JP2018193537A - Polyester-based adhesive and its adhesive sheet - Google Patents

Abstract

To provide a polyester-based adhesive which is excellent in characteristics such as adhesive force, heat resistance, holding power and transparency and is used for a label, an adhesive tape, a sheet or the like.SOLUTION: There is provided an adhesive which comprises a polyester resin (A) containing a polyvalent carboxylic acid component and a polyvalent alcohol component as copolymerization components which satisfies the following (1) to (5) and a curing agent (B): (1) when the content of the polyvalent carboxylic acid component is defined as 100 mol%, the content of an aromatic dicarboxylic acid component is 10 mol% or more, (2) when the content of the polyvalent alcohol component is defined as 100 mol%, the content of a glycol component having a hydrocarbon group in the side chain is 10 mol% or more, (3) when the total content of the polyvalent carboxylic acid component and the polyvalent alcohol component is defined as 200 mol%, the total content of a dicarboxylic acid component having an odd number of carbon atoms in the main chain and glycol is 30 mol% or more, (4) when the total content of the polyvalent carboxylic acid component and the polyvalent alcohol component is defined as 200 mol%, the content of a dicarboxylic acid component having an even number of carbon atoms in the main chain and glycol is 30 mol% or less and (5) the polyester resin (A) has a number average molecular weight of 10000 or more.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.

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

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

  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.

  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 comprising a polyester resin (A) satisfying the following (1) to (5) and a curing agent (B), wherein a polyvalent carboxylic acid component and a polyhydric alcohol component are used as a copolymerization component.
(1) When the polyvalent carboxylic acid component is 100 mol%, the content of the aromatic dicarboxylic acid component is 10 mol% or more. (2) When the polyhydric alcohol component is 100 mol%, the side chain is carbonized. The content of the glycol component having a hydrogen group is 10 mol% or more. (3) When the total of the polyvalent carboxylic acid component and the polyhydric alcohol component is 200 mol%, the dicarboxylic acid component having an odd number of carbon atoms in the main chain (4) When the total of the polycarboxylic acid component and the polyhydric alcohol component is 200 mol%, the dicarboxylic acid component having an even number of carbon atoms in the main chain and the glycol (5) The polyester resin (A) has a number average molecular weight of 10,000 or more.

  The dicarboxylic acid component having an odd main chain carbon number is preferably azelaic acid, and the glycol having an odd main chain carbon number is preferably 1,5-pentanediol.

  The glass transition temperature of the polyester resin (A) is −20 ° C. or lower, the polyester resin (A) contains a branched structure, and the polyester resin (A) contains an Al compound, a Ge compound, a Ti compound, or a Zn compound. It is preferable to contain 10-200 ppm.

  A pressure-sensitive adhesive sheet comprising a layer made of the above-mentioned 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 polyester resin satisfying the following (1) to (5) using a polyvalent carboxylic acid component and a polyhydric alcohol component as a copolymerization component. That is, the polyester resin (A) is a polyester resin having a chemical structure obtained by polycondensation of a carboxylic acid component composed of a divalent or higher polyvalent carboxylic acid compound and an alcohol component composed of a divalent or higher polyhydric alcohol compound. It is preferable that at least one of the polyvalent carboxylic acid compound and the polyhydric alcohol compound is a copolyester resin composed of two or more kinds of components. 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 the molar basis with respect to the total of all acid components and all alcohol components constituting the polyester resin (A) used in the present invention. It is preferable that 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.

<Requirement (1)>
When the polyvalent carboxylic acid component is 100 mol%, the content of the aromatic dicarboxylic acid component needs to be 10 mol% or more. Preferably it is 12 mol% or more, More preferably, it is 15 mol% or more. When it is less than 10 mol%, the mechanical strength of the resulting pressure-sensitive adhesive may be lowered, and sufficient adhesive strength may not be obtained. Although an upper limit is not specifically limited, It is preferable that it is 70 mol% or less, More preferably, it is 60 mol% or less. If the amount is too large, the glass transition temperature becomes high and sufficient adhesive strength may not be obtained.

  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.

<Requirement (2)>
When the polyhydric alcohol component is 100 mol%, the content of the glycol component having a hydrocarbon group in the side chain needs to be 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.

  The glycol component is preferably an aliphatic glycol having a hydrocarbon group in the side chain. 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, the initial adhesive force is not lowered due to the crystallinity of the copolyester, and further, the hydrolysis resistance of the copolyester resin can be expected to be improved.

