Pressure-sensitive adhesive composition and pressure-sensitive adhesive sheet

Abstract

An adhesive agent composition comprising a (meth)acrylic resin, a photoinitiator, and a cross-linking agent, wherein: the (meth)acrylic resin is a di-block copolymer formed of block X and block Y; the structural unit ratio (mole ratio) of block X and block Y is 40:60 to 95:5; block X has a structural unit (M-1) having a hydroxy group and a structural unit (M-2) having an ethylenically unsaturated group; block Y has a structural unit (M-3) derived from an ethylenically unsaturated compound (m-3) having an SP value of 20 (J / cm3)1 / 2 or less; at least one of the structural units (M-1) to (M-3) has a structure derived from a (meth)acryloyloxy group; in block X, the proportion of the total of the structural units (M-1) and (M-2) with respect to all structural units is 18-95 mol%; and, in block Y, the proportion of the total of the structural units (M-1) and (M-2) with respect to all structural units is 0-17 mol%.

Description

[Technical Field]

[0001] The present disclosure relates to a pressure-sensitive adhesive composition using a (meth)acrylic resin, and also to a pressure-sensitive adhesive sheet, a dicing tape, and a dicing / die-bonding integrated film having a pressure-sensitive adhesive layer made of a cured product of the pressure-sensitive adhesive composition. [Background technology]

[0002] Blade dicing has traditionally been the primary method for manufacturing stacked semiconductor chips from semiconductor wafers made from silicon (Si), gallium arsenide (GaAs), and other materials. In this method, the semiconductor wafer undergoes a circuit formation process on its front surface and a backside polishing process before being attached to a dicing tape. In the dicing process, the wafer is cut and separated (diced) into fine semiconductor chips using a high-speed rotating blade. After the dicing process, the semiconductor wafer undergoes a cleaning process before being subjected to a pick-up process in which the semiconductor chips are picked up. In this pick-up process, the adhesive layer of the dicing tape is first irradiated with energy rays such as ultraviolet light to harden the adhesive layer and reduce its adhesive strength. The dicing tape is then expanded, pushed up from the backside with a pin, and the semiconductor chips are picked up by vacuum suction.

[0003] In blade dicing, cutting water is constantly supplied to the blade to cool it, which generates heat during cutting, and to remove cutting debris. If cutting water seeps into the gap between the dicing tape and the semiconductor wafer, adhesive strength will decrease significantly, so the dicing tape must have excellent water resistance.

[0004] As an example of a dicing tape with excellent water resistance, Patent Document 1 (JP 2012-216841 A) proposes a dicing tape in which a pressure-sensitive adhesive layer is formed on a base resin film, the pressure-sensitive adhesive layer being made of an acrylic polymer having a radiation-polymerizable carbon-carbon double bond in the molecule and a photopolymerization initiator to which polypropylene oxide of a specific number average molecular weight has been added. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-216841 Summary of the Invention [Problem to be solved by the invention]

[0006] The dicing tape used in the dicing process is typically a resin film substrate coated with an adhesive, such as an acrylic adhesive, to form an adhesive layer. Dicing tape supports the semiconductor wafer, preventing the cut semiconductor chips from scattering during dicing. In recent years, semiconductor chips have become increasingly miniaturized, reducing the area supported by the dicing tape per chip. This has led to a demand for improved adhesive strength for dicing tapes. Additionally, as semiconductor chips become smaller, a higher level of water resistance is also required. However, the adhesive strength of the dicing tape proposed in Patent Document 1 is low and insufficient for supporting fine chips.

[0007] The present disclosure provides a pressure-sensitive adhesive composition that provides a pressure-sensitive adhesive sheet having excellent water resistance, sufficient adhesion to an adherend, and excellent releasability after UV irradiation. Furthermore, the present disclosure provides a pressure-sensitive adhesive sheet, a dicing tape, and a dicing-die bonding integrated film that have a pressure-sensitive adhesive layer formed from a cured product of the pressure-sensitive adhesive composition. More specifically, the present disclosure provides a dicing tape and a dicing-die bonding integrated film that have excellent water resistance, good dicing properties, and excellent pickup properties after UV irradiation. [Means for solving the problem]

[0008] The present disclosure includes the following aspects. [1] a (meth)acrylic resin (A); a photopolymerization initiator (B); a crosslinking agent (C); Contains the (meth)acrylic resin (A) is a diblock copolymer consisting of an X block and a Y block, the structural unit ratio (molar ratio) of the X block to the Y block is 40:60 to 95:5; The X block is a structural unit (M-1) having a hydroxy group, and Structural unit (M-2) having an ethylenically unsaturated group and The Y block is SP value is 20 (J / cm 3 ) 1 / 2 Structural units (M-3) derived from the following ethylenically unsaturated compounds (m-3), and Optionally, one or more structural units selected from the group consisting of a structural unit (M-1) having a hydroxy group and a structural unit (M-2) having an ethylenically unsaturated group. and at least one of the structural unit (M-1), the structural unit (M-2), and the structural unit (M-3) has a structure derived from a (meth)acryloyloxy group; the total proportion of the structural unit (M-1) having a hydroxy group and the structural unit (M-2) having an ethylenically unsaturated group in the X block is 18 to 95 mol % relative to 100 mol % of the total structural units in the X block; a pressure-sensitive adhesive composition, wherein the total proportion of the structural unit (M-1) having a hydroxy group and the structural unit (M-2) having an ethylenically unsaturated group in the Y block is 0 to 17 mol %, relative to 100 mol % of the total structural units in the Y block. [2] The pressure-sensitive adhesive composition according to [1], wherein the proportion of the structural unit (M-2) having an ethylenically unsaturated group in the X block is 1 to 60 mol %, with the total of the structural units in the X block being 100 mol %. [3] The pressure-sensitive adhesive composition according to [1] or [2], wherein the proportion of the structural unit (M-1) having a hydroxy group in the X block is 0.1 to 35 mol %, with the total of the structural units in the X block being 100 mol %. [4] The pressure-sensitive adhesive composition according to any one of [1] to [3], wherein the structural unit (M-2) having an ethylenically unsaturated group contained in the X block is a structural unit in which an isocyanato group-containing ethylenically unsaturated compound (a) is added to a hydroxy group of a structural unit derived from an ethylenically unsaturated compound (m-1) having a hydroxy group. [5] The SP value of the Y block is 20 (J / cm 3 ) 1 / 2 The pressure-sensitive adhesive composition according to any one of [1] to [4], wherein the proportion of structural units (M-3) derived from the following ethylenically unsaturated compound (m-3) is 70 mol % or more, with the total of the structural units of the Y block being 100 mol %: [6] The SP value of the Y block is 20 (J / cm 3 ) 1 / 2 The pressure-sensitive adhesive composition according to any one of [1] to [5], wherein the structural unit (M-3) derived from the following ethylenically unsaturated compound (m-3) is a structural unit derived from a monomer selected from the group consisting of linear or branched alkyl (meth)acrylates having an alkyl group with 6 to 30 carbon atoms, alicyclic skeleton-containing (meth)acrylates, and styrene. [7] The pressure-sensitive adhesive composition according to any one of [1] to [6], wherein the Y block has a structural unit derived from styrene. [8] The X block is a linear or branched alkyl group having 1 to 6 carbon atoms in the alkyl group ( [7] The composition according to any one of [1] to [7], further comprising a structural unit derived from a methacrylate. Pressure-sensitive adhesive composition. [9] The (meth)acrylic resin (A) has a weight average molecular weight of 1×10 4 ~200×10 4The pressure-sensitive adhesive composition according to any one of [1] to [8], wherein

[10] The pressure-sensitive adhesive composition according to any one of [1] to [9], wherein the (meth)acrylic resin (A) has an ethylenically unsaturated group equivalent of 100 to 5000 g / mol.

[11] The pressure-sensitive adhesive composition according to any one of [1] to

[10] , wherein the (meth)acrylic resin (A) has a hydroxyl value of 0.01 to 50 mgKOH / g.

[12] a substrate layer; a pressure-sensitive adhesive layer comprising a heat-cured or photo-cured product of the pressure-sensitive adhesive composition according to any one of [1] to

[11] ; An adhesive sheet having the above structure.

[13] a substrate layer; a pressure-sensitive adhesive layer comprising a heat-cured or photo-cured product of the pressure-sensitive adhesive composition according to any one of [1] to

[11] ; A dicing tape having

[14] a substrate layer; a pressure-sensitive adhesive layer comprising a heat-cured or photo-cured product of the pressure-sensitive adhesive composition according to any one of [1] to

[11] ; an adhesive layer; This is a dicing and die bonding integrated film that has the above in order. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to provide a pressure-sensitive adhesive composition that provides a pressure-sensitive adhesive sheet having high adhesive strength and excellent water resistance, and whose adhesive strength significantly decreases upon irradiation with ultraviolet light. According to the present disclosure, it is possible to provide a pressure-sensitive adhesive sheet, a dicing tape, and a dicing / die bonding integrated film that have a pressure-sensitive adhesive layer made of a cured product of the pressure-sensitive adhesive composition. According to the present disclosure, it is possible to provide a pressure-sensitive adhesive sheet that has excellent water resistance and sufficient adhesive strength to an adherend, and has excellent releasability after UV irradiation. Also provided are a dicing tape and a dicing / die bonding integrated film that suppress chip fly-off of fine semiconductor chips and allows easy pick-up of the semiconductor chips after UV irradiation. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the embodiments described below.

[0011] In this specification, when "~" is used to describe a numerical range, the numerical values at both ends are the upper and lower limits, respectively, and are included in the numerical range. When multiple upper or lower limits are listed, numerical ranges can be created using all combinations of the upper and lower limits. Similarly, when multiple numerical ranges are listed, separate numerical ranges can be created by individually selecting and combining upper and lower limits from those numerical ranges.

[0012] In this specification, "(meth)acrylic" means methacrylic or acrylic, "(meth)acrylate" means acrylate or methacrylate, and "(meth)acryloyloxy" means acryloyloxy or methacryloyloxy.

[0013] In this specification, the term "structural unit" refers to a unit derived from a polymerizable compound used as a monomer or a unit obtained by further modifying a unit derived from a polymerizable compound used as a monomer.

[0014] In this specification, the term "photocrosslinkable pressure-sensitive adhesive" refers to a thermoset product of a pressure-sensitive adhesive composition that has photocrosslinkability in the thermoset state. The photocrosslinkable pressure-sensitive adhesive can be crosslinked by ultraviolet irradiation.

[0015] In this specification, the term "photothermally cured product" refers to a product obtained by crosslinking the above-mentioned photocrosslinkable pressure-sensitive adhesive by irradiating it with ultraviolet light.

[0016] In this specification, the "weight average molecular weight (Mw)" and "number average molecular weight (Mn)" are values measured at room temperature (23°C) using gel permeation chromatography (GPC) under the following conditions and calculated using a standard polystyrene calibration curve. Equipment: Shodex (trademark) GPC-101 (Resonac Co., Ltd.) Column: Shodex (trademark) LF-804 (Resonac Co., Ltd.) Column temperature: 40℃ Sample: 0.2% by mass of sample in tetrahydrofuran Flow rate: 1mL / min Eluent: tetrahydrofuran Detector: Shodex (trademark) RI-71S (Resonac Corporation)

[0017] As used herein, the term "glass transition temperature (Tg)" refers to the endothermic onset temperature due to glass transition observed when a 10 mg sample is collected and subjected to differential scanning calorimetry using a differential scanning calorimeter (DSC) while changing the temperature of the sample from -100°C to 200°C at a heating rate of 10°C / min. When two or more endothermic onset temperatures are observed, Tg is the simple average of the two or more endothermic onset temperatures.

[0018] [Adhesive composition] The pressure-sensitive adhesive composition contains a (meth)acrylic resin (A), a photopolymerization initiator (B), a crosslinking agent (C), and other components added as needed. The pressure-sensitive adhesive composition containing the (meth)acrylic resin (A) is suitable for use in removable pressure-sensitive adhesive sheets, particularly dicing tapes and integrated dicing and die bonding films.

[0019] <(Meth)acrylic resin (A)> The (meth)acrylic resin (A) is a diblock copolymer consisting of an X block and a Y block. The (meth)acrylic resin (A) has at least one structure derived from a (meth)acryloyloxy group. The structural unit ratio (molar ratio) of the X block to the Y block is 40:60 to 95:5. When raw material monomers containing a monomer that contributes to adhesiveness and a monomer that contributes to water resistance are subjected to free radical polymerization, the properties of the monomers are averaged in the resulting copolymer, making it difficult to fully utilize the characteristics of each monomer type. The present inventors investigated copolymers having multiple types of blocks containing specific structural units in order to better utilize the characteristics of each monomer type. As a result, they found that a diblock copolymer consisting of two types of blocks containing specific structural units can provide a pressure-sensitive adhesive composition with excellent water resistance and adhesive strength.

[0020] The structural unit ratio of the X block is 40 mol% or more, preferably 50 mol% or more, and more preferably 55 mol% or more, based on the total structural units of the (meth)acrylic resin (A). The structural unit ratio of the X block is 95 mol% or less, preferably 90 mol% or less, and more preferably 85 mol% or less, based on the total structural units of the (meth)acrylic resin (A). Any combination of these lower and upper limits is acceptable. When the structural unit ratio of the X block is 40 mol% or more, the pressure-sensitive adhesive layer has sufficient adhesive strength to the substrate. Therefore, when used as a dicing tape or a dicing-die bonding integrated film, the dicing performance is sufficient. When the structural unit ratio of the X block is 95 mol% or less, the pressure-sensitive adhesive layer has sufficient water resistance to the substrate. Therefore, when used as a dicing tape or a dicing-die bonding integrated film, the pressure-sensitive adhesive layer has sufficient adhesive strength in processes using water, such as cutting water.

[0021] The structural unit ratio of the Y block is 5 mol% or more, preferably 10 mol% or more, and more preferably 15 mol% or more, based on the total structural units of the (meth)acrylic resin (A). The structural unit ratio of the Y block is 60 mol% or less, preferably 50 mol% or less, and more preferably 45 mol% or less, based on the total structural units of the (meth)acrylic resin (A). Any combination of these lower and upper limits is acceptable. When the structural unit ratio of the Y block is 5 mol% or more, the pressure-sensitive adhesive layer can have sufficient water resistance to the substrate. Therefore, when used as a dicing tape or a dicing / die-bonding integrated film, the adhesive strength is sufficient in processes using water, such as cutting water. When the structural unit ratio of the Y block is 60 mol% or less, the adhesive layer can have sufficient adhesive strength to the substrate. Therefore, when used as a dicing tape or a dicing / die-bonding integrated film, the dicing performance is sufficient.

[0022] The X block has a structural unit (M-1) having a hydroxy group (also referred to as structural unit (M-1)) and a structural unit (M-2) having an ethylenically unsaturated group (also referred to as structural unit (M-2)). The X block further has a structural unit (M-4) (also referred to as structural unit (M-4)) other than the structural unit (M-1) and the structural unit (M-2). The total proportion of the structural unit (M-1) having a hydroxy group and the structural unit (M-2) having an ethylenically unsaturated group in the X block is 18 mol% or more, preferably 19 mol% or more, and more preferably 20 mol% or more, based on 100 mol% of the total structural units in the X block. The total proportion of the structural unit (M-1) having a hydroxy group and the structural unit (M-2) having an ethylenically unsaturated group in the X block is 95 mol% or less, preferably 60 mol% or less, and more preferably 40 mol% or less, based on 100 mol% of the total structural units in the X block. Any combination of these lower and upper limits may be used.

