Release adhesive composition, release adhesive, and release adhesive sheet

Abstract

To provide a peelable adhesive that is used for bonding an adhesive sheet to an adherend so that the adhesive sheet once bonded is to be peeled off the adherend, the adhesive capable of preventing the adhesive sheet from breaking when it is peeled off.MEANS FOR SOLVING THE PROBLEM: A peelable adhesive composition contains polyester resin (A), the density of unsaturated groups being 0.01-1.5 mmol / g.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a release adhesive composition, and more particularly to a release adhesive composition used in semiconductor processing sheets, and more particularly to a release adhesive composition used in a backgrind sheet that is attached to the surface of a semiconductor wafer during back grinding. [Background technology]

[0002] As information terminal devices become thinner, smaller, and more multifunctional, the semiconductor devices installed in them are also required to be thinner and denser. To make the devices thinner, there is a demand for thinner semiconductor wafers on which semiconductors are integrated, and for this reason, the back surface of the semiconductor wafer is sometimes ground down to make it thinner. Furthermore, the wafer surface often has bumps (electrodes) made of solder or the like, resulting in uneven surfaces. When such a bumped semiconductor wafer is back-ground, a semiconductor processing sheet is attached to the wafer surface to protect the surface with the bumps. Conventionally, adhesive sheets comprising a base material and an adhesive layer provided on one side of the base material are commonly used as semiconductor processing sheets.

[0003] The semiconductor processing sheets described above require the ability to embed bumps and follow steps in order to properly protect uneven areas such as bumps on the wafer surface. Furthermore, if adhesive residue from the semiconductor processing sheet remains on the uneven areas of the semiconductor wafer, this adhesive residue may cause malfunctions in the semiconductor device. For this reason, for example, Patent Document 1 discloses that, in order to improve step-following ability and suppress adhesive residue on uneven areas, an intermediate layer and an adhesive layer are provided on the substrate of the semiconductor processing sheet, and the intermediate layer and adhesive layer are formed from a specific acrylic polymer. Furthermore, Patent Document 2 proposes an adhesive that uses a polyester resin instead of the acrylic resin commonly used as the base resin for adhesives, and further incorporates an unsaturated group-containing compound into the resin composition, which is then crosslinked by irradiation with ultraviolet light. This adhesive hardens when crosslinked by ultraviolet irradiation, reducing its adhesive strength and improving its peelability. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2015 / 111310 [Patent Document 2] Japanese Patent Publication No. 2009-221249 [Overview of the project] [Problems that the invention aims to solve]

[0005] In recent years, semiconductor devices have become increasingly high-resolution, and as a result, minute grooves and other features are formed on the uneven surfaces. This has led to a problem where adhesive sheets break when peeled off, leaving behind adhesive residue.

[0006] The adhesive sheet described in Patent Document 1 has an intermediate layer between the substrate and the adhesive layer to improve embedding properties, but there is a risk of delamination occurring between this intermediate layer and the adhesive layer when peeling off the adhesive layer. Furthermore, the inclusion of an intermediate layer complicates the manufacturing of the adhesive sheet, so there is a need for an adhesive layer that can perform the roles of both the intermediate layer and the adhesive layer in a single layer.

[0007] Furthermore, while the adhesive sheets described in Patent Documents 1 and 2 can reduce adhesive residue while improving embedding properties for bumps, it was difficult to adequately prevent the adhesive sheet from tearing. In other words, while the adhesive sheets described in Patent Documents 1 and 2 can reduce adhesive residue for flat substrates, when embedding bumps or other irregularities, a portion of the adhesive layer tends to get physically caught on the uneven surface, tear, and remain as adhesive residue. In particular, if the elongation of the adhesive sheet is low, it does not stretch and easily tears, which is a problem as it tends to result in adhesive residue.

[0008] Therefore, against this background, the present invention aims to provide an adhesive used in applications where an adhesive sheet and an adherend are to be peeled off after being bonded together, a release adhesive that can prevent the adhesive sheet from tearing when it is peeled off, a release adhesive composition that can form such an adhesive, and a release adhesive sheet. [Means for solving the problem]

[0009] However, in view of these circumstances, the inventors conducted extensive research and, as a result, discovered that in a release adhesive composition containing a polyester resin, an adhesive using a release adhesive composition having a specific unsaturated group concentration exhibits moderate adhesive strength that allows for re-peelability, and also increases elongation, thus completing the present invention.

[0010] In other words, the present invention provides the following [1] to

[10] . [1] A release adhesive composition comprising a polyester resin (A), wherein the unsaturated group concentration is 0.01 to 1.5 mmol / g. [2] The release adhesive composition according to [1], wherein the unsaturated group concentration is 0.01 to 1.0 mmol / g. [3] The release adhesive composition according to [1] or [2], wherein the content of the polyester resin (A) is 50% by weight or more of the entire release adhesive composition. [4] The release adhesive composition according to any one of [1] to [3], wherein the polyester resin (A) is an unsaturated group-containing polyester resin (A1). [5] A release adhesive composition according to any one of [1] to [4] further comprising a crosslinking agent (B). [6] The peelable adhesive composition according to any one of [1] to [5], wherein the crosslinking agent (B) has functional groups and unsaturated groups that react with the polyester resin (A). [7] A release adhesive composition according to any one of [1] to [6] further comprising a polymerization initiator (C). [8] A release adhesive obtained by using the release adhesive composition according to any one of [1] to [7]. [9] A release adhesive sheet having a substrate and an adhesive layer containing the release adhesive according to [8].

[10] The release adhesive sheet according to [9], wherein the adhesive strength (β) of the release adhesive sheet is 2 N / 25 mm or less. Adhesive strength (β): The release adhesive sheet is attached to the SUS-BA plate of the adherend, left standing at 23°C and 50% RH for 30 minutes or more, and then irradiated with ultraviolet rays (500 mJ / cm 2 ), and the 180-degree peel strength (N / 25 mm) measured according to JIS Z0237

[0011] So far, many adhesive sheets using a release adhesive containing an acrylic resin have been designed. The release adhesive using the above acrylic resin utilizes the side-chain functional groups of the acrylic resin to incorporate unsaturated groups or to serve as reaction points with a crosslinking agent. By creating an adhesive sheet from this release adhesive using the acrylic resin and irradiating it with an energy ray such as ultraviolet rays, the functional groups on the side chain of the acrylic resin, the crosslinking agent, and the unsaturated groups on the side chain of the acrylic resin are chemically reacted and integrated to obtain a release adhesive sheet for semiconductor processing with very little residue and re-peelability. The above acrylic resin can easily have functional groups at a high concentration in the side chain by controlling the copolymerization monomer, so the reaction with unsaturated groups and crosslinking agents was very easy.

[0012] On the one hand, when using a polyester resin as a release adhesive, usually, since the polyester resin has functional groups only at the molecular terminals, it is difficult to introduce a high concentration of unsaturated groups by utilizing these functional groups (by reacting with a compound having a functional group that reacts with the functional group and an unsaturated group). In the case of a polyester resin, when increasing the content of unsaturated groups as in the above acrylic resin, it is necessary to increase the end groups, which results in a decrease in molecular weight, and there is a concern that the adhesive residue will increase. That is, when considering incorporating unsaturated groups into a polyester resin or using the functional groups of a polyester resin as reaction points with a crosslinking agent, the number of functional groups possessed by the polyester resin tends to be insufficient, so it has been considered unsuitable for such usage.

[0013] Therefore, in a release adhesive sheet using a polyester resin, it has been considered difficult to design it other than by adding an unsaturated group-containing compound as in the above Patent Document 2. However, this time, by controlling the unsaturated group concentration, a re-releasable adhesive with less adhesive residue for semiconductor processing, in which the network of the adhesive layer is integrated using a polyester resin, was designed. Moreover, surprisingly, compared with an acrylic resin having a functional group that can form a crosslinked structure in the side chain, by using a polyester resin having a functional group at the molecular terminal, it was possible to design an adhesive that is very easy to stretch. Although the details are unclear, it is considered that this is because the molecular weight between crosslinking points increased due to the use of a polyester resin.

Advantages of the Invention

[0014] The release adhesive composition of the present invention can have a re-releasable adhesive force and can further increase the elongation when used as a release adhesive. Therefore, the above release adhesive has a low adhesive force after energy application and can be easily peeled off. In addition, since the elongation is high, even when the adhesive gets physically caught on the uneven portions, the adhesive does not break and it is difficult for the adhesive residue to remain. Furthermore, due to the high elongation, by performing a heat and pressure treatment as necessary, it becomes easy to follow the steps during pasting. In other words, the release adhesive composition of the present invention can be an adhesive with low adhesive strength and high elongation after energy application, and will have excellent release properties, reduced adhesive residue, and ability to follow uneven surfaces.

[0015] The release adhesive composition of the present invention is an adhesive composition used in release adhesive sheets, and can be used in any layer of the adhesive sheet, such as the adhesive layer or the intermediate layer, but is preferably used in the adhesive layer. The adhesive layer is the part that comes into direct contact with the adherend and is the layer that peels off when the release adhesive sheet is peeled off from the adherend, while the intermediate layer is the layer inside the adhesive layer and does not come into direct contact with the adherend. [Modes for carrying out the invention]

[0016] The configuration of the present invention will be described in detail below, but these are merely examples of preferred embodiments. Furthermore, in this invention, "(meth)acrylic" means acrylic or methacrylic, "(meth)acryloyl" means acryloyl or methacryloyl, and "(meth)acrylate" means acrylate or methacrylate. Furthermore, in this invention, "x and / or y (where x and y are any configuration or component)" means three possible combinations: x only, y only, and x and y.

[0017] <Releasable adhesive composition> First, we will describe a peelable adhesive composition (hereinafter referred to as "this peelable adhesive composition") which is one embodiment of the present invention. This release adhesive composition contains a polyester resin (A), and in addition to the polyester resin (A), it may preferably contain a crosslinking agent (B), a polymerization initiator (C), and optionally a hydrolysis inhibitor (D), an active energy ray curable compound (E), etc.

[0018] This release adhesive composition has an unsaturated group concentration of 0.01 to 1.5 mmol / g, preferably 0.03 to 1.2 mmol / g, more preferably 0.1 to 1.0 mmol / g, and even more preferably 0.2 to 0.8 mmol / g. Within this range, the effects of the present invention can be obtained.

[0019] The above unsaturated group concentration (mmol / g) can be calculated using the following formula. However, in the following formula, only the active ingredients contained in the release adhesive composition are used for the calculation, excluding solvents, etc. The unsaturated group concentration (mmol / g) of the release adhesive composition = Amount of unsaturated group-containing compound in the release adhesive composition (mmol) / Total weight of the release adhesive composition (g)

[0020] Furthermore, the above unsaturated group concentration can also be determined by measurement using known methods. For example, the unsaturated group concentration of a release adhesive composition is determined at a resonance frequency of 400 MHz. 1 H-NMR measurement (proton-type nuclear magnetic resonance spectroscopy), 13 It can be determined from the spectrum obtained by 13C-NMR (carbon-type nuclear magnetic resonance spectroscopy). The measurement instrument used is a VARIAN NMR spectrometer 400-MR, and deuterated chloroform can be used as the solvent.

[0021] In this peelable adhesive composition, the unsaturated group is not particularly limited as long as it is a functional group having a carbon-carbon double bond or a carbon-carbon triple bond, but preferably a functional group having a carbon-carbon double bond is preferred, and more preferably an acryloyl group or a methacryloyl group that can be easily used with commonly used ultraviolet irradiators.

[0022] To achieve the desired range for the unsaturated group concentration in the release adhesive composition, methods include (i) introducing unsaturated groups into a polyester resin (A), (ii) introducing unsaturated groups into a crosslinking agent (B), (iii) adding an unsaturated group-containing compound, or combinations thereof. However, methods (i) and (ii) or combinations thereof are preferred in terms of integrating the adhesive layer after curing.

[0023] The glass transition temperature of this release adhesive composition is preferably 30°C or lower, more preferably 20°C or lower, even more preferably 10°C or lower, and especially preferably 0°C or lower, from the viewpoint of balancing adhesive properties and various functionalities. If the glass transition temperature is too high, flexibility is lost, initial tackiness decreases, it becomes difficult to exert sufficient adhesive force with pressure such as finger pressure, and workability tends to decrease. The lower limit of the glass transition temperature is usually -90°C, preferably -60°C, and more preferably -40°C. Here, the glass transition temperature (Tg) of the above-mentioned peelable adhesive composition is measured using a differential scanning calorimeter.

[0024] The release adhesive composition preferably contains substantially no acidic groups. Specifically, it is preferable that the acid value is 10 mg KOH / g or less, more preferably 5 mg KOH / g or less, particularly preferably 3 mg KOH / g or less, even more preferably 1 mg KOH / g or less, and especially preferably 0.5 mg KOH / g or less. The lower limit of the acid value is usually 0 mg KOH / g. The acid value of the above release adhesive composition is determined by neutralization titration in accordance with JIS K0070. In this invention, the acid value refers to the carboxyl group content. The carboxyl groups mentioned above include those in the carboxylate ion state, which are obtained by neutralizing the carboxyl group with a basic compound.

[0025] Next, we will describe each component contained in this release adhesive composition.

[0026] [Polyester resin (A)] The polyester resin (A) used in this release adhesive composition may be any commonly known polyester resin used in adhesives. The polyester resin (A) has structural units derived from dicarboxylic acids and diols, and optionally has structural units derived from trivalent or higher polycarboxylic acids and / or trivalent or higher polyhydric alcohols. Such a polyester resin (A) is obtained by polymerizing a polymerization component containing a polycarboxylic acid such as a dicarboxylic acid or a trivalent or higher polycarboxylic acid, and a polyhydric alcohol such as a diol or a trivalent or higher polyhydric alcohol.