  Specific examples of the glycol component having a hydrocarbon group in the side chain are not particularly limited, but 1,2-propanediol, 2-methyl-1,3-propanediol (hereinafter also referred to as 2MG), 2,2- Dimethyl-1,3-propanediol (hereinafter also referred to as neopentyl glycol or NPG), 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- Examples include pentanediol and 3,3-dimethyl-1,5-pentanediol. These 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.

<Requirement (3)>
When the total of the polycarboxylic acid component and the polyhydric alcohol component is 200 mol%, the total content of the dicarboxylic acid component having an odd number of carbon atoms in the main chain and the glycol needs to be 30 mol% or more. . Preferably it is 40 mol% or more, More preferably, it is 50 mol% or more. When the amount is less than 30 mol%, the tackiness of the obtained pressure-sensitive adhesive may be lowered, and sufficient adhesive strength may not be obtained. Although an upper limit is not specifically limited, It is preferable that it is 180 mol% or less, More preferably, it is 150 mol% or less. If the amount is too large, the hydrolysis resistance may deteriorate, or the mechanical properties of the resin may deteriorate. Here, for the introduction of a carboxyl group, when an acid anhydride or the like is post-added (post-addition) after polymerization of the polyester resin, the total amount of the polyvalent carboxylic acid component and the polyhydric alcohol component may exceed 200 mol%. In this case, the total amount of the composition excluding the component to which acid anhydride or the like is post-added (post-addition) is calculated as 200 mol%.

  The dicarboxylic acid component having an odd main chain carbon number is preferably an aliphatic dicarboxylic acid having an odd main chain carbon number, and an aliphatic dicarboxylic acid having an odd main chain carbon number having no side chain. More preferably. Here, the main chain refers to a hydrocarbon group (carbon chain) connecting two carboxyl groups, and the carbon number of the main chain refers to the carbon number of the hydrocarbon group excluding the carbon of the carboxyl group. The side chain means a hydrocarbon group branched from the main chain. When the number of carbon atoms in the main chain is an odd number, crystallization of the polyester resin (A) is difficult to occur, and excellent adhesive strength can be expressed. Moreover, the adhesive force can be further improved by having no side chain.

  Specific examples of the dicarboxylic acid component having an odd number of carbon atoms in the main chain include, but are not limited to, malonic acid (propanedioic acid), glutaric acid (1,3-propanedicarboxylic acid), pimelic acid (1,5-pentane) Dicarboxylic acid), azelaic acid (1,7-heptanedicarboxylic acid), 1,9-nonanedicarboxylic acid. These dicarboxylic acid components having an odd number of carbon atoms in the main chain can be used alone or in combination of two or more. Of these, azelaic acid is most preferable from the viewpoints of suppression of crystallization, adhesive strength, and cost.

  The glycol component having an odd number of carbon atoms in the main chain is preferably an aliphatic glycol having an odd number of carbon atoms in the main chain, more preferably an aliphatic glycol having an odd number of carbon atoms in the main chain having no side chain. preferable. Here, the main chain refers to a hydrocarbon group (carbon chain) connecting two hydroxyl groups, and the side chain refers to a hydrocarbon group branched from the main chain. When the number of carbon atoms in the main chain is an odd number, crystallization of the polyester resin (A) is difficult to occur, and excellent adhesive strength can be expressed. Moreover, the adhesive force can be further improved by having no side chain.

  Specific examples of the glycol component having an odd number of carbon atoms in the main chain include, but are not limited to, methanediol, 1,3-propanediol, 1,5-pentanediol, 1,7-heptanediol, 1,9-nonane. Diols are mentioned. These glycol components having an odd number of carbon atoms in the main chain can be used alone or in combination of two or more. 1,5-pentanediol is preferred.

  The dicarboxylic acid component having an odd number of carbon atoms in the main chain and the glycol component having an odd number of carbon atoms in the main chain may be used alone or in combination as long as the total content is 30 mol% or more. It doesn't matter. Particularly preferably, an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid having an odd number of carbon atoms in the main chain are used in combination.

<Requirement (4)>
When the total of the polycarboxylic acid component and the polyhydric alcohol component is 200 mol%, the total content of the dicarboxylic acid component having an even number of carbon atoms in the main chain and the glycol must be 30 mol% or less. . Preferably it is 20 mol% or less, More preferably, it is 10 mol% or less, More preferably, it is 5 mol% or less, and it may be 0 mol%. When it exceeds 30 mol%, crystallization of the polyester resin (A) occurs, and the tackiness may be lowered.