[0023] The Y block has an SP value of 20 (J / cm 3 )1 / 2 The Y block has a structural unit (M-3) (also referred to as structural unit (M-3)), which is derived from the following ethylenically unsaturated compound (m-3) (also referred to as compound (m-3)), and which does not have an ethylenically unsaturated group or a hydroxy group. The Y block may optionally have a structural unit other than the structural unit (M-3) selected from the group consisting of a structural unit (M-1) having a hydroxy group, a structural unit (M-2) having an ethylenically unsaturated group, and a structural unit (M-5) (also referred to as structural unit (M-5)) other than the structural units (M-1) to (M-3). The total proportion of the structural unit (M-1) having a hydroxy group and the structural unit (M-2) having an ethylenically unsaturated group in the Y block is 0 mol % or more, or may be 3 mol % or more, or may be 5 mol % or more, relative to the total structural units of the Y block being 100 mol %. The total proportion of the structural unit (M-1) having a hydroxy group and the structural unit (M-2) having an ethylenically unsaturated group in the Y block is 17 mol % or less, preferably 15 mol % or less, and more preferably 10 mol % or less, based on 100 mol % of the total structural units in the Y block. Any combination of these lower and upper limits may be used.

[0024] When the pressure-sensitive adhesive composition contains a (meth)acrylic resin (A), sufficient adhesion to the adherend is obtained, mainly due to the contribution of the X block, and excellent releasability from the adherend is obtained after UV irradiation. When the pressure-sensitive adhesive composition contains a (meth)acrylic resin (A), a pressure-sensitive adhesive sheet with good water resistance is obtained, mainly due to the contribution of the Y block. Therefore, dicing tapes and integrated dicing and die bonding films using a pressure-sensitive adhesive composition containing a (meth)acrylic resin (A) in the pressure-sensitive adhesive layer have excellent water resistance even in processes using water, such as cutting water, good dicing properties, and excellent pickup properties for singulated semiconductor chips after UV irradiation.

[0025] The weight average molecular weight (Mw) of the (meth)acrylic resin (A) is preferably 1×10 4 More preferably, it is 3×10 4or more, and more preferably 10×10 4 The weight average molecular weight (Mw) of the (meth)acrylic resin (A) is preferably 200×10 4 or less, and more preferably 150×10 4 or less, and more preferably 100×10 4 The weight average molecular weight (Mw) is 1×10 or less. Any combination of these lower and upper limits may be used. 4 When the weight average molecular weight (Mw) is 200×10 or more, the adhesive strength of the adhesive sheet obtained by curing the adhesive composition is good, and when the adhesive sheet is used as a dicing tape or a dicing / die bonding integrated film, the dicing property is good. 4 When the viscosity is less than 100 ppm, the adhesive layer has sufficient peelability after UV irradiation, and when the adhesive sheet is used as a dicing tape or a dicing / die bonding integrated film, it has good pick-up properties. Furthermore, the adhesive layer has sufficient strength, and contamination of the adherend when the adhesive sheet is peeled off can be prevented. In addition, the viscosity of the adhesive composition can be controlled within an appropriate range, ensuring workability when applying it to a substrate to prepare an adhesive sheet, and making it possible to obtain a uniform film thickness.

[0026] The molecular weight distribution (Mw / Mn) of the (meth)acrylic resin (A) may be 1.1 or more, 1.3 or more, or 1.5 or more. The molecular weight distribution (Mw / Mn) of the (meth)acrylic resin (A) is preferably 5.0 or less, more preferably 4.5 or less, and even more preferably 4.0 or less. Any combination of these lower and upper limits may be used. A molecular weight distribution of 1.1 or more makes it easy to control the production conditions. A molecular weight distribution of 5.0 or less provides a more effective pressure-sensitive adhesive composition than one synthesized by free radical polymerization without controlling the molecular weight distribution. That is, by narrowing the molecular weight distribution, on the one hand, the influence of the low molecular weight (meth)acrylic resin (A) on the dicing properties, pick-up properties, and adherend contamination of the pressure-sensitive adhesive sheet can be reduced. On the other hand, the influence of the high molecular weight (meth)acrylic resin (A) on viscosity control of the pressure-sensitive adhesive composition can be reduced, ensuring stable pressure-sensitive adhesive sheet performance.

[0027] The ethylenically unsaturated group equivalent of the (meth)acrylic resin (A) is preferably 100 g / mol or more, more preferably 250 g / mol or more, and even more preferably 500 g / mol or more. The ethylenically unsaturated group equivalent of the (meth)acrylic resin (A) is preferably 5,000 g / mol or less, more preferably 3,000 g / mol or less, and even more preferably 2,000 g / mol or less. Any combination of these lower and upper limits may be used. When the ethylenically unsaturated group equivalent of the (meth)acrylic resin (A) is 100 g / mol or more, compatibility with common organic solvents is improved. When the ethylenically unsaturated group equivalent of the (meth)acrylic resin (A) is 5,000 g / mol or less, sufficient releasability of the pressure-sensitive adhesive layer after UV irradiation is obtained, and when the pressure-sensitive adhesive sheet is used as a dicing tape or a dicing / die-bonding integrated film, good pick-up properties are obtained.

[0028] In this specification, the ethylenically unsaturated group equivalent of the (meth)acrylic resin (A) refers to the mass of the (meth)acrylic resin (A) per mole of ethylenically unsaturated bond. In one embodiment, the ethylenically unsaturated group equivalent of the (meth)acrylic resin (A) is a calculated value calculated from the amounts of raw materials used in the production of the (meth)acrylic resin (A), assuming that 100% of the raw materials have reacted. The ethylenically unsaturated group equivalent of the (meth)acrylic resin (A) may be calculated from the amount of halogen bonded to the (meth)acrylic resin (A). The amount of halogen bonded to the (meth)acrylic resin (A) can be evaluated in accordance with JIS K 0070:1992.

[0029] The glass transition temperature (Tg) of the (meth)acrylic resin (A) is preferably −80° C. to 0° C., more preferably −70° C. to −10° C., and even more preferably −65° C. to −20° C. If the glass transition temperature is −80° C. or higher, the pickup property is good. If the glass transition temperature is 0° C. or lower, the adhesion before UV irradiation is good.

[0030] The hydroxyl value of the (meth)acrylic resin (A) is preferably 0.01 mgKOH / g or more, more preferably 2.5 mgKOH / g or more, and even more preferably 5 mgKOH / g or more. The hydroxyl value of the (meth)acrylic resin (A) is preferably 50 mgKOH / g or less, more preferably 30 mgKOH / g or less, and even more preferably 15 mgKOH / g or less. Any combination of these lower and upper limits is acceptable. When the hydroxyl value of the (meth)acrylic resin (A) is 0.01 mgKOH / g or more, the resin can be sufficiently thermally cured by a crosslinking reaction upon heating, resulting in good adhesive strength of the resulting pressure-sensitive adhesive sheet. Therefore, when the pressure-sensitive adhesive sheet is used as a dicing tape or a dicing / die-bonding integrated film, good dicing properties are achieved. Furthermore, sufficient strength of the pressure-sensitive adhesive layer can be obtained, preventing contamination of the adherend when the pressure-sensitive adhesive sheet is peeled off. When the hydroxyl value of the (meth)acrylic resin (A) is 50 mgKOH / g or less, the amount of hydroxyl groups contained in the adhesive layer after heat curing is sufficiently reduced, and the resulting adhesive sheet has good water resistance. Therefore, when the adhesive sheet is used as a dicing tape or a dicing / die bonding integrated film, the adhesive sheet has excellent water resistance even in processes that use water, such as cutting water, and has good dicing properties.

[0031] In this specification, the hydroxyl value of the (meth)acrylic resin (A) is a value measured using a mixed indicator of bromothymol blue and phenol red in accordance with JIS K0070: 1992. The hydroxyl value of the resin means the mass (mg) of potassium hydroxide required to neutralize acetic acid bonded to hydroxyl groups when 1 g of the resin is acetylated.

[0032] (X block of (meth)acrylic resin (A)) The X block of the (meth)acrylic resin (A) has a structural unit (M-1) having a hydroxy group and a structural unit (M-2) having an ethylenically unsaturated group, and further has a structural unit (M-4) other than the structural units (M-1) and (M-2).

[0033] <Structural unit (M-1) having a hydroxy group> The structural unit (M-1) is a structural unit that does not have an ethylenically unsaturated group but has a hydroxy group. The structural unit (M-1) is preferably a structural unit derived from a compound having a hydroxy group and a (meth)acryloyloxy group. When the (meth)acrylic resin (A) has the structural unit (M-1), a pressure-sensitive adhesive sheet with sufficient adhesive strength can be obtained. In addition, crosslinking points with the crosslinking agent (C) described below can be secured, thereby improving the strength of the pressure-sensitive adhesive layer. The structural unit (M-1) may be of only one type, or of two or more types.

[0034] The content of the structural unit (M-1) in the X block is preferably 0.1 mol% or more, more preferably 1 mol% or more, and even more preferably 1.5 mol% or more, based on 100 mol% of the total structural units in the X block of the (meth)acrylic resin (A). The content of the structural unit (M-1) in the X block is preferably 35 mol% or less, more preferably 20 mol% or less, and even more preferably 10 mol% or less, based on 100 mol% of the total structural units in the X block of the (meth)acrylic resin (A). Any combination of these lower and upper limits is acceptable. When the content of the structural unit (M-1) in the X block is 0.1 mol% or more, the resin can be sufficiently thermally cured by a crosslinking reaction caused by heating. In addition, the resulting pressure-sensitive adhesive sheet has good adhesive strength, and when the pressure-sensitive adhesive sheet is used as a dicing tape or a dicing / die-bonding integrated film, the dicing properties are good. Furthermore, sufficient strength of the pressure-sensitive adhesive layer is obtained, preventing contamination of the adherend when the pressure-sensitive adhesive sheet is peeled off. When the content of the structural unit (M-1) in the X block is 35 mol% or less, the amount of hydroxyl groups contained in the pressure-sensitive adhesive layer after heat curing is sufficiently reduced, and the resulting pressure-sensitive adhesive sheet has good water resistance. Therefore, when the pressure-sensitive adhesive sheet is used as a dicing tape or a dicing / die-bonding integrated film, the pressure-sensitive adhesive sheet has excellent water resistance even in processes that use water, such as cutting water, and has good dicing properties.

[0035] The structural unit (M-1) is a structural unit derived from an ethylenically unsaturated compound (m-1) having a hydroxy group (also referred to as compound (m-1)). The ethylenically unsaturated compound (m-1) having a hydroxy group is not particularly limited as long as it is a compound having a hydroxy group and one ethylenically unsaturated group. Specific examples include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2,3-dihydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; (meth)acrylates having an aromatic ring and a hydroxy group such as hydroxyphenyl (meth)acrylate and 2-hydroxy-3-phenoxypropyl (meth)acrylate; and hydroxystyrene. Among these, from the viewpoint of curability when combined with a crosslinking agent (C) described below, hydroxyalkyl(meth)acrylates are preferred, hydroxyalkyl(meth)acrylates in which the hydroxyalkyl group has 1 to 6 carbon atoms are more preferred, hydroxyalkyl(meth)acrylates in which the linear alkyl group has a hydroxy group at the end are even more preferred, and 2-hydroxyethyl(meth)acrylate, 3-hydroxypropyl(meth)acrylate, and 4-hydroxybutyl(meth)acrylate are particularly preferred.

[0036] <Structural Unit (M-2) Having an Ethylenically Unsaturated Group> The structural unit (M-2) is a structural unit having an ethylenically unsaturated group. The structural unit (M-2) is preferably a structural unit derived from a (meth)acrylate (m-2) having an ethylenically unsaturated group other than a (meth)acryloyloxy group, as described below, or a compound having a (meth)acryloyloxy group but no ethylenically unsaturated group other than a (meth)acryloyloxy group. When the (meth)acrylic resin (A) contains the structural unit (M-2), a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer using the resin is applied to an adherend, and then irradiated with UV light to reduce the adhesive strength, allowing for easy peeling from the adherend. When the pressure-sensitive adhesive sheet is used as a dicing tape or a dicing / die-bonding integrated film, it exhibits good dicing properties and excellent pickup properties after UV irradiation. The structural unit (M-2) may be of one type or two or more types.

[0037] The content of the structural unit (M-2) in the X block is preferably 1 mol% or more, more preferably 8 mol% or more, and even more preferably 15 mol% or more, based on 100 mol% of the total structural units in the X block of the (meth)acrylic resin (A). The content of the structural unit (M-2) in the X block is preferably 60 mol% or less, more preferably 40 mol% or less, and even more preferably 30 mol% or less, based on 100 mol% of the total structural units in the X block of the (meth)acrylic resin (A). Any combination of these lower and upper limits is acceptable. When the content of the structural unit (M-2) in the X block is 1 mol% or more, sufficient releasability is obtained after UV irradiation of the pressure-sensitive adhesive sheet, and good pick-up properties are obtained when the pressure-sensitive adhesive sheet is used as a dicing tape or a die-bonding / die-bonding integrated film. When the content of the structural unit (M-2) in the X block is 60 mol% or less, good compatibility with common organic solvents is achieved.

[0038] In one embodiment, the structural unit (M-2) is a structural unit derived from a (meth)acrylate (m-2) (also referred to as compound (m-2)) having an ethylenically unsaturated group other than a (meth)acryloyloxy group. Examples of the compound (m-2) include alkenyl (meth)acrylates such as vinyl (meth)acrylate, allyl (meth)acrylate, isopropenyl (meth)acrylate, and 2-butenyl (meth)acrylate; and (meth)acrylates containing an unsaturated alicyclic skeleton such as dicyclopentenyloxyethyl (meth)acrylate and dicyclopentenyl (meth)acrylate. Among these, from the viewpoint of reaction control, alkenyl (meth)acrylates are preferred, allyl (meth)acrylate, isopropenyl (meth)acrylate, and 2-butenyl (meth)acrylate are more preferred, and isopropenyl (meth)acrylate is even more preferred.

[0039] In one embodiment, the structural unit (M-2) is a structural unit in which the isocyanato group of the isocyanato group-containing ethylenically unsaturated compound (a) is added to the hydroxy group of the structural unit derived from the hydroxy group-containing ethylenically unsaturated compound (m-1). Specifically, the isocyanato group-containing ethylenically unsaturated compound (a) is not particularly limited as long as it has no hydroxy group and has one isocyanato group and an ethylenically unsaturated group. Specific examples include (meth)acryloyloxyalkyl isocyanates such as 2-isocyanatoethyl (meth)acrylate, 2-isocyanatopropyl (meth)acrylate, 3-isocyanatopropyl (meth)acrylate, 2-isocyanato-1-methylethyl (meth)acrylate, 2-isocyanato-1,1-dimethylethyl (meth)acrylate, and 4-isocyanatocyclohexyl (meth)acrylate; 2-(2-isocyanatoethyloxy)ethyl (meth)acrylate; 1,1-(bis(meth)acryloyloxymethyl)ethyl isocyanate, etc. Among these, from the viewpoint of ease of synthesis of the (meth)acrylic resin (A), (meth)acryloyloxyalkyl isocyanates are preferred, and 2-(meth)acryloyloxyethyl isocyanate is more preferred.

[0040] When the structural unit (M-2) is introduced by adding an isocyanato group-containing ethylenically unsaturated compound (a) to a portion of the hydroxy groups of the structural unit derived from the hydroxy group-containing ethylenically unsaturated compound (m-1) of the (meth)acrylic copolymer, the addition rate of the isocyanato group-containing ethylenically unsaturated compound (a) relative to the number of moles of hydroxy groups is preferably 40 mol% or more, more preferably 60 mol% or more, and even more preferably 80 mol% or more. The addition rate of the isocyanato group-containing ethylenically unsaturated compound (a) is preferably 99 mol% or less, more preferably 98 mol% or less, and even more preferably 95 mol% or less. Any combination of these lower and upper limits is acceptable. When the addition rate of the isocyanato group-containing ethylenically unsaturated compound (a) is 40 mol% or more, the pressure-sensitive adhesive sheet exhibits sufficient releasability after ultraviolet irradiation, and when the pressure-sensitive adhesive sheet is used as a dicing tape or a dicing / die-bonding integrated film, good pick-up properties are obtained. When the addition rate of the isocyanato group-containing ethylenically unsaturated compound (a) is 99 mol% or less, the resin can be sufficiently thermally cured by a crosslinking reaction caused by heating. In addition, the adhesive strength of the resulting adhesive sheet is good. Therefore, when the adhesive sheet is used as a dicing tape or a dicing / die bonding integrated film, the dicing properties are good. Furthermore, sufficient strength of the adhesive layer can be obtained, preventing contamination of the adherend when the adhesive sheet is peeled off.

