JP2019131638A - Adhesive composition, adhesive sheet, and manufacturing method of adhesive - Google Patents

Abstract

To provide an adhesive composition capable of forming an adhesive of which adhesive force is effectively reduced by irradiation of an active energy ray.SOLUTION: There is provided an adhesive composition forming an adhesive of which adhesive force is reduced by irradiation of an active energy ray, containing an acrylic polymer (A) having an active hydrogen group, a compound (B) having a carbon-carbon double bond and a functional group reacting with the active hydrogen group, adding the carbon-carbon double bond to the acrylic polymer (A) contributing to formation of the adhesive, and having mass change rate when heated at 90°C for 5 min. of 5% or less, and a crosslinking agent (C) having 2 or more functional groups reacting with the active hydrogen group. Equivalence of the carbon-carbon double bond obtained by the compound (B) based on the acrylic polymer (A) is 1.9 meq/g or more, or content of the compound (B) is 30 to 150 pts.mass based on 100 pts.mass of the acrylic polymer (A).SELECTED DRAWING: None

Description

  The present invention relates to a pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet, and a method for producing a pressure-sensitive adhesive.

  The pressure-sensitive adhesive sheet is used for various purposes such as fixing, bonding, protection, decoration, and conveyance of articles. A typical example of the pressure-sensitive adhesive sheet includes a pressure-sensitive adhesive (pressure-sensitive adhesive layer) formed of a pressure-sensitive adhesive composition having an acrylic polymer as a base polymer. In a pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer formed of a pressure-sensitive adhesive composition containing an acrylic polymer, a pressure-sensitive adhesive sheet is also known in which the pressure-sensitive adhesive strength of the pressure-sensitive adhesive layer is reduced by irradiation with active energy rays such as ultraviolet rays and electron beams. ing.

  An adhesive sheet in which the adhesive strength of the adhesive layer is reduced by irradiation with an active energy ray is used in the IC chip manufacturing industry as, for example, a dicing tape or a UV tape. Taking IC chip production as an example, when dicing a semiconductor wafer that has been affixed to an adhesive sheet and fixed in advance along the chip shape, the adhesive layer fixes the semiconductor wafer and the divided chips. It is required to have sufficient adhesive strength. At the same time, when the divided chip is peeled off from the pressure-sensitive adhesive sheet and mounted on a substrate or the like, the pressure-sensitive adhesive layer has the property that the adhesive force is reduced by irradiation with active energy rays and the chip can be easily peeled off. Is required.

  For example, Patent Document 1 discloses an acrylic polymer having a photoactive functional group in an amount of 0.01 to 1.0 meq / g on one surface of a base material that is transparent to ultraviolet rays, A photosensitive adhesive tape formed by applying a photosensitive adhesive composition comprising a crosslinking agent and a photopolymerization initiator is disclosed. Moreover, for example, in Patent Document 2, in a pressure-sensitive adhesive sheet for processing a semiconductor wafer provided with a pressure-sensitive adhesive layer that is cured by radiation and has a reduced adhesive strength, the pressure-sensitive adhesive composition that forms the pressure-sensitive adhesive layer has a carbon-carbon double bond. It is disclosed that a polymer having a side chain as a main component.

JP 2001-139905 A JP 2001-200215 A

  In the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer of the light-sensitive pressure-sensitive adhesive tape disclosed in Patent Document 1 described above, a photoactive functional group (group having a carbon-carbon double bond) is previously added to the acrylic polymer. The polymer which introduce | transduced is used. In addition, the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet disclosed in Patent Document 2 is also subjected to addition reaction of 2-methacryloyloxyethyl isocyanate with an acrylic copolymer in advance to form carbon atoms on the inner chain of the molecule. -Polymers with introduced carbon double bonds are used.

  As described above, conventionally, in order to reduce the adhesive strength of the pressure-sensitive adhesive by irradiation with active energy rays, an acrylic polymer used for the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive is carbon-reacted by irradiation with active energy rays. A carbon double bond is introduced in advance. In this case, in order to sufficiently reduce the adhesive strength of the pressure-sensitive adhesive after irradiation with active energy rays, if a large number of carbon-carbon double bonds are introduced into the acrylic polymer in advance, gelation occurs and coating becomes difficult. It becomes difficult to use as an adhesive composition. Therefore, it is considered that the amount of the carbon-carbon double bond to be introduced into the acrylic polymer in advance needs to be an amount that does not cause gelation.

  On the other hand, depending on the application that uses an adhesive whose adhesive strength is reduced by irradiation with active energy rays, an adhesive that lowers the adhesive strength after irradiation with active energy rays and can be easily peeled off is desired. There is a fact that.

  In view of the above circumstances, the present invention is intended to provide a pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive whose adhesive force is more effectively reduced by irradiation with active energy rays.

  According to the present invention, there is provided a pressure-sensitive adhesive composition that forms a pressure-sensitive adhesive whose adhesive strength is reduced by irradiation with active energy rays, the acrylic polymer (A) having an active hydrogen group, a carbon-carbon double bond, And imparting the carbon-carbon double bond to the acrylic polymer (A) that has a functional group that reacts with the active hydrogen group and contributes to the formation of the pressure-sensitive adhesive, and is heated at 90 ° C. for 5 minutes And a compound (B) having a mass change rate of 5% or less and a cross-linking agent (C) having two or more functional groups that react with the active hydrogen group, with respect to the acrylic polymer (A) A pressure-sensitive adhesive composition in which the equivalent of the carbon-carbon double bond of the compound (B) is 1.9 meq / g or more is provided.

  According to the present invention, there is also provided a pressure-sensitive adhesive composition that forms a pressure-sensitive adhesive whose adhesive strength is reduced by irradiation with active energy rays, the acrylic polymer (A) having an active hydrogen group, and a carbon-carbon double layer. The carbon-carbon double bond is imparted to the acrylic polymer (A) that has a bond and a functional group that reacts with the active hydrogen group and contributes to the formation of the pressure-sensitive adhesive. A compound (B) having a mass change rate of 5% or less when heated for 5 minutes and a crosslinking agent (C) having two or more functional groups that react with the active hydrogen group, The adhesive composition whose content is 30-150 mass parts with respect to 100 mass parts of said acrylic polymers (A) is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the adhesive composition which can form the adhesive which adhesive force falls more effectively by irradiation of an active energy ray can be provided.

  Embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments. In the present disclosure, the phrase “(meth) acryl” means that both “acryl” and “methacryl” are included. Similarly, the term “(meth) acrylate” includes the terms “acrylate” and “methacrylate”.

<Adhesive composition>
The pressure-sensitive adhesive composition of one embodiment of the present invention forms a pressure-sensitive adhesive whose adhesive strength is reduced by irradiation with active energy rays. This pressure-sensitive adhesive composition can form a pressure-sensitive adhesive having an appropriate adhesive strength to the adherend before irradiation with active energy rays, and the adhesive strength decreases after irradiation with active energy rays. A pressure-sensitive adhesive that can be easily peeled off from the adherend can be formed. Specific examples of the active energy rays include α rays, β rays, γ rays, electron beams, neutron rays, X rays, near infrared rays, visible rays, and ultraviolet rays. One or more of them may be used. As the active energy ray, ultraviolet rays are more preferable.

  The pressure-sensitive adhesive composition of one embodiment of the present invention includes an acrylic polymer (A) having an active hydrogen group, a compound (B) having a carbon-carbon double bond and a functional group that reacts with the active hydrogen group. And a crosslinking agent (C) having two or more functional groups that react with the active hydrogen group. The compound (B) used in this pressure-sensitive adhesive composition has a mass change rate of 5% or less when heated at 90 ° C. for 5 minutes. Further, this compound (B) imparts a carbon-carbon double bond to the acrylic polymer (A) that contributes to the formation of the pressure-sensitive adhesive. And in this adhesive composition, the equivalent of the carbon-carbon double bond which the compound (B) has with respect to the acrylic polymer (A) is 1.9 meq / g or more, or the acrylic polymer (A) is 100 parts by mass. The content of the compound (B) with respect to is 30 to 150 parts by mass.

  With the above configuration, the compound (B) can be effectively reacted with the acrylic polymer (A) that contributes to the formation of the pressure-sensitive adhesive when the pressure-sensitive adhesive composition is applied and then dried or cured. -Carbon double bonds can be effectively introduced. Therefore, a pressure-sensitive adhesive containing a polymer having an increased amount of carbon-carbon double bonds can be formed by the pressure-sensitive adhesive composition having the above configuration. When this adhesive is peeled off, the active energy ray can be irradiated to the adhesive. By irradiating the adhesive with active energy rays, a curing reaction can be caused by a carbon-carbon double bond. As a result, the adhesive strength of the adhesive can be effectively reduced, and the adhesive can be easily used. Can be peeled off. Hereinafter, each component which comprises an adhesive composition is demonstrated.

