxylic acid salts, carboxylic acid anhydrides, carboxylic acid halides, and carboxylic acid esters.

The polyester-based pressure-sensitive adhesive composition of the present invention contains a polyester-based resin (A) and a petroleum resin-based pressure-sensitive adhesive (B) having a specific number average molecular weight in a specific content ratio. Hereinafter, each component contained in the polyester-based pressure-sensitive adhesive composition of the present invention will be described.

<Polyester resin (A)>
The polyester-based resin (A) has a structural unit derived from the polyvalent carboxylic acids (a1) and a structural unit derived from the polyol (a2) as a resin composition, and usually, the polyvalent carboxylic acids (a1) are used as a constituent raw material. ) And the copolymerization component containing the polyol (a2).

[Multivalent carboxylic acids (a1)]
Examples of the polyvalent carboxylic acids (a1) used as a constituent raw material of the polyester resin (A) include divalent dicarboxylic acids and trivalent or higher polyvalent carboxylic acids, and the polyester resin (A) may be used. Dicarboxylic acids are preferably used because they can be stably obtained. The polyvalent carboxylic acids (a1) can be used alone or in combination of two or more.

Examples of the dicarboxylic acids include malonic acids, dimethylmalonic acids, succinic acids, glutaric acids, adipic acids, trimethyladiponic acids, pimeric acids, 2,2-dimethylglutaric acids, azelaic acids, sebacic acids, fumaric acids, and maleic acids. , Itaconic acids, thiodipropionic acids, diglycolic acids, 1,9-nonandicarboxylic acids, and other aliphatic dicarboxylic acids;
Phtalic acids, terephthalic acids, isophthalic acids, benzylmalonic acids, diphenic acids, 4,4'-oxydibenzoic acids, 1,8-naphthalenedicarboxylic acids, 2,3-naphthalenedicarboxylic acids, 2,7-naphthalenedicarboxylic acids, etc. Aromatic dicarboxylic acids such as naphthalenedicarboxylic acids (a1-1);
Oil rings of 1,3-cyclopentanedicarboxylic acids, 1,2-cyclohexanedicarboxylic acids, 1,3-cyclopentanedicarboxylic acids, 1,4-cyclohexanedicarboxylic acids, 2,5-norbornanedicarboxylic acids, adamantandicarboxylic acids, etc. Group dicarboxylic acids;
Structural units derived from dimer acids (mainly those having 36 to 44 carbon atoms) derived from oleic acid, linoleic acid, linolenic acid, erucic acid and the like; and the like.

Examples of the trivalent or higher valent carboxylic acids include trimesic acids, pyromellitic acids, adamantane tricarboxylic acids, trimesic acids and the like.

Further, as the polyvalent carboxylic acid (a1), a hydrogenated polybutadiene structure-containing compound may be used, for example, 1,2-polybutadienedicarboxylic acid, 1,4-polybutadienedicarboxylic acid, 1,4-polyisopregenicarboxylic acid. Examples thereof include polybutadiene-based polyvalent carboxylic acids such as, and saturated hydrocarbon-based polyvalent carboxylic acids in which the double bonds of these polybutadiene-based polyvalent carboxylic acids are saturated with hydrogen, halogen, or the like. Furthermore, polyvalent carboxylic acids obtained by copolymerizing polybutadiene-based polyvalent carboxylic acids with olefin compounds such as styrene, ethylene, vinyl acetate, and acrylic acid esters, hydrogenated polyvalent carboxylic acids, and the like can also be used. Among them, hydrocarbon-based polybutadiene polyvalent carboxylic acids having a high degree of saturation are preferable, those having a number average molecular weight of 300 to 30,000, particularly 500 to 10000, and further preferably 800 to 5000, and the average functional number of carboxy groups is high. Those of 1.5 to 3 are preferable.

As the hydrogenated polybutadiene structure-containing compound, the larger the ratio of the 1, 2 binding sites in the 1, 2 binding sites and the 1, 4 binding sites in the hydrogenated polybutadiene structure, the better the adhesiveness to the polyolefin substrate. It is preferable in that respect. Further, the 1, 2 binding sites in the hydrogenated polybutadiene structure are preferably 25 to 100%, particularly preferably 50 to 100%, and particularly preferably 75 to 100%.

Among the above-mentioned polyvalent carboxylic acids (a1), the aromatic dicarboxylic acid (a1-1) is preferable from the viewpoint of excellent adhesive strength and holding power.

Further, among the above aromatic dicarboxylic acids (a1-1), it is preferable to include asymmetric aromatic dicarboxylic acids (a1-1-1) from the viewpoint of lowering the crystallinity of the polyester resin (A). Examples of the asymmetric aromatic dicarboxylic acids (a1-1-1) include phthalic acids, isophthalic acids, 1,8-naphthalenedicarboxylic acids, 2,3-naphthalenedicarboxylic acids, 2,7-naphthalenedicarboxylic acids and the like. Of these, isophthalic acids are particularly preferable in terms of reactivity.

The content of the asymmetric aromatic dicarboxylic acids (a1-1-1) is preferably 0.1 to 70 mol%, more preferably 0, based on the total polyvalent carboxylic acids (a1). It is 5 to 60 mol%, more preferably 1 to 50 mol%, particularly preferably 2 to 40 mol%, particularly preferably 3 to 30 mol%, and most preferably 5 to 20 mol%. If the content is too small, the resin tends to crystallize and sufficient adhesive performance tends not to be obtained, and if it is too large, the initial adhesive force (tack) tends to decrease.

Further, in the present invention, as polyvalent carboxylic acids (a1), aliphatic dicarboxylic acids (a1-2) having 4 or more carbon atoms (including carbon of carboxy group) from the viewpoint of improving initial adhesive strength (tack). It is preferable to contain an aliphatic dicarboxylic acid having 6 to 12 carbon atoms (including carbon of a carboxy group), and it is particularly preferable to contain adipic acid, sebacic acid, and azelaic acid. It is particularly preferable to contain sebacic acids from the viewpoint of excellent adhesive strength when the petroleum resin-based tackifying resin (B) described later is used.

The content of the aliphatic dicarboxylic acid (a1-2) having 4 or more carbon atoms is preferably 5 to 100 mol%, more preferably 20 to 99, based on the total polyvalent carboxylic acid (a1). It is mol%, more preferably 40 to 98 mol%, particularly preferably 60 to 97 mol%, and particularly preferably 80 to 95 mol%. If the content is too small, the glass transition temperature of the polyester resin (A) becomes too high, and there is a tendency that sufficient adhesive strength cannot be obtained. If the amount is too large, the resin tends to crystallize and sufficient adhesive performance cannot be obtained.

In the present invention, from the viewpoint of adhesive physical properties, asymmetric aromatic dicarboxylic acids (a1-1-1) and aliphatic dicarboxylic acids having 4 or more carbon atoms (a1-2) are used in combination as polyvalent carboxylic acids (a1). It is also preferable to do so. The content ratio (molar ratio) of the asymmetric aromatic dicarboxylic acids (a1-1-1) and the aliphatic dicarboxylic acids (a1-2) having 4 or more carbon atoms is (a1-1-1) / (a1-2). = 0.1 / 99.9 to 70/30, more preferably 0.5 / 99.5 to 60/40, still more preferably 1/99 to 50/50, and particularly preferably 2/98. ~ 40/60, particularly preferably 3/97 to 30/70, most preferably 5/95 to 20/80.

In addition, for the purpose of increasing the number of branch points in the polyester resin (A), polyvalent carboxylic acids having a trivalent value or higher can be used, and among them, trimellitic acids are used because gelation is relatively unlikely to occur. Is preferable.

The content of the trivalent or higher polyvalent carboxylic acids is preferably 10 mol% or less, particularly preferably 10 mol% or less, based on the total polyvalent carboxylic acids (a1) in that the cohesive force of the pressure-sensitive adhesive can be enhanced. It is 0.1 to 5 mol%, and if the content is too large, gelation tends to occur easily during the production of the polyester resin (A).

[Polyprethane (a2)]
Examples of the polyol (a2) used as a constituent raw material of the polyester resin (A) include divalent diols and trivalent or higher valent polyols. The polyol (a2) can be used alone or in combination of two or more.