[0041] Other structural units The X block of the (meth)acrylic resin (A) further has a structural unit (M-4) other than the structural unit (M-1) and the structural unit (M-2). The structural unit (M-4) may be of only one type, or may be of two or more types.

[0042] The content of the other structural unit (M-4) in the X block is 5 mol% or more, preferably 25 mol% or more, and more preferably 50 mol% or more, based on 100 mol% of the total structural units in the X block of the (meth)acrylic resin (A). The content of the other structural unit (M-4) in the X block is 82 mol% or less, preferably 78 mol% or less, more preferably 75 mol% or less, and even more preferably 70 mol% or less, based on 100 mol% of the total structural units in the X block of the (meth)acrylic resin (A). Any combination of these lower and upper limits is acceptable. When the content of the other structural unit (M-4) in the X block is 5 mol% or more, the resulting pressure-sensitive adhesive sheet has good adhesive strength. Therefore, when the pressure-sensitive adhesive sheet is used as a dicing tape or a dicing / die-bonding integrated film, the dicing properties are good. When the content of other structural units (M-4) in the X block is 82 mol% or less, the (meth)acrylic resin (A) contains sufficient hydroxyl groups and ethylenically unsaturated groups, resulting in good thermosetting properties and good resistance to deterioration of adhesive strength due to ultraviolet irradiation. Therefore, when the pressure-sensitive adhesive sheet is used as a dicing tape or a dicing / die bonding integrated film, it exhibits good dicing properties and pick-up properties.

[0043] Examples of compounds that provide the other structural unit (M-4) include monomers other than the compounds (m-1) and (m-2) that are copolymerizable with the compounds (m-1) and (m-2). Specific examples include alkyl (meth)acrylates, carboxyl group-containing monomers, dienes such as butadiene and dicyclopentadiene, styrenes, unsaturated dicarboxylic acid diesters, and other vinyl compounds.

[0044] Examples of alkyl (meth)acrylates include linear or branched alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, neopentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isoamyl (meth)acrylate, and dodecyl (meth)acrylate; and alicyclic alkyl (meth)acrylates such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, ethylcyclohexyl (meth)acrylate, norbornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, isobornyl (meth)acrylate, and adamantyl (meth)acrylate. Among these, from the viewpoint of reactivity, linear or branched alkyl(meth)acrylates in which the alkyl group has 1 to 5 carbon atoms, and cyclohexyl(meth)acrylate are preferred, and it is more preferred to use at least n-butyl(meth)acrylate.

[0045] Examples of the carboxy group-containing monomer include unsaturated monobasic acids such as (meth)acrylic acid, crotonic acid, vinylbenzoic acid, and acrylic acid substituted with a haloalkyl, alkoxyl, halogen, nitro, or cyano at the α-position, and unsaturated dibasic acids such as itaconic acid. Among these, (meth)acrylic acid is preferred because of the ease of producing the pressure-sensitive adhesive layer.

[0046] Specific examples of styrenes include styrene and α-, o-, m-, or p-alkyl derivatives of styrene.

[0047] Specific examples of the unsaturated dicarboxylic acid diester include diethyl citraconate, diethyl maleate, diethyl fumarate, and diethyl itaconate.

[0048] Specific examples of other vinyl compounds include norbornene (bicyclo[2.2.1]hept-2-ene), 5-methylbicyclo[2.2.1]hept-2-ene, 5-ethylbicyclo[2.2.1]hept-2-ene, tetracyclo[4.4.0.1 2,5 .1 7,1 0 ]dodec-3-ene, 8-methyltetracyclo[4.4.0.1 2,5 .1 7,10 ]dodec-3-ene, 8-ethyltetracyclo[4.4.0.1 2,5 .1 7,10 ]dodec-3-ene, tricyclo[5.2.1.0 2,6 ]dec-8-ene, tricyclo[5.2.1.0 2,6 ]dec-3-ene, tricyclo[4.4.0.1 2,5 ]undec-3-ene, tricyclo[6.2.1.0 1,8 ]undec-9-ene, tricyclo[6.2.1.0 1,8 ]undec-4-ene, tetracyclo[4.4.0.1 2,5 .1 7,1 0 .0 1,6 ]dodec-3-ene, 8-methyltetracyclo[4.4.0.1 2,5 .1 7,10 .0 1,6 ]dodec-3-ene, 8-ethylidenetetracyclo[4.4.0.1 2,5 .1 7,12 ]dodec-3-ene, 8-ethylidenetetracyclo[4.4.0.1 2,5 .1 7,10 .0 1,6 ]dodec-3-ene, pentacyclo[6.5.1.1 3, 6 .0 2,7 .0 9,13 ]pentadec-4-ene, pentacyclo[7.4.0.1 2, 5 .1 9,12 .0 8,13 ]pentadec-3-ene, (meth)acrylic acid anilide, vinylpyridine, vinyl acetate, and the like.

[0049] Among these, alkyl(meth)acrylates are preferred from the viewpoint of reaction control, and linear or branched alkyl(meth)acrylates in which the alkyl group has 1 to 5 carbon atoms are more preferred.

[0050] <Y-block of (meth)acrylic resin (A)> The Y block of (meth)acrylic resin (A) has an SP value of 20 (J / cm 3 ) 1 / 2 The Y block has a structural unit (M-3) derived from the following ethylenically unsaturated compound (m-3): The Y block may, if necessary, have a structural unit other than the structural unit (M-3) selected from the group consisting of a structural unit (M-1) having a hydroxy group, a structural unit (M-2) having an ethylenically unsaturated group, and a structural unit (M-5) other than the structural units (M-1) to (M-3).

[0051] <<SP value is 20 (J / cm 3 ) 1 / 2 Structural unit (M-3) derived from the following ethylenically unsaturated compound (m-3)≫ The structural unit (M-3) is a structural unit that does not have an ethylenically unsaturated group or a hydroxy group, and has an SP value of 20 (J / cm 3 ) 1 / 2 The structural unit (M-3) is derived from the following ethylenically unsaturated compound. The structural unit (M-3) has an SP value of 20 (J / cm 3 ) 1 / 2 below( It is preferable that the structural unit is derived from a compound having a meth)acryloyloxy group. The unit (M-3) may be of only one type, or of two or more types.

[0052] In this specification, the SP value refers to the solubility parameter value (δTot) calculated using a program called HSPiP (Hansen Solubility Parameters in Practice). δTot represents the magnitude of the HSP vector. The (meth)acrylic resin (A) contains the structural unit (M-3), making it possible to obtain a pressure-sensitive adhesive sheet with good water resistance.

[0053] The content of the structural unit (M-3) in the Y block may be 50 mol% or more, 60 mol% or more, 70 mol% or more, or 80 mol% or more, where the total structural units in the Y block of the (meth)acrylic resin (A) is 100 mol%. The content of the structural unit (M-3) in the Y block may be 80 mol% or less, 90 mol% or less, or 100 mol% or less, where the total structural units in the Y block of the (meth)acrylic resin (A) is 100 mol%. Any combination of these lower and upper limits may be used. From the viewpoint of the water resistance of the pressure-sensitive adhesive composition, the content of the structural unit (M-3) in the Y block is preferably 100 mol%. When the content of the structural unit (M-3) is 50 mol% or more, the hydrophobicity of the Y block of the (meth)acrylic resin (A) is good, and therefore the water resistance of the resulting pressure-sensitive adhesive sheet is good. Therefore, when the pressure-sensitive adhesive sheet is used as a dicing tape or a dicing / die bonding integrated film, the pressure-sensitive adhesive sheet has excellent water resistance even in processes using water such as cutting water, and exhibits good dicing properties. When the content of the structural unit (M-3) is within the above range, the Tg of the Y block of the (meth)acrylic resin (A) can be adjusted to an appropriate range, thereby improving adhesive strength.

[0054] Specific examples of the compound (m-3) that provides the structural unit (M-3) include alkyl (meth)acrylates, styrenes, etc. Examples of alkyl (meth)acrylates include linear or branched alkyl (meth)acrylates having an alkyl group with 1 to 5 carbon atoms, such as methyl (meth)acrylate (18.8, 18.0) and n-butyl (meth)acrylate (19.0, 17.1), linear or branched alkyl (meth)acrylates having an alkyl group with 6 to 30 carbon atoms, such as stearyl (meth)acrylate (16.3, 16.3) and isostearyl (meth)acrylate (16.1, 16.1), cyclopentyl ( Examples include alicyclic skeleton-containing (meth)acrylates such as (meth)acrylate (18.0, 17.6), cyclohexyl (meth)acrylate (18.0, 17.7), ethylcyclohexyl (meth)acrylate (18.2, 17.6), norbornyl (meth)acrylate (18.3, 18.0), dicyclopentanyl (meth)acrylate (17.6, 17.5), isobornyl (meth)acrylate (17.1, 17.0), and adamantyl (meth)acrylate (17.7, 17.5). The numerical value after each compound name is the SP value ((J / cm 3 ) 1 / 2 ) are listed in the order of acrylate and methacrylate. Specific examples of styrenes include styrene (18.3); alkyl derivatives of styrene such as α-methylstyrene (17.8), o-methylstyrene (18.3), m-methylstyrene (18.2), and p-methylstyrene (18.6). The numerical value after each compound name is the SP value ((J / cm 3 ) 1 / 2). Among these, from the viewpoints of reaction control and SP value, at least one selected from the group consisting of linear or branched alkyl (meth)acrylates in which the alkyl group has 6 to 30 carbon atoms, alicyclic skeleton-containing (meth)acrylates, and styrene is preferred, at least one selected from n-butyl acrylate, cyclohexyl acrylate, isostearyl acrylate, and styrene is more preferred, at least one selected from isostearyl acrylate and styrene is even more preferred, and styrene is particularly preferred. Compound (m-3) may be used alone or in combination of two or more.

[0055] <Structural Unit (M-5)> The content of the structural unit (M-5) in the Y block may be 5 mol% or more, 10 mol% or more, or 15 mol% or more, based on 100 mol% of the total structural units in the Y block of the (meth)acrylic resin (A). The content of the structural unit (M-5) in the Y block is preferably 50 mol% or less, more preferably 40 mol% or less, and even more preferably 20 mol% or less, based on 100 mol% of the total structural units in the Y block of the (meth)acrylic resin (A). Any combination of these lower and upper limits is acceptable. When the content of the structural unit (M-5) in the Y block is 5 mol% or more, the Tg of the Y block of the (meth)acrylic resin (A) can be adjusted to an appropriate range, thereby improving adhesive strength. When the content of the structural unit (M-5) in the Y block is 50 mol% or less, the hydrophobicity of the Y block of the (meth)acrylic resin (A) is good, and the resulting pressure-sensitive adhesive sheet has good water resistance. Therefore, when the pressure-sensitive adhesive sheet is used as a dicing tape or a dicing / die bonding integrated film, the pressure-sensitive adhesive sheet has excellent water resistance even in processes using water such as cutting water, and exhibits good dicing properties. From the viewpoint of water resistance, it is preferable that the Y block does not have the structural unit (M-5). The structural unit (M-5) may be of only one type or of two or more types.

[0056] The compound that provides the structural unit (M-5) is, for example, a monomer other than the compounds (m-1) and (m-2) that is copolymerizable with the compound (m-3) and has an SP value of 20 (J / cm 3 ) 1 / 2 Specific examples include carboxyl group-containing monomers, unsaturated dicarboxylic acid diesters, and other vinyl compounds.

[0057] Examples of the carboxyl group-containing monomer include unsaturated monobasic acids such as methacrylic acid, crotonic acid, and acrylic acid substituted with a haloalkyl, alkoxyl, halogen, nitro, or cyano group at the α-position, and unsaturated dibasic acids such as itaconic acid. Among these, methacrylic acid is preferred because of the ease of producing the pressure-sensitive adhesive layer.

[0058] Specific examples of the unsaturated dicarboxylic acid diester include diethyl citraconate, diethyl maleate, diethyl fumarate, and diethyl itaconate.

[0059] Specific examples of other vinyl compounds include (meth)acrylic acid anilide.

[0060] Among these, from the viewpoint of reaction control, the SP value is 20 (J / cm 3 ) 1 / 2 Carboxy group-containing monomers are preferred.

[0061] The (meth)acrylic resin (A) may have at least one selected from the group consisting of the structural unit (M-1) and the structural unit (M-2) in the Y block, as long as the effect is not impaired. Specific examples and suitable examples of the structural units (M-1) and (M-2) in the Y block are the same as those of the structural units (M-1) and (M-2) in the X block.

[0062] When the Y block has the structural unit (M-1), the content of the structural unit (M-1) in the Y block may be 1 mol% or more, 2 mol% or more, or even 5 mol% or more, where the total structural units of the Y block of the (meth)acrylic resin (A) is 100 mol%. When the Y block has the structural unit (M-1), the content of the structural unit (M-1) in the Y block is preferably 15 mol% or less, more preferably 10 mol% or less, and even more preferably 5 mol% or less, where the total structural units of the Y block of the (meth)acrylic resin (A) is 100 mol%, from the viewpoint of improving the water resistance of the PSA sheet. These lower and upper limits may be combined in any combination.

[0063] When the Y block of the (meth)acrylic resin (A) contains the structural unit (M-1), the resin can be sufficiently thermally cured by a crosslinking reaction caused by heating. The resulting adhesive sheet also has good adhesive strength, and when the adhesive sheet is used as a dicing tape or a dicing / die bonding integrated film, it has good dicing properties. Furthermore, the adhesive layer has sufficient strength, preventing contamination of the adherend when the adhesive sheet is peeled off. On the other hand, from the viewpoint of improving water resistance, it is preferable that the Y block of the (meth)acrylic resin (A) does not contain the structural unit (M-1).

[0064] When the Y block of the (meth)acrylic resin (A) has the structural unit (M-2), the content of the structural unit (M-2) in the Y block may be 1 mol % or more, 2 mol % or more, or even 5 mol % or more, based on 100 mol % of the total structural units in the Y block of the (meth)acrylic resin (A). When the Y block has the structural unit (M-2), the content of the structural unit (M-2) in the Y block is preferably 15 mol % or less, more preferably 10 mol % or less, and even more preferably 5 mol % or less, based on 100 mol % of the total structural units in the Y block of the (meth)acrylic resin (A). These lower and upper limits may be combined in any combination. When the Y block of the (meth)acrylic resin (A) has the structural unit (M-2), a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer using this resin is attached to an adherend, and then irradiated with UV light to reduce the adhesive strength and facilitate peeling from the adherend. When used as a dicing tape or a dicing / die bonding integrated film, excellent pickup properties are obtained after UV irradiation. On the other hand, from the viewpoint of improving water resistance, it is preferable that the (meth)acrylic resin (A) does not have the structural unit (M-2) in the Y block.

[0065] <Photopolymerization initiator (B)> Examples of the photopolymerization initiator (B) include benzophenone, benzil, benzoin, ω-bromoacetophenone, chloroacetone, acetophenone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, p-dimethylaminoacetophenone, p-dimethylaminopropiophenone, 2-chlorobenzophenone, 4,4'-dichlorobenzophenone, 4,4'-bisdiethylaminobenzophenone, Michler's ketone, benzoin methyl ether, and benzoin isopropyl alcohol. butyl ether, benzoin-n-butyl ether, benzyl methyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, methylbenzoyl formate, 4'-dimethylaminoacetophenone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, and other carbonyl-based photopolymerization initiators.

[0066] Examples of the photopolymerization initiator (B) include sulfide-based photopolymerization initiators such as diphenyl disulfide, dibenzyl disulfide, tetraethylthiuram disulfide, and tetramethylammonium monosulfide; acylphosphine oxides such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide and 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide; quinone-based photopolymerization initiators such as benzoquinone and anthraquinone; sulfochloride-based photopolymerization initiators; and thioxanthone-based photopolymerization initiators such as thioxanthone, 2-chlorothioxanthone, and 2-methylthioxanthone.

