WO2017149982A1

WO2017149982A1 - Adhesive composition, adhesive sheet, and manufacturing method for said adhesive sheet

Info

Publication number: WO2017149982A1
Application number: PCT/JP2017/001819
Authority: WO
Inventors: 清水　学; まどか中川; 恭平林
Original assignee: 株式会社イーテック
Priority date: 2016-02-29
Filing date: 2017-01-19
Publication date: 2017-09-08
Also published as: JPWO2017149982A1; TW201800535A; CN108633285A; KR20180113199A

Abstract

The purpose of the present invention is to provide: an adhesive composition that, without requiring curing for forming an adhesive layer, has a satisfactorily high adhesive strength before ultraviolent irradiation, a satisfactorily large range of decline in the adhesive strength due to ultraviolent irradiation, sufficiently little adhesive residue, and excellent protrusion-inhibiting properties; an adhesive sheet using the adhesive composition; and a manufacturing method for the adhesive sheet. This adhesive composition contains a photopolymerization initiator and a polymer having a methyl acrylate-derived structural unit, a group containing a polymerizable carbon-carbon double bond, and a urethane group, wherein the proportional content of the structural unit is 1 mass% to 60 mass% relative to all structural units constituting the polymer, the content of urethane groups in the polymer is 0.5 mass% to 2.5 mass%, the gel fraction of the polymer is at least 5 mass%, and the adhesive composition essentially does not contain a thermosetting agent. The polymer preferably has the group including a polymerizable carbon-carbon double bond on a sidechain.

Description

Adhesive composition, adhesive sheet and method for producing the same

The present invention relates to an adhesive composition, an adhesive sheet, and a method for producing the same.

Adhesives are widely used when bonding parts together. One of the uses of the pressure-sensitive adhesive is to temporarily fix the members to each other. For example, in the semiconductor wafer dicing process, the semiconductor wafer is cut in a state where the semiconductor wafer is temporarily fixed to the frame with an adhesive. Then, after the semiconductor wafer has been cut, the semiconductor wafer is removed from the frame. The pressure-sensitive adhesive used for such temporary fixing is required to have a sufficient adhesive force and can be peeled easily and without adhesive residue when temporary fixing is no longer necessary.

Therefore, a technology that uses a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition in temporary fixing, etc., and cures the pressure-sensitive adhesive layer by ultraviolet irradiation when temporary fixing becomes unnecessary, thereby reducing the adhesive strength. Has been proposed (see Japanese Patent Laid-Open No. 2001-240842).

JP 2001-240842 A

However, in the above conventional pressure-sensitive adhesive composition, the adhesive strength before ultraviolet irradiation is insufficient, and the decrease in the adhesive strength due to ultraviolet irradiation is still insufficient. It's not enough. On the other hand, when forming a pressure-sensitive adhesive sheet from a pressure-sensitive adhesive composition, the pressure-sensitive adhesive composition has the ability to reduce the protrusion of the pressure-sensitive adhesive layer when pressure is applied by forming a pressure-sensitive adhesive sheet and rolling. It is also required to have excellent inhibitory properties. Furthermore, in the conventional pressure-sensitive adhesive composition, in order to form a pressure-sensitive adhesive layer, curing after heating and / or standing for several days is necessary after forming the coating film of the pressure-sensitive adhesive composition. In order to simplify the process, there is a demand for an adhesive composition that does not require this curing.

The present invention has been made on the basis of the circumstances as described above, and its purpose is not to require curing for the formation of the pressure-sensitive adhesive layer, and the adhesive strength before UV irradiation is sufficiently high. It is an object of the present invention to provide a pressure-sensitive adhesive composition having a sufficiently large force drop, a small amount of adhesive residue, and excellent extruding suppression, a pressure-sensitive adhesive sheet using this pressure-sensitive adhesive composition, and a method for producing this pressure-sensitive adhesive sheet.

The invention made to solve the above problems includes a structural unit derived from methyl acrylate (hereinafter also referred to as “structural unit (I)”), a polymerizable carbon-carbon double bond-containing group (hereinafter referred to as “double structure”). Bond-containing group (A) ”) and a polymer having a urethane group (hereinafter also referred to as“ [A] polymer ”), a photopolymerization initiator (hereinafter also referred to as“ [B] photopolymerization initiator ”), The content ratio of the structural unit (I) with respect to all the structural units constituting the [A] polymer is 1% by mass or more and 60% by mass or less, and the urethane group content in the [A] polymer is 0%. The pressure-sensitive adhesive composition has a gel fraction of 5% by mass or more and 2.5% by mass or less, a gel fraction of the polymer [A] of 5% by mass or more, and does not substantially contain a thermosetting agent.

Another invention made in order to solve the above-mentioned problems comprises a sheet-like base material and a pressure-sensitive adhesive layer laminated on one surface of the base material, and the pressure-sensitive adhesive layer comprises the pressure-sensitive adhesive composition. It is the adhesive sheet formed from.

Yet another invention made in order to solve the above-mentioned problem is a method for producing the pressure-sensitive adhesive sheet, the step of forming a coating film by coating the pressure-sensitive adhesive composition on one surface of the substrate. It is characterized by providing.

According to the pressure-sensitive adhesive composition and pressure-sensitive adhesive sheet of the present invention, without requiring curing for forming a pressure-sensitive adhesive layer, the pressure-sensitive adhesive force before irradiation with ultraviolet rays is sufficiently high, and the decrease in the pressure-sensitive adhesive force due to ultraviolet irradiation is sufficiently large. Further, the adhesive residue can be sufficiently reduced, and the adhesive layer formed is also excellent in prevention of protrusion. According to the method for producing a pressure-sensitive adhesive sheet of the present invention, the pressure-sensitive adhesive sheet can be produced without requiring curing. Therefore, they can be suitably used in various manufacturing processes such as a semiconductor wafer dicing process.

<Adhesive composition>
The pressure-sensitive adhesive composition contains [A] polymer and [B] photopolymerization initiator. Moreover, the said adhesive composition does not contain a thermosetting agent substantially. The said adhesive composition may contain arbitrary components other than a [A] polymer and a [B] photoinitiator.

The pressure-sensitive adhesive composition has a sufficiently high adhesive strength before ultraviolet irradiation, a sufficiently large decrease in the adhesive strength due to ultraviolet irradiation, a sufficiently small amount of adhesive residue, and an excellent protrusion suppression property. Moreover, the said adhesive composition does not require curing for formation of an adhesive layer. The reason why the pressure-sensitive adhesive composition exhibits the above-described effect by having the above-described configuration is not necessarily clear, but can be inferred as follows, for example. That is, the pressure-sensitive adhesive composition contains the [A] component and the [B] component, and the [A] polymer together with the double bond-containing group (A), the urethane group having the content in the specific range, and the specific range. And the structural unit (I) derived from methyl acrylate having a content ratio of 2 to 5 and further having a gel portion at a ratio equal to or higher than the specific gel fraction. [A] The pressure-sensitive adhesive layer having an appropriate interaction with the adherend and an appropriate strength can be formed when the polymer has a urethane group in the specified range and has a gel fraction equal to or higher than the specified value. it is conceivable that. As a result, the pressure-sensitive adhesive layer does not require a thermosetting agent, has a sufficiently high adhesive strength before ultraviolet irradiation, and suppresses protrusion when pressure is applied by forming a pressure-sensitive adhesive sheet and rolling it. Excellent in properties. Moreover, in the formation of the pressure-sensitive adhesive layer, curing such as heating can be omitted because the pressure-sensitive adhesive composition does not substantially contain a thermosetting agent. On the other hand, the polymer [A] has a structural unit (I) derived from methyl acrylate in a content ratio within the above specific range, but since this structural unit is sterically small, the adhesive force before UV irradiation is more sufficiently exhibited. High, it is possible to sufficiently increase the decrease in adhesive strength due to ultraviolet irradiation, and to sufficiently reduce the adhesive residue. Hereinafter, each component will be described.

