JP7304847B2 - PSA COMPOSITION, PSA SHEET, AND METHOD FOR MANUFACTURING PROCESSED PRODUCT - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pressure-sensitive adhesive sheet that can be easily peeled from an adherend, a pressure-sensitive adhesive composition that enables the production of such a pressure-sensitive adhesive sheet, and a method for producing a processed product using such a pressure-sensitive adhesive sheet. is.

In the process of manufacturing electronic components such as semiconductor chips and laminated ceramic capacitors, adhesive sheets are sometimes used to temporarily fix workpieces such as semiconductor wafers and ceramic green sheet laminates. In such a manufacturing process, for example, an adherend such as a semiconductor wafer or a ceramic green sheet laminate is fixed to an adhesive sheet, cut into a predetermined size, and then the resulting cut pieces are adhesively attached. Separation from the sheet is done.

Here, as the adhesive sheet described above, one that can reduce the adhesion between the adhesive sheet and the adherend at a desired timing is used. According to the pressure-sensitive adhesive sheet, the adhesion between the adhesive sheet and the adherend is reduced after the cut piece is obtained, so that the cut piece can be easily separated from the adhesive sheet.

As a pressure-sensitive adhesive sheet capable of reducing adhesion to an adherend at such desired timing, Patent Documents 1 and 2 disclose an acrylic sheet containing a carboxyl precursor group-containing monomer as a monomer unit constituting a polymer. A pressure-sensitive adhesive sheet is disclosed in which a pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive composition containing a polymer and an acid catalyst or acid generator. In the pressure-sensitive adhesive sheet, due to the action of the acid component generated from the acid catalyst or acid generator, gas is generated from the carboxy precursor group-containing monomer described above, and the gas accumulates at the interface between the pressure-sensitive adhesive sheet and the adherend, resulting in adhesion. The sheet can be easily separated from the adherend.

Patent No. 5577461 Patent No. 5174217

However, in the method of manufacturing an electronic component as described above, from the viewpoint of simplifying the process and increasing the production efficiency, it is required to separate the adhesive sheet from the adherend more easily. Therefore, the present inventors have investigated a method for separating the adhesive sheet from the adherend without applying a force to peel off the adhesive sheet, but the conventional techniques disclosed in Patent Document 1 and Patent Document 2 have been found. A pressure-sensitive adhesive sheet cannot be used in such a method, and requires the application of a peeling force when separated from the adherend. Therefore, a pressure-sensitive adhesive sheet that can be peeled off more easily is desired.

The present invention has been made in view of the actual situation as described above, and includes a pressure-sensitive adhesive sheet that can be easily peeled from an adherend, a pressure-sensitive adhesive composition that enables the production of such a pressure-sensitive adhesive sheet, and such a pressure-sensitive adhesive. An object of the present invention is to provide a method for manufacturing a processed product using a sheet.

In order to achieve the above object, firstly, the present invention provides a (meth)acrylic acid alkyl ester (a1) having an alkyl group having 1 to 12 carbon atoms as a monomer unit constituting a polymer, and a hydrocarbon-based polymer obtained by heating. A (meth)acrylic acid ester copolymer (A) containing a carboxy precursor group-containing monomer (a2) having a carboxy precursor group that releases a gas and changes to a carboxy group, and having an active energy ray-reactive group in a side chain. and an acid generator (B) that generates an acid by at least one of irradiation with an active energy ray and heating, and a photoinitiator (C) (Invention 1 ).

In the pressure-sensitive adhesive sheet provided with the pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive composition of the above invention (Invention 1), the pressure-sensitive adhesive layer is heated in the presence of an acid derived from the acid generator (B) in the pressure-sensitive adhesive layer. The hydrocarbon-based gas released by the release reduces the contact area between the adhesive sheet and the adherend, and the adhesive layer is cured by the irradiation of the active energy ray, reducing the adhesive strength to the adherend. These actions combine to make it possible to very easily peel the pressure-sensitive adhesive sheet from the adherend.

In the above invention (invention 1), the (meth)acrylate copolymer (A) preferably contains a hydroxy group-containing monomer (a3) as a monomer unit constituting the polymer (invention 2).

In the above inventions (inventions 1 and 2), the carboxy precursor group-containing monomer (a2) has a structure in which a secondary carbon atom of an alkyl group having a secondary carbon atom and a (meth)acryloyloxy group are bonded. (Meth)acrylic acid alkyl esters, (meth)acrylic acid alkyl esters having a structure in which the tertiary carbon atom of an alkyl group having a tertiary carbon atom is bonded to a (meth)acryloyloxy group, and benzyl (meth) At least one kind of acrylate is preferable (Invention 3).

In the above inventions (inventions 1 to 3), the carboxy precursor group-containing monomer (a2) is sec-butyl (meth)acrylate, isopropyl (meth)acrylate, sec-hexyl (meth)acrylate, or sec-octyl (meth)acrylate. , sec-nonyl (meth)acrylate, sec-decyl (meth)acrylate, bornyl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, tert-butyl (meth)acrylate, tert-hexyl (meth)acrylate , tert-octyl (meth)acrylate, tert-nonyl (meth)acrylate, tert-decyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, 2-ethyl-2-adamantyl (meth)acrylate, and It is preferably at least one selected from the group consisting of benzyl (meth)acrylate (Invention 4).

In the above inventions (Inventions 1 to 4), the (meth)acrylic acid ester copolymer (A) contains 1% by mass or more of the carboxy precursor group-containing monomer (a2) as a monomer unit constituting the polymer, It is preferably contained in a proportion of 75% by mass or less (Invention 5).

In the above inventions (Inventions 1 to 5), the (meth)acrylic acid ester copolymer (A) preferably contains 2-ethylhexyl acrylate as at least one of the (meth)acrylic acid alkyl esters (a1). (Invention 6).

The second aspect of the present invention provides a pressure-sensitive adhesive sheet (Invention 7) comprising a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition (Inventions 1 to 6).

In the above invention (invention 7), the pressure-sensitive adhesive layer preferably has a thickness of 1 μm or more and 60 μm or less (invention 8).

The above inventions (Inventions 7 and 8) may be used for processing a brittle member (Invention 9). After the processing of the brittle member is completed, it is preferable that the adhesive sheet can be easily peeled off from the brittle member. preferable.

The above inventions (inventions 7 to 9) are preferably used for semiconductor processing (invention 10).

Thirdly, the present invention provides a lamination step of laminating the pressure-sensitive adhesive sheet (inventions 7 to 10) on a work piece, a processing step of processing the work piece on the pressure-sensitive adhesive sheet to obtain a work piece, and An irradiation step of irradiating the adhesive layer of the adhesive sheet laminated on the workpiece with an active energy ray, and heating the adhesive layer of the adhesive sheet laminated on the workpiece. and a peeling step of peeling the adhesive sheet that has undergone the irradiation step and the heating step from the workpiece, wherein the heating step is performed after the completion of the irradiation step. Alternatively, there is provided a method for manufacturing a workpiece characterized in that the irradiation step and the heating step are performed simultaneously (Invention 11).

In the above invention (invention 11), the workpiece is preferably a semiconductor device or a member of a semiconductor device (invention 12).

The pressure-sensitive adhesive sheet according to the present invention can be easily peeled off from an adherend. Moreover, according to the adhesive composition which concerns on this invention, it is possible to manufacture such an adhesive sheet. Furthermore, in the method for producing a processed product according to the present invention, the pressure-sensitive adhesive sheet can be easily peeled off from the adherend.

Embodiments of the present invention will be described below.
[Adhesive composition]
The adhesive composition according to this embodiment contains a (meth)acrylate copolymer (A), an acid generator (B), and a photoinitiator (C).

The (meth)acrylic acid ester copolymer (A) includes, as monomer units constituting the polymer, a (meth)acrylic acid alkyl ester (a1) having an alkyl group having 1 to 12 carbon atoms and a hydrocarbon-based copolymer by heating. It contains a carboxy precursor group-containing monomer (a2) having a carboxy precursor group that releases a gas and changes to a carboxy group. Furthermore, the (meth)acrylic acid ester copolymer (A) has an active energy ray-reactive group in the side chain.

The acid generator (B) is one that generates acid by at least one of irradiation with active energy rays and heating.

In the pressure-sensitive adhesive composition according to the present embodiment, as described above, the (meth)acrylic acid ester copolymer (A) has an active energy ray-reactive group in the side chain, and the pressure-sensitive adhesive composition contains a photoinitiator ( C). By irradiating the adhesive layer formed using the adhesive composition with an active energy ray, the reaction in which the active energy ray-reactive groups are bonded to each other can proceed, thereby resulting in adhesion. The agent layer can be cured. As a result, the pressure-sensitive adhesive sheet provided with the pressure-sensitive adhesive layer has reduced adhesive strength to adherends.

Further, in the adhesive composition according to the present embodiment, as described above, the (meth)acrylic acid ester copolymer (A) contains the carboxy precursor group-containing monomer (a2) as a monomer unit constituting the polymer. Thus, the (meth)acrylic acid ester copolymer (A) has a carboxyl precursor group. Furthermore, the adhesive composition contains an acid generator (B). By applying at least one of irradiation of active energy rays and heating to the pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive composition, an acid is generated from the acid generator (B), and further By heating the adhesive layer in the presence of the acid, the carboxyl precursor group of the (meth)acrylic acid ester copolymer (A) is decomposed to release a hydrocarbon-based gas and to leave the carboxyl group. A reaction occurs. The released hydrocarbon-based gas accumulates at the interface between the adhesive layer and the adherend in the adhesive sheet, thereby reducing the contact area between the adhesive layer and the adherend and increasing the adhesive strength to the adherend. will decrease further.