[0067] Among these photopolymerization initiators (B), from the viewpoint of solubility in the pressure-sensitive adhesive composition, carbonyl-based photopolymerization initiators and acylphosphine oxides are preferred, and it is more preferred to use at least one selected from 1-hydroxycyclohexyl phenyl ketone and 2,4,6-trimethylbenzoyldiphenylphosphine oxide.

[0068] The photopolymerization initiator (B) may be used alone or in combination of two or more kinds.

[0069] The amount of the photopolymerization initiator (B) is preferably 0.1 to 5.0 parts by mass, more preferably 0.3 to 2.0 parts by mass, per 100 parts by mass of the (meth)acrylic resin (A). When the content of the photopolymerization initiator (B) per 100 parts by mass of the (meth)acrylic resin (A) is 0.1 part by mass or more, the crosslinking density of the photocrosslinkable pressure-sensitive adhesive (i.e., the thermoset product of the pressure-sensitive adhesive composition) can be improved at a sufficiently fast curing rate upon UV irradiation. Therefore, when the photocrosslinkable pressure-sensitive adhesive is used in the pressure-sensitive adhesive layer, the adhesive strength of the pressure-sensitive adhesive layer after UV irradiation can be sufficiently reduced. When the content of the photopolymerization initiator (B) per 100 parts by mass of the (meth)acrylic resin (A) is 5.0 parts by mass or less, the adhesive strength and water resistance of the pressure-sensitive adhesive layer before UV irradiation can be sufficiently maintained. Even if the content of the photopolymerization initiator (B) exceeds 5.0 parts by mass relative to 100 parts by mass of the (meth)acrylic resin (A), no effect commensurate with the content of the photopolymerization initiator (B) is observed. Therefore, by setting the content to 5.0 parts by mass or less, the pressure-sensitive adhesive composition can be produced economically.

[0070] <Crosslinking agent (C)> The crosslinking agent (C) is a compound that does not have an ethylenically unsaturated bond and has two or more functional groups that react with the hydroxy groups contained in the (meth)acrylic resin (A). The functional groups of the crosslinking agent (C) react with the hydroxy groups of the (meth)acrylic resin (A) by heating, thereby curing the adhesive composition and obtaining a photocrosslinkable adhesive. When a photocrosslinkable adhesive is used in the adhesive layer, an adhesive sheet with a good balance between adhesive strength before and after UV irradiation can be obtained.

[0071] Examples of functional groups that are reactive with hydroxy groups and that the crosslinking agent (C) has include an isocyanato group, an epoxy group, a carboxy group, an acid anhydride group, and an aziridinyl group. From the viewpoint of reactivity, an isocyanato group and an epoxy group are preferred, and an isocyanato group is particularly preferred.

[0072] Examples of the crosslinking agent (C) include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hydrogenated tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane-4,4'-diisocyanate, isophorone diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, isocyanurate of hexamethylene diisocyanate, tetramethylxylylene diisocyanate, 1,5-naphthalene diisocyanate, and tolylene diisocyanate of trimethylolpropane. Polyisocyanates such as methyl ether adducts, xylylene diisocyanate adducts of trimethylolpropane, triphenylmethane triisocyanate, methylene bis(4-phenylmethane) triisocyanate; 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, bisphenol A-epichlorohydrin type epoxy resins, N,N'-[1,3-phenylenebis(methylene)]bis[bis(oxiran-2-ylmethyl)amine], ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglyceride Polyepoxy compounds such as glycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, and diglycerol polyglycidyl ether; hexamethoxymethylmelamine, hexaethoxymethylmelamine, hexapropoxymethylmelamine, hexabutoxymethylmelamine, hexapentyloxymethylmelamine, and hexahexyloxymethylmelamine. Melamine compounds such as dimethylmelamine; ethylene glycol-bis-[3-(2-aziridinyl)propionate], trimethylolpropane-tris[3-(2-aziridinyl)propionate], trimethylolpropane-tris[3-(1-aziridinyl)propionate], trimethylolpropane-tris[3-(2-methyl-1-aziridinyl)propionate], tetramethylolmethane-tris[3-(2-aziridinyl)propionate], pentaerythritol-tris[3-(1-aziridinyl)propionate], N,N'-difluoromethylpropane Examples thereof include aziridinyl compounds such as phenylmethane-4,4'-bis(1-aziridinecarboxamide) and N,N'-hexamethylene-1,6-bis(1-aziridinecarboxamide).

[0073] Among these crosslinking agents (C), it is preferable to use at least one selected from the group consisting of polyisocyanates and polyepoxy compounds, and it is more preferable to use polyisocyanates, because they have good reactivity with the (meth)acrylic resin (A).

[0074] The crosslinking agent (C) may be used alone or in combination of two or more kinds.

[0075] The content of the crosslinking agent (C) is preferably 0.1 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, even more preferably 0.1 to 10 parts by mass, and even more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the (meth)acrylic resin (A). When the content of the crosslinking agent (C) per 100 parts by mass of the (meth)acrylic resin (A) is 0.1 parts by mass or more, a three-dimensional crosslinked structure is sufficiently formed in the photocrosslinkable pressure-sensitive adhesive upon UV irradiation. Therefore, when the photocrosslinkable pressure-sensitive adhesive is used as a pressure-sensitive adhesive, the adhesive strength of the pressure-sensitive adhesive after UV irradiation can be sufficiently reduced. When the content of the crosslinking agent (C) per 100 parts by mass of the (meth)acrylic resin (A) is 30 parts by mass or less, the photocrosslinkable pressure-sensitive adhesive and the cured product after UV irradiation have a good balance of properties, and when used as a dicing tape or a dicing / die-bonding integrated film, the pressure-sensitive adhesive exhibits good adhesive strength and water resistance. When the photocrosslinkable pressure-sensitive adhesive is used as a pressure-sensitive adhesive, the adhesive strength of the pressure-sensitive adhesive before UV irradiation is good.

[0076] <Other ingredients> The pressure-sensitive adhesive composition may contain other components, as needed, in addition to the (meth)acrylic resin (A), the photopolymerization initiator (B), and the crosslinking agent (C), such as a tackifier, a solvent, and various additives.

[0077] (tackifier) Any conventionally known tackifier can be used without any particular limitation. Examples of tackifiers include terpene-based tackifier resins, phenol-based tackifier resins, rosin-based tackifier resins, aliphatic petroleum resins, aromatic petroleum resins, copolymer-based petroleum resins, alicyclic petroleum resins, xylene resins, epoxy-based tackifier resins, polyamide-based tackifier resins, ketone-based tackifier resins, and elastomer-based tackifier resins. These tackifiers may be used alone or in combination of two or more.

[0078] When a tackifier is used, the content of the tackifier in the pressure-sensitive adhesive composition is preferably 30 parts by mass or less, more preferably 5 to 20 parts by mass, per 100 parts by mass of the (meth)acrylic resin (A).

[0079] (solvent) The solvent can be used to dilute the PSA composition in order to adjust the viscosity of the PSA composition. For example, when the PSA composition is applied, the solvent can be used to adjust the viscosity of the PSA composition to an appropriate level. The solvent used in synthesizing the (meth)acrylic resin (A) may be used as is, or a solvent may be added to the solvent.

[0080] Examples of the solvent that can be used include organic solvents such as methyl ethyl ketone, methyl isobutyl ketone, acetone, ethyl acetate, propyl acetate, butyl acetate, tetrahydrofuran, dioxane, cyclohexanone, hexane, toluene, xylene, n-propanol, isopropyl alcohol, etc. These solvents may be used alone or in combination of two or more.

[0081] (additives) Examples of additives include plasticizers, surface lubricants, leveling agents, softeners, antioxidants, antiaging agents, light stabilizers, ultraviolet absorbers, polymerization inhibitors, benzotriazole-based light stabilizers and the like, phosphate ester-based and other flame retardants, surfactants, and antistatic agents.

[0082] [Method for producing (meth)acrylic resin (A)] The (meth)acrylic resin (A) can be produced, for example, by a process comprising: step (i-1) polymerizing the raw material monomers (mX) constituting the X block via reversible addition-fragmentation chain transfer (RAFT); step (i-2) polymerizing the raw material monomers (mY) constituting the Y block via reversible addition-fragmentation chain transfer (RAFT); and, if necessary, step (ii) introducing ethylenically unsaturated groups by adding an ethylenically unsaturated compound having a functional group such as an isocyanato group to some of the hydroxy groups of the copolymer obtained by steps (i-1) and (i-2). The order of steps (i-1) and (i-2) for synthesizing each block is not particularly limited, but it is preferable to perform step (i-2) before step (i-1). Exemplary embodiments of steps (i-1), (i-2), and (ii) are described below.

[0083] <Process (i-1)> Step (i-1) is a step of RAFT polymerization of raw material monomers (mX) containing an ethylenically unsaturated compound (m-1) having a hydroxy group, optionally a (meth)acrylate (m-2) having an ethylenically unsaturated group other than a (meth)acryloyloxy group, and optionally other monomers other than compounds (m-1) and (m-2) in the presence of a reversible addition-fragmentation chain transfer agent (RAFT agent). In this specification, RAFT polymerization refers to radical polymerization carried out in the presence of a RAFT agent. RAFT polymerization is a type of living radical polymerization. Living radical polymerization is generally known as a polymerization method that can produce polymers with narrow molecular weight distributions. Specific examples include atom transfer radical polymerization, organotellurium-mediated radical polymerization, and RAFT polymerization. Of these, RAFT polymerization is suitable for pressure-sensitive adhesive applications.

[0084] The weight-average molecular weight of each block obtained in steps (i-1) and (i-2) can be controlled, for example, by adjusting the amount of radical polymerization initiator and RAFT agent used. By controlling the weight-average molecular weight of each block, the structural unit ratio (molar ratio) of the X block and the Y block can be controlled within a desired range.

[0085] The reaction temperature can be appropriately set depending on the type of radical polymerization initiator used, etc. The reaction temperature is preferably 40 to 125°C, more preferably 60 to 120°C. The reaction time can be appropriately set depending on the type of radical polymerization initiator used, etc. The reaction time is preferably 5 to 24 hours, more preferably 10 to 15 hours.

[0086] The polymerization method may be a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, a suspension polymerization method, an alternating copolymerization method, etc. Among these polymerization methods, in consideration of the addition reaction in step (ii), it is preferable to use a solution polymerization method from the viewpoint of ease of reaction.

[0087] The total concentration of components excluding the solvent in the solution polymerization is preferably 30 to 90% by mass, more preferably 50 to 80% by mass, from the viewpoint of the polymerization rate of the raw material monomer group (mX). Since steps (i-1) and (i-2) are RAFT polymerizations, the polymerization proceeds by an equilibrium reaction. Therefore, the polymerization proceeds very gently, and polymerization can be performed at a high concentration.

[0088] (Reversible Addition-Fragmentation Chain Transfer Agents (RAFT Agents)) Any known RAFT agent can be used without particular limitation, as long as it is a type that allows the polymer to grow in one direction starting from a thiocarbonylthio group. Examples of RAFT agents include trithiocarbonates, dithioesters, dithiocarbonates, and dithiocarbamates. When polymerization is carried out in the presence of these RAFT agents, radical species undergo a chain reaction between the sulfur atom in the RAFT agent and the carbon atom adjacent to that sulfur atom, resulting in polymerization. Among these, trithiocarbonates are preferred because they increase the polymerization reaction rate and conversion rate due to the large transfer constant, and tend to narrow the molecular weight distribution. Symmetric trithiocarbonates cannot be used because the polymer grows in two directions starting from the trithiocarbonate moiety. Therefore, when polymerization is carried out in the order of step (i-1) followed by step (i-2), an XYX triblock copolymer is formed, whereas when polymerization is carried out in the order of step (i-2) followed by step (i-1), a YXY triblock copolymer is formed.

[0089] Specific examples of RAFT agents include sulfur-based compounds (trithiocarbonates, dithioesters, dithiocarbonates, and dithiocarbamates) represented by the following formula (1), formula (2), formula (3), or formula (4).

[0090] Trithiocarbonate [ka] (In formula (1), R 1a and R 1b each independently represents a hydrogen atom, a hydrocarbon group, a carboxy group, or a cyano group; R 1c represents a cyano group, a saturated or unsaturated aliphatic hydrocarbon group which may be substituted with a cyano group or a carboxy group, or a phenyl group which may be substituted; R 2represents a saturated or unsaturated aliphatic hydrocarbon group in which some of the hydrogen atoms may be substituted with a carboxy group, or a benzyl group in which some of the hydrogen atoms may be substituted with a substituted carbamoyl group, an alkoxycarbonyl group having 2 to 5 carbon atoms which may be substituted with a hydroxy group, or an alkenyloxycarbonyl group having 3 to 5 carbon atoms, provided that (R 1a )(R 1b )(R 1c ) C and R 2 are different.)

[0091] Dithioesters [ka] (In formula (2), R 3a and R 3b each independently represents a hydrogen atom, a hydrocarbon group, or a cyano group; R 3c represents a carboxy group, an acetoxymethyl group, or a hydrocarbon group which may be substituted with a cyano group or a carboxy group; R 4 represents a hydrocarbon group.

[0092] Dithiocarbonate [ka] (In formula (3), R 5a and R 5b each independently represents a hydrogen atom, a hydrocarbon group, a carboxy group which may be substituted with a saturated aliphatic hydrocarbon group having 1 to 3 carbon atoms, or a cyano group; R 5c represents a hydrocarbon group which may be substituted with an alkoxy group, and R 6 represents a hydrocarbon group.

[0093] Dithiocarbamate [ka] (In formula (4), R 7a and R 7b each independently represents a hydrogen atom or a hydrocarbon group, R 7crepresents a cyano group, and R 8 and R 9 each independently represents a hydrocarbon group, or R 8 and R 9 may be bonded to form a saturated aliphatic hydrocarbon group having 1 to 3 carbon atoms or a pyrazole ring which may be substituted with a chlorine atom.)

