JP2019023277A - Polyester-based adhesive and adhesive sheet thereof - Google Patents

Abstract

To provide a polyester-based adhesive which is excellent in characteristics of adhesive force, heat resistance, holding power, and transparency and is used for labels, adhesive tapes or sheets, and the like.SOLUTION: The adhesive contains a polyester resin (A) satisfying the following (1)-(3) and a curing agent (B): (1) the polyester resin (A) is a block polyester resin containing a copolyester segment (a) and an aliphatic segment (b); (2) a polycarboxylic acid component and a polyhydric alcohol component are contained as copolymerization components of the copolyester segment (a); and (3) the glass transition temperature of the copolyester segment (a) is 15°C or higher.SELECTED DRAWING: None

Description

  The present invention relates to a polyester pressure-sensitive adhesive having excellent heat resistance. More specifically, the pressure-sensitive adhesive sheet is excellent in properties such as adhesive strength and heat resistance, holding power and transparency, and is provided with a polyester-based pressure-sensitive adhesive used for labels, pressure-sensitive adhesive tapes or sheets, and a layer made of the pressure-sensitive adhesive. It is about.

  Adhesives are used in various forms of adhesive tapes in various fields such as electronics industry, sealing, painting, printing, and medical. The pressure-sensitive adhesive tape is easy to handle and exhibits practical performance as a pressure-sensitive adhesive immediately after use, making it an indispensable product in the industry.

  Resin materials used for adhesives can be broadly classified into rubbers, mainly natural rubber, acrylics made of acrylic acid ester copolymers, and silicones made of silicone rubber and silicone resin. Acrylic resins with properties, heat resistance, and weather resistance are most widely used. -

  As an adhesive using an acrylic resin, for example, as in Patent Document 1, an adhesive obtained by reacting with a small amount of a crosslinking agent using a carboxylic acid-containing monomer or a hydroxyl group-containing monomer mainly composed of n-butyl acrylate. Are known. Moreover, the adhesive which melt | dissolved the acrylate resin like the patent document 2 in the acryl monomer and hardened it by active energy ray is known. On the other hand, as a method for polymerizing acrylic resin, a polymerization method using a radical initiator such as azobisisobutyronitrile in a solution such as ethyl acetate is generally well known. Has a wide molecular weight distribution and contains a large amount of unreacted monomers and low molecular weight oligomers. For this reason, the acrylic pressure-sensitive adhesive cannot maintain sufficient adhesive force in a high temperature environment, and there is a problem that heat resistance at high temperature is insufficient. Also, in the method of reacting an acrylate resin and an acrylic monomer by active energy ray curing, a large amount of unreacted monomers and low molecular weight oligomers are likely to remain due to oxygen inhibition by a trace amount of oxygen in the air. There was a problem of insufficient heat resistance.

  In order to solve this problem, for example, in Patent Document 3 and Non-Patent Document 1, an acrylic resin polymerization method and a pressure-sensitive adhesive by living radical polymerization are studied. Adhesives using acrylic resins polymerized by living radical polymerization have a narrow molecular weight distribution and excellent heat resistance, but the polymerization time is longer than the conventional method, so there is a problem in terms of production . In addition, the molecular weight may be lower than that of a conventional acrylic resin obtained by random polymerization, and may not be suitable as a resin for an adhesive.

  Furthermore, in order to solve this problem, for example, in Patent Document 4, an adhesive using a copolyester resin is studied.

  However, if the copolymerization amount of aliphatic dicarboxylic acid or long-chain glycol is increased to lower the glass transition temperature of the polyester resin, it becomes a crystalline resin, resulting in poor solvent solubility, adhesion to the substrate, and transparency. There was a problem to do.

  Moreover, as a method for lowering the glass transition temperature of the polyester resin and maintaining the amorphous property of the resin, for example, in Patent Document 5, a polyester resin in which an aliphatic segment is further introduced into a polyester resin containing dimer acid or adipic acid as a main monomer A pressure sensitive adhesive is being investigated.

Japanese Patent No. 2672308 Japanese Patent No. 4868654 JP 2010-209283 A JP 2007-45914 A Japanese Patent No. 3090221

Journal of the Adhesion Society of Japan Vol. 52 no. 10 (2016)

  However, since the polyester resin of Patent Document 5 has a very low glass transition temperature of the copolyester segment, the total cohesive force after addition of caprolactone is a very low resin. It has become a resin from which strong adhesive force to the base material, which is a characteristic of the agent, cannot be obtained.

  The object of the present invention is to solve the above-mentioned problems that conventional acrylic pressure-sensitive adhesives and polyester pressure-sensitive adhesives have. In other words, an object of the present invention is to provide a polyester-based pressure-sensitive adhesive that is excellent in adhesive properties, heat resistance, holding power, and transparency properties, and that is used for labels, pressure-sensitive adhesive tapes or sheets.

  As a result of intensive studies to solve the above-mentioned problems, the present inventor has found that an adhesive having significantly improved adhesiveness, heat resistance and transparency can be obtained by the following method, and has completed the present invention. It was. That is, the present invention has the following configuration.

A pressure-sensitive adhesive containing a polyester resin (A) satisfying the following (1) to (3) and a curing agent (B).
(1) The polyester resin (A) is a block polyester resin containing a copolymerized polyester segment (a) and an aliphatic segment (b). (2) As a copolymerization component of the copolymerized polyester segment (a), a polyvalent carboxylic acid is used. The glass transition temperature of the (3) copolymer polyester segment (a) containing an acid component and a polyhydric alcohol component is 15 ° C. or higher.

  The copolymerized polyester segment (a) preferably contains a branched structure. The polyester resin (A) preferably contains 10 to 200 ppm of at least one compound selected from the group consisting of Al compounds, Ge compounds, Ti compounds, and Zn compounds.

  A pressure-sensitive adhesive sheet comprising a layer made of the pressure-sensitive adhesive on one side or both sides of a support.

  The polyester resin (A) used in the present invention has a specific structure and physical properties. Therefore, the pressure-sensitive adhesive containing the polyester resin (A) and the curing agent (B) exhibits a sufficient adhesive force at a pressure of about finger pressure and does not cause a decrease in initial adhesive force due to crystallization. Furthermore, it is possible to obtain a pressure-sensitive adhesive and its sheet that do not impair the heat resistance, durability, and mechanical strength that are the characteristics of the polyester resin. That is, the pressure-sensitive adhesive of the present invention has an excellent effect on adhesive properties, heat resistance, holding power and transparency.

  Hereinafter, the polyester-based pressure-sensitive adhesive which is an embodiment of the present invention will be described. The polyester-based pressure-sensitive adhesive in the present invention contains a polyester resin (A) and a curing agent (B) as essential components.

<Polyester resin (A)>
The polyester resin (A) used in the present invention is a block polyester resin comprising a combination of a copolymerized polyester segment (a) having a polyvalent carboxylic acid component and a polyhydric alcohol component as a copolymerization component and an aliphatic segment (b). is there.

  The copolymer polyester segment (a) contained in the polyester resin (A) used in the present invention comprises a polyvalent carboxylic acid component and a polyhydric alcohol component as a copolymer component. That is, the copolyester segment (a) is a polyester having a chemical structure obtained by condensation polymerization of a carboxylic acid component comprising a divalent or higher polyhydric carboxylic acid compound and an alcohol component comprising a divalent or higher polyhydric alcohol compound. It is preferably a resin, and at least one of a polycarboxylic acid compound and a polyhydric alcohol compound is a copolyester resin comprising two or more components. In the present invention, the condensation polymerization includes a dehydration condensation reaction between a polyvalent carboxylic acid and a polyhydric alcohol, and a transesterification reaction between the polyvalent carboxylic acid ester and the polyhydric alcohol. The polycarboxylic acid compound and the polyhydric alcohol compound are preferably copolyester resins mainly composed of a dicarboxylic acid component and a glycol component. Here, mainly means that the total of the dicarboxylic acid component and the glycol component occupies 50 mol% or more on a molar basis with respect to the total of all acid components and all alcohol components constituting the copolyester segment (a). It is preferable. The total of the dicarboxylic acid component and the glycol component is more preferably 70 mol% or more, further preferably 85 mol% or more, particularly preferably 95 mol% or more, and may be 100 mol%. Absent.