As described above, in the pressure-sensitive adhesive sheet provided with the pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive composition according to the present embodiment, the effect of reducing the adhesive strength due to the curing of the pressure-sensitive adhesive layer by irradiation with active energy rays (hereinafter referred to as (sometimes referred to as "first action"), and the action of reducing the contact area between the pressure-sensitive adhesive layer and the adherend due to the generation of hydrocarbon gas (hereinafter, sometimes referred to as "second action"). ), the pressure-sensitive adhesive sheet can be easily peeled off from the adherend. Since both of these actions are caused by external stimuli, the detachment from the adherend as described above can be caused at a desired timing.

Here, in the second action, as described above, a carboxy group is generated in the (meth)acrylic acid ester copolymer (A) at the same time as the hydrocarbon-based gas is generated. Therefore, the amount of carboxy groups present in the (meth)acrylic acid ester copolymer (A) increases as the amount of released hydrocarbon gas increases. Here, in general, as the amount of carboxyl groups in the adhesive layer increases, the adhesive strength of the adhesive layer tends to increase. Therefore, when the peeling from the adherend is caused only by the second action related to the generation of the hydrocarbon-based gas, as in the case of the conventional adhesive sheet, the generated hydrocarbon-based gas adheres the adhesive layer to the adherend. While the contact area with the body is reduced and peeling is promoted, the adhesive force itself of the adhesive layer is difficult to sufficiently decrease. However, according to the adhesive composition according to the embodiment of the present application, in addition to the second effect related to the generation of hydrocarbon gas, the first effect of reducing the adhesive strength due to the curing of the adhesive layer also occurs. It becomes possible to easily peel off from the body.

In addition, since the adhesive force to the adherend is lowered by the first action, the hydrocarbon-based gas generated by the second action easily separates the adhesive layer and the adherend. In addition, further hydrocarbon-based gas is likely to accumulate in such a separated portion, so that separation of the adhesive layer and the adherend is facilitated from this portion as a starting point. Therefore, in the pressure-sensitive adhesive sheet obtained using the pressure-sensitive adhesive composition according to the present embodiment, the synergistic action of the first action and the second action achieves very easy peeling from the adherend. can do.

In addition, according to the pressure-sensitive adhesive composition according to the present embodiment, the adhesiveness between the pressure-sensitive adhesive sheet and the adherend can be significantly reduced, so that the pressure-sensitive adhesive sheet can be applied without applying a force to peel off the pressure-sensitive adhesive sheet. It can also be peeled off from the adherend. For example, the self-weight of the adhesive sheet or the adherend can be used to separate the adhesive sheet from the adherend. Specifically, in a laminate in which an adhesive sheet is attached to an adherend, the adhesive sheet can be directed downward, and the adhesive sheet can be dropped from the adherend by gravity to separate the adhesive sheet. In this specification, the term “self-peeling” means that the pressure-sensitive adhesive sheet is peeled off from the adherend or peeled off without applying a force to peel off the pressure-sensitive adhesive sheet. Such properties are referred to as "self-peeling properties".

1. (Meth) acrylic acid ester copolymer (A)
The (meth)acrylic acid ester copolymer (A) in the present embodiment is a (meth)acrylic acid alkyl ester (a1) having an alkyl group having 1 to 12 carbon atoms as a monomer unit constituting the polymer, and by heating It is not particularly limited as long as it contains a carboxy precursor group-containing monomer (a2) having a carboxy precursor group that releases a hydrocarbon gas and changes to a carboxy group and has an active energy ray-reactive group in the side chain.

From the viewpoint of being easy to produce and to easily achieve desired performance, the (meth)acrylic acid ester copolymer (A) contains the (meth)acrylic acid alkyl ester (a1) and the carboxy precursor group-containing monomer (a2 an acrylic copolymer (AP) obtained by copolymerizing a monomer containing ), and an active energy ray containing a functional group capable of reacting with the acrylic copolymer (AP) and an active energy ray-reactive group It is preferably obtained by reacting with a reactive group-containing compound (AC). Hereinafter, the case where the (meth)acrylic acid ester copolymer (A) is obtained by the reaction of the acrylic copolymer (AP) and the active energy ray-reactive group-containing compound (AC) will be described. .

Examples of (meth)acrylic acid alkyl esters (a1) having an alkyl group having 1 to 12 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and n-butyl (meth)acrylate. , n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate and the like. . A pressure-sensitive adhesive obtained by an acrylic copolymer (AP) containing, as a monomer constituting the polymer, a (meth)acrylic acid alkyl ester (a1) having an alkyl group having 1 to 12 carbon atoms is desired. of adhesiveness can be expressed. From this point of view, among the above-described alkyl (meth)acrylates, it is preferable to use alkyl (meth)acrylates having alkyl groups of 1 to 8 carbon atoms, particularly n-butyl (meth)acrylate and 2 -Ethylhexyl (meth)acrylate, more preferably 2-ethylhexyl (meth)acrylate. In addition, these may be used independently and may be used in combination of 2 or more type.

The acrylic copolymer (AP) preferably contains a monomer having a glass transition temperature (Tg) of 0° C. or less as a homopolymer as at least one of the (meth)acrylic acid alkyl esters (a1) described above. In particular, it preferably contains a monomer having a glass transition temperature (Tg) of −40° C. or lower as a homopolymer, more preferably a monomer having a glass transition temperature (Tg) of −60° C. or lower as a homopolymer. The carboxy precursor group-containing monomer (a2) contained as a monomer of the acrylic copolymer (AP) tends to have a relatively high glass transition temperature (Tg) as a homopolymer, so the acrylic copolymer (AP) contains a monomer having a glass transition temperature (Tg) of 0 ° C. or less as a homopolymer, so that the resulting (meth)acrylic acid ester copolymer (A) as a whole has a glass transition temperature (Tg) at an appropriate temperature. Easy to adjust. As a result, the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to the present embodiment has good adhesive strength to the adherend (before the pressure-sensitive adhesive layer is irradiated with an active energy ray and heated). Therefore, the adhesive strength in the state where the first action and the second action described above are not occurring (hereinafter sometimes referred to as "initial adhesive strength") can be easily exhibited. From this point of view as well, it is preferable to use at least one of n-butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate as the (meth)acrylic acid alkyl ester (a1) described above, particularly 2- Preference is given to using ethylhexyl (meth)acrylate.

The acrylic copolymer (AP) preferably contains 10% by mass or more, particularly 20% by mass or more, of the (meth)acrylic acid alkyl ester (a1) described above as a monomer unit constituting the polymer. preferably, more preferably 30% by mass or more. In addition, the acrylic copolymer (AP) preferably contains the above-mentioned (meth)acrylic acid alkyl ester (a1) as a monomer unit constituting the polymer in an amount of 90% by mass or less, particularly 80% by mass. % or less, more preferably 70 mass % or less. When the content of the (meth)acrylic acid alkyl ester (a1) is 10% by mass or more, the pressure-sensitive adhesive layer to be obtained easily exhibits desired initial pressure-sensitive adhesive strength. In addition, when the content of the (meth)acrylic acid alkyl ester (a1) is 90% by mass or less, the adhesive strength can be favorably reduced when the resulting adhesive layer is irradiated with an active energy ray. become a thing.

The carboxy precursor group-containing monomer (a2) has a carboxy precursor group that releases a hydrocarbon gas when heated in the presence of an acid and changes to a carboxy group, and can constitute an acrylic copolymer (AP). If so, it is not particularly limited.

A preferred example of the carboxyl precursor group-containing monomer (a2) is a (meth)acrylic acid alkyl ester having a structure in which a secondary carbon atom of an alkyl group having a secondary carbon atom is bonded to a (meth)acryloyloxy group. , (meth)acrylic acid alkyl ester having a structure in which a tertiary carbon atom of an alkyl group having a tertiary carbon atom and a (meth)acryloyloxy group are bonded, and benzyl (meth)acrylate. .

Preferable examples of the (meth)acrylic acid alkyl ester having a structure in which the secondary carbon atom of the alkyl group having a secondary carbon atom and the (meth)acryloyloxy group are bonded include sec-butyl (meth ) acrylate, isopropyl (meth) acrylate, sec-hexyl (meth) acrylate, sec-octyl (meth) acrylate, sec-nonyl (meth) acrylate, sec-decyl (meth) acrylate, bornyl (meth) acrylate, isobornyl (meth) acrylate ) acrylate, cyclohexyl (meth)acrylate and the like.

Preferable examples of the (meth)acrylic acid alkyl ester having a structure in which the tertiary carbon atom of the alkyl group having a tertiary carbon atom and the (meth)acryloyloxy group are bonded include tert-butyl (meth ) acrylate, tert-hexyl (meth)acrylate, tert-octyl (meth)acrylate, tert-nonyl (meth)acrylate, tert-decyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, 2-ethyl -2-adamantyl (meth)acrylate and the like.

Among the above preferred examples of the carboxy precursor group-containing monomer (a2), sec-butyl (meth)acrylate, isopropyl (meth)acrylate, tert-butyl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate and Preference is given to using at least one benzyl (meth)acrylate, in particular tert-butyl (meth)acrylate. By using tert-butyl (meth)acrylate as the carboxyl precursor group-containing monomer (a2), it becomes easy to favorably release a hydrocarbon-based gas, thereby preventing the pressure-sensitive adhesive sheet according to the present embodiment from the adherend. It becomes possible to perform peeling more easily.