[0027] [Structural units derived from dicarboxylic acids] Examples of dicarboxylic acid-derived structural units in the above polyester resin (A) include aliphatic acyclic dicarboxylic acids such as succinic acid, methylsuccinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, pimelic acid, decanedicarboxylic acid, octadecanedicarboxylic acid, 1,12-dodecanoic acid, 1,14-tetradecanoic acid, hydrogenated dimer acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexanediacetic acid, 1,3-cyclohexanediacetic acid, 1,4-cyclohexanediacetic acid, tetrahydrophthalic acid, tetrachlorophthalic acid, and he Examples include aliphatic cyclic dicarboxylic acids such as xahydrophthalic acid, aliphatic unsaturated dicarboxylic acids such as fumaric acid, maleic acid, itaconic acid, and dimer acids, benzene dicarboxylic acids such as terephthalic acid, isophthalic acid, and orthophthalic acid, aromatic dicarboxylic acids such as 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, franzicarboxylic acids, and heterocyclic dicarboxylic acids such as thiophene dicarboxylic acids (pyrrole, pyrazole, imidazole, pyridine, pyridazine, pyrimidine, pyrazine, etc.), as well as structural units derived from their acid anhydrides and lower alkyl esters. These dicarboxylic acid-derived structural units may be present individually or in pairs or more in the polyester resin (A). Among these, it is preferable to have structural units derived from aromatic dicarboxylic acids and structural units derived from aliphatic acyclic dicarboxylic acids. In particular, it is even preferable to have both structural units derived from aromatic dicarboxylic acids and structural units derived from aliphatic acyclic dicarboxylic acids, as this allows for both durability and flexibility. In particular, it is preferable to have both structural units derived from isophthalic acid and structural units derived from sebacic acid.

[0028] When the polyester resin (A) has structural units derived from aromatic dicarboxylic acids, the content of these units is preferably 5 to 75 mol%, and more preferably 10 to 30 mol%, of the structural units derived from polycarboxylic acids. If the content is too low, the heat resistance and mechanical strength tend to decrease, and if it is too high, flexibility is lost, the initial tackiness decreases, and the resin tends not to exhibit sufficient adhesive strength with pressure equivalent to finger pressure.

[0029] Furthermore, if the polyester resin (A) has structural units derived from aliphatic acyclic dicarboxylic acids, the content of these units is preferably 5 mol% or more of the structural units derived from polycarboxylic acids, more preferably 25 to 95 mol%, and more preferably 70 to 90 mol%. If the content is too low, flexibility is lost, the initial tackiness (tackiness before energy is applied) decreases, and the adhesive force tends not to be sufficient even with pressure equivalent to finger pressure. If the content is too high, heat resistance and mechanical strength tend to decrease.

[0030] Furthermore, when the polyester resin (A) has structural units derived from aromatic dicarboxylic acids and structural units derived from aliphatic acyclic dicarboxylic acids, the ratio of structural units derived from aliphatic acyclic dicarboxylic acids (mol%) to structural units derived from aromatic dicarboxylic acids (mol%) is preferably 0.1 to 50, more preferably 1 to 25, and particularly preferably 2 to 10, from the viewpoint of balancing tackiness and mechanical strength.

[0031] [Diol-derived structural units] Examples of diol-derived structural units in the above polyester resin (A) include linear aliphatic diols such as ethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and 1,18-octadecanediol, as well as propylene glycol, 1,3-propanediol, neopentyl glycol, 2-methyl-1,3-propanediol, and 1-methyl-1,3- Propanediol, 2-methyl-2-ethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,3,5-trimethyl-1,3-pentanediol, 2-methyl-1,6-hexanediol, 2-methyl- Aliphatic diols having hydrocarbon groups in their side chains, such as 1,8-octanediol, 2-methyl-1,9-nonanediol, dimer diol, 4-methyl-1,7-heptanediol, 3-methyl-1,6-hexanediol, 1-methyl-1,6-hexanediol, 4-methyl-1,9-nonanediol, 3-methyl-1,9-nonanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,3-cyclobutanediol, hydrogenated bisphenol A, and also Examples include structural units derived from aromatic diols such as ethylene oxide adducts and propionite adducts, bisphenol A, 9,9-bis(hydroxyphenyl)fluorene, 4,4'-thiodiphenol, 4,4'-methylenediphenol, 4,4'-dihydroxybiphenyl, o-,m-, and p-dihydroxybenzene, 2,5-naphthalenediol, p-xylenediol, and their ethylene oxide adducts and propylene oxide adducts. These diol-derived structural units may be present individually or in pairs or more within the polyester resin (A). Among these, it is preferable to have both structural units derived from linear aliphatic diols and structural units derived from aliphatic diols having hydrocarbon groups in their side chains, in order to control the glass transition temperature so as to prevent crystallization. In particular, it is especially preferable to have structural units derived from at least one selected from ethylene glycol, 1,4-butanediol, and 1,6-hexanediol as the linear aliphatic diol structural units, and structural units derived from at least one selected from neopentyl glycol and 2-butyl-2-ethyl-1,3-propanediol as the aliphatic diol having hydrocarbon groups in its side chains.

[0032] Furthermore, the diol-derived structural units may include those derived from polyester diols, polyether diols, polycaprolactone diols, polycarbonate diols, etc., in order to easily obtain polymers with the desired molecular weight.

[0033] Examples of the polyester diol-derived structural units mentioned above include those obtained by dehydrating diol components such as ethylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,10-decanediol, and octadecanediol, and dicarboxylic acid components such as succinic acid, methylsuccinic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, 1,12-dodecanoic acid, 1,14-tetradecanediic acid, terephthalic acid, isophthalic acid, or their acid anhydrides or lower alkyl esters, either individually or in mixture form. Examples of commercially available polyester diols used to introduce such structural units into polyester resins (A) include the polyester diols of 3-methyl-1,5-pentanediol and adipic acid, such as the trade names "Kuraray Polyol P-510," "Kuraray Polyol P-1010," "Kuraray Polyol P-2010," "Kuraray Polyol P-3010," and "Kuraray Polyol P-5010" [all manufactured by Kuraray Co., Ltd.].

[0034] Examples of structural units derived from the above-mentioned polyetherdiol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, obtained by ring-opening polymerization of ethylene oxide, propylene oxide, tetrahydrofuran, etc., and structural units derived from copolymers thereof such as copolymers of these. Examples of commercially available polyetherdiols used to introduce such structural units into polyester resins (A) include the trade names "Adeka Polyether P-400," "Adeka Polyether P-1000," "Adeka Polyether P-2000," and "Adeka Polyether P-3000" [all manufactured by Asahi Denka Kogyo Co., Ltd.], which are polyetherdiols obtained by adding propylene oxide to propylene glycol.

[0035] Examples of structural units derived from the polycaprolactone diol mentioned above include those derived from caprolactone-based polyester diols obtained by ring-opening polymerization of cyclic ester monomers such as ε-caprolactone and δ-valerolactone. Examples of commercially available polycaprolactone diols used to introduce such structural units into polyester resin (A) include the trade names "Praxel L205AL", "Praxel L212AL", "Praxel L220AL", "Praxel L220PL", and "Praxel L230AL" [all manufactured by Daicel Chemical Industries, Ltd.].

[0036] Examples of structural units derived from the polycarbonate diols mentioned above include carbonate diols such as propylene carbonate diol, hexamethylene carbonate diol, and 3-methylpentene carbonate diol, as well as structural units derived from polycarbonate diols obtained by de-alcoholization reactions of polyhydric alcohols such as ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, and 1,9-nonanediol with dialkyl carbonates such as diethylene carbonate and dimethyl carbonate. Examples of commercially available polycarbonate diols used to introduce such structural units into polyester resins (A) include the product names "PLACCEL CD205", "PLACCEL CD210", "PLACCEL CD220", "PLACCEL CD205PL", "PLACCEL CD210PL", and "PLACCEL CD220PL" [all manufactured by Daicel Chemical Industries, Ltd.].

[0037] When such polyester resin (A) has structural units derived from linear aliphatic diols, the content of these units is preferably 5 to 60 mol%, and more preferably 10 to 50 mol%, of the structural units derived from polyhydric alcohols. If the content is too low, the cohesive force tends to be insufficient, and if the content is too high, crystallinity tends to occur, and the adhesive properties tend to be insufficient.

[0038] Furthermore, if the polyester resin (A) has structural units derived from diols having hydrocarbon groups in their side chains, the content of these units is preferably 3 to 100 mol%, and more preferably 10 to 70 mol%, of the structural units derived from polyhydric alcohols. If the amount is too low, crystallization tends to occur, and the tackiness is more likely to disappear.

[0039] When the above polyester resin (A) has structural units derived from linear aliphatic diols and structural units derived from aliphatic diols having hydrocarbon groups in their side chains, the ratio of structural units derived from aliphatic diols having hydrocarbon groups in their side chains (mol%) to structural units derived from linear aliphatic diols (mol%) is preferably 0.1 to 100, more preferably 0.5 to 20, and particularly preferably 1 to 5, from the viewpoint of minimizing the appearance of crystallinity.

[0040] [Structural units derived from polycarboxylic acids with a valency of 3 or higher] Examples of structural units derived from trivalent or higher polycarboxylic acids in the above-mentioned polyester resin (A) include aromatic polycarboxylic acids such as trimellitic acid, trimesic acid, and pyromellitic acid; aliphatic polycarboxylic acids such as 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, and 1,2,3,4-butanetetracarboxylic acid; and structural units derived from their acid anhydrides and lower alkyl esters. One or more of these trivalent or higher polycarboxylic acid-derived structural units may be present in the polyester resin (A). Among these, from the viewpoint of appropriately controlling the degree of dispersion, it is preferable to have structural units derived from trivalent carboxylic acids, particularly structural units derived from trivalent aromatic carboxylic acids, and especially structural units derived from trimetic acid.

[0041] When the polyester resin (A) has structural units derived from polycarboxylic acids with a valency of 3 or higher, the content of these units is preferably 0.1 to 5 mol% of the polycarboxylic acid-derived structural units, from the viewpoint of durability before energy transfer when used as an adhesive, more preferably 0.1 to 2.5 mol%, and especially preferably 0.2 to 2 mol%. If the content is too low, the durability before energy transfer when used as an adhesive tends to decrease, and if it is too high, gelation occurs and the adhesive strength tends to decrease.

[0042] [Structural units derived from polyhydric alcohols of trivalent or higher valency] Examples of structural units derived from trivalent or higher polyhydric alcohols in the above-mentioned polyester resin (A) include aliphatic polyhydric alcohol-derived structural units such as trimethylolethane, trimethylolpropane, glycerin, pentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, 1,2,6-hexanetriol, pentaerythritol, and dipentaerythritol. These trivalent or higher polyhydric alcohol-derived structural units may be present individually or in pairs or in combination in the polyester resin (A). Among these, from the viewpoint of appropriately controlling the degree of dispersion, it is preferable to have structural units derived from trivalent aliphatic alcohols, and in particular, it is preferable to have structural units derived from trimethylolpropane.

[0043] Furthermore, if the polyester resin (A) has structural units derived from polyhydric alcohols of trivalent or higher, the content of these units is preferably 0.1 to 5 mol% of the polyhydric alcohol-derived structural units from the viewpoint of durability before energy transfer when used as an adhesive, more preferably 0.1 to 2.5 mol%, and especially preferably 0.2 to 2 mol%. If the content is too low, the durability before energy transfer when used as an adhesive tends to decrease, and if it is too high, gelation occurs and the adhesive strength tends to decrease.

[0044] The composition and composition ratio of the polyester resin (A) are as described above. 1 H-NMR measurement and13 It can be determined from the spectrum obtained by 1C-NMR measurement.

[0045] [Manufacturing of polyester resin (A)] The polyester resin (A) used in this release adhesive composition can be produced by polycondensation reaction using the above-mentioned polycarboxylic acid and polyhydric alcohol as raw materials, in the presence of a catalyst, by a known method. That is, since the polyester resin (A) is obtained by polycondensation reaction of a polycarboxylic acid and a polyhydric alcohol, it has structural sites derived from the polycarboxylic acid and structural units derived from the polyhydric alcohol. In the above polycondensation reaction, an esterification reaction or transesterification reaction is carried out first, followed by the polycondensation reaction. In cases where high molecular weight is not required, it may be produced by esterification reaction or transesterification reaction alone.

[0046] The preferred ratio of polycarboxylic acid to polyhydric alcohol is 1 to 3 equivalents of polyhydric alcohol per equivalent of polycarboxylic acid, particularly preferably 1.1 to 2.2 equivalents, and even more preferably 1.2 to 1.7 equivalents. If the proportion of polyhydric alcohol is too low, the acid value tends to increase, making it difficult to increase the molecular weight, and if it is too high, the yield tends to decrease.

[0047] [Esterification reaction, or transesterification reaction] In esterification or transesterification reactions, catalysts are typically used. Specifically, examples include titanium-based catalysts such as tetraisopropyl titanate and tetrabutyl titanate, antimony-based catalysts such as antimony trioxide, germanium-based catalysts such as germanium dioxide, and catalysts such as zinc acetate, manganese acetate, and dibutyltin oxide. One or more of these are used. Among these, antimony trioxide, tetrabutyl titanate, germanium dioxide, and zinc acetate are preferred due to the balance between high catalytic activity and the color of the resulting reactants.