Examples of the diol include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 2,4-dimethyl-2-ethylhexane-1,3-diol, and 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-Butandiol, 1,4-Butanediol, 1,5-Pentanediol, 1,6-Hexanediol, 3-Methyl-1,5-Pentanediol, 2,2,4 An aliphatic diol such as -trimethyl-1,6-hexanediol;
1,2-Cyclohexanedimethanol, 1,3-Cyclohexanedimethanol, 1,4-Cyclohexanedimethanol, spiroglycol, tricyclodecanedimethanol, adamantandiol, 2,2,4,4-tetramethyl-1,3 -Alicyclic diols such as cyclobutanediol;
4,4'-thiodiphenol, 4,4'-methylenediphenol, bisphenol, bisphenol fluorene, 4,4'-dihydroxybiphenyl, o-, m- and p-dihydroxybenzene, 2,5-naphthalenediol, p. Aromatic diols such as -xylenediol; and these ethylene oxide and propylene oxide adducts.
Further, fatty acid esters derived from castor oil, dimerdiol derived from oleic acid, erucic acid and the like, glycerol monostearate and the like can be mentioned.

Examples of the trivalent or higher-valent polyol include pentaerythritol, dipentaerythritol, tripentaerythritol, glycerin, trimethylolpropane, trimethylolethane, 1,3,6-hexanetriol, and adamantanetriol.

Further, as the polyol (a2), a hydrogenated polybutadiene polyol (a2-1) can be used.
The hydrogenated polybutadiene polyol (a2-1) is, for example, a polybutadiene-based polyol such as 1,2-polybutadiene polyol, 1,4-polybutadiene polyol, or 1,4-polyisoprene polyol, or a double of these polybutadiene-based polyols. Examples thereof include saturated hydrocarbon-based polyols whose bonds are saturated with hydrogen, halogen, or the like. Further, a polyol obtained by copolymerizing an olefin compound such as styrene, ethylene, vinyl acetate, or acrylic acid ester with a polybutadiene-based polyol, a hydrogenated polyol thereof, or the like can also be used. Among them, a hydrocarbon-based polybutadiene polyol having a high degree of saturation is preferable, the number average molecular weight is preferably 300 to 30,000, more preferably 500 to 10000, still more preferably 800 to 5000, and the average functional number of hydroxyl groups is 1. It is preferably 5 to 3.

As the hydrogenated polybutadiene polyol (a2-1), the one having a larger proportion of 1,2 binding sites in the 1,2 binding sites and the 1,4 binding sites in the hydrogenated polybutadiene structure has more adhesiveness to the polyolefin substrate. It is preferable in that it is excellent in. Further, the 1, 2 binding sites in the hydrogenated polybutadiene structure are preferably 25 to 100%, particularly preferably 50 to 100%, and particularly preferably 75 to 100%.

Among the above polyols (a2), it is preferable to use a hydrogenated polybutadiene polyol (a2-1) from the viewpoint of excellent adhesion to a polyolefin base material.

The content of the hydrogenated polybutadiene polyol (a2-1) is preferably 0.001 to 15 mol%, more preferably 0.005 to 10 mol%, still more preferably 0.005 to 10 mol% with respect to the polyol (a2). It is 0.01 to 5 mol%, particularly preferably 0.05 to 2 mol%, and particularly preferably 0.1 to 1 mol%. If the content is too small, the adhesiveness to the polyolefin substrate tends to decrease, and if it is too large, the compatibility tends to decrease.

Further, it is preferable to contain the branched structure-containing polyol (a2-2) as the polyol (a2) from the viewpoint of increasing the number of branching points and destroying the crystallinity. Examples of the branched structure-containing polyol (a2-2) include neopentyl glycol, 2-methyl-1,3-propanediol, 2-methyl-2-ethyl-1,3-propanediol, and 2,2-diethyl-. 1,3-Propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2- Methyl-2,4-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,3,5-trimethyl-1,3-pentanediol, 2-methyl-1,6-hexanediol, dimerdiol And so on. Of these, neopentyl glycol is particularly preferable.
The branched structure-containing polyol (a2-2) excludes the hydrogenated polybutadiene polyol (a2-1) described above.

The content of the branched structure-containing polyol (a2-2) is preferably 5 to 100 mol%, more preferably 10 to 90 mol%, still more preferably 20 to 80 mol% with respect to the entire polyol (a2). %, Especially preferably 30 to 70 mol%, particularly preferably 40 to 60 mol%. If the content is too small, the resin tends to crystallize and it tends to be difficult to obtain sufficient adhesive performance. If the amount is too large, the reaction time tends to be long in the production of the polyester resin (A).

On the other hand, as the polyol (a2), it is preferable to contain a linear polyol (a2-3) from the viewpoint of reactivity, and a linear polyol having 2 to 40 carbon atoms is more preferable. Examples of such linear polyol (a2-3) include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, and dipropylene glycol. , 1,9-Nonandiol, 1,10-decanediol, 1,12-dodecanediol, and other aliphatic glycols. Of these, ethylene glycol, 1,4-butanediol, and 1,6-hexanediol are particularly preferable.

The content of the linear polyol (a2-3) is preferably 5 to 100 mol%, more preferably 10 to 90 mol%, still more preferably 20 to 80 mol% with respect to the entire polyol (a2). , Particularly preferably 30-60 mol%. If the content is too small, it tends to be difficult to obtain stable resin formation.

It is also preferable to use a trivalent or higher polyol in the polyester resin (A) for the purpose of increasing branching points. Examples of the trivalent or higher polyol include pentaerythritol, dipentaerythritol, tripentaerythritol, and glycerin. Examples thereof include trimethylolpropane, trimethylolethane, 1,3,6-hexanetriol, and adamantantriol.

The content of the trivalent or higher polyol is preferably 20 mol% or less, more preferably 0.1 to 10 mol%, and particularly preferably 0.5, based on the total polyol (a2). ~ 5 mol%. If the content is too large, it tends to be difficult to produce the polyester resin (A).

The polyester resin (A) used in the present invention is produced by arbitrarily selecting the polyvalent carboxylic acids (a1) and the polyol (a2) and subjecting them to a polycondensation reaction in the presence of a catalyst by a known method. NS.

The mixing ratio of the polyvalent carboxylic acid (a1) and the polyol (a2) is preferably 1 to 3 equivalents, and particularly preferably 1.1, per 1 equivalent of the polyvalent carboxylic acid (a1). ~ 2 equivalents. If the compounding ratio of the polyol (a2) is too small, the acid value tends to be high and it tends to be difficult to increase the molecular weight, and if it is too large, the yield tends to decrease.

In the polycondensation reaction, the esterification reaction is first performed, and then the polycondensation reaction is performed.
In such an esterification reaction, a catalyst is used, and specifically, for example, a titanium-based catalyst such as tetraisopropyl titanate or tetrabutyl titanate, an antimony catalyst such as antimony trioxide, a germanium-based catalyst such as germanium dioxide, or the like. Examples thereof include catalysts and catalysts such as zinc acetate, manganese acetate, and dibutyltin oxide, and one or more of these are used. Among these, antimony trioxide, tetrabutyl titanate, germanium dioxide, and zinc acetate are preferable from the viewpoint of high catalytic activity and balance of hue.

The blending amount of the catalyst is preferably 1 to 10000 ppm, particularly preferably 10 to 5000 ppm, and further preferably 20 to 3000 ppm with respect to the total copolymerization component. If the blending amount is too small, the polymerization reaction tends to be difficult to proceed sufficiently, and if it is too large, there is no advantage such as shortening the reaction time and side reactions tend to occur.

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

After the above esterification reaction is carried out, a polycondensation reaction is carried out.
As the reaction conditions of the polycondensation reaction, the same catalyst as that used in the above esterification reaction is further blended in the same amount, and the reaction temperature is preferably 220 to 280 ° C, particularly preferably 230 to 270 ° C. It is preferable that the system is gradually depressurized and finally reacted at 5 hPa or less. If the reaction temperature is too low, the reaction tends to be difficult to proceed sufficiently, and if it is too high, side reactions such as decomposition tend to occur.

Thus, the polyester resin (A) used in the present invention can be obtained.