In addition, the preferred examples of the carboxyl precursor group-containing monomer (a2) described above may be used alone, or two or more of them may be used in combination.

The acrylic copolymer (AP) preferably contains 1% by mass or more, more preferably 10% by mass or more, of the carboxy precursor group-containing monomer (a2) as a monomer unit constituting the polymer. In particular, it is preferably contained in an amount of 35% by mass or more, more preferably 40% by mass or more. Further, the acrylic copolymer (AP) preferably contains 75% by mass or less, particularly 65% by mass or less, of the carboxyl precursor group-containing monomer (a2) as a monomer unit constituting the polymer. preferably, more preferably 55% by mass or less. When the content of the carboxyl precursor group-containing monomer (a2) is 1% by mass or more, a hydrocarbon-based gas is favorably generated from the pressure-sensitive adhesive layer during the above-described second action, which is the present embodiment. It becomes possible to more easily peel off the adhesive sheet according to the above from the adherend. Further, when the content of the carboxy precursor group-containing monomer (a2) is 75% by mass or less, it becomes easy to sufficiently ensure the content of the (meth)acrylic acid alkyl ester (a1) and other monomers described above. , the pressure-sensitive adhesive sheet according to the present embodiment can easily achieve a desired adhesive strength, and the pressure-sensitive adhesive layer can be easily cured by the first action described above.

The acrylic copolymer (AP) contains, as monomer units constituting the polymer, a hydroxy group-containing monomer (a3) together with the (meth)acrylic acid alkyl ester (a1) and the carboxy precursor group-containing monomer (a2) described above. preferably included. The acrylic copolymer (AP) contains a hydroxyl group-containing monomer (a3) as a monomer unit constituting the polymer, so that the acrylic copolymer (AP) contains a hydroxyl group as a side chain. . Here, the hydroxy group is capable of functioning as a reaction point with the active energy ray-reactive group-containing compound (AC), whereby the (meth)acrylic (meth)acrylic It becomes easy to obtain the acid ester copolymer (A). In addition, when the pressure-sensitive adhesive composition in the present embodiment contains a cross-linking agent (especially a polyisocyanate-based compound), which will be described later, the above-mentioned hydroxy group can also function as a reaction point with the cross-linking agent, which is favorable. It becomes easy to obtain a crosslinked adhesive.

Preferred examples of the hydroxy group-containing monomer (a3) include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3 -Hydroxyalkyl (meth)acrylates such as hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyheptyl (meth)acrylate, and 8-hydroxyoctyl (meth)acrylate. Among these, 2-hydroxyethyl (meth)acrylate is preferable from the viewpoint of excellent reactivity with the above-described cross-linking agent and active energy ray-reactive group-containing compound (AC). These may be used alone or in combination of two or more.

The acrylic copolymer (AP) preferably contains 1% by mass or more, particularly preferably 5% by mass or more, of the hydroxy group-containing monomer (a3) as a monomer unit constituting the polymer. Furthermore, it is preferable to contain 8 mass % or more. Further, the acrylic copolymer (AP) preferably contains 50% by mass or less, particularly 40% by mass or less, of the hydroxy group-containing monomer (a3) as a monomer unit constituting the polymer. It is preferable that the content is 25% by mass or less. When the content of the hydroxy group-containing monomer (a3) is 1% by mass or more, it is possible to favorably cause the reaction with the cross-linking agent and the active energy ray-reactive group-containing compound (AC) as described above. becomes. In addition, since the content of the hydroxy group-containing monomer (a3) is 50% by mass or less, the content of the (meth)acrylic acid alkyl ester (a1) and the carboxy precursor group-containing monomer (a2) described above is sufficiently ensured. This makes it easy to perform the above-described first action and second action.

If desired, the acrylic copolymer (AP) may contain, as the monomer units constituting the copolymer, the (meth)acrylic acid alkyl ester (a1), the carboxy precursor group-containing monomer (a2), and the hydroxy group-containing monomer. Other monomers than (a3) may be contained.

Examples of such other monomers include monomers having reactive groups capable of reacting with cross-linking agents such as carboxy groups, amino groups and aziridinyl groups. In particular, monomers containing a carboxy group include, for example, ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Examples of monomers containing amino groups include aminoethyl (meth)acrylate and n-butylaminoethyl (meth)acrylate. These monomers can be used singly or in combination of two or more.

Further examples of other monomers mentioned above include alkoxyalkyl group-containing (meth)acrylic acids such as methoxymethyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxymethyl (meth)acrylate, ethoxyethyl (meth)acrylate, etc. Ester; (meth)acrylic acid ester having an aromatic ring such as phenyl (meth)acrylate; non-crosslinkable acrylamide such as acrylamide and methacrylamide; N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethyl Examples thereof include (meth)acrylic acid esters having a non-crosslinkable tertiary amino group such as aminopropyl (meth)acrylate; vinyl acetate; styrene; These may be used alone or in combination of two or more.

The polymerization mode of the acrylic copolymer (AP) may be a random copolymer or a block copolymer. Also, the acrylic copolymer (AP) can be obtained by copolymerizing each of the monomers described above by a conventional method. For example, it can be produced by polymerization by an emulsion polymerization method, a solution polymerization method, a suspension polymerization method, a bulk polymerization method, an aqueous solution polymerization method, or the like. Among them, from the viewpoint of stability during polymerization and ease of handling during use, it is preferable to produce by a solution polymerization method carried out in an organic solvent.

For example, after dissolving a mixture of monomer components in an organic solvent, conventionally known azobisisobutyronitrile, 2,2′-azobis(2-aminodipropane) dihydrochloride, 4,4′-azobis(4 -cyanovaleric acid) or a peroxide polymerization initiator such as benzoyl peroxide is added and radical polymerization is carried out to produce an acrylic copolymer (AP).

The weight average molecular weight of the acrylic copolymer (AP) is preferably 100,000 or more, particularly preferably 200,000 or more, and further preferably 300,000 or more. Also, the weight average molecular weight is preferably 2,000,000 or less, particularly preferably 1,000,000 or less, further preferably 800,000 or less. When the weight-average molecular weight of the acrylic copolymer (AP) is within the above range, it becomes easy to form a pressure-sensitive adhesive layer having a desired initial pressure-sensitive adhesive strength. In addition, the mass average molecular weight in this specification is the value of standard polystyrene conversion measured by the gel permeation chromatography (GPC) method.

The active energy ray-reactive group-containing compound (AC) is not particularly limited as long as it has a functional group capable of reacting with the acrylic copolymer (AP) and contains an active energy ray-reactive group.

Examples of functional groups that can react with the acrylic copolymer (AP) include isocyanate groups, epoxy groups, carboxy groups, and the like. Here, when the acrylic copolymer (AP) contains the above-described hydroxy group-containing monomer (a3) as a monomer constituting the polymer, the active energy ray-reactive group-containing compound (AC) is It preferably has an isocyanate group that is highly reactive with the hydroxy group derived from the monomer.

The active energy ray-reactive group is preferably an energy ray-curable carbon-carbon double bond, and particularly preferably a (meth)acryloyl group. The active energy ray-reactive group-containing compound (AC) preferably has 1 to 5, more preferably 1 to 2, active energy ray-reactive groups in one molecule.

Examples of active energy ray-reactive group-containing compounds (AC) include 2-methacryloyloxyethyl isocyanate, meta-isopropenyl-α,α-dimethylbenzyl isocyanate, methacryloyl isocyanate, allyl isocyanate, 1,1-(bisacryloyloxy Methyl) ethyl isocyanate; Acryloyl monoisocyanate compound obtained by reaction of diisocyanate compound or polyisocyanate compound and hydroxyethyl (meth) acrylate; Diisocyanate compound or polyisocyanate compound, polyol compound and hydroxyethyl (meth) acrylate acryloyl monoisocyanate compounds obtained by reaction, and the like. Among these, 2-methacryloyloxyethyl isocyanate is preferred because it is easy to introduce an active energy ray-reactive group into the acrylic copolymer (AP), thereby easily causing the first action described above. preferable. The active energy ray-reactive group-containing compound (AC) may be used alone or in combination of two or more.

The (meth)acrylic acid ester copolymer (A) in the present embodiment contains 10 mol% or more of the active energy ray-reactive group-containing compound (AC) with respect to the hydroxy groups of the acrylic copolymer (AP). It is preferable that the ratio is 40 mol% or more, and more preferably 70 mol% or more. is preferred. In addition, the (meth)acrylic acid ester copolymer (A) in the present embodiment contains 99 mol of the active energy ray-reactive group-containing compound (AC) with respect to the hydroxy groups of the acrylic copolymer (AP). % or less, more preferably 90 mol % or less, and more preferably 85 mol % or less. Preferably. The (meth)acrylate copolymer (A) is obtained by reacting the acrylic copolymer (AP) and the active energy ray-reactive group-containing compound (AC) in the above-described ratio, A sufficient number of active energy ray-reactive groups are introduced, and the above-described first action is likely to occur.

The reaction between the acrylic copolymer (AP) and the active energy ray-reactive group-containing compound (AC) may be carried out by a conventional method. Through this reaction step, the hydroxy group in the acrylic copolymer (AP) reacts with the functional group (e.g., isocyanate group) in the active energy ray-reactive group-containing compound (AC) to react with the active energy ray-reactive A group is introduced as a side chain of the acrylic copolymer (AP) to obtain an energy ray-curable (meth)acrylate copolymer (A).