<[A] polymer>
[A] The polymer is a polymer having a structural unit (I), a double bond-containing group (A), and a urethane group. [A] In the polymer, the content ratio of the urethane group, the content ratio of the structural unit (I), and the gel fraction are within the specific ranges.

[A] The polymer is a structural unit derived from a (meth) acrylic acid alkyl ester containing an alkyl group having 4 to 10 carbon atoms in addition to the structural unit (I) as a structural unit (hereinafter referred to as “structural unit (II)”). Also a structural unit containing a hydroxy group (hereinafter also referred to as “structural unit (III)”), a structural unit containing an epoxy group (hereinafter also referred to as “structural unit (IV)”) and / or a plurality of polymerizable groups. It is preferable to further have a structural unit derived from a compound having a carbon-carbon double bond (hereinafter also referred to as “structural unit (V)”), and other structural units other than the structural units (I) to (V) Furthermore, you may have. The double bond-containing group (A) and the urethane group may be contained in the structural units (II) to (V) and other structural units. Hereinafter, a double bond containing group (A), a urethane group, and each structural unit are demonstrated.

[Double bond-containing group (A)]
The double bond-containing group (A) is a group containing a polymerizable carbon-carbon double bond. A polymerizable carbon-carbon double bond means an ethylenic carbon-carbon double bond.

The double bond-containing group (A) is not particularly limited as long as it contains a polymerizable carbon-carbon double bond, and examples thereof include a (meth) acryloyl group, a vinyl group, an allyl group, and a styryl group. Among these, a (meth) acryloyl group is preferable from the viewpoints of excellent polymerizability and a sufficiently large decrease in the adhesive strength after ultraviolet irradiation.

[A] The polymer may have a double bond-containing group (A) in any of the main chain, the side chain, and the terminal. From the viewpoint of sufficiently increasing the decrease in the adhesive strength after irradiation, it is preferable to have the side chain.

As a method for obtaining the polymer [A] in which the double bond-containing group (A) is introduced into the side chain, for example, a precursor polymer having at least one of a hydroxy group and an epoxy group is prepared, and (1) a precursor polymer A method of reacting an isocyanate group of a compound having an isocyanate group and a double bond-containing group (A) with the hydroxy group of (2), (2) a carboxy group and a double bond-containing group (A) to the epoxy group of the precursor polymer (3) a method of reacting a carboxy group of a compound having carboxy group of a compound having a carboxy group and a double bond-containing group (A) with a hydroxy group of a precursor polymer, The method etc. which use two or more of (3) together are mentioned. In the case of (1), the double bond-containing group (A) is introduced into the side chain of the precursor polymer and a urethane group is formed.

Examples of the compound having an isocyanate group and a double bond-containing group (A) include (meth) acryloylalkyl isocyanates such as 2- (meth) acryloyloxyethyl isocyanate and 2- (meth) acryloyloxypropyl isocyanate; 2- (2 Examples include 2- (2- (meth) acryloyloxyalkyloxy) alkyl isocyanate such as-(meth) acryloyloxyethyloxy) ethyl isocyanate and 2- (2- (meth) acryloyloxypropyloxy) propyl isocyanate. Examples of commercially available 2- (meth) acryloyloxyethyl isocyanate include “Karenz AOI” and “Karenz MOI” manufactured by Showa Denko KK. Examples of commercially available 2- (2-methacryloyloxyethyloxy) ethyl isocyanate include “Karenz MOIEG” from Showa Denko.

Examples of the compound having a carboxy group and a double bond-containing group (A) include (meth) acrylic acid; carboxyalkyl (meth) acrylates such as carboxymethyl (meth) acrylate and carboxyethyl (meth) acrylate.

As another method for obtaining a polymer [A] having a double bond-containing group (A) introduced in the side chain, for example, a precursor polymer having at least one of a hydroxy group and an epoxy group is prepared, and (4 ) One of the isocyanate groups of the polyisocyanate compound is reacted with the hydroxy group of the precursor polymer, and the other isocyanate group of the polyisocyanate compound has a hydroxyl group and a double bond-containing group (A). (5) reacting one of the carboxy groups of the polycarboxylic acid compound with the epoxy group of the precursor polymer, and reacting the other carboxy group of the polycarboxylic acid compound with an epoxy group and a double bond A method of reacting an epoxy group of a compound having a containing group (A), (6) a hydroxy group of a precursor polymer One of the carboxy groups of the polycarboxylic acid compound is bonded by dehydration condensation, and the hydroxy group of the compound having the hydroxy group and the double bond-containing group (A) is dehydrated and condensed to the other carboxy group of the polycarboxylic acid compound. Examples include a method of reacting, a method of using a plurality of these (4) to (6) in combination. In the case of (4), the double bond-containing group (A) is introduced into the side chain of the precursor polymer, and a plurality of urethane groups are formed.

Examples of the polyisocyanate compound include methylene diphenyl diisocyanate (MDI), tolylene diisocyanate (TDI), isophorone diisocyanate (IPDI), and the like.

Examples of the polycarboxylic acid compound include aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, and adipic acid, and aromatic dicarboxylic acids such as phthalic acid and terephthalic acid.

[A] The lower limit of the content of the double bond-containing group (A) in the polymer is preferably 0.5% by mass, more preferably 0.6% by mass, still more preferably 0.8% by mass. 0% by mass is particularly preferred. As an upper limit of the said content rate, 10 mass% is preferable, 5 mass% is more preferable, 4 mass% is further more preferable, and 3 mass% is especially preferable. By making the content rate of a double bond containing group (A) into the said range, the fall width of the adhesive force by ultraviolet irradiation can be enlarged more fully, and adhesive residue can be reduced more fully. [A] The content (% by mass) of the double bond-containing group (A) in the polymer is obtained by dividing the total mass of each atom constituting the double bond-containing group (A) by the total mass of the polymer. Can be sought.

[Urethane group]
The urethane group is a group represented by —NH—C (═O) —O—. [A] Since the polymer has a urethane group, the strength of the formed pressure-sensitive adhesive layer can be increased by hydrogen bonding between the urethane groups.