The polyester resin (A) usually has a structural unit derived from a polyvalent carboxylic acid (a1) and a structural unit derived from a polyol (a2), but is derived from the asymmetric aromatic dicarboxylic acid (a1-1-1). When the structural unit of is included as a structural unit derived from the polyvalent carboxylic acid (a1), the structural unit derived from the asymmetric aromatic dicarboxylic acid (a1-1-1) is derived from the polyvalent carboxylic acid (a1). The structural unit preferably contains 0.1 to 70 mol%, more preferably 0.5 to 60 mol%, still more preferably 1 to 50 mol%, particularly preferably 2 to 40 mol%, and particularly preferably. It is 3 to 30 mol%, most preferably 5 to 20 mol%.

When a structural unit derived from an aliphatic dicarboxylic acid having 4 or more carbon atoms (a1-2) is included as a structural unit derived from a polyvalent carboxylic acid (a1), the aliphatic dicarboxylic acid having 4 or more carbon atoms (a1) -2) The derived structural unit is preferably contained in the structural unit derived from the polyvalent carboxylic acid (a1) in an amount of 5 to 100 mol%, more preferably 20 to 99 mol%, still more preferably 40 to 98 mol%. , Particularly preferably 60 to 97 mol%, particularly preferably 80 to 95 mol%.

When the polyester resin (A) contains a structural unit derived from the hydrogenated polybutadiene structure-containing compound, the content of the structural unit derived from the hydrogenated polybutadiene structure-containing compound in the polyester resin (A) is 0. It is preferably 01 to 50% by weight, more preferably 0.1 to 30% by weight, still more preferably 0.2 to 20% by weight, particularly preferably 0.3 to 10% by weight, and particularly preferably 0. It is 4 to 5% by weight, most preferably 0.5 to 2% by weight.

The structural unit derived from the hydrogenated polybutadiene structure-containing compound in the polyester resin (A) may be contained as at least one of the structural unit derived from the polyvalent carboxylic acids (a1) and the structural unit derived from the polyol (a2). It is preferable from the viewpoint of adhesiveness to the polyolefin base material, and more preferably it is contained as a structural unit derived from the polyol (a2).

Further, when the structural unit derived from the hydrogenated polybutadiene polyol (a2-1) is included as the structural unit derived from the polyol (a2), the structure derived from the hydrogenated polybutadiene polyol (a2-1) is considered from the viewpoint of compatibility. The unit is preferably contained in the structural unit derived from the polyol (a2) in an amount of 0.001 to 15 mol%, more preferably 0.005 to 10 mol%, still more preferably 0.01 to 5 mol%, and particularly preferably. Is 0.05 to 2 mol%, particularly preferably 0.1 to 1 mol%.

On the other hand, when the structural unit derived from the branched structure-containing polyol (a2-2) is included as the structural unit derived from the polyol (a2), the branched structure-containing polyol breaks the crystallinity of the polyester resin (A). The structural unit derived from (a2-2) is preferably contained in the structural unit derived from the polyol (a2) in an amount of 5 to 100 mol%, more preferably 10 to 90 mol%, still more preferably 20 to 80 mol%. It is particularly preferably 30 to 70 mol%, and particularly preferably 40 to 60 mol%.

When the structural unit derived from the linear polyol (a2-3) is included as the structural unit derived from the polyol (a2), the structure derived from the linear polyol (a2-3) is derived from the viewpoint of stable resin formation. The unit is preferably contained in the structural unit derived from the polyol (a2) in an amount of 5 to 100 mol%, more preferably 10 to 90 mol%, still more preferably 20 to 80 mol%, and particularly preferably 30 to 60 mol%. Is.

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

The glass transition temperature of the polyester resin (A) is preferably −80 to 20 ° C., particularly preferably −75 to 10 ° C., still more preferably −70 to −20 ° C., more preferably −70 to −20 ° C. from the viewpoint of adhesive physical properties. Is −65 to −30 ° C., particularly preferably −60 to −35 ° C., and most preferably −55 to −40 ° C. If the glass transition temperature is too high, the flexibility is lost, the initial adhesiveness is lowered, the adhesive force is hard to be exhibited at a pressure of about finger pressure, and the workability tends to be lowered. If the glass transition temperature is too low, the cohesive force is lowered. However, the adhesive sheet is easily deformed and tends to spoil the appearance.

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

The ester bond concentration of the polyester resin (A) is preferably 3 to 9 mmol / g, more preferably 4 to 9 mmol / g, still more preferably 4.5 to 8.5 mmol / g, and particularly preferably 5 to 8 mmol / g. Is. If the ester bond concentration is too small, the polyester resin (A) tends to be soft and the adhesive properties tend to deteriorate. On the other hand, if the ester bond concentration is too high, the polyester resin (A) tends to become hard and the adhesive properties tend to deteriorate.

The ester bond concentration (mmol / g) is the number of moles of ester bonds in 1 g of the polyester resin, and is obtained by, for example, a calculated value from the charged amount. Such a calculation method is a value obtained by dividing the number of moles of the polyvalent carboxylic acids (a1) and the polyol (a2), whichever has the smaller amount, by the total weight, and an example of the calculation formula is shown below.
When the charged amounts of the polyvalent carboxylic acids (a1) and the polyol (a2) are the same molar amount, either of the following calculation formulas may be used.
Further, when a monomer having both a carboxy group and a hydroxyl group is used as the monomer, or when polyester is produced from caprolactone or the like, the calculation method is appropriately changed.

<When the number of polyvalent carboxylic acids (a1) is less than that of the polyol (a2)>
Ester bond concentration (mmol / g) = [(A1 / a1 × m1 + A2 / a2 × m2 + A3 / a3 × m3 ...) / Z] × 1000
A1, A2, A3 ...: Amount (g) of polyvalent carboxylic acids (a1) charged
a1, a2, a3 ...: Molecular weight of polyvalent carboxylic acids (a1) m1, m2, m3 ...: Number of carboxy groups per molecule of polyvalent carboxylic acids (a1)
Z: Finished weight (g)
<When the amount of polyol (a2) is less than that of carboxylic acids (a1)>
Ester bond concentration (mmol / g) = [(B1 / b1 × n1 + B2 / b2 × n2 + B3 / b3 × n3 ...) / Z] × 1000
B1, B2, B3 ...: Amount of polyol (a2) charged (g)
b1, b2, b3 ...: Molecular weight of polyol (a2) n1, n2, n3 ...: Number of hydroxyl groups per molecule of polyol (a2) Z: Finished weight (g)

Further, the ester bond 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) shall be ^{measured by 1} H-NMR measurement (proton type nuclear magnetic resonance spectroscopy measurement) and ¹³ C-NMR measurement (carbon type nuclear magnetic resonance spectroscopy measurement) at a resonance frequency of 400 MHz. Can be done.

It is preferable that the polyester resin (A) does not crystallize from the viewpoint of storage stability, but even when it crystallizes, it is preferable that the heat of fusion of the polyester resin (A) is as low as possible, and usually 35 J / g. Hereinafter, it is 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.
The heat of fusion for crystallization is a change in energy when a crystallized solid substance changes to a liquid state, and can be measured by a differential scanning calorimeter DSC.

The acid value of the police ether resin (A) is preferably 10 mgKOH / g or less, particularly preferably 3 mgKOH / g or less, more preferably 1.5 mgKOH / g or less, and further preferably 1 mgKOH / g or less. If the acid value is too high, hydrolysis tends to proceed and the cohesive force tends to decrease.

The hydroxyl value of the police ether resin (A) is preferably 50 mgKOH / g or less, particularly 30 mgKOH / g or less, further 20 mgKOH / g or less, and more preferably 15 mgKOH / g or less. If the hydroxyl value is too high, the cross-linking efficiency with the cross-linking agent (D) described later tends to decrease.

The acid value and hydroxyl value of the polyester resin (A) are determined by neutralization titration based on JIS K 0070.

The weight average molecular weight of the polyester resin (A) is preferably 5000 to 30000 from the viewpoint of the cohesive force of the pressure-sensitive adhesive, particularly 8000 to 20000, further 1000 to 120,000, and particularly 30000 to 100,000. Is preferable. If the weight average molecular weight is too small, sufficient cohesive force cannot be obtained as an adhesive, and heat resistance and mechanical strength tend to decrease. If the weight average molecular weight is too large, gelation tends to occur during the production of the polyester resin (A). , Resin tends to be difficult to obtain.