  The glass transition temperature of the copolymerized polyester segment (a) is 15 ° C. or higher, preferably 20 ° C. or higher, more preferably 25 ° C. or higher, and further preferably 30 ° C. or higher. When the glass transition temperature of the copolymerized polyester segment (a) is less than 15 ° C., the polyester resin (A) is inferior in cohesion and may be inferior in adhesion and holding power to the polar substrate. A minimum is not specifically limited, Preferably it is 90 degrees C or less, More preferably, it is 80 degrees C or less, More preferably, it is 70 degrees C or less. If the glass transition temperature is too high, the glass transition temperature of the polyester resin (A) may be high, resulting in a resin having poor adhesion.

  When the polyvalent carboxylic acid component of the copolymerized polyester segment (a) is 100 mol%, the content of the aromatic dicarboxylic acid component is preferably 40 mol% or more. Preferably it is 45 mol% or more, More preferably, it is 50 mol% or more. When it is less than 40 mol%, the mechanical strength of the resulting pressure-sensitive adhesive may be lowered, and sufficient adhesive strength may not be obtained. The upper limit is not particularly limited and may be 100 mol%, but is preferably 98 mol% or less, more preferably 95 mol% or less, and still more preferably 90 mol% or less.

  The aromatic dicarboxylic acid component is not particularly limited, and examples thereof include terephthalic acid, isophthalic acid, orthophthalic acid, and naphthalenedicarboxylic acid. These aromatic dicarboxylic acid components can be used alone or in combination of two or more. Preferred is terephthalic acid or isophthalic acid.

  Examples of dicarboxylic acid components other than aromatic dicarboxylic acids include aliphatic dicarboxylic acids. Specific examples include succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid and the like, but are not limited thereto. These aliphatic dicarboxylic acid components can be used alone or in combination of two or more. Other polyvalent carboxylic acid components include aromatic oxycarboxylic acids such as p-oxybenzoic acid and p- (hydroxyethoxy) benzoic acid, fumaric acid, maleic acid, itaconic acid, hexahydrophthalic acid and tetrahydrophthalic acid. It is also possible to use alicyclic dicarboxylic acids such as unsaturated alicyclic dicarboxylic acids such as 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid. Further, if necessary, trimellitic acid (hereinafter also referred to as TMA), trimesic acid, pyromellitic acid, and other tri- and tetracarboxylic acids and anhydrides thereof may be included. These carboxylic acids can be used alone or in combination of two or more. These polycarboxylic acid components are preferably 5 mol% or less, more preferably 4 mol% or less, and even more preferably 3 mol% or less when the total polycarboxylic acid component is 100 mol%. is there. If the amount is too large, gelation due to the formation of a three-dimensional structure may occur during the polymerization of the copolyester segment (a), resulting in a resin insoluble in the solvent (C).

  When the polyhydric alcohol component of the copolymerized polyester segment (a) is 100 mol%, the content of the glycol component having a hydrocarbon group in the side chain is preferably 10 mol% or more. Preferably it is 20 mol% or more, More preferably, it is 30 mol% or more. If it is less than 10 mol%, the crystallinity of the resulting pressure-sensitive adhesive may increase, and sufficient adhesive strength may not be obtained. Although an upper limit is not specifically limited, It is preferable that it is 90 mol% or less, More preferably, it is 80 mol% or less. If the amount is too large, the adhesion to the polar substrate may be reduced, or the polycondensation reaction time during synthesis of the polyester resin may be prolonged, which may adversely affect productivity.

  As the glycol component having a hydrocarbon group in the side chain, an aliphatic glycol having a hydrocarbon group in the side chain is preferably used. Here, the side chain means a hydrocarbon group (carbon chain) connecting two hydroxyl groups as a main chain and branched from the main chain. The number of side chains branched from the main chain is not particularly limited, preferably 1 to 3, and more preferably 1 to 2. Moreover, it is preferable that the total carbon number of a side chain is 1-4, More preferably, it is 2-3. By setting it within the above range, a decrease in initial adhesive force due to the crystallinity of the copolyester resin (A) does not occur, and further, an improvement in hydrolysis resistance of the copolyester resin (A) can be expected.

  Specific examples of the aliphatic glycol having a hydrocarbon group in the side chain include 1,2-propanediol, 2,2-dimethyl-1,3-propanediol (hereinafter also referred to as neopentyl glycol or NPG), 2- Methyl-1,3-propanediol (hereinafter also referred to as 2MG), 2-ethyl-1,3-propanediol, 2-methyl-1,4-butanediol, 2,2-dimethyl-1,4-butanediol 2,3-dimethyl-1,4-butanediol, 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 2,3-dimethyl-1,5-pentanediol, 3, , 3-dimethyl-1,5-pentanediol and the like, but not limited thereto. These aliphatic glycol components having a hydrocarbon group in the side chain can be used alone or in combination of two or more. NPG or 3-methyl-1,5-pentanediol is preferred.

  Other aliphatic glycols include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, dipropylene Examples include glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. These aliphatic glycol components can be used alone or in combination of two or more.

  Other glycols include 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, tricyclodecanediol, bisphenol A ethylene oxide adduct and propylene oxide adduct, hydrogenation An ethylene oxide adduct and a propylene oxide adduct of bisphenol A can also be used. In addition to these, triols such as trimethylolethane, trimethylolpropane, glycerin, pentaerythritol, and tetraol may be used in combination. These polyhydric alcohol components can be used alone or in combination of two or more. These polyhydric alcohol components are preferably 5 mol% or less, more preferably 4 mol% or less, still more preferably 3 mol% or less, when the total polyhydric alcohol component is 100 mol%. If the amount is too large, gelation due to formation of a three-dimensional structure may occur during polymerization of the polyester resin (A), resulting in a resin insoluble in the solvent (C).

  The copolymerized polyester segment (a) preferably contains a branched structure. Examples of the copolymer component containing a branched structure include tri- and tetracarboxylic acids such as trimellitic acid, trimesic acid and pyromellitic acid, and anhydrides thereof as polyvalent carboxylic acid components. Examples of the polyhydric alcohol component include triols such as trimethylolethane, trimethylolpropane, glycerin and pentaerythritol, and tetraols. These may be used alone or in combination. Since the polyester resin (A) having a copolymerized polyester segment (a) containing a branched structure has an increased reactivity with the curing agent (B), it becomes a preferable resin when used as an adhesive.

  The amount of the copolymer component containing a branched structure in the copolymer polyester segment (a) is preferably 5 mol% or less when the total amount of the total polyvalent carboxylic acid or total polyhydric alcohol component is 100 mol%. More preferably, it is 4 mol% or less, More preferably, it is 3 mol% or less. When the copolymerization amount exceeds 5 mol%, gelation due to the formation of a three-dimensional structure may occur during the polymerization of the copolymerized polyester segment (a), resulting in a resin insoluble in the solvent (C).

As a method for producing the copolyester segment (a), a known method can be employed. For example, the target copolymerized polyester segment (a) can be obtained by esterifying the polyhydric carboxylic acid and the polyhydric alcohol component at 150 to 250 ° C. and then polycondensing at 230 to 300 ° C. under reduced pressure. it can. In this case, a transesterification or esterification reaction catalyst or a polycondensation catalyst can be used as appropriate.
When a hydrophilic polar group is introduced, it is preferable to add a monovalent inorganic salt such as sodium acetate or potassium acetate as a polymerization stabilizer.