[0048] The amount of the catalyst is preferably 1 to 10,000 ppm relative to the total copolymerization components (by weight), particularly preferably 10 to 5,000 ppm, and even more preferably 20 to 3,000 ppm. If the amount is too low, the polymerization reaction tends not to proceed sufficiently, and if it is too high, there is no advantage such as shortening the reaction time, and side reactions tend to occur.

[0049] The reaction temperature during esterification or transesterification reactions is preferably 200-300°C, particularly preferably 210-280°C, and even more preferably 220-260°C. If the reaction temperature is too low, the reaction tends not to proceed sufficiently, and if it is too high, side reactions such as decomposition tend to occur. In addition, although the reaction pressure is usually atmospheric pressure, it is also preferable to raise the reaction temperature by pressurizing the reaction to proceed more efficiently.

[0050] The reaction conditions for the polycondensation reaction, which is carried out after the esterification or transesterification reaction described above, are preferably such that an equivalent amount of the same catalyst used in the esterification or transesterification reaction is added, the reaction temperature is preferably 220-280°C, particularly preferably 230-270°C, and the reaction system is gradually reduced in pressure until the final reaction is carried out at 5 hPa or less. If the reaction temperature is too low, the reaction tends not to proceed sufficiently, and if it is too high, side reactions such as decomposition tend to occur.

[0051] In producing the polyester resin (A) of the present invention, it is preferable to depolymerize after the completion of the condensation reaction, as this effectively incorporates functional groups into the polyester resin (A). For depolymerization, the aforementioned polycarboxylic acids and polyhydric alcohols can be used, and it is preferable to use a polycarboxylic acid with a valency of 3 or higher and / or a polyhydric alcohol with a valency of 3 or higher. Dicarboxylic acids and diols can be used as needed.

[0052] The polycarboxylic acid or polyhydric alcohol added during depolymerization is preferably a diol or a polyhydric alcohol of three or more valents, as it can increase the hydroxyl group content, and is even more preferably a polyhydric alcohol of three or more valents, as it can increase the hydroxyl group content more efficiently. In particular, trimethylolpropane is preferred due to its high versatility.

[0053] The temperature during depolymerization is typically 150-260°C, and the reaction time is typically 10 minutes to 3 hours.

[0054] When the total polycarboxylic acid content of the polyester resin (A) is set to 100 mol%, it is preferable to carry out depolymerization using a depolymerization component of 20 mol% or less, more preferably 0.1 to 15 mol%, particularly preferably 0.5 to 10 mol%, and even more preferably 1 to 5 mol%.

[0055] By carrying out the reaction according to the above method, a polyester resin (A) can be obtained.

[0056] The number-average molecular weight (Mn) of the polyester resin (A) is preferably 5,000 or more, more preferably 8,000 to 100,000, and particularly preferably 10,000 to 80,000. If the number-average molecular weight is too small, sufficient cohesive force cannot be obtained as an adhesive, and heat resistance and mechanical strength tend to decrease. If it is too large, flexibility is lost, initial tackiness decreases, and sufficient adhesive strength cannot be achieved with pressure equivalent to finger pressure.

[0057] The weight-average molecular weight (Mw) of the polyester resin (A) is preferably 5,000 or more, particularly preferably 10,000 or more, and even more preferably 30,000 or more. The upper limit is usually 500,000. If the weight-average molecular weight is too low, sufficient cohesive force cannot be obtained as an adhesive, which tends to reduce heat resistance and mechanical strength, and make it easier for adhesive residue to occur when peeled off again. If it is too high, flexibility is lost, initial tackiness decreases, and it tends not to exhibit sufficient adhesive strength with pressure such as finger pressure.

[0058] The degree of dispersion (weight-average molecular weight / number-average molecular weight) of the polyester resin (A) is preferably 20 or less, more preferably 15 or less, and particularly preferably 10 or less. If the degree of dispersion is too high, adhesive residue due to low molecular weight components tends to occur more easily. However, a low degree of dispersion is not problematic.

[0059] As an indicator of dispersion, Mw / Mp (weight-average molecular weight / peak-top molecular weight) can also be used. A small Mw / Mp is preferable, preferably 10 or less, particularly preferably 3 or less, and most preferably 1.5 or less. When Mw / Mp is large, there is a tendency for adhesive residue to remain due to a large amount of low-molecular-weight components.

[0060] Furthermore, it is preferable that the above number-average molecular weight, weight-average molecular weight, and peak-top molecular weight do not contain low-molecular-weight components in order to reduce adhesive residue, and it is preferable that components with a molecular weight of 1000 or less constitute 10% or less, and even more preferably 5% or less.

[0061] The above-mentioned degree of dispersion and the ratio of low molecular weight components can be adjusted by the content of trivalent or higher polyhydric alcohol components and / or trivalent or higher polyhydric carboxylic acid components that constitute the polyester resin (A), the conditions of the condensation reaction (temperature, vacuum level, stirring, reaction time, etc.), and whether or not depolymerization is performed and under what conditions.

[0062] Note that the above number-average molecular weight and weight-average molecular weight are average molecular weights converted to standard polystyrene molecular weight. The measurements were taken using a high-performance liquid chromatograph (Waters Japan Co., Ltd., "Waters 2695 (separation module)" and "Waters 2414 (detector)") with a Shodex GPC KF-806L column (exclusion limit molecular weight: 2 × 10⁶). 7 Separation range: 100~2×10 7 The measurement was performed using three tubes connected in series, each with a theoretical plate count of 10,000 stages per tube, a filler material of styrene-divinylbenzene copolymer, and a filler particle size of 10 μm.

[0063] The glass transition temperature of the polyester resin (A) is preferably -100 to 30°C, particularly preferably -80 to -0°C, and especially preferably -70 to -20°C. If the glass transition temperature is too high, flexibility is lost, resulting in poor conformability to uneven surfaces and reduced initial tackiness, making it difficult to achieve sufficient adhesion with pressure equivalent to finger pressure. If the glass transition temperature is too low, mechanical strength and heat resistance tend to decrease. The above glass transition temperature (Tg) is measured using a differential scanning calorimeter.

[0064] Furthermore, it is more preferable that the polyester resin (A) does not crystallize, and even if crystallization occurs, the crystallization temperature is preferably 0°C or lower, and more preferably -30°C or lower, as the tack tends to disappear if the crystallization temperature is too high. The crystallization energy is also preferably as low as possible, preferably 35 J / g or lower, more preferably 20 J / g or lower, and even more preferably 15 J / g or lower, as the tack tends to disappear if the crystallization energy is too high. The crystallization energy mentioned above refers to the energy consumed when heating and melting a crystallized substance, and can be measured using a differential scanning calorimeter (DSC).

[0065] The above-mentioned polyester resin (A) preferably contains substantially no acidic groups. The acid value of the polyester resin (A) is preferably 10 mg KOH / g or less, more preferably 5 mg KOH / g or less, even more preferably 3 mg KOH / g or less, particularly preferably 1 mg KOH / g or less, and most preferably 0.5 mg KOH / g or less. If the acid value is too high, durability tends to decrease. The above acid value can be adjusted, for example, by increasing the proportion of polyhydric alcohols or adjusting the reaction conditions during esterification or transesterification reactions. The lower limit of the acid value is usually 0 mg KOH / g. The acid value of the above polyester resin (A) is determined by neutralization titration in accordance with JIS K0070. In this invention, the acid value refers to the carboxyl group content in the polyester resin (A). The carboxyl groups include those in the carboxylate ion state, which are obtained by neutralizing the carboxyl group with a basic compound.

[0066] The polyester resin (A) described above preferably contains hydroxyl groups. The hydroxyl value of the polyester resin (A) is usually 1 to 100 mg KOH / g, preferably 3 to 50 mg KOH / g, particularly preferably 5 to 40 mg KOH / g, and even more preferably 15 to 30 mg KOH / g. If the hydroxyl value is too low, when introducing unsaturated groups into the polyester resin (A), the number of hydroxyl groups that react with the crosslinking agent (B) decreases as they react with the hydroxyl groups of the polyester resin (A), and the reactivity with the crosslinking agent (B) tends to decrease. Also, since it is usually necessary to lower the molecular weight in order to increase the hydroxyl value, if the hydroxyl value is too high, low molecular weight components tend to cause adhesive residue. In this invention, the hydroxyl value (mgKOH / g) is determined by dissolving 1 g of polyester resin (A) in 30 g of a mixed solvent of toluene / pyridine = 5 / 5 (weight ratio) and performing a neutralization titration according to JIS K0070.

[0067] The ester group concentration of the polyester resin (A) is preferably 1 to 12 mmol / g, more preferably 3 to 11 mmol / g, and even more preferably 5 to 10 mmol / g. If the ester group concentration is too low, the polarity and elastic modulus of the polyester resin (A) decrease, which tends to result in poor initial adhesion. If it is too high, the polarity increases too much, which tends to result in poor solution stability.

[0068] The ester group concentration (mmol / g) mentioned above refers to the number of moles of ester groups in 1g of polyester resin (A), and can be calculated, for example, from the amount used. This calculation method involves dividing the number of moles of the polycarboxylic acid and polyol, whichever is smaller, by the total weight of the finished product. An example of the calculation formula is shown below. In addition, when the charged amounts of the polyvalent carboxylic acid and the polyhydric alcohol are the same molar amount, either of the following calculation formulas may be used. Also, when using a monomer having both a carboxylic acid and a hydroxyl group, or preparing a polyester from caprolactone or the like, the calculation method will be changed as appropriate.

[0069] <When the polyvalent carboxylic acid is less> Ester group concentration (mmol / g) = [((A1 / α1 × m1 + A2 / α2 × m2 + A3 / α3 × m3 ···) / Z)] × 1000 A: Charged amount of polyvalent carboxylic acid (g) α: Molecular weight of polyvalent carboxylic acid m: Number of carboxyl groups per molecule of polyvalent carboxylic acid Z: Final weight (g)

[0070] <When the polyhydric alcohol is less> Ester group concentration (mmol / g) = [((B1 / β1 × n1 + B2 / β2 × n2 + B3 / β3 × n3 ···) / Z)] × 1000 B: Charged amount of polyhydric alcohol (g) β: Molecular weight of polyhydric alcohol n: Number of hydroxyl groups per molecule of polyhydric alcohol Z: Final weight (g)

[0071] Also, the above ester group concentration can also be measured by a known method using NMR or the like. For example, the determination of the ester group concentration, composition, and composition ratio of the polyester resin (A) is carried out by 1 1H-NMR measurement (proton nuclear magnetic resonance spectroscopy) with a resonance frequency of 400 MHz, 13 13C-NMR measurement (carbon nuclear magnetic resonance spectroscopy).

[0072] 〔Unsaturated group-containing polyester resin (A1)〕 In order to set the unsaturated group concentration of this release adhesive composition within the desired range, as described above, it is preferable to introduce unsaturated groups into the polyester resin (A), that is, to use an unsaturated group-containing polyester resin (A1) into which unsaturated groups have been introduced, as this increases the cohesive force after energy transfer when used as an adhesive and reduces the adhesive force. The above-mentioned unsaturated group-containing polyester resin (A1) may be any polyester resin that contains an ethylenically unsaturated group in its structure. Preferably, the polyester resin (A) contains an ethylenically unsaturated group at the end of the main chain or the end of the side chain. More preferably, the polyester resin (A) contains an ethylenically unsaturated group at the end of the main chain, as this allows for a larger molecular weight between crosslinking points.

[0073] A method for introducing ethylenically unsaturated groups into the above-mentioned polyester resin (A) to obtain an unsaturated group-containing polyester resin (A1) is as follows: (1) A method of introducing ethylenically unsaturated groups into a polyester resin (A) after it has been manufactured. (2) A method of copolymerizing monomers containing ethylenically unsaturated groups, such as fumaric acid and maleic acid, as polymerization components constituting a polyester resin (A), While these methods are possible, method (1) is preferred because it allows for the easy introduction of highly reactive (meth)acryloyl groups and offers good polymerization stability. The preferred method (1) will be described below.

[0074] As for the method described in (1) above, for example, a compound containing an ethylenically unsaturated group having a functional group that reacts with the functional group at the end of the main chain or the side chain of the polyester resin (A) may be reacted with the functional group. In particular, reacting the compound containing an ethylenically unsaturated group with the functional group at the end of the main chain of the polyester resin (A) is preferable because it can increase the molecular weight between crosslinking points of the resulting unsaturated group-containing polyester resin (A1) and thereby increase its elongation.

[0075] (Compounds containing ethylenically unsaturated groups) The ethylenically unsaturated group in the above-mentioned ethylenically unsaturated compound is preferably a (meth)acryloyl group, as this group is more likely to harden when energy is applied.

[0076] Examples of the ethylenically unsaturated group-containing compounds mentioned above include hydroxyl group-containing (meth)acrylates, carboxyl group-containing (meth)acrylates, amino group-containing (meth)acrylates, acetoacetyl group-containing (meth)acrylates, isocyanate group-containing (meth)acrylates, and glycidyl group-containing (meth)acrylates. These may be used individually or in combination of two or more.

[0077] Examples of the above hydroxyl group-containing (meth)acrylates include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalate, 2-hydroxy-3-(meth)acryloyloxypropyl (meth)acrylate, caprolactone-modified 2-hydroxyethyl (meth)acrylate, etc., which contain ethylenically unsaturated groups. Examples include hydroxyl group-containing (meth)acrylates having one hydroxyl group, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, caprolactone-modified dipentaerythritol penta(meth)acrylate, caprolactone-modified pentaerythritol tri(meth)acrylate, ethylene oxide-modified dipentaerythritol penta(meth)acrylate, and ethylene oxide-modified pentaerythritol tri(meth)acrylate, which have two or more ethylenically unsaturated groups. Among these, hydroxyl group-containing (meth)acrylates having two or more ethylenically unsaturated groups are preferred. Furthermore, these can be used individually or in combination of two or more.

