JP2019172810A - Copolymerized polyester resin and adhesive composition containing the same - Google Patents

Abstract

To provide a polyester-based adhesive that is excellent in all of adhesive strength, heat resistance, holding power and transparency, and is used for a label, an adhesive tape or a sheet and the like.SOLUTION: Provided is a copolymerized polyester resin (A) satisfying the following (1) to (5). (1) a polyvalence carboxylic acid component and a polyhydric alcohol component are used as a copolymerization component. (2) when the polyvalent carboxylic acid component of the copolymerized polyester resin (A) is 100 mol%, the content of aromatic dicarboxylic acid component is 30 mol% or less. (3) When the polyvalent carboxylic acid component of the copolymerized polyester resin (A) is 100 mol%, the content of alicyclic dicarboxylic acid component is 40 mol% or more. (4) When the polyhydric alcohol component of the copolymerized polyester resin (A) is 100 mol%, the content of the glycol component having a hydrocarbon group in the side chain is 30 mol% or more. (5) the number average molecular weight of the copolymerized polyester resin (A) is in the range of 2500 or more and less than 15000.SELECTED DRAWING: None

Description

  The present invention relates to a polyester-based pressure-sensitive adhesive composition. Specifically, the present invention relates to a polyester-based pressure-sensitive adhesive composition excellent in adhesiveness, heat resistance, holding power and transparency, and a pressure-sensitive adhesive sheet provided with a layer comprising the pressure-sensitive adhesive composition.

  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.

  Acrylic adhesives are required to have adhesion to various substrates. For example, for polar substrates such as polyester and stainless steel, it is generally known that acrylic acid is copolymerized to increase adhesion. It has been.

  For non-polar substrates such as polypropylene and polyolefin, an adhesive mainly composed of acrylate monomers having a long-chain hydrocarbon group is used as in Patent Document 3, but polar substrates and non-polar substrates It has been difficult to design a pressure-sensitive adhesive having good adhesion to both using only the acrylate monomer of the acrylic resin composition.

  In order to solve this problem, for example, Patent Document 4 discusses an acrylic pressure-sensitive adhesive containing a rosin ester-based additive. Rosin ester-based additives have good compatibility with acrylic resins, so it is possible to improve adhesion to various substrates while maintaining the transparency of the adhesive, and nonpolar groups such as polypropylene and polyolefin. It is possible to show good adhesion to the material.

Japanese Patent No. 2672308 Japanese Patent No. 4868654 JP-A-9-188854 JP 2009-227925 A

  However, since the rosin ester compound has a poor reaction point with the curing agent in the pressure-sensitive adhesive and it is difficult to form a high-density cured body, the heat resistance may be lowered at a temperature exceeding the softening point of the rosin ester. there were.

  The rosin ester compound is deposited on the surface of the pressure-sensitive adhesive to increase the adhesion to the adherend. However, since the rosin ester compound itself is a hard compound, the ball tack decreases at room temperature. In some cases, there was a problem of zipper peel at the time of peeling. Furthermore, there was a problem that coloring was likely to occur due to poor weather resistance.

  The object of the present invention is to solve the above-mentioned problems that conventional acrylic adhesives and rosin ester compounds have. That is, an object of the present invention is to provide a pressure-sensitive adhesive composition used for a label, a pressure-sensitive adhesive tape, a sheet, or the like having excellent adhesiveness, heat resistance, holding power and transparency characteristics.

  As a result of intensive studies to solve the above problems, the present inventor has found that an adhesive composition with significantly improved adhesiveness, heat resistance, holding power, and transparency can be obtained by the following method. The invention has been completed. That is, the present invention has the following configuration.

Copolyester resin (A) that satisfies the following (1) to (5).
(1) A polyvalent carboxylic acid component and a polyhydric alcohol component are used as a copolymerization component.
(2) When the polyvalent carboxylic acid component of the copolymerized polyester resin (A) is 100 mol%, the content of the aromatic dicarboxylic acid component is 30 mol% or less.
(3) When the polyvalent carboxylic acid component of the copolymerized polyester resin (A) is 100 mol%, the content of the alicyclic dicarboxylic acid component is 40 mol% or more.
(4) When the polyhydric alcohol component of the copolymerized polyester resin (A) is 100 mol%, the content of the glycol component having a hydrocarbon group in the side chain is 30 mol% or more.
(5) The number average molecular weight of the copolyester resin (A) is in the range of 2500 or more and less than 15000.

  In the copolymerized polyester resin (A), the alicyclic dicarboxylic acid component is preferably 1,4-cyclohexanedicarboxylic acid, hexahydrophthalic anhydride or 1,2-cyclohexanedicarboxylic acid, and has a hydrocarbon group in the side chain. The glycol component is preferably 2,2-dimethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, propylene glycol or 3-methylpentanediol. Further, it preferably includes a branched structure.

  The adhesive composition containing the copolyester resin (A) in any one of the said, an acrylic resin (B), and a hardening | curing agent (C).

  The copolymerized polyester resin (A) of the present invention is a copolymerized polyester resin having a specific structure and physical properties. Therefore, the pressure-sensitive adhesive composition containing the copolyester resin (A), the acrylic resin (B), and the curing agent (C) exhibits sufficient adhesive strength at a pressure of about a finger pressure, and has heat resistance and holding power. In addition, it has an excellent effect on transparency.

<Copolymerized polyester resin (A)>

  Hereinafter, the copolyester resin (A) of the present invention will be described. The copolymerized polyester resin (A) in the present invention satisfies the following (1) to (5).

<Requirement (1)>
The copolyester resin (A) is a copolyester 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 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. 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 each of the dicarboxylic acid component and the glycol component is 50 mol% on a molar basis with respect to the total of all the polyvalent carboxylic acid components and all the polyhydric alcohol components constituting the copolyester resin (A). It is preferable to occupy the above. The total of each 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 even if it is 100 mol%. There is no problem.

  Although it does not specifically limit as a polyvalent carboxylic acid component which comprises the copolyester resin (A) of this invention, A terephthalic acid, isophthalic acid, orthophthalic acid, naphthalene dicarboxylic acid, 4,4'- dicarboxybiphenyl, 5 -Aromatic dicarboxylic acids such as sodium sulfoisophthalic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 2,5-norbornenedicarboxylic acid, tetrahydrophthalic acid alicyclic ring Dicarboxylic acid, oxalic acid, malonic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, octadecanedioic acid, fumaric acid, maleic acid, itaconic acid, mesaconic acid, citraconic acid, etc. Aliphatic dicarboxylic acids can be exemplified.