  The polyester resin (A) contains the aliphatic segment (b) as a block component. The aliphatic segment (b) is preferably composed of an aliphatic component (total aliphatic). The aliphatic segment (b) preferably contains an aliphatic polyester, more preferably an all aliphatic polyester. As a method for introducing the aliphatic polyester, for example, after the copolymerized polyester segment (a) is polymerized, a cyclic ester monomer which is a ring-opening polymerizable monomer under normal pressure and nitrogen atmosphere is added. The ring-opening polymerization of the cyclic ester monomer enables block polymerization with the copolymerized polyester segment (a).

  Cyclic ester monomers include lactide, β-propiolactone, β-butyrolactone, γ-butyrolactone, γ-hexanolactone, γ-octanolactone, δ-valerolactone, δ-hexalanolactone, δ-octanolactone , Ε-caprolactone, δ-dodecanolactone, α-methyl-γ-butyrolactone, β-methyl-δ-valerolactone, glycolide, lactide, and other aliphatic lactones. These cyclic ester monomers can be used alone or in combination of two or more. In particular, lactide and ε-caprolactone are preferable from the viewpoint of reactivity and availability.

  The aliphatic segment (b) may contain an aliphatic polyamide in addition to the aliphatic polyester. The aliphatic polyamide is preferably a total aliphatic polyamide. As a method for introducing the aliphatic polyamide, for example, after the copolymerized polyester segment (a) is polymerized, a cyclic amide monomer is added together with the cyclic ester monomer under normal pressure and nitrogen atmosphere. The cyclic amide monomer and the cyclic ester monomer undergo ring-opening polymerization, whereby the copolymerized polyester segment (a) can be block-polymerized.

  Examples of the cyclic amide monomer include ε-caprolactam, δ-valerolactam, γ-butyrolactam, β-propyllactam, and the like. These cyclic amide monomers can be used alone or in combination of two or more. In particular, ε-caprolactam is preferable from the viewpoint of reactivity and availability.

  The aliphatic segment (b) is preferably 100 mol% or more, more preferably 110 mol%, when the total of the polyvalent carboxylic acid component and the polyhydric alcohol component of the copolymerized polyester segment (a) is 200 mol%. It is at least mol%, more preferably at least 120 mol%. If the amount is too small, the holding power and transparency may be lowered. Moreover, it is preferable that it is 300 mol% or less, More preferably, it is 250 mol% or less, More preferably, it is 220 mol% or less. If the amount is too large, the polyester resin (A) may crystallize, resulting in a resin having poor solubility in a solvent or a resin having poor adhesion to a substrate.

  In the aliphatic segment (b), the content of the aliphatic polyester is preferably 80 mol% or more, more preferably 90 mol% or more, still more preferably 95 mol% or more, and even 100 mol% is a problem. Absent. If the amount is too small, the glass transition temperature of the polyester resin (A) may be high, and the resin may have inferior adhesion to the substrate.

  The number average molecular weight of the polyester resin (A) is desirably 10,000 or more. Preferably it is 12,000 or more, More preferably, it is 15,000 or more. If the number average molecular weight is too small, the molecular weight between crosslinks is small, so that the pressure-sensitive adhesive becomes too hard and the adhesive strength may decrease. Moreover, it is preferable that it is 100,000 or less, More preferably, it is 70,000 or less, More preferably, it is 50,000 or less. If the number average molecular weight is too large, the resin cannot sufficiently react with the curing agent (B), so that heat resistance and heat-and-moisture resistance may be reduced.

  The weight average molecular weight of the polyester resin (A) is preferably 40,000 or more. Preferably it is 50,000 or more, More preferably, it is 60,000 or more. If the weight average molecular weight is too small, the molecular weight between crosslinks is small, so that the pressure-sensitive adhesive becomes too hard and the adhesive strength may decrease. Moreover, it is preferable that it is 300,000 or less, More preferably, it is 280,000 or less, More preferably, it is 250,000 or less. If the weight average molecular weight is too large, the resin cannot sufficiently react with the curing agent (B), so that the heat resistance and heat-and-moisture resistance may be reduced.

  The number average molecular weight (Mn) and the weight average molecular weight (Mw) of the present invention are measured as follows. A sample (polyester resin (A)) was dissolved in tetrahydrofuran so that the sample concentration was 0.5% by mass and filtered through a polytetrafluoroethylene membrane filter having a pore diameter of 0.5 μm as a measurement sample. . Using a gel permeation chromatograph (GPC) 150c manufactured by Waters with tetrahydrofuran as the mobile phase and a differential refractometer as the detector, gel the average molecular weight of the polyester resin (A) at a column temperature of 35 ° C. and a flow rate of 1 ml / min. Analyze by permeation chromatography. As the column, Showa Denko Co., Ltd. shodex KF-802, KF-804, KF-806 connected in series is used. A calibration curve of monodisperse standard polystyrene is used as the molecular weight standard. However, when the sample does not dissolve in tetrahydrofuran, N, N-dimethylformamide is used instead of tetrahydrofuran. Low molecular compounds (oligomers and the like) having a number average molecular weight of less than 1000 are omitted without counting.

The acid value of the polyester resin (A) is preferably 50 equivalents / 10 ⁶ g or less, more preferably 30 equivalents / 10 ⁶ g or less. When the acid value is too high, the heat-and-moisture resistance of the obtained pressure-sensitive adhesive tends to decrease. The lower limit is not particularly limited, and may be 0 equivalent / 10 ⁶ g.

  The glass transition temperature of the polyester resin (A) is preferably −15 ° C. or lower. More preferably, it is -25 degreeC, More preferably, it is -30 degrees C or less, Most preferably, it is -35 degrees C or less. When the glass transition temperature exceeds −15 ° C., the tackiness of the pressure-sensitive adhesive is weak, and the substrate adhesion at normal temperature may be deteriorated. A minimum is not specifically limited, It is preferable that it is -100 degreeC or more, More preferably, it is -80 degreeC or more, More preferably, it is -60 degreeC or more.

  The polyester resin (A) is preferably an amorphous resin. By being an amorphous resin, excellent adhesiveness can be expressed. Here, the term “amorphous” refers to a clear melting peak in the process of using a differential scanning calorimeter (DSC) once cooled to −100 ° C. and then heated to 150 ° C. at a rate of 20 ° C./min. Points not shown.

  The polyester resin (A) may be able to improve the adhesiveness to the base material by introducing a polar group as a substituent for the resin side chain or the resin main chain. Examples of the polar group having such an action include a sulfonic acid group, a carboxyl group, a phosphoric acid group, and metal salts thereof, but a sulfonic acid metal base and a carboxyl group are more preferable, and the heat and heat resistance of the resin is taken into consideration. In this case, a carboxyl group is most preferable. Moreover, these polar groups may be used alone or in combination as required.

  The method for introducing a carboxyl group into the polyester resin (A) is not particularly limited. For example, after the copolymerized polyester segment (a) is polymerized and the aliphatic segment (b) is added, an acid anhydride is added under normal pressure and a nitrogen atmosphere to carry out an addition reaction, or an acid anhydride is added to the polyester oligomer. There is a method of introducing a carboxyl group into the copolymerized polyester segment (a) by charging and then increasing the molecular weight by a polycondensation reaction under reduced pressure. The former method is preferable because the target acid value is easily obtained. Suitable acid anhydrides for these reactions include trimellitic anhydride, phthalic anhydride, pyromellitic anhydride, succinic anhydride, maleic anhydride, 1,8-naphthalic anhydride, -1,2-cyclohexane anhydride. Dicarboxylic acid, cyclohexane-1,2,3,4-tetracarboxylic acid-3,4-anhydride, ethylene glycol bisanhydro trimellitate, 5- (2,5-dioxotetrahydro-3-furanyl) -3 -Methyl-3-cyclohexene-1,2-dicarboxylic anhydride, naphthalene-1,8: 4,5-tetracarboxylic dianhydride, and the like, and one or more of these can be selected Can be used.