As described above, the urethane group can be formed by, for example, reacting a hydroxyl group of the precursor polymer with a compound having an isocyanate group. That is, when the double bond-containing group (A) is introduced into the side chain of the precursor polymer using the method (1) or (4) described above, a urethane group is formed in the side chain of the polymer. As a compound which has an isocyanate group, the compound etc. which have the above-mentioned isocyanate group and a double bond containing group (A) are mentioned, for example. With this compound having an isocyanate group and a double bond-containing group (A), both the urethane group and the double bond-containing group (A) can be introduced into the precursor polymer. Moreover, a urethane group can be introduce | transduced by using the monomer which has a urethane group as a monomer used for the polymerization reaction which synthesizes [A] polymer. Examples of the monomer having a urethane group include (meth) acrylate having a urethane group such as methoxycarbonylaminoethyl (meth) acrylate and cyclohexyloxycarbonylaminopropyl (meth) acrylate.

[A] The lower limit of the urethane group content in the polymer is 0.5% by mass, preferably 0.7% by mass, more preferably 0.9% by mass, and even more preferably 1.0% by mass. The upper limit of the content is 2.5% by mass, preferably 2.2% by mass, more preferably 1.8% by mass, and further preferably 1.5% by mass. By setting the content of the urethane group in the above range, the adhesive strength before ultraviolet irradiation can be made sufficiently higher. If the content of the urethane group is less than the above lower limit, it is considered that the strength of the pressure-sensitive adhesive layer to be formed is lowered, and there is a possibility that protrusion occurs when the pressure-sensitive adhesive sheet is formed and rolled. When the urethane group content exceeds the above upper limit, adhesiveness may be reduced due to a decrease in adhesion to the substrate in the production of the pressure-sensitive adhesive sheet. [A] The content (% by mass) of the urethane group in the polymer can be obtained by dividing the “total mass of each atom constituting the urethane group” by the “total mass of the polymer”.

[Structural unit (I)]
The structural unit (I) is a structural unit derived from methyl acrylate. The structural unit (I) has a structure represented by —CH ₂ —CH (COOCH ₃ ) —.

As a minimum of the content rate of structural unit (I), it is 1 mass% with respect to all the structural units which comprise a [A] polymer, 5 mass% is preferable, 10 mass% is more preferable, and 20 mass% is More preferred is 30% by mass. As an upper limit of the said content rate, it is 60 mass%, 55 mass% is preferable, 50 mass% is more preferable, 45 mass% is further more preferable, 40 mass% is especially preferable. By making the content ratio of the structural unit (I) in the above range, the adhesive strength before ultraviolet irradiation can be made sufficiently higher, and the decrease in adhesive strength due to ultraviolet irradiation can be made sufficiently larger, In addition, the adhesive residue can be sufficiently reduced. In addition, by setting the content ratio of the structural unit (I) in the above range, even when there is a step on the surface of the adherend, it is possible to exhibit sufficient adhesive force, that is, excellent embedding property. If the content ratio of the structural unit (I) is less than the above lower limit, it is considered that the strength of the pressure-sensitive adhesive layer is reduced, and as a result, the adhesive strength before ultraviolet irradiation is reduced and adhesive residue tends to be generated. When the content ratio of the structural unit (I) exceeds the above upper limit, it is considered that the effect that the [A] polymer aggregates due to crosslinking when the pressure-sensitive adhesive layer is irradiated with ultraviolet rays is reduced, and as a result, adhesive residue tends to occur. is there.

[Structural unit (II)]
The structural unit (II) is a structural unit derived from a (meth) acrylic acid alkyl ester containing an alkyl group having 4 to 10 carbon atoms. The said adhesive composition can raise the intensity | strength of an adhesive layer more because [A] polymer has structural unit (II), As a result, the adhesive force before ultraviolet irradiation can be raised more.

Examples of the alkyl group having 4 to 10 carbon atoms include an n-butyl group, an n-pentyl group, an n-hexyl group, an n-octyl group, a 2-ethylhexyl group, and an n-decyl group. Of these, n-butyl group and 2-ethylhexyl group are preferable.

Monomers that give structural unit (II) include n-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, n-octyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. And alkyl (meth) acrylates such as n-decyl (meth) acrylate. Among these, alkyl acrylate is preferable, and n-butyl acrylate and 2-ethylhexyl acrylate are more preferable.

[A] When the polymer has the structural unit (II), the lower limit of the content ratio of the structural unit (II) is preferably 35% by mass, more preferably 40% by mass, further preferably 45% by mass, and 50% by mass. Is particularly preferred. As an upper limit of the said content rate, 75 mass% is preferable, 70 mass% is more preferable, 65 mass% is further more preferable, 60 mass% is especially preferable. By making the content rate of structural unit (II) into the said range, the intensity | strength of an adhesive layer can further be raised and as a result, the adhesive force before ultraviolet irradiation can further be raised.

[Structural unit (III)]
The structural unit (III) is a structural unit containing a hydroxy group. [A] When the polymer has the structural unit (III), the adhesive force of the pressure-sensitive adhesive layer before ultraviolet irradiation is further improved and the water resistance is improved.

Examples of the hydroxy group include alcoholic hydroxy groups and phenolic hydroxy groups. Among these, alcoholic hydroxy groups are preferable from the viewpoint of further improving the adhesive strength before ultraviolet irradiation.

Examples of monomers that give structural unit (III) include hydroxyalkyl (meth) acrylates such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and hydroxybutyl (meth) acrylate; hydroxyphenyl (meth) acrylate and hydroxynaphthyl And hydroxyaryl (meth) acrylates such as (meth) acrylates. Among these, hydroxyalkyl (meth) acrylate is preferable, hydroxyalkyl acrylate is more preferable, and hydroxyethyl acrylate is more preferable.

[A] When the polymer has the structural unit (III), the lower limit of the content ratio of the structural unit (III) is preferably 1% by mass, more preferably 2% by mass, further preferably 3% by mass, and 4% by mass. Is particularly preferred. As an upper limit of the said content rate, 30 mass% is preferable, 25 mass% is more preferable, 20 mass% is further more preferable, 15 mass% is especially preferable, 7 mass% is further especially preferable.

[Structural unit (IV)]
The structural unit (IV) is a structural unit containing an epoxy group. [A] When the polymer has the structural unit (IV), the adhesive force of the pressure-sensitive adhesive layer before ultraviolet irradiation is further improved, and the adhesion to the substrate and the like is improved.

Examples of the monomer that gives the structural unit (IV) include oxiranyl groups such as glycidyl (meth) acrylate, oxiranylethyl (meth) acrylate, oxiranylpropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate glycidyl ether. And (meth) acrylates containing oxetanyl groups such as oxetanylmethyl (meth) acrylate, oxetanylethyl (meth) acrylate, oxetanylpropyl (meth) acrylate, and the like. Of these, (meth) acrylates containing an oxiranyl group are preferred, and glycidyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate glycidyl ether are more preferred.

[A] When the polymer has the structural unit (IV), the lower limit of the content ratio of the structural unit (IV) is preferably 1% by mass, more preferably 3% by mass, further preferably 5% by mass, and 7% by mass. Is particularly preferred. As an upper limit of the said content rate, 30 mass% is preferable, 25 mass% is more preferable, 20 mass% is further more preferable, 15 mass% is especially preferable.