[0078] Examples of the isocyanate group-containing (meth)acrylates mentioned above include 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate, 1,1-(bisacryloyloxymethyl)ethyl isocyanate, 1,1-(bismecryloyloxymethyl)ethyl isocyanate, and their alkylene oxide adducts. These can be used individually or in combination of two or more.

[0079] Furthermore, as isocyanate group-containing (meth)acrylates, urethane (meth)acrylate-type isocyanate group-containing unsaturated oligomers, which are reaction products of isocyanate compounds such as tolylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, or their adducts or isocyanurates, with the hydroxyl group-containing (meth)acrylates mentioned above, or compounds having a hydroxyl group and multiple (meth)acryloyl groups, can also be used. Furthermore, these can be used individually or in combination of two or more types.

[0080] The ethylenically unsaturated group-containing compound described above is appropriately selected depending on the reactivity of the functional group of the polyester resin (A) and the functional group of the ethylenically unsaturated group-containing compound. For example, if the functional group of the polyester resin (A) is a carboxyl group, it is preferable to use a glycidyl group-containing (meth)acrylate, an isocyanate group-containing (meth)acrylate, or a hydroxyl group-containing (meth)acrylate as the ethylenically unsaturated group-containing compound. Furthermore, if the functional group of the polyester resin (A) is a hydroxyl group, it is preferable to use an isocyanate group-containing (meth)acrylate or a carboxyl group-containing (meth)acrylate monomer as the ethylenically unsaturated group-containing compound. In particular, when the functional group of the polyester resin (A) is a hydroxyl group, it is preferable to use an isocyanate-containing (meth)acrylate as the ethylenically unsaturated group-containing compound because it is easier to control the reaction, and 2-methacryloyloxyethyl isocyanate is especially preferred.

[0081] Thus, by reacting a polyester resin (A) with an ethylenically unsaturated group-containing monomer by a conventional method, an unsaturated group-containing polyester resin (A1) is obtained.

[0082] Furthermore, when a polyester resin (A) is reacted with an isocyanate group-containing (meth)acrylate to produce an unsaturated group-containing polyester resin (A1), it is preferable to react the isocyanate group-containing (meth)acrylate so that 5 to 95 mol% of the hydroxyl groups present in the polyester resin (A) are consumed, and more preferably 10 to 80 mol%, even more preferably 20 to 70 mol%, and especially preferably 30 to 60 mol% are consumed. If the amount of hydroxyl groups consumed is too small, the unsaturated group concentration will be low, and the reduction in tackiness after energy transfer will be insufficient. If the amount consumed is too large, the reaction with the crosslinking agent (B) will be less likely to occur, and adhesive residue will tend to remain.

[0083] The unsaturated group concentration of the above-mentioned unsaturated group-containing polyester resin (A1) is preferably 0.001 to 2 mmol / g per 1 g of the unsaturated group-containing polyester resin (A1), more preferably 0.01 to 1.5 mmol / g, and particularly preferably 0.05 to 0.5 mmol / g. If the concentration of unsaturated groups in the unsaturated group-containing polyester resin (A1) is too low, the reduction in adhesive strength after energy transfer tends to be insufficient, and the re-peelability and resistance to substrate contamination tend to decrease. If the concentration is too high, the elongation after energy transfer tends to decrease. The unsaturated groups contained in the above unsaturated group-containing polyester resin (A1) are as described above. 1 H-NMR measurement and 13 It can be determined from the spectrum obtained by 1C-NMR measurement.

[0084] The unsaturated group-containing polyester resin (A1) described above preferably contains hydroxyl groups. The hydroxyl value of the unsaturated group-containing polyester resin (A1) is preferably 1 to 95 mg KOH / g, more preferably 2 to 40 mg KOH / g, particularly preferably 3 to 30 mg KOH / g, and especially preferably 5 to 15 mg KOH / g. If the hydroxyl value is too low, there will be insufficient hydroxyl groups to react with the crosslinking agent (B), leading to decreased reactivity with the crosslinking agent (B) and a tendency for adhesive residue to form. Conversely, increasing the hydroxyl value requires lowering the molecular weight or reducing the amount of unsaturated groups introduced. Therefore, if the hydroxyl value is too high, low molecular weight components and insufficient unsaturated groups tend to be the cause of adhesive residue.

[0085] [Crosslinking agent (B)] The crosslinking agent (B) used in this release adhesive composition can be any compound having a functional group that reacts with the functional group contained in the polyester resin (A). Examples include epoxy compounds such as bisphenol A-epichlorohydrin type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl erythritol, diglycerol polyglycidyl ether, tetramethylolmethane-tri-β-azilidinylpropionate, trimethylolpropane-tri-β-azilidinylpropionate, and N,N'-di Aziridine compounds such as phenylmethane-4,4'-bis(1-aziridinecarboxamide) and N,N'-hexamethylene-1,6-bis(1-aziridinecarboxamide), melamine compounds such as hexamethoxymethylmelamine, hexaethoxymethylmelamine, hexapropoxymethylmelamine, hexapoxymethylmelamine, hexapentyloxymethylmelamine, hexahexyloxymethylmelamine, and melamine resin, 2,4-tolylenediisocyanate, 2,6-tolylenediisocyanate, hydrogenated tolylenediisocyanate, 1,3-xylylenediisocyanate, 1,4-xylylenediisocyanate, hexamethylenediisocyanate, diphenylmethane-4,4-diisocyanate, isophorone diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, tetramethylxylylenediisocyanate, 1,Examples include 5-naphthalene diisocyanate, triphenylmethane triisocyanate, and adduct compounds of these polyisocyanate compounds with polyol compounds such as trimethylolpropane, isocyanate compounds such as biuret and isocyanurate forms of these polyisocyanate compounds, aldehyde compounds such as glyoxal, malondialdehyde, succinidaldehyde, maleidaldehyde, glutardialdehyde, formaldehyde, acetaldehyde, and benzaldehyde, amine compounds such as hexamethylenediamine, triethyldiamine, polyethyleneimine, hexamethylenetetraamine, diethylenetriamine, triethyltetraamine, isophoronediamine, amino resins, and polyamides, and metal chelate compounds such as acetylacetone and acetoacetyl ester coordination compounds of polymetals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium. In particular, isocyanate compounds are preferably used due to their ability to provide good adhesion to the substrate and their reactivity with polyester resin (A). These crosslinking agents (B) may be used individually or in combination of two or more.

[0086] Furthermore, as the crosslinking agent (B), in addition to the above, it is preferable to use a compound that has a functional group that reacts with the functional group contained in the polyester resin (A) and also contains an unsaturated group, in order to increase the concentration of unsaturated groups in the release adhesive composition. Examples of such compounds include polyisocyanates and epoxy containing (meth)acryloyl groups in the side chain, and among these, polyisocyanates containing (meth)acryloyl groups in the side chain are preferred.

[0087] The polyisocyanates containing (meth)acryloyl groups in the side chains are not particularly limited, but examples include compounds obtained by reacting a polyisocyanate with a hydroxyl group-containing (meth)acrylic compound to produce a urethane (meth)acrylate with an isocyanate group remaining, and then allophanating those compounds, or compounds obtained by reacting one isocyanate group of a trifunctional or more polyisocyanate with a hydroxyl group-containing (meth)acrylate compound. Among these, allophanated compounds are preferred because they allow for stable possession of (meth)acryloyl groups in the side chains.

[0088] The above polyisocyanates are not particularly limited and include, for example, aromatic, aliphatic, and alicyclic polyisocyanates, among which tolylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, polyphenylmethane polyisocyanate, modified diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, tetramethylxylylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, and phenylene diisocyanate. Examples include polyisocyanates such as phosphate, lysine diisocyanate, lysine triisocyanate, and naphthalene diisocyanate, or trimer compounds or polymer compounds of these polyisocyanates, burette-type polyisocyanates, water-dispersible polyisocyanates (for example, "Aquanate 100," "Aquanate 110," "Aquanate 200," and "Aquanate 210" manufactured by Nippon Polyurethane Industries Co., Ltd.), or reaction products of these polyisocyanates with polyols. Among these, tolylene diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate are preferred due to their high versatility, with hexamethylene diisocyanate being the most preferred. These can be used individually or in combination of two or more.

[0089] Examples of the hydroxyl group-containing (meth)acrylic compounds mentioned above include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalate, 2-hydroxy-3-(meth)acryloyloxypropyl (meth)acrylate, caprolactone-modified 2-hydroxyethyl (meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, caprolactone-modified dipentaerythritol penta(meth)acrylate, caprolactone-modified pentaerythritol tri(meth)acrylate, ethylene oxide-modified dipentaerythritol penta(meth)acrylate, and ethylene oxide-modified pentaerythritol tri(meth)acrylate. These can be used individually or in combination of two or more types.

[0090] Specifically, examples include compounds represented by the following general formula (1).

[0091] [ka]

[0092] In the formula, n represents a positive integer, for example, 20 or less, preferably between 1 and 5. The above R1 is hydrogen or a methyl group, preferably hydrogen. The above R2 is an organic chain containing at least one selected from C, O, N, and S. Specifically, examples include -COO-, -CO-, -O-, alkylene chains, and oxyalkylene chains, and these may be combined in two or more ways. Among these, combinations of -COO- or -CO- with alkylene chains are preferred, and combinations of -COO- with alkylene chains are particularly preferred. Examples of the alkylene chains include alkylene chains having 1 to 10 carbon atoms, and alkylene chains having 1 to 5 carbon atoms are particularly preferred. Examples of the oxyalkylene chains include oxyethylene chains, oxypropylene chains, and oxybutylene chains. Two or more types of oxyethylene chains may be combined, and each oxyalkylene chain may have repeating units. In the case of repeating units, a total of 2 to 20 repeating units is preferred.

[0093] Each of the above R3 and R4 is a bond chain that independently contains at least one selected from C, O, N, and S, and is preferably a part of the trunk of the above polyisocyanate such as methyltoluene, isophorone, or hexamethylene, or a combination of the trunk of such polyisocyanate and -NHCO-.

[0094] The structure of the most preferred crosslinking agent (B) is shown below.

[0095] [ka]

[0096] The amount of crosslinking agent (B) can be appropriately selected depending on the amount of functional groups contained in the polyester resin (A), the molecular weight of the polyester resin (A), and the purpose of controlling the adhesive strength and elongation after irradiation with active energy rays. However, it is usually preferable to have 0.1 to 20 parts by weight, more preferably 0.2 to 15 parts by weight, and particularly preferably 0.5 to 10 parts by weight, per 100 parts by weight of the polyester resin (A).

[0097] If there is too little crosslinking agent (B), the cohesive force will be insufficient and sufficient durability will not be obtained. If there is too much, the flexibility before energy transfer will decrease and the adhesive strength will decrease.

[0098] In the present invention, when (X) is the concentration of functional groups that react with the crosslinking agent (B) of the polyester resin (A) [excluding unsaturated groups present in the polyester resin (A)] (mmol / g), and (Y) is the concentration of functional groups in the crosslinking agent (B) that react with the functional groups of the polyester resin (A) (mmol / g), then 0.1 ≤ (Y) / (X) ≤ 3.0 is preferable in that the adhesive network after energy transfer becomes unified, 0.2 ≤ (Y) / (X) ≤ 2.0 is more preferable, and 0.5 ≤ (Y) / (X) ≤ 1.5 is particularly preferable. If the functional group concentration of the crosslinking agent (B) is too high, bubbles and the like tend to form when it is used as an adhesive layer, resulting in a poor appearance. If it is too low, the overall network becomes loose, which tends to cause adhesive residue.

[0099] Furthermore, using both a crosslinking agent (B) containing unsaturated groups and one without is preferable for controlling the cohesive force before and after energy transfer.

[0100] [Polymerization initiator (C)] This release adhesive composition is preferable in that it contains a polymerization initiator (C) which can stabilize the curing reaction when peeled from the adherend.

[0101] Various polymerization initiators such as photopolymerization initiators (C1) and thermal polymerization initiators (C2) can be used as the polymerization initiator (C) mentioned above, but the use of a photopolymerization initiator (C1) is particularly preferred because it allows curing by applying energy such as ultraviolet light for a very short time.

[0102] The photopolymerization initiator (C1) is not particularly limited as long as it generates radicals upon the action of light, for example, diethoxyacetophenone, 2-hydroxy-1-[4-[4-(2-hydroxy-2-methylpropionyl)benzyl]phenyl]-2-methylpropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethyl ketal, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexylphenyl ketone, 2 Acetophenones such as -methyl-2-morpholino(4-thiomethylphenyl)propan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone oligomer; benzoins such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether; benzophenone, o-methyl benzoylbenzoate, 4-phenylbenzophenone, Benzophenones such as 4-benzoyl-4'-methyl-diphenyl sulfide, 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone, 2,4,6-trimethylbenzophenone, 4-benzoyl-N,N-dimethyl-N-[2-(1-oxo-2-propenyloxy)ethyl]benzenemethanaminonium bromide, (4-benzoylbenzyl)trimethylammonium chloride; 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4 Examples include thioxanthones such as dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, and 2-(3-dimethylamino-2-hydroxy)-3,4-dimethyl-9H-thioxanthone-9-one mesochloride; and acylphosphon oxides such as 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide. These photopolymerization initiators (C1) may be used individually or in combination of two or more.