  The method for introducing the sulfonic acid metal base into the polyester resin (A) is not particularly limited. For example, metal salts such as 5-sulfoisophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, 5 [4-sulfophenoxy] isophthalic acid, 2-sulfo-1,4-butanediol, 2,5-dimethyl -3-Sulfonate metal base is easily introduced by using dicarboxylic acid or glycol containing sulfonic acid metal base such as metal salt such as -3-sulfo-2,5-hexanediol as a monomer of copolymerized polyester segment (a). can do.

  The polyester resin (A) used in the present invention may be subjected to molecular chain extension by diisocyanate after polymerization within a range not impairing the effects of the present invention.

  Furthermore, depending on the purpose of use of the polyester resin (A), additives such as inorganic particles, fluorescent brighteners, UV inhibitors, infrared absorbers, heat stabilizers such as hindered phenols or hindered amines, and antioxidants are added. It may be included.

  Examples of the transesterification reaction catalyst include fatty acid salts such as Zn, Cd, Mg, Mn, Co, Ca, and Ba, carbonates, Pb, Zn, Sb, and Ge oxides.

  Copolymerization of polyester resin (A) Any polycondensation catalyst commonly used for polymerizing polyester segment (a) may be used. For example, Al compound, Sb compound, Ge compound, Ti compound, Zn Compounds. Among these, the use of an Al compound, a Ge compound, a Ti compound, or a Zn compound is particularly preferable from the viewpoint of the reaction rate during polymerization and the transparency of the obtained polyester resin (A). Moreover, you may use these compounds together.

  The Al compound has low activity by itself, and preferably has increased catalytic activity in combination with other metals. Al / Co, Al / Li, Al / Na, Al / Mg, etc. are preferably used. Further, it is preferable to further improve catalytic activity by combining a phosphorus compound with Al or a combination of Al and another metal, and a particularly preferable phosphorus compound is Ar—CH 2 —P (═O) (OH) 2. (Ar represents an aryl group, and a hindered phenol structure is particularly preferred). The phosphonic acids have an aromatic group in the molecule, and also include these alkyl esters and salt compounds.

  Examples of the Ge compound include germanium dioxide and germanium tetrachloride, and among these, germanium dioxide is preferable.

  Examples of Ti compounds include tetra-n-propyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, tetraisobutyl titanate, tetra-tert-butyl titanate, tetracyclohexyl titanate, tetraphenyl titanate, titanium oxalate, titanate phthalate, tri Mellitic acid titanate, pyromellitic acid titanate and the like can be mentioned, and among these, tetra-n-butoxy titanate and trimellitic acid titanate are preferable. In particular, trimellitic titanate is preferable in terms of yellowing resistance and heat stability.

  Examples of the Sb compound include antimony trioxide, antimony pentoxide, antimony acetate, and antimony glycoloxide. Of these, antimony trioxide is preferable.

  Examples of the Zn compound include organic acid salts such as zinc acetate and zinc benzoate, chlorides such as zinc chloride, alkoxides such as zinc methoxide, and zinc acetylacetonate. Among these, zinc acetate is preferable.

  The polyester resin (A) preferably contains 10 to 200 ppm of at least one compound selected from the group consisting of Al compounds, Ge compounds, Ti compounds and Zn compounds. More preferably, it is 10-100 ppm.

Composition and the composition ratio of the polyester resin (A) and copolymerization polyester segment (a) is a ^{1 H-NMR} to measure dissolved polyester resin (A) and copolymerization polyester segment (a) in a solvent such as deuterochloroform It can be calculated from the integration ratio.

  The polymerization catalyst species and polymerization catalyst amount of the polyester resin (A) can be determined by ICP emission spectroscopic analysis.

<Curing agent (B)>
The curing agent (B) used in the present invention is not particularly limited as long as it is a compound that reacts with the polyester resin (A) and cures. Preferred is an isocyanate curing agent (B1) or an epoxy curing agent (B2).

  The isocyanate curing agent (B1) is preferably a polyfunctional isocyanate compound, and examples thereof include aromatic or aliphatic diisocyanate compounds, trivalent or higher polyisocyanate compounds, and the like. These isocyanate curing agents (B1) may be either low molecular compounds or high molecular compounds. For example, aliphatic diisocyanates such as tetramethylene diisocyanate and hexamethylene diisocyanate, aromatic diisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate, fats such as hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, dimer acid diisocyanate, and isophorone diisocyanate. Examples thereof include cyclic diisocyanates or trimers of these isocyanate compounds. In addition, a terminal isocyanate group obtained by reacting an excess amount of the isocyanate compound with a low molecular active hydrogen compound such as ethylene glycol, propylene glycol, trimethylolpropane, glycerin, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, or triethanolamine. Containing compounds. Furthermore, the terminal isocyanate group containing compound obtained by making it react with the excess amount of the said isocyanate compound, the polymer active hydrogen compound of various polyester polyols, polyether polyols, polyamides etc. is mentioned. These isocyanate compounds can be used alone or in combination of two or more. Especially, the trimer of a hexamethylene diisocyanate compound is especially preferable.

  The epoxy curing agent (B2) is preferably a polyfunctional epoxy compound, and examples thereof include aromatic or aliphatic diglycidyl ethers and trivalent or higher polyglycidyl ethers. These epoxy compounds may be either low molecular compounds or high molecular compounds. For example, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol Diglycidyl ether, hydrogenated bisphenol-type diglycidyl ether, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, tetraglycidyl diaminodiphenylmethane, triglycidyl paraaminophenol, tetraglycidyl bisaminomethyl Siku Hexanone, N, N, N ', N'- tetraglycidyl -m- xylene diamine and the like. These epoxy compounds can be used alone or in combination of two or more. Of these, N, N, N ′, N′-tetraglycidyl-m-xylenediamine and a glycerol type epoxy resin which is an aliphatic epoxy compound are particularly preferable in terms of reactivity and adhesiveness.

  As a compounding quantity of a hardening | curing agent (B), it is preferable that it is 0.1 mass part or more with respect to 100 mass parts of polyester resins (A), More preferably, it is 0.3 mass part or more, More preferably 0.5 parts by mass or more. If the amount is too small, the curability may be insufficient and the heat resistance may decrease. Moreover, it is preferable that it is 5 mass parts or less, More preferably, it is 4 mass parts or less, More preferably, it is 3 mass parts or less. If the amount is too large, the pressure-sensitive adhesive becomes hard, and the tackiness to the substrate may be reduced due to insufficient tack.

  In order to express a good function as a pressure-sensitive adhesive by crosslinking of the polyester resin (A) and the curing agent (B), the solvent-insoluble component (gel fraction) after the crosslinking treatment of the polyester resin (A) is 40 masses. % Or more is preferable. More preferably, it is 50 mass% or more. When the solvent-insoluble component (gel fraction) after the crosslinking treatment of the polyester resin (A) is less than 40% by mass, the adhesive strength tends to increase, but the cohesive strength of the adhesive is insufficient and the mechanical strength is increased. In some cases, the peeled state is not interfacial peeling but cohesive peeling, and adhesive residue is generated on the substrate, or sufficient heat resistance may not be obtained. Moreover, it is preferable that the upper limit of a solvent insoluble component is 85 mass%, More preferably, it is 75 mass% or less. When the solvent-insoluble content after the crosslinking treatment of the polyester resin (A) exceeds 85% by mass, the heat resistance becomes high, but the tackiness of the pressure-sensitive adhesive becomes insufficient, making it difficult to bond, and sufficient adhesive strength cannot be obtained. There is a case.