[Structural unit (V)]
The structural unit (V) is a structural unit derived from a compound having a plurality of polymerizable carbon-carbon double bonds. In the pressure-sensitive adhesive composition, since the [A] polymer has the structural unit (V), the pressure-sensitive adhesive layer is prevented from protruding when pressure is applied by forming a pressure-sensitive adhesive sheet and rolling it.

The polymerizable carbon-carbon double bond constitutes, for example, a (meth) acryloyl group, a vinyl group, an allyl group, a styryl group, and the like. Among these, from the viewpoint of ease of polymerization, a polymerizable carbon-carbon double bond constituting a (meth) acryloyl group is preferred, and a polymerizable carbon-carbon double bond constituting an acryloyl group is more preferred.

Examples of the monomer that gives the structural unit (V) include alkanes such as 1,6-hexanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, and 1,3-propanediol di (meth) acrylate. Diol di (meth) acrylate; a compound having two polymerizable carbon-carbon double bonds such as diallyl ether, dialkenyl ether such as dibutenyl ether, etc.
Examples thereof include compounds having three or more polymerizable carbon-carbon double bonds such as triethanolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate and pentaerythritol tetra (meth) acrylate. Among these, compounds having two polymerizable carbon-carbon double bonds are preferable, alkanediol di (meth) acrylate is more preferable, and 1,6-hexanediol di (meth) acrylate is more preferable.

[A] When a polymer has a structural unit (V), as a minimum of the content rate of a structural unit (V), 0.005 mass% is preferable, 0.05 mass% is more preferable, 0.1 mass% is Further preferred is 0.2% by mass. As an upper limit of the said content rate, 5 mass% is preferable, 1 mass% is more preferable, 0.8 mass% is further more preferable, 0.6 mass% is especially preferable. By making the content rate of a structural unit (V) into the said range, the protrusion of the adhesive layer at the time of applying pressure by forming an adhesive sheet and making it roll is suppressed more.

[Other structural units]
[A] The polymer may have other structural units other than the structural units (I) to (V). Examples of other structural units include structural units derived from styrene compounds. Examples of the styrene compound include styrene, α-methylstyrene, o-, m- or p-methylstyrene, o-, m- or p-hydroxystyrene. As an upper limit of the content rate of another structural unit, 30 mass% is preferable with respect to all the structural units which comprise a [A] polymer, 20 mass% is more preferable, and 10 mass% is further more preferable.

<[A] Polymer Synthesis Method>
[A] In the method for synthesizing the polymer, for example, monomers that give structural units (I) to (V) and other structural units are used using a radical polymerization initiator such as azobisisobutyronitrile (AIBN). A precursor polymer is obtained by polymerization in a solvent such as ethyl acetate. Next, a compound having a double bond-containing group (A), an isocyanate group, a carboxy group, etc., in the hydroxy group, epoxy group, etc. of this precursor polymer, ethyl acetate, etc. in the presence of a reaction catalyst such as dibutyltin dilaurate In the solvent. Thereby, since a double bond containing group (A) is introduce | transduced into a precursor polymer, [A] polymer is compoundable.

The precursor polymer preferably has a structural unit containing a hydroxy group and / or a structural unit containing an epoxy group. By having such a structural unit, the double bond-containing group (A) can be easily introduced into the precursor polymer. Examples of the monomer that gives a structural unit containing a hydroxy group and / or a structural unit containing an epoxy group include compounds similar to those exemplified as the monomer giving the structural unit (III) and the structural unit (IV). Can be mentioned.

The lower limit of the reaction temperature in the polymerization of the precursor polymer is preferably 40 ° C, more preferably 60 ° C. As an upper limit of the said reaction temperature, 150 degreeC is preferable and 100 degreeC is more preferable. As a minimum of reaction time in superposition | polymerization, 1 hour is preferable and 4 hours is more preferable. The upper limit of the reaction time is preferably 48 hours, more preferably 24 hours.

The lower limit of the reaction temperature for the introduction reaction of the double bond-containing group (A) is preferably 20 ° C, more preferably 30 ° C. As an upper limit of the said reaction temperature, 100 degreeC is preferable and 60 degreeC is more preferable. As a minimum of reaction time in introduction reaction of a double bond content group (A), 1 hour is preferred and 3 hours is more preferred. The upper limit of the reaction time is preferably 20 hours, and more preferably 8 hours.

[A] The lower limit of the weight average molecular weight (Mw) in terms of polystyrene by gel permeation chromatography (GPC) of the polymer is preferably 50,000, more preferably 200,000, still more preferably 350,000, and particularly preferably 450,000. The upper limit of the Mw is preferably 1 million, more preferably 900,000, still more preferably 800,000, and particularly preferably 700,000. The said adhesive composition can make adhesive force before ultraviolet irradiation more fully high by making Mw of [A] polymer into the said range.

[A] The lower limit of the ratio (Mw / Mn) of Mw to the number average molecular weight (Mn) in terms of polystyrene by GPC of the polymer is usually 1 and preferably 1.1. As an upper limit of the ratio, 5 is preferable, 3 is more preferable, 2 is more preferable, and 1.7 is particularly preferable.

In this specification, each condition of GPC used for measuring Mw and Mn of [A] polymer is as follows.
GPC column: For example, two “TSKgel Multipore H _XL- M” manufactured by Tosoh Corporation Column temperature: 40 ° C.
Elution solvent: Tetrahydrofuran (Wako Pure Chemical Industries, Ltd.)
Flow rate: 1.0 mL / min Sample concentration: 0.05% by mass
Sample injection volume: 100 μL
Detector: Differential refractometer Standard material: Monodisperse polystyrene

[A] The lower limit of the glass transition temperature (Tg) of the polymer is preferably −100 ° C., more preferably −80 ° C., further preferably −60 ° C., and particularly preferably −40 ° C. The upper limit of the Tg is preferably 20 ° C., more preferably 0 ° C., further preferably −10 ° C., and particularly preferably −15 ° C. The said adhesive composition can improve the adhesive force before ultraviolet irradiation more by making Tg of [A] polymer into the said range.

The Tg of the [A] polymer in the present specification is increased by using a differential scanning calorimeter (for example, “MDSCQ200 type” manufactured by TA Instruments) for the dried film of the [A] polymer in a nitrogen atmosphere. It is a value measured under conditions of a temperature rate of 20 ° C./min and a sample amount of 20 mg.

(Gel fraction)
[A] The lower limit of the gel fraction of the polymer is 5% by mass, preferably 10% by mass, more preferably 14% by mass, and still more preferably 18% by mass. As an upper limit of the said gel fraction, 40 mass% is preferable, 34 mass% is more preferable, and 28 mass% is further more preferable. [A] By setting the gel fraction of the polymer in the above range, the strength of the pressure-sensitive adhesive layer to be formed can be further increased, and as a result, the adhesive force before ultraviolet irradiation can be sufficiently increased. [A] If the gel fraction of the polymer is less than the above lower limit, it is considered that the strength of the pressure-sensitive adhesive layer to be formed is lowered, and there is a possibility that the pressure-sensitive adhesive protrudes when the pressure-sensitive adhesive sheet is formed and rolled. is there.