  Further, if necessary, trimellitic acid, trimesic acid, pyromellitic acid and the like, and tricarboxylic acid and anhydride thereof may be included. These carboxylic acids can be used alone or in combination of two or more. These trivalent or higher polyvalent carboxylic acid components are preferably 5 mol% or less, more preferably 4 mol% or less, and even more preferably 3 mol% when the total polyvalent carboxylic acid component is 100 mol%. It is less than mol%. If the amount is too large, gelation due to the formation of a three-dimensional structure may occur during the polymerization of the copolyester resin (A).

  Although it does not specifically limit as a polyhydric alcohol component which comprises the copolyester resin (A) of this invention, Ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-amino-2-ethyl-1,3- Propanediol, 2-amino-2-methyl-1,3-propanediol, 2-ethyl-2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, neopentyl Glycol, 3-methyl-1,5-pentanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8- Kutanjioru, 1,9-nonanediol, 1,10-decanediol, tricyclodecane dimethanol, diethylene glycol, triethylene glycol, dipropylene glycol, and aliphatic glycols such as tripropylene glycol. Also, bisphenol A, bisphenol S, bisphenol C, bisphenol Z, bisphenol AP and 4,4′-biphenol ethylene oxide adduct or propylene oxide adduct, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, Mention may be made of alicyclic glycols such as 1,4-cyclohexanedimethanol, and polyalkylene ether glycols such as polyethylene glycol and polypropylene glycol.

  Further, if necessary, 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 trihydric or higher polyhydric alcohol components are preferably 5 mol% or less, more preferably 4 mol% or less, and even more preferably 3 mol% when the total polyhydric alcohol component is 100 mol%. It is as follows. If the amount is too large, gelation due to the formation of a three-dimensional structure may occur during the polymerization of the copolyester resin (A).

<Requirement (2)>
When the polyvalent carboxylic acid component of the copolymerized polyester resin (A) is 100 mol%, the content of the aromatic dicarboxylic acid component is 30 mol% or less. Preferably it is 25 mol% or less, More preferably, it is 20 mol% or less, More preferably, it is 15 mol% or less, Especially preferably, it is 10 mol% or less, Most preferably, it is 5 mol% or less. The lower limit is not particularly limited, and it may be 0 mol%, but 1 mol% may be contained. If it exceeds 30 mol%, the compatibility with the acrylic resin (B) may deteriorate, and the transparency of the pressure-sensitive adhesive composition may deteriorate.

  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 (3)>
When the polyvalent carboxylic acid component of the copolymerized polyester resin (A) is 100 mol%, the content of the alicyclic dicarboxylic acid component is 40 mol% or more. Preferably it is 45 mol% or more, More preferably, it is 50 mol% or more, Especially preferably, it is 60 mol% or more, Most preferably, it is 70 mol% or more. The upper limit is not particularly limited and may be 100 mol%, but is preferably 99 mol% or less, more preferably 95 mol% or less, still more preferably 90 mol% or less, and particularly preferably. It is 85 mol% or less. When the content of the alicyclic dicarboxylic acid component is less than 40 mol%, the mechanical strength of the copolyester resin (A) is insufficient, and the adhesiveness and heat resistance of the pressure-sensitive adhesive composition may be insufficient.

  The alicyclic dicarboxylic acid component is not particularly limited, but is unsaturated alicyclic dicarboxylic acid such as hexahydrophthalic anhydride and tetrahydrophthalic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1, Examples include 4-cyclohexanedicarboxylic acid. These alicyclic dicarboxylic acid components can be used alone or in combination of two or more. 1,4-cyclohexanedicarboxylic acid, hexahydrophthalic anhydride or 1,2-cyclohexanedicarboxylic acid is preferred.

<Requirement (4)>
When the polyhydric alcohol component of the copolyester resin (A) is 100 mol%, the content of the glycol component having a hydrocarbon group in the side chain is 30 mol% or more. Preferably it is 40 mol% or more, More preferably, it is 50 mol% or more. The upper limit is not particularly limited and may be 100 mol%, but is preferably 99 mol% or less, more preferably 95 mol% or less, and still more preferably 90 mol% or less. When the content of the glycol component having a hydrocarbon group in the side chain is less than 30 mol%, an acrylic (meth) acrylate having an alkyl group having 4 to 18 carbon atoms is used as a main raw material among the acrylic resin (B). The compatibility with the obtained acrylic resin may deteriorate, and the transparency of the pressure-sensitive adhesive composition may deteriorate.

  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. The total number of carbon atoms in the side chain is preferably 1 to 4, and more preferably 2 to 3. Moreover, it is preferable that carbon number of a main chain is 1-10, More preferably, it is 2-8, More preferably, it is 3-5. 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.

  The glycol component having a hydrocarbon group in the side chain is not particularly limited, and propylene glycol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 2,2- Diethyl-1,3-propanediol, 2-ethyl-2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, neopentyl glycol, 3-methyl-1,5 -Pentanediol and the like. These glycol components having a hydrocarbon group in the side chain can be used alone or in combination of two or more. Preferred is propylene glycol, neopentyl glycol, 2-butyl-2-ethyl-1,3-propanediol or 3-methyl-1,5-pentanediol.

<Requirement (5)>
The number average molecular weight of the copolyester resin (A) is in the range of 2500 or more and less than 15000. Preferably it is 3000 or more, More preferably, it is 4000 or more. Moreover, it is preferable that it is 12000 or less, More preferably, it is 10,000 or less. When the number average molecular weight of the copolymerized polyester resin (A) is less than 2500, the number of resin terminal OH groups is too large and a large amount of curing agent is consumed, and the heat resistance of the pressure-sensitive adhesive may deteriorate. In the case of 15000 or more, compatibility with an acrylic resin obtained using an alkyl (meth) acrylate having an alkyl group having 4 to 18 carbon atoms as the main raw material in the acrylic resin (B) deteriorates, and the pressure-sensitive adhesive composition Transparency may decrease.