  When the pressure-sensitive adhesive is formed by crosslinking between the polyester resin (A) and the curing agent (B), the solvent-insoluble component after the crosslinking treatment of the polyester resin (A) is adjusted by increasing or decreasing the amount of the curing agent (B). Thus, it is possible to adjust the physical properties as an adhesive. Generally, when the amount of the curing agent (B) added is small and the amount of solvent insoluble after the crosslinking treatment of the polyester resin (A) is small, the tack and adhesive strength tend to increase, but the holding power and heat resistance Tend to go down. On the other hand, when the addition amount of the curing agent (B) is increased and the solvent insoluble content after the crosslinking treatment of the polyester resin (A) is large, the holding power and heat resistance increase, but the tack and adhesive strength tend to decrease. It is in.

Further, the storage elastic modulus (23 ° C.) after the crosslinking treatment of the polyester resin (A) is not particularly limited, but is preferably 1 × 10 ⁶ Pa or less, more preferably 6 × 10 ⁵ Pa or less, for example. is there. When the storage elastic modulus (23 ° C.) after the crosslinking treatment of the polyester resin (A) exceeds 1 × 10 ⁶ Pa, the pressure-sensitive adhesive becomes hard and the pressure-sensitive adhesiveness may be lowered. Further, when the storage elastic modulus (23 ° C.) after the crosslinking treatment of the polyester resin (A) is lower than 1 × 10 ⁴ Pa, the cohesive force of the pressure-sensitive adhesive is insufficient, and it becomes difficult to obtain sufficient heat resistance. The lower limit of the storage modulus (23 ° C.) after the crosslinking treatment of the resin (A) is preferably 1 × 10 ⁴ Pa, more preferably 5 × 10 ⁴ Pa.

  As curing agents other than the isocyanate curing agent (B1) and the epoxy curing agent (B2), amino resins such as methylated melamine, butylated melamine, benzoguanamine, urea resin, acid anhydrides, imidazoles, phenol resins, and the like are known. Compounds. These curing agents can be used in combination with a known catalyst or accelerator selected according to the type. Moreover, you may use these compounds together.

<Adhesive>
The pressure-sensitive adhesive of the present invention is a composition containing a polyester resin (A) and a curing agent (B). The pressure-sensitive adhesive preferably further contains a solvent (C) to form a varnish. It is preferable to mix the curing agent (B) after dissolving the polyester resin (A) in the solvent (C) to obtain a polyester resin varnish. 70-100 degreeC is preferable and, as for the temperature at the time of melt | dissolving a polyester resin (A) and obtaining a polyester resin varnish, 80-90 degreeC is more preferable. If the dissolution temperature is too low, the entanglement between the molecular chains of the polyester resin (A) cannot be sufficiently solved, and dissolution may be insufficient. Moreover, when melt | dissolution temperature is too high, there exists a possibility that the deterioration of a polyester resin (A) may be caused.

<Solvent (C)>
The solvent (C) used in the present invention is not particularly limited as long as it dissolves the polyester resin (A) and the curing agent (B), but is an organic solvent that dissolves the polyester resin (A) and the curing agent (B). It is preferable that Specifically, methyl ethyl ketone, toluene, cyclohexanone, dimethylacetamide, dimethylformamide, N-methylpyrrolidone, tetrahydrofuran, 1,4-dioxane, 1,3-dioxane, 1,3-dioxolane, 1,2-hexanediol, ethyl Examples thereof include carbitol butyl carbitol, propylene glycol monopropyl ether, propylene glycol monobutyl ether, triethylene glycol monobutyl ether and the like. These solvents (C) can be used alone or in combination of two or more. Of these, methyl ethyl ketone, toluene, ethyl acetate, cyclohexanone, and the like are preferable in terms of resin solubility.

  As the solvent (C) used in the present invention, an organic solvent which is a poor solvent in which the polyester resin (A) does not dissolve or swell can be used as long as the performance of the present invention is not impaired. Here, it is preferable to use the organic solvent which becomes a poor solvent in the range of 0 to 70% by mass ratio with respect to the organic solvent in which the polyester resin (A) can be dissolved or swollen. More preferably, it is 5 to 50%. If a poor solvent exceeding 70% is used, the polyester resin (A) may be aggregated and settled.

  It is preferable that a solvent (C) is 50 mass parts or more with respect to 100 mass parts of polyester resins (A), More preferably, it is 100 mass parts or more, More preferably, it is 200 mass parts or more. If the amount is too small, the solution viscosity becomes high and workability may be lowered. Moreover, it is preferable that it is 2000 mass parts or less, More preferably, it is 1500 mass parts or less, More preferably, it is 1000 mass parts or less. If the amount is too large, the solution viscosity becomes low, and it may be difficult to control the thickness of the pressure-sensitive adhesive layer laminated on the support.

  The polyester resin varnish of the present invention is preferably produced at a resin solid content concentration of 5 to 75% by mass. More preferably, it is 10-60 mass%, More preferably, it is 15-55 mass%, Most preferably, it is the range of 20-50 mass%. When the resin solid content concentration is too high, the solution viscosity becomes high and workability is greatly reduced. Moreover, when too low, solution viscosity will become low and it may become difficult to control the thickness of the apply | coated adhesive layer.

  The pressure-sensitive adhesive of the present invention may contain a plurality of polyester-based resins and other resins as necessary, as long as the curing of the present invention is not impaired. Other resins are not particularly limited, and for example, acrylic resins, polyester resins, alkyd resins, epoxy resins, urethane resins and the like can be used.

  The pressure-sensitive adhesive of the present invention includes conventionally known various tackifiers, powders such as inorganic or organic fillers, metal powders, pigments, particulates, foils, softeners, plasticizers, anti-aging agents, Various conventionally known additives such as a conductive agent can be arbitrarily blended. In some cases, the combined use of the tackifier may improve the balance between tackiness and heat resistance (or balance between mechanical strength and flexibility).

<The manufacturing method of the adhesive sheet of this invention>
The pressure-sensitive adhesive sheet in the present invention has a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive. The pressure-sensitive adhesive layer may be formed on the support or may not be formed on the support. When the pressure-sensitive adhesive layer is formed on the support, it can be formed on one side (pressure-sensitive adhesive layer / support) or both sides (pressure-sensitive adhesive layer / support / pressure-sensitive adhesive layer) of the support. As an adhesive sheet, what has a support body and the adhesive layer which consists of the said adhesive agent formed in the single side | surface or both surfaces of a support body is preferable. When the pressure-sensitive adhesive layer is formed on the support, the pressure-sensitive adhesive layer can be formed by applying and drying the pressure-sensitive adhesive so that the thickness after drying is usually about 1 to 500 μm. . In addition, the crosslinking process with a polyester resin (A) and a hardening | curing agent (B) can be suitably performed during the manufacturing process of an adhesive sheet or after the process. For the application of the pressure-sensitive adhesive, a conventional method can be employed.

  Although the conditions at the time of apply | coating an adhesive on a support body and drying are not specifically limited, It is preferable that it is 40-250 degreeC. If it is less than 40 degreeC, drying time will take time and it is not rational as industrial production. Moreover, there is a possibility that the coating film is not completely dried. On the other hand, if it exceeds 250 ° C., a high-performance drying furnace is required, which is not desirable. The drying method is not limited, but known methods such as a hot air drier, induction heating, near infrared heating, far infrared heating, indirect heating can be applied. If it is applied to a steel plate, a method may be used in which the steel plate is preheated, applied when heated, and dried with residual heat.

  The pressure-sensitive adhesive layer may be protected by a release liner. In the pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive layer is formed on one side of the support, the surface of the support opposite to the pressure-sensitive adhesive layer is subjected to a release treatment, whereby the pressure-sensitive adhesive layer is utilized using the release-treated surface. It is also possible to protect. By using such a release liner or the release treatment surface of the support, it is possible to produce pressure-sensitive adhesive sheets in the form of sheets or tapes by stacking them in a sheet form or winding them in a roll form. .

  As described above, the thickness of the pressure-sensitive adhesive layer (thickness after drying) is usually selected from the range of 1 to 500 μm, preferably 5 to 300 μm, more preferably about 10 to 200 μm.