[Acrylic polymer (A)]
The acrylic polymer (A) is a component that becomes a base polymer of the pressure-sensitive adhesive composition. This acrylic polymer (A) differs from the acrylic polymer (A) in that an acrylic polymer (A) previously reacted with a compound (B) described later is used for forming the pressure sensitive adhesive. (A) itself is used in an aspect that contributes to the formation of an adhesive.

  The active hydrogen group in the acrylic polymer (A) is a group containing active hydrogen. Active hydrogen refers to a highly reactive hydrogen atom among hydrogen atoms contained in a molecule. As active hydrogen, a hydrogen atom bonded to an atom other than a carbon atom (for example, an oxygen atom, a nitrogen atom, and a sulfur atom) can be exemplified. The acrylic polymer (A) has an active hydrogen group, so that a compound (B) described later (functional group possessed by the compound (B)) or a crosslinking agent (C) (functional group possessed by the crosslinking agent (C)). It can react with. Examples of the active hydrogen group possessed by the acrylic polymer (A) include a hydroxy group, a carboxy group, an amino group, an amide group, a thiol group, a sulfonic acid group, and a phosphoric acid group. The acrylic polymer (A) preferably has one or more of these active hydrogen groups.

  The acrylic polymer (A) having an active hydrogen group is a polymer ((meth) acrylic ester polymer) containing a structural unit derived from a (meth) acrylic ester, preferably a (meth) acrylic ester. Copolymer. In this specification, when it is simply described as “polymer”, the polymer includes a homopolymer of one monomer and a copolymer of two or more monomers. In the present specification, “structural unit” means a monomer unit constituting a polymer. Examples of the structural unit derived from the monomer include a structural unit in which a polymerizable double bond (C═C) in the monomer is cleaved to form a single bond (—C—C—).

  As the acrylic polymer (A), a polymer of a monomer component containing a (meth) acrylic acid ester having an active hydrogen group, a monomer having an active hydrogen group, and a (meth) acrylic acid ester having no active hydrogen group Examples thereof include a copolymer of monomer components to be contained. That is, the acrylic polymer (A) includes a polymer containing a structural unit derived from a (meth) acrylic acid ester having an active hydrogen group, a structural unit derived from a monomer having an active hydrogen group, and an active hydrogen group. Examples thereof include a copolymer containing a structural unit derived from a (meth) acrylic acid ester that is not present.

  The acrylic polymer (A) may be described as (meth) acrylic acid ester (a1) other than the (meth) acrylic acid ester having an active hydrogen group (hereinafter simply referred to as “(meth) acrylic acid ester (a1)”). And a structural unit derived from a monomer (a2) having an active hydrogen group. Furthermore, the structural unit derived from other monomers other than those may be contained in the acrylic polymer (A). The acrylic polymer (A) contains the (meth) acrylic acid ester (a1) as a main component of the monomer constituting the acrylic polymer (A) (50% by mass or more in the monomer component) and has an active hydrogen group. It is preferable that the monomer component (monomer mixture) containing the monomer (a2) to be polymerized (copolymerized).

((Meth) acrylic acid ester (a1))
As (meth) acrylic acid ester (a1) other than (meth) acrylic acid ester having an active hydrogen group, for example, CH ₂ ═CR ¹ —COO—R ² (R ¹ represents a hydrogen atom or a methyl group, R ² represents an organic group containing no active hydrogen.) The number of carbon atoms in R ² is preferably 1 to 18, more preferably 1-16, 1-12 more preferred. Examples of R ² include an alkyl group, a cycloalkyl group, an alkoxyalkyl group, an aryl group, an aralkyl group, and an alkoxy polyalkylene glycol group.

  As (meth) acrylic acid ester (a1), (meth) acrylic acid alkyl ester is preferable. Examples of (meth) acrylic acid alkyl esters include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, and isobutyl (meth). Acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl ( (Meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl Meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, and octadecyl (meth) acrylate. One of the specific examples of the (meth) acrylic acid alkyl ester listed above may be used alone, or two or more thereof may be used. 1-18 are preferable, as for carbon number of the alkyl group in (meth) acrylic-acid alkylester, 1-16 are more preferable, and 1-12 are more preferable.

  As the (meth) acrylic acid ester (a1), in addition to the (meth) acrylic acid alkyl ester, for example, (meth) acrylic acid cycloalkyl esters such as cyclopentyl (meth) acrylate and cyclohexyl (meth) acrylate; (Meth) acrylic acid alkoxyalkyl esters such as methoxyethyl (meth) acrylate and 2-ethoxyethyl (meth) acrylate; (meth) acrylic acid aryl esters such as phenyl (meth) acrylate; benzyl (meth) acrylate and 2-phenyl (Meth) acrylic acid aralkyl esters such as ethyl (meth) acrylate; methoxydiethylene glycol mono (meth) acrylate, methoxypolyethylene glycol mono (meth) acrylate, methoxydipropylene glycol Rumono (meth) acrylate, and alkoxy polyalkylene glycol mono (meth) acrylates such as ethoxy diethylene glycol (meth) acrylate; and the like. One of the specific examples of the (meth) acrylic acid ester (a1) listed above may be used alone, or two or more thereof may be used.

  The proportion of the (meth) acrylic acid ester (a1) in the acrylic polymer (A) is preferably 50 to 99% by mass based on the total mass of the monomer components constituting the acrylic polymer (A). The ratio of the (meth) acrylic acid ester (a1) is more preferably 60% by mass or more, further preferably 70% by mass or more, based on the total mass of the monomer components constituting the acrylic polymer (A). Moreover, it is more preferable that it is 95 mass% or less, More preferably, it is 90 mass% or less.

(Monomer (a2) having an active hydrogen group)
As the monomer (a2) having an active hydrogen group, a monomer having an active hydrogen group in the molecule and copolymerizable with the above-mentioned (meth) acrylic acid ester (a1) can be used. Examples of such a monomer (a2) include a monomer having a polymerizable double bond and the above-described active hydrogen group. Examples of such a monomer (a2) include a monomer having a hydroxy group as an active hydrogen group, a monomer having a carboxy group, a monomer having an amino group, a monomer having an amide group, and a monomer having a sulfonic acid group. be able to. One of these may be used alone, or two or more may be used.

  As a monomer which has a hydroxy group, the (meth) acrylic acid ester which has a hydroxy group can be mentioned, for example. Specific examples thereof include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. , 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, and other hydroxyalkyl (meth) acrylates; polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, polyethylene glycol-polypropylene glycol mono ( And hydroxy group-terminated polyalkylene glycol mono (meth) acrylates such as meth) acrylate; and glycerin mono (meth) acrylateThe number of carbon atoms of the hydroxyalkyl group in the hydroxyalkyl (meth) acrylate is preferably 2-8, and more preferably 2-6.

  Examples of the monomer having a carboxy group include ethylenically unsaturated carboxylic acids such as (meth) acrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, fumaric acid, and citraconic acid; and β-carboxyethyl (meta ) Carboxy group-containing (meth) acrylates such as acrylates.

  As a monomer which has an amino group, the (meth) acrylic acid ester type monomer which has an amino group (a primary amino group or a secondary amino group) can be mentioned, for example. Specific examples thereof include monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate, monoethylaminopropyl (meth) acrylate, isopropylaminoethyl (meth) acrylate and the like. Mention may be made of alkylaminoalkyl (meth) acrylates. The number of carbon atoms of the monoalkylaminoalkyl group in the monoalkylaminoalkyl (meth) acrylate is preferably 2 to 10, more preferably 2 to 8, and further preferably 2 to 6.

  Examples of the monomer having an amide group include (meth) acrylamide; and N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-methylol (meth) acrylamide, N- (2-hydroxyethyl) (meth) ) N-monoalkyl-substituted acrylamides such as acrylamide, N-propyl (meth) acrylamide, N- (butoxymethyl) (meth) acrylamide, and N-hexyl (meth) acrylamide. The carbon number of the alkyl group in N-monoalkyl-substituted acrylamide is preferably 1-8, and more preferably 1-6.

  Examples of the monomer having a sulfonic acid group include styrene sulfonic acid, allyl sulfonic acid, 2-sulfoethyl (meth) acrylate, 3-sulfopropyl (meth) acrylate, and 2- (meth) acrylamide-2-methylpropane. Examples thereof include sulfonic acids, and salts and hydrates thereof.

  One of the specific examples of the monomer (a2) having an active hydrogen group may be used alone, or two or more thereof may be used. As the monomer (a2) having an active hydrogen group, it is preferable to use at least one of a monomer having a hydroxy group and a monomer having a carboxy group. Among these, it is more preferable to use at least one of hydroxyalkyl (meth) acrylate and ethylenically unsaturated carboxylic acid, and it is more preferable to use at least one of 2-hydroxyethyl (meth) acrylate and (meth) acrylic acid. .