  The copolymerized polyester resin (A) of the present invention may contain dimer acid or dimer diol as a copolymer component. Since these are high-hydrophobic high molecular weight monomers, the adhesion of the copolymerized polyester resin (A) to the nonpolar substrate can be increased by including dimer acid or dimer diol as a copolymerization component in the composition. .

  The weight average molecular weight of the copolyester resin (A) is preferably 5000 or more, more preferably 6000 or more, and further preferably 8000 or more. If the weight average molecular weight is too small, the number of resin terminal OH groups is too large and a large amount of curing agent is consumed, which may deteriorate the heat resistance of the pressure-sensitive adhesive composition. Moreover, it is preferable that it is 35000 or less, More preferably, it is 30000 or less, More preferably, it is 25000 or less. When too large, compatibility with an acrylic resin (B) may deteriorate, and the transparency of an adhesive composition may fall.

  The glass transition temperature (Tg) of the copolyester resin (A) is preferably −30 ° C. or higher, more preferably −20 ° C. or higher, and still more preferably −from the viewpoint of the balance between tack and adhesive strength. 15 ° C. or higher. Moreover, it is preferable that it is 50 degrees C or less, More preferably, it is 40 degrees C or less, More preferably, it is 30 degrees C or less.

The acid value of the copolyester resin (A) is preferably 5 equivalents / 10 ⁶ g or more, more preferably 10 equivalents / 10 ⁶ g or more. If the acid value is too small, crosslinking with the curing agent (C) may be insufficient, and the adhesive strength may be reduced. Moreover, it is preferable that it is 100 equivalent / 10 < ⁶ > g or less, More preferably, it is 80 equivalent / 10 < ⁶ > g or less. When the acid value is too large, the heat and heat resistance of the resulting pressure-sensitive adhesive composition may be lowered.

  Generally, the reaction for producing a copolyester resin comprises an esterification reaction step and a polycondensation reaction step. The esterification reaction step is a step of producing a low polymer having a desired composition from all monomers and / or a low polymer, and the polycondensation reaction step is a glycol from the low polymer produced in the esterification reaction step. In this step, components are distilled off to obtain a polymer having a desired molecular weight.

  In the production of the copolyester resin (A) of the present invention, a general method for producing a copolyester resin can be used.

  Here, the example of the manufacturing method of copolyester resin is demonstrated.

  In the esterification reaction step, all monomer components and / or their low polymers are heated and melted for reaction. The esterification temperature is preferably 180 to 250 ° C, more preferably 220 to 250 ° C, and the reaction time is preferably 2.5 to 10 hours, more preferably 2.5 to 6 hours. The reaction time is the time from the desired reaction temperature to the subsequent polycondensation reaction.

  In the polycondensation reaction step, the glycol component is distilled off from the esterified product obtained in the esterification reaction step at a temperature of 220 to 280 ° C. under reduced pressure, and the polycondensation reaction proceeds until a desired molecular weight is reached. The reaction temperature for polycondensation is preferably 220 to 270 ° C, more preferably 220 to 250 ° C. The degree of vacuum is preferably 0.1 Torr or less. A low degree of vacuum is not preferable because the polycondensation time tends to be long. It is preferable to gradually reduce the pressure over a period of 15 to 60 minutes as the time for reducing the pressure from atmospheric pressure to 0.1 Torr or less.

  In the esterification reaction and polycondensation reaction, if necessary, organic titanate compounds such as tetrabutyl titanate, alkali metals such as zinc acetate and magnesium acetate, acetates of alkaline earth metals, antimony trioxide, hydroxy Polymerization is performed using an organic tin compound such as butyltin oxide or tin octylate. The amount of the catalyst used at that time is preferably 1.0% by mass or less based on the mass of the resin to be produced.

  In general, when a desired acid value or hydroxyl value is imparted to the copolyester resin, a polybasic acid component or a polyvalent glycol component is further added following the polycondensation reaction, and the reaction is conducted under an inert atmosphere. Depolymerization can be performed.

  In order to impart an acid value to the copolymerized polyester resin (A), for example, after polymerizing the 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 the polyester oligomer. And then introducing a carboxyl group into the polyester resin by 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.

  In the production of the copolyester resin (A) of the present invention, depolymerization can be carried out in the same manner as in the case of producing a general copolyester resin to give a desired acid value or hydroxyl value.

  Although content of copolyester resin (A) is not specifically limited, It is preferable that it is 1 mass part or more with respect to 100 mass parts of acrylic resins (B), More preferably, it is 5 mass parts or more, More preferably It is 10 parts by mass or more. When the amount is less than 1 part by mass, the effect of the copolyester resin (A) is hardly obtained, and the tackiness may not be improved. Moreover, it is preferable that it is 40 mass parts or less, More preferably, it is 35 mass parts or less, More preferably, it is 30 mass parts or less. When it exceeds 40 parts by mass, the compatibility with the acrylic resin (B) is deteriorated, and when the transparency of the coating film (adhesive layer) is deteriorated or tack as an adhesive is lost, it is good for the base material. Adhesion may not be exhibited.

<Acrylic resin (B)>

  The acrylic resin (B) used in the present invention is preferably synthesized using alkyl (meth) acrylate as a main raw material monomer. The alkyl (meth) acrylate is preferably an alkyl (meth) acrylate having an alkyl group having 4 to 18 carbon atoms, specifically, butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate. , Tert-butyl (meth) acrylate, amyl (meth) acrylate, isoamyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate , 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, octadecyl (meth) acrylate And the like can be given. Of these, butyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate and isooctyl acrylate are more preferable. These may be used alone or in combination of two or more. Here, alkyl (meth) acrylate refers to a general term for alkyl acrylate and alkyl methacrylate.

  In the present invention, the composition of the main raw material monomer means that the monomer composition constituting the acrylic resin (B) exceeds 50% by weight, or the monomer having the largest weight ratio among the constituent monomer compositions. Show.

  Alkyl (meth) acrylate is a monomer for developing adhesive strength, and preferably contains 50 mass% or more of alkyl (meth) acrylate, more preferably 60 mass% or more in 100 mass% of the acrylic resin (B). 70 mass% or more is more preferable. If the amount is too small, the adhesiveness of the pressure-sensitive adhesive composition may decrease, or the compatibility with the copolymerized polyester (A) may decrease, which is not preferable. Further, the alkyl (meth) acrylate may be 100% by mass, but is preferably 99.5% by mass or less, and more preferably 99% by mass or less.