[A] The gel fraction of the polymer refers to the proportion of the insoluble toluene in the [A] polymer. Specifically, a sample containing [A] polymer is added to toluene and stirred, and the filtrate obtained by filtering through a filter with a pore size of 0.10 μm is concentrated, and the obtained mass W _{1 of the} solid content, It is a value (mass%) calculated from (W ₂ −W ₁ ) × 100 / W ₂ from the mass W ₂ of the [A] polymer in the sample.

<[B] Photopolymerization initiator>
[B] The photopolymerization initiator is a component capable of initiating a polymerization reaction by irradiation with ultraviolet rays. The pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition contains [B] a photopolymerization initiator, so that the double bond-containing groups (A) included in the [A] polymer when irradiated with ultraviolet irradiation It is cured by the polymerization reaction. As a result, the pressure-sensitive adhesive layer has a reduced interaction with the adherend and a reduced adhesive strength.

[B] As the photopolymerization initiator, for example, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenyl Acetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl ] -2-Morpholino-propan-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4′-die Aminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoate, oligo [2-hydroxy-2-methyl-1 [4- (1-methylvinyl) phenyl] propanone], 2, Examples include 4,6-trimethylbenzoyl-diphenyl-phosphine oxide. Of these, 1-hydroxycyclohexyl phenyl ketone is preferred.

[B] Commercially available photopolymerization initiators include, for example, “Irgacure 184”, “651”, “2959”, “127”, “819”, “784” and “754” of BASF. , “Same 500”, “Same 250”, “Same 270”, “Same 907”, “Same 369”, “Same 379EG”, “Same OXE 01”, “Same OXE 02”, “Lucirin TPO”, “Darocure” 1173 "," same MBF ", and the like.

[B] The lower limit of the content of the photopolymerization initiator is preferably 0.1 parts by weight, more preferably 0.5 parts by weight, and even more preferably 1 part by weight with respect to 100 parts by weight of the polymer [A]. 2 parts by mass is particularly preferred. As an upper limit of the said content, 20 mass parts is preferable, 10 mass parts is more preferable, 8 mass parts is further more preferable, 6 mass parts is especially preferable. [B] By setting the content of the photopolymerization initiator in the above range, the polymerization reaction between the double bond-containing groups (A) by ultraviolet irradiation proceeds more effectively, and as a result, the adhesive strength after ultraviolet irradiation. Is further sufficiently large, and the adhesive residue is more sufficiently reduced.

<Optional component>
The pressure-sensitive adhesive composition includes, as an optional component, for example, an antioxidant, an anti-aging agent, an ultraviolet absorber, a light stabilizer, an antifoaming agent, a leveling agent, an antistatic agent, a surfactant, a storage stabilizer, and a thermal polymerization prohibition. An agent, a plasticizer, a wettability improver, an adhesion promoter, a tackifier (tacky fire), a solvent, and the like may be contained. However, it is preferable that the pressure-sensitive adhesive composition does not substantially contain a polyfunctional monomer (a compound having a plurality of polymerizable carbon-carbon double bonds).

Examples of the polyfunctional monomer include dipentaerythritol hexaacrylate, dipentaerythritol pentaacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, and the like.

Here, “substantially free of polyfunctional monomer” means that the content of the polyfunctional monomer is, for example, 10 parts by mass or less, preferably 5 parts by mass or less, more preferably 2 parts per 100 parts by mass of the polymer. It means less than mass parts, particularly preferably 0 mass parts.

Examples of the antioxidant include butylhydroxytoluene (BHT), butylhydroxyanisole (BHA), pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], thiodiethylenebis [ 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, and the like. Examples of commercially available antioxidants include “Irganox 1035”, “1010”, “1076”, “1135”, and “1520L” of BASF.

Examples of the antiaging agent include phenolic antiaging agent, allylamine antiaging agent, and ketone amine antiaging agent. Commercially available anti-aging agents include, for example, “Antigen W”, “S”, “P”, “3C”, “6C”, “RD-G”, “FR” from Sumitomo Chemical Co., Ltd. , “Same AW” and the like.

Examples of UV absorbers include benzotriazole UV absorbers and triazine UV absorbers. Commercially available UV absorbers include, for example, “TINUVIN P”, “234”, “320”, “326”, “327”, “328”, “213”, “ 400, Sumitomo Chemical's “Sumisorb 110”, “130”, “140”, “220”, “250”, “300”, “320”, “340”, “350” ", 400", and the like.

Examples of the antifoaming agent include a silicone-based antifoaming agent, a fluorine atom-containing antifoaming agent, and an antifoaming agent containing an organic copolymer containing no silicon atom or fluorine atom. Examples of commercially available antifoaming agents include silicone-based antifoaming agents such as “Same AC-901”, “Same AC-950”, “Same AC-1140”, “Same AO-3”, “ AO-4OH, Toray Dow Corning Silicone's “FS1265”, “SH200”, “SH5500”, “SC5540”, “SC5570”, “F-1”, “SD5590”, etc. As foaming agents, DIC's “Megafac F-142D”, “F-144D”, “F-178K”, “F-179”, “F-815”, etc. are silicon atoms and fluorine atoms. As an antifoaming agent containing an organic copolymer that does not contain any of the above, Kyoeisha Chemical Co., Ltd. “Floren AC-202”, “AC-300”, “AC-303”, “AC-326F”, “AC -900 " "The AC-1190", and the like, "the AC-2000".

Examples of the leveling agent include “Polyflow No. 7”, “No. 38”, “No. 50”, “No. 75”, “No. 77”, and “No. 90” of Kyoeisha Chemical Co., Ltd. ”,“ No. 95 ”,“ No. 300 ”,“ No. 460 ”,“ ATF ”,“ KL-245 ”, and the like.

Examples of the adhesion-imparting agent include thiol compounds having an alkoxysilyl group and phosphate ester compounds. These compounds have the effect of improving the adhesion to the metal surface.

Examples of the thiol compound having an alkoxysilyl group include mercaptoalkyl-mono, di- or tri-methoxysilane such as γ-mercaptopropyltrimethoxysilane, γ-mercaptopropylmethylmonomethoxysilane, and γ-mercaptopropylmethyldimethoxysilane. Can be mentioned. Commercially available products include “SH6062” and “AY43-062” from Toray Dow Corning Silicone, “Syra Ace S810” from Chisso, “KBM803”, “KBM403” and “KBE5103” from Shin-Etsu Chemical Co., Ltd. Can be mentioned.

Examples of the phosphoric acid ester compound include mono [2- (meth) acryloyloxyethyl] phosphate, mono [2- (meth) acryloyloxyethyl] diphenyl phosphate, mono [2- (meth) acryloyloxypropyl] phosphate, bis [ 2- (meth) acryloyloxyethyl] phosphate, bis [2- (meth) acryloyloxypropyl] phosphate, tris [2- (meth) acryloyloxyethyl] phosphate, and the like. Examples of commercially available products include “Light Ester P-1M”, “P-2M”, “Light Acrylate P-1A” and “P-2A” manufactured by Kyoeisha Chemical Co., Ltd., “KAYAMER PM-2” manufactured by Nippon Kayaku Co., Ltd. And “PM-21”.