The number average molecular weight of the polyester resin (A) is preferably 3000 to 100,000, more preferably 4,000 to 800,000, further preferably 5,000 to 50,000, particularly preferably 6,000 to 30,000, and particularly preferably 7,000 to 20,000. Is. If the number average molecular weight is too small, sufficient cohesive force cannot be obtained as an adhesive, and heat resistance and mechanical strength tend to decrease, and if it is too large, adhesion to a substrate tends to decrease.

The weight average molecular weight and the number average molecular weight of the present invention are based on the standard polystyrene molecular weight conversion, and are shown on a high-speed liquid chromatograph (manufactured by Tosoh Corporation, "HLC-8320GPC") in a column: TSKgel SuperMultipore HZ-M (exclusion limit). It is measured by using two molecular weights (2 × 10 ⁶ , theoretical plate number: 16000 stages / piece, filler material: styrene-divinylbenzene copolymer, filler particle size: 4 μm) in series.

<Petroleum resin adhesive (B)>
The polyester-based pressure-sensitive adhesive composition of the present invention contains the polyester-based resin (A) and a petroleum resin-based pressure-sensitive adhesive (B) having a specific number average molecular weight. As described above, the petroleum resin-based pressure-sensitive adhesive has a low polarity and is inferior in compatibility with a highly polar polyester-based resin. Therefore, it is generally difficult to mix and use these. Moreover, it is even more so when trying to improve the tackiness. However, in the case where the polyester resin (A) is used as the base resin, the present invention specifically contains the polyester resin (A) and the petroleum resin pressure-sensitive adhesive (B) having a specific number average molecular weight. It has been found that a polyester-based pressure-sensitive adhesive composition having excellent adhesive strength, holding power and tackiness can be obtained by blending in a ratio.

The number average molecular weight of the petroleum resin-based pressure-sensitive adhesive (B) is 400 to 8000. It is preferably 500 to 5000, more preferably 600 to 3000, particularly preferably 700 to 2000, and particularly preferably 750 to 1500. When the number average molecular weight of the petroleum resin-based pressure-sensitive adhesive (B) is within the above range, the adhesive strength, holding power and tackiness are excellent. The number average molecular weight of the petroleum resin-based pressure-sensitive adhesive (B) can be measured by the same method as that of the polyester-based resin (A) described above.

The weight average molecular weight of the petroleum resin-based pressure-sensitive adhesive (B) is preferably 400 to 10000, particularly preferably 600 to 8000, further 800 to 4000, and particularly preferably 1000 to 2000. When the weight average molecular weight of the petroleum resin-based pressure-sensitive adhesive (B) is within the above range, the adhesive strength, holding power and tackiness are excellent. The weight average molecular weight of the petroleum resin-based pressure-sensitive adhesive (B) can be measured by the same method as that of the polyester-based resin (A) described above.

Examples of the petroleum resin-based tackifier (B) include an aliphatic (C5 series) petroleum resin, an aromatic (C9 series) petroleum resin, and an aliphatic / aromatic copolymer (C5 / C9 series) petroleum. Examples thereof include resins, hydrogenated petroleum resins obtained by hydrogenating them, aliphatic petroleum resins such as dicyclopentadiene, and kumaron-inden resins. These may be used alone or in combination of two or more.

Among the petroleum resin-based tackifiers (B), it is preferable to have an aromatic ring structure from the viewpoint of excellent adhesive strength, holding power and tackiness, and further, aromatic (C9-based) petroleum resin and aliphatic. / Aromatic copolymer (C5 / C9 series) petroleum resin is preferable, and aliphatic / aromatic copolymer (C5 / C9 series) petroleum resin is particularly preferable. Among them, it is preferable that the aromatic ring structure is derived from a styrene resin.

The styrene-based resin is preferably a styrene-based polymer, but may be a mixture of a styrene-based monomer and a styrene-based polymer. Further, the styrene-based polymer may be a homopolymer or a copolymer of one or more kinds of styrene-based monomers, or a copolymer of one or more kinds of styrene-based monomers and a monomer other than the styrene-based monomer. It may be.

Examples of the styrene-based polymer include polystyrene, poly-α-methylstyrene, a copolymer of α-methylstyrene and styrene, a copolymer of a styrene-based monomer and an aliphatic monomer, and a styrene-based monomer and an aromatic monomer. Examples thereof include a polymer of α-methylstyrene and a polymer of a styrene-based monomer other than α-methylstyrene. Among them, a copolymer of a styrene-based monomer and a copolymer of a styrene-based monomer and an aliphatic monomer are preferable from the viewpoint of excellent adhesive strength, holding power, and tackiness.

Examples of the styrene-based monomer include alkyl-substituted styrenes such as styrene, 2-methylstyrene, 4-methylstyrene, 4-ethylstyrene, 4-t-butylstyrene, and 2,4-dimethylstyrene, α-methylstyrene, and the like. Examples thereof include α-alkyl substituted styrene such as α-methyl-4-methylstyrene, substituted styrene such as 2-chlorostyrene, 4-chlorostyrene, hydroxystyrene, and vinylbenzoic acid.

Examples of the monomer other than the styrene-based monomer include an aliphatic monomer and an aromatic monomer.
Examples of the aliphatic monomer include aliphatic hydrocarbons.
Examples of the aromatic monomer include aromatic hydrocarbons other than those exemplified by the styrene-based monomer.

Examples of commercially available products of the copolymer of the styrene-based monomer and the aliphatic monomer include "FTR6100", "FTR6110", and "FTR6125" manufactured by Mitsui Chemicals, Inc.

Examples of commercially available products of the copolymer of the styrene-based monomer include "FTR2120", "FTR2140", "FTR8100", and "FTR8120" manufactured by Mitsui Chemicals, Inc.

The softening point (for example, measured by the ring-and-ball method) of the petroleum resin-based pressure-sensitive adhesive (B) is preferably 30 to 200 ° C., particularly preferably 60 to 180 ° C., and more preferably 70 ° C. It is ~ 160 ° C., more preferably 80 to 140 ° C., and particularly preferably 90 to 130 ° C. When the softening point is within the above range, the adhesive strength, holding power and tackiness tend to be excellent.

The petroleum resin-based pressure-sensitive adhesive (B) preferably has an acid value of 5 mgKOH / g or less, particularly 3 mgKOH / g or less, further 2 mgKOH / g or less, and particularly 1 mgKOH / g or less. Is preferable. When a plurality of types of tackifier resins are used in combination, the average thereof is preferably in the above range.

The petroleum resin-based pressure-sensitive adhesive (B) preferably has a hydroxyl value of 5 mgKOH / g or less, particularly 3 mgKOH / g or less, further 2 mgKOH / g or less, and particularly 1 mgKOH / g or less. It is preferable to have. When a plurality of types of tackifier resins are used in combination, the average thereof is preferably in the above range.

The acid value and hydroxyl value of the petroleum resin-based tackifier (B) are determined by neutralization titration based on JIS K 0070.

The content of the petroleum resin-based tackifier (B) is 0.01 to 50 parts by weight, more preferably 1 to 40 parts by weight, still more preferably, with respect to 100 parts by weight of the polyester resin (A). Is 2 to 30 parts by weight, particularly preferably 3 to 25 parts by weight, particularly preferably 4 to 20 parts by weight, and most preferably 5 to 15 parts by weight. When the content is within the above range, the adhesive strength, holding power and tackiness are excellent.

In the polyester-based pressure-sensitive adhesive composition of the present invention, along with the polyester-based resin (A) and the petroleum resin-based pressure-sensitive adhesive (B), a hydrolysis inhibitor (C), a cross-linking agent (D), and a urethanization are preferable. The catalyst (E) and, if necessary, an antioxidant and the like may be contained.

<Hydrolyzant (C)>
The hydrolysis inhibitor (C) is contained to ensure the long-term durability of the polyester-based pressure-sensitive adhesive composition.
As the hydrolysis inhibitor (C), conventionally known ones can be used, and examples thereof include a compound that reacts with and binds to the carboxy group terminal of the polyester resin (A). For example, a compound containing a functional group such as a carbodiimide group, an epoxy group, an oxazoline group, and the like can be mentioned. Among these, the carbodiimide group-containing compound is preferable because it has a high effect of eliminating the catalytic activity of the proton derived from the carboxy group terminal.