  The ratio of the monomer (a2) having an active hydrogen group in the acrylic polymer (A) is preferably 1 to 50% by mass based on the total mass of the monomer components constituting the acrylic polymer (A). The ratio of the monomer (a2) having an active hydrogen group is more preferably 2% by mass or more, more preferably 5% by mass or more, based on the total mass of the monomer components constituting the acrylic polymer (A). Moreover, it is more preferable that it is 40 mass% or less, More preferably, it is 30 mass% or less.

  In addition to the (meth) acrylic acid ester (a1) and the monomer (a2) having an active hydrogen group, the other monomer (a3) that may be used in the acrylic polymer (A) includes (meth) acrylic acid. Mention can be made of monomers copolymerizable with the ester (a1) and the monomer (a2). Examples of such a monomer (a3) include styrene, α-methylstyrene, vinyl toluene, divinylbenzene, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caprate, glycidyl (meth) acrylate, acrylonitrile, methacrylonitrile and the like. Can be mentioned. One or more of these may be used.

  The acrylic polymer (A) preferably has one or both of a hydroxy group and a carboxy group as an active hydrogen group, and more preferably has at least a hydroxy group. The equivalent of the hydroxy group in the acrylic polymer (A) having a hydroxy group is preferably 0.5 meq / g or more and 2.0 meq / g or less, and 0.6 meq / g or more and 1.8 meq / g or less. Is more preferably 0.8 meq / g or more and 1.5 meq / g or less.

In this specification, the equivalent of the hydroxy group of the acrylic polymer (A) is the milliequivalent (meq / g) of the hydroxy group in 1 g of the acrylic polymer (A), and is calculated from the charged amount of the raw material. Value. Specifically, equivalents of hydroxy groups in the acrylic polymer _{(A) E OH (meq /} g) is the mass W _A of the acrylic polymer contained in the adhesive composition (A) (g), as well as From the substance amount n _OH (mol) of the monomer having a hydroxy group used in the acrylic polymer (A) and the number of hydroxyl groups N _OH (pieces), it can be calculated by the following formula (1).
E _OH = n _OH × N _OH × 1000 / W _A (1)

  The acrylic polymer (A) is the monomer component described above (preferably a monomer component containing the above-mentioned (meth) acrylic acid ester (a1) as a main component and the above-mentioned monomer (a2) having an active hydrogen group). Can be obtained by polymerizing. As a method for polymerizing the acrylic polymer (A), for example, solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization, or the like can be employed. Among these, from the viewpoint that the acrylic polymer (A) is obtained in a solution form and is easy to use as a pressure-sensitive adhesive composition, solution polymerization is preferred. A pressure-sensitive adhesive composition can be obtained by blending at least a compound (B) described later and a crosslinking agent (C) in a solution containing the acrylic polymer (A).

  As an organic solvent used for solution polymerization, an organic solvent generally used for the synthesis of acrylic polymers can be used. Examples of such organic solvents include ester solvents, ketone solvents, alcohol solvents, ether solvents, aromatic hydrocarbon solvents, aliphatic hydrocarbon solvents, and the like. Specific examples of the organic solvent include ethyl acetate, acetone, methyl ethyl ketone, isopropyl alcohol, methyl cellosolve, ethyl cellosolve, toluene, benzene, and n-hexane.

  As a polymerization initiator used for the polymerization of the acrylic polymer (A), a polymerization initiator generally used for the synthesis of an acrylic polymer can be used. Examples of such polymerization initiators include azo initiators such as azobisisobutyronitrile and 2,2′-azobis (2,4-dimethylvaleronitrile), t-butyl hydroperoxide, and benzoyl peroxide. Examples thereof include peroxide-based initiators such as oxides. A polymerization initiator may be used individually by 1 type, and may be used in combination of 2 or more type. In the polymerization of the acrylic polymer (A), the acrylic polymer (A) having a desired molecular weight is obtained by using a catalyst or a polymerization inhibitor in combination, adjusting the polymerization temperature and the polymerization time, if necessary. Can be obtained.

  The weight average molecular weight (Mw) of the acrylic polymer (A) is preferably 100,000 to 1,500,000, preferably 100,000 to 1,200,000 from the viewpoint of the role as a component that becomes the base polymer of the pressure-sensitive adhesive composition. It is more preferable that it is 100,000-1 million. The weight average molecular weight (Mw) is in terms of standard polystyrene measured by gel permeation chromatography (GPC).

The glass transition point (Tg) of the acrylic polymer (A) is preferably −70 to 0 ° C., more preferably −60 to 0 ° C., and −50 to −10 ° C. Further preferred. In the present specification, Tg of the acrylic polymer (A) is a value obtained by DSC measurement when the acrylic polymer (A) is a homopolymer. When the acrylic polymer (A) is a copolymer, the Tg of the acrylic polymer (A) is a theoretical value obtained from the following FOX formula (2) using the Tg of the homopolymer. It is.
1 / Tg = W ₁ / Tg ₁ + W ₂ / Tg ₂ +... W _n / Tg _n (2)
In the above formula (2), Tg is the glass transition temperature of the copolymer of n kinds of monomer components (monomer 1 to n) represents the _{(K), W 1, W} 2, ··· W n is n species each monomer to the total amount of monomer component (1, 2, · · · n) represents the mass fraction _{of, Tg 1, Tg 2, ···} Tg n are each monomer (1, 2, · · · n) The glass transition point (K) of the homopolymer of For example, taking the monomer used in the examples described later as an example, the glass transition point of the homopolymer of the monomer is as follows, and these values are the Tg of the acrylic polymer produced in the examples described later. Used for calculation.
Butyl acrylate (BA): -52 ° C
Ethyl acrylate (EA): -22 ° C
Methyl acrylate (MA): 8 ° C
Hydroxyethyl acrylate (HEA): -15 ° C
Acrylic acid (AAc): 106 ° C

  The content of the acrylic polymer (A) in the pressure-sensitive adhesive composition is preferably 30 to 80% by mass, and preferably 40 to 70% by mass based on the mass of the solid content of the pressure-sensitive adhesive composition. More preferred.

[Compound (B)]
The pressure-sensitive adhesive composition of one embodiment of the present invention has a carbon-carbon double bond and a functional group that reacts with the active hydrogen group in the acrylic polymer (A) and is heated at 90 ° C. for 5 minutes. The compound (B) whose mass change rate is 5% or less is contained.

The mass change rate when heating at 90 ° C. for 5 minutes in the compound (B) is carried out by conducting a test in which the compound (B) is heated at 90 ° C. for 5 minutes in a thermostatic bath, and the mass of the compound (B) before and after the test is calculated. By measuring, it can obtain | require from following formula (3).
[Mass before test−Mass after test] / Mass before test × 100 (%) (3)

  The compound (B) imparts a carbon-carbon double bond to the acrylic polymer (A) that contributes to the formation of the pressure-sensitive adhesive. If the reaction product obtained by reacting the compound (B) with the acrylic polymer (A) in advance is used for the pressure-sensitive adhesive composition and is applied to form a pressure-sensitive adhesive, the reaction product is used to form the pressure-sensitive adhesive. Will contribute. Therefore, the compound (B) used in such an embodiment is different from that which “provides a carbon-carbon double bond to the acrylic polymer (A) contributing to the formation of the pressure-sensitive adhesive”. When the compound (B) “provides a carbon-carbon double bond to the acrylic polymer (A) that contributes to the formation of the pressure-sensitive adhesive”, the pressure-sensitive adhesive composition is applied to form the pressure-sensitive adhesive. The acrylic polymer (A) at the stage before the reaction with the compound (B) proceeds is used, and the stage after the adhesive composition is applied or the stage where the adhesive is formed (for example, It represents that a carbon-carbon double bond is imparted by reacting and bonding the compound (B) to the acrylic polymer (A) in the stage of drying, curing and the like.

  Here, as described above, a reaction product obtained by reacting a compound having a carbon-carbon double bond and a functional group such as the compound (B) with the acrylic polymer (A) in advance is used as an adhesive composition. The case where the pressure-sensitive adhesive is formed will be further described. The reaction between the acrylic polymer (A) and the compound having a carbon-carbon double bond and a functional group such as the compound (B) can be carried out at a temperature of about 40 to 60 ° C., for example. In this case, in order to sufficiently reduce the adhesive strength of the adhesive after irradiation with active energy rays, a compound having a carbon-carbon double bond and a functional group is reacted with the acrylic polymer (A) in advance. It is conceivable to introduce a carbon-carbon double bond. However, if many carbon-carbon double bonds are introduced into the acrylic polymer (A) in advance, gelation tends to occur. When the acrylic polymer (A) is gelled, it cannot be applied and becomes difficult to use as an adhesive composition, so it is necessary to avoid gelation. Therefore, it is necessary to suppress the amount of the compound used for introducing the carbon-carbon double bond into the acrylic polymer (A), and the amount of the carbon-carbon double bond that can be introduced into the acrylic polymer (A) is small. It will be limited.