  In the pressure-sensitive adhesive sheet, the material for the support (base material) is not particularly limited, and the material for the support used in known pressure-sensitive adhesive sheets (such as pressure-sensitive adhesive tapes) can be used. Examples of the material of the support include, for example, high-quality paper, glassine paper, kraft paper, Japanese paper, etc .; porous materials such as single or mixed woven or non-woven fabrics made of rayon, glass, polyester, etc .; cellophane, polyethylene, polypropylene Plastic film made of plastic such as polyester such as polyethylene terephthalate; Rubber sheet made of natural rubber, butyl rubber, etc .; Foam sheet made of polyurethane, polychloropropylene, etc .; Metal foil such as aluminum foil, copper foil; Etc. As the support, a plastic film such as a polyester film, or a porous material such as paper or nonwoven fabric can be suitably used. A support body can be used individually or in combination of 2 or more types. The support may be a single layer or a multilayer.

  The thickness in particular of a support body is not restrict | limited, For example, it can select from the range of about 1-100 micrometers, Preferably about 10-50 micrometers.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the examples. In the examples, the term “parts” means parts by mass. Each measurement item followed the following method.

(1) Composition of polyester resin (A), copolymerized polyester segment (a) Composition and composition ratio of polyester resin (A) and copolymerized polyester segment (a) are determined by ¹ H-NMR measurement (proton type) at a resonance frequency of 400 MHz. Nuclear magnetic resonance spectroscopy). The measuring apparatus used was an NMR apparatus 400-MR manufactured by VARIAN, and deuterated chloroform (with trifluoroacetic acid added) was used as the solvent.

(2) Polymerization Catalyst Type and Polymerization Catalyst Amount of Polyester Resin (A) Sb Compound / Ge Compound Analysis Method After weighing 0.5 g of a sample into a platinum crucible, 5 ml of 5% yttrium nitrate ethanol solution is added and 350 on a hot plate. The temperature was raised to ° C. After sufficiently reacting with the reagent, it was incinerated at 550 ° C. using an electric furnace, and the obtained incinerated product was dissolved in 1.2N hydrochloric acid. The solution in a constant volume of 20 ml was measured with an ICP emission spectrometer (SPECTRO BLUE manufactured by Hitachi High-Tech Science Co., Ltd.).

Analytical method of Al compound / Ti compound / Zn compound A sample of 0.5 g was weighed in a platinum crucible and then heated to 350 ° C. on a hot plate. Ashing was performed at 550 ° C. using an electric furnace, and the resulting ashed product was dissolved in 1.2N hydrochloric acid. The solution in a constant volume of 20 ml was measured with an ICP emission spectrometer (SPECTRO BLUE manufactured by Hitachi High-Tech Science Co., Ltd.).

(3) Number average molecular weight (Mn) / weight average molecular weight (Mw)
A sample (polyester resin (A)) was dissolved in tetrahydrofuran so that the sample concentration was 0.5% by mass and filtered through a polytetrafluoroethylene membrane filter having a pore size of 0.5 μm as a measurement sample. . Using a gel permeation chromatograph (GPC) 150c manufactured by Waters with tetrahydrofuran as the mobile phase and a differential refractometer as the detector, gel the average molecular weight of the polyester resin (A) at a column temperature of 35 ° C. and a flow rate of 1 ml / min. Analysis was by permeation chromatography. As the column, Showa Denko Co., Ltd. shodex KF-802, KF-804, KF-806 connected in series was used. The molecular weight standard was measured using a calibration curve of monodisperse standard polystyrene. However, when the sample did not dissolve in tetrahydrofuran, N, N-dimethylformamide was used instead of tetrahydrofuran. Low molecular compounds (oligomers and the like) having a number average molecular weight of less than 1000 were omitted without counting.

(4) Glass transition temperature (Tg)
It measured with the differential scanning calorimeter (SII company, DSC-200). 5 mg of a sample (polyester resin (A) or copolymer polyester segment (a) of polyester resin (A)) was placed in an aluminum press-lid container, and crimped and sealed. First, it was cooled to −100 ° C. using liquid nitrogen, and then heated to 150 ° C. at 20 ° C./min. In the endothermic curve obtained in the process, the base line extension before the endothermic peak (below the glass transition temperature) and the tangent to the endothermic peak (maximum slope between the peak rising part and peak apex) The temperature at the intersection with the tangent line indicating the glass transition temperature was defined as the glass transition temperature.

(5) Acid value 0.2 g of a sample (polyester resin (A)) was precisely weighed and dissolved in 40 ml of chloroform. Next, titration was performed with an ethanol solution of 0.01 N potassium hydroxide. Phenolphthalein was used as an indicator. Potassium hydroxide equivalent was calculated | required with respect to the polyester resin (A), and it converted and calculated | required in the unit of equivalent / 10 < ⁶ > g.

(6) Preparation method of adhesive tape Adhesive is applied to a polyester film (Toyobo E5101, thickness 50 μm, corona-treated surface) with an applicator so that the dry film thickness (film thickness after drying) is 50 μm, and the solvent is volatilized. Then, a polypropylene film (Toyobo P2161, thickness 50 μm, non-corona-treated surface) was pressure-bonded using a dry laminator. The dry lamination was performed at a roll temperature of 25 ° C., a roll load of 3 kg / cm, and a speed of an object to be bonded of 1 m / min. Next, aging was performed at 40 ° C. for 72 hours to cure the pressure-sensitive adhesive, and the polypropylene film was peeled off to obtain a polyester film / pressure-sensitive adhesive laminate. Hereinafter, this laminate is referred to as an adhesive sheet A.

(7) Measuring method of storage elastic modulus An adhesive was applied to a polypropylene film (Toyobo P2161, thickness 50 μm, non-corona-treated surface) with an applicator so that the dry film thickness was 50 μm, and the solvent was volatilized. The film (Toyobo P2161, thickness 50 μm, non-corona-treated surface) was pressure-bonded using a dry laminator. The dry lamination was performed at a roll temperature of 25 ° C., a roll load of 3 kg / cm, and a speed of an object to be bonded of 1 m / min. Next, the adhesive was cured by aging at 40 ° C. for 72 hours, and the polypropylene film was further peeled off to obtain a polypropylene film / adhesive laminate. Hereinafter, this laminate is referred to as an adhesive sheet B.
Using the dynamic viscoelasticity measuring device DVA-200 manufactured by IT Measurement Control Co., Ltd., this adhesive sheet B is measured in a shear mode with a thickness of about 1.0 mm (produced by laminating a 50 μm adhesive layer). Carried out. Measurements were carried out at a frequency of 10 Hz and a temperature increase rate of 4 ° C. per minute in a temperature range from −70 ° C. to 200 ° C., and the storage elastic modulus values at 23 ° C. are shown in Table 3.

(8) Gel fraction The pressure sensitive adhesive sheet A is cut into strips of 2.5 cm in length and 10 cm in width and the weight is measured (this weight is designated as A), and the mixture solution is toluene / methyl ethyl ketone = 1/1 (weight ratio). It was immersed for 1 hour. The strip-shaped adhesive sheet A was taken out and dried with a hot air dryer for 1 hour, and the weight was measured (this weight is designated as B). Thereafter, the pressure-sensitive adhesive layer remaining on the strip-shaped pressure-sensitive adhesive sheet A was scraped off, and the weight of only the polyester film was measured (this weight is defined as C). The numerical value calculated by the following formula was defined as the degree of cure (%). The evaluation results are shown in Table 3.
Gel fraction (%) = {(BC) / (AC)} × 100

(9) Adhesive strength At room temperature (23 ° C.), the adhesive sheet is cut into a width of 25 mm and a length of 200 mm, the adhesive layer surface is attached to the following substrate, and a 2 kg rubber roller from the top at a speed of 20 mm / sec. The pressure-sensitive adhesive sheet was pressure-bonded to the substrate by reciprocating twice. After 24 hours, the 180 ° peel adhesive strength was measured under the peel speed of 300 mm / min to obtain the adhesive strength. Moreover, the state of the peeled base material was confirmed, and the state of no interfacial peeling on the base material was judged as ◯, and the state where the cohesive peeling or the pressure-sensitive adhesive layer was transferred to the base material side was judged as x. The following materials were used.
Base material A: Polycarbonate base material (Mitsubishi Gas Chemical Co., Ltd. polycarbonate film IMR05 thickness 1.5 mm)
Base material B: Glass base material (Eagle XG glass thickness 1.1 mm)
Base material C: Stainless steel base material (SUS304 steel plate thickness 1.5 mm)

(10) Heat resistance A sample in which a pressure-sensitive adhesive sheet was bonded to a stainless steel substrate was prepared in the same manner as in the measurement of adhesive strength, and was left for 1 hour in a 150 ° C environment. Thereafter, the adhesive strength was measured and the peeled state was confirmed at room temperature (23 ° C.). Evaluation is the same as the measurement of adhesive strength.