The (meth)acrylic acid ester copolymer (A) has a mass average molecular weight of preferably 200,000 or more, particularly preferably 300,000 or more, further preferably 400,000 or more. Also, the weight average molecular weight is preferably 2,000,000 or less, particularly preferably 1,000,000 or less, further preferably 800,000 or less.

The pressure-sensitive adhesive composition according to the present embodiment may contain one type of the (meth)acrylate copolymer (A) described above, or may contain two or more types. good too. Further, the pressure-sensitive adhesive composition according to the present embodiment may contain another (meth)acrylic ester copolymer together with the (meth)acrylic ester copolymer (A) described above. .

2. Acid generator (B)
As the acid generator (B), an acid is generated by at least one of irradiation with an active energy ray and heating, and the acid generates a carboxy precursor group-containing monomer (a2) in the (meth)acrylic acid ester copolymer (A). There is no particular limitation as long as the hydrocarbon-based gas can be sufficiently released from the portion derived from.

When the acid generator (B) is one that generates an acid upon irradiation with an active energy ray, examples of such acid generator (B) include an ester compound of N-hydroxynaphthalimide and an acid component, or an ester compound thereof. Derivatives, onium salts, and the like, and examples of the onium salts include sulfonium salts, iodonium salts, diazonium salts, selenium salts, pyridinium salts, ferrocenium salts, phosphonium salts, thiopyrinium salts, and the like.

Examples of the acid component in the above ester compound of N-hydroxynaphthalimide and acid component or derivatives thereof include trifluoromethanesulfonic acid, methanesulfonic acid, benzenesulfonic acid and the like.

Examples of anion components in the above-mentioned onium salts include CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (CF ₃ SO ₂ ) ₃ C ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , SbF ₆ ^- , B(C ₆ F ₅ ) ₄ ^- and the like.

In particular, the acid generator (B) in the present embodiment is preferably an ester compound of N-hydroxynaphthalimide and an acid component or a derivative thereof, more preferably an N-hydroxy Ester compounds of naphthalimide and trifluoromethanesulfonic acid or derivatives thereof are preferred, and 1,8-naphthalimide trifluoromethanesulfonic acid esters or derivatives thereof are particularly preferred.

Further, when the acid generator (B) is one that generates an acid by irradiation with an active energy ray, the type of the active energy ray is preferably an ultraviolet ray, an electron beam, or the like, and is particularly easy to handle. In addition, it is preferable that the ultraviolet ray is capable of effectively generating an acid.

On the other hand, when the acid generator (B) generates an acid by heating, examples of the acid generator (B) include N-(4-methylbenzyl)4'-pyridinium hexafluoroantimonate. hydrazinium salts; phosphonium salts; sulfonium salts such as dimethylphenylsulfonium hexafluorophosphate; vinyl ether adduct derivatives of carboxylic acid such as propyl vinyl ether of 1,2,4-trimellitic acid;

The acid generator (B) described above can be used alone or in combination of two or more.

The content of the acid generator (B) in the pressure-sensitive adhesive composition according to the present embodiment is preferably 0.5 parts by mass or more with respect to 100 parts by mass of the (meth)acrylate copolymer (A). In particular, it is preferably 1 part by mass or more, more preferably 2 parts by mass or more. In addition, the content is preferably 20 parts by mass or less, particularly preferably 15 parts by mass or less, and further preferably 10 parts by mass with respect to 100 parts by mass of the (meth)acrylic acid ester copolymer (A) It is preferably less than or equal to parts. When the content of the acid generator (B) is 0.5 parts by mass or more, it is possible to effectively generate an acid in the resulting pressure-sensitive adhesive layer, thereby producing a (meth)acrylic acid ester copolymer. Hydrocarbon-based gas can be favorably generated from (A), and as a result, the adhesive sheet can be more easily peeled from the adherend. In addition, when the content of the acid generator (B) is 20 parts by mass or less, it becomes easier to maintain a good surface condition when forming a coating film using the pressure-sensitive adhesive composition according to the present embodiment. .

3. Photoinitiator (C)
The photoinitiator (C) is capable of promoting the reaction in the active energy ray-reactive group of the (meth)acrylic acid ester copolymer (A) caused by the irradiation of the active energy ray. As a result, as long as it is possible to promote the curing of the adhesive layer formed from the adhesive composition according to the present embodiment, it is not particularly limited, but the photoradical polymerization initiator is a reactive surface. preferred from

Examples of such photoinitiators (C) include benzoin compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, thioxanthone compounds, peroxide compounds, etc. Specifically, 1-hydroxycyclohexylphenyl Ketones, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyldiphenylsulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, β-chloranthraquinone, 2,4,6-trimethyl Examples include benzoyldiphenylphosphine oxide. Among these, acetophenone compounds are preferred, and 1-hydroxycyclohexylphenyl ketone is more preferred, from the viewpoint of being able to effectively promote the reaction at the active energy ray-reactive group. These photoinitiators (C) can be used individually by 1 type or in combination of 2 or more types.

The content of the photoinitiator (C) in the adhesive composition according to the present embodiment is preferably 0.1 parts by mass or more with respect to 100 parts by mass of the (meth)acrylic acid ester copolymer (A). In particular, it is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more. In addition, the content is preferably 10 parts by mass or less, particularly preferably 8 parts by mass or less, and further preferably 5 parts by mass with respect to 100 parts by mass of the (meth)acrylic acid ester copolymer (A) It is preferably less than or equal to parts. When the content of the photoinitiator (C) is within the range described above, the reaction in the active energy ray-reactive group can be effectively promoted, and as a result, the adhesive sheet can be peeled off from the adherend more easily. It becomes possible to do it easily.

4. Crosslinking agent (D)
The pressure-sensitive adhesive composition according to this embodiment preferably contains a cross-linking agent (D). By including the cross-linking agent (D) in the pressure-sensitive adhesive composition, a cross-linking reaction between the (meth)acrylic acid ester copolymer (A) and the cross-linking agent (D) can occur, and the pressure-sensitive adhesive according to the present embodiment A three-dimensional network structure can be satisfactorily formed in the pressure-sensitive adhesive layer formed from the agent composition. This facilitates formation of a pressure-sensitive adhesive layer having desired adhesive strength.

The cross-linking agent (D) is not particularly limited as long as it can cause a cross-linking reaction with the (meth)acrylic acid ester copolymer (A), and includes polyisocyanate-based compounds, epoxy-based compounds, Metal chelate compounds, polyimine compounds such as aziridine compounds, melamine resins, urea resins, dialdehydes, methylol polymers, metal alkoxides, metal salts and the like. Among these, polyisocyanate-based compounds or epoxy-based compounds are preferred, and polyisocyanate-based compounds are particularly preferred, for reasons such as easy control of the cross-linking reaction.

A polyisocyanate-based compound is a compound having two or more isocyanate groups per molecule. Specifically, aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate; Their biuret forms, isocyanurate forms, and adducts which are reaction products with low-molecular-weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil can also be mentioned. Among these, trimethylolpropane-modified tolylene diisocyanate is preferred.

Examples of epoxy compounds include 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylylenediamine, ethylene glycol diglycidyl ether. , 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidylaniline, diglycidylamine and the like.

When the pressure-sensitive adhesive composition according to the present embodiment contains the cross-linking agent (D), the content of the cross-linking agent (D) is 0 per 100 parts by mass of the (meth)acrylic acid ester copolymer (A). It is preferably at least 0.1 part by mass, particularly preferably at least 0.2 part by mass, and more preferably at least 0.3 part by mass. In addition, the content is preferably 20 parts by mass or less, particularly preferably 15 parts by mass or less, and further preferably 10 parts by mass with respect to 100 parts by mass of the (meth)acrylic acid ester copolymer (A) It is preferably less than or equal to parts. When the content of the cross-linking agent (D) is within the range described above, the cross-linking reaction between the (meth)acrylic acid ester copolymer (A) and the cross-linking agent (D) occurs appropriately, thereby achieving the desired adhesiveness. It becomes easy to form a pressure-sensitive adhesive layer having strength.

5. Other components In addition to the above components, the adhesive composition according to the present embodiment may contain various additives such as coloring materials such as dyes and pigments, flame retardants, fillers, plasticizers, and antistatic agents. However, it is preferable to use only those additives that do not inhibit the transmission of ultraviolet rays.

6. Method for producing pressure-sensitive adhesive composition The pressure-sensitive adhesive composition according to the present embodiment is produced by producing a (meth)acrylic acid ester copolymer (A), and the resulting (meth)acrylic acid ester copolymer (A) and , an acid generator (B), a photoinitiator (C), and, if desired, a cross-linking agent (D), and an additive. The mixing may be performed in a solvent, and in this case, a coating liquid of the pressure-sensitive adhesive composition can be obtained.

Examples of the solvent include aliphatic hydrocarbons such as hexane, heptane and cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as methylene chloride and ethylene chloride; alcohols such as methoxy-2-propanol; ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone and cyclohexanone; esters such as ethyl acetate and butyl acetate; cellosolve solvents such as ethyl cellosolve;

The concentration/viscosity of the coating liquid thus prepared is not particularly limited as long as it is within a range that allows coating, and can be appropriately selected according to the situation. For example, it is diluted so that the concentration of the adhesive composition is 10% by mass or more and 60% by mass or less. When obtaining the coating liquid, it is not necessary to add a solvent or the like, and if the adhesive composition has a viscosity that allows coating, the solvent may not be added.