[0103] Among these, it is preferable to use 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-1-[4-[4-(2-hydroxy-2-methylpropionyl)benzyl]phenyl]-2-methylpropan-1-one, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, or benzyldimethyl ketal.

[0104] Furthermore, triethanolamine, triisopropanolamine, 4,4'-dimethylaminobenzophenone (Michler ketone), 4,4'-diethylaminobenzophenone, 2-dimethylaminoethylbenzoic acid, 4-dimethylaminobenzoate ethyl, 4-dimethylaminobenzoate (n-butoxy)ethyl, 4-dimethylaminobenzoate isoamyl, 4-dimethylaminobenzoate 2-ethylhexyl, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, etc. can also be used in combination as auxiliary agents for the photopolymerization initiator (C1).

[0105] Furthermore, as the above thermal polymerization initiator (C2), for example, methyl ethyl ketone peroxide, cyclohexanone peroxide, methylcyclohexanone peroxide, methyl acetacetate peroxide, acetylacetate peroxide, 1,1-bis(t-hexyl peroxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-hexyl peroxy)-cyclohexane, 1,1-bis(t-butyl peroxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-butyl peroxy)-2-methylcyclohexane, 1,1-Bis(t-butylperoxy)-cyclohexane, 1,1-Bis(t-butylperoxy)cyclododecane, 1,1-Bis(t-butylperoxy)butane, 2,2-Bis(4,4-di-t-butylperoxycyclohexyl)propane, p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, t-hexyl hydroperoxide, t-butyl hydroperoxide, α,α'-Bis(t-butylperoxy) Diisopropylbenzene, dicumyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, t-butylcumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyn-3, isobutyryl peroxide, 3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, succinate peroxide, m-toluylbenzoyl peroxide, benzoyl peroxide, di- n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, bis(4-t-butylcyclohexyl) peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate, di-2-ethoxyhexyl peroxydicarbonate, di-3-methoxybutyl peroxydicarbonate, di-s-butyl peroxydicarbonate, di(3-methyl-3-methoxybutyl) peroxydicarbonate, α,α'-bis(neodecanoylperoxy)diisopropylbenzene, cumyl peroxyneodecanoate, 1,1,3,3-Tetramethylbutyl peroxyneodecanoate, 1-Cyclohexyl-1-methylethyl peroxyneodecanoate, t-Hexyl peroxyneodecanoate, t-Butyl peroxyneodecanoate, t-Hexyl peroxypivalate, t-Butyl peroxypivalate, 1,1,3,3-Tetramethylbutyl peroxy-2-ethylhexanoate, 2,5-Dimethyl-2,5-Bis(2-ethylhexanoyl peroxy)hexanoate, 1-Cyclohexyl-1-methylethyl peroxy-2-ethylhexanoate t-Hexylperoxy-2-ethylhexanoate, t-Butylperoxy-2-ethylhexanoate, t-Hexylperoxyisopropyl monocarbonate, t-Butylperoxyisobutyrate, t-Butylperoxymalate, t-Butylperoxy-3,5,5-trimethylhexanoate, t-Butylperoxylaurate, t-Butylperoxyisopropyl monocarbonate, t-Butylperoxy-2-ethylhexyl monocarbonate, t-Butylperoxyacetate, t-Butylperoxy-m-Tol Organic peroxides such as ylbenzoates, t-butyl peroxybenzoates, bis(t-butyl peroxy) isophthalates, 2,5-dimethyl-2,5-bis(m-tolyl peroxy)hexane, t-hexyl peroxybenzoates, 2,5-dimethyl-2,5-bis(benzoyl peroxy)hexane, t-butyl peroxyallyl monocarbonate, t-butyl trimethylsilyl peroxide, 3,3',4,4'-tetra(t-butyl peroxycarbonyl) benzophenone, and 2,3-dimethyl-2,3-diphenylbutane. System initiators; 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile, 1-[(1-cyano-1-methylethyl)azo]formamide, 1,1'-azobis(cyclohexane-1-carbonitride), 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylpropionamidine)dihydrochloride, 2,2'-azobis(2-methyl-N-phenylpropionamidine)dihydrochloride, 2,2'-Azobis[N-(4-chlorophenyl)-2-methylpropionamidine]dihydrochloride, 2,2'-Azobis[N-(4-hydrophenyl)-2-methylpropionamidine]dihydrochloride, 2,2'-Azobis[2-methyl-N-(phenylmethyl)propionamidine]dihydrochloride, 2,2'-Azobis[2-methyl-N-(2-propenyl)propionamidine]dihydrochloride, 2,2'-Azobis[N-(2-hydroxyethyl)-2-methylpropionamidine 2,2'-Azobis[2-(5-methyl-2-imidazolin-2-yl)propane]dihydrochloride, 2,2'-Azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride, 2,2'-Azobis[2-(4,5,6,7-tetrahydro-1H-1,3-diazepine-2-yl)propane]dihydrochloride, 2,2'-Azobis[2-(3,4,5,6-tetrahydropyrimidine-2-yl)propane]dihydrochloride, 2,2'-Azobis[2-(5 -Hydroxy-3,4,5,6-tetrahydropyrimidine-2-yl)propane]dihydrochloride, 2,2'-azobis[2-[1-(2-hydroxyethyl)-2-imidazolin-2-yl]propane]dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane], 2,2'-azobis[2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide], 2,2'-azobis[2-methyl-N-[1,1-bis(hydroxymethyl Examples of azo-based initiators include [(2-(hydroxymethyl)propionamide)], 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide], 2,2'-azobis(2-methylpropionamide), 2,2'-azobis(2,4,4-trimethylpentane), 2,2'-azobis(2-methylpropane), dimethyl-2,2-azobis(2-methylpropionate), 4,4'-azobis(4-cyanopentanoic acid), and 2,2'-azobis[2-(hydroxymethyl)propionitrile]. These thermal polymerization initiators (C2) may be used individually or in combination of two or more.

[0106] The content of the polymerization initiator (C) is preferably 0.01 to 10 parts by weight, particularly preferably 0.1 to 5 parts by weight, and even more preferably 0.3 to 2 parts by weight, per 100 parts by weight of the polyester resin (A). If the amount is too small, curing tends to be insufficient, and if it is too large, there is a concern that the polymerization initiator (C) will become an adhesive residue.

[0107] [Hydrolysis inhibitor (D)] The hydrolysis inhibitor (D) is not particularly limited, and conventionally known compounds can be used. For example, compounds that react and bond with the carboxyl group terminals of the polyester resin (A) can be used. Specifically, compounds having functional groups such as carbodiimide groups, epoxy groups, or oxazoline groups can be used. Among these, carbodiimide group-containing compounds are preferred because they have a high effect in eliminating the catalytic activity of protons derived from carboxyl group terminals.

[0108] As the carbodiimide group-containing compound used in this peelable adhesive composition, a known carbodiimide having one or more carbodiimide groups (-N=C=N-) in its molecule can usually be used. However, to improve durability under high temperature and high humidity conditions, a compound containing two or more carbodiimide groups in its molecule, i.e., a polyvalent carbodiimide compound, is preferred, and in particular, a compound containing three or more carbodiimide groups in its molecule, more preferably five or more, and especially seven or more. The number of carbodiimide groups in a molecule is usually 50 or less. If there are too many carbodiimide groups, the molecular structure becomes too large, which tends to reduce compatibility.

[0109] From the viewpoint of hydrolysis resistance, it is preferable to use a carbodiimide group-containing compound with a high weight-average molecular weight. The weight-average molecular weight of the carbodiimide group-containing compound is preferably 1000 or more, more preferably 2000 or more, and even more preferably 3000 or more. The upper limit of the weight-average molecular weight is usually 50000.

[0110] Furthermore, it is preferable to use a carbodiimide group-containing compound that has low volatility, and for that reason, it is preferable to use one with a high number-average molecular weight, which is usually 300 to 10000, and preferably 1000 to 5000.

[0111] If the molecular weight of a carbodiimide group-containing compound is too low, its hydrolysis resistance tends to decrease. Conversely, if the molecular weight is too high, its compatibility with polyester resin (A) tends to decrease.

[0112] The carbodiimide equivalent of the above carbodiimide group-containing compound is preferably 50 to 10000, particularly preferably 100 to 1000, and even more preferably 150 to 500. Note that the carbodiimide equivalent refers to the chemical formula weight per carbodiimide group.

[0113] Furthermore, as the carbodiimide group-containing compound, it is also preferable to use a polycarbodiimide compound produced by decarboxylating and condensing diisocyanate in the presence of a carbodiimide catalyst.

[0114] (Polycarbodiimide compounds) Polycarbodiimide compounds can be obtained by condensation reactions of organic diisocyanate compounds. Examples of the above organic diisocyanate compounds include aromatic diisocyanate compounds such as 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, xylylene diisocyanate, and tetramethylxylylene diisocyanate; Examples include acyclic aliphatic diisocyanates such as hexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, methylcyclohexane diisocyanate, and aliphatic diisocyanates such as cyclic aliphatic diisocyanates such as 2,5(2,6)-bis(isocyanatomethyl)bicyclo[2.2.1]heptane; and so on. These may be used individually or in combination of two or more. In particular, aromatic diisocyanate compounds are preferred, and tetramethylxylene diisocyanate is more preferred, as they can be used to create a pressure-sensitive adhesive composition with excellent resistance to moisture and heat.

[0115] By decarboxylating and condensing the above-mentioned organic diisocyanate compound using a known carbodiimide catalyst in a conventional manner, a polycarbodiimide compound can be obtained.

[0116] The above polycarbodiimide compounds are preferably aromatic polycarbodiimide compounds because they exhibit minimal haze change even under high temperature and high humidity conditions, and can be used as adhesives with excellent resistance to humid heat.

[0117] Examples of commercially available polycarbodiimide compounds include Carbodilite® V-09GB, V-02B, V-04K, V-04PF, and V-07 manufactured by Nisshinbo Chemical Corporation, and Elastostab H01 manufactured by BASF, among which Carbodilite V-09GB is preferred.

[0118] As the epoxy group-containing compound, for example, glycidyl ester compounds and glycidyl ether compounds are preferred.

[0119] Examples of the above glycidyl ester group-containing compounds include glycidyl benzoate, t-bu-glycidyl benzoate, p-glycidyl toluate, glycidyl cyclohexanecarboxylic acid, glycidyl pelargonic acid, glycyl stearate, glycidyl laurate, glycidyl palmitate, glycidyl behenate, glycidyl versatic acid, glycidyl oleate, glycidyl linoleate, glycidyl linoleate, glycidyl behenolate, glycidyl stearolate, diglycidyl terephthalate, and diisophthalate. Examples include glycidyl esters, diglycidyl phthalates, diglycidyl naphthalenedicarboxylic acid, diglycidyl methylterephthalate, diglycidyl hexahydrophthalate, diglycidyl tetrahydrophthalate, diglycidyl cyclohexanedicarboxylic acid, diglycidyl adipic acid, diglycidyl succinate, diglycidyl sebacate, diglycidyl dodecandionate, diglycidyl octadecanedicarboxylic acid, triglycidyl trimellitic acid, tetraglycidyl pyromellitic acid, etc., which can be used alone or in combination of two or more.

[0120] Examples of the glycidyl ether group-containing compounds mentioned above include phenylglycidyl ether, o-phenylglycidyl ether, 1,4-bis(β,γ-epoxypropoxy)butane, 1,6-bis(β,γ-epoxypropoxy)hexane, 1,4-bis(β,γ-epoxypropoxy)benzene, 1-(β,γ-epoxypropoxy)-2-ethoxyethane, 1-(β,γ-epoxypropoxy)-2-benzyloxyethane, 2,2-bis-[r-(β,γ-epoxypropoxy)phenyl]propane, and bisglycidyl polyethers obtained by the reaction of bisphenols such as 2,2-bis-(4-hydroxyphenyl)propane and 2,2-bis-(4-hydroxyphenyl)methane with epichlorohydrin. These can be used alone or in combination of two or more.

[0121] As the oxazoline group-containing compound, bisoxazoline compounds are preferred. Specifically, for example, 2,2'-bis(2-oxazoline), 2,2'-bis(4-methyl-2-oxazoline), 2,2'-bis(4,4-dimethyl-2-oxazoline), 2,2'-bis(4-ethyl-2-oxazoline), 2,2'-bis(4,4'-diethyl-2-oxazoline), 2,2'-bis(4-propyl-2-oxazoline), 2,2'-bis(4-butyl-2-oxazoline), and 2,2'-bis(4-hexyl-2-oxazoline) are preferred. ), 2,2'-bis(4-phenyl-2-oxazoline), 2,2'-bis(4-cyclohexyl-2-oxazoline), 2,2'-bis(4-benzyl-2-oxazoline), 2,2'-p-phenylenebis(2-oxazoline), 2,2'-m-phenylenebis(2-oxazoline), 2,2'-o-phenylenebis(2-oxazoline), 2,2'-p-phenylenebis(4-methyl-2-oxazoline), 2,2'-p-phenylenebis(4,4 2,2'-dimethyl-2-oxazoline), 2,2'-m-phenylenebis(4-methyl-2-oxazoline), 2,2'-m-phenylenebis(4,4-dimethyl-2-oxazoline), 2,2'-ethylenebis(2-oxazoline), 2,2'-tetramethylenebis(2-oxazoline), 2,2'-hexamethylenebis(2-oxazoline), 2,2'-octamethylenebis(2-oxazoline), 2,2'-decamethylenebis(2-oxazoline), 2 Examples include 2'-ethylenebis(4-methyl-2-oxazoline), 2,2'-tetramethylenebis(4,4-dimethyl-2-oxazoline), 2,2'-9,9'-diphenoxyethanebis(2-oxazoline), 2,2'-cyclohexylenebis(2-oxazoline), and 2,2'-diphenylenebis(2-oxazoline). Among these, 2,2'-bis(2-oxazoline) is the most preferred from the viewpoint of reactivity with polyester. Furthermore, the bisoxazoline compounds listed above can be used individually or in combination of two or more, as long as they achieve the objectives of the present invention.