  Therefore, the present inventors prepared an adhesive composition by blending an acrylic polymer (A), a compound having a carbon-carbon double bond and a functional group, a crosslinking agent, and the like when forming the adhesive. Then, it was studied that it was applied and dried to form an adhesive. With this means, a carbon-carbon double bond can be introduced into the acrylic polymer (A) that contributes to the formation of the pressure-sensitive adhesive when the pressure-sensitive adhesive composition is applied and then dried or cured. It was found that the above-mentioned gelation can be avoided. However, it has been found that the pressure-sensitive adhesive prepared in this way may not sufficiently reduce the adhesive strength after irradiation with active energy rays. This is because the compound described above evaporates when the pressure-sensitive adhesive composition is applied and dried, and the carbon-carbon double bond cannot be effectively introduced into the acrylic polymer (A). it is conceivable that.

  Therefore, as a result of the study by the present inventors, in the pressure-sensitive adhesive composition of one embodiment of the present invention, a compound having a functional group that reacts with a carbon-carbon double bond and an active hydrogen group is used at 90 ° C. for 5 minutes. A compound (B) having a mass change rate of 5% or less when heated is used. Since this compound (B) has a mass change rate of 5% or less, it is difficult to evaporate when the pressure-sensitive adhesive composition is applied and then dried. A double bond can be effectively introduced. Even when the compound having a functional group that reacts with a carbon-carbon double bond and an active hydrogen group is a compound having a mass change rate of more than 5%, when the adhesive composition is applied and dried, In some cases, the compound evaporates and a carbon-carbon double bond cannot be effectively introduced into the acrylic polymer (A).

  In order to effectively reduce the adhesive strength of the pressure-sensitive adhesive by irradiating the pressure-sensitive adhesive formed from the pressure-sensitive adhesive composition with active energy rays, a specific amount of the compound (B) is added to the acrylic polymer (A). It is necessary to use it. Specifically, the equivalent of the carbon-carbon double bond of the compound (B) to the acrylic polymer (A) is 1.9 meq / g or more, or the content of the compound (B) is acrylic. It is necessary to be 30 to 150 parts by mass with respect to 100 parts by mass of the polymer (A), and both of them may be satisfied.

From the viewpoint that the above-described effects are more effectively exhibited, the equivalent of the carbon-carbon double bond of the compound (B) is 1.9 meq / g or more and 4.0 meq / g with respect to the acrylic polymer (A). The lower limit is preferably 2.0 meq / g or more. In this specification, the equivalent of the carbon-carbon double bond of the compound (B) with respect to the acrylic polymer (A) has the compound (B) per 1 g of the acrylic polymer (A) in the pressure-sensitive adhesive composition. It is the milliequivalent (meq / g) of the carbon-carbon double bond, and is a calculated value calculated from the charged amount of raw material. Specifically, carbon - equivalent E carbon double bonds (meq / g) is the mass W _A of the acrylic polymer contained in the adhesive composition (A) (g), and the pressure-sensitive adhesive composition It can be calculated by the following formula (4) from the amount n _B (mol) of the compound (B) contained and the number N (pieces) of carbon-carbon double bonds.
E = n _B × N × 1000 / W _A (4)

  In addition, from the viewpoint of more effectively achieving the above-described effects, the content of the compound (B) in the pressure-sensitive adhesive composition is 30 with respect to 100 parts by mass (solid content) of the acrylic polymer (A) described above. It is preferable that it is -130 mass parts, More preferably, it is 40-120 mass parts, More preferably, it is 50-100 mass parts.

  As a carbon-carbon double bond which a compound (B) has, the carbon-carbon double bond in a (meth) acryloyl group, a vinyl group, etc. can be mentioned, for example. The compound (B) preferably has a (meth) acryloyl group as a group containing a carbon-carbon double bond, and more preferably has a (meth) acryloyl group at one end. This compound (B) can provide a carbon-carbon double bond by adding a (meth) acryloyl group to the acrylic polymer (A) that contributes to the formation of the pressure-sensitive adhesive.

  Moreover, as a functional group which reacts with the active hydrogen group which an acrylic polymer (A) has in a compound (B), an isocyanate group, an epoxy group, a carbodiimide group etc. can be mentioned, for example. The compound (B) preferably has an isocyanate group as a functional group that reacts with an active hydrogen group, and more preferably has an isocyanate group at one end. More preferably, the compound (B) has a (meth) acryloyl group at one end and an isocyanate group at the other end.

  As described above, the compound (B) has a (meth) acryloyl group and a hydroxy group as the compound (B) from the viewpoint that the mass change rate when heated at 90 ° C. for 5 minutes is 5% or less. A reaction product of the monomer (b1) having the polyfunctional isocyanate (b2) is preferable.

  As the monomer (b1), a (meth) acrylic acid ester having a hydroxy group can be used, and one or more of them can be used. Specific examples of the (meth) acrylic acid ester having a hydroxy group include the “monomer having a hydroxy group” in the description of the acrylic polymer (A). As the monomer (b1), among the monomers having a hydroxy group, the aforementioned hydroxyalkyl (meth) acrylate is preferable, 2-hydroxyethyl (meth) acrylate is more preferable, and 2-hydroxyethyl acrylate is further preferable.

The polyfunctional isocyanate (b2) used in the reaction product is a polyisocyanate compound having two or more isocyanate groups in one molecule. 1 type, or 2 or more types of polyfunctional isocyanate (b2) may be used for the said reaction material. Examples of the polyfunctional isocyanate (b2) include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), and (1,4- Diisocyanate compounds such as cyclohexanediyl) bisisocyanate (H ₆ XDI); trimethylolpropane (TMP) adducts of diisocyanate compounds; isocyanurates of diisocyanate compounds; biurets of HDI; allophanates of HDI . Of these, diisocyanate compounds are preferred, and HDI is more preferred.

  As described above, the compound (B) is more preferably a reaction product of a hydroxyalkyl (meth) acrylate and a diisocyanate compound, and a reaction product of 2-hydroxyethyl acrylate and hexamethylene diisocyanate is particularly preferable. The reactant may be a polymer.

[Crosslinking agent (C)]
The pressure-sensitive adhesive composition of one embodiment of the present invention contains a cross-linking agent (C) having two or more functional groups that react with the active hydrogen group of the acrylic polymer (A). In forming the pressure-sensitive adhesive by applying the pressure-sensitive adhesive composition, the active hydrogen group of the acrylic polymer (A) and the crosslinking agent (C) during the drying, curing, etc. after the pressure-sensitive adhesive composition is applied. The crosslinking reaction can proceed with the functional group possessed by. Thereby, it becomes possible to provide moderate adhesive force to the adhesive before active energy ray irradiation formed from the adhesive composition.

  As a functional group which a crosslinking agent (C) has 2 or more, an isocyanate group, an epoxy group, etc. can be mentioned, for example. As a crosslinking agent (C), a polyisocyanate type crosslinking agent, an epoxy type crosslinking agent, etc. can be mentioned, for example, These 1 type (s) or 2 or more types may be used. As the crosslinking agent (C), it is more preferable to use a polyisocyanate compound (polyisocyanate-based crosslinking agent) having two or more isocyanate groups in one molecule.

As the polyisocyanate-based crosslinking agent, specific examples similar to those of the polyfunctional isocyanate (b2) mentioned in the description of the compound (B) can be used. For example, diisocyanate compounds such as HDI, XDI, TDI, MDI, IPDI, and H ₆ XDI; adducts of diisocyanate compounds; isocyanurates of diisocyanate compounds; biurets of HDI; allophanates of HDI, and the like. Among these, it is preferable to use one or two or more polyisocyanate crosslinking agents. Among these, as a crosslinking agent (C), 1 type, or 2 or more types chosen from the group which consists of the adduct body and isocyanurate body of a diisocyanate compound, and the biuret body of HDI are more preferable.

The equivalent of the isocyanate group of the crosslinking agent (C) to the acrylic polymer (A) is preferably 0.1 meq / g or more and 1.5 meq / g or less, and 0.1 meq / g or more and 1.2 meq. / G or less is more preferable, and 0.2 meq / g or more and 1.0 meq / g or less is more preferable. In this specification, the equivalent of the isocyanate group which the crosslinking agent (C) has with respect to the acrylic polymer (A) is the isocyanate group which the crosslinking agent (C) per 1 g of the acrylic polymer (A) in the pressure-sensitive adhesive composition. Is a calculated value calculated from the charged amount of raw material. Specifically, eq E _NCO of isocyanate groups with a crosslinking agent (C) is (meq / g) is the mass W _A of the acrylic polymer contained in the adhesive composition (A) (g), and cross-linking From the substance amount n _C (mol) of the agent (C) (polyisocyanate compound) and the number of isocyanate groups N _NCO (pieces), it can be calculated by the following formula (5).
E _NCO = n _C × N _NCO × 1000 / W _A (5)

  The content of the crosslinking agent (C) in the pressure-sensitive adhesive composition is preferably 0.1 to 30 parts by mass, more preferably 100 parts by mass (solid content) of the aforementioned acrylic polymer (A). Is 0.5 to 25 parts by mass, more preferably 1 to 20 parts by mass. By applying, drying, curing, etc. the pressure-sensitive adhesive composition with the content of the crosslinking agent (C) in the pressure-sensitive adhesive composition within the above range, it has appropriate pressure-sensitive adhesive force and cohesive strength before irradiation with active energy rays. It is possible to form an adhesive.