  The dicarboxylic acid component having an even number of carbon atoms in the main chain is preferably an aliphatic dicarboxylic acid having an even number of carbon atoms in the main chain, and is an aliphatic dicarboxylic acid having an even number of carbon atoms in the main chain having no side chain. It is more preferable. The main chain and the side chain are as defined above.

  Specific examples of the dicarboxylic acid component having an even number of carbon atoms in the main chain are not particularly limited, but succinic acid (butanedioic acid), adipic acid (1,4-butanedicarboxylic acid), suberic acid (1,6-hexane) Dicarboxylic acid) and sebacic acid (1,8-octanedicarboxylic acid). These dicarboxylic acid components having an even number of carbon atoms in the main chain can be used alone or in combination of two or more.

  Specific examples of the glycol component having an even number of main chain carbon atoms include, but are not limited to, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, and 1,10-decanediol. It is done. These glycol components having an even number of carbon atoms in the main chain can be used alone or in combination of two or more. In the present invention, since ethylene glycol has a small effect of promoting crystallization, it is not included in the glycol component having an even number of carbon atoms in the main chain.

  The dicarboxylic acid component having an even number of carbon atoms in the main chain and the glycol component having an even number of carbon atoms in the main chain may be used alone or in combination as long as the total content is 30 mol% or less. I do not care.

<Other polycarboxylic acid and polyhydric alcohol components>
Other polyvalent carboxylic acids include aromatic oxycarboxylic acids such as p-oxybenzoic acid and p- (hydroxyethoxy) benzoic acid; fumaric acid, maleic acid, itaconic acid, hexahydrophthalic acid, tetrahydrophthalic acid and the like. Unsaturated carboxylic acids of the above; alicyclic dicarboxylic acids such as 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, and the like can also be used. 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 formation of a three-dimensional structure may occur during polymerization of the polyester resin (A), resulting in a resin insoluble in the solvent (C).

  Other polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1 1,4-cyclohexanedimethanol, tricyclodecanediol, ethylene oxide adduct and propylene oxide adduct of bisphenol A, ethylene oxide adduct and propylene oxide adduct of hydrogenated bisphenol A, and the like 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).

<Requirement (5)>
The number average molecular weight of the polyester resin (A) needs to be 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. When the number average molecular weight is too large, the isocyanate curing agent (B) cannot be sufficiently reacted, so that the heat resistance and heat-and-moisture resistance may be lowered.

  The number average molecular weight of the present invention is 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 −20 ° 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 −20 ° 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) 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) containing a branched structure has an increased reactivity with the isocyanate curing agent (B), it becomes a preferred resin when used as an adhesive.

  The amount of the copolymer component containing the branched structure of the polyester resin (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 formation of a three-dimensional structure may occur during polymerization of the polyester resin (A), resulting in a resin insoluble in the solvent (C).

As a method for producing the polyester resin (A), a known method can be employed. For example, the target polyester resin 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. 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) 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 polymerizing a polyester resin, 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 a polyester oligomer and then polymerized by a polycondensation reaction under reduced pressure. And a method of introducing a carboxyl group into the polyester resin. 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, or 2-sulfo-1,4-butanediol, 2,5- By copolymerizing a dicarboxylic acid or glycol containing a sulfonic acid metal base such as a metal salt such as dimethyl-3-sulfo-2,5-hexanediol, the sulfonic acid metal base can be easily introduced.

  The polyester resin (A) may contain a block component by ring-opening polymerization. After polymerizing the polyester resin under reduced pressure, a block component by ring-opening polymerization can be introduced by adding a ring-opening polymerizable monomer under normal pressure and nitrogen atmosphere. Examples of such ring-opening polymerizable monomers include cyclic esters, cyclic carbonates, cyclic amides, and the like.

  Examples of cyclic esters include lactide, β-propiolactone, β-butyrolactone, γ-butyrolactone, γ-hexanolactone, γ-octanolactone, δ-valerolactone, δ-hexalanolactone, δ-octanolactone, Examples thereof include aliphatic lactones such as ε-caprolactone, δ-dodecanolactone, α-methyl-γ-butyrolactone, β-methyl-δ-valerolactone, glycolide, and lactide. In particular, lactide and ε-caprolactone are preferable from the viewpoint of reactivity and availability.

  The ring-opening polymerizable monomers can be used alone or in admixture of several kinds.

  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.

  Any polycondensation catalyst used in the polymerization of the polyester resin (A) may be used, and examples thereof include Al compounds, Sb compounds, Ge compounds, Ti compounds, and 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 an Al compound, a Ge compound, a Ti compound or a Zn compound. More preferably, it is 10-100 ppm.