  As a raw material monomer for the acrylic resin (B), in addition to the alkyl (meth) acrylate, a monomer containing a functional group (hereinafter also referred to as a functional group-containing monomer) may be used. By introducing the reaction point with the curing agent (C) into the acrylic resin (B), the cohesive force of the pressure-sensitive adhesive composition can be increased. Examples of such functional group-containing monomers include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic anhydride, maleic acid, 2-acryloyloxyethyl succinic acid, 2-acryloyloxyethyl phthalic acid, and 2-acryloyloxyethyl. Carboxyl group-containing monomers such as hexahydrophthalic acid, 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, methyl α- (hydroxymethyl) acrylate, (meth) Hydroxyl group-containing monomers such as poly (caprolactone) modified 2-hydroxyethyl acrylate, α- (hydroxymethyl) ethyl acrylate, polyester diol mono (meth) acrylate obtained from phthalic acid and propylene glycol , Glycidyl (meth) acrylate, and methyl glycidyl (meth) acrylate. In addition, epoxy group-containing monomers such as "cyclomer (registered trademark)" series (manufactured by Daicel Chemical Industries), which are alicyclic epoxy group-containing monomers, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylamino Amino group-containing monomers such as propyl (meth) acrylamide, isocyanate group-containing monomers such as 2-methacryloyloxyethyl isocyanate, methacryloyl isocyanate; 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2- Oxazoline group-containing monomers such as vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, β-chloro (or bromo) ethyl vinyl ether Monochloro (or bromo) vinyl acetate, α-chloro (or bromo) methyl acrylate, halogen group-containing monomers such as 3-chloro (or bromo) -2-hydroxypropyl methacrylate, phosphorus such as 2-acryloyloxyethyl acid phosphate Examples include acid group-containing monomers. These may be used alone or in combination of two or more.

  The functional group-containing monomer may be 0% by mass in 100% by mass of the acrylic resin (B), but is preferably 0.01% by mass or more, more preferably 0.2% by mass or more, and still more preferably. It is 0.5 mass% or more. If the amount is too small, the reaction point with the curing agent (C) may be insufficient and the cohesive force may be reduced. Moreover, it is preferable that it is 10 mass% or less, More preferably, it is 5 mass% or less, More preferably, it is 4 mass% or less, Most preferably, it is 3 mass% or less. When the amount is too large, the reaction point with the curing agent (C) is excessive, so that the crosslink density is increased, and the cohesive force is too high, which may reduce the adhesive strength. Furthermore, it may be gelled when the acrylic resin (B) is polymerized.

  As a raw material monomer for the acrylic resin (B), an aromatic group is added in addition to the alkyl (meth) acrylate and the functional group-containing monomer for the purpose of improving the mechanical properties of the pressure-sensitive adhesive layer and improving the adhesion to the substrate. You may use the monomer to contain. By introducing a monomer containing an aromatic group into the acrylic resin (B), the cohesive force of the pressure-sensitive adhesive composition can be increased. Examples of such aromatic group-containing monomers include phenoxyethyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, and 2- (meta ) Acrylroyoxyethyl-phthalic acid, 2- (meth) acryloyloxyethyl-2-hydroxyethyl-phthalic acid, neopentylglycol- (meth) acrylic acid-benzoic acid ester, ethylene oxide (EO) addition of bisphenol A Product di (meth) acrylate, propylene oxide (PO) adduct di (meth) acrylate of bisphenol A, and the like. These may be used alone or in combination of two or more.

  The monomer containing an aromatic group may be 0% by mass in 100% by mass of the acrylic resin (B), but is preferably 0.5% by mass or more, more preferably 1% by mass or more, and still more preferably. Is 5% by mass or more. Moreover, it is preferable that it is 50 mass% or less, More preferably, it is 45 mass% or less, More preferably, it is 40 mass% or less.

  As a raw material monomer for the acrylic resin (B), an alkoxy (meth) alkyl acrylate may be used for the purpose of improving the adhesiveness to the base material of the pressure-sensitive adhesive layer and the compatibility with the copolymerized polyester resin (A). Absent. By introducing these monomers into the acrylic resin (B), the adhesiveness of the pressure-sensitive adhesive composition to the polar substrate can be improved. Examples of such alkoxyalkyl (meth) acrylates include ethoxy-diethylene glycol (meth) acrylate, methoxy-triethylene glycol (meth) acrylate, methoxy-polyethylene glycol (meth) acrylate, and methoxydipropylene glycol (meth) acrylate. , Methoxymethyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, n-butoxyethyl (meth) acrylate, ethoxypropyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxydiethylene glycol (meth) Acrylate, phenoxypolyethylene glycol (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, etc. Preferably, 2-methoxyethyl (meth) acrylate or 2-ethoxyethyl (meth) acrylate is used. These may be used alone or in combination of two or more.

  The alkoxyalkyl (meth) acrylate may be 0% by mass in 100% by mass of the acrylic resin (B), but is preferably 0.5% by mass or more, more preferably 1% by mass or more, and still more preferably. It is 5 mass% or more. Moreover, it is preferable that it is 50 mass% or less, More preferably, it is 45 mass% or less, More preferably, it is 40 mass% or less.

  In addition to the alkyl (meth) acrylate, functional group-containing monomer, aromatic group-containing monomer and alkoxyalkyl (meth) acrylate, other vinyl monomers can also be used for the acrylic resin (B). Specific examples of other monomers include aromatic monomers such as styrene and α-methylstyrene, vinyl esters such as vinyl acetate and vinyl propionate, nitrogen (N group) -containing monomers such as N-vinylpyrrolidone and acryloylmorpholine, Examples include nitrile group-containing monomers such as (meth) acrylonitrile, amide monomers such as (meth) acrylamide and N-methylolacrylamide, but are not particularly limited. These other monomers are preferably 0 to 20% by mass in 100% by mass of the acrylic resin (B). If it exceeds 20% by mass, the glass transition temperature (Tg) of the acrylic resin (B) is increased, and the adhesive strength may be lowered, which is not preferable.