[0094] In formula (1), R 1a and R 1b Examples of the hydrocarbon group represented by the formula (1) include linear, branched, or cyclic, saturated or unsaturated hydrocarbon groups having 1 to 20 carbon atoms, and among these, linear, branched, or cyclic, saturated or unsaturated hydrocarbon groups having 1 to 12 carbon atoms are preferred. Examples of the hydrocarbon group include linear, branched, or cyclic saturated aliphatic hydrocarbon groups having 1 to 20 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclohexyl, undecyl, dodecyl, and octadecyl; aryl groups having 6 to 12 carbon atoms, such as phenyl; and arylalkyl groups having 7 to 10 carbon atoms, such as benzyl and phenethyl. In formula (1), R 1c Examples of the saturated or unsaturated aliphatic hydrocarbon group represented by the formula (1) include linear, branched, or cyclic, saturated or unsaturated aliphatic hydrocarbon groups having 1 to 20 carbon atoms, and among these, linear, branched, or cyclic, saturated or unsaturated aliphatic hydrocarbon groups having 1 to 12 carbon atoms are preferred. Examples of the aliphatic hydrocarbon group include linear, branched, or cyclic, saturated aliphatic hydrocarbon groups having 1 to 20 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclohexyl, undecyl, dodecyl, and octadecyl groups. In formula (1), R 1c For example, 1 to 3 hydrogen atoms of the saturated or unsaturated aliphatic hydrocarbon group represented by the formula (1) may be substituted with a carboxy group or a cyano group, and the carboxy group may be further substituted with a saturated aliphatic hydrocarbon group having 1 to 3 carbon atoms. 1cExamples of the substituent of the optionally substituted phenyl group represented by the formula (1) include a substituted carbamoyl group, an alkoxycarbonyl group having 2 to 5 carbon atoms which may be substituted with a hydroxy group, and an alkenyloxycarbonyl group having 3 to 5 carbon atoms. Examples of the substituent of the substituted carbamoyl group include a saturated aliphatic hydrocarbon group having 1 to 3 carbon atoms which may be substituted with a hydroxy group or an acetyloxy group. In formula (1), R 2 Examples of the saturated or unsaturated aliphatic hydrocarbon group represented by the formula (1) include linear, branched, or cyclic saturated or unsaturated aliphatic hydrocarbon groups having 1 to 20 carbon atoms, and among these, aliphatic hydrocarbon groups having 1 to 12 carbon atoms are preferred. Examples of the aliphatic hydrocarbon group include linear, branched, or cyclic saturated aliphatic hydrocarbon groups having 1 to 20 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclohexyl, dodecyl, and octadecyl groups. In formula (1), R 2 In formula (1), for example, 1 to 3 of the hydrogen atoms of the saturated or unsaturated aliphatic hydrocarbon group represented by the formula (1) may be substituted with a carboxy group. 2 Examples of the substituent of the substituted carbamoyl group of the optionally substituted benzyl group represented by the formula (I) include saturated aliphatic hydrocarbon groups having 1 to 3 carbon atoms which may be substituted with a hydroxy group or an acetyloxy group. 1a and R 1b are each independently a hydrogen atom, a hydrocarbon group having 1 to 4 carbon atoms, a carboxy group, or a cyano group, and R 1c is an undecyl group, a hydrocarbon group having 1 to 4 carbon atoms which may be substituted with a carboxy group, or a phenyl group which may be substituted, and R 2 is a linear, branched or cyclic, saturated or unsaturated aliphatic hydrocarbon group having 1 to 20 carbon atoms, or an optionally substituted benzyl group, and 1a and R 1b is a hydrogen atom, a combination of a methyl group or an ethyl group with a cyano group or a carboxy group, or a hydrogen atom, and R 1cis a methyl group, an ethyl group, an undecyl group, or an optionally substituted phenyl group, and R 2 is a linear saturated aliphatic hydrocarbon group having 1 to 20 carbon atoms, or a benzyl group in which some of the hydrogen atoms may be substituted with a substituted carbamoyl group, an alkoxycarbonyl group having 2 to 5 carbon atoms which may be substituted with a hydroxy group, or an alkenyloxycarbonyl group having 3 to 5 carbon atoms, is more preferred.

[0095] In formula (2), R 3a , R 3b , R 3c and R 4 Examples of the hydrocarbon group represented by the formula (2) include linear, branched, or cyclic, saturated or unsaturated hydrocarbon groups having 1 to 20 carbon atoms, and among these, linear, branched, or cyclic, saturated or unsaturated hydrocarbon groups having 1 to 12 carbon atoms are preferred. Examples of the hydrocarbon group include linear, branched, or cyclic saturated aliphatic hydrocarbon groups having 1 to 20 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclohexyl, dodecyl, and octadecyl; aryl groups having 6 to 12 carbon atoms, such as phenyl; and arylalkyl groups having 7 to 10 carbon atoms, such as benzyl and phenethyl. In formula (2), R 3c Examples of the hydrocarbon group represented by the formula (I) which may be substituted with a cyano group or a carboxy group include the above-mentioned hydrocarbon group in which 1 to 3 hydrogen atoms have been substituted with a cyano group or a carboxy group. 3a and R 3b are each independently a linear saturated hydrocarbon group having 1 to 4 carbon atoms, and R 3c is an aryl group, and R 4 is an aryl group or a benzyl group, and 3a and R 3 b are each independently a methyl group or an ethyl group, and R 3c is a phenyl group, and R 4 More preferred are compounds of formula (2) in which is a phenyl group or a benzyl group.

[0096] In formula (3), R 5a , R 5b , R 5c and R 6 Examples of the hydrocarbon group represented by the formula (3) include linear, branched, or cyclic, saturated or unsaturated hydrocarbon groups having 1 to 20 carbon atoms, and among these, linear, branched, or cyclic, saturated or unsaturated hydrocarbon groups having 1 to 12 carbon atoms are preferred. Examples of the hydrocarbon group include linear, branched, or cyclic saturated aliphatic hydrocarbon groups having 1 to 20 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclohexyl, dodecyl, and octadecyl; aryl groups having 6 to 12 carbon atoms, such as phenyl; and arylalkyl groups having 7 to 10 carbon atoms, such as benzyl and phenethyl. In formula (3), R 5c Examples of the hydrocarbon group which may be substituted with an alkoxy group include the above hydrocarbon groups in which 1 to 3 hydrogen atoms have been substituted with alkoxy groups.

[0097] In formula (4), R 7a , R 7b , R 8 and R 9 Examples of the hydrocarbon group represented by the formula (R) include linear, branched, or cyclic, saturated or unsaturated hydrocarbon groups having 1 to 20 carbon atoms, and among these, linear, branched, or cyclic, saturated or unsaturated hydrocarbon groups having 1 to 12 carbon atoms are preferred. Examples of the hydrocarbon group include linear, branched, or cyclic saturated aliphatic hydrocarbon groups having 1 to 20 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclohexyl, dodecyl, and octadecyl; aryl groups having 6 to 12 carbon atoms, such as phenyl; and arylalkyl groups having 7 to 10 carbon atoms, such as benzyl and phenethyl. 8 and R 9 may form a pyrazole ring together with the nitrogen atom of formula (4), and the pyrazole ring may be substituted with a saturated aliphatic hydrocarbon group having 1 to 3 carbon atoms or a chlorine atom.

[0098] Many RAFT agents are commercially available, and those that are not commercially available can be readily synthesized by known or conventional methods.

[0099] Specific examples of RAFT agents include S-cyanomethyl-S-dodecyltrithiocarbonate, 2-[(dodecylsulfanylthiocarbonyl)sulfanyl]propanoic acid, 2-{[(2-carboxyethyl)sulfanylthiocarbonyl]sulfanyl}propanoic acid, 4 Trithiocarbonates such as -[(2-carboxyethylsulfanylthiocarbonyl)sulfanyl]-4-cyanopentanoic acid, 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid, methyl 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoate, 2-cyano-2-propyldodecyltrithiocarbonate, and benzyldodecyl trithiocarbonate; cyanoethyl dithiopropionate, benzyl dithiopropionate, benzyl dithiobenzoate, acetoxyethyl dithiobenzoate, 2-phenyl-2-propyldithiobenzoic acid, 2-cyano-2-propyldithiobenzoic acid, 4-cyano-4-(phenylcarbonothioylthio)pentanoic acid, S-(thio Dithioesters of benzoyl)thioglycolic acid, etc.; ethyl 2-[(ethoxycarbonothioyl)thio]propionate, O-ethyl-S-(2-propoxyethyl)dithiocarbonate dithiocarbonates such as 2-cyano-2-propyldiethyldithiocarbamate, 2'-cyanobutan-2'-yl 4-chloro-3,5-dimethylpyrazole-1-dithiocarbamate, 2'-cyanobutan-2'-yl 3,5-dimethylpyrazole-1-dithiocarbamate, cyanomethyl 3,5-dimethylpyrazole-1-dithiocarbamate, and cyanomethyl N-methyl-N-phenyldithiocarbamate. Among these, from the viewpoint of ease of polymerization of the (meth)acrylic resin (A), trithiocarbonates and dithioesters are preferred, and 2-[(dodecylsulfanylthiocarbonyl)sulfanyl]propanoic acid, 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid, 2-{[(2-carboxyethyl)sulfanylthiocarbonyl]sulfanyl]propanoic acid, 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid, 2-{[(2-carboxyethyl)sulfanylthiocarbonyl]sulfanyl]propanoic acid, 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid, 4-{[(2-carboxyethyl)sulfanylthiocarbonyl]sulfanyl]prop ... More preferred are 2-phenyl-2-propyldithiobenzoic acid, benzyldodecyl trithiocarbonate, and 2-phenyl-2-propyldithiobenzoic acid.

[0100] The RAFT agents may be used alone or in combination of two or more.

[0101] When step (i-2) is carried out before step (i-1), by continuing to use the RAFT agent blended in step (i-2), a diblock copolymer in which a block synthesized from raw material monomer group (mX) is connected to a block synthesized from raw material monomer group (mY) can be obtained.

[0102] The amount of the RAFT agent used is preferably 0.001 to 1.0 part by mass, more preferably 0.005 to 0.5 part by mass, and even more preferably 0.01 to 0.35 part by mass, relative to 100 parts by mass of the total of the raw material monomer group (mX), raw material monomer group (mY), and the optionally used ethylenically unsaturated compound having a functional group such as an isocyanato group. When the amount is 0.001 part by mass or more, polymerization can be performed in an efficient reaction time. When the amount is 1.0 part by mass or less, a block with a sufficiently high molecular weight can be obtained.

[0103] (Radical polymerization initiator) RAFT polymerization is preferably carried out in the presence of a radical polymerization initiator. Examples of the radical polymerization initiator include ordinary organic radical polymerization initiators, specifically, 2,2'-azobis(isobutyronitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis(2,4,4-trimethylpentane), dimethyl-2,2'-azobis and oil-soluble polymerization initiators such as azo-based polymerization initiators such as 2,2'-azobis(N-butyl-2-methylpropionate) and 2,2'-azobis(N-butyl-2-methylpropionamide); and peroxide-based polymerization initiators such as benzoyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, t-butyl peroxybenzoate, dicumyl peroxide, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, and 1,1-bis(t-butylperoxy)cyclododecane.

[0104] Among these radical polymerization initiators, azo-based polymerization initiators are preferred in terms of the 10-hour half-life temperature and solubility in organic solvents, and it is more preferable to use at least one selected from 2,2'-azobis(isobutyronitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylbutyronitrile), and 2,2'-azobis(N-butyl-2-methylpropionamide).

[0105] The radical polymerization initiators may be used alone or in combination of two or more.

[0106] When step (i-2) is carried out before step (i-1), the radical polymerization initiator added in step (i-2) may be continued to be used, or a radical polymerization initiator may be further added in step (i-1) to compensate for the radical polymerization initiator deactivated in step (i-2). From the viewpoints of reactivity and molecular weight control, it is preferable to further add the radical polymerization initiator in step (i-1).

[0107] The amount of radical polymerization initiator added in step (i-1) is preferably 0.0001 to 1.0 part by mass, more preferably 0.001 to 0.5 part by mass, and even more preferably 0.005 to 0.1 part by mass, relative to 100 parts by mass of the total amount of raw material monomer group (mX), raw material monomer group (mY), and optionally, an ethylenically unsaturated compound having a functional group such as an isocyanato group. When the amount is 0.0001 part by mass or more, polymerization can be performed in an efficient reaction time. When the amount is 1.0 part by mass or less, a block with a sufficiently high molecular weight can be obtained.

[0108] The molar ratio of the radicals generated from the radical polymerization initiator added in step (i-1) to the RAFT agent is preferably 1.0:1.0 to 1.0:1.5, from the viewpoint of preferentially proceeding living radical polymerization over free radical polymerization.

[0109] (solvent) The solvent that may be used in step (i-1) may be a common solvent. Examples of the solvent include esters such as ethyl acetate, propyl acetate, and butyl acetate; aromatic hydrocarbons such as toluene, xylene, and benzene; aliphatic hydrocarbons such as hexane and heptane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; ketones such as methyl ethyl ketone and methyl isobutyl ketone; glycols such as ethylene glycol, propylene glycol, and dipropylene glycol; glycol ethers such as methyl cellosolve, propylene glycol monomethyl ether, and dipropylene glycol monomethyl ether; and glycol esters such as ethylene glycol diacetate and propylene glycol monomethyl ether acetate. The solvents may be used alone or in combination of two or more.

[0110] When step (i-2) is carried out before step (i-1), the solvent added in step (i-2) may be used continuously or may be further added in step (i-1).

[0111] <Process (i-2)> In step (i-2), the SP value is 20 (J / cm ) in the presence of a reversible addition-fragmentation chain transfer agent (RAFT agent). 3 ) 1 / 2 This is a step of RAFT polymerization of the following ethylenically unsaturated compound (m-3) and a raw material monomer group (mY) optionally containing a monomer other than (m-3).

[0112] Conditions such as reaction temperature, reaction time, polymerization method, concentration, etc. can be appropriately set in the same manner as in step (i-1).

[0113] The RAFT agent used can be the same as that used in step (i-1), and the preferred RAFT agent is also the same. When step (i-1) is performed before step (i-2), the RAFT agent added in step (i-1) can be subsequently used to obtain a diblock copolymer in which a block synthesized from raw material monomer group (mY) is connected to a block synthesized from raw material monomer group (mX).

[0114] The radical polymerization initiator can be the same as that used in step (i-1), and the preferred radical polymerization initiators are also the same. When step (i-1) is performed before step (i-2), the radical polymerization initiator added in step (i-1) may be continued to be used, or a radical polymerization initiator may be further added in step (i-2) to compensate for the radical polymerization initiator deactivated in step (i-1). From the viewpoints of reactivity and molecular weight control, it is preferable to further add the radical polymerization initiator in step (i-2).

[0115] The amount of radical polymerization initiator added in step (i-2) is preferably 0.0001 to 1.0 part by mass, more preferably 0.001 to 0.5 part by mass, and even more preferably 0.005 to 0.1 part by mass, relative to 100 parts by mass of the total amount of raw material monomer group (mX), raw material monomer group (mY), and optionally, an ethylenically unsaturated compound having a functional group such as an isocyanato group. When the amount is 0.0001 part by mass or more, polymerization can be performed in an efficient reaction time. When the amount is 1.0 part by mass or less, a block with a sufficiently high molecular weight can be obtained.

[0116] The molar ratio of the radicals generated from the radical polymerization initiator added in step (i-2) to the RAFT agent is preferably 1.0:1.0 to 1.0:1.5, from the viewpoint of preferentially proceeding living radical polymerization over free radical polymerization.

[0117] The solvent may be the same as that used in step (i-1). When step (i-1) is performed before step (i-2), the solvent added in step (i-1) may be used continuously or may be further added in step (i-2).

[0118] <Process (ii)> Step (ii) is a step of adding an ethylenically unsaturated compound to some of the side-chain hydroxy groups of the copolymer obtained by steps (i-1) and (i-2) to introduce ethylenically unsaturated groups. If an ethylenically unsaturated compound is added to all of the side-chain hydroxy groups of the copolymer obtained by steps (i-1) and (i-2), the resulting copolymer will no longer contain hydroxy groups, resulting in insufficient adhesive strength as a pressure-sensitive adhesive sheet. In addition, if an ethylenically unsaturated compound is added to all of the side-chain hydroxy groups of the copolymer obtained by steps (i-1) and (i-2), there will be no reaction sites with the crosslinking agent (C) described below. Therefore, addition is limited to some of the side-chain hydroxy groups. Specifically, when the side-chain hydroxy groups are taken as 100 mol%, it is preferable that 40 to 99 mol% of the side-chain hydroxy groups be subjected to the addition reaction. The method of adding the ethylenically unsaturated compound is not particularly limited, and methods known in the technical field of this specification can be used. Since the (meth)acrylic resin (A) has an ethylenically unsaturated group in its side chain, the length of the molecular chain between crosslinking points is relatively short compared to a (meth)acrylic copolymer having an ethylenically unsaturated group introduced at the terminal, and the crosslinking density can be efficiently improved by UV irradiation. Therefore, when the (meth)acrylic resin (A) is used as a pressure-sensitive adhesive material, the adhesive strength after UV irradiation can be significantly reduced. Therefore, a pressure-sensitive adhesive sheet using the (meth)acrylic resin (A) has excellent releasability from an adherend. In addition, a pressure-sensitive adhesive composition produced using the (meth)acrylic resin (A) has excellent adhesion to an adhesive layer. Therefore, a pressure-sensitive adhesive composition produced using the (meth)acrylic resin (A) is suitable for use in a pressure-sensitive adhesive layer of a dicing tape.

[0119] (catalyst) In the addition reaction in step (ii), a known catalyst can be used as needed. Examples of the catalyst used in adding the isocyanato group-containing ethylenically unsaturated compound (a) to the side chain hydroxy group include urethane catalysts such as dibutyltin dilaurate, titanium diisopropoxybis(ethylacetoacetate), tetrakis(2,4-pentanedionato)zirconium, and bismuth tris(2-ethylhexanoate).