[Adhesive sheet]
The pressure-sensitive adhesive sheet according to this embodiment includes a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to this embodiment. The pressure-sensitive adhesive sheet according to the present embodiment may be a single-sided pressure-sensitive adhesive sheet comprising a substrate laminated on one side of the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer is laminated on both sides of the substrate. A double-sided pressure-sensitive adhesive sheet with a substrate may be used, or a double-sided pressure-sensitive adhesive sheet without a substrate may be used. In the case of a double-sided pressure-sensitive adhesive sheet with a substrate, only one pressure-sensitive adhesive layer may be formed from the pressure-sensitive adhesive composition according to the present embodiment, or both pressure-sensitive adhesive layers may be formed from the pressure-sensitive adhesive composition according to the present embodiment. It may be formed from In addition, the pressure-sensitive adhesive sheet according to the present embodiment is a surface of the pressure-sensitive adhesive layer that is attached to the adherend (hereinafter referred to as "adhesive ) may be laminated with a release sheet.

1. Configuration of PSA Sheet (1) Base Material When the PSA sheet according to the present embodiment is the above-described single-sided PSA sheet or double-sided PSA sheet with a base material, the base material constituting the PSA sheet can be laminated with an adhesive layer. The constituent material is not particularly limited as long as it is, and it is usually composed of a film mainly composed of a resin-based material.

Specific examples of the film include ethylene-based copolymer films such as ethylene-vinyl acetate copolymer film, ethylene-(meth)acrylic acid copolymer film, ethylene-(meth)acrylic acid ester copolymer film; Polyethylene films such as density polyethylene (LDPE) film, linear low density polyethylene (LLDPE) film, high density polyethylene (HDPE) film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, ethylene-norbornene copolymer film Polyolefin films such as norbornene resin films; Polyvinyl chloride films such as polyvinyl chloride films and vinyl chloride copolymer films; Polyester films such as polyethylene terephthalate films, polybutylene terephthalate films and polyethylene naphthalate films; Polyurethane films polyimide film; polyamide film; polystyrene film; polycarbonate film; Modified films such as these crosslinked films and ionomer films are also used. The base material may be a film made of one of these, or may be a laminated film in which two or more of these are combined.

The substrate preferably has transparency to active energy rays. When the base material has such transparency, it becomes possible to effectively irradiate the active energy ray to the pressure-sensitive adhesive layer through the base material. As a result, the pressure-sensitive adhesive layer can be cured well, and the pressure-sensitive adhesive sheet can be easily peeled off from the adherend. In addition, when the acid generator (B) is used to generate acid by irradiation with active energy rays, it becomes easier to generate acid effectively, and as a result, the pressure-sensitive adhesive sheet can be easily peeled off from the adherend. Become.

Also, the substrate preferably has heat resistance. In the pressure-sensitive adhesive sheet according to this embodiment, heating the pressure-sensitive adhesive layer promotes the release of the above-described hydrocarbon-based gas. Further, when an acid generator (B) that generates acid by heating is used as the acid generator (B) in the present embodiment, it is necessary to heat the pressure-sensitive adhesive layer also for the generation of the acid. . Therefore, by using a material having heat resistance as the base material, it is possible to suppress deformation of the adhesive sheet even when such heating is performed. In particular, when the adhesive sheet according to the present embodiment is used for dicing a semiconductor wafer or the like, deformation of the adhesive sheet is suppressed, thereby effectively suppressing movement and scattering of cut objects obtained by dicing. becomes possible.

The substrate may contain various additives such as pigments, flame retardants, plasticizers, antistatic agents, lubricants and fillers. Pigments include, for example, titanium dioxide and carbon black. Examples of fillers include organic materials such as melamine resins, inorganic materials such as fumed silica, and metallic materials such as nickel particles. The content of these additives is not particularly limited, but should be within a range that allows the base material to exhibit desired functions and does not lose its smoothness and flexibility.

In addition, in the substrate, for the purpose of improving the adhesion with the layer (adhesive layer, etc.) provided on the surface, primer treatment, oxidation method, roughening method, etc. for providing a primer layer on one side or both sides as desired. Surface treatment can be performed by Examples of the component that constitutes the primer layer in the primer treatment include synthetic resins such as polyester, polyurethane, and polyacrylic resins, and these can be used alone or in combination of two or more. Examples of the oxidation method include corona discharge treatment, chromic acid treatment, flame treatment, hot air treatment, ozone/ultraviolet treatment, and the like. Examples of the roughening method include sandblasting and solvent treatment. These surface treatment methods are appropriately selected according to the type of substrate. As an example, a resin film having a primer layer formed by a primer treatment, particularly a polyethylene terephthalate film is preferably used.

The thickness of the substrate is not limited as long as the pressure-sensitive adhesive sheet can function properly in the desired process. For example, the thickness of the substrate is preferably 20 μm or more, particularly preferably 25 μm or more, and further preferably 50 μm or more. Also, the thickness is preferably 450 μm or less, particularly preferably 400 μm or less, further preferably 350 μm or less.

(2) Adhesive Layer The adhesive layer is formed from the above-described adhesive composition. The thickness of the pressure-sensitive adhesive layer is preferably 1 μm or more, more preferably 5 μm or more, particularly preferably 10 μm or more, further preferably 15 μm or more. The thickness of the pressure-sensitive adhesive layer is preferably 60 μm or less, more preferably 50 μm or less, particularly preferably 40 μm or less, further preferably 30 μm or less. When the thickness of the pressure-sensitive adhesive layer is 1 μm or more, the initial adhesive force to the adherend is sufficient, and the adherend can be more favorably fixed, and the pressure-sensitive adhesive layer is free of hydrocarbon-based When the gas is released, the hydrocarbon-based gas is released in a sufficient amount, and the pressure-sensitive adhesive sheet can be easily peeled off from the adherend by the above-described second effect. In addition, since the thickness of the adhesive layer is 60 μm or less, when the adhesive layer is irradiated with an active energy ray, the adhesive layer can be sufficiently cured easily. It becomes easier to peel off the adhesive sheet from the adherend.

(3) Release Sheet When the adhesive sheet according to the present embodiment includes a release sheet, the release sheet is not limited as long as the release sheet can be easily peeled off from the adhesive layer. Examples of the release sheet include paper substrates such as glassine paper, coated paper, and woodfree paper, laminated paper obtained by laminating these paper substrates with a resin such as polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and the like. and plastic films such as polyolefin films such as polyester films of polypropylene and polyethylene. These release surfaces (surfaces in contact with the pressure-sensitive adhesive layer) are preferably subjected to a release treatment. Release agents used in the release treatment include, for example, silicone-based, fluorine-based, and long-chain alkyl-based release agents.

Although the thickness of the release sheet is not particularly limited, it is usually 20 μm or more and 250 μm or less.

2. Physical properties of pressure-sensitive adhesive sheet The initial pressure-sensitive adhesive strength of the pressure-sensitive adhesive sheet according to the present embodiment (the pressure-sensitive adhesive strength before the above-mentioned first action and second action are caused) is preferably 2 N/25 mm or more, particularly 4 N/ It is preferably 25 mm or more, more preferably 6 N/25 mm or more. Moreover, the initial adhesive strength is preferably 30 N/25 mm or less, particularly preferably 25 N/25 mm or less, further preferably 20 N/25 mm or less. When the adhesive strength is 2 N/25 mm or more, the adherend can be easily held on the adhesive sheet in the process of processing the adherend, and good processing can be easily performed. Further, when the adhesive strength is 30 N/25 mm or less, the adhesive strength after the adhesive layer is cured by irradiation with active energy rays can be easily adjusted within the range described below. The initial adhesive strength basically refers to the adhesive strength measured by the 180° peeling method according to JIS Z0237:2000, and the detailed measuring method is as shown in Examples described later.

Further, in the pressure-sensitive adhesive sheet according to the present embodiment, after curing the pressure-sensitive adhesive layer by irradiating the active energy ray and before heating (that is, the release of the hydrocarbon gas related to the second action described above) The adhesive strength (before formation) is preferably 1 N/25 mm or less, particularly preferably 0.5 N/25 mm or less, and further preferably 0.2 N/25 mm or less. In the pressure-sensitive adhesive sheet according to this embodiment, the pressure-sensitive adhesive layer can be cured by irradiation with active energy rays, so the pressure-sensitive adhesive strength can be reduced to 1 N/25 mm or less. By reducing the adhesive strength to 1 N/25 mm or less, the adhesive sheet can be more easily peeled off from the adherend. Although the lower limit of the adhesive strength is not particularly limited, it is preferably 0.001 N/25 mm or more, particularly preferably 0.005 N/25 mm or more, and further preferably 0.01 N/25 mm or more. is preferred. The adhesive strength is basically the adhesive strength measured by the 180° peeling method according to JIS Z0237:2000, and the detailed measuring method is as shown in Examples described later.

3. Method for Producing Adhesive Sheet The method for producing the adhesive sheet according to the present embodiment is not particularly limited, and the adhesive sheet can be produced in the same manner as for conventional adhesive sheets.

For example, a coating liquid containing a pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer and, optionally, a solvent or a dispersion medium is prepared, and coated on the release surface of the release sheet by a die coater, curtain coater, spray coater, slit coater, The adhesive layer can be formed by applying the coating liquid with a knife coater or the like to form a coating film, and drying the coating film.