[0122] These hydrolysis inhibitors (D) are preferably low in volatility, and therefore, it is preferable to use those with a high molecular weight.

[0123] The amount of the hydrolysis inhibitor (D) is preferably 0.01 to 10 parts by weight, particularly preferably 0.1 to 5 parts by weight, and even more preferably 0.2 to 3 parts by weight, per 100 parts by weight of the polyester resin (A). If the amount is too high, turbidity tends to occur due to poor compatibility with the polyester resin (A), and if it is too low, sufficient durability tends to be difficult to obtain.

[0124] Furthermore, the amount of hydrolysis inhibitor (D) is preferably optimized according to the acid value of the polyester resin (A). The molar ratio ((ii) / (i)) of the total number of carboxyl groups (i) determined from the acid value of the polyester resin (A) in the polyester resin composition to the total number of functional groups (ii) of the hydrolysis inhibitor (D) in the polyester resin composition is preferably 0.5 ≤ (ii) / (i), particularly preferably 1 ≤ (ii) / (i) ≤ 1000, and even more preferably 1.5 ≤ (ii) / (i) ≤ 100. If the ratio of (ii) to (i) is too high, compatibility with polyester resin (A) tends to decrease, and adhesive strength, cohesive strength, and durability tend to decrease. If the ratio of (ii) to (i) is too low, moisture and heat resistance tends to decrease.

[0125] [Activated energy ray curable compound (E)] In this release adhesive composition, an active energy ray curable compound (E) may be used as needed to set the unsaturated group concentration within the desired range.

[0126] Examples of the above-mentioned active energy ray curable compound (E) include urethane (meth)acrylate compounds and ethylenically unsaturated monomers having an ethylenically unsaturated group.

[0127] The above-mentioned urethane (meth)acrylate compounds are (meth)acrylate compounds having a urethane bond in the molecule, and can be produced by reacting a hydroxyl group-containing (meth)acrylic compound with a polyvalent isocyanate compound, and further, if necessary, a polyol. Furthermore, intentionally retaining isocyanate groups to create urethane (meth)acrylate compounds with isocyanate groups and unsaturated bonds in the molecule, and creating crosslinking points with polyester resin (A) to form a release adhesive, is also effective in reducing the tackiness after energy transfer by incorporating reaction sites within the main component.

[0128] Examples of the above hydroxyl group-containing (meth)acrylic compounds include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalate, 2-hydroxy-3-(meth)acryloyloxypropyl (meth)acrylate, caprolactone-modified 2-hydroxyethyl (meth)acrylate, Examples include pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, caprolactone-modified dipentaerythritol penta(meth)acrylate, caprolactone-modified pentaerythritol tri(meth)acrylate, ethylene oxide-modified dipentaerythritol penta(meth)acrylate, and ethylene oxide-modified pentaerythritol tri(meth)acrylate. Among these, hydroxyl group-containing (meth)acrylic compounds having three or more acryloyl groups are preferably used. These can be used individually or in combination of two or more.

[0129] The above-mentioned polyvalent isocyanate compounds are not particularly limited and include, for example, aromatic, aliphatic, and alicyclic polyisocyanates, among others, tolylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, polyphenylmethane polyisocyanate, modified diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, tetramethylxylylene diisocyanate, isophorone diisocyanate, norbolol. Examples include polyisocyanates such as cellulose diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, phenylenediisocyanate, lysine diisocyanate, lysine triisocyanate, and naphthalene diisocyanate, or trimer compounds or polymer compounds of these polyisocyanates, burette-type polyisocyanates, water-dispersible polyisocyanates (for example, "Aquanate 100", "Aquanate 110", "Aquanate 200", and "Aquanate 210" manufactured by Nippon Polyurethane Industries Co., Ltd.), or reaction products of these polyisocyanates with polyols.

[0130] Such polyols are not particularly limited, but include, for example, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, polybutylene glycol, 1,6-hexanediol, neopentyl glycol, cyclohexanedimethanol, hydrogenated bisphenol A, polycaprolactone, trimethylolethane, trimethylolpropane, polytrimethylolpropane, pentaerythritol, polypentaerythritol, sorbitol, mannitol, glycerin, polyglycerin, Examples include polyhydric alcohols such as polytetramethylene glycol; polyether polyols having at least one structure of polyethylene oxide, polypropylene oxide, or ethylene oxide / propylene oxide block or random copolymerization; polyester polyols which are condensates of the polyhydric alcohol or polyether polyol with polybasic acids such as maleic anhydride, maleic acid, fumaric acid, itaconic anhydride, itaconic acid, adipic acid, and isophthalic acid; caprolactone-modified polyols such as caprolactone-modified polytetramethylene polyol; polyolefin-based polyols; and polybutadiene-based polyols such as hydrogenated polybutadiene polyol.

[0131] Furthermore, examples of such polyols include carboxyl group-containing polyols such as 2,2-bis(hydroxymethyl)butyric acid, tartaric acid, 2,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, 2,2-bis(hydroxymethyl)propionic acid, 2,2-bis(hydroxyethyl)propionic acid, 2,2-bis(hydroxypropyl)propionic acid, dihydroxymethylacetic acid, bis(4-hydroxyphenyl)acetic acid, 4,4-bis(4-hydroxyphenyl)pentanoic acid, and homogentisic acid, as well as sulfonic acid group-containing or sulfonic acid base-containing polyols such as sodium 1,4-butanediolsulfonate.

[0132] When using the reaction product of a polyisocyanate and a polyol, for example, it may be used as a terminal isocyanate group-containing polyisocyanate obtained by reacting the above polyol with the above polyisocyanate. In such a reaction between a polyisocyanate and a polyol, it is also preferable to use a metal catalyst such as dibutyltin dilaurate or an amine catalyst such as 1,8-diazabicyclo[5.4.0]undecene-7 to promote the reaction.

[0133] The method for producing the above-mentioned urethane (meth)acrylate compounds is not particularly limited. For example, a method can be used in which a hydroxyl group-containing (meth)acrylic compound and a polyvalent isocyanate compound are mixed in an inert gas atmosphere and reacted at 30 to 80°C for 2 to 10 hours. In this reaction, it is preferable to use a urethane catalyst such as tin octenoate, di-n-butyltin dilaurate, lead octyolate, potassium octyolate, potassium acetate, stanus octoate, or triethylenediamine.

[0134] The weight-average molecular weight of the urethane (meth)acrylate compound is preferably 300 to 4000, more preferably 1000 to 3500, and particularly preferably 1200 to 3000. The method for measuring the weight-average molecular weight is the same as described above.

[0135] Examples of ethylenically unsaturated monomers having an ethylenically unsaturated group include monofunctional monomers having one ethylenically unsaturated group in one molecule, difunctional monomers having two ethylenically unsaturated groups in one molecule, and trifunctional or higher monomers having three or more ethylenically unsaturated groups in one molecule.

[0136] Examples of the above monofunctional monomers include styrene, vinyltoluene, chlorostyrene, α-methylstyrene, methyl (meth)acrylate, ethyl (meth)acrylate, acrylonitrile, vinyl acetate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, phenoxyethyl (meth)acrylate, 2-phenoxy-2-hydroxypropyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, glycerin mono (meth)acrylate, glycidyl (meth)acrylate, lauryl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, tricyclodecanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, n-butyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate. Phthalate derivatives such as acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, dodecyl (meth)acrylate, n-stearyl (meth)acrylate, benzyl (meth)acrylate, phenolethylene oxide modified (meth)acrylate, nonylphenol propylene oxide modified (meth)acrylate, 2-(meth)acryloyloxy-2-hydroxypropyl phthalate, etc. Examples include half-esters (meth)acrylates, furfuryl (meth)acrylate, carbitol (meth)acrylate, benzyl (meth)acrylate, butoxyethyl (meth)acrylate, allyl (meth)acrylate, acryloylmorpholine, 2-hydroxyethyl acrylamide, N-methylol (meth)acrylamide, N-vinylpyrrolidone, 2-vinylpyridine, and 2-(meth)acryloyloxyethyl acid phosphate monoesters.

[0137] Examples of the above-mentioned bifunctional monomers include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethylene oxide-modified bisphenol A type di(meth)acrylate, propylene oxide-modified bisphenol A type di(meth)acrylate, 1 Examples include 6-hexanediol di(meth)acrylate, 1,6-hexanediol ethylene oxide-modified di(meth)acrylate, glycerin di(meth)acrylate, pentaerythritol di(meth)acrylate, ethylene glycol diglycidyl ether di(meth)acrylate, diethylene glycol diglycidyl ether di(meth)acrylate, diglycidyl phthalate diglycidyl ester di(meth)acrylate, hydroxypivalic acid-modified neopentyl glycol di(meth)acrylate, isocyanurate ethylene oxide-modified diacrylate, and 2-(meth)acryloyloxyethyl acid phosphate diester.

[0138] Examples of monomers with three or more functionalities include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tri(meth)acryloyloxyethoxytrimethylolpropane, and glycerin poly Examples include glycidyl ether poly(meth)acrylate, isocyanurate ethylene oxide-modified tri(meth)acrylate, ethylene oxide-modified dipentaerythritol penta(meth)acrylate, ethylene oxide-modified dipentaerythritol hexa(meth)acrylate, ethylene oxide-modified pentaerythritol tri(meth)acrylate, ethylene oxide-modified pentaerythritol tetra(meth)acrylate, succinate-modified pentaerythritol tri(meth)acrylate, etc.

[0139] In addition to the above, other ethylenically unsaturated monomers include Michael adducts of acrylic acid and 2-acryloyloxyethyl dicarboxylic acid monoesters. Examples of Michael adducts of acrylic acid include acrylic acid dimers, methacrylate dimers, acrylic acid trimers, methacrylate trimers, acrylic acid tetramers, and methacrylate tetramers. Examples of 2-acryloyloxyethyl dicarboxylic acid monoesters, which are carboxylic acids with specific substituents, include 2-acryloyloxyethyl succinate monoester, 2-methacryloyloxyethyl succinate monoester, 2-acryloyloxyethyl phthalate monoester, 2-methacryloyloxyethyl phthalate monoester, 2-acryloyloxyethyl hexahydrophthalate monoester, and 2-methacryloyloxyethyl hexahydrophthalate monoester. Furthermore, oligoester acrylates can also be mentioned.

[0140] These active energy ray curable compounds (E), such as urethane (meth)acrylate compounds and ethylenically unsaturated monomers, may be used individually or in combination of two or more. In particular, to increase the crosslinking density when used as a release adhesive, it is preferable to use polyfunctional urethane (meth)acrylate compounds or polyfunctional ethylenically unsaturated monomers, and especially preferable to use compounds having three or more unsaturated groups. Furthermore, to improve adhesion to the substrate or adherend, it is also preferable to use highly polar urethane (meth)acrylate compounds or ethylenically unsaturated monomers with polar moieties.

[0141] The content of the active energy ray curable compound (E) is preferably 1 to 50 parts by weight, more preferably 2 to 20 parts by weight, and even more preferably 3 to 10 parts by weight, per 100 parts by weight of the polyester resin (A). If the content is too high, the cohesive force of the adhesive layer after energy application tends to become too high, resulting in low elongation, while if it is too low, the adhesive force after energy application tends not to decrease easily.

[0142] [Polymerization inhibitors] In this release adhesive composition, polymerization inhibitors may be used as needed. This is preferable in terms of improving the stability of the adhesive sheet and enabling it to withstand use in harsh conditions, such as heat-resistant applications, followed by a peeling process.

[0143] The content of such additional polymerization inhibitor is not limited, but is usually 20 ppm to 10,000 ppm, and more preferably 50 ppm to 1,000 ppm, relative to the entire release adhesive composition.

[0144] Furthermore, while there are no particular limitations on the polymerization inhibitor, it is preferable to use a phenol-type inhibitor, and it is preferable to use methoxyhydroquinone, hydroquinone, diter-butylhydroxytoluene, etc. Furthermore, it is also preferable to use a hindered phenol polymerization inhibitor as the phenol-type inhibitor. Examples of hindered phenol polymerization inhibitors include polymerization inhibitors having a hindered phenol structure in which a sterically hindered group such as a tert-butyl group is bonded to at least one carbon atom adjacent to the carbon atom on the aromatic ring to which the hydroxyl group of phenol is bonded.

[0145] [Other ingredients] The release adhesive composition may further contain other components, such as antistatic agents, antioxidants, plasticizers, fillers, pigments, diluents, anti-aging agents, UV absorbers, UV stabilizers, and tackifying resins, to the extent that they do not impair the effects of the present invention. These additives can be used individually or in combination of two or more. In addition to the other components mentioned above, the release adhesive composition may also contain small amounts of impurities contained in the raw materials used to manufacture the components of the release adhesive composition.

[0146] This release adhesive composition is obtained by mixing the above-mentioned polyester resin (A), preferably a crosslinking agent (B), a polymerization initiator (C), and optionally a hydrolysis inhibitor (D), an active energy ray curable compound (E), a polymerization inhibitor, and other components.