(11) Holding force At room temperature (23 ° C.), the adhesive sheet is cut into a width of 25 mm and a length of 100 mm, and the 25 mm width and 25 mm length of the adhesive layer surface is attached to a stainless steel plate (SUS304). The rubber sheet was reciprocated twice at a speed of 20 mm / second, and the adhesive sheet and the stainless steel plate were pressure bonded. After standing at 23 ° C. for 30 minutes, a load of 1 kg was applied under conditions of room temperature (23 ° C.) 50 RH%, 80 ° C., 120 ° C., and 24 hours later, the distance (mm) by which the adhesive sheet was displaced from the stainless steel plate was measured. When the deviation is less than 0.1 mm, △, when the deviation is 0.1 mm or more and less than 0.5 mm, when the deviation is 0.5 mm or more and less than 25 mm, the deviation distance is described, and the adhesive sheet falls from the stainless steel plate Was marked with x.

(12) Transparency The pressure-sensitive adhesive sheet B is cut into a width of 25 mm and a length of 25 mm, the pressure-sensitive adhesive layer surface of the pressure-sensitive adhesive sheet B is attached to a glass plate having a thickness of 1.1 mm, and the polypropylene film is peeled off to form a glass plate / pressure-sensitive adhesive laminate. Obtained. This laminate was measured for total light transmittance and haze using NDH7000 manufactured by Nippon Denshoku Industries Co., Ltd.

Synthesis of polyester resin (A-1) In a reaction can equipped with a stirrer, a thermometer, a heater, a cooling device, and a condenser for distillation, 67 parts dimethylterephthalic acid, 67 parts dimethylisophthalic acid, trimellitic anhydride 3 parts, 54 parts of ethylene glycol, 55 parts of neopentyl glycol, 0.068 parts of tetrabutyl titanate were charged, and transesterification was performed at 180 ° C. for 3 hours. Next, the pressure was gradually reduced to 1 mmHg or less, and polymerization was carried out at 240 ° C. for 0.5 hour. Thereafter, 160 parts of ε-caprolactone was added under normal pressure and a nitrogen stream and reacted at 200 ° C. for 30 minutes for synthesis. The composition of the copolymer polyester obtained was terephthalic acid / isophthalic acid / trimellitic acid // ethylene glycol / neopentyl glycol // ε-caprolactone = 49/49/2 // 55/45 // 140 (molar ratio) Met. The results of the physical properties of this resin are shown in Table 1.

Synthesis of polyester resins (A-2) to (A-9) Polyester resins (A-2) to (A-2) to (A) which are polyester resins whose compositions are shown in Table 1 in the same manner as in the synthesis example of polyester resin (A-1). A-9) was synthesized. The measurement results of the resin physical properties are shown in Table 1. In the table, Ti, Ge, Sb and Zn represent tetrabutyl titanate, germanium dioxide, antimony trioxide and zinc acetate, respectively.

Synthesis of polyester resin (A-12) In a reaction vessel equipped with a stirrer, thermometer, heater, cooling device, and distillation cooler, 67 parts dimethylterephthalic acid, 67 parts dimethylisophthalic acid, trimellitic anhydride 3 parts, 54 parts of ethylene glycol, 56 parts of neopentyl glycol, 0.068 parts of tetrabutyl titanate were charged, and transesterification was carried out at 180 ° C. for 3 hours. Next, the pressure was gradually reduced to 1 mmHg or less, and polymerization was carried out at 240 ° C. for 0.5 hour. Thereafter, 160 parts of ε-caprolactone was added under normal pressure and a nitrogen stream and reacted at 200 ° C. for 30 minutes for synthesis. Thereafter, 0.7 part of succinic anhydride was further added and reacted at 200 ° C. for 30 minutes. The composition of the obtained copolyester was terephthalic acid / isophthalic acid / trimellitic acid // ethylene glycol / neopentyl glycol // ε-caprolactone /// succinic anhydride = 49/49/2 // 55/45 / / 140 /// 1 (molar ratio). The results of physical properties of this resin are shown in Table 2.

Synthesis of polyester resins (A-13) to (A-22) Polyester resins (A-13) to (A-13) which are polyester resins whose compositions are shown in Table 2 in the same manner as in the synthesis example of polyester resin (A-12) A-22) was synthesized. Table 2 shows the measurement results of the resin physical properties. In the table, Ti, Ge, Sb and Zn represent tetrabutyl titanate, germanium dioxide, antimony trioxide and zinc acetate, respectively.

Synthesis of acrylic resin (A-10) In a reaction can equipped with a stirrer, thermometer, heater, and cooling device, 69 parts by mass of butyl acrylate, 30 parts by mass of 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate 1 part by weight, 0.3 parts by weight of azobisisobutyronitrile, 0.3 parts by weight with respect to the total amount of acrylic monomers, and 137 parts by weight of ethyl acetate were charged. The radical polymerization reaction was carried out for 4 hours. The measurement results are shown in Table 3 together with the charged composition and the resin physical properties at the mass ratio of the obtained acrylic resin.

Synthesis of Acrylic Resin (A-11) An acrylic resin (A-11) which is an acrylic resin whose composition is shown in Table 3 was synthesized in the same manner as in the synthesis example of the acrylic resin (A-10). The measurement results of the resin physical properties are shown in Table 3.

Synthesis of acrylic resin (A-23) In a reaction can equipped with a stirrer, a thermometer, a heater, and a cooling device, 69 parts by mass of butyl acrylate, 30 parts by mass of 2-ethylhexyl acrylate, 1 part by mass of acrylic acid, Azobisisobutyronitrile was charged with 0.3 parts by weight of 0.3% by weight based on the total amount of acrylic monomers and 137 parts by weight of ethyl acetate. Nitrogen was introduced into the system, and the temperature was raised to 80 ° C. for 4 hours. To carry out radical polymerization reaction. The measurement results are shown in Table 4 together with the charged composition and the resin physical properties in the weight ratio of the obtained acrylic resin.

Synthesis of Acrylic Resin (A-24) An acrylic resin (A-24) which is an acrylic resin whose composition is shown in Table 4 was synthesized in the same manner as in the synthesis example of the acrylic resin (A-23). Table 4 shows the measurement results of the resin physical properties.