Examples of the tackifier include alicyclic saturated hydrocarbon resin, rosin ester series, terpene phenol series, C5 or C9 petroleum resin, and the like. Examples of commercially available products include “Arcon P-70”, “P-90”, “P-100”, “M-90”, “M-100”, “M-M” of Arakawa Chemical Industries, Ltd. 135 ”,“ Alastor 700 ”,“ Same KE-359 ”,“ Tamanol 521 ”,“ Superester A-75 ”,“ Same A-115 ”and the like.

Examples of the solvent include aromatic solvents such as toluene and xylene;
Ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, 2-methyl-5-hexanone;
Ester solvents such as ethyl acetate and butyl acetate;
Halogen solvents such as methyl chloride, dichloromethane, dichloroethane;
Glycol ether solvents such as ethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol mono n-propyl ether, propylene glycol;
Examples include glycol ether carboxylate solvents such as propylene glycol monomethyl ether acetate.

The amount of the optional component used can be appropriately selected within a range that does not impair the effect of the pressure-sensitive adhesive composition of the present invention.

The lower limit of the viscosity of the pressure-sensitive adhesive composition at 25 ° C. is preferably 100 mPa · s, more preferably 200 mPa · s, still more preferably 500 mPa · s, and particularly preferably 1,000 mPa · s. The upper limit of the viscosity is preferably 5,000 mPa · s, more preferably 3,000 mPa · s, further preferably 2,500 mPa · s, and particularly preferably 2,000. By making the viscosity of the said adhesive composition into the said range, it can coat easily and as a result, an adhesive layer can be formed favorable. The viscosity is a value measured using a BM viscometer under the condition of a rotation speed of 30 rpm.

The pressure-sensitive adhesive composition does not substantially contain a thermosetting agent. The thermosetting agent means a compound capable of forming a crosslinked structure in the [A] polymer by heating. In the pressure-sensitive adhesive composition, since the [A] polymer has the above-described configuration, the formed pressure-sensitive adhesive layer has a gel structure, so that the shape retention is excellent, and as a result, the protrusion suppression property is excellent. Therefore, the said adhesive composition does not require a thermosetting agent. Since the pressure-sensitive adhesive composition does not substantially contain a thermosetting agent, when the pressure-sensitive adhesive layer is formed, heating after forming the coating and / or curing for several days is not required, and the time is shortened. In addition, the manufacturing process can be simplified.

Examples of the thermosetting agent include polyfunctional isocyanate compounds and polyfunctional epoxy compounds. Examples of the thermosetting agent include melamine compounds, metal salt compounds, metal chelate compounds, amino resin compounds, peroxides, and the like.

Examples of the polyfunctional isocyanate compound include diisocyanate compounds such as toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and hexamethylene diisocyanate (HDI), polyisocyanate compounds that are dimers or multimers of the above diisocyanate compounds, The compound etc. which modified the isocyanate compound are mentioned. As a commercial item of a polyfunctional isocyanate compound, "Coronate L" etc. of Tosoh Corporation is mentioned, for example.

Examples of the polyfunctional epoxy compound include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, dibromo Neopentyl glycol diglycidyl ether, o-phthalic acid diglycidyl ester, glycerin polyglycidyl ether, trimethylolpropane polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, N, N, N ′ , N′-tetraglycidyl-m-xylylenediamine, N, N, N ′, N ″, N '- penta glycidyl diethylenetriamine, N, N, N', N'- tetraglycidyl ethylenediamine, and the like. Examples of commercially available polyfunctional epoxy compounds include “NADECOL EX-313”, “EX-412”, “EX-521”, and “EX-614B” manufactured by Nagase Chemtech.

Here, “the adhesive composition does not substantially contain a thermosetting agent” means that the content of the thermosetting agent with respect to 100 parts by mass of the polymer [A] is, for example, 0.1 parts by mass or less, preferably 0.8. This means that it is 05 parts by mass or less, more preferably 0.02 parts by mass or less, and particularly preferably 0 parts by mass.

<Method for preparing pressure-sensitive adhesive composition>
The pressure-sensitive adhesive composition can be prepared, for example, by mixing [A] polymer, [B] photopolymerization initiator, and optional components contained as necessary at a predetermined ratio.

<Adhesive sheet>
The pressure-sensitive adhesive sheet of the present invention includes a sheet-like base material and a pressure-sensitive adhesive layer laminated on one surface of the base material, and the pressure-sensitive adhesive layer is formed from the pressure-sensitive adhesive composition. Since the pressure-sensitive adhesive sheet is provided with a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition described above, the pressure-sensitive adhesive force before ultraviolet irradiation is sufficiently high, the decrease in the pressure-sensitive adhesive force due to ultraviolet irradiation is sufficiently large, and the adhesive residue is removed. It can be sufficiently reduced and has excellent embeddability. Therefore, the said adhesive sheet can be adhere | attached with high adhesive force with respect to various adherends, and can be easily peeled from an adherend. "Sheet" means a sheet-like thing, and is a concept including a tape and a film, for example.

The pressure-sensitive adhesive sheet is, for example, a dicing tape for fixing a semiconductor wafer to a frame or the like when performing a dicing process of a semiconductor wafer, or a temporary fixing tape for temporarily fixing circuit elements or the like in a manufacturing process of an electronic component or the like. In addition, it can be suitably used as a transport tape used when transporting circuit elements or the like in a semiconductor wafer manufacturing process. In addition to using the pressure-sensitive adhesive sheet as a tape as described above, the pressure-sensitive adhesive sheet can also be used as a film with a metal foil used in the production of a multilayer wiring board or a transfer sheet for circuit formation.

The material of the substrate is not particularly limited, and examples thereof include synthetic resin, glass, metal, ceramics and the like. As a minimum of the average thickness of a substrate, 10 micrometers is preferred, 20 micrometers is more preferred, and 25 micrometers is still more preferred. The upper limit of the average thickness is preferably 300 μm, more preferably 250 μm, and even more preferably 200 μm.

Since the pressure-sensitive adhesive layer is formed from the above-mentioned pressure-sensitive adhesive composition, the pressure-sensitive adhesive layer is effectively cured by irradiation with ultraviolet rays, and its adhesive strength is greatly reduced. As a minimum of average thickness of an adhesive layer, 5 micrometers is preferred, 8 micrometers is more preferred, 10 micrometers is still more preferred, and 15 micrometers is especially preferred. The upper limit of the average thickness is preferably 100 μm, more preferably 75 μm, still more preferably 50 μm, and particularly preferably 40 μm.

<Method for producing adhesive sheet>
As a method for producing the above-mentioned pressure-sensitive adhesive sheet, for example, a process of forming a coating film by applying the pressure-sensitive adhesive composition on one surface of a substrate (hereinafter also referred to as “coating process”) is provided. A manufacturing method etc. are mentioned.