  The pressure-sensitive adhesive composition according to one embodiment of the present invention may contain a crosslinking agent other than the crosslinking agent (C) (hereinafter sometimes referred to as “other crosslinking agent”). Examples include an aziridine-based crosslinking agent, a melamine resin-based crosslinking agent, a urea resin-based crosslinking agent, an acid anhydride-based crosslinking agent, a polyamine-based crosslinking agent, a metal chelate-based crosslinking agent, and a carbodiimide-based crosslinking agent. One or more of the other crosslinking agents may be used, and among the other crosslinking agents, metal chelate crosslinking agents are preferred.

  Examples of the metal chelate crosslinking agent include metal chelate compounds such as aluminum chelate, zirconium chelate, and titanium chelate. Among these, aluminum chelate is more preferable.

  It is preferable that content of the other crosslinking agent in an adhesive composition is 1 mass part or less (0-1 mass part) with respect to 100 mass parts of above-mentioned acrylic polymers (A), 0.1 It is preferable that it is below mass part (0-0.1 mass part), and it is further more preferable that it is 0.05 mass part or less (0-0.05 mass part).

  The pressure-sensitive adhesive composition of one embodiment of the present invention preferably further contains a polyfunctional monomer (D) having two or more carbon-carbon double bonds. In addition to the above-mentioned components (A) to (C), the polyfunctional monomer (D) is further irradiated with active energy rays on the pressure-sensitive adhesive formed from the pressure-sensitive adhesive composition containing the polyfunctional monomer (D). It becomes possible to more effectively reduce the adhesive strength of the pressure-sensitive adhesive by the two or more carbon-carbon double bonds possessed by.

  The number of carbon-carbon double bonds that the polyfunctional monomer (D) has is preferably 2 to 6. As this carbon-carbon double bond, the carbon-carbon double bond in a (meth) acryloyl group, a vinyl group, etc. can be mentioned, for example. The polyfunctional monomer (D) preferably has two or more (meth) acryloyl groups and more preferably two or more acryloyl groups as a group containing a carbon-carbon double bond.

  Examples of the polyfunctional monomer (D) include 1,3-butanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, ethylene glycol di (Meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol Di (meth) acrylates such as di (meth) acrylate, polypropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and ethoxylated bisphenol A di (meth) acrylate Trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, ethylene oxide modified trimethylolpropane tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, pentaerythritol tri ( Examples thereof include compounds having at least three (meth) acryloyl groups such as (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and glycerol tri (meth) acrylate. These can be used alone or in combination of two or more. Among these, it is preferable to use one or both of dipentaerythritol penta (meth) acrylate and dipentaerythritol hexa (meth) acrylate, and one of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate. Or it is more preferable to use both.

  When the polyfunctional monomer (D) is contained in the pressure-sensitive adhesive composition, the content of the polyfunctional monomer (D) in the pressure-sensitive adhesive composition is 20 to 20 parts by mass with respect to 100 parts by mass of the acrylic polymer (A). It is preferably 90 parts by mass, more preferably 30 to 80 parts by mass, and even more preferably 40 to 80 parts by mass.

[Photoinitiator (E)]
The pressure-sensitive adhesive composition of one embodiment of the present invention preferably contains a photoinitiator (E). Thereby, it becomes possible to make a photoinitiator exist in the adhesive formed by apply | coating, drying, curing, etc. of an adhesive composition. When the pressure-sensitive adhesive is irradiated with light such as ultraviolet rays, the carbon-carbon double bond based on the compound (B) bonded to the acrylic polymer (A) in the pressure-sensitive adhesive can efficiently cause a curing reaction. It is possible to effectively reduce the adhesive strength of the adhesive.

  If, for example, an electron beam or the like is used as the active energy ray, the curing reaction can be caused without causing the pressure-sensitive adhesive composition to contain a photoinitiator, and the pressure-sensitive adhesive strength of the pressure-sensitive adhesive can be reduced. . On the other hand, as described above, if a photoinitiator is included in the pressure-sensitive adhesive composition so that light such as ultraviolet rays and visible light can be used as the active energy ray, the pressure-sensitive adhesive can be used from the viewpoint of use equipment and regulations. The agent composition can be applied to a wide range of adhesives.

  The photoinitiator (E) is not particularly limited as long as it is a compound that generates radicals that contribute to the initiation of radical polymerization upon irradiation with light such as near infrared rays, visible rays, and ultraviolet rays. Examples of the photoinitiator (E) include benzoin alkyl ether initiators such as benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; aromatic ketal initiators such as benzyldimethyl ketal Benzophenone initiators such as benzophenone, benzoylbenzoic acid, and 3,3′-dimethyl-4-methoxybenzophenone; α-hydroxycyclohexyl phenyl ketone, 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-phenyl) Propyl) ketone, [alpha] -hydroxy- [alpha], [alpha] '-dimethylacetophenone, methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, and 2-methyl Aromatic ketone initiators such as ru-1- [4- (methylthio) -phenyl] -2-morpholinopropane-1; thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone Thioxanthone initiators such as 2-dodecylthioxanthone, 2,4-dichlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, and 2,4-diisopropylthioxanthone; benzyl initiators such as benzyl; Benzoin initiators such as 2-methyl-2-hydroxypropiophenone; α-ketol compounds such as 2-methyl-2-hydroxypropiophenone; aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; 1-phenone-1,1-propanedione— 2- (o-et Photoactive oxime compounds such as (cicarbonyl) oxime; 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, 2,4,6-trimethylbenzoylmethoxyphenylphosphine And acylphosphine oxide initiators such as oxide; These can be used alone or in combination of two or more.

  It is preferable that content of the photoinitiator (E) in an adhesive composition is 0.01-10 mass parts with respect to 100 mass parts of above-mentioned acrylic polymers (A), 0.05-5 More preferably, it is part by mass.

  In addition to the components (A) to (E) described above, the pressure-sensitive adhesive composition may contain various additives depending on necessary properties such as the purpose of adjusting the pressure-sensitive adhesive force. Examples of additives include terpene, terpene-phenol, coumarone indene, styrene, rosin, xylene, phenol, and petroleum tackifier resins, antioxidants, ultraviolet absorbers, and fillers. And pigments.

As described in detail above, the pressure-sensitive adhesive composition of one embodiment of the present invention contains the aforementioned acrylic polymer (A), compound (B), and crosslinking agent (C). In forming this pressure-sensitive adhesive composition by applying this pressure-sensitive adhesive composition, when the pressure-sensitive adhesive composition is applied and then dried or cured, the active hydrogen group of the acrylic polymer (A) and the compound (B) The reaction can proceed with the functional group possessed or the functional group possessed by the crosslinking agent (C). Therefore, it is possible to form a pressure-sensitive adhesive having an appropriate pressure-sensitive adhesive force and cohesive strength before irradiation with active energy rays by the pressure-sensitive adhesive composition. Specifically, the pressure-sensitive adhesive composition, 180 ° peel adhesive strength to a stainless steel test plate F ₁ (before irradiation active energy ray adhesive force F ₁₎ is preferably 50 gf / 25 mm or more, more preferably 60 gf / An adhesive that is 25 mm or more can be formed.

  Moreover, in the said adhesive composition, the equivalent of the carbon-carbon double bond which a compound (B) has with respect to an acrylic polymer (A) is 1.9 meq / g or more, or acrylic polymer (A) 100 mass. The content of the compound (B) with respect to parts is 30 to 150 parts by mass. Even if the carbon-carbon double bond is introduced into the acrylic polymer (A) in such an amount, the compound (B) is carbon-carbon doubled relative to the acrylic polymer (A) contributing to the formation of the pressure-sensitive adhesive. Since it provides a bond, gelation of the acrylic polymer (A) can be suppressed. That is, since the reaction between the acrylic polymer (A) and the compound (B) can be caused when the adhesive composition is applied and then dried or cured, the gelation of the acrylic polymer (A) is suppressed. can do. The compound (B) has a mass change rate of 5% or less when heated at 90 ° C. for 5 minutes, and is difficult to evaporate even when dried after applying the pressure-sensitive adhesive composition. Most can be used for the reaction to the acrylic polymer (A) that contributes to the formation of the adhesive. Therefore, a carbon-carbon double bond can be effectively introduced into the acrylic polymer (A).