[0147] The polyester resin (A) is preferably the main component of this release adhesive composition. Here, the main component is defined as having a content of 50% by weight or more of the entire release adhesive composition, preferably 60 to 99.9% by weight, more preferably 70 to 99.7% by weight, particularly preferably 80 to 99.5% by weight, and especially preferably 90 to 99% by weight. The crosslinking agent (B) content is 0.1 to 20% by weight of the total release adhesive composition, preferably 0.2 to 15% by weight, and more preferably 0.5 to 10% by weight. The content of polymerization initiator (C) is 0.01 to 10% by weight of the total release adhesive composition, preferably 0.1 to 5% by weight, and more preferably 0.2 to 3% by weight. The content of the hydrolysis inhibitor (D) is 0.01 to 10% by weight of the total release adhesive composition, preferably 0.1 to 5% by weight, and more preferably 0.3 to 3% by weight. The content of the active energy ray curable compound (E) is 1 to 33% by weight of the total release adhesive composition, preferably 2 to 20% by weight, and more preferably 3 to 10% by weight.

[0148] A peelable adhesive composition obtained by crosslinking this peelable adhesive composition is a peelable adhesive according to one aspect of the present invention (hereinafter referred to as "this peelable adhesive"). When energy is applied to this peelable adhesive, the unsaturated groups of this peelable adhesive polymerize, causing the peelable adhesive to harden and resulting in a decrease in adhesive strength, thereby exhibiting peelability.

[0149] <Releasable adhesive> This release adhesive is suitably used as the adhesive layer of a release adhesive sheet, and it is preferable that the release adhesive sheet has a release adhesive layer containing this release adhesive on one or both sides of the support substrate. Furthermore, it is also preferable to use a substrate-less double-sided adhesive sheet without a support substrate, as it offers excellent transparency and high adhesive strength relative to its thickness. The release adhesive sheet will be described below.

[0150] In this invention, the term "sheet" is used to include "film" and "tape" as well.

[0151] <Removable adhesive sheet> A peelable adhesive sheet (hereinafter referred to as "this peelable adhesive sheet") which is one embodiment of the present invention, can be manufactured according to a known general method for manufacturing peelable adhesive sheets, for example, as follows. The release adhesive composition is applied directly to the release-treated surface of a release film or to a base sheet, either as is or after adjusting its concentration with a suitable organic solvent. Then, it is dried by, for example, heat treatment at 80-130°C for 0.5-10 minutes, and this is then applied to the base sheet or release film to obtain the release adhesive sheet. Furthermore, it is preferable to perform further aging after drying to balance the adhesive properties.

[0152] Examples of the above-mentioned base sheets include polyester resins such as polyethylene naphthalate, polyethylene terephthalate, polybutylene terephthalate, and polyethylene terephthalate / isophthalate copolymers; polyolefin resins such as polyethylene, polypropylene, and polymethylpentene; polyfluoroethylene resins such as polyvinyl fluoride, polyvinylidene fluoride, and polyfluoroethylene; polyamides such as nylon 6 and nylon 6,6; vinyl polymers such as polyvinyl chloride, polyvinyl chloride / vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polyvinyl alcohol, and vinylon; cellulose resins such as cellulose triacetate and cellophane; acrylic resins such as polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate, and polybutyl acrylate; synthetic resin sheets such as polystyrene, polycarbonate, polyarylate, and polyimide; and woven or nonwoven fabrics made of metal foils of aluminum, copper, and iron, paper such as fine paper and glassine paper, glass fibers, natural fibers, and synthetic fibers. These base sheets can be used as single layers or as multi-layered structures made by laminating two or more types. Among these, synthetic resin sheets are preferred from the viewpoint of weight reduction, and polyester resins and polyolefin resins are particularly preferred.

[0153] Furthermore, as the release film, for example, various synthetic resin sheets, paper, textiles, nonwoven fabrics, etc., as exemplified in the base sheet, can be used, which have been treated with a release agent.

[0154] Furthermore, the coating method for the above-mentioned release adhesive composition is not particularly limited as long as it is a general coating method, and examples include roll coating, die coating, gravure coating, comma coating, and screen printing.

[0155] Furthermore, when forming a thick adhesive layer, a releaseable adhesive composition whose viscosity has been adjusted by the method described above can be directly applied to the peeled surface of the release film, dried to produce two or more release films with adhesive layers, and the adhesive layers of the two release films with adhesive layers can be bonded together to form a thick adhesive layer.

[0156] The thickness of the adhesive layer of the above-mentioned peelable adhesive sheet is usually preferably 10 to 200 μm, and more preferably 15 to 100 μm.

[0157] To further enhance the ability to follow uneven surfaces and improve stretchability, a soft intermediate layer can be inserted between the base layer and the adhesive layer of this release-type adhesive sheet, if necessary.

[0158] The thickness of the adhesive layer is determined by subtracting the measured thickness of the components other than the adhesive layer from the measured thickness of the entire release adhesive sheet using Mitutoyo's "ID-C112B".

[0159] The aging conditions described above typically involve a temperature of room temperature (23°C) to 70°C, and a duration of 1 to 30 days. Specifically, this can be done under conditions such as 1 to 20 days at 23°C, 3 to 10 days at 23°C, or 1 to 10 days at 40°C.

[0160] The gel fraction of the adhesive layer of this release-type adhesive sheet before energy application is preferably 20% or more, particularly preferably 30-90%, and even more preferably 40-70%, from the viewpoint of durability and adhesive strength. If the gel fraction is too low, the cohesive force decreases, which tends to reduce durability. Conversely, if the gel fraction is too high, there is a concern that the adhesive strength will decrease due to an increase in cohesive force.

[0161] Furthermore, the gel fraction of the adhesive layer of this release-type adhesive sheet after energy application is preferably 70% or more, particularly preferably 80% or more, and even more preferably 90% or more, from the viewpoint of adhesive strength. If the gel fraction is too low, the cohesive force decreases, which increases the adhesive strength and tends to result in poor release properties. The upper limit of the gel fraction is usually 100%.

[0162] The gel fraction mentioned above is an indicator of the degree of crosslinking and can be calculated, for example, by the following method: A release adhesive sheet (without a separator), which consists of a polymer sheet (e.g., polyethylene terephthalate film) as the base material with a release adhesive layer formed on it, is wrapped in a 200-mesh stainless steel wire mesh and immersed in toluene at 23°C for 24 hours. The weight percentage of the insoluble adhesive component remaining in the wire mesh is taken as the gel fraction. However, the weight of the base material is subtracted.

[0163] The resulting release adhesive sheet exhibits high adhesive strength when applied to a substrate, protecting the substrate surface. By applying energy after the processing step, the ethylenically unsaturated groups contained in the release adhesive layer polymerize, hardening the release adhesive layer and reducing its adhesive strength. This allows for easy removal, and less adhesive residue is left behind when peeled from the substrate.

[0164] The above-mentioned energies can include far-ultraviolet, ultraviolet, near-ultraviolet, and infrared rays, as well as electromagnetic waves such as X-rays and gamma rays, and electron beams, proton beams, and neutron beams. However, curing by ultraviolet irradiation is advantageous in terms of curing speed, availability of irradiation equipment, and cost. When using electron beam irradiation, curing is possible even without using the above-mentioned photopolymerization initiator (C1).

[0165] Light sources used for the above-mentioned ultraviolet irradiation include high-pressure mercury lamps, electrodeless lamps, ultra-high-pressure mercury lamps, carbon arc lamps, xenon lamps, metal halide lamps, chemical lamps, black lights, and LED lamps. In the case of high-pressure mercury lamps, for example, 5 to 3000 mJ / cm² can be used. 2Preferably 50-2000 mJ / cm² 2 This is performed under the following conditions. Furthermore, in the case of the electrodeless lamp mentioned above, for example, 2 to 2000 mJ / cm². 2 Preferably 10 to 1000 mJ / cm² 2 The procedure is carried out under these conditions. The irradiation time varies depending on the type of light source, the distance between the light source and the coated surface, the coating thickness, and other conditions, but it is usually several seconds to tens of seconds, and in some cases even a fraction of a second. On the other hand, in the case of electron beam irradiation as described above, it is preferable to use an electron beam with an energy in the range of 50 to 1000 kev and an irradiation dose of 2 to 50 Mrad.

[0166] The adhesive strength (α) of the release adhesive layer of this release adhesive sheet is appropriately determined according to the material of the adherend, but for example, when adhering to semiconductor wafers, glass substrates, polycarbonate plates, polymethyl methacrylate plates, or PET sheets with an ITO layer deposited on them, the adhesive strength immediately after application is preferably 1 to 500 N / 25 mm, and particularly preferably 2 to 100 N / 25 mm.

[0167] The above adhesive strength (α) can be measured, for example, as follows. The release adhesive sheet is attached to the SUS-BA plate of the adherend and left to stand at 23°C and 50%RH for at least 30 minutes. Then, the 180-degree peel strength (N / 25mm) is measured in accordance with JIS Z0237.

[0168] Furthermore, the adhesive strength (β) of the release adhesive layer of this release adhesive sheet after energy application is preferably 2N / 25mm or less, more preferably 1.5N / 25mm or less, particularly preferably 1N / 25mm or less, and even more preferably 0.5N / 25mm or less. If the adhesive strength (β) is too high compared to the above range, the re-peelability tends to be poor, making it difficult to peel off and leaving adhesive residue. The lower limit of the adhesive strength (β) is better the lower it is, but in practice it is usually 0.0001N / 25mm, preferably 0.001N / 25mm, and particularly preferably 0.01N / 25mm.

[0169] The above adhesive strength (β) can be measured, for example, as follows. This release adhesive sheet is attached to the SUS-BA plate of the substrate and left to stand at 23°C and 50%RH for at least 30 minutes, after which it is subjected to ultraviolet irradiation (500 mJ / cm² using a high-pressure mercury lamp). 2 After performing the following steps, the 180-degree peel strength (N / 25mm) is measured in accordance with JIS Z0237.

[0170] Furthermore, the adhesive strength after energy application is preferably 1 / 3 or less of the adhesive strength before energy application, and more preferably 1 / 10 or less.

[0171] The elongation at break of the adhesive layer after energy application is preferably 50% or more, more preferably 70% to 5000%, particularly preferably 80% to 1000%, and most preferably 100% to 500%. If the elongation is insufficient, the adhesive tends to break when peeling off the release adhesive, causing adhesive residue. While excessive elongation does not have much adverse effect, it tends to cause adhesive residue due to a loosening of the crosslinking network.

[0172] The fracture stress of the above adhesive layer after energy application is 0.5 N / mm 2 Preferably, it is above 0.7 N / mm², and more preferably 0.7 N / mm². 2 The above is particularly preferably 1.0 N / mm 2 In summary, the most preferred value is 1.2 N / mm². 2 That concludes the explanation. When the breaking stress is low, the release adhesive tends to break when peeled off, leading to adhesive residue. The upper limit of the breaking stress is effectively 100 N / mm². 2 That is the case.

[0173] The above-mentioned fracture elongation and fracture stress can be measured, for example, as follows. This release adhesive sheet was made using double-sided release film, left to stand at 23°C and 50% RH for at least 30 minutes, and then irradiated with ultraviolet light (500 mJ / cm² using a high-pressure mercury lamp). 2The release films on both sides are peeled off, and the elongation and strength at the breaking point are measured at a temperature of 23°C and a humidity of 50%, in accordance with JIS K 7127, at a tensile speed of 10 mm / min.

[0174] This peelable adhesive sheet has excellent adhesion to the adherend, and when peeled off, it can be smoothly removed from the adherend without leaving any adhesive residue by irradiating it with active energy rays. For example, it can be used as a temporary surface protection adhesive sheet to temporarily protect the surface of circuit boards such as semiconductor wafers and FPC substrates or ITO transparent electrode layers, or as a temporary fixing adhesive sheet to temporarily hold and reinforce products during the manufacturing process. [Examples]

[0175] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the invention. In the examples, "parts" and "%" refer to weight-based amounts.

[0176] [Manufacturing of polyester resin (A-1)] In a reaction vessel equipped with a heating device, thermometer, stirrer, rectification column, nitrogen inlet tube, and vacuum device, 9.6 parts (0.2 moles) of isophthalic acid and 46.8 parts (0.8 moles) of sebacic acid as polycarboxylic acids, 27.1 parts (0.9 moles) of neopentyl glycol, 13.0 parts (0.5 moles) of 1,4-butanediol, 3.0 parts (0.087 moles) of 1,6-hexanediol, and 0.5 parts (0.013 moles) of trimethylolpropane as polyhydric alcohols, and 0.01 part of tetrabutyl titanate as a catalyst were charged. The internal temperature was gradually increased to 250°C, and the esterification reaction was carried out over 4 hours. Subsequently, the internal temperature was increased to 260°C, 0.01 part of tetrabutyl titanate as a catalyst was charged, the pressure was reduced to 1.33 hPa, and the polymerization reaction was carried out over 3 hours to produce polyester resin (A-1). The resin composition (molar ratio) of the obtained polyester resin (A-1) was isophthalic acid / sebacic acid / neopentyl glycol / 1,4-butanediol / 1,6-hexanediol / trimethylolpropane = 0.2 / 0.8 / 0.59 / 0.34 / 0.06 / 0.01. The ester group concentration was 7.7 mmol / g, the heat of fusion was 0 J / g, the weight-average molecular weight was 81000, the glass transition temperature (Tg) was -49°C, and the acid value was 0.02 mg KOH / g.