[Coating process]
In the coating process, first, the pressure-sensitive adhesive composition is coated on at least one surface of a sheet-like substrate by a coating apparatus such as an applicator. Next, the said adhesive sheet can be obtained by drying the formed coating film.

The method for producing the pressure-sensitive adhesive sheet usually does not have a step of further forming a cross-linking bond in the coating film after the coating step. Since the pressure-sensitive adhesive sheet is formed using the pressure-sensitive adhesive composition described above, a pressure-sensitive adhesive layer having a sufficiently high pressure-sensitive adhesive force before ultraviolet irradiation is formed in the coating process. Therefore, unlike the conventional pressure-sensitive adhesive composition, a step of further forming a cross-linked bond in the coating film is not required by performing curing by heating and / or standing for several days after the coating step.

<Peeling method of adhesive sheet>
When the pressure-sensitive adhesive sheet is peeled from the adherend, the pressure-sensitive adhesive sheet can be peeled easily and without adhesive residue by irradiating the pressure-sensitive adhesive sheet with ultraviolet rays to cure the pressure-sensitive adhesive layer. The cumulative amount of ultraviolet light for curing the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet can be appropriately selected depending on the average thickness of the pressure-sensitive adhesive layer laminated on the base material, etc. The lower limit of this cumulative light amount is 10 mJ / cm ² is preferable, and 20 mJ / cm ² is more preferable. The upper limit of the integrated light quantity is preferably 4,000 mJ / cm ^2, more preferably 2,000 mJ / cm ^2, more preferably 1,000 mJ / cm ^2. By setting the integrated light quantity of ultraviolet rays within the above range, the pressure-sensitive adhesive layer is more effectively cured, so that the adhesive force can be greatly reduced. Examples of the light source include a high-pressure mercury lamp, a low-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a metal halide lamp, an arc lamp, and a gallium lamp.

Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. The measuring method of various physical property values is shown below.

[Mw]
[A] Mw of the polymer is 2 TPC GPC columns (“TSKgel-Multipore H _XL- M”), flow rate: 1.0 mL / min, elution solvent: tetrahydrofuran, sample concentration: 0.05 mass% Sample injection amount: 100 μL, column temperature: 40 ° C., detector: measured by GPC using monodisperse polystyrene as a standard under the analysis conditions of a differential refractometer.

[Tg]
[A] A solution containing the polymer was thinly stretched on a glass plate and dried at 25 ° C. for 7 days to obtain a dry film. Using a differential scanning calorimeter (“TSC Instruments” “MDSCQ200 type”), the resulting dried film was subjected to a temperature increase rate of 20 ° C./min and a sample amount of 20 mg under the conditions of [A The Tg (° C.) of the polymer was measured.

[Measurement of double bond-containing group (A) and urethane group content]
[A] Each content (% by mass) of the double bond-containing group (A) and the urethane group in the polymer is determined using a nuclear magnetic resonance apparatus (“ASCEND400” from Bruker) and using deuterated chloroform as a measurement solvent. By measuring ¹³ C-NMR, the structure of each structural unit of the structural unit containing the double bond-containing group (A) in the [A] polymer, the structural unit containing the urethane group, and the structural unit other than these structural units Each content ratio was obtained and calculated from these measurement results.

[[A] Measurement of polymer gel fraction]
[A] The gel fraction of the polymer was measured by the following procedure.
(1) Weigh 0.2 g of sample containing [A] polymer into a 50 mL vial.
(2) Add 30 g of toluene to the vial and stir for 30 minutes.
(3) The obtained liquid is put into a glass syringe and filtered through a syringe filter (“Pladisc 25” manufactured by Whatman Japan, PTFE, pore size 0.10 μm), and the obtained filtrate is precisely weighed on an aluminum dish. To do.
(4) The aluminum dish is heated at 150 ° C. for 30 minutes, the solvent is volatilized, and the mass of the obtained solid content is measured (this is designated as W ₁ ).
(5) The gel fraction (% by mass) of the [A] polymer is calculated from the mass W ₁ and the mass W ₂ of the [A] polymer in the sample by (W ₂ −W ₁ ) × 100 / W ₂ Calculated.

<[A] Synthesis of polymer>
[A] Each monomer used for polymer synthesis is shown below.
MA: Methyl acrylate (Toagosei Co., Ltd.)
2EHA: 2-ethylhexyl acrylate (Toagosei Co., Ltd.)
HEA: 2-hydroxyethyl acrylate (Osaka Organic Chemical Co., Ltd.)
HXA: 1,6-hexanediol diacrylate (Kyoeisha Chemical Company)
4HBAGE: 4-hydroxybutyl acrylate glycidyl ether (Nippon Kasei Co., Ltd.)
MMA: Methyl methacrylate (Mitsubishi Rayon)

[Synthesis Example 1]
A 4-necked flask was charged with 39.2 parts by mass of MA as a monomer, 53.5 parts by mass of 2EHA and 7.0 parts by mass of HEA, 2 parts by mass of AIBN as a radical polymerization initiator, and 150 parts by mass of ethyl acetate as a solvent. By reacting at 70 ° C. for 8 hours under an atmosphere, and further reacting at 80 ° C. for 1 hour, a solution containing the polymer (a-1) was obtained. Next, in a 4-neck round bottom flask equipped with a cooler and a thermometer, a solution containing 100 parts by mass of this polymer (a-1) (resin solids equivalent) and 0.01 parts by mass of dibutyltin dilaurate as a reaction catalyst were added. Charge and heat to 40 ° C. with stirring. Next, 2.8 parts by mass of 2-methacryloyloxyethyl isocyanate (“Karenz MOI”, also referred to as “MOI” hereinafter) of Showa Denko KK was added and reacted at 40 ° C. for 5 hours. As a result, the hydroxyl group in the polymer (a-1) reacts with the isocyanate group in the MOI, and the polymer (A-1) having a urethane group and a methacryloyl group as the double bond-containing group (A) in the side chain is obtained. Obtained. The Mw of this polymer (A-1) is 56.4 thousand, Tg is −26.6 ° C., the gel fraction is 5.8% by mass, and the content of the double bond-containing group (A) is 1.2% by mass. The urethane group content was 1.0% by mass.

[Synthesis Examples 2 to 11]
Polymers (A-2) to (A-5) and (CA-1) to (CA-6) were synthesized in the same manner as in Synthesis Example 1 except that the types and amounts of compounds shown in Table 1 were used. did. “AA” which is a double bond-containing group-introducing compound represents acrylic acid (Toagosei Co., Ltd.). Table 1 shows the Mw, Tg, gel fraction (% by mass), double bond-containing group (A) content (% by mass), and urethane group content (% by mass) of the synthesized polymer. “-” In Table 1 indicates that the corresponding component was not used.

<Preparation of pressure-sensitive adhesive composition>
[B] Photopolymerization initiator used for the preparation of the pressure-sensitive adhesive composition is shown below.

[[B] Photopolymerization initiator]
B-1: 1-hydroxycyclohexyl phenyl ketone ("Irgacure 184" from BASF)

[Example 1]
[A] 100 parts by mass of (A-1) as a polymer and [B] 4 parts by mass of (B-1) as a photopolymerization initiator were mixed to prepare an adhesive composition (T-1). .