[0120] When a catalyst is used in adding the isocyanato group-containing ethylenically unsaturated compound (a) to the side chain hydroxy group in step (ii), the amount of the catalyst used is preferably 0.01 to 10 parts by mass, more preferably 0.02 to 5 parts by mass, and even more preferably 0.03 to 1 part by mass, relative to 100 parts by mass of the copolymer obtained in steps (i-1) and (i-2) and the isocyanato group-containing ethylenically unsaturated compound (a) in total.

[0121] (polymerization inhibitor) In the addition reaction in step (ii), a known polymerization inhibitor can be used as needed. The polymerization inhibitor can be any known one, and is not particularly limited. Examples of the polymerization inhibitor include 4-methoxyphenol, hydroquinone, methoquinone, 2,6-di-t-butylphenol, 2,2'-methylenebis(4-methyl-6-t-butylphenol), and phenothiazine. The polymerization inhibitors can be used alone or in combination of two or more.

[0122] When a polymerization inhibitor is used in step (ii), the amount of the polymerization inhibitor used is preferably 0.005 to 5 parts by mass, more preferably 0.03 to 3 parts by mass, and even more preferably 0.05 to 1.5 parts by mass, relative to 100 parts by mass of the copolymer obtained in steps (i-1) and (i-2) and the ethylenically unsaturated compound combined. When the amount of the polymerization inhibitor used is 0.005 parts by mass or more, gelation during the addition reaction can be prevented. On the other hand, when the amount of the polymerization inhibitor used is 5 parts by mass or less, sufficient exposure sensitivity of the (meth)acrylic resin (A) during UV irradiation can be obtained.

[0123] (Reaction conditions) The temperature of the addition reaction is preferably 25°C to 130°C, and particularly preferably 40°C to 90°C. When the temperature of the addition reaction is 25°C or higher, a sufficient reaction rate can be obtained. When the temperature of the addition reaction is 130°C or lower, crosslinking of double bonds due to thermal radical polymerization can be prevented, preventing the formation of gelled products.

[0124] During the addition reaction, a gas having a polymerization inhibitory effect may be introduced into the reaction system. By introducing a gas having a polymerization inhibitory effect into the reaction system, gelation during the addition reaction can be prevented.

[0125] Examples of gases that have a polymerization-inhibiting effect include gases containing oxygen to an extent that does not fall within the explosive range of the substances in the system, such as air.

[0126] It is more preferable to use a gas having a polymerization inhibitor effect in combination with a polymerization inhibitor, since this allows the amount of polymerization inhibitor used to be reduced and the polymerization inhibitor effect to be enhanced.

[0127] [Method of manufacturing pressure-sensitive adhesive composition] <Step (iii)> The pressure-sensitive adhesive composition can be produced, for example, by a method including step (iii) of mixing a (meth)acrylic resin (A), a photopolymerization initiator (B), a crosslinking agent (C), and other components that are added as needed.

[0128] The method for mixing the components contained in the pressure-sensitive adhesive composition is not particularly limited. Mixing can be carried out using, for example, a stirring device equipped with stirring blades such as a homodisper or a paddle blade.

[0129] [Method for producing photocrosslinkable adhesive] <Process (iv)> The photocrosslinkable pressure-sensitive adhesive can be produced, for example, by a method including a step (iv) of applying a pressure-sensitive adhesive composition onto a substrate or a release sheet and thermally curing the composition.

[0130] The pressure-sensitive adhesive composition obtained in step (iii) may be used as is, or a solvent may be further added to adjust the viscosity before use.

[0131] The thermal curing proceeds by optionally carrying out heat drying and curing during the process of forming the photocrosslinkable pressure-sensitive adhesive. For example, in one embodiment of step (iv), the pressure-sensitive adhesive composition is applied to a substrate, and if a solvent is contained, the applied composition is heated and dried to remove the solvent, thereby forming a pressure-sensitive adhesive composition layer. Thereafter, a release sheet is attached to the pressure-sensitive adhesive composition layer as needed. Furthermore, the obtained sheet is optionally cured in an oven for a certain period of time to form a crosslinked structure, thereby obtaining a photocrosslinkable pressure-sensitive adhesive layer.

[0132] According to another embodiment, step (iv) includes step (iv-1) of applying a pressure-sensitive adhesive composition to a release sheet to obtain a pressure-sensitive adhesive composition layer, step (iv-2) of thermally curing the pressure-sensitive adhesive composition layer to obtain a photocrosslinkable pressure-sensitive adhesive layer, and step (iv-3) of laminating a substrate on the pressure-sensitive adhesive composition layer or the photocrosslinkable pressure-sensitive adhesive layer. Step (iv-3) may be performed between step (iv-1) and step (iv-2), or may be performed after step (iv-2). For example, the pressure-sensitive adhesive composition is applied to a release sheet, and if a solvent is contained, the applied composition is heated and dried to remove the solvent, thereby forming a pressure-sensitive adhesive composition layer (step (iv-1)). Thereafter, the release sheet having the pressure-sensitive adhesive composition layer is placed on a substrate with the surface of the pressure-sensitive adhesive composition layer facing the substrate, and the pressure-sensitive adhesive composition layer is transferred onto the substrate (step (iv-3)). Furthermore, if necessary, the obtained sheet may be cured in an oven for a certain period of time to form a crosslinked structure, thereby obtaining a photocrosslinkable pressure-sensitive adhesive layer (step (iv-2)).

[0133] The pressure-sensitive adhesive composition can be applied to a substrate or a release sheet by any known method, specifically, by using a conventional coater such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, a spray coater, a comma coater, or a direct coater.

[0134] The conditions for heat-drying the applied pressure-sensitive adhesive composition are not particularly limited, but are typically 25 to 180°C, preferably 60 to 150°C, for 1 to 20 minutes, preferably 1 to 10 minutes. Heat-drying within the above ranges allows the solvent contained in the pressure-sensitive adhesive composition to be removed. The conditions for curing the heat-dried sheet in an oven for a certain period of time are not particularly limited, but are typically 25 to 100°C, preferably 30 to 80°C, for 1 to 30 days, preferably 1 to 14 days. Curing under the above conditions allows the (meth)acrylic resin (A) to be crosslinked by the crosslinking agent (C), thereby adjusting the gel fraction of the photocrosslinkable pressure-sensitive adhesive to the desired range.

[0135] [Adhesive sheet] The pressure-sensitive adhesive sheet has a base layer and a pressure-sensitive adhesive layer made of a thermoset or photothermally cured product of the pressure-sensitive adhesive composition. Before being attached to an adherend, the pressure-sensitive adhesive sheet may have a release sheet on the exposed surface of the pressure-sensitive adhesive layer (i.e., the surface opposite the base layer), if necessary. The pressure-sensitive adhesive sheet can be obtained, for example, by step (iv). When attached to an adherend, the pressure-sensitive adhesive layer is used in the form of a photocrosslinkable pressure-sensitive adhesive layer, and when peeling from the adherend, the photocrosslinkable pressure-sensitive adhesive layer is irradiated with UV light to crosslink the layer, thereby reducing its adhesive strength, before being peeled off.

[0136] The substrate is not particularly limited and can be selected appropriately depending on the application. Resin films are generally preferred, and examples of resin materials include polyvinyl chloride, polyvinylidene chloride, polyolefins (PO), polyesters, polyurethanes, polycarbonates, polyether ether ketones, polyimides, polyetherimides, polyamides, wholly aromatic polyamides (aramids), polyphenylene sulfide, fluororesins, cellulose-based resins, and silicone resins. Examples of polyolefins include polyethylenes (PE), such as low-density polyethylene, linear polyethylene, medium-density polyethylene, high-density polyethylene, and ultra-low-density polyethylene; polypropylenes (PP), such as random copolymer polypropylene, block copolymer polypropylene, and homopolypropylene; polybutene; polymethylpentene; ethylene-vinyl acetate copolymers; ionomer resins; ethylene-(meth)acrylic acid copolymers; ethylene-(meth)acrylic acid ester copolymers; ethylene-butene copolymers; and ethylene-hexene copolymers. Examples of polyesters include polyethylene terephthalate (PET), polyethylene naphthalate, and polybutylene terephthalate (PBT). Among these resin materials, it is preferable to use one or more selected from the group consisting of PE, PP, and PET, since this allows the production of a pressure-sensitive adhesive sheet with appropriate flexibility. The resin material used as the substrate material may be a single material or a mixture of two or more materials. When used as a dicing tape, it is preferable to use polyolefin.

[0137] The substrate may be made of one type of material or two or more types of materials. The substrate may have a single-layer structure or a multi-layer structure. Since the photocrosslinkable pressure-sensitive adhesive on the substrate is UV-curable, it is preferable that the substrate is UV-transparent. When the substrate is a resin film, the substrate may be a non-stretched film, a uniaxially stretched film, or a biaxially stretched film.

[0138] The substrate may be subjected to a treatment to enhance adhesion, such as a physical treatment such as corona discharge treatment, plasma treatment, sand matting treatment, ozone exposure treatment, flame exposure treatment, high-voltage shock exposure treatment, or ionizing radiation treatment, a chemical treatment such as chromate treatment, or a primer treatment.

[0139] It is preferable to use a PO film as the substrate. PO film has low heat resistance and is not suitable for the above-mentioned heat drying temperature. Therefore, it is preferable to apply the pressure-sensitive adhesive composition to a release sheet, heat-dry to remove the solvent, and then transfer the pressure-sensitive adhesive composition layer to the PO film. Specifically, it is preferable to apply the pressure-sensitive adhesive composition to the release-treated surface of a silicone-based light-release PET film, heat-dry, and then attach the PO film to the pressure-sensitive adhesive composition layer using a rubber roller so that the corona-treated surface of the PO film adheres to the exposed surface of the pressure-sensitive adhesive composition layer.

[0140] The release sheet is not particularly limited, and for example, a sheet generally used for pressure-sensitive adhesives can be used without any restrictions. Specifically, the same resin film as that used for the substrate is preferred, and from the viewpoint of handling, it is preferred to use a resin film containing one or more selected from PE, PP, and PET.

[0141] The release sheet may be subjected to a release treatment to impart easy releasability, specifically, a silicone release treatment or the like.

[0142] The thickness of the photocrosslinkable pressure-sensitive adhesive layer is preferably 5 to 100 μm, more preferably 10 to 50 μm, and even more preferably 10 to 20 μm. If the thickness of the photocrosslinkable pressure-sensitive adhesive layer is 5 μm or more, sufficient adhesive properties are exhibited and coating is easy. If the thickness of the photocrosslinkable pressure-sensitive adhesive layer is 100 μm or less, the generation of bubbles during heat drying and residual solvent can be suppressed.

[0143] [Uses of adhesive sheets] The pressure-sensitive adhesive sheet can be used as a removable pressure-sensitive adhesive sheet, for example, when manufacturing electronic components. Specifically, the removable pressure-sensitive adhesive sheet can be used as a surface protection tape to protect the surface of an adherend in each process of manufacturing electronic components. The pressure-sensitive adhesive sheet can also be used in each process of manufacturing electronic components, fixing an adherend and subjecting it to various processing steps before being detached from the adherend by irradiating it with UV (ultraviolet) light. Therefore, the pressure-sensitive adhesive sheet can be used as a backgrinding tape, dicing tape, dicing / die bonding integrated film, etc. when processing semiconductor wafers. The pressure-sensitive adhesive sheet can also be used as a support tape for fragile materials such as ultrathin glass substrates and materials prone to warping such as FPC boards. In particular, the pressure-sensitive adhesive sheet has excellent water resistance and sufficient adhesive strength to the adherend, making it suitable for dicing tape and dicing / die bonding integrated film.

[0144] [Dicing tape] The dicing tape has a base layer and an adhesive layer made of a thermoset or photo-cured adhesive composition.

[0145] An exemplary method of using the adhesive sheet as a wafer dicing tape is described below. Before the dicing process, an adhesive sheet is attached to a wafer on which multiple components are formed. Next, the wafer is cut and separated (diced) into individual components to form small device pieces (chips). Then, the adhesive sheet attached to each small device piece is irradiated with UV light. This causes UV to be irradiated onto the photocrosslinkable adhesive layer through the base material of the adhesive sheet, and the unsaturated bonds in the photocrosslinkable adhesive form a three-dimensional crosslinked structure and harden. As a result, the adhesive strength of the adhesive layer is reduced. Then, the adhesive sheet is peeled off from each small device piece.

[0146] [Dicing tape manufacturing method] The dicing tape can be produced, for example, by forming a photocrosslinkable pressure-sensitive adhesive layer on a substrate. The photocrosslinkable pressure-sensitive adhesive layer can be formed, for example, by a method similar to that of the above-mentioned step (iv).

[0147] The substrate is preferably made of a material suitable for the expanding process, and is preferably a polyolefin film.

[0148] When a polyolefin film is used, heating during the formation of the photocrosslinkable pressure-sensitive adhesive layer may cause problems in terms of heat resistance. a step (iv-1) of applying the pressure-sensitive adhesive composition onto a release sheet to obtain a pressure-sensitive adhesive composition layer; a step (iv-2) of thermally curing the pressure-sensitive adhesive composition layer to obtain a photocrosslinkable pressure-sensitive adhesive layer; a step (iv-3) of laminating a substrate on the photocrosslinkable pressure-sensitive adhesive layer; It is preferable to carry out the above steps in this order, and then cure the resulting sheet in an oven for a certain period of time as necessary to form a crosslinked structure, thereby obtaining a dicing tape.

[0149] The thickness of the photocrosslinkable pressure-sensitive adhesive layer is preferably 5 to 100 μm, more preferably 10 to 50 μm, and even more preferably 10 to 20 μm. When the thickness of the photocrosslinkable pressure-sensitive adhesive layer is 5 μm or more, sufficient adhesive properties are exhibited and coating is easy. When the thickness of the photocrosslinkable pressure-sensitive adhesive layer is 100 μm or less, the generation of bubbles during heat drying and residual solvent can be suppressed. In particular, when the thickness of the photocrosslinkable pressure-sensitive adhesive layer is 10 to 20 μm, sufficient peelability and severability (cuttability) can be obtained.

[0150] [Dicing and die bonding integrated film] The dicing-die bonding integrated film has, in this order, a base layer, a pressure-sensitive adhesive layer made of a thermosetting or photothermally cured pressure-sensitive adhesive composition, and an adhesive layer.

[0151] [Manufacturing method for integrated dicing and die bonding film] The dicing and die bonding integrated film can be obtained, for example, by laminating a dicing tape and a die bonding tape. The dicing tape can be produced, for example, by a method similar to the above-mentioned production method.

[0152] An example of a method for producing a dicing / die bonding integrated film includes the following steps. a step (iv-1) of applying the pressure-sensitive adhesive composition onto a release sheet to obtain a pressure-sensitive adhesive composition layer; a step (iv-2) of thermally curing the pressure-sensitive adhesive composition layer to obtain a photocrosslinkable pressure-sensitive adhesive layer; a step (iv-3) of laminating a substrate on the pressure-sensitive adhesive composition layer or the photocrosslinkable pressure-sensitive adhesive layer to obtain a dicing tape; Step (v) of laminating the dicing tape and the die bonding tape. The order of the steps may be reversed, except that step (iv-1) is performed first and step (v) is performed last. Step (iv-3) may be performed between step (iv-1) and step (iv-2), or after step (iv-2).

[0153] The thickness of the photocrosslinkable pressure-sensitive adhesive layer is preferably 5 to 100 μm, more preferably 10 to 50 μm, and even more preferably 10 to 20 μm. When the thickness of the photocrosslinkable pressure-sensitive adhesive layer is 5 μm or more, sufficient adhesive properties are exhibited and coating is easy. When the thickness of the photocrosslinkable pressure-sensitive adhesive layer is 100 μm or less, the generation of bubbles during heat drying and residual solvent can be suppressed. In particular, when the thickness of the photocrosslinkable pressure-sensitive adhesive layer is 10 to 20 μm, sufficient peelability and severability (cuttability) can be obtained.