The laminate of the pressure-sensitive adhesive layer and the release sheet obtained in this way can be used as it is, or in a state where another release sheet is further laminated on the release agent layer side of the laminate without a substrate. It can be a double-sided adhesive sheet.

In the case of producing a single-sided pressure-sensitive adhesive sheet, the pressure-sensitive adhesive layer side of the laminate of the pressure-sensitive adhesive layer and the release sheet obtained as described above is adhered to one side of the base material. It can be a single-sided pressure-sensitive adhesive sheet comprising a material, a pressure-sensitive adhesive layer, and a release sheet.

As another method for producing a single-sided pressure-sensitive adhesive sheet, a pressure-sensitive adhesive sheet comprising a substrate and a pressure-sensitive adhesive layer is produced by applying the coating solution described above to one side of a substrate and drying the resulting coating film. may

Furthermore, in the case of producing a double-sided pressure-sensitive adhesive sheet with a substrate, two laminates of the pressure-sensitive adhesive layer and the release sheet obtained as described above are prepared, and the pressure-sensitive adhesive layer side of one laminate is By laminating on one surface of the base material and laminating the pressure-sensitive adhesive layer side surface of another laminate on the other surface of the base material, one release sheet, one pressure-sensitive adhesive layer and the base material are combined. A double-sided pressure-sensitive adhesive sheet with a substrate can be obtained in which another pressure-sensitive adhesive layer and another release sheet are laminated in order.

As another method for producing a double-sided pressure-sensitive adhesive sheet with a substrate, the above-described coating solution is applied to both sides of the substrate, and the obtained coating films are dried to form one pressure-sensitive adhesive layer and the substrate. You may manufacture the adhesive sheet provided with another adhesive layer.

The release sheet used for producing the pressure-sensitive adhesive sheet may be peeled off after the production of the pressure-sensitive adhesive sheet, or may protect the pressure-sensitive adhesive layer until the pressure-sensitive adhesive sheet is attached to the adherend. .

In addition, the above coating liquid is not particularly limited in its properties as long as it can be applied, and may contain a component for forming an adhesive layer as a solute or a dispersoid. There is also

In the case where the pressure-sensitive adhesive composition contains the cross-linking agent (D), by changing the drying conditions (temperature, time, etc.) or by separately providing a heat treatment, the (meth)acrylic acid ester It is preferable to allow the cross-linking reaction between the copolymer (A) and the cross-linking agent (D) to proceed to form a cross-linked structure with a desired existence density in the pressure-sensitive adhesive layer. For example, after forming the pressure-sensitive adhesive layer, it is preferable to carry out curing by leaving it in an environment of 23° C. and a relative humidity of 50% for several days.

4. Use of Adhesive Sheet In the adhesive sheet according to the present embodiment, the adhesive layer is formed using the above-described adhesive composition. It can be peeled off from the adherend very easily. Therefore, the pressure-sensitive adhesive sheet according to this embodiment can be suitably used for applications in which the adherend is separated from the pressure-sensitive adhesive sheet after being attached to the adherend. In particular, the adhesive sheet according to the present embodiment is preferably used for processing a predetermined member. Specifically, the adhesive sheet is attached to a workpiece as an adherend, and the workpiece is After processing on the pressure-sensitive adhesive sheet, it is preferably used for separating the obtained processed product from the pressure-sensitive adhesive sheet. Details of such applications will be described later.

The member to be processed as described above is not particularly limited, but includes, for example, a brittle member. Examples of the brittle member include glass, ceramic green sheets, ceramic green sheet laminates, resin films, and thin metal plates. Such a brittle member is likely to crack or collapse when force is applied. In particular, when a brittle member attached to a conventional adhesive sheet is peeled off, the brittle member tends to crack or collapse due to the force applied for the peeling. However, the pressure-sensitive adhesive sheet according to the present embodiment can be peeled off very easily, and for example, it can be peeled off from the adherend by the weight of the pressure-sensitive adhesive sheet itself. It becomes possible to exfoliate while suppressing it. Therefore, it is preferable to use the pressure-sensitive adhesive sheet according to the present embodiment for processing brittle members. In this specification, processing of a member includes forming the member on an adhesive sheet. Therefore, when the member is a ceramic green sheet, the processing of the ceramic green sheet includes not only cutting the already formed ceramic green sheet on the adhesive sheet, but also cutting the ceramic green sheet on the adhesive sheet. Forming a sheet is also included.

Moreover, the adhesive sheet according to the present embodiment is preferably used for semiconductor processing. In particular, it is preferably used for dicing and backside polishing of semiconductor wafers and semiconductor packages. When such dicing is performed, a large number of minute pieces obtained by cutting a semiconductor wafer or a semiconductor package are stacked on the adhesive sheet. These cut pieces are individually picked up from the adhesive sheet. Here, since the pressure-sensitive adhesive sheet according to the present embodiment can be very easily peeled off from the adherend by the above-described first action and second action, the pressure-sensitive adhesive sheet is subjected to the above-described dicing. By using it, it becomes possible to pick up the cut object satisfactorily. In addition, when the adhesive sheet according to the present embodiment is used for back polishing, the adhesive sheet can be peeled off while minimizing the impact on the adherend that has been polished and made very thin. It can effectively suppress the cracking and collapse of the body.

In addition, when the pressure-sensitive adhesive sheet according to the present embodiment is a double-sided pressure-sensitive adhesive sheet, the double-sided pressure-sensitive adhesive sheet is formed by laminating hard adherends together, optionally performing processing or the like, and then separating the adherends from each other. It is preferable to use it for the purpose. Examples of such lamination include lamination of a semiconductor wafer or glass plate with a hard support. Separation of bonded rigid adherends can be extremely difficult when a force is applied to separate the adherends from each other because the adherends do not easily bend even when the force is applied. be. In particular, when the adherends are excessively adhered to each other via the pressure-sensitive adhesive layer, the adherends may be destroyed during separation. However, according to the pressure-sensitive adhesive sheet according to the present embodiment, it is possible to very easily peel off from the adherend by the first action and the second action described above, so the above-mentioned breakage occurs. It is very easy to separate hard adherends from each other without having to separate them. When using the pressure-sensitive adhesive sheet according to the present embodiment for the purposes described above, in order to effectively produce the first action described above, one of the adherends must be exposed to active energy rays. It is preferably permeable.

In addition, the pressure-sensitive adhesive sheet according to the present embodiment includes a base material comprising one pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to the present embodiment and another pressure-sensitive adhesive layer composed of a desired pressure-sensitive adhesive. In the case of a double-sided pressure-sensitive adhesive sheet, it is necessary to achieve both the effect of being able to be very easily peeled off from the adherend by the one pressure-sensitive adhesive layer and the desired effect of the other pressure-sensitive adhesive layer. can also In this way, by combining various pressure-sensitive adhesive layers as other pressure-sensitive adhesive layers, the pressure-sensitive adhesive sheet according to this embodiment can exhibit excellent performance in various applications. Examples of the adhesive that constitutes the other adhesive layer described above include, for example, an active energy ray-curable adhesive, an adhesive that does not easily leave adhesive residue on the adherend, an adhesive that is excellent in heat resistance, and an adhesive that is resistant to solvents. An excellent pressure-sensitive adhesive and the like can be mentioned.

[Manufacturing method of processed product]
A method for manufacturing a processed product according to the present embodiment includes a lamination step of laminating the above-described adhesive sheet on a processed object, a processing step of processing the processed object on the adhesive sheet to obtain a processed product, and the An irradiation step of irradiating the adhesive layer of the adhesive sheet laminated on the workpiece with an active energy ray, and a heating of heating the adhesive layer of the adhesive sheet laminated on the workpiece. and a peeling step of peeling the adhesive sheet that has undergone the irradiation step and the heating step from the workpiece. In the method for manufacturing a workpiece according to this embodiment, the heating process is performed after the irradiation process is completed, or the irradiation process and the heating process are performed simultaneously.

(1) Lamination step In the lamination step described above, the adhesive surface of the adhesive sheet described above is laminated on the object to be processed. When the pressure-sensitive adhesive sheet includes a release sheet, the work piece is laminated on the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer exposed by peeling the release sheet. Here, the workpiece is not particularly limited as long as it can be processed on an adhesive sheet. Examples include semiconductor members such as semiconductor wafers and semiconductor packages, glass, ceramic green sheet laminates, resin films, and thin films. Examples include brittle members such as metal plates, ceramic slurries, coating liquids for forming members such as uncured sealing resins, and the like. When the workpiece already has a predetermined shape, such as the semiconductor wafer described above, lamination is performed by attaching the adhesive surface of the adhesive sheet to the workpiece. In addition, when the workpiece is in a liquid state that does not yet have a predetermined shape, such as the ceramic slurry described above, the workpiece is applied to the adhesive surface of the adhesive sheet to form a coating film. By doing so, lamination is performed. Moreover, when the pressure-sensitive adhesive sheet is a double-sided pressure-sensitive adhesive sheet, the pressure-sensitive adhesive surface of the double-sided pressure-sensitive adhesive sheet opposite to the pressure-sensitive adhesive surface on which the workpiece is laminated may be attached to a support or the like.