[Examples 2 to 5 and Comparative Examples 1 to 6]
Adhesive compositions (T-2) to (T-5) and (CT-1) to (CT) were obtained in the same manner as in Example 1 except that the components of the types and contents shown in Table 2 were used. -6) was prepared.

Note that the pressure-sensitive adhesive compositions (T-1) to (T-5) and (CT-1) to (CT-6) prepared above do not substantially contain a thermosetting agent.

<Evaluation>
About the prepared adhesive composition, the adhesive sheet was produced according to the following method, and it evaluated by implementing the following tests about this adhesive sheet.

[Production of adhesive sheet]
Using the prepared pressure-sensitive adhesive composition as it is as a coating solution, it is applied to the surface of a polyethylene terephthalate (PET) film (Toyobo Cosmo Shine 4300, average thickness 100 μm) as a sheet-like substrate using an applicator. Then, by drying at 100 ° C. for 3 minutes, a pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer having an average thickness of 25 μm was laminated on the surface of the base material was obtained. In this pressure-sensitive adhesive sheet, the surface on the pressure-sensitive adhesive layer side was coated with a separator until it was used in order to protect the pressure-sensitive adhesive layer.

[UV adhesive strength]
The prepared adhesive sheet was bonded to an adherend made of SUS304 (Engineering Test Service Co., Ltd.) to prepare a test piece, and then the test piece was subjected to an atmosphere by a 180 ° peel test method in accordance with JIS-Z0237: 2009. The peel strength (unit: N / 25 mm) was measured at a temperature of 23 ° C. and a peeling rate of 300 mm / min.

The UV pre-adhesive strength can be evaluated as “good” when the adherence of SUS304 is 15 N / 25 mm or more, and “bad” when it is less than 15 N / 25 mm.

[After-UV adhesion]
A test piece prepared by the same method as in the above “UV pre-adhesive strength” section was allowed to stand at 23 ° C. for 60 minutes, and then a high-pressure mercury lamp (“IGLANCE” manufactured by Eye Graphics Co. The pressure-sensitive adhesive layer was cured by irradiating ultraviolet rays with an integrated light quantity of 500 mJ / cm ² by the stage ECS-410GX ”). In this case, the pressure-sensitive adhesive layer is irradiated with ultraviolet rays that have passed through the substrate. Next, peel strength was measured under the conditions of an atmosphere of 23 ° C. and a peeling rate of 300 mm / min by a 180 ° peel test method in accordance with JIS-Z0237: 2009.

The post-UV adhesive strength can be evaluated as “good” when it is 1.0 N / 25 mm or less and “bad” when it exceeds 1.0 N / 25 mm with respect to the adherend made of SUS304.

[Adhesive residue]
In the above [Post-UV Adhesive Strength], the adhesive sheet was peeled off from the adherend after irradiation with ultraviolet rays, and then the state of “glue residue” on the surface of the adherend was measured with an optical microscope. Specifically, when no foreign matter having a maximum length of 1 μm or more (a part of the pressure-sensitive adhesive layer) was found on the surface of the adherend, “A” (good) and foreign matter having a size of 1 μm or more were recognized. The case was evaluated as “B” (defective).

[Protruding suppression]
The protrusion suppression was evaluated using a hot press as follows.
(1) Cut the prepared adhesive sheet into a square with a side of 25 mm.
(2) From the upper and lower surfaces of the pressure-sensitive adhesive sheet, the separator of the pressure-sensitive adhesive sheet is not peeled off, and is sandwiched between PET films having an average thickness of 100 μm cut into a square with a side of 35 mm.
(3) While pressing at 40 ° C., pressing is performed under a pressure condition of 0.75 MPa.
(4) The protruding state of the adhesive layer from the end of the adhesive sheet was observed. When the maximum length of the protruding portion is 0.3 mm or less, “A” (good), and “B” (slightly good) when the maximum length exceeds 0.3 mm and less than 1.0 mm. In the case of 0 mm or more, it was evaluated as “C” (defective).

From the results of Table 2, according to the pressure-sensitive adhesive composition of the examples, the pressure-sensitive adhesive layer can be formed without requiring curing, and the pressure-sensitive adhesive force before irradiation with ultraviolet rays is sufficiently high, and the pressure-sensitive adhesive force is reduced by irradiation with ultraviolet rays. It can be seen that the width is sufficiently large and the adhesive residue can be sufficiently reduced. Moreover, it was shown that the adhesive composition of an Example is also excellent in the protrusion suppression property in the case of hot press.

According to the pressure-sensitive adhesive composition and pressure-sensitive adhesive sheet of the present invention, without requiring curing for forming a pressure-sensitive adhesive layer, the pressure-sensitive adhesive force before irradiation with ultraviolet rays is sufficiently high, and the decrease in the pressure-sensitive adhesive force due to ultraviolet irradiation is sufficiently large. Further, the adhesive residue can be sufficiently reduced, and the adhesive layer formed is also excellent in prevention of protrusion. According to the method for producing a pressure-sensitive adhesive sheet of the present invention, a pressure-sensitive adhesive sheet having a sufficiently large decrease in adhesive strength due to ultraviolet irradiation, capable of sufficiently reducing adhesive residue, and having excellent protrusion suppression properties can be produced without requiring curing. can do. Therefore, they can be suitably used in various manufacturing processes such as a semiconductor wafer dicing process.

Claims

A polymer having a structural unit derived from methyl acrylate, a polymerizable carbon-carbon double bond-containing group and a urethane group;
Containing a photopolymerization initiator,
The content ratio of the structural unit with respect to all the structural units constituting the polymer is 1% by mass or more and 60% by mass or less,
The urethane group content in the polymer is 0.5 mass% or more and 2.5 mass% or less,
The gel fraction of the polymer is 5% by mass or more,
A pressure-sensitive adhesive composition containing substantially no thermosetting agent.
The pressure-sensitive adhesive composition according to claim 1, wherein the polymer has the polymerizable carbon-carbon double bond-containing group in a side chain.
The pressure-sensitive adhesive composition according to claim 2, wherein the polymerizable carbon-carbon double bond-containing group is a (meth) acryloyl group.
The pressure-sensitive adhesive composition according to claim 1, 2 or 3, wherein the polymer further has a structural unit derived from a (meth) acrylic acid alkyl ester containing an alkyl group having 4 to 10 carbon atoms.
The pressure-sensitive adhesive composition according to any one of claims 1 to 4, wherein a content of the thermosetting agent is 0.1 parts by mass or less with respect to 100 parts by mass of the polymer.
A sheet-like substrate;
A pressure-sensitive adhesive layer laminated on one surface of the substrate;
The adhesive sheet in which the said adhesive layer is formed from the adhesive composition of any one of Claims 1-5.
It is a manufacturing method of the adhesive sheet according to claim 6,
A method for producing a pressure-sensitive adhesive sheet comprising a step of forming a coating film by applying the pressure-sensitive adhesive composition to one surface of the substrate.
The manufacturing method of the adhesive sheet of Claim 7 which does not have a process which further forms a crosslinked bond in the said coating film after the said coating process.