The composition and composition ratio of the polyester resin (A) can be determined by calculation from an integral ratio of ¹ H-NMR measured by dissolving the polyester resin (A) in a solvent such as deuterated chloroform.

  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 wt. % Or more is preferable. More preferably, it is 50 weight% or more. If the solvent-insoluble component after the crosslinking treatment of the polyester resin (A) is less than 40% by weight, the cohesive force of the pressure-sensitive adhesive is insufficient, the mechanical strength is lowered, and sufficient heat resistance may not be obtained. Moreover, it is preferable that the upper limit of a solvent insoluble component is 85 weight%, More preferably, it is 75 weight% or less. When the solvent-insoluble content after the crosslinking treatment of the polyester resin (A) exceeds 85% by weight, the flexibility of the crosslinked body of the polyester resin (A) is impaired, and the tackiness tends to be lowered.

Moreover, the storage elastic modulus (23 ° C.) after the crosslinking treatment of the polyester resin (A) is not particularly limited, but for example, preferably 1 × 10 ⁶ Pa or less, more preferably 6 × 10 ⁵ Pa or less. It is. 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 isocyanate curing agent (B), but dissolves the polyester resin (A) and the isocyanate curing agent (B). An organic solvent is preferred. 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 an isocyanate 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) The composition and composition ratio of the polyester resin (A) were determined by ¹ H-NMR measurement (proton nuclear magnetic resonance spectroscopy) with a resonance frequency of 400 MHz. 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)
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). A sample (polyester resin (A)) 5 mg 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. The case where the deviation was less than 1 mm, the case where the deviation was less than 1 mm and less than 25 mm, the distance displaced was described, and the case where the adhesive sheet dropped from the stainless steel plate was marked as 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, 65 parts by mass of terephthalic acid, 59 parts by mass of isophthalic acid, 244 parts by mass of azelaic acid Part, trimellitic anhydride 4 parts by mass, ethylene glycol 124 parts by mass, 2,2-dimethyl 1,3-propanediol 208 parts by mass and tetrabutyl titanate 1 part by mass, while heating up to 230 ° C. over 4 hours The esterification reaction was performed. After completion of the esterification reaction, the pressure in the system was reduced to 10 torr over 30 minutes while the temperature was raised to 240 ° C., and the pressure was further reduced to 1 torr or less under vacuum to carry out a polycondensation reaction at 240 ° C. for 30 minutes. Thereafter, the polycondensation reaction was terminated by flowing nitrogen into the system and breaking the vacuum. After completion of the reaction, the polyester resin was taken out and cooled to obtain a polyester resin (A-1). As a result of NMR analysis, the obtained polyester resin (A-1) has a carboxylic acid component in a molar ratio of terephthalic acid / isophthalic acid / azelineic acid / trimellitic acid = 19/15/65/1, and a glycol component in a molar ratio. The ratio was ethylene glycol / 2,2-dimethyl 1,3-propanediol = 40/60. The measurement results are shown in Table 1 together with other resin physical properties.

Synthesis of polyester resins (A-2) to (A-10) Polyester resins (A-2) to (A) whose compositions are the polyester resins shown in Table 1 in the same manner as in the synthesis example of polyester resin (A-1) -10) 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-11) In a reaction can equipped with a stirrer, a thermometer, a heater, a cooling device, and a condenser for distillation, 63 parts by mass of terephthalic acid, 50 parts by mass of isophthalic acid, and 244 parts by mass of azelaic acid Part, trimellitic anhydride 4 parts by mass, ethylene glycol 124 parts by mass, 2,2-dimethyl 1,3-propanediol 208 parts by mass and tetrabutyl titanate 1 part by mass, while heating up to 230 ° C. over 4 hours The esterification reaction was performed. After completion of the esterification reaction, the pressure in the system was reduced to 10 torr over 30 minutes while the temperature was raised to 240 ° C., and the pressure was further reduced to 1 torr or less under vacuum to carry out a polycondensation reaction at 240 ° C. for 30 minutes. Thereafter, the polycondensation reaction was terminated by flowing nitrogen into the system and breaking the vacuum. Then, it cooled until the internal temperature became 220 degreeC, flowing nitrogen into the system. After cooling, 2 parts by weight of succinic anhydride was added, filled with nitrogen again, and acid addition reaction was performed at 220 ° C. for 30 minutes. After completion of the reaction, the polyester resin was taken out and cooled to obtain a polyester resin (A-1). As a result of NMR analysis, the obtained polyester resin (A-1) has a carboxylic acid component in a molar ratio of terephthalic acid / isophthalic acid / azelineic acid / trimellitic acid = 19/15/65/1, and a glycol component in a molar ratio. The ratio was ethylene glycol / 2,2-dimethyl-1,3-propanediol = 40/60, and the added acid component was succinic anhydride = 1 in molar ratio. The measurement results are shown in Table 2 together with other resin physical properties.