Therefore, by irradiating active energy rays to the adhesive formed from the above-mentioned adhesive composition, it is possible to cause a curing reaction at the carbon-carbon double bond and to reduce the adhesive force of the adhesive more effectively. It becomes. Specifically, the above-mentioned pressure-sensitive adhesive composition has a 180 ° peel-off adhesive force F ₂ after irradiation of active energy rays on the stainless steel test plate, preferably less than 50 gf / 25 mm, and the above-mentioned adhesive force F A pressure-sensitive adhesive that is 0.2 times or less than ₁ can be formed. The adhesive force F ₂ is more preferably less than 30 gf / mm, further preferably less than 20 gf / 25 mm, more preferably 0.15 times or less of the aforementioned adhesive force F ₁ , 0 More preferably, it is 1 time or less. The above peel adhesion (F ₁ and F ₂₎ is, JIS Z 0237: can be measured according to the test method specified in 2009.

  The pressure-sensitive adhesive composition of one embodiment of the present invention is used for, for example, an adherend to be provided with a pressure-sensitive adhesive; a release sheet for transferring the pressure-sensitive adhesive to the adherend; a pressure-sensitive adhesive sheet to be attached to the adherend It can be used in such a manner that it is applied to a sheet-like substrate to be applied. Among these, the pressure-sensitive adhesive composition is more preferably used for a pressure-sensitive adhesive layer provided on a sheet-like substrate in the pressure-sensitive adhesive sheet. As a suitable adhesive sheet, the adhesive sheet for semiconductor wafer processing, the adhesive sheet for surface protection, a masking tape, etc. can be mentioned, for example.

<Adhesive sheet>
The pressure-sensitive adhesive sheet according to an embodiment of the present invention includes a sheet-like base material and a pressure-sensitive adhesive layer formed of the above-described pressure-sensitive adhesive composition provided on the sheet-like base material. Examples of the form of the pressure-sensitive adhesive sheet include a sheet form, a tape form, and a film form. The pressure-sensitive adhesive sheet of these forms may be formed in a form wound in a roll shape. Moreover, according to the use purpose etc., it may be cut | disconnected to a suitable form or may be stamped.

  The pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet may be provided on one side (one side) of the sheet-like substrate, or may be provided on both sides. The thickness of the pressure-sensitive adhesive layer provided on one surface of the sheet-like substrate is preferably 5 to 100 μm, more preferably 5 to 80 μm, and further preferably 5 to 50 μm.

  Examples of the form of the sheet-like base material include a sheet, a film, a foil, and a tape. As the sheet-like substrate, it is preferable to use a material that transmits an active energy ray used when reducing the adhesive strength of the pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet. Examples of the material for the sheet-like substrate include paper such as Japanese paper, kraft paper, and crepe paper; cloth such as woven fabric and nonwoven fabric; polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyurethane, and ethylene-vinyl acetate. Examples thereof include plastics such as polymers. Although the thickness of a sheet-like base material is not specifically limited, It is preferable that it is 20-300 micrometers, and it is more preferable that it is 30-200 micrometers.

<Method for producing pressure-sensitive adhesive>
The manufacturing method of the adhesive of one Embodiment of this invention is a method of manufacturing the adhesive which adhesive force falls by irradiation of an active energy ray. In this production method, the above-mentioned acrylic polymer (A), the above-mentioned compound (B) and the above-mentioned crosslinking agent (C) are mixed, and the equivalent of the carbon-carbon double bond in the compound (B) is an acrylic polymer (A ) In an amount of 1.9 meq / g or more, or an amount of 30 to 150 parts by mass of the compound (B) with respect to 100 parts by mass of the acrylic polymer (A). The process of preparing an adhesive composition is included. Moreover, this manufacturing method includes the process of advancing reaction of an active hydrogen group after preparing the above-mentioned adhesive composition and apply | coating an adhesive composition to a base material before the reaction of an active hydrogen group advances.

  The active hydrogen group of the acrylic polymer (A) in the stage after the pressure-sensitive adhesive composition is applied or the stage in which the pressure-sensitive adhesive is formed (for example, the stage of drying, curing, etc.) The crosslinking reaction with the functional group of the crosslinking agent (C) can be advanced. This makes it possible to form a pressure-sensitive adhesive having an appropriate pressure-sensitive adhesive force and cohesive strength before irradiation with active energy rays.

  Further, by the production method having the above structure, the acrylic polymer (A) in the stage after the pressure-sensitive adhesive composition is applied or the stage where the pressure-sensitive adhesive is formed (for example, the stage of drying, curing, etc.) A carbon-carbon double bond can be imparted by the reaction of (B). Thereby, even if the equivalent of the carbon-carbon double bond which the compound (B) has with respect to the acrylic polymer (A) is 1.9 meq / g or more, with respect to 100 parts by mass of the acrylic polymer (A). Even when 30 to 150 parts by mass of the compound (B) is blended, gelation of the acrylic polymer (A) can be avoided. Moreover, since the compound (B) hardly evaporates even when the pressure-sensitive adhesive composition is applied and then dried, most of the compound (B) used in the pressure-sensitive adhesive composition is an acrylic resin after the pressure-sensitive adhesive composition is applied. It can be used for the reaction to the polymer (A). Therefore, a carbon-carbon double bond can be effectively introduced into the acrylic polymer (A) forming the pressure-sensitive adhesive, and as a result, the carbon-carbon double bond of the polymer forming the pressure-sensitive adhesive. An adhesive having an increased amount of can be formed. By irradiating the adhesive with active energy rays, a curing reaction can be caused by a carbon-carbon double bond, so that the adhesive strength of the adhesive can be effectively reduced, and the adhesive can be easily removed. It becomes possible to peel.

  Examples of the method for applying the pressure-sensitive adhesive composition to the substrate include a roll coating method, a bar coating method, a screen coating method, a die coating method, a spin coating method, a knife coating method, a blade coating method, a gravure coating method, and a spray coating method. Can be mentioned.

  The base material used as the object which apply | coats an adhesive composition is not specifically limited. Examples of the substrate include an adherend to which an adhesive is to be provided, a release sheet for transferring the adhesive to the adherend, and a sheet-like substrate used for the above-mentioned adhesive sheet. Can do. The above-mentioned pressure-sensitive adhesive sheet can be produced by using the above-mentioned sheet-like base material as a base material to which the pressure-sensitive adhesive composition is applied.

  In the method for producing a pressure-sensitive adhesive according to an embodiment of the present invention, after the pressure-sensitive adhesive composition is applied to a substrate before the reaction of active hydrogen groups in the acrylic polymer (A) proceeds, It is preferable to include a step of drying (drying step). In this drying step, the reaction between the active hydrogen group of the acrylic polymer (A) and the functional groups of the compound (B) and the crosslinking agent (C) can be advanced. As drying temperature in a drying process, it is preferable that it is 50-150 degreeC, It is more preferable that it is 50-130 degreeC, It is further more preferable that it is 60-120 degreeC. The drying time in the drying step is preferably 10 seconds to 60 minutes, more preferably 10 seconds to 30 minutes, and even more preferably 10 seconds to 10 minutes.

  Moreover, after the above-mentioned drying process, it is preferable to further include the process (curing process) of curing the coated material of an adhesive composition. In this curing step, it is possible to proceed the reaction between the active hydrogen group possessed by the acrylic polymer (A) and the functional groups possessed by the compound (B) and the crosslinking agent (C). As temperature in a curing process, it is preferable that it is 5-60 degreeC, It is more preferable that it is 10-50 degreeC, It is more preferable that it is 20-40 degreeC. The humidity in the curing step is preferably 30 to 70% RH, and more preferably 40 to 60% RH. The curing period is preferably 1 day or longer, more preferably 2 days or longer, and even more preferably 3 days or longer.