In Examples 1-16 and Comparative Examples 1-18, the obtained polyester resin and acrylic resin were dissolved in ethyl acetate so that the solid content concentration would be 30% by mass. An isocyanate curing agent or an epoxy curing agent was blended with this dissolved material in accordance with the amounts shown in Tables 5 and 6 to prepare an adhesive. The resin amounts in Tables 5 and 6 indicate values as resin solids. In Comparative Examples 5-6 and 15-16, ethyl acetate was added to the resin solution obtained at the time of synthesis so that the solid concentration was 30% by mass, and an isocyanate curing agent was blended according to the amounts in Tables 5 and 6 And used as an adhesive. The evaluation results of these pressure-sensitive adhesives are shown in Tables 5 and 6. The following isocyanate curing agents and epoxy curing agents were used.
Curing agent B1-1: Hexamethylene diisocyanate-modified polyfunctional isocyanate compound, Desmodur (registered trademark) N3200, manufactured by Bayer
Curing agent B1-2: Trimethylolpropane hexamethylene diisocyanate trimer addition isocyanate compound, Nippon Polyurethane Co., Ltd. Coronate (registered trademark) L
Curing agent B2-1: N, N, N ′, N′-tetraglycidyl-m-xylenediamine, Tetrad (registered trademark) X manufactured by Mitsubishi Gas Chemical Company, Inc.
Curing agent B2-2: EX-512 (chemical name: polyglycerol polyglycidyl ether), manufactured by Nagase ChemteX Corporation

  In Examples 1-16, all the obtained polyester-type adhesives showed the favorable adhesive force to a base material, and the peeling state was also interface peeling. Further, even after heating at 150 ° C., the peeled state was interfacial peeling, and the holding power was good even in a high temperature environment. Moreover, transparency was also high and the performance which was excellent as an adhesive was shown.

  In Example 7 and Example 8, the obtained polyester-based pressure-sensitive adhesives all showed good adhesive force to the substrate, and the peeled state was also interfacial peeling. Moreover, even after 150 degreeC heating, the peeling state was interface peeling. The holding force slightly shifted only in a high temperature environment. The reason is presumed that there are few crosslinking points with the added isocyanate because the copolymerized polyester segment does not contain branches.

  In Example 5 and Example 6, although the copolyester segment does not contain a branch, all of the obtained polyester-based pressure-sensitive adhesives show a good adhesive force to the substrate, and the peeled state is also an interface. It was peeling. Further, even after heating at 150 ° C., the peeled state was interfacial peeling, and the holding power was good even in a high temperature environment. Moreover, transparency was also high and the performance which was excellent as an adhesive was shown. In Example 5 and Example 6, since there are many compounding quantities of a hardening | curing agent, it is thought that holding power was favorable also in a high temperature environment.

  In Examples 13 to 15, although the copolymer polyester segment does not contain a branch, all the obtained polyester-based pressure-sensitive adhesives show a good adhesive force to the base material, and the peeling state is also interfacial peeling. there were. Further, even after heating at 150 ° C., the peeled state was interfacial peeling, and the holding power was good even in a high temperature environment. Moreover, transparency was also high and the performance which was excellent as an adhesive was shown. In Examples 13 to 15, since an epoxy curing agent having excellent heat resistance is used, it is considered that the holding power was good even in a high temperature environment.

  In Comparative Example 1 and Comparative Example 2, although the adhesive force to the base material A was high, an adhesive having poor adhesiveness to other base materials was obtained. In addition, the holding power at high temperatures was poor, and the transparency of the pressure-sensitive adhesive was slightly poor. It is considered that the polyester resin contained in the pressure-sensitive adhesive crystallized and the adhesion to the base material deteriorated.

  In Comparative Example 3, an adhesive having poor heat resistance and holding power at a high temperature was obtained although the adhesive strength to the substrate was moderate. The polyester resin contained in the pressure-sensitive adhesive does not have a block structure and contains almost no aromatic dicarboxylic acid component in the composition. Therefore, it is considered that the mechanical strength deteriorated.

  In Comparative Example 4, a pressure-sensitive adhesive having poor adhesion to other substrates was obtained although the adhesion to substrate A was moderate. In addition, the holding power at high temperature was poor, and the transparency of the adhesive was low. It is considered that the polyester resin contained in the pressure-sensitive adhesive crystallizes and the adhesiveness to the base material has deteriorated.

  In Comparative Example 5 and Comparative Example 6, although the adhesiveness to all the substrates was excellent, an adhesive having inferior peeling state after the heat resistance test and holding power at high temperature was obtained. It is considered that the acrylic resin contained in the pressure-sensitive adhesive contains many acrylic monomers and low-molecular acrylic oligomers.

  In the comparative example 7, it was not able to bond to all the base materials, and evaluation as an adhesive was not able to be performed. This is probably because the polyester resin does not contain an aliphatic segment, so that the glass transition point is high and the resin cannot be used as an adhesive.

  In Comparative Example 8, the adhesiveness to all the substrates was obtained, but the adhesive strength was inferior. Moreover, it became an adhesive with inferior holding power at high temperatures. This is probably because the copolyester segment of the polyester resin has a low glass transition temperature, so that the cohesive force as an adhesive is insufficient.

  In Comparative Examples 9, 10 and Comparative Example 12, an adhesive having poor adhesion to the substrate was obtained. In addition, the retention at high temperatures was poor. It is considered that the polyester resin contained in the pressure-sensitive adhesive crystallizes and the adhesiveness to the base material has deteriorated. Further, since the amount of the aromatic dicarboxylic acid contained in the composition of the polyester resin is small, it is considered that the mechanical strength is lowered and the heat resistance at high temperature is deteriorated.

  In Comparative Example 11, although the adhesive force to the base material was moderate, adhesive residue was generated at the time of peeling from the base material A, and an adhesive having inferior heat resistance and holding power at high temperature was obtained. The polyester resin contained in the pressure-sensitive adhesive does not have a block structure and contains almost no aromatic dicarboxylic acid component in the composition. Therefore, it is considered that the mechanical strength deteriorated.

  In Comparative Example 13 and Comparative Example 17, the adhesive force to all base materials was almost zero. It is considered that the polyester resin contained in the adhesive could not be used as an adhesive because of its high glass transition temperature.

  In Comparative Example 14, a pressure-sensitive adhesive having a good holding power at high temperatures was obtained although the pressure-sensitive adhesive force to the substrate was good. This is probably because the copolyester segment of the polyester resin had a low glass transition temperature and became an adhesive having poor cohesion.

  In Comparative Example 15 and Comparative Example 16, although the adhesion to all the substrates was excellent, an adhesive having a poor peeled state after the heat resistance test and a high holding force at high temperatures was obtained. It is considered that the acrylic resin contained in the pressure-sensitive adhesive contains many acrylic monomers and low-molecular acrylic oligomers.

  In Comparative Example 18, adhesion to all the substrates was obtained, but the adhesive strength was inferior. Moreover, it became an adhesive with inferior holding power at high temperatures. This is probably because the copolyester segment of the polyester resin has a low glass transition temperature, so that the cohesive force as an adhesive is insufficient.

  As is clear from Examples 1 to 16 and Comparative Examples 1 to 18, it can be seen that the polyester-based pressure-sensitive adhesive of the present invention is excellent in adhesive strength, heat resistance, holding power, and transparency.

  The polyester-based resin used in the present invention is useful as a resin raw material for the pressure-sensitive adhesive, and the pressure-sensitive adhesive containing such a polyester-based resin is excellent in properties such as adhesive strength and heat resistance, holding power, and transparency. It can be suitably used as an adhesive in the optical field.

Claims (4)

A pressure-sensitive adhesive containing a polyester resin (A) satisfying the following (1) to (3) and a curing agent (B).
(1) The polyester resin (A) is a block polyester resin containing a copolymerized polyester segment (a) and an aliphatic segment (b). (2) As a copolymerization component of the copolymerized polyester segment (a), a polyvalent carboxylic acid is used. The glass transition temperature of the (3) copolymer polyester segment (a) containing an acid component and a polyhydric alcohol component is 15 ° C. or higher.   The pressure-sensitive adhesive according to claim 1, wherein the copolymerized polyester segment (a) includes a branched structure.   The polyester resin (A) contains 10 to 200 ppm of at least one compound selected from the group consisting of an Al compound, a Ge compound, a Ti compound, and a Zn compound. The adhesive as described in.   A pressure-sensitive adhesive sheet comprising a layer made of the pressure-sensitive adhesive according to claim 1 on one side or both sides of a support.