  The acrylic resin (B) is preferably obtained using an alkyl (meth) acrylate having an alkyl group having 4 to 18 carbon atoms as a main raw material. In 100% by mass of the acrylic resin (B), the alkyl (meth) acrylate having an alkyl group having 4 to 18 carbon atoms is preferably 90% by mass or more, more preferably 93% by mass, and still more preferably 95% by mass. %.

  The acrylic resin (B) of the present invention preferably has adhesiveness at room temperature (about 23 ° C.). The glass transition temperature (Tg) of the acrylic resin (B) is preferably in the range of −80 to 0 ° C., more preferably in the range of −70 to −20 ° C., from the viewpoint of the balance between tack and adhesive strength. More preferably, it is in the range of -70 to -40 ° C. Tg can be determined by DSC (Differential Scanning Calorimetry) or TMA (Thermomechanical Measurement Device).

  The number average molecular weight of the acrylic resin (B) is preferably in the range of 100,000 to 300,000, more preferably in the range of 120,000 to 200,000, from the viewpoint of the balance between tackiness and adhesiveness.

The acid value of the acrylic resin (B) is not particularly limited, but is 50 equivalents / 10 ⁶ g or more when a curing agent (C) that reacts with a carboxylic acid is used or when high adhesion to a polar substrate is required. Is more preferably 100 equivalents / 10 ⁶ g or more, and still more preferably 200 equivalents / 10 ⁶ g or more. If the acid value is too small, crosslinking with the curing agent (C) may be insufficient, and the adhesive strength may be reduced. Moreover, it is preferable that it is 500 equivalent / 10 < ⁶ > g or less, More preferably, it is 400 equivalent / 10 < ⁶ > g or less, More preferably, it is 300 equivalent / 10 < ⁶ > g or less. When the acid value is too large, the heat and heat resistance of the resulting pressure-sensitive adhesive composition may be lowered.

  The acrylic resin (B) can be polymerized using an existing polymerization method such as a solution polymerization method or a bulk polymerization method. The polymerization method is not particularly limited, but a solution polymerization method is preferable because it is easy to remove heat of reaction during the polymerization. The solvent to be used is not particularly limited, but aromatic hydrocarbons such as toluene and xylene, aliphatic esters such as ethyl acetate and butyl acetate, alicyclic hydrocarbons such as cyclohexane, and aliphatic hydrocarbons such as hexane and pentane. And the like. These solvents may be used alone or in combination of two or more.

  Examples of the polymerization initiator include methyl ethyl ketone peroxide, benzoyl peroxide, dicumyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, t-butyl peroxy octoate, t-butyl peroxy benzoate, lauroyl peroxide, etc. Known radical polymerization initiators such as organic peroxides and azo compounds such as azobisisobutyronitrile can be used. Further, for the purpose of reducing the amount of residual monomer, a post-addition initiator (booster) may be added in the latter stage of polymerization.

  The total amount of the polymerization initiator is preferably 0.01 to 3% by mass with respect to the mass of the raw material monomer. When it exceeds 3 mass%, a high molecular weight acrylic resin (B) having excellent adhesive properties may not be obtained. In terms of adhesive properties, the acrylic resin (B) has a weight average molecular weight (Mw) of preferably 200,000 or more, more preferably 300,000 or more. Although an upper limit is not specifically limited, Since it is difficult to synthesize a polymer exceeding 2 million in solution polymerization, it is preferably 2 million or less, and more preferably 1.5 million or less. Moreover, you may use well-known chain transfer agents, such as a mercapto compound, as needed.

  The polymerization conditions such as polymerization temperature and polymerization time depend on, for example, the composition of the raw material monomer mixture, the type of the polymerization solvent, the polymerization initiator, the required characteristics of the resulting acrylic resin (B), the use of the pressure-sensitive adhesive composition, etc. May be set as appropriate, and is not particularly limited. The polymerization reaction is desirably performed in an atmosphere of an inert gas such as nitrogen gas.

<Curing agent (C)>

  The pressure-sensitive adhesive composition of the present invention contains a curing agent (C) in order to crosslink the copolyester resin (A) and the acrylic resin (B). The curing agent (C) is preferably a compound having a functional group reactive to both the functional group introduced into the copolyester resin (A) and the functional group introduced into the acrylic resin (B). . As the curing agent (C), a compound having two or more functional groups in one molecule can be used. Examples of such functional groups include isocyanate groups, epoxy groups, amino groups, methylol groups, alkoxymethyl groups, imino groups, metal chelate groups, aziridinyl groups, and the like. Specific examples of the compound include a polyfunctional isocyanate compound, a polyfunctional epoxy compound, a polyfunctional melamine compound, a metal crosslinking agent, and a polyfunctional aziridine compound.

  A polyfunctional isocyanate compound is a compound having two or more isocyanate groups per molecule. Polyfunctional isocyanate compounds include tolylene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate, orthoxylylene diisocyanate, metaxylylene diisocyanate, paraxylylene diisocyanate, 1,5-naphthalene diisocyanate. 1,4-naphthalene diisocyanate, 1,8-naphthalene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate and the like. Alternatively, a bullet polyisocyanate compound such as “Sumijoule (registered trademark) N” (manufactured by Sumika Bayer Urethane Co., Ltd.), “Desmodur (registered trademark) IL”, “Desmodur HL” (both manufactured by Bayer AG) ), Polyisocyanate compounds having an isocyanurate ring known as “Coronate (registered trademark) EH” (manufactured by Nippon Polyurethane Industry Co., Ltd.), or adduct polyisocyanate compounds such as “Sumijoule L” (manufactured by Sumika Bayer Urethane Co., Ltd.) And adduct polyisocyanate compounds such as “Coronate L” and “Coronate L-45E” (all manufactured by Nippon Polyurethane Industry Co., Ltd.). These may be used alone or in combination of two or more. It is also possible to use blocked isocyanates which are inactivated by reacting with a masking agent having active hydrogen with respect to the isocyanate groups of these compounds.

  As the polyfunctional epoxy compound, a compound having two or more epoxy groups per molecule can be used. Specific examples include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, bisphenol A / epichlorohydrin type epoxy resin, N, N, N ′, N′-tetraglycidyl-m- Examples include xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N-diglycidylaniline, N, N-diglycidyltoluidine, and the like. These may be used alone or in combination of two or more.