(2) Processing Step Following the attaching step, as a processing step, the work is processed on the adhesive sheet to obtain a processed product. Here, when the workpiece is a semiconductor wafer, a semiconductor package, glass, a ceramic green sheet laminate, or the like, the above-described processing includes dicing, back surface polishing, circuit formation, sealing, etc., and the workpiece is , a member of a semiconductor device such as a semiconductor chip, a semiconductor device, a glass chip, and the like are obtained. Moreover, when the workpiece is a ceramic slurry, the coating film obtained by applying the ceramic slurry is dried to obtain a ceramic green sheet as the workpiece.

In the pressure-sensitive adhesive sheet of the present embodiment, since the pressure-sensitive adhesive layer is formed from the above-described pressure-sensitive adhesive composition, before the pressure-sensitive adhesive layer is irradiated with active energy or heated, the object to be processed and the object to be processed Good initial adhesive strength can be exhibited against. Therefore, it is possible to suppress the movement and scattering of the workpiece and the workpiece during the above-described machining, and it is possible to carry out the machining satisfactorily.

(3) Irradiation step and heating step After the processing step, an irradiation step and a heating step are performed. Here, the heating step may be performed after the irradiation step is completed, or the irradiation step and the heating step may be performed simultaneously.

(3-1) Irradiation Step In the irradiation step, the adhesive layer of the adhesive sheet is irradiated with an active energy ray while the workpiece is laminated on the adhesive sheet. Here, it is preferable to irradiate the active energy ray through a member having transparency to the active energy ray. For example, when the pressure-sensitive adhesive sheet is a single-sided pressure-sensitive adhesive sheet provided with a substrate that is permeable to active energy rays, it is preferable to irradiate the pressure-sensitive adhesive layer with the active energy rays through the substrate. Further, when the pressure-sensitive adhesive sheet is a double-sided pressure-sensitive adhesive sheet and one side of the pressure-sensitive adhesive surface is attached to a support having permeability to active energy rays, the pressure-sensitive adhesive layer is activated through the support. Irradiation with energy rays is preferred. Furthermore, in the case where the pressure-sensitive adhesive sheet is either a single-sided pressure-sensitive adhesive sheet or a double-sided pressure-sensitive adhesive sheet, if the processed product laminated in the form of the pressure-sensitive adhesive sheet has transparency to active energy rays, the adhesive is applied through the processed product. The agent layer may be irradiated with active energy rays.

By irradiating the adhesive layer with an active energy ray, a reaction occurs in the active energy ray-reactive group present in the side chain of the (meth)acrylic acid ester copolymer (A) contained in the adhesive layer. proceed. As a result, the pressure-sensitive adhesive layer is cured, and the first effect of reducing the adhesive strength of the pressure-sensitive adhesive layer to the workpiece is produced.

As the acid generator (B), when an acid generator that generates an acid upon irradiation with an active energy ray is used, the acid generator (B) contained in the pressure-sensitive adhesive layer is removed from the acid generator (B) by the irradiation with the active energy ray. acid is produced. The acid promotes a reaction in which a hydrocarbon-based gas is released from the carboxyl precursor group of the (meth)acrylic acid ester copolymer (A) during the heating step.

Examples of the active energy rays include ionizing radiation such as ultraviolet rays and electron beams. Among these, ultraviolet light is preferable because it is relatively easy to introduce irradiation equipment.

When ultraviolet rays are used as the ionizing radiation, it is preferable to use near-ultraviolet rays including ultraviolet rays having a wavelength of about 200 to 380 nm for ease of handling. The amount of ultraviolet light is generally preferably 50 mJ/cm ² or more, particularly preferably 100 mJ/cm ² or more, and more preferably 200 mJ/cm ² or more. Also, the amount of ultraviolet light is usually preferably 2000 mJ/cm ² or less, particularly preferably 1700 mJ/cm ² or less, and more preferably 1400 mJ/cm ² or less. The illuminance of ultraviolet rays is usually preferably 50 mW/cm ² or more, particularly preferably 100 mW/cm ² or more, and more preferably 200 mW/cm ² or more. In addition, the illuminance of ultraviolet rays is usually preferably 500 mW/cm ² or less, particularly preferably 450 mW/cm ² or less, further preferably 400 mW/cm ² or less. There are no particular restrictions on the ultraviolet light source, and for example, high-pressure mercury lamps, metal halide lamps, UV-LEDs and the like are used.

When an electron beam is used as the ionizing radiation, its acceleration voltage is preferably 10 kV or more and 1000 kV or less. Also, the irradiation dose is preferably 0.1 kGy or more and 10 kGy or less. The electron beam source is not particularly limited, and various electron beam accelerators such as Cockroft-Walton type, Vandegraft type, resonant transformer type, insulating core transformer type, linear type, dynamitron type, and high frequency type are used. be able to.

(3-2) Heating Step In the heating step, the pressure-sensitive adhesive layer is heated while the work is laminated on the pressure-sensitive adhesive sheet. In the heating step, the reaction in which the hydrocarbon-based gas is released from the carboxyl precursor group of the (meth)acrylic acid ester copolymer (A) proceeds in the pressure-sensitive adhesive layer by heating. In this reaction, the acid derived from the acid generator (B) acts as a catalyst to promote the reaction. Here, when an acid generator (B) that generates an acid by heating is used, the acid is supplied from the acid generator (B) by heating in the heating step. On the other hand, when an acid generator (B) that generates an acid by irradiation with an active energy ray is used, as described above, the acid generator (B) is irradiated with an acid by irradiation with an active energy ray in the irradiation step. is supplied. The hydrocarbon-based gas released from the pressure-sensitive adhesive layer accumulates at the interface between the pressure-sensitive adhesive layer and the adherend in the pressure-sensitive adhesive sheet, thereby reducing the contact area between the pressure-sensitive adhesive layer and the workpiece. will occur.

Appropriate means such as a hot plate, a hot air dryer, a near-infrared lamp, and a heating roller can be employed as the above-described heating means. As a heating condition, for example, it is preferable to heat at a temperature of 100° C. or more and 250° C. or less for a time of 5 seconds or more and 30 minutes or less.

(4) Peeling Step Following completion of the irradiation step and heating step, the adhesive sheet is peeled from the workpiece. The pressure-sensitive adhesive sheet in the present embodiment has a first action in which the adhesive layer hardens and the adhesive strength decreases, and a second action in which the contact area between the adhesive layer and the workpiece decreases due to the generation of hydrocarbon gas. , the pressure-sensitive adhesive sheet can be very easily peeled off from the workpiece. Therefore, for example, when the workpiece is a semiconductor device (especially a semiconductor chip) or a glass chip, the workpiece can be easily picked up using general-purpose means such as a suction collet. Furthermore, since the adhesive sheet in the present embodiment can be self-peeled without actively peeling off the adhesive sheet, for example, the adhesive sheet is turned upside down. Alternatively, the weight of the adhesive sheet may cause the adhesive sheet to drop from the workpiece, or the weight of the workpiece may cause the workpiece to drop from the adhesive sheet.

Further, when the pressure-sensitive adhesive sheet is a double-sided pressure-sensitive adhesive sheet and one of the pressure-sensitive adhesive surfaces is attached to a support, the pressure-sensitive adhesive sheet is peeled from the support as well as the pressure-sensitive adhesive sheet from the processed product. good too. Here, the order of peeling from the workpiece and peeling from the support is not particularly limited, and they may be performed at the same time. According to the pressure-sensitive adhesive sheet according to this embodiment, it can be very easily peeled off from the support as well as peeled off from the workpiece. The peeling of the adhesive sheet from the support may be performed by removing the adhesive sheet from the support manually or using conventional means, or, as described above, by dropping the adhesive sheet from the support under its own weight. you can go

As described above, in the method for manufacturing a processed product according to the present embodiment, the adhesive sheet can be very easily peeled off from the processed product by irradiation with active energy rays and heating, and thus has excellent performance. It is possible to efficiently manufacture the workpiece.

The embodiments described above are described to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above embodiment is meant to include all design changes and equivalents that fall within the technical scope of the present invention.

EXAMPLES The present invention will be described in more detail with reference to Examples and the like, but the scope of the present invention is not limited to these Examples and the like.

[Example 1]
10 parts by mass of n-butyl acrylate, 35 parts by mass of 2-ethylhexyl acrylate, 45 parts by mass of tert-butyl acrylate, and 10 parts by mass of 2-hydroxyethyl acrylate are copolymerized to form an acrylic copolymer (AP). Obtained. This acrylic copolymer (AP) and methacryloyloxyethyl isocyanate (MOI) as an active energy ray-reactive group-containing compound (AC) were mixed so that the reaction amount of the MOI was 10.7 g per 100 g of the acrylic copolymer ( 80 mol (80 mol %) per 100 mol of 2-hydroxyethyl acrylate units in the acrylic copolymer (AP) were reacted to obtain a (meth)acrylic acid ester copolymer (A). . The mass average molecular weight of the (meth)acrylic acid ester copolymer (A) was measured by the method described below and found to be 500,000.

100 parts by mass of the obtained (meth)acrylic acid ester copolymer (A) (in terms of solid content; hereinafter the same) and 3 parts by mass of 1,8-naphthalimide trifluoromethanesulfonate as the acid generator (B) and 3 parts by mass of 1-hydroxycyclohexylphenyl ketone (manufactured by BASF, product name "Irgacure 184") as a photoinitiator (C), and trimethylolpropane-modified tolylene diisocyanate (Tosoh Corporation) as a cross-linking agent (D). (manufactured by the company, product name "Coronate L") was mixed with 0.5 parts by mass in methyl ethyl ketone as a solvent to obtain a coating liquid of the pressure-sensitive adhesive composition.