As above-mentioned, the adhesive of one Embodiment of this invention can take the following structures.
[1] A pressure-sensitive adhesive composition that forms a pressure-sensitive adhesive whose adhesive strength is reduced by irradiation with active energy rays, the acrylic polymer (A) having an active hydrogen group, a carbon-carbon double bond, and the activity When the carbon-carbon double bond is added to the acrylic polymer (A) that has a functional group that reacts with a hydrogen group and contributes to the formation of the pressure-sensitive adhesive, and is heated at 90 ° C. for 5 minutes. A compound (B) having a mass change rate of 5% or less and a crosslinking agent (C) having two or more functional groups that react with the active hydrogen group, and the compound for the acrylic polymer (A) (B) The adhesive composition whose equivalent of the carbon-carbon double bond which (B) has is 1.9 meq / g or more.
[2] A pressure-sensitive adhesive composition that forms a pressure-sensitive adhesive whose adhesive strength is reduced by irradiation with active energy rays, the acrylic polymer (A) having an active hydrogen group, a carbon-carbon double bond, and the activity When the carbon-carbon double bond is added to the acrylic polymer (A) that has a functional group that reacts with a hydrogen group and contributes to the formation of the pressure-sensitive adhesive, and is heated at 90 ° C. for 5 minutes. Containing a compound (B) having a mass change rate of 5% or less and a crosslinking agent (C) having two or more functional groups that react with the active hydrogen group, wherein the content of the compound (B) is The adhesive composition which is 30-150 mass parts with respect to 100 mass parts of acrylic polymers (A).
[3] The acrylic polymer (A) has one or both of a hydroxy group and a carboxy group as the active hydrogen group, and the compound (B) and the crosslinking agent (C) are the active hydrogen groups. The pressure-sensitive adhesive composition according to [1] or [2], which has an isocyanate group as a functional group that reacts with a group.
[4] The acrylic polymer (A) has a hydroxy group as the active hydrogen group, and the equivalent of the hydroxy group of the acrylic polymer (A) is 0.5 meq / g or more and 2.0 meq / g or less. The pressure-sensitive adhesive composition according to any one of the above [1] to [3].
[5] The content of the crosslinking agent (C) is 0.1 to 30 parts by mass with respect to 100 parts by mass of the acrylic polymer (A). Adhesive composition.
[6] The crosslinking agent (C) has an isocyanate group as the functional group, and the equivalent of the isocyanate group of the crosslinking agent (C) with respect to the acrylic polymer (A) is 0.1 meq / g or more. The pressure-sensitive adhesive composition according to any one of [1] to [5], which is 1.5 meq / g or less.
[7] The pressure-sensitive adhesive composition according to any one of [1] to [6], wherein the compound (B) is a reaction product of a hydroxyalkyl (meth) acrylate and a diisocyanate compound.
[8] The pressure-sensitive adhesive composition according to any one of [1] to [7], further containing a polyfunctional monomer (D) having two or more carbon-carbon double bonds.
[9] The pressure-sensitive adhesive composition according to any one of [1] to [8], further containing a photoinitiator (E).
[10] The pressure-sensitive adhesive has a 180 ° peel-off adhesive strength F ₁ of 50 gf / 25 mm or more with respect to the stainless steel test plate, and a 180 ° peel-off adhesive strength after irradiation with the active energy ray on the stainless steel test plate. The pressure-sensitive adhesive composition according to any one of [1] to [9], wherein F ₂ is less than 50 gf / 25 mm and 0.2 times or less of the pressure-sensitive adhesive force F ₁ .

Moreover, the pressure-sensitive adhesive sheet according to one embodiment of the present invention can have the following configuration.
[11] A pressure-sensitive adhesive sheet comprising: a sheet-like base material; and a pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition according to any one of [1] to [10] provided on the sheet-like base material. .

Furthermore, the manufacturing method of the adhesive of one Embodiment of this invention can take the following structures.
[12] A method for producing a pressure-sensitive adhesive whose adhesive strength is reduced by irradiation with active energy rays, comprising an acrylic polymer (A) having an active hydrogen group, a carbon-carbon double bond, and the active hydrogen group A compound (B) having a functional group that reacts and having a mass change rate of 5% or less when heated at 90 ° C. for 5 minutes, and a crosslinking agent (C) having two or more functional groups that react with the active hydrogen group In an amount such that the equivalent of the carbon-carbon double bond in the compound (B) is 1.9 meq / g or more relative to the acrylic polymer (A), or relative to 100 parts by mass of the acrylic polymer (A). The step of preparing the pressure-sensitive adhesive composition by blending the compound (B) in an amount of 30 to 150 parts by mass, and the reaction of the active hydrogen group proceeds after preparing the pressure-sensitive adhesive composition. Before the adhesive After application to the substrate the Narubutsu method of the pressure-sensitive adhesive comprising the steps of advancing the reaction of the active hydrogen group.

  Hereinafter, although the manufacture example, an Example, and a comparative example are given and the further specific example of one Embodiment of this invention mentioned above is demonstrated, this invention is not limited to it. In the following text, “parts” and “%” are based on mass (represented as “parts by mass” and “mass%”, respectively) unless otherwise specified.

<Production of acrylic polymer (A)>
(Production Example 1)
Acrylic polymer A1 was produced using a reactor equipped with a reaction vessel, a stirrer, a reflux condenser, a nitrogen inlet tube, a thermometer, and a dropping tube. Specifically, 80 parts of ethyl acetate and 15 parts of methyl ethyl ketone as a solvent were charged in a reaction vessel in the reaction apparatus, and 0.15 part of azobisisobutyronitrile as an initiator. In the reaction vessel, 41.5 parts of butyl acrylate (hereinafter sometimes referred to as “BA”), 35.2 parts of ethyl acrylate (hereinafter sometimes referred to as “EA”), methyl acrylate ( Hereinafter, it may be described as “MA”. 10 parts, 2-hydroxyethyl acrylate (hereinafter sometimes referred to as “HEA”) 12.5 parts, and acrylic acid (hereinafter referred to as “AAc”) 0.8 parts were dropped from a dropping tube over about 2 hours and polymerized at about 80 ° C. for 7 hours under a nitrogen atmosphere. After completion of the reaction, the mixture was cooled and diluted with ethyl acetate to obtain a solution of acrylic polymer A1 (weight average molecular weight 331,000) having a solid content of 44.0%.

(Production Examples 2 to 6)
In Production Examples 2 to 6, Production Examples except that the usage amounts (unit: parts) of the monomer components (BA, EA, MA, HEA, and AAc) used in Production Example 1 were changed as shown in Table 1. In the same manner as in Example 1, solutions (solid content: 44.0%) of acrylic polymers A2 to A6 were obtained. In addition, the usage-amount (unit: mol) of each monomer shown in Table 1 is the molecular weight of each monomer, BA is 128.17, EA is 100.12, MA is 86.09, HEA is 116.12, AAc is 72.06 is a value calculated from the amount of each monomer used (unit: parts). Table 1 shows the theoretical value of Tg (° C.) of each acrylic polymer (A).

<Preparation of pressure-sensitive adhesive composition>
In the following Examples and Comparative Examples, the acrylic polymer (A), the compound (B), the cross-linking agent (C), the aluminum chelate, the polyfunctional monomer (D), and the photoinitiator (E) are respectively A thing was used.
Acrylic polymer (A): acrylic polymers A1 to A6 produced in Production Examples 1 to 6
Compound (B): Compound (2-hydroxyethyl acrylate (HEA) and 1,6-diisocyanato having an acryloyl group and an isocyanate group and a mass change rate of 0% when heated at 90 ° C. for 5 minutes. Polymerized with hexane (HDI); manufactured by BASF, trade name “Laromer PR9000”)
-Crosslinking agent (C): Polyisocyanate type crosslinking agent having three isocyanate groups in the molecule (hexamethylene diisocyanate (HDI) biuret; manufactured by Asahi Kasei Co., Ltd., trade name "Duranate 24A-100")
・ Aluminum chelate: Aluminum trisacetylacetonate (manufactured by Kawaken Fine Chemical Co., Ltd., trade name “Aluminum Chelate A”)
Polyfunctional monomer (D): dipentaerythritol penta and hexaacrylate (dipentaerythritol pentaacrylate content: 40-50%, manufactured by Toagosei Co., Ltd., trade name “Aronix M-400”)
Photoinitiator (E): 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Lambson, trade name “Speedcure TPO”)

(Examples 1-13 and Comparative Examples 1-10)
Each component (unit: part) shown in the upper part of Tables 2-1 to 2-4 was mixed to prepare pressure-sensitive adhesive compositions of Examples 1 to 13 and Comparative Examples 1 to 10. In Comparative Examples 7 and 8, 2-acryloyloxyethyl isocyanate (hereinafter sometimes referred to as “AOI”; trade name “Karenz AOI” manufactured by Showa Denko KK) may be used instead of the compound (B). When the AOI was heated at 90 ° C. for 5 minutes, the mass change rate was 33.7%.

  In addition, the usage-amount (100.0 parts) in acrylic polymer A1-A6 shown to Tables 2-1 to 2-4 means the usage-amount as solid content. Moreover, the usage-amount (unit: mol) of the compound (B) shown to the said table assumes that the used compound (B) is the monomer which HEA and HDI reacted by 1: 1 (molar ratio). This is a value calculated using the molecular weight (284.32) calculated in the above. The use amount (unit: mol) of the crosslinking agent (C) is calculated using the molecular weight (478.59) calculated on the assumption that the used crosslinking agent (C) is a biuret body (monomer) of HDI. It is the value. The usage amount (unit: mol) of the polyfunctional monomer (D) is such that the content of dipentaerythritol pentaacrylate in the polyfunctional monomer (D) used is 45% and the content of dipentaerythritol hexaacrylate is 55%. It is a value calculated using the molecular weight (554.29) calculated assuming that there is. Further, the amount of AOI used (unit: mol) is a value calculated with the molecular weight of AOI being 141.12.