  As the polyfunctional melamine compound, a compound having two or more methylol groups, alkoxymethyl groups or imino groups per molecule in total can be used. Specific examples include hexamethoxymethyl melamine, hexaethoxymethyl melamine, hexapropoxymethyl melamine, hexabutoxymethyl melamine, hexapentyloxymethyl melamine and the like. These may be used alone or in combination of two or more.

  Specific examples of the metal cross-linking agent include aluminum, zinc, cadmium, nickel, cobalt, copper, calcium, barium, titanium, manganese, iron, lead, zirconium, chromium, tin and the like, acetylacetone, methyl acetoacetate Examples thereof include metal chelate compounds coordinated with ethyl acetoacetate, ethyl lactate, methyl salicylate and the like, but are not particularly limited.

  A polyfunctional aziridine compound is a compound having two or more aziridine groups per molecule. Examples of the polyfunctional aziridine compound include N, N′-hexamethylene-1,6-bis (1-aziridinecarboxamide), trimethylolpropane-tri-β-aziridinylpropionate, bisisophthaloyl-1- (2-methylaziridine), tri-1-aziridinyl phosphine oxide, N, N′-diphenylethane-4,4′-bis (1-aziridinecarboxamide) and the like can be used.

  Although content of a hardening | curing agent (C) is not specifically limited, It is preferable that it is 0.05 mass part or more with respect to 100 mass parts of acrylic resins (B), More preferably, it is 0.1 mass part or more, It is more preferably 0.5 parts by mass or more, particularly preferably 1 part by mass or more. If the amount is less than 0.05 parts by mass, the curing is insufficient, the crosslinking density is low, the cohesive force is insufficient, and the heat resistance may be insufficient. Moreover, it is preferable that it is 15 mass parts or less, More preferably, it is 10 mass parts or less, More preferably, it is 8 mass parts or less, Most preferably, it is 5 mass parts or less. When it exceeds 15 parts by mass, the crosslinking density becomes too high, the tackiness of the pressure-sensitive adhesive composition may be deteriorated, and the adhesive strength may be lowered.

<Adhesive composition>
The pressure-sensitive adhesive composition of the present invention is a composition containing the copolymer polyester resin (A), the acrylic resin (B), and the curing agent (C). In 100% by mass of the solid content of the pressure-sensitive adhesive composition, the total of the copolymerized polyester resin (A), the acrylic resin (B) and the curing agent (C) is preferably 80% by mass or more, more preferably 85% by mass. Or more, more preferably 90% by mass or more, and particularly preferably 95% by mass or more. If the amount is too small, the effects of the present invention, such as tackiness, heat resistance, holding power and transparency, may not be achieved. The pressure-sensitive adhesive composition of the present invention includes known crosslinking agents, wetting agents, viscosity modifiers, thickeners, antifoaming agents, modifiers, pigments, colorants, fillers, anti-aging agents, ultraviolet absorbers, You may add additives, such as a ultraviolet stabilizer, in the range which does not inhibit the objective of this invention.

  In order to express a good function as a pressure-sensitive adhesive composition by crosslinking of the copolymerized polyester resin (A), the acrylic resin (B) and the curing agent (C), a solvent-insoluble component (gel fraction) after the crosslinking treatment However, it is preferable that it is 40 weight% or more. More preferably, it is 50 weight% or more. If the solvent-insoluble component is less than 40% by weight, the cohesive force of the pressure-sensitive adhesive composition 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 exceeds 85% by weight, the flexibility of the crosslinked body of the copolymerized polyester resin (A) and the acrylic resin (B) is impaired, and the tackiness tends to be lowered.

  In addition to the copolymer polyester resin (A), the acrylic resin (B) and the curing agent (C), if necessary, the pressure-sensitive adhesive composition prepared by mixing an antioxidant, the above-mentioned various additives, a solvent, etc. For example, it can be suitably used for the production of various adhesive products such as an adhesive sheet, an adhesive label, an adhesive tape, a double-sided tape. Such a pressure-sensitive adhesive product is produced without a base material or by forming a layer of a pressure-sensitive adhesive composition on a base material and causing a crosslinking reaction.

  As a base material, conventionally well-known papers such as high-quality paper, kraft paper, crepe paper, glassine paper, or plastics such as polyethylene, polypropylene, polyester, polystyrene, polyethylene terephthalate, polyvinyl chloride, cellophane, or aluminum in these plastics A metal vapor deposition film such as (Al) or a fiber product such as a woven fabric or a non-woven fabric can be used. Examples of the shape of the substrate include, but are not particularly limited to, a film shape, a sheet shape, a tape shape, a plate shape, and a foam. An adhesive sheet, an adhesive tape, an adhesive label, etc. can be obtained by apply | coating an adhesive composition to the single side | surface of a base material by a well-known method. In addition, by applying the adhesive composition to release paper, etc., in which a release agent is applied to a sheet-like material such as paper, synthetic paper, plastic film, etc., a substrate-less (single layer structure) adhesive layer is formed. It can also be used as a baseless double-sided tape. Moreover, it is good also as a double-sided tape by apply | coating the same kind or different kind of adhesive composition on both surfaces of the said base material.

  The method for applying the pressure-sensitive adhesive composition to the substrate may be a known method such as a roll coating method, a spray coating method, or a dipping method, but is not particularly limited. Any of a method of directly applying the pressure-sensitive adhesive composition to the substrate, a method of applying the pressure-sensitive adhesive composition to a release paper, and then transferring the coated material onto the substrate can be employed.

  After apply | coating an adhesive composition, an adhesive layer is formed on a base material by making it dry. The drying temperature is not particularly limited. In addition, depending on a use, you may apply | coat an adhesive composition directly to a to-be-adhered body. The pressure-sensitive adhesive product on which the pressure-sensitive adhesive layer is formed is preferably cured. The curing conditions may be determined by appropriately determining temperature, humidity, and time.

  For example, release paper may be attached to the surface of the pressure-sensitive adhesive layer formed on the substrate. The pressure-sensitive adhesive layer surface can be suitably protected and preserved. The release paper is peeled off from the surface of the pressure-sensitive adhesive layer when the pressure-sensitive adhesive product is used. If a pressure-sensitive adhesive layer is formed on one side of a substrate such as a sheet or tape, a known release agent is applied to the back of the substrate to form a release agent layer. By rolling the pressure-sensitive adhesive sheet (tape) in a roll shape with the pressure-sensitive adhesive layer inside, the pressure-sensitive adhesive layer comes into contact with the release agent layer on the back surface of the substrate, so that the surface of the pressure-sensitive adhesive layer is protected. Saved.