As the carbodiimide group-containing compound, a known carbodiimide having one or more carbodiimide groups (-N = C = N-) in the molecule may be usually used, but the point of improving durability under higher temperature and humidity. It is preferable that the compound contains two or more carbodiimide groups in the molecule, that is, a polyvalent carbodiimide-based compound, in particular, three or more carbodiimide groups in the molecule, further five or more, particularly seven or more. It is preferably a compound contained. The number of carbodiimide groups in the molecule is usually 50 or less, and 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 decarboxylating and condensing diisocyanate in the presence of a carbodiimidization catalyst.

Further, as the high molecular weight polycarbodiimide, one in which the terminal isocyanate group is sealed with a sealing agent is preferable from the viewpoint of storage stability. Examples of the encapsulant include a compound having an active hydrogen that reacts with an isocyanate group and a compound having an isocyanate group. For example, monoalcohols, monocarboxylic acids, monoamines, monoisocyanates and the like having one substituent selected from a carboxy group, an amino group and an isocyanate group can be mentioned.

Examples of such high molecular weight polycarbodiimides include those obtained by decarboxylating and condensing the following diisocyanates.

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

Examples of commercially available products of the carbodiimide group-containing compound include the carbodilite (registered trademark) series manufactured by Nisshinbo Chemical Co., Ltd., among which carbodilite (registered trademark) V-01, V-02B, V-03, V-04K, V-04PF, V-05, V-07, V-09, and V-09GB are preferable because they have excellent compatibility with the polyester resin (A).

As the epoxy group-containing compound, for example, a glycidyl ester compound, a glycidyl ether compound, or the like is preferable.

Specific examples of the above glycidyl ester compound include benzoic acid glycidyl ester, t-Bu-benzoic acid glycidyl ester, p-toluic acid glycidyl ester, cyclohexanecarboxylic acid glycidyl ester, pelargonic acid glycidyl ester, stearic acid glycidyl ester, and laurin. Acid glycidyl ester, palmitate glycidyl ester, behenic acid glycidyl ester, versatic acid glycidyl ester, oleate glycidyl ester, linoleic acid glycidyl ester, linolenic acid glycidyl ester, behenolic acid glycidyl ester, stearolic acid glycidyl ester, terephthalic acid diglycidyl ester , Isophthalic acid diglycidyl ester, phthalic acid diglycidyl ester, naphthalenedicarboxylic acid diglycidyl ester, methylterephthalic acid diglycidyl ester, hexahydrophthalic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester, cyclohexanedicarboxylic acid diglycidyl ester, adipine Examples thereof include acid diglycidyl ester, succinic acid diglycidyl ester, sebacic acid diglycidyl ester, dodecandioic acid diglycidyl ester, octadecanedicarboxylic acid diglycidyl ester, trimellitic acid triglycidyl ester, pyromellitic acid tetraglycidyl ester, and the like. Can be used alone or in combination of two or more.

Specific examples of the glycidyl ether compound include phenylglycidyl ethane, o-phenyl glycidyl ethane, 1,4-bis (β, γ-epoxypropoxy) butane, and 1,6-bis (β, γ). -Epoxy propoxy) hexane, 1,4-bis (β, γ-epoxy propoxy) benzene, 1- (β, γ-epoxy propoxy) -2-ethoxyethane, 1- (β, γ-epoxy propoxy) -2- Benzeneoxyethane, 2,2-bis- [р- (β, γ-epoxypropoxy) phenyl] propane and 2,2-bis- (4-hydroxyphenyl) propane and 2,2-bis- (4-hydroxyphenyl) ) Examples thereof include bisglycidyl polyether obtained by the reaction of bisphenol such as methane and epichlorohydrin, and these can be used alone or in combination of two or more.

As the oxazoline group-containing compound, a bisoxazoline compound or the like is 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 (4,5'-diethyl-2-oxazoline), 2,2'-bis (4-propyl-2) -Oxazoline), 2,2'-bis (4-butyl-2-oxazoline), 2,2'-bis (4-hexyl-2-oxazoline), 2,2'-bis (4-phenyl-2-oxazoline) ), 2,2'-bis (4-cyclohexyl-2-oxazoline), 2,2'-bis (4-benzyl-2-oxazoline), 2,2'-p-phenylenebis (2-oxazoline), 2 , 2'-m-phenylenebis (2-oxazoline), 2,2'-o-phenylenebis (2-oxazoline), 2,2'-p-phenylenebis (4-methyl-2-oxazoline), 2, 2'-p-phenylenebis (4,4-dimethyl-2-oxazoline), 2,2'-m-phenylenebis (4-methyl-2-oxazoline), 2,2'-m-phenylenebis (4, 4-Dimethyl-2-oxazoline), 2,2'-ethylenebis (2-oxazoline), 2,2'-tetramethylenebis (2-oxazoline), 2,2'-hexamethylenebis (2-oxazoline), 2,2'-octamethylenebis (2-oxazoline), 2,2'-decamethylenebis (2-oxazoline), 2,2'-ethylenebis (4-methyl-2-oxazoline), 2,2'- Tetramethylenebis (4,4-dimethyl-2-oxazoline), 2,2'-9,9'-diphenoxyetambis (2-oxazoline), 2,2'-cyclohexylenebis (2-oxazoline), 2 , 2'-Diphenylene bis (2-oxazoline) and the like can be exemplified, and among these, 2,2'-bis (2-oxazoline) is from the viewpoint of reactivity with the polyester resin (A). Most preferred from. In addition, these can be used alone or in combination of two or more.

As these hydrolysis inhibitors (C), those having low volatility are preferable, and those having a high number average molecular weight are preferably used, and are usually 300 to 10000, preferably 1000 to 5000.
Further, as the hydrolysis inhibitor (C), it is preferable to use one having a high weight average molecular weight from the viewpoint of hydrolysis resistance. The weight average molecular weight of the hydrolysis inhibitor (C) is preferably 500 or more, more preferably 1000 or more, further preferably 2000 or more, and particularly preferably 3000 or more. The upper limit of the weight average molecular weight is usually 50,000.
If the molecular weight of the hydrolysis inhibitor (C) is too small, the hydrolysis resistance tends to decrease. If the molecular weight is too large, the compatibility with the polyester resin (A) tends to decrease.

Among the hydrolysis inhibitors (C), it is preferable to use a carbodiimide group-containing compound, and the carbodiimide equivalent at that time is preferably 50 to 10000, particularly 100 to 1000, and further 150 to 500. Is preferable. The carbodiimide equivalent indicates the chemical formula amount per carbodiimide group.

The content of the hydrolysis inhibitor (C) is preferably 0.01 to 10 parts by weight, particularly preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the polyester resin (A). , More preferably 0.2 to 3 parts by weight. If the content is too large, turbidity tends to occur due to poor compatibility with the polyester resin (A), and if it is too small, sufficient durability tends to be difficult to obtain.

Further, the content of the hydrolysis inhibitor (C) is preferably optimized according to the acid value of the polyester resin (A), and the polyester resin in the polyester pressure-sensitive adhesive composition. The molar ratio of the total number of moles (y) of the functional groups of the hydrolysis inhibitor (C) in the polyester-based pressure-sensitive adhesive composition to the total number of moles (x) of the acidic functional groups (A) [(y) / ( x)] is preferably 0.5 ≦ (y) / (x), particularly preferably 1 ≦ (y) / (x) ≦ 1000, and even more preferably 1.5 ≦ (y) / (x). ) ≤ 100.
If the molar ratio of (y) to (x) is too low, the moist 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 force, and durability performance tend to decrease.

<Crosslinking agent (D)>
The polyester-based pressure-sensitive adhesive composition of the present invention preferably further contains a cross-linking agent (D), and by containing the cross-linking agent (D), the polyester-based resin (A) is cross-linked with the cross-linking agent (D). The cohesive force is excellent, and the performance as an adhesive can be improved.