[0177] [Manufacturing of polyester resin (A-2)] In a reaction vessel equipped with a heating device, thermometer, stirrer, rectification column, nitrogen inlet tube, and vacuum device, 9.6 parts (0.2 moles) of isophthalic acid and 46.8 parts (0.8 moles) of sebacic acid as polycarboxylic acids, 27.1 parts (0.9 moles) of neopentyl glycol, 13.0 parts (0.5 moles) of 1,4-butanediol, 3.0 parts (0.087 moles) of 1,6-hexanediol, and 0.5 parts (0.013 moles) of trimethylolpropane as polyhydric alcohols, and 0.01 part of tetrabutyl titanate as a catalyst were charged, and the temperature was gradually raised to an internal temperature of 250°C, and the esterification reaction was carried out over 4 hours. Subsequently, the internal temperature was raised to 260°C, 0.01 parts of tetrabutyl titanate were added as a catalyst, the pressure was reduced to 1.33 hPa, and the polymerization reaction was carried out for 3 hours. Then, the pressure was returned to atmospheric pressure, 0.75 parts of trimethylolpropane were added, and the reaction was carried out at 240°C for 3 hours to produce polyester resin (A-2). The resin composition (molar ratio) of the obtained polyester resin (A-2) was isophthalic acid / sebacic acid / neopentyl glycol / 1,4-butanediol / 1,6-hexanediol / trimethylolpropane = 0.2 / 0.8 / 0.59 / 0.34 / 0.06 / 0.03. The ester group concentration was 7.7 mmol / g, the heat of fusion was 0 J / g, the weight-average molecular weight was 49000, the glass transition temperature (Tg) was -49°C, and the acid value was 0.02 mg KOH / g.

[0178] [Production of unsaturated group-containing polyester resin (A1-1)] The polyester resin (A-2) produced above was diluted with toluene to a solid content of 70%. For every 100 parts of the solid content of the polyester resin (A-2), 4.9 parts of methachloroyloxyethyl isocyanate and 0.05 parts of ZC-150 (urethane catalyst manufactured by Matsumoto Fine Chemical Co., Ltd.) were added, and the reaction was carried out at 50°C for 48 hours to produce an unsaturated group-containing polyester resin (A1-1). The obtained unsaturated group-containing polyester resin (A1-1) was analyzed using an infrared spectrophotometer to confirm the absence of residual isocyanate groups.

[0179] [Manufacturing of unsaturated group-containing polyester resins (A1-2), (A1-3)] The unsaturated group-containing polyester resin (A1-1) described above was manufactured with the polymer composition shown in Table 1.

[0180] The polymer composition ratios of the polyester resins (A-1), (A-2), and unsaturated group-containing polyester resins (A1-1) to (A1-3) are shown in Table 1 below.

[0181] [Manufacturing of acrylic resin (Z-1)] The monomers shown in Table 2 below were prepared and polymerized by conventional methods to produce an acrylic resin (Z-1).

[0182] [Table 1]

[0183] [Table 2]

[0184] The measurement methods for each physical property are as follows:

[0185] <Glass transition temperature (Tg)> The test specimen was heated and cooled at a rate of 10°C / min from room temperature, and the amount of heat released was measured using a differential scanning calorimeter. Two extension lines were drawn to the endothermic or exothermic curve, and the temperature at the intersection of the 1 / 2 line between the extension lines and the endothermic or exothermic curve was defined as the glass transition temperature.

[0186] <Weight-average molecular weight, number-average molecular weight, and peak-top molecular weight> Weight-average molecular weight and number-average molecular weight are average molecular weights converted to standard polystyrene molecular weight. The analysis was performed using a high-performance liquid chromatograph (Waters Japan, "Waters 2695 (separation module)" and "Waters 2414 (detector)") with a Shodex GPC KF-806L column (exclusion limit molecular weight: 2 × 10⁶). 7 Separation range: 100~2×10 7 The measurement was performed using three tubes connected in series, each with a theoretical plate count of 10,000 stages / tube, a filler material of styrene-divinylbenzene copolymer, and a filler particle size of 10 μm.

[0187] <Acid value, hydroxyl value> The acid value and hydroxyl value were determined by neutralization titration in accordance with JIS K0070.

[0188] Prior to the examples, the following components were prepared.

[0189] [Crosslinking agent (B)] • Isocyanate-based crosslinking agent (B-1): "PR-9000" (manufactured by BASF) (crosslinking agent containing unsaturated groups) • Isocyanate-based crosslinking agent (B-2): "Coronate L55E" (manufactured by Tosoh Corporation)

[0190] [Polymerization initiator (C)] • Photopolymerization initiator (C-1): "Omnirad 184" (manufactured by BASF) [Hydrolysis inhibitor (D)] • Carbodiimide compound (D-1): "Carbodilite V-09GB" (manufactured by Nisshinbo Chemical Co., Ltd.) [Urethane catalyst] • Zirconium-based compound: "Orgatics ZC-2010" (manufactured by Matsumoto Fine Chemical Co., Ltd.) (diluted with acetylacetone to a solid content of 1%) [Antioxidant] • Hindered phenol antioxidant: "IRGANOX1010" (manufactured by BASF)

[0191] [Production of Activated Energy Ray Curable Compound (E-1)] In a four-necked round-bottom flask equipped with a reflux condenser, stirrer, nitrogen gas inlet, and thermometer, 6.6 parts of isophorone diisocyanate (IPDI), 93.4 parts of dipentaerythritol pentaacrylate, 0.03 parts of di-t-butylhydroxyphenol, and 0.02 parts of dibutyltin dilaurate were charged, and the reaction was continued at 50°C to obtain an active energy ray-curable compound (E-1). The weight-average molecular weight of the active energy ray-curable compound (E-1) was 1500.

[0192] <Examples 1-6, Comparative Examples 1-3> Each component was blended as shown in Table 3 below, and diluted with ethyl acetate and / or toluene to a viscosity (1000-5000 mPa·s / 25℃) suitable for coating, to prepare a release adhesive composition. Using this release adhesive composition, a release adhesive sheet was prepared by the following method.

[0193] [Table 3]

[0194] [Preparation of release adhesive sheets] A polyethylene terephthalate (PET) film (38 μm thick) was prepared as a base material. Under conditions where ultraviolet light was blocked, the above-mentioned release adhesive composition was applied to the surface of the PET film so that its thickness after drying was 25 μm, and then dried at 100°C for 2 minutes. After that, a release-treated PET film was attached to the surface of the adhesive layer for protection to obtain a release adhesive sheet.

[0195] The peelable adhesive sheets of the examples and comparative examples obtained in this manner were cured at 40°C for 4 days, and then their various physical properties were evaluated according to the method described below. The results are shown in Table 4 below. The PET sheets that had been treated for release were removed when conducting various measurement tests.

[0196] <Gel fraction> The release adhesive sheet obtained above was wrapped in a 200-mesh stainless steel wire mesh and immersed in toluene at 23°C for 24 hours. The weight percentage of the insoluble release adhesive component remaining in the wire mesh was defined as the gel fraction. The gel fraction was similarly measured after ultraviolet irradiation. However, the weight of the substrate was subtracted.

[0197] <Adhesion strength before UV irradiation> The peelable adhesive sheet obtained above was attached to the SUS-BA plate of the adherend and left to stand at 23°C and 50%RH for 30 minutes or more. Then, the 180-degree peel strength (N / 25mm) was measured in accordance with JIS Z0237.

[0198] <40℃ holding power> The peelable adhesive sheets obtained above were applied to SUS304 as the substrate in accordance with JIS Z-0237, covering an area of ​​25 mm x 25 mm. After being left standing at 40°C for 20 minutes, a 1 kg load was applied, and the time until they fell, or the condition after 24 hours if they did not fall, was visually inspected and evaluated according to the following criteria. (Evaluation Criteria) ○...It did not fall even after being left undisturbed for 24 hours. ×...It fell while left undisturbed for 24 hours.

[0199] <Adhesive strength after UV irradiation> The peelable adhesive sheet obtained above was attached to the SUS304-BA plate of the substrate and left to stand at 23°C and 50%RH for at least 30 minutes, after which it was subjected to ultraviolet irradiation (500 mJ / cm² using a high-pressure mercury lamp). 2 After performing the following steps, the 180-degree peel strength (N / 25mm) was measured in accordance with JIS Z0237.

[0200] [Preparation of a double-sided release adhesive sheet with PET backing] A release-treated polyethylene terephthalate (PET) film (38 μm thick) was prepared. With ultraviolet light blocked, the release-treated surface of the PET film was coated with the release-treated adhesive composition to a dry thickness of 50 μm, and then dried at 100°C for 5 minutes. After that, a release-treated PET film was attached to the surface of the adhesive layer for protection, and cured at 40°C for 7 days to obtain a release-type adhesive sheet with a double-sided release PET backing.

[0201] The above-mentioned double-sided release adhesive sheet with PET backing was exposed to ultraviolet light with a wavelength of 365 nm at an irradiation intensity of 200 mW / cm². 2 , cumulative light intensity 500 mJ / cm 2 The sheet was irradiated and cured under conditions that resulted in the desired outcome. After curing, the double-sided release PET-backed release adhesive sheet was punched out with a dumbbell to create strip-shaped samples measuring 15 mm in width and 75 mm in length. The release PET on both sides was then peeled off, and these were used as sample pieces for measurement.

[0202] <Elongation at break after UV irradiation (%)> The sample pieces obtained above were subjected to tensile testing in accordance with JIS K 7127 using a tensile testing machine "AG-X" (manufactured by Shimadzu Corporation) at a temperature of 23°C and 50% humidity. The tensile speed was 10 mm / min, and the elongation at the breaking point was measured.

[0203] <Breakdown stress after UV irradiation (N / mm 2 )> The sample pieces obtained above were subjected to tensile testing in accordance with JIS K 7127 using a tensile testing machine "AG-X" (manufactured by Shimadzu Corporation) at a temperature of 23°C and 50% humidity. The tensile speed was 10 mm / min, and the strength at the fracture point was measured.

[0204] [Table 4]

[0205] The peelable adhesive sheets of Examples 1 to 6, prepared from the peelable adhesive composition of the present invention, exhibited excellent peelability and high elongation because the adhesive force after energy application was a peelable adhesive force (low adhesive force). In other words, it is thought that the amount of adhesive residue would be reduced. On the other hand, the release adhesive sheet made from the release adhesive composition of Comparative Example 1, which had a high concentration of unsaturated groups, exhibited excessively high cohesive force after UV irradiation, resulting in low elongation at break. In other words, it is expected that the adhesive layer will be prone to rupture, leading to a large amount of adhesive residue. Furthermore, the peelable adhesive sheet made from the peelable adhesive composition of Comparative Example 2, which does not contain unsaturated groups, had high adhesive strength even after energy was applied, making it difficult to peel off. Furthermore, the peelable adhesive sheet of Comparative Example 3, which uses an acrylic resin, is expected to have a low elongation at break and a large amount of adhesive residue because it uses an acrylic resin (presumably because the molecular weight between crosslinking points is low due to the arrangement of unsaturated groups in the resin side chains). [Industrial applicability]

[0206] This release adhesive composition exhibits sufficient adhesive strength to be used as an adhesive before energy is applied, and becomes extremely low adhesive strength after energy is applied. Therefore, it can fix the adherend when applied before energy is applied, and can be easily peeled off after energy is applied. Furthermore, even when cured by energy application, this release adhesive composition has the characteristic of high elongation, making it difficult to tear and leaving little adhesive residue, even when used on uneven surfaces such as bumps where the adhesive layer might physically catch. Therefore, it is preferable as an adhesive layer for an adhesive sheet used to temporarily protect the surface when processing workpieces such as electronic substrates, semiconductor wafers, glass products, metal plates, and plastic plates. More specifically, it can be used very effectively as an adhesive layer to temporarily protect the circuit pattern formation surface of a semiconductor wafer having bumps or other irregularities on the adherend.

Claims

1. A release adhesive composition comprising a polyester resin (A) and a crosslinking agent (B), characterized in that the unsaturated group concentration is 0.01 to 1.5 mmol / g, and the unsaturated group is a (meth)acryloyl group.

2. A release adhesive composition for semiconductor processing sheets comprising a polyester resin (A) and a crosslinking agent (B), characterized in that the unsaturated group concentration is 0.01 to 1.5 mmol / g, and the unsaturated group is a (meth)acryloyl group.

3. The release adhesive composition according to claim 1 or 2, characterized in that the unsaturated group concentration is 0.01 to 1.0 mmol / g.

4. The release adhesive composition according to claim 1 or 2, characterized in that the content of the polyester resin (A) is 50% by weight or more of the total release adhesive composition.

5. The release adhesive composition according to claim 1 or 2, characterized in that the polyester resin (A) is an unsaturated group-containing polyester resin (A1).

6. The release adhesive composition according to claim 1 or 2, characterized in that the crosslinking agent (B) has functional groups and unsaturated groups that react with the polyester resin (A).

7. Furthermore, the release adhesive composition according to claim 1 or 2 is characterized by containing a polymerization initiator (C).

8. A release adhesive characterized by using the release adhesive composition described in claim 1 or 2.

9. A peelable adhesive sheet characterized by comprising a base material and an adhesive layer containing the peelable adhesive described in claim 8.

10. The peelable adhesive sheet according to claim 9, characterized in that the adhesive strength (β) of the peelable adhesive sheet is 2 N / 25 mm or less. Adhesive strength (β): The release adhesive sheet is attached to the SUS-BA plate, the substrate, and left to stand at 23°C and 50% RH for at least 30 minutes, followed by UV irradiation (500 mJ / cm² using a high-pressure mercury lamp). 2 After performing the following steps, the 180-degree peel strength (N / 25mm) was measured in accordance with JIS Z0237.

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