  The thickness of an adhesive layer is 1-500 micrometers normally, Preferably it is 5-300 micrometers, More preferably, it is 10-200 micrometers. If it is too small, the adhesive strength may be insufficient.

  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 copolyester resin (A) The composition and composition ratio of the copolyester resin (A) were determined by ¹ H-NMR measurement (proton nuclear magnetic resonance spectroscopy) at 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) Number average molecular weight (Mn) / weight average molecular weight (Mw)
A sample (copolyester resin (A) or acrylic resin (B)) is dissolved in tetrahydrofuran so that the sample concentration is 0.5% by mass, and filtered through a polytetrafluoroethylene membrane filter having a pore size of 0.5 μm. This was used 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, the average molecular weight and the weight average molecular weight of each sample were measured at a column temperature of 35 ° C. and a flow rate of 1 ml / min. Analysis was by gel 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.

(3) Glass transition temperature (Tg)
It measured with the differential scanning calorimeter (SII company, DSC-200). A sample (copolymerized polyester resin (A) or acrylic resin (B)) 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.

(4) Acid value 0.2 g of a sample (copolyester resin (A) or acrylic resin (B)) 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. Against copolymerized polyester (A) or the acrylic resin (B), obtains a potassium hydroxide equivalent, was determined in terms of equivalents / 10 6 ^g units.

(5) Preparation method of adhesive tape Copolyester resin (A), acrylic resin (B), and hardening | curing agent (C) were dissolved in ethyl acetate, and the adhesive composition with a solid content concentration of 30% was obtained. After applying the adhesive composition 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 25 μm, volatilizing the solvent, silicone coating The film was pressed 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 layer, and the silicone-coated film was peeled off to obtain a polyester film / pressure-sensitive adhesive layer laminate. Hereinafter, this laminate is referred to as an adhesive sheet A.

(6) Gel fraction The pressure-sensitive adhesive sheet A was cut into a strip of 2.5 cm in length and 10 cm in width and weighed (this weight is designated as A), and immersed in an ethyl acetate solution 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

(7) Adhesive strength At room temperature (23 ° C.), the adhesive sheet A was cut into a width of 25 mm and a length of 200 mm, the adhesive layer surface was attached to the following substrate, and a speed of 20 mm / sec with a 2 kg rubber roller from above. The pressure-sensitive adhesive sheet A was pressure-bonded to the substrate. After 24 hours, the 180 ° peel adhesive strength was measured under the peel speed of 300 mm / min to obtain the adhesive strength. Further, the state of the peeled substrate was confirmed as interfacial peeling or cohesive peeling. As a comprehensive evaluation of the adhesive strength, the adhesive strength to the base material A is 12.0 N / 2.5 mm or more, the adhesive strength to the base material B is 7.0 N / 2.5 mm or more, and any peeling state is an interface. The level of peeling was marked with ◯, and the others were marked with x.
The following materials were used.
Base material A: Stainless steel base material (SUS304 steel plate thickness 1.5 mm)
Base material B: PET film (Toyobo Co., Ltd., P2161 thickness 50 μm)

(8) Holding power and heat resistance At room temperature (23 ° C.), the pressure-sensitive adhesive sheet is cut into a width of 25 mm and a length of 100 mm, and a width of 25 mm and a length of 25 mm of the pressure-sensitive adhesive layer surface are attached to a stainless steel plate (SUS304). The adhesive sheet and the stainless steel plate were pressure-bonded by reciprocating twice at a speed of 20 mm / second with a 2 kg rubber roller from above. After standing at 23 ° C. for 30 minutes, a load of 1.0 kg was applied under the conditions of room temperature (23 ° C.) 50 RH%, 80 ° C., 150 ° C., and after 24 hours, the distance (mm) that the adhesive sheet was displaced from the stainless steel plate was measured. did. The case where the deviation was less than 0.5 mm was rated as ◎, the case where it was 0.5 mm or more and less than 1.0 mm, ◯, the case where it was 1.0 mm or more, Δ, and the case where the adhesive layer was completely peeled off and dropped.

(9) Transparency Copolyester resin (A), acrylic resin (B), and curing agent (C) were dissolved in ethyl acetate to obtain a pressure-sensitive adhesive composition having a solid content concentration of 30%. After the adhesive composition is applied to the silicone coat film with an applicator so that the dry film thickness (film thickness after drying) is 25 μm and the solvent is volatilized, another silicone coat film is further removed using a dry laminator. Crimped. 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 layer, and one of the silicone-coated films was peeled off to obtain a silicone-coated film / pressure-sensitive adhesive layer laminate. Hereinafter, this laminate is referred to as an adhesive sheet B.
The adhesive sheet B was cut into a width of 25 mm and a length of 25 mm, the adhesive layer surface of the adhesive sheet B was attached to a glass plate having a thickness of 1.1 mm, and the silicone-coated film was peeled off to obtain a glass plate / adhesive laminate. The haze of this laminate was measured using NDH7000 manufactured by Nippon Denshoku Industries Co., Ltd. A haze value of 1.0% or less was judged as ◯.

Synthesis of Copolyester Resin (A-1) In a reaction vessel equipped with a stirrer, thermometer, heater, cooling device, and distillation cooler, 84 parts by mass of 1,4-cyclohexanedicarboxylic acid, hexahydrophthalic anhydride 76 parts by mass of acid, 4 parts by mass of trimellitic anhydride, 91 parts by mass of propylene glycol, 128 parts by mass of 2-butyl-2-ethyl-1,3-propanediol and 0.10 parts by mass of tetrabutyl titanate were charged at 230 ° C. The esterification reaction was carried out over 4 hours while raising the temperature. 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 250 ° C., and the pressure was further reduced to 1 torr or less under vacuum to carry out a polycondensation reaction at 250 ° C. for 20 minutes. Thereafter, the polycondensation reaction was terminated by flowing nitrogen into the system and breaking the vacuum. After completion of the reaction, the copolyester resin was taken out and cooled to obtain a copolyester resin (A-1). As a result of NMR analysis, the obtained copolyester resin (A-1) has a carboxylic acid component in a molar ratio of 1,4-cyclohexanedicarboxylic acid / hexahydrophthalic anhydride / trimellitic anhydride = 49/49/2. The glycol component was propylene glycol / 2-butyl-2-ethyl-1,3-propanediol = 50/50 in molar ratio. The measurement results of the resin physical properties are shown in Table 1.