[0154] Step (v) can be performed, for example, by preparing a die bonding tape and bonding it to a dicing tape. The die bonding tape can be obtained, for example, by applying an adhesive composition to a release sheet and curing it to form an adhesive layer. The bonding temperature is, for example, 30 to 50°C. The bonding pressure (linear pressure) is, for example, 0.1 to 20 kgf / cm.

[0155] As a modified example of the method for producing a dicing-die bonding integrated film, the thermal curing of the pressure-sensitive adhesive composition may be carried out in two steps, step (iv-2) and step (v). For example, after the thermal curing is advanced in step (iv-2), the dicing tape and the die bonding tape may be laminated together in step (v), followed by curing to further advance the thermal curing of the photocrosslinkable pressure-sensitive adhesive layer.

[0156] As a modified example of the method for producing a dicing-die bonding integrated film, the release sheet in step (iv-1) may be replaced with the die bonding tape in step (v), and the formation of the photocrosslinkable pressure-sensitive adhesive layer and the lamination of the dicing tape and die bonding tape may be carried out simultaneously. In this case, the pressure-sensitive adhesive composition is applied onto the adhesive layer of the die bonding tape, thermally cured, and a substrate is laminated on the adhesive layer either before or after thermal curing, thereby obtaining a dicing-die bonding integrated film.

[0157] [Method for producing a cured product (photothermally cured product) of a photocrosslinkable adhesive] <Process (vi)> A cured product (also called a photothermally cured product) of the photocrosslinkable pressure-sensitive adhesive can be produced, for example, by a method including a step (vi) of irradiating the photocrosslinkable pressure-sensitive adhesive with UV light to form a crosslinked structure.

[0158] Examples of light sources used for UV irradiation include high-pressure mercury lamps, ultra-high-pressure mercury lamps, carbon arc lamps, xenon lamps, metal halide lamps, chemical lamps, and black lights.

[0159] The UV irradiation dose for the photocrosslinkable adhesive is 50 to 3,000 mJ / cm 2 is preferably 100 to 600 mJ / cm 2 It is more preferable that the UV irradiation dose applied to the photocrosslinkable adhesive is 50 mJ / cm. 2If the UV irradiation is more than this, the crosslink density of the photocrosslinkable pressure-sensitive adhesive can be improved at a sufficiently fast curing rate. Therefore, when the photocrosslinkable pressure-sensitive adhesive is used in a pressure-sensitive adhesive layer, the adhesive strength of the pressure-sensitive adhesive layer after UV irradiation can be sufficiently reduced. When the photocrosslinkable pressure-sensitive adhesive is used in a resist, the strength can be improved. The UV irradiation dose irradiated to the photocrosslinkable pressure-sensitive adhesive is 3,000 mJ / cm. 2 Even if the UV irradiation dose is increased to more than 3,000 mJ / cm, no further improvement in crosslink density can be obtained. 2 By doing so, it is possible to economically produce a cured product while reducing the effects of UV irradiation on the adherend, and therefore, when the photocrosslinkable pressure-sensitive adhesive is used in a pressure-sensitive adhesive sheet, it can be economically peeled off. [Example]

[0160] The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0161] The raw materials used in the synthesis of the (meth)acrylic resins (A) and (cA) are shown below. In Table 1, the compound names of the raw material monomers are listed with their SP values ((J / cm 3 ) 1 / 2 ) should also be written. Raw material monomer: 2-Hydroxyethyl acrylate, Osaka Organic Chemical Industry Ltd., Styrene, Asahi Kasei Corporation, Isostearyl acrylate, Osaka Organic Chemical Industry Co., Ltd. n-Butyl acrylate, Osaka Organic Chemical Industry Ltd., Cyclohexyl acrylate, Osaka Organic Chemical Industry Ltd. Methyl acrylate, Nippon Shokubai Co., Ltd., Methyl methacrylate, Nippon Shokubai Co., Ltd. Isopropenyl methacrylate, Kuraray Co., Ltd. Radical polymerization initiator: 2,2'-Azobis(N-butyl-2-methylpropionamide), Fujifilm Wako Pure Chemical Industries, Ltd. 2,2'-Azobis(isobutyronitrile), Fujifilm Wako Pure Chemical Industries, Ltd. 2,2'-Azobis(2,4-dimethylvaleronitrile), Fujifilm Wako Pure Chemical Industries, Ltd. RAFT Agents: Benzyldodecyl trithiocarbonate, Fujifilm Wako Pure Chemical Industries, Ltd. 4-Cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid, Fujifilm Wako Pure Chemical Industries, Ltd. Trithiocarbonate bis[[4-[[ethyl-(2-acetoxyethyl)amino]carbonyl]phenyl]methyl]ester, Fujifilm Wako Pure Chemical Industries, Ltd. 2-cyano-2-propyldodecyl trithiocarbonate, Fujifilm Wako Pure Chemical Industries, Ltd. Isocyanato group-containing ethylenically unsaturated compound (a): Karenz (trademark) MOI, 2-isocyanatoethyl methacrylate, Resonac Co., Ltd. AOI-VM (trademark), 2-isocyanatoethyl acrylate, Resonac Co., Ltd.

[0162] Synthesis examples of (meth)acrylic resins (A) and (cA) are shown below. The weight average molecular weight (Mw), molecular weight distribution (Mw / Mn), and hydroxyl value of (meth)acrylic resins (A) and (cA) were measured and calculated by the methods described above. The ethylenically unsaturated group equivalent of (meth)acrylic resins (A) and (cA) was calculated from the charged amounts as described above.

[0163] [Synthesis Example 1] (Process i-2) A reactor equipped with a stirrer, temperature controller, reflux condenser, dropping funnel, and thermometer was charged with 25 moles of styrene, 0.118 parts by mass of benzyldodecyl trithiocarbonate per 100 parts by mass of the raw material monomers (mX) and (mY), and the isocyanato-containing ethylenically unsaturated compound (a), 0.0417 parts by mass of 2,2'-azobis(N-butyl-2-methylpropionamide) per 100 parts by mass of the raw material monomers (mX) and (mY), and the isocyanato-containing ethylenically unsaturated compound (a), and butyl acetate as a solvent so that the total concentration of the raw material monomers (mY), RAFT agent, and radical polymerization initiator was 80% by mass. The temperature was raised to 120°C and the reaction was carried out for 14 hours. (Process i-1) Subsequently, 58 moles of n-butyl acrylate, 17 moles of 2-hydroxyethyl acrylate, and 0.0417 parts by mass of 2,2'-azobis(N-butyl-2-methylpropionamide) per 100 parts by mass of the raw material monomers (mX) and (mY), and the isocyanato group-containing ethylenically unsaturated compound (a), as well as butyl acetate as a solvent, were added so that the total concentration of the polymer obtained in step (i-2), the raw material monomers (mX), and the radical polymerization initiator added in step (i-1) was 80% by mass. The temperature was raised to 120°C, and the reaction was carried out for 14 hours. (Step ii) The reaction mixture was then cooled to room temperature and diluted with butyl acetate so that the concentration of the copolymer obtained in step (i-1) was 40% by mass. The temperature of the diluted reaction mixture was then raised to 55°C, and a mixture of 16 moles of 2-isocyanatoethyl acrylate and dibutyltin dilaurate, a urethane catalyst, was added dropwise through a dropping funnel. The amount of dibutyltin dilaurate added was 0.06 parts by mass relative to 100 parts by mass of the copolymer obtained in step (i-1) and the isocyanate group-containing ethylenically unsaturated compound (a). After the dropwise addition was completed, the reaction system was heated to 60°C for 4 This resulted in a liquid having a solids content of 40% by mass containing a (meth)acrylic resin (A1) having a weight average molecular weight of 300,000, a molecular weight distribution of 2.6, an ethylenically unsaturated group equivalent of 905 g / mol, and a hydroxyl value of 5.05 mgKOH / g.

[0164] [Synthesis Examples 2 to 7] (Meth)acrylic resins (A2) to (A7) were obtained in the same manner as in Synthesis Example 1, except that the compositions shown in Table 1 were used. In Synthesis Example 3, step (ii) was not carried out.

[0165] [Comparative Synthesis Example 1] (Process i-1) A reactor equipped with a stirrer, temperature controller, reflux condenser, dropping funnel, and thermometer was charged with 6 moles of n-butyl acrylate, 16 moles of 2-hydroxyethyl acrylate, and 0.260 parts by mass of trithiocarbonate bis[[4-[[ethyl-(2-acetoxyethyl)amino]carbonyl]phenyl]methyl] ester per 100 parts by mass of the raw material monomers (mX) and (mY), and the isocyanato-containing ethylenically unsaturated compound (a). 0.0160 parts by mass of 2,2'-azobis(2,4-dimethylvaleronitrile) per 100 parts by mass of the raw material monomers (mX) and (mY), and the isocyanato-containing ethylenically unsaturated compound (a). Ethyl acetate was used as a solvent, so that the total concentration of the raw material monomers (mX), RAFT agent, and radical polymerization initiator was 50% by mass. The temperature was raised to 60°C, and the reaction was carried out for 7 hours. (Process i-2) Subsequently, 78 moles of n-butyl acrylate, 0.0160 parts by mass of 2,2'-azobis(2,4-dimethylvaleronitrile) per 100 parts by mass of the raw material monomers (mX) and (mY), and the isocyanato group-containing ethylenically unsaturated compound (a), and ethyl acetate as a solvent were added so that the total concentration of the copolymer obtained in step (i-1), the raw material monomers (mY), and the radical polymerization initiator added in step (i-2) was 50% by mass. After heating to 60°C, the reaction was carried out for 14 hours. (Step ii) The reaction mixture was then cooled to room temperature and diluted with ethyl acetate so that the concentration of the copolymer obtained in step (i-2) was 40% by mass. The temperature of the diluted reaction mixture was then raised to 55°C, and a mixture of 13 moles of 2-isocyanatoethyl methacrylate and dibutyltin dilaurate, a urethanization catalyst, was added dropwise through a dropping funnel. The amount of dibutyltin dilaurate added was 0.06 parts by mass relative to 100 parts by mass of the copolymer obtained in step (i-2) and the isocyanate-containing ethylenically unsaturated compound (a). After the dropwise addition was completed, the reaction system was heated to 60°C. The mixture was left in this state for 4 hours to eliminate the isocyanate groups, thereby obtaining a liquid with a solids content of 40% by mass containing an XYX type (meth)acrylic resin (cA1) with a weight average molecular weight of 300,000, a molecular weight distribution of 2.4, an ethylenically unsaturated group equivalent of 1109 g / mol, and a hydroxyl value of 11.46 mgKOH / g.

[0166] [Comparative Synthesis Example 2] An XYX-type (meth)acrylic resin (cA2) was obtained in the same manner as in Comparative Synthesis Example 1, except that the composition shown in Table 1 was used.

[0167] [Comparative Synthesis Example 3] (Process i-1) A reactor equipped with a stirrer, temperature controller, reflux condenser, dropping funnel, and thermometer was charged with 18 mol of styrene, 10 mol of 2-hydroxyethyl acrylate, 0.156 parts by mass of 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid per 100 parts by mass of the raw material monomers (mX) and (mY), and the isocyanato group-containing ethylenically unsaturated compound (a), 0.0405 parts by mass of 2,2'-azobis(2,4-dimethylvaleronitrile) per 100 parts by mass of the raw material monomers (mX) and (mY), and the isocyanato group-containing ethylenically unsaturated compound (a), and butyl acetate as a solvent such that the total concentration of the raw material monomers (mX), RAFT agent, and radical polymerization initiator was 80% by mass. The temperature was raised to 120°C and the reaction was carried out for 14 hours. (Process i-2) Next, 62 moles of n-butyl acrylate, 10 moles of 2-hydroxyethyl acrylate, 0.0405 parts by mass of 2,2'-azobis(2,4-dimethylvaleronitrile) per 100 parts by mass of the raw material monomers (mX) and (mY), and the isocyanato group-containing ethylenically unsaturated compound (a), and butyl acetate as a solvent were added so that the total concentration of the copolymer obtained in step (i-1), the raw material monomers (mY), and the radical polymerization initiator added in step (i-2) was 80% by mass. After heating to 120°C, the reaction was carried out for 14 hours. (Step ii) The reaction mixture was then cooled to room temperature and diluted with butyl acetate so that the concentration of the copolymer obtained in step (i-2) was 40% by mass. The temperature of the diluted reaction mixture was then raised to 55°C, and a mixture of 18 moles of 2-isocyanatoethyl acrylate and dibutyltin dilaurate, a urethane catalyst, was added dropwise through a dropping funnel. The amount of dibutyltin dilaurate added was 0.06 parts by mass relative to 100 parts by mass of the copolymer obtained in step (i-2) and the isocyanate-containing ethylenically unsaturated compound (a). After the dropwise addition was completed, the reaction system was heated to 60°C for 4 This was held for 1 hour to eliminate the isocyanate groups, yielding a liquid with a solids content of 40% by mass containing a (meth)acrylic resin (cA3) with a weight average molecular weight of 250,000, a molecular weight distribution of 2.4, an ethylenically unsaturated group equivalent of 833 g / mol, and a hydroxyl value of 9.41 mgKOH / g.

[0168] (Comparative Synthesis Example 4) (Process i-1) 63 moles of n-butyl acrylate, 17 moles of 2-hydroxyethyl acrylate, 20 moles of isostearyl acrylate, 0.135 parts by mass of benzyldodecyl trithiocarbonate per 100 parts by mass of the raw material monomer group (mX) and the isocyanato group-containing ethylenically unsaturated compound (a), 0.0563 parts by mass of 2,2'-azobis(isobutyronitrile) per 100 parts by mass of the raw material monomer group (mX) and the isocyanato group-containing ethylenically unsaturated compound (a), and butyl acetate as a solvent were charged into a reaction vessel so that the total concentration of the raw material monomer group (mX), RAFT agent, and radical polymerization initiator was 80% by mass. After heating to 120°C, the reaction was carried out for 14 hours. (Step ii) The reaction mixture was then cooled to room temperature and diluted with butyl acetate so that the concentration of the copolymer obtained in step (i-1) was 40% by mass. The temperature of the diluted reaction mixture was then raised to 55°C, and a mixture of 15 moles of 2-isocyanatoethyl acrylate and dibutyltin dilaurate, a urethane catalyst, was added dropwise through a dropping funnel. The amount of dibutyltin dilaurate added was 0.06 parts by mass relative to 100 parts by mass of the copolymer obtained in step (i-1) and the isocyanate group-containing ethylenically unsaturated compound (a). After the dropwise addition was completed, the reaction system was heated to 60°C for 4 This was held for 1 hour to eliminate the isocyanate groups, yielding a liquid with a solids content of 40% by mass containing a (meth)acrylic resin (cA4) with a weight average molecular weight of 280,000, a molecular weight distribution of 2.1, an ethylenically unsaturated group equivalent of 1221 g / mol, and a hydroxyl value of 5.04 mgKOH / g.

[0169] (Comparative Synthesis Example 5) (Process i-1) A reaction vessel was charged with butyl acetate as a solvent, with the total concentration of the raw material monomer group (mX) and radical polymerization initiator being 60% by mass. 63 moles of n-butyl acrylate, 17 moles of 2-hydroxyethyl acrylate, 20 moles of isostearyl acrylate, and 0.297 parts by mass of 2,2'-azobis(isobutyronitrile) per 100 parts by mass of the raw material monomer group (mX) and the isocyanato group-containing ethylenically unsaturated compound (a) were mixed to prepare a mixed solution. After heating the butyl acetate in the reaction vessel to 80°C, the mixed solution was added dropwise over 3 hours. After the addition was completed, the reaction was continued at 80°C for 4 hours. (Step ii) The reaction mixture was then cooled to room temperature and diluted with butyl acetate so that the concentration of the copolymer obtained in step (i-1) was 40% by mass. The temperature of the diluted reaction mixture was then raised to 55°C, and a mixture of 15 moles of 2-isocyanatoethyl acrylate and dibutyltin dilaurate, a urethane catalyst, was added dropwise through a dropping funnel. The amount of dibutyltin dilaurate added was 0.06 parts by mass relative to 100 parts by mass of the copolymer obtained in step (i-1) and the isocyanate group-containing ethylenically unsaturated compound (a). After the dropwise addition was completed, the reaction system was heated to 60°C for 4 This was held for 1 hour to eliminate the isocyanate groups, yielding a liquid with a solids content of 40% by mass containing a (meth)acrylic resin (cA5) with a weight average molecular weight of 320,000, a molecular weight distribution of 4.2, an ethylenically unsaturated group equivalent of 1221 g / mol, and a hydroxyl value of 5.04 mgKOH / g.