Examples of the cross-linking agent (D) include compounds having a functional group that reacts with at least one of a hydroxyl group and a carboxy group contained in the polyester resin (A), such as a polyisocyanate compound and a polyepoxy compound. Among these, it is particularly preferable to use a polyisocyanate compound from the viewpoint of achieving both initial adhesiveness, mechanical strength, and heat resistance in a well-balanced manner.

Examples of such polyisocyanate compounds include tolylene diisocyanate compounds such as 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, xylylene diisocyanate compounds such as 1,3-xylylene diisocyanate, and diphenylmethane-. Diphenylmethane-based compounds such as 4,4-diisocyanate, aromatic isocyanate-based compounds such as naphthalene diisocyanate compounds such as 1,5-naphthalenediocyanate; isophorone diisocyanate, 1,4-cyclohexanediisocyanate, 4,4'-dicyclohexylmethane diisocyanate , Methylcyclohexanediisocyanate, isopropyridendicyclohexyl-4,4'-diisocyanate, 1,3-diisocyanatomethylcyclohexane, norbornandiisocyanate and other alicyclic isocyanate compounds; Examples thereof include isocyanate-based compounds; and adducts, bullets, and isocyanurates of the above-mentioned isocyanate-based compounds. The polyisocyanate compound may be used even if the isocyanate portion is blocked with phenol, lactam or the like. One of these polyisocyanate compounds may be used alone, or two or more thereof may be mixed and used.

The content of the cross-linking agent (D) can be appropriately selected depending on the molecular weight of the polyester-based resin (A) and the purpose of use, but is usually one equivalent of at least one of the hydroxyl group and the carboxy group contained in the polyester-based resin (A). On the other hand, the reactive group contained in the cross-linking agent (D) preferably contains the cross-linking agent (D) in a proportion of 0.2 to 10 equivalents, particularly preferably 0.5 to 5 equivalents, and further. It is preferably 0.5 to 3 equivalents, more preferably 0.5 to 1.5 equivalents.
If the equivalent number of the reactive groups contained in the cross-linking agent (D) is too small, the cohesive force tends to decrease, and if it is too large, the flexibility tends to decrease.

The content of the cross-linking agent (D) is preferably 0.1 to 20 parts by weight with respect to 100 parts by weight of the polyester resin (A), and is particularly preferable. It is 0.2 to 15 parts by weight, more preferably 0.3 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, and particularly preferably 1 to 3 parts by weight.
If the content of the cross-linking agent (D) is too small, the cohesive force tends to decrease, and if it is too large, the flexibility tends to decrease.

Further, in the reaction between the polyester resin (A) and the cross-linking agent (D), an organic solvent having no functional group that reacts with these components (A) and (D), for example, esters such as ethyl acetate and butyl acetate , Ketones such as methyl ethyl ketone and methyl isobutyl ketone, and organic solvents such as aromatics such as toluene and xylene can be used. These can be used alone or in combination of two or more.

<Urethane catalyst (E)>
The polyester-based pressure-sensitive adhesive composition of the present invention more preferably contains a urethanization catalyst (E) from the viewpoint of reaction rate.

Examples of the urethanization catalyst (E) include organometallic compounds and tertiary amine compounds. These can be used alone or in combination of two or more.

Examples of the organic metal compound include zirconium compounds, iron compounds, tin compounds, titanium compounds, lead compounds, cobalt compounds, zinc compounds and the like.
Examples of the zirconium-based compound include zirconium naphthenate, zirconium acetylacetonate and the like.
Examples of the iron-based compound include iron acetylacetonate and iron 2-ethylhexanoate.
Examples of the tin compound include dibutyltin dichloride, dibutyltin oxide, dibutyltin dilaurate and the like.
Examples of the titanium-based compound include dibutyl titanium dichloride, tetrabutyl titanate, butoxytitanium trichloride and the like.
Examples of the lead-based compound include lead oleate, lead 2-ethylhexanoate, lead benzoate, lead naphthenate and the like.
Examples of the cobalt-based compound include cobalt 2-ethylhexanoate and cobalt benzoate.
Examples of the zinc-based compound include zinc naphthenate, zinc 2-ethylhexanoate and the like.

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

Among these urethanization catalysts (E), organometallic compounds are preferable, and zirconium compounds are particularly preferable, in terms of reaction rate and pot life of the pressure-sensitive adhesive layer. Further, it is preferable that acetylacetone is used in combination with the urethanization catalyst (E) as a catalytic action inhibitor. The inclusion of acetylacetone is preferable in that the catalytic action at low temperature is suppressed and the pot life is extended.

In the polyester-based pressure-sensitive adhesive composition of the present invention, the above-mentioned polyester-based resin (A), petroleum resin-based pressure-sensitive adhesive (B), hydrolysis inhibitor (C), cross-linking agent (D), and urethanization catalyst ( In addition to E), antioxidants such as hindered phenols, softeners, ultraviolet absorbers, stabilizers, antistatic agents, and petroleum resin adhesives (B), as long as the effects of the present invention are not impaired. ), Etc., and other additives such as inorganic or organic fillers, metal powders, pigments, and other powders and particles can be blended. These can be used alone or in combination of two or more.

The polyester-based pressure-sensitive adhesive according to the present invention is obtained by cross-linking the polyester-based pressure-sensitive adhesive composition.

The pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer containing the polyester-based pressure-sensitive adhesive, and the pressure-sensitive adhesive layer is preferably formed on one side or both sides of a supporting base material.
In the present invention, the term "sheet" is described as including "film" and "tape".

<Adhesive sheet>
The adhesive sheet can be produced, for example, as follows.
As a method for producing such an adhesive sheet, it can be produced according to a known general method for producing an adhesive sheet. For example, the polyester-based pressure-sensitive adhesive composition is applied onto a base material, dried, and the pressure-sensitive adhesive on the opposite side is applied. A release sheet is attached to the layer surface and cured if necessary to have a base material and a pressure-sensitive adhesive layer containing a polyester-based pressure-sensitive adhesive, and the pressure-sensitive adhesive layer is provided on at least one surface of the base material. The adhesive sheet of the present invention can be obtained.

The pressure-sensitive adhesive sheet of the present invention can also be obtained by applying the polyester-based pressure-sensitive adhesive composition on a release sheet, drying it, attaching a base material to the pressure-sensitive adhesive layer surface on the opposite side, and curing it if necessary. ..

Further, a base material having a pressure-sensitive adhesive layer containing a polyester-based pressure-sensitive adhesive and having no base material by forming a pressure-sensitive adhesive layer on the release sheet and attaching the release-type sheet to the surface of the pressure-sensitive adhesive layer on the opposite side. It is possible to manufacture a less type adhesive sheet.

When the obtained adhesive sheet or base material-less type adhesive sheet is used, the release sheet is peeled off from the adhesive layer and the adhesive layer and the adherend are attached to each other.

Examples of the base material include polyester resins such as polyethylene naphthalate, polyethylene terephthalate, ribobutylene terephthalate, and polyethylene terephthalate / isophthalate copolymers; polyolefin resins such as polyethylene, polypropylene, and polymethylpentene; Polyfluorinated ethylene resins such as vinylidene polyfluoride and ethylene polyfluoride; polyamides such as nylon 6, nylon 6 and 6; polyvinyl chloride, polyvinyl chloride / vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl Alcohol copolymers, vinyl polymers such as polyvinyl alcohol and vinylon; cellulose resins such as cellulose triacetate and cellophane; acrylic resins such as methyl polymethacrylate, ethyl polymethacrylate, ethyl polyacrylate and butyl polyacrylate. Polystyrene; Polycarbonate; Polyallylate; Polyimide; Sheet made of at least one synthetic resin selected from the group consisting of cycloolefin polymers, etc .; Metal foils of aluminum, copper, iron; Paper such as high-quality paper, glassin paper; Glass; Examples thereof include woven fabrics and non-woven fabrics made of fibers, natural fibers, synthetic fibers and the like. These base materials can be used as a single layer or as a multi-layer in which two or more kinds are laminated.

Among these, polyethylene terephthalate and a base material made of polyimide are particularly preferable, and polyethylene terephthalate is particularly preferable because it is excellent in adhesiveness to an adhesive.