Synthesis of Copolyester Resin (A-2) to (A-10) Similar to Synthesis Example of Copolyester Resin (A-1), Copolyester Resin (A-2) whose composition is shown in Table 1 -(A-10) was synthesized. The measurement results of the resin physical properties are shown in Table 1.

Synthesis of acrylic resin (B-1) In a reaction can equipped with a stirrer, thermometer, heater, and cooling device, 96 parts by mass of butyl acrylate, 2 parts by mass of acrylic acid, 2 parts by mass of 2-hydroxyethyl acrylate, azo Charge 0.3 parts by weight of bisisobutyronitrile to 0.3% by weight with respect to the total amount of acrylic monomers and 150 parts by weight of ethyl acetate, flow nitrogen into the system, raise the temperature to 70 ° C. and take 4 hours. The radical polymerization reaction was performed. The measurement results are shown in Table 2 together with the charged composition and the resin physical properties in the weight ratio of the obtained acrylic resin.

Synthesis of acrylic resin (B-2) An acrylic resin (B-2) having a composition shown in Table 2 was synthesized in the same manner as in the synthesis example of the acrylic resin (B-1). Table 2 shows the measurement results of the resin physical properties.

In Examples 1 to 10 and Comparative Examples 1 to 7, the copolymer polyester resin (A) and the acrylic resin (B) were dissolved in ethyl acetate so that the solid content concentration was 30% by mass. A curing agent (C) was blended with the dissolved material according to the amount shown in Table 3 to obtain an adhesive composition. The amount of resin in Table 3 indicates a value as a resin solid content. The following isocyanate curing agents were used.
Hardener C: Coronate L-45E manufactured by Tosoh Corporation

  In Examples 1 to 10, all of the obtained pressure-sensitive adhesive compositions exhibited good adhesive force to the substrate, and the peeled state was also interfacial peeling. Moreover, the holding power was good even under a high temperature environment, the transparency was high, and the performance as an adhesive was excellent.

  In Comparative Example 1, the adhesiveness to all the substrates was good, but the transparency was poor. Since there are many aromatic dicarboxylic acid components of copolymer polyester resin (A), compatibility with an acrylic resin (B) deteriorated and it is thought that transparency deteriorated. In addition, the coercive polyester resin (A) has a slightly inferior result in holding power at high temperatures because it does not have a branched structure.

  In Comparative Example 2, the transparency was good and the interfacial delamination resulted in poor adhesion to all substrates. In addition, the retention at high temperature was inferior. Since the content of the alicyclic dicarboxylic acid component of the copolymer polyester resin (A) is small, the mechanical strength of the copolymer polyester resin (A) is lowered, and it is considered that the adhesion and heat resistance are insufficient.

  In Comparative Example 3, although the adhesive force to all the substrates was good and the holding power at high temperature was also good, the result was inferior in transparency. It is considered that the compatibility with the acrylic resin (B) deteriorated because the content of glycol having a hydrocarbon group in the side chain of the copolymerized polyester resin (A) was small.

  In Comparative Example 4, although the adhesive force to all the substrates was good and the holding power at high temperature was good, the results were inferior in transparency. It is considered that the compatibility with the acrylic resin (B) deteriorated because the molecular weight of the copolymerized polyester resin (A) was too high.

  In Comparative Example 5, although the transparency was good, the peeled state from the base material was cohesive peeling, and the holding power was inferior. Because the molecular weight of the copolyester resin (A) is too low, the number of terminal OH groups of the copolyester resin (A) is increased, and it becomes impossible to sufficiently react with the curing agent, resulting in insufficient curing of the pressure-sensitive adhesive layer. it is conceivable that.

  Since Comparative Example 6 and Comparative Example 7 did not contain the copolyester resin (A), the adhesive strength to all base materials and the holding power at high temperatures were inferior.

  As is clear from Examples 1 to 10 and Comparative Examples 1 to 7, the copolymerized polyester resin of the present invention and the pressure-sensitive adhesive composition containing the same show a good adhesive force to the base material, and retainability even in a high-temperature environment. The film was good, had high transparency, and exhibited excellent performance as an adhesive.

  The polyester resin of the present invention is useful as a resin raw material for pressure-sensitive adhesives, and pressure-sensitive adhesives containing such polyester-based resins have various properties such as adhesive strength, heat resistance, holding power and transparency. It can be suitably used as a pressure-sensitive adhesive for applications.

Claims (5)

Copolyester resin (A) that satisfies the following (1) to (5).
(1) A polyvalent carboxylic acid component and a polyhydric alcohol component are used as a copolymerization component.
(2) When the polyvalent carboxylic acid component of the copolymerized polyester resin (A) is 100 mol%, the content of the aromatic dicarboxylic acid component is 30 mol% or less.
(3) When the polyvalent carboxylic acid component of the copolymerized polyester resin (A) is 100 mol%, the content of the alicyclic dicarboxylic acid component is 40 mol% or more.
(4) When the polyhydric alcohol component of the copolymerized polyester resin (A) is 100 mol%, the content of the glycol component having a hydrocarbon group in the side chain is 30 mol% or more.
(5) The number average molecular weight of the copolyester resin (A) is in the range of 2500 or more and less than 15000.   The copolymer polyester resin (A) according to claim 1, wherein the alicyclic dicarboxylic acid component is 1,4-cyclohexanedicarboxylic acid, hexahydrophthalic anhydride or 1,2-cyclohexanedicarboxylic acid.   The glycol component having a hydrocarbon group in the side chain is 2,2-dimethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, propylene glycol or 3-methylpentanediol. The copolyester resin (A) according to any one of claims 1 and 2.   The copolyester resin (A) according to any one of claims 1 to 3, comprising a branched structure.   The adhesive composition containing the copolyester resin (A) in any one of Claims 1-4, an acrylic resin (B), and a hardening | curing agent (C).