  In the middle row of Tables 2-1 to 2-4, the number of carbon-carbon double bonds of compound (B) (AOI in the case of Comparative Examples 7 and 8) per gram of acrylic polymer in the pressure-sensitive adhesive composition is shown. Equivalent (in the same table, “equivalent of double bond”), milliequivalent of hydroxy group of acrylic polymer (in the same table, “equivalent of hydroxy group”), and crosslinking agent (C) per 1 g of acrylic polymer. It shows milliequivalents of the isocyanate group having (in the same table, “equivalent of isocyanate group”).

<Production of pressure-sensitive adhesive and pressure-sensitive adhesive sheet>
The pressure-sensitive adhesive compositions of each Example and Comparative Example were applied on a PET film as a substrate. Next, the PET film coated with the pressure-sensitive adhesive composition was placed in a dryer at 100 ° C. and dried for 1 minute to remove the solvent in the pressure-sensitive adhesive composition and form a pressure-sensitive adhesive layer having a thickness of 20 μm. A 38 μm-thick releasable PET film (hereinafter referred to as a release film) was bonded to the surface on which the pressure-sensitive adhesive layer was formed, and then shielded from light in an atmosphere of 23 ° C. and 50% RH. Cured for days. Thus, after apply | coating the adhesive composition to a base material, by drying and curing, the active hydrogen group which an acrylic polymer (A) has, and a compound (B) (in the case of Comparative Examples 7 and 8) A sample for evaluation (adhesive sheet) was prepared by reacting the isocyanate group of AOI) and the crosslinking agent (C). And then. Using the sample for evaluation, the gel fraction and the adhesive strength described below were measured. The results are shown in the lower part of Tables 2-1 to 2-4.

<Measurement of gel fraction>
0.2 g of the pressure-sensitive adhesive layer (pressure-sensitive adhesive film) in the sample for evaluation was weighed (this mass is referred to as W ₁ ), and was immersed in 50 mL of ethyl acetate for 1 day. Thereafter, a 200-mesh wire mesh was weighed (this mass is referred to as W ₂ ), followed by filtration to extract soluble components. Thereafter, it dried sought insoluble part of the mass (W _3). From these measured values, the gel fraction (%) was calculated by the following formula (6). Further, the gel fraction (%) was measured in the same manner for the pressure-sensitive adhesive layer after irradiating the pressure-sensitive adhesive layer with ultraviolet rays (UV) and then left in an atmosphere of 23 ° C. and 50% RH for 1 hour. The UV irradiation conditions at this time were the same as those in the measurement of the adhesive force F _{2 described} below.
Gel fraction (%) = ((W ₃ −W ₂ ) / W ₁ ) · 100 (6)

<Measurement of adhesive strength>
The release film was peeled off from the produced sample for evaluation, and cut into a size of 80 mm × 25 mm to prepare a test piece (adhesive sheet) in which an adhesive layer was provided on a PET film. This test piece was affixed to one side of a stainless steel (SUS) test plate, and was 300 mm / min in the direction of 180 ° in a 23 ° C., 50% RH environment according to the test method specified in JIS Z 0237: 2009. The sample was pulled at a speed, and the initial peel strength (before irradiation with active energy rays) of the stainless steel test plate was measured for F ₁ (gf / 25 mm).

Further, the surface of the test piece prepared in the same manner as described above was irradiated with ultraviolet rays (UV) from the PET film side, and then left in an atmosphere of 23 ° C. and 50% RH for 1 hour, and then the above pulling was performed. The peel adhesive strength F ₂ (gf / 25 mm) for the stainless steel test plate was measured in the same manner as the measurement of the peel adhesive strength F ₁ . For irradiation with ultraviolet rays, an electrodeless lamp D bulb manufactured by Fusion was used, and the irradiation condition was set to a light amount of 800 mJ / cm ² .

As shown in Tables 2-1 to 2-4, it was confirmed that any of the pressure-sensitive adhesive compositions of Examples could form a pressure-sensitive adhesive having an appropriate pressure-sensitive adhesive force before ultraviolet irradiation. Moreover, all the adhesives formed with the adhesive composition of the Example have an adhesive force F ₂ after ultraviolet irradiation of less than 50 gf / 25 mm, and an adhesive force F ₁ before ultraviolet irradiation of 0.2. It was less than double. From these results, it was confirmed that the pressure-sensitive adhesive compositions of the examples could form a pressure-sensitive adhesive capable of effectively reducing the pressure-sensitive adhesive force by irradiation with ultraviolet rays.

Claims (12)

A pressure-sensitive adhesive composition that forms a pressure-sensitive adhesive whose adhesive strength is reduced by irradiation with active energy rays,
An acrylic polymer (A) having an active hydrogen group;
While providing the carbon-carbon double bond to the acrylic polymer (A) having a carbon-carbon double bond and a functional group that reacts with the active hydrogen group and contributing to the formation of the pressure-sensitive adhesive. Compound (B) having a mass change rate of 5% or less when heated at 90 ° C. for 5 minutes,
A crosslinking agent (C) having two or more functional groups that react with the active hydrogen group,
The adhesive composition whose equivalent of the carbon-carbon double bond which the said compound (B) has with respect to the said acrylic polymer (A) is 1.9 meq / g or more. A pressure-sensitive adhesive composition that forms a pressure-sensitive adhesive whose adhesive strength is reduced by irradiation with active energy rays,
An acrylic polymer (A) having an active hydrogen group;
While providing the carbon-carbon double bond to the acrylic polymer (A) having a carbon-carbon double bond and a functional group that reacts with the active hydrogen group and contributing to the formation of the pressure-sensitive adhesive. Compound (B) having a mass change rate of 5% or less when heated at 90 ° C. for 5 minutes,
A crosslinking agent (C) having two or more functional groups that react with the active hydrogen group,
The adhesive composition whose content of the said compound (B) is 30-150 mass parts with respect to 100 mass parts of said acrylic polymers (A). The acrylic polymer (A) has one or both of a hydroxy group and a carboxy group as the active hydrogen group,
The pressure-sensitive adhesive composition according to claim 1 or 2, wherein the compound (B) and the crosslinking agent (C) have an isocyanate group as a functional group that reacts with the active hydrogen group. The acrylic polymer (A) has a hydroxy group as the active hydrogen group,
The pressure-sensitive adhesive composition according to any one of claims 1 to 3, wherein an hydroxy group equivalent of the acrylic polymer (A) is 0.5 meq / g or more and 2.0 meq / g or less.   Content of the said crosslinking agent (C) is 0.1-30 mass parts with respect to 100 mass parts of said acrylic polymers (A), The adhesive composition of any one of Claims 1-4. object. The crosslinking agent (C) has an isocyanate group as the functional group,
The pressure-sensitive adhesive according to any one of claims 1 to 5, wherein an equivalent of an isocyanate group of the cross-linking agent (C) with respect to the acrylic polymer (A) is 0.1 meq / g or more and 1.5 meq / g or less. Agent composition.   The pressure-sensitive adhesive composition according to claim 1, wherein the compound (B) is a reaction product of a hydroxyalkyl (meth) acrylate and a diisocyanate compound.   The pressure-sensitive adhesive composition according to any one of claims 1 to 7, further comprising a polyfunctional monomer (D) having two or more carbon-carbon double bonds.   The pressure-sensitive adhesive composition according to any one of claims 1 to 8, further comprising a photoinitiator (E). The adhesive has a 180 ° peeling adhesive strength F ₁ with respect to the stainless steel test plate of 50 gf / 25 mm or more,
The 180 ° peeling adhesive force F ₂ after irradiation of the active energy ray with respect to the stainless steel test plate is less than 50 gf / 25 mm and 0.2 times or less of the adhesive force F ₁ . 10. The pressure-sensitive adhesive composition according to any one of 9 above.   An adhesive sheet provided with a sheet-like base material and the adhesive layer formed with the adhesive composition of any one of Claims 1-10 provided in the said sheet-like base material. A method for producing a pressure-sensitive adhesive whose adhesive strength is reduced by irradiation with active energy rays,
It has an acrylic polymer (A) having an active hydrogen group, a carbon-carbon double bond, and a functional group that reacts with the active hydrogen group and has a mass change rate of 5% or less when heated at 90 ° C. for 5 minutes. A compound (B) and a cross-linking agent (C) having two or more functional groups that react with the active hydrogen group, the equivalent of the carbon-carbon double bond in the compound (B) is the acrylic polymer (A). 1.9 meq / g relative to 100 parts by weight, or the amount of the compound (B) relative to 100 parts by weight of the acrylic polymer (A) is 30 to 150 parts by weight. Preparing a composition;
After preparing the pressure-sensitive adhesive composition and before applying the pressure-sensitive adhesive composition to a substrate before the reaction of the active hydrogen group proceeds, and a step of proceeding the reaction of the active hydrogen group;
The manufacturing method of the adhesive containing this.