Synthesis of polyester resins (A-12) to (A-20) Polyester resins (A-12) to (A) whose compositions are the polyester resins shown in Table 2 in the same manner as in the synthesis example of polyester resin (A-11) -20) 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-21) 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 added, and nitrogen was passed through the system, and the temperature was raised to 80 ° C. The radical polymerization reaction was carried out for 4 hours. Table 3 shows the measurement results together with the charged composition and the resin physical properties in the weight ratio of the obtained acrylic resin.

Synthesis of Acrylic Resin (A-22) An acrylic resin (A-22), 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-21). 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 to 18 and Comparative Examples 1 to 12, the obtained polyester resin and acrylic resin were dissolved in ethyl acetate so that the solid concentration was 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 11-12, 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 or epoxy was added according to the amounts in Tables 5 and 6. A curing agent was blended into 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 1-18, all 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 Comparative Examples 1 and 7, adhesives having high adhesion to the substrate A but poor in adhesion to other substrates were obtained. 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 crystallized and the adhesion to the base material deteriorated.

  In Comparative Examples 2 and 8, an adhesive having poor adhesiveness to the substrate B was obtained although the adhesive force to the substrate A and the substrate C was moderate. Since the composition of the polyester resin contained in the pressure-sensitive adhesive contains almost no aromatic dicarboxylic acid component, it is considered that the mechanical strength deteriorated.

  In Comparative Examples 3 and 9, pressure-sensitive adhesives having poor adhesion to all substrates were obtained. 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 Examples 4 and 10, although the adhesiveness to all the substrates was excellent, a pressure-sensitive adhesive having inferior peeling state after the heat resistance test and holding power at high temperature was obtained. Since the molecular weight of the polyester resin contained in the pressure-sensitive adhesive is low, it is considered that a sufficient cured product cannot be formed with the isocyanate curing agent.

  In Comparative Examples 5, 6, 11, and 12, adhesives that were inferior in the peeled state after the heat resistance test and the holding power at high temperatures were obtained, although the adhesion to all the substrates was excellent. It is considered that the acrylic resin contained in the pressure-sensitive adhesive contains many acrylic monomers and low-molecular acrylic oligomers.

  As is clear from Examples 1 to 18 and Comparative Examples 1 to 12, 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 (7)

A pressure-sensitive adhesive comprising a polyester resin (A) satisfying the following (1) to (5) and a curing agent (B), wherein a polyvalent carboxylic acid component and a polyhydric alcohol component are used as a copolymerization component.
(1) When the polyvalent carboxylic acid component is 100 mol%, the content of the aromatic dicarboxylic acid component is 10 mol% or more. (2) When the polyhydric alcohol component is 100 mol%, the side chain is carbonized. The content of the glycol component having a hydrogen group is 10 mol% or more. (3) When the total of the polyvalent carboxylic acid component and the polyhydric alcohol component is 200 mol%, the dicarboxylic acid component having an odd number of carbon atoms in the main chain (4) When the total of the polycarboxylic acid component and the polyhydric alcohol component is 200 mol%, the dicarboxylic acid component having an even number of carbon atoms in the main chain and the glycol (5) The polyester resin (A) has a number average molecular weight of 10,000 or more.   The pressure-sensitive adhesive according to claim 1, wherein the dicarboxylic acid component having an odd number of carbon atoms in the main chain is azelaic acid.   The pressure-sensitive adhesive according to claim 1 or 2, wherein the glycol having an odd number of carbon atoms in the main chain is 1,5-pentanediol.   The pressure-sensitive adhesive according to any one of claims 1 to 3, wherein the polyester resin (A) has a glass transition temperature of -20 ° C or lower.   The pressure-sensitive adhesive according to claim 1, wherein the polyester resin (A) includes a branched structure.   The pressure-sensitive adhesive according to any one of claims 1 to 5, wherein the polyester resin (A) contains 10 to 200 ppm of an Al compound, a Ge compound, a Ti compound, or a Zn compound.   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.