WO2021019868A1 - 粘着シートおよび粘着剤組成物 - Google Patents
粘着シートおよび粘着剤組成物 Download PDFInfo
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- WO2021019868A1 WO2021019868A1 PCT/JP2020/019734 JP2020019734W WO2021019868A1 WO 2021019868 A1 WO2021019868 A1 WO 2021019868A1 JP 2020019734 W JP2020019734 W JP 2020019734W WO 2021019868 A1 WO2021019868 A1 WO 2021019868A1
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- Prior art keywords
- pressure
- sensitive adhesive
- meth
- polyurethane
- adhesive composition
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Classifications
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J7/00—Adhesives in the form of films or foils
- C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
- C09J7/38—Pressure-sensitive adhesives [PSA]
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
- C09J11/02—Non-macromolecular additives
- C09J11/06—Non-macromolecular additives organic
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J175/00—Adhesives based on polyureas or polyurethanes; Adhesives based on derivatives of such polymers
- C09J175/04—Polyurethanes
- C09J175/08—Polyurethanes from polyethers
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J175/00—Adhesives based on polyureas or polyurethanes; Adhesives based on derivatives of such polymers
- C09J175/04—Polyurethanes
- C09J175/14—Polyurethanes having carbon-to-carbon unsaturated bonds
- C09J175/16—Polyurethanes having carbon-to-carbon unsaturated bonds having terminal carbon-to-carbon unsaturated bonds
Definitions
- the present invention relates to pressure-sensitive adhesive sheets and pressure-sensitive adhesive compositions.
- the present application claims priority based on Japanese Patent Application No. 2019-138812 filed in Japan on July 29, 2019, the contents of which are incorporated herein by reference.
- the back grind process of semiconductor wafers is being performed in the manufacturing process of semiconductor devices.
- the front surface of the semiconductor wafer is protected by an adhesive sheet, and then the back surface is ground to make the semiconductor wafer thinner.
- a back grind sheet having an unevenness absorbing layer on a substrate wherein the unevenness absorbing layer is a polymerization other than (A) urethane (meth) acrylate and (B) (A) component.
- a backgrinding sheet is disclosed, which is a layer formed from a film-forming composition containing a sex monomer and satisfying a specific range of loss tangent, relaxation rate, and storage elastic modulus.
- the adhesive sheet used to protect the surface is required to have sufficient adhesive strength.
- the adhesive of the adhesive sheet is applied around the bumps of the semiconductor wafer from which the adhesive sheet has been peeled off after the back grind process. Adhesive residue to which the layer is transferred is generated.
- the adhesive sheet used for the purpose of being attached to an adherend having an uneven portion on the surface and then peeled off has sufficient adhesive strength, is less likely to cause adhesive residue, and has uneven absorption. Is required to be excellent.
- the conventional adhesive sheet has sufficient adhesive strength, is less likely to cause adhesive residue, and is not excellent in unevenness absorption. Therefore, when a conventional pressure-sensitive adhesive sheet is used, in order to obtain sufficient adhesive strength and unevenness-absorbing property on the semiconductor wafer, an unevenness-absorbing layer is provided separately from the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet, or the pressure-sensitive adhesive layer is heated. It had to be softened.
- the present invention has been made in view of the above circumstances, has sufficient adhesive strength, is less likely to leave adhesive residue on which the adhesive layer is transferred to the adherend after the adhesive sheet is peeled off, and is uneven.
- An object of the present invention is to provide an adhesive sheet having excellent absorbency.
- the present invention provides a pressure-sensitive adhesive composition which has sufficient adhesive strength, hardly causes adhesive residue, and has excellent unevenness absorption, and is suitable as a material for the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet. The purpose is to do.
- the first aspect of the present invention is the following adhesive sheet.
- a pressure-sensitive adhesive sheet having at least a sheet-like base material and a pressure-sensitive adhesive layer formed on one side of the base material.
- the pressure-sensitive adhesive layer is made of a cured product of the pressure-sensitive adhesive composition, and has a gel fraction of 50 to 65% by mass.
- the pressure-sensitive adhesive composition comprises a polyurethane (A), a (meth) acrylic monomer (B) composed of a compound having a (meth) acryloyloxy group, a chain transfer agent (C), and a photopolymerization initiator (D).
- the polyurethane (A) is characterized by containing a polyurethane (a1) having a skeleton containing a structure derived from a polyoxyalkylene polyol and a structure derived from a polyisocyanate, and having a (meth) acryloyl group at two or more ends. Adhesive sheet to do.
- the pressure-sensitive adhesive sheet according to the first aspect of the present invention preferably includes the following features [2] to [3]. The following features may be combined with each other.
- the pressure-sensitive adhesive layer has a storage elastic modulus at 25 ° C. was measured at a frequency 1Hz is 1.0 ⁇ 10 4 ⁇ 1.0 ⁇ 10 5, The adhesive sheet according to [1], wherein the loss tangent at 25 ° C. measured at a frequency of 1 Hz is 0.25 to 0.55.
- the second aspect of the present invention is the following pressure-sensitive adhesive composition.
- [4] Containing a polyurethane (A), a (meth) acrylic monomer (B) composed of a compound having a (meth) acryloyloxy group, a chain transfer agent (C), and a photopolymerization initiator (D).
- the polyurethane (A) contains a polyurethane (a1) having a skeleton containing a structure derived from a polyoxyalkylene polyol and a structure derived from a polyisocyanate, and having a (meth) acryloyl group at two or more ends.
- a pressure-sensitive adhesive composition, wherein the gel content of the cured product photo-cured at an irradiation amount of 1000 mJ / cm 2 is 50 to 65% by mass.
- the pressure-sensitive adhesive composition of the second aspect of the present invention preferably contains the following features [5] to [10]. The following features may be combined with each other.
- [5] The cured product has a storage elastic modulus at 25 ° C. was measured at a frequency 1Hz is 1.0 ⁇ 10 4 ⁇ 1.0 ⁇ 10 5,
- the pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer composed of a cured product of a specific pressure-sensitive adhesive composition and having a gel fraction of 50 to 65% by mass on one side of a sheet-like base material. Therefore, the pressure-sensitive adhesive sheet of the present invention has sufficient adhesive strength, is less likely to leave adhesive residue on which the pressure-sensitive adhesive layer is transferred to the adherend after the pressure-sensitive adhesive sheet is peeled off, and is excellent in unevenness absorption. Therefore, when the adhesive sheet of the present invention is attached to an adherend having an uneven portion on the surface and then peeled off, the adhesive layer has irregularities separately from the adhesive layer as in the case of using a conventional adhesive sheet. There is no need to provide an absorbent layer or heat the pressure-sensitive adhesive layer to soften it. Therefore, the pressure-sensitive adhesive sheet of the present invention is suitable for applications where it is attached to an adherend having an uneven portion on its surface and then peeled off.
- the pressure-sensitive adhesive composition of