Further, as the base material, a foam base material, for example, a foam sheet made of a foam of a synthetic resin such as polyurethane foam, polyethylene foam, or polyacrylate foam can be used. Among these, polyethylene foam and polyacrylate foam are preferable from the viewpoint of excellent balance of followability to the adherend and adhesive strength.

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

As the release sheet, for example, a sheet, paper, cloth, non-woven fabric or the like made of various synthetic resins exemplified in the above-mentioned base material can be used after being released. As the release sheet, it is preferable to use a silicone-based release sheet.

As a method for applying the polyester-based pressure-sensitive adhesive composition, for example, a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, a spray coater, a comma coater or the like may be used.

As the conditions of the 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, 23 ° C. for 1 to 20 days, preferably 23 ° C. It may be carried out under conditions such as 3 to 14 days and 1 to 10 days at 40 ° C.

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.

The thickness of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet and the base-less double-sided pressure-sensitive 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 the adhesive layer is too thin, the adhesive strength tends to decrease, and if it is too thick, it becomes difficult to apply the adhesive layer uniformly, and problems such as bubbles entering the coating film tend to occur. be. When considering shock absorption, it is preferably 50 μm or more.

The thickness of the pressure-sensitive adhesive layer is obtained by subtracting the measured value of the thickness of the constituent members other than the pressure-sensitive adhesive layer from the measured value of the thickness of the entire pressure-sensitive adhesive sheet using "ID-C112B" manufactured by Mitutoyo. ..

The gel fraction of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is preferably 5% by weight or more, particularly preferably 6 to 80% by weight, still more preferably 7 to 60% by weight, from the viewpoint of durability and adhesive strength. It is more preferably 10 to 40% by weight, particularly preferably 15 to 35% by weight, and most preferably 20 to 30% by weight. If the gel fraction is too low, the cohesive force tends to decrease and the holding force tends to decrease. If the gel fraction is too high, the cohesive force tends to increase and the adhesive force tends to decrease.

The gel fraction is a measure of the degree of cross-linking, and is calculated by, for example, the following method. That is, a pressure-sensitive adhesive sheet (without a release sheet) in which a pressure-sensitive adhesive layer is formed on a polymer sheet (for example, PET film or the like) as a base material is wrapped with a 200-mesh SUS wire mesh and contained in toluene. The gel fraction is defined as the weight percentage of the insoluble adhesive component remaining in the wire mesh after immersion with respect to the weight of the pressure-sensitive adhesive component before immersion at 23 ° C. for 24 hours. However, the weight of the base material is deducted.

Further, the pressure-sensitive adhesive sheet may be protected by providing a release sheet on the outside of the pressure-sensitive adhesive layer, if necessary. Further, in the pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive layer is formed on one side of the base material, the pressure-sensitive adhesive layer is utilized by performing a peeling treatment on the surface of the base material opposite to the pressure-sensitive adhesive layer. It is also possible to protect.

The polyester-based adhesive of the present invention can be used for bonding various members, and in particular, for single-sided or double-sided adhesive sheets used for bonding optical members, for fixing members of portable electronic devices, and for fixing electronic members. Used for single-sided or double-sided adhesive sheets.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded. In the example, "part" and "%" mean the weight standard unless otherwise specified.
The glass transition temperature, number average molecular weight, weight average molecular weight, acid value, hydroxyl value, ester bond concentration, and heat of fusion of the polyester resin (A) in the following examples were determined according to the above-mentioned methods.

Prior to the examples, each component was prepared as follows.

[Manufacturing of polyester resin]
The molar% of the structural unit ratio derived from the finished component of the polyvalent carboxylic acid described in the following production example (hereinafter, may be abbreviated as “finished component ratio”) is 100 mol% of the total amount of the polyvalent carboxylic acid. The molar ratio is shown.
Further, the mol% of the finished component ratio of the polyol described in the following production example indicates the molar ratio when the total amount of the polyol is 100 mol%.

[Polyester resin (A-1)]
94.6 parts of isophthalic acid (IPA) (a1-1-1) as polyvalent carboxylic acids (a1) in a reaction can equipped with a heating device, thermometer, stirrer, rectification tower, nitrogen introduction tube and vacuum device. (20 mol%) and 460.8 parts (80 mol%) of sebacic acid (SebA), 1,4-butanediol (1.4BG) (a2-3) 128.3 parts (50 mol%) as polyol (a2) ), Neopentyl glycol (NPG) (a2-2) 296.6 parts (100 mol%), trimethylolpropane (TMP) 5.7 parts (1.5 mol%), and hydrogenated polybutadiene polyol (a2-1). ) (Nippon Soda Co., Ltd., "GI-1000") 14 parts (0.3 mol%), 0.05 parts of zinc acetate as a catalyst, gradually raise the temperature to 250 ° C, and ester over 4 hours. A chemical reaction was carried out. Then, the internal temperature was raised to 260 ° C., 0.05 part of tetrabutyl titanate was charged as a catalyst, the pressure was reduced to 1.33 hPa, and the polymerization reaction was carried out over 3 hours to produce a polyester resin (A-1).
The finished component ratio of the obtained polyester resin (A-1) was isophthalic acid / sebacic acid = 20 mol% / 80 mol% as the polyvalent carboxylic acids (a1) and 1,4-butanediol as the polyol (a2). / Neopentyl glycol / Trimethylolpropane / Hydrogenated polybutadiene polyol = 33.7 mol% / 64.5 mol% / 1.5 mol% / 0.3 mol%, and various physical properties are as shown in Table 1. ..
The content of the structural unit derived from the hydrogenated polybutadiene structure-containing compound in the polyester resin (A-1) was 1.7% by weight, and the heat of fusion of the crystals was 0 J / g.

[Adhesives (B), (B')]
(B-1): Copolymer of styrene-based monomer and aliphatic monomer (number average molecular weight (Mn) 860, weight average molecular weight (Mw) 1210, glass transition temperature (Tg) 30 ° C., softening point 95 ° C., acid Valuation less than 1 mgKOH / g, hydroxyl value less than 1 mgKOH / g (manufactured by Mitsui Chemicals, "FTR-6100")
(B-2): Copolymer of styrene-based monomer and aliphatic monomer (number average molecular weight (Mn) 1150, weight average molecular weight (Mw) 1950, glass transition temperature (Tg) 65 ° C., softening point 125 ° C., acid Valuation less than 1 mgKOH / g, hydroxyl value less than 1 mgKOH / g (manufactured by Mitsui Chemicals, "FTR-6125")
(B-3): Copolymer of styrene-based monomer (number average molecular weight (Mn) 820, weight average molecular weight (Mw) 1240, glass transition temperature (Tg) 35 ° C., softening point 100 ° C., acid value less than 1 mgKOH / g , Hydroxyl value less than 1 mgKOH / g (manufactured by Mitsui Chemicals, "FTR-8100")
(B'-1): Terpene phenol-based tackifier (number average molecular weight (Mn) 500, softening point 80 ° C., acid value less than 1 mgKOH / g, hydroxyl value 70 mgKOH / g (manufactured by Yasuhara Chemical Co., Ltd., "T80")
(B'-2): aliphatic monomer copolymer (number average molecular weight (Mn) 370, weight average molecular weight (Mw) 500, glass transition temperature (Tg) -31 ° C, softening point 10 ° C, acid value 1 mgKOH / Less than g, hydroxyl value less than 1 mgKOH / g (manufactured by Clay Valley, "Wingtack 10")

[Hydrolyzant (C)]
(C-1): Multivalent carbodiimide compound (manufactured by Nisshinbo Chemical Co., Ltd., "Carbodilite V-09GB, solid content concentration 70%")

[Crosslinking agent (D)]
(D-1): Trimethylolpropane / tolylene diisocyanate adduct (manufactured by Tosoh Corporation, "Coronate L55E, solid content concentration 55%")

[Urethane catalyst (E)]
(E-1): Zirconium-based compound diluted with acetylacetone to a solid content concentration of 1% (manufactured by Matsumoto Fine Chemicals, "Organix ZC-150")

(Examples 1 to 4, Comparative Examples 1 to 6)
The polyester resin (A) obtained above is diluted with ethyl acetate to a solid content concentration of 50%, and the pressure-sensitive adhesive (B) or (B) is applied to the polyester resin (A) (100 parts as a solid content). '), Hydrolysis inhibitor (C), cross-linking agent (D), and urethanization catalyst (E) are blended (solid content ratio) as shown in Table 2, and the mixture is stirred and mixed to make a polyester-based material. A pressure-sensitive adhesive composition was obtained.
Using the polyester-based pressure-sensitive adhesive compositions obtained in the above Examples and Comparative Examples, a pressure-sensitive adhesive sheet was prepared as follows and evaluated as follows. Moreover, the gel fraction of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet was determined according to the above-mentioned method.