[0170] [Table 1-1] [Table 1-2] [Table 1-3] [Table 1-4]

[0171] The raw materials used in the preparation of the pressure-sensitive adhesive composition are shown below. Photoinitiator (B): TPO: 2,4,6-trimethylbenzoyldiphenylphosphine oxide (BASF, trade name: L-TPO) Irgacure 500: A mixture of 1-hydroxycyclohexyl phenyl ketone and benzophenone (BASF, trade name: Irgacure 500) Crosslinker (C) Takenate: Trimethylolpropane tolylene diisocyanate adduct (Mitsui Chemicals, Inc., product name: Takenate D-101E) L-55E: Trimethylolpropane tolylene diisocyanate adduct (Tosoh Corporation, product name: Coronate L-55E) L-45E: Trimethylolpropane tolylene diisocyanate adduct (Tosoh Corporation, product name: Coronate L-45E)

[0172] [Preparation of Pressure-Sensitive Adhesive Composition] Ethyl acetate, a dilution solvent, was added to the liquids containing the (meth)acrylic resins (A1) to (A7) and (cA1) to (cA5) obtained in Synthesis Examples 1 to 7 and Comparative Synthesis Examples 1 to 5 so that the contents of the (meth)acrylic resins (A1) to (A7) and (cA1) to (cA5) were adjusted to 30 mass %. Using these liquids, pressure-sensitive adhesive compositions were obtained by the method described below.

[0173] In a room shielded from actinic radiation, the (meth)acrylic resin (A) or (cA), the photopolymerization initiator (B), and the crosslinking agent (C) shown in Table 2 were added to a plastic container in the amounts (parts by mass) shown in Table 2, respectively, and stirred to obtain pressure-sensitive adhesive compositions (B1) to (B7) and (cB1) to (cB5).

[0174] [Example 1] Preparation of adhesive sheet A silicone-based, light-release PET film (Toyobo Co., Ltd., product name: E7006, thickness: 25 μm) was prepared as a release sheet, and the pressure-sensitive adhesive composition (B1) was applied to the release-treated surface using an applicator so that the thickness after thermal curing would be 11 μm. The film was then dried by heating at 110°C for 2 minutes to form a pressure-sensitive adhesive composition layer. Next, a 90 μm-thick PO film was prepared as a sheet-like substrate. The PO film was attached to the pressure-sensitive adhesive composition layer using a rubber roller so that the corona-treated surface of the PO film was adhered to the exposed surface of the pressure-sensitive adhesive composition layer. The film was then cured in an oven at 40°C for 3 days, and the pressure-sensitive adhesive composition layer was crosslinked and cured to obtain the pressure-sensitive adhesive sheet of Example 1.

[0175] [Examples 2 to 7 and Comparative Examples 1 to 5] Preparation of adhesive sheets The pressure-sensitive adhesive sheets of Examples 2 to 7 and Comparative Examples 1 to 5 were obtained in the same manner as in Example 1, except that pressure-sensitive adhesive compositions (B2) to (B7) and (cB1) to (cB5) were used instead of pressure-sensitive adhesive composition (B1), and the thickness of the pressure-sensitive adhesive composition layer after thermal curing was as shown in Table 2.

[0176] [Adhesion evaluation] (1) Measurement of initial adhesive strength (180° peel strength) The adhesive strength of the pressure-sensitive adhesive sheets according to the Examples and Comparative Examples to a wafer was evaluated by measuring the 180° peel strength as follows. Samples measuring 25 mm wide and 100 mm long were cut out from the pressure-sensitive adhesive sheets of Examples 1 to 7 and Comparative Examples 1 to 5. The silicone-based light-release PET film was peeled off to expose the adhesive layer, which was then attached to a test dummy wafer (AS ONE Corporation) with a rubber roller. The wafer was pressed using an autoclave (TAC-200, Sakura Seiki Co., Ltd.) to obtain a sample for adhesive strength measurement. The peel strength of the pressure-sensitive adhesive sheet to the wafer was measured using a tensile tester (TAXT2i, Stable Micro Systems) and determined as the initial adhesive strength. The measurement conditions were a peel angle of 180° and a pulling speed of 5 mm / sec. The samples were stored and the peel strength was measured at a temperature of 23°C and a relative humidity of 4°C. The results are shown in Table 2.

[0177] (2) Measurement of adhesive strength after immersion (180° peel strength) (1) A sample for measuring adhesive strength was prepared using the same method as for measuring initial adhesive strength (180° peel strength). The obtained sample was immersed in ion-exchange water and left to stand in a dark place for 3 hours at a temperature of 23°C and a relative humidity of 40%. After the immersion treatment, the sample was removed and excess water was removed. The peel strength of the adhesive sheet against the wafer was measured using the same method as for measuring initial adhesive strength (180° peel strength), and this was determined as the adhesive strength after immersion. The rate of change in adhesive strength was calculated from the measurement results using the following formula. The results are shown in Table 2. Adhesive strength change rate (%) = ((adhesive strength after immersion) - (initial adhesive strength) / (initial adhesive strength)) x 100

[0178] (3) Measurement of adhesive strength (30° peel strength) after UV irradiation (1) A sample for measuring adhesive strength was prepared using the same method as for measuring the initial adhesive strength (180° peel strength). The obtained sample was irradiated with 300 mJ / cm from the substrate side of the adhesive sheet. 2 The adhesive sheet was irradiated with ultraviolet (UV) light under the conditions shown above to obtain a sample for measuring adhesive strength after UV irradiation. A conveyor-type UV irradiation device (Eye Graphics Co., Ltd., 2 kW lamp, 80 W / cm) was used for UV irradiation. The peel strength of the adhesive sheet against the wafer was then measured in the same manner as in (1) Measurement of Initial Adhesion Strength (180° Peel Strength), except that the peel angle was changed to 30°, and this was determined as the adhesive strength after UV irradiation. The results are shown in Table 2.

[0179] [Table 2-1] [Table 2-2]

[0180] [Production of integrated dicing and die bonding film] The adhesive layer was exposed by peeling off one cover film from a die bonding film (FH-D25T-50, Resonac Corporation), in which both sides of the adhesive layer were protected by a cover film. This adhesive layer was then bonded with the adhesive layer of each of the pressure-sensitive adhesive sheets of Examples 1 to 7 and Comparative Examples 1 to 5, in which the adhesive layer had been exposed by peeling off the light-release PET film, using a rubber roller. The resulting film was left at room temperature for one day, yielding an integrated dicing and die bonding film.

[0181] [Processability evaluation] (1) Blade dicing test (dicing ability) A semiconductor wafer was diced using a dicing and die bonding integrated film in the following manner. After dicing, the number of chips that had blown off among the semiconductor chips (total number: 400), i.e., the number of semiconductor chips that had detached from the dicing and die bonding integrated film and scattered, was counted, and the chip blowout rate (%) was calculated to evaluate the dicing properties. Therefore, the closer the chip blowout rate is to 0%, the better the dicing properties are.

[0182] First, the backside of a semiconductor wafer (8-inch diameter, 0.6 mm thick; silicon mirror wafer) was polished to obtain a 0.2 mm thick mirror wafer. Next, the cover film was peeled off from the integrated dicing and die bonding film, exposing the adhesive layer, and the mirror wafer was then bonded to it by roll compression at 70°C. The mirror wafer was then diced. The mirror wafer was then fully cut to produce chips measuring 1.0 mm square. The bonding and dicing conditions were as follows:

[0183] <Semiconductor wafer polishing conditions> Grinding device: Product name DFG-8560 (Disco Corporation) Semiconductor wafer: 8-inch diameter (back-polished from 0.6mm to 0.2mm thick)

[0184] <Bonding conditions> Adhesive device: Product name MA-3000III (Nitto Seiki Co., Ltd.) Pasting speed: 10mm / min Pasting pressure: 0.15MPa Stage temperature during application: 70℃

[0185] <Dicing conditions> Dicing machine: Product name DFD-6361 (Disco Corporation) Dicing ring: 2-8-1 (Disco Corporation) Dicing speed: 30mm / sec Dicing blade: Z1; 203O-SE 27HCDD (Disco Corporation) Z2;203O-SE 27HCBB (DISCO Corporation) Dicing blade rotation speed: Z1; 40,000 r / min Z2: 45,000 r / min Cutting method: Step cut Wafer chip size: 1.0mm square Cutting water supply amount: 2.0L / min

[0186] <Evaluation criteria for dicing performance> S: The chipping rate was 0% or more and less than 5%. A: The chipping rate was 5% or more and less than 10%. B: The chipping rate was 10% or more and less than 20%. C: The chipping rate was 20% or more.

[0187] (2) Pickup test (pickup ability) After dicing the mirror wafer as described above, the semiconductor chips were picked up. Pickup was performed after irradiating the adhesive layer with ultraviolet light. The irradiation conditions were as follows: After ultraviolet light irradiation, the semiconductor chips with adhesive pieces obtained by dicing were pushed up with a needle from the dicing tape side of the integrated dicing and die bonding film and picked up from the adhesive layer. At this time, the success rate (%) of picking up the semiconductor chips (total number: 400) was calculated and the pick-up ability was evaluated. Therefore, the closer the pick-up rate is to 100%, the better the pick-up ability. Note that chips with loose chips were not included in the parameter. The pick-up conditions are as follows:

[0188] <Ultraviolet light irradiation conditions> Ultraviolet (UV) irradiation equipment: high-pressure mercury lamp UV irradiation cumulative light intensity: 500mJ / cm 2 Output: 75W Irradiation intensity: 150mW / cm 2 The ultraviolet light was irradiated from the surface of the dicing tape facing the substrate.

[0189] <Pickup conditions> Pickup device: Product name SPA-300 (Shinkawa Co., Ltd.) Number of pickup needles: 1 Needle thrust speed: 20 mm / sec Needle thrust amount: 500 μm Pickup time: 1 second Dicing tape expansion amount: 3 mm <Evaluation criteria> S: The success rate of the pickup was 95% or more (100%). A: The pickup success rate was between 80% and 95%. B: The pickup success rate was between 60% and 80%. C: Pickup success rate was less than 60%.

[0190] The pressure-sensitive adhesive sheets according to Examples 1 to 7 had a small rate of change in adhesive strength and excellent water resistance. The integrated dicing and die bonding films produced using the pressure-sensitive adhesive sheets according to Examples 1 to 7 showed good results in both the blade dicing test and the pick-up test. [Industrial Applicability]

[0191] According to the present disclosure, there is provided a pressure-sensitive adhesive composition that provides a pressure-sensitive adhesive sheet having high adhesive strength and excellent water resistance against cutting water, and whose adhesive strength is significantly reduced by irradiation with ultraviolet light. A pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition can be preferably used as a pressure-sensitive adhesive layer for a removable pressure-sensitive adhesive sheet, particularly a dicing tape.

Claims

1. a (meth)acrylic resin (A); a photopolymerization initiator (B); a crosslinking agent (C); Contains the (meth)acrylic resin (A) is a diblock copolymer consisting of an X block and a Y block, the structural unit ratio (molar ratio) of the X block to the Y block is 40:60 to 85:15; The X block is A structural unit (M-1) having a hydroxy group, and Structural unit (M-2) having an ethylenically unsaturated group and The Y block is SP value is 20 (J / cm ３ ) １／２ A structural unit (M-3) derived from the following ethylenically unsaturated compound (m-3), which does not have an ethylenically unsaturated group or a hydroxy group, and Optionally, one or more structural units selected from the group consisting of a structural unit (M-1) having a hydroxy group and a structural unit (M-2) having an ethylenically unsaturated group. and at least one of the structural unit (M-1), the structural unit (M-2), and the structural unit (M-3) has a structure derived from a (meth)acryloyloxy group; the total proportion of the structural unit (M-1) having a hydroxy group and the structural unit (M-2) having an ethylenically unsaturated group in the X block is 18 to 95 mol %, relative to 100 mol % of the total structural units in the X block; the total proportion of the structural unit (M-1) having a hydroxy group and the structural unit (M-2) having an ethylenically unsaturated group in the Y block is 0 to 17 mol %, relative to 100 mol % of the total structural units in the Y block; the proportion of the structural unit (M-1) having a hydroxy group in the X block is 1.5 mol % or more, relative to 100 mol % of the total structural units in the X block; the proportion of the structural unit (M-2) having an ethylenically unsaturated group in the X block is 15 mol % or more, relative to 100 mol % of the total structural units in the X block; The pressure-sensitive adhesive composition, wherein the proportion of structural units (M-3) derived from an ethylenically unsaturated compound (m-3) having an SP value of 20 (J / cm 3 ) 1 / 2 or less in the Y block is 80 mol % or more, relative to 100 mol % of the total structural units in the Y block.

2. The pressure-sensitive adhesive composition according to claim 1, wherein the proportion of the structural unit (M-2) having an ethylenically unsaturated group in the X block is 15 to 60 mol %, relative to 100 mol % of the total structural units in the X block.

3. 2. The pressure-sensitive adhesive composition according to claim 1, wherein the proportion of the structural unit (M-1) having a hydroxy group in the X block is 1.5 to 35 mol %, relative to 100 mol % of the total structural units in the X block.

4. The pressure-sensitive adhesive composition according to claim 1, wherein the structural unit (M-2) having an ethylenically unsaturated group in the X block is a structural unit in which an isocyanato group-containing ethylenically unsaturated compound (a) is added to a hydroxy group of a structural unit derived from an ethylenically unsaturated compound (m-1) having a hydroxy group.

5. The SP value of the Y block is 20 (J / cm ３ ) １／２ The pressure-sensitive adhesive composition according to claim 1, wherein the structural unit (M-3) derived from the following ethylenically unsaturated compound (m-3) is a structural unit derived from a monomer selected from the group consisting of linear or branched alkyl(meth)acrylates having an alkyl group with 6 to 30 carbon atoms, alicyclic skeleton-containing (meth)acrylates, and styrene.

6. The pressure-sensitive adhesive composition according to claim 1 , wherein the Y block has a structural unit derived from styrene.

7. 2. The pressure-sensitive adhesive composition according to claim 1, wherein the X block further comprises a structural unit derived from a linear or branched alkyl (meth)acrylate in which the alkyl group has 1 to 5 carbon atoms.

8. The weight average molecular weight of the (meth)acrylic resin (A) is 1×10 ４ ~200 x 10 ４ The pressure-sensitive adhesive composition according to claim 1,

9. The pressure-sensitive adhesive composition according to claim 1, wherein the (meth)acrylic resin (A) has an ethylenically unsaturated group equivalent of 100 to 5000 g / mol.

10. The pressure-sensitive adhesive composition according to claim 1, wherein the (meth)acrylic resin (A) has a hydroxyl value of 0.01 to 50 mgKOH / g.

11. a substrate layer; A pressure-sensitive adhesive layer comprising a heat-cured or photo-cured product of the pressure-sensitive adhesive composition according to any one of claims 1 to 10; An adhesive sheet having the above structure.

12. a substrate layer; A pressure-sensitive adhesive layer comprising a heat-cured or photo-cured product of the pressure-sensitive adhesive composition according to any one of claims 1 to 10; A dicing tape having

13. a substrate layer; A pressure-sensitive adhesive layer comprising a heat-cured or photo-cured product of the pressure-sensitive adhesive composition according to any one of claims 1 to 10; an adhesive layer; A dicing and die bonding integrated film having the above in this order.

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