The resulting coating liquid was applied onto the release-treated surface of a release sheet (manufactured by Lintec Co., Ltd., product name: "SP-PET381031") in which one main surface of a polyethylene terephthalate film was release-treated with a silicone-based release agent. , and dried by heating at 100° C. for 2 minutes to form a pressure-sensitive adhesive layer having a thickness of 25 μm.

Next, the surface of the pressure-sensitive adhesive layer on the side opposite to the release sheet and a polyester film with an easy-adhesion layer as a base material (manufactured by Toyobo Co., Ltd., product name "Cosmo Shine A4300", thickness: 50 μm) are easily adhered. After laminating the layer side surface, seasoning is performed for 168 hours in an environment of a temperature of 23° C. and a relative humidity of 50% to obtain an adhesive sheet in which a base material, an adhesive layer and a release sheet are laminated in order. rice field.

Here, the mass average molecular weight (Mw) described above is a polystyrene equivalent mass average molecular weight measured under the following conditions using gel permeation chromatography (GPC).
<Measurement conditions>
・ GPC measurement device: HLC-8020 manufactured by Tosoh Corporation
・ Column: "TSK guard column HXL-L", "TSK gel G2500HXL", "TSK gel G2000HXL", "TSK gel G1000HXL" (all manufactured by Tosoh Corporation) are sequentially connected ・Column temperature: 40 ° C.
・Developing solvent: Tetrahydrofuran ・Flow rate: 1.0 mL/min
・Detector: Differential refractometer ・Standard sample: Polystyrene

[Examples 2-3, Comparative Examples 1-3]
Proportion of monomers constituting acrylic copolymer (AP), amount of active energy ray-reactive group-containing compound (AC) used, acid generator (B), photoinitiator (C) and cross-linking agent (D) A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1, except that the content of was changed as shown in Table 1.

[Examples 4 to 7, Comparative Example 4]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1, except that the composition of the monomers constituting the acrylic copolymer (AP) was changed as shown in Table 2.

[Test Example 1] (Measurement of adhesive strength)
The pressure-sensitive adhesive sheets produced in Examples and Comparative Examples were cut to obtain test pieces having a width of 25 mm and a length of 100 mm. The release sheet is peeled off from the test piece, and the exposed adhesive surface is attached to the polished surface of a stainless steel plate (SUS304 polished No. 360) in an environment of 23 ° C. and 50% RH (relative humidity). It was left undisturbed for 24 hours. A sample for measurement was thus obtained.

For this measurement sample, according to JIS Z0237; 2000, a universal tensile tester (manufactured by Orientec Co., Ltd., TENSILON/UTM-4-100) was used to test stainless steel at a peeling speed of 300 mm / min and a peeling angle of 180 °. The adhesive sheet was peeled off from the plate, and the adhesive strength measured at that time was defined as the adhesive strength before UV irradiation (N/25 mm). Results are shown in Tables 1 and 2.

Further, for a measurement sample prepared in the same manner as above, an ultraviolet irradiation device (manufactured by Lintec Co., Ltd., product name "RAD-2000") was used to irradiate the adhesive layer with ultraviolet (UV) light through the base material. (illuminance: 300 mW/cm ² , light intensity: 1200 mJ/cm ² ) to cure the adhesive layer. Then, under the same conditions as above, the adhesive strength of the adhesive sheet was measured, and this was defined as the adhesive strength after UV irradiation (N/25 mm). Results are shown in Tables 1 and 2.

[Test Example 2] (Evaluation of self-peeling property)
For a measurement sample prepared in the same manner as in Test Example 1, the pressure-sensitive adhesive layer is irradiated with ultraviolet (UV) light through the substrate using an ultraviolet irradiation device (manufactured by Lintec Corporation, product name “RAD-2000”). (illuminance: 300 mW/cm ² , light intensity: 1200 mJ/cm ² ) to cure the adhesive layer.

Subsequently, the measurement sample was heated in an oven at 150° C. for 10 minutes, and then left at room temperature. During the heating and standing in the oven, the sample for measurement was handled so that the adhesive sheet side always faced upward.

After the sample for measurement has cooled to room temperature, lift the sample for measurement, and with the stainless steel plate supported, turn the adhesive sheet side and the stainless steel plate side over so that the adhesive sheet side faces down. was made to be Regarding the state of the pressure-sensitive adhesive sheet at that time, the self-peelability of the pressure-sensitive adhesive sheet was evaluated based on the following criteria. Results are shown in Tables 1 and 2.
A: The adhesive sheet fell.
B: Although the adhesive sheet did not fall off, at least one of lifting and peeling due to air bubbles occurred at the interface between the adhesive sheet and the stainless steel plate.
F: The pressure-sensitive adhesive sheet did not drop, and both lifting and peeling due to air bubbles did not occur at the interface between the pressure-sensitive adhesive sheet and the stainless steel plate.

Details of abbreviations and the like in Tables 1 and 2 are as follows.
BA: n-butyl acrylate 2EHA: 2-ethylhexyl acrylate t-BA: tert-butyl acrylate HEA: 2-hydroxyethyl acrylate MOI: 2-methacryloyloxyethyl isocyanate

As can be seen from Tables 1 and 2, the pressure-sensitive adhesive sheets obtained in Examples exhibited excellent self-peeling properties when irradiated with active energy rays and heated, and could be peeled off very easily. there were.

The pressure-sensitive adhesive sheet according to the present invention can be used for processing brittle members, semiconductor members, and the like.

Claims (12)

As monomer units constituting the polymer, it has a (meth)acrylic acid alkyl ester (a1) having an alkyl group with 1 to 12 carbon atoms and a carboxy precursor group that releases a hydrocarbon gas when heated to change to a carboxy group. a (meth)acrylic acid ester copolymer (A) containing a carboxyl precursor group-containing monomer (a2) and having an active energy ray-reactive group in a side chain;
an acid generator (B) that generates an acid by at least one of irradiation with an active energy ray and heating;
containing a photoinitiator (C),
The (meth)acrylic acid ester copolymer (A) contains the carboxy precursor group-containing monomer (a2) as a monomer unit constituting the polymer in a proportion of 35% by mass or more and 75% by mass or less.
A pressure-sensitive adhesive composition characterized by: The (meth)acrylic acid ester copolymer (A) contains a poly(meth)acrylate chain composed of repeating units derived from the carboxy precursor group-containing monomer (a2) and having 10 or more repeating units. The pressure-sensitive adhesive composition according to claim 1, characterized in that it does not 3. The pressure-sensitive adhesive composition according to claim 1 , wherein the (meth)acrylate copolymer (A) contains a hydroxy group-containing monomer (a3) as a monomer unit constituting the polymer. . The carboxyl precursor group-containing monomer (a2) is a (meth)acrylic acid alkyl ester having a structure in which a secondary carbon atom of an alkyl group having a secondary carbon atom and a (meth)acryloyloxy group are bonded; It is characterized by being at least one of (meth)acrylic acid alkyl ester having a structure in which a tertiary carbon atom of an alkyl group having a tertiary carbon atom and a (meth)acryloyloxy group are bonded, and benzyl (meth)acrylate. The pressure-sensitive adhesive composition according to any one of claims 1 to 3 . The carboxyl precursor group-containing monomer (a2) includes sec-butyl (meth)acrylate, isopropyl (meth)acrylate, sec-hexyl (meth)acrylate, sec-octyl (meth)acrylate, sec-nonyl (meth)acrylate, sec -decyl (meth)acrylate, bornyl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, tert-butyl (meth)acrylate, tert-hexyl (meth)acrylate, tert-octyl (meth)acrylate, tert - selected from the group consisting of nonyl (meth)acrylate, tert-decyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, 2-ethyl-2-adamantyl (meth)acrylate, and benzyl (meth)acrylate The pressure-sensitive adhesive composition according to any one of claims 1 to 4 , characterized in that it is at least one kind of 6. The (meth)acrylic acid ester copolymer (A) according to any one of claims 1 to 5, wherein the (meth)acrylic acid ester copolymer (A) contains 2-ethylhexyl acrylate as at least one of the (meth)acrylic acid alkyl esters (a1). 1. The pressure-sensitive adhesive composition according to item 1. A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to any one of claims 1 to 6. 8. The pressure-sensitive adhesive sheet according to claim 7, wherein the pressure-sensitive adhesive layer has a thickness of 1 μm or more and 60 μm or less. 9. The pressure-sensitive adhesive sheet according to claim 7, which is used for processing a brittle member. The pressure-sensitive adhesive sheet according to any one of claims 7 to 9, which is used for semiconductor processing. A lamination step of laminating the pressure-sensitive adhesive sheet according to any one of claims 7 to 10 on a workpiece;
a processing step of processing the workpiece on the adhesive sheet to obtain a workpiece;
an irradiation step of irradiating the adhesive layer of the adhesive sheet laminated on the workpiece with an active energy ray;
A heating step of heating the adhesive layer in the adhesive sheet laminated on the workpiece;
A method for producing a workpiece, comprising a peeling step of peeling the adhesive sheet that has undergone the irradiation step and the heating step from the workpiece,
A method of manufacturing a workpiece, wherein the heating step is performed after the irradiation step is completed, or the irradiation step and the heating step are performed simultaneously. 12. The method of manufacturing a workpiece according to claim 11, wherein the workpiece is a semiconductor device or a member of a semiconductor device.