<Making an adhesive sheet with a single-sided release film>
The polyester-based pressure-sensitive adhesive compositions obtained in Examples and Comparative Examples were applied onto a PET film having a thickness of 38 μm (“Lumilar T60” manufactured by Toray Industries, Inc.) using an applicator, dried at 100 ° C. for 3 minutes, and dried. A pressure-sensitive adhesive sheet with a PET film having a thickness of the pressure-sensitive adhesive layer of 25 μm was obtained.
Next, the surface of the pressure-sensitive adhesive layer of the obtained pressure-sensitive adhesive sheet with PET film was covered with a release film made of PET (manufactured by Mitsui Chemicals Tohcello Co., Ltd., SP-PET-01-BU) having a thickness of 38 μm, and aged at 40 ° C. for 4 days. Then, an adhesive sheet with a single-sided release film was obtained.

(Adhesive sheet evaluation)
[Adhesive force]
The pressure-sensitive adhesive sheet with a single-sided release film obtained above was cut to a size of 25 mm × 200 mm in an environment of 23 ° C. and 50% RH, and then the release film was peeled off to remove the pressure-sensitive adhesive layer side (1). Mirror-finished stainless steel plate (SUS-BA plate), (2) PET film lined with SUS-BA plate (3) Polyethylene plate (PE), each of which is pressure-bonded by reciprocating a 2 kg roller twice, under the same atmosphere. After allowing to stand for 30 minutes, the peel strength (N / 25 mm) of 180 degrees was measured at a peeling speed of 300 mm / min using an autograph (“Autograph AG-X 50N” manufactured by Shimadzu Corporation). The evaluation criteria are as follows.
(Evaluation criteria)
○ ・ ・ ・ Larger than 10N / 25mm Δ ・ ・ ・ Larger than 5N / 25mm and 10N / 25mm or less × ・ ・ ・ 5N / 25mm or less

[Holding power]
The adhesive sheet with a single-sided release film obtained above is cut to a size of 25 mm × 50 mm in an environment of 23 ° C. and 50% RH, the release film is peeled off, and a 2 kg roller is placed on a stainless steel plate (SUS304). Pressurize and apply 2 times (pasting area 25 mm x 25 mm), and use a creep tester (manufactured by Tester Sangyo Co., Ltd., holding force tester BE-501 with high temperature and humidity chamber) to apply a load of 1 kg in an atmosphere of 40 ° C for 24 hours. The holding force was measured. The evaluation criteria are as follows.
(Evaluation criteria)
〇 ・ ・ ・ No deviation △ ・ ・ ・ The deviation is 1.0 mm or less × ・ ・ ・ The deviation is larger than 1.0 mm or falls

[Tackiness]
The adhesive sheet with a single-sided release film obtained above was cut into a size of 25 mm × 100 mm in an environment of 23 ° C. and 50% RH, and installed at an angle of 30 ° using an inclined ball tack tester. After that, the release film was peeled off, 32 types of bearing balls with a diameter of 1/32 to 1 inch were rolled at a sliding distance of 100 mm, and the maximum number of balls that remained on the adhesive surface for 30 seconds or more. Was used as the ball tack value. The evaluation criteria are as follows.
(Evaluation criteria)
〇 ・ ・ ・ Ball No. 9 or more △ ・ ・ ・ Ball No. 7-8
× ・ ・ ・ Ball No. 6 or less

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From the results in Table 2 above, the polyester-based adhesives of Examples 1 to 4 in which the polyester-based resin (A) and the petroleum resin-based adhesive resin (B) having a specific number average molecular weight were used in a specific content ratio. It can be seen that the pressure-sensitive adhesive sheet obtained from the agent composition is excellent in all of adhesive strength, holding power, and tackiness.
On the other hand, the pressure-sensitive adhesive sheet obtained from the polyester-based pressure-sensitive adhesive composition of Comparative Example 1 which does not use the petroleum resin-based pressure-sensitive adhesive resin (B) having a specific number average molecular weight has a holding power, but has a sticking power. The tackiness was inferior. Further, the pressure-sensitive adhesive sheet obtained from the polyester-based pressure-sensitive adhesive composition of Comparative Example 2 using a large content of the petroleum resin-based pressure-sensitive adhesive resin (B) having a specific number average molecular weight has adhesive strength, holding power, and ball tack. It was inferior to all. The pressure-sensitive adhesive sheets obtained from the polyester-based pressure-sensitive adhesive compositions of Comparative Examples 3 and 4 using the terpene-based pressure-sensitive adhesive resin had a holding power, but were inferior in adhesive strength and tackiness. Further, the pressure-sensitive adhesive sheets obtained from the polyester-based pressure-sensitive adhesive compositions of Comparative Examples 5 to 6 using the petroleum resin-based pressure-sensitive adhesive resin having a small number average molecular weight are excellent in holding power but inferior in adhesive strength and tackiness. Met. From this, the polyester-based pressure-sensitive adhesive composition containing the polyester-based resin (A) and the petroleum resin-based pressure-sensitive adhesive resin (B) having a specific number average molecular weight in a specific ratio has adhesive properties. It turns out to be excellent.

The polyester-based pressure-sensitive adhesive composition of the present invention is excellent in adhesive strength, holding power, and tackiness. Therefore, the polyester-based pressure-sensitive adhesive and the pressure-sensitive adhesive sheet using the polyester-based pressure-sensitive adhesive composition can be used for electronic members, optical members, building members, and the like. It can be suitably used for bonding applications.

Claims (12)

It contains a polyester resin (A) having a structural unit derived from a polyvalent carboxylic acid (a1) and a structural unit derived from a polyol (a2), and a petroleum resin-based tackifier (B) having a number average molecular weight of 400 to 8000. The content of the petroleum resin-based pressure-sensitive adhesive (B) having a number average molecular weight of 400 to 8000 is 0.01 to 50 parts by weight with respect to 100 parts by weight of the polyester-based resin (A). Adhesive composition. The polyester-based pressure-sensitive adhesive composition according to claim 1, wherein the petroleum resin-based pressure-sensitive adhesive (B) has an aromatic ring structure. The polyester-based pressure-sensitive adhesive composition according to claim 1 or 2, wherein the softening point of the petroleum resin-based pressure-sensitive adhesive (B) is 30 to 200 ° C. The pressure-sensitive adhesive composition according to any one of claims 1 to 3, wherein the acid value of the petroleum resin-based pressure-sensitive adhesive (B) is 5 mgKOH / g or less. The polyester-based pressure-sensitive adhesive composition according to any one of claims 1 to 4, wherein the polyester-based resin (A) has a glass transition temperature of −80 to 20 ° C. The polyester-based pressure-sensitive adhesive composition according to any one of claims 1 to 5, wherein the polyester-based resin (A) has an ester bond concentration of 3 to 9 mmol / g. The polyester-based pressure-sensitive adhesive composition according to any one of claims 1 to 6, further comprising a hydrolysis inhibitor (C). The polyester-based pressure-sensitive adhesive composition according to any one of claims 1 to 7, further comprising a cross-linking agent (D). A polyester-based pressure-sensitive adhesive according to any one of claims 1 to 8, wherein the polyester-based pressure-sensitive adhesive composition is crosslinked. A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing the polyester-based pressure-sensitive adhesive according to claim 9. A pressure-sensitive adhesive sheet having a base material and a pressure-sensitive adhesive layer containing the polyester-based pressure-sensitive adhesive according to claim 9, wherein the pressure-sensitive adhesive layer is provided on at least one surface of the base material. .. A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing the polyester-based pressure-sensitive adhesive according to claim 9, wherein the pressure-sensitive adhesive sheet is a base material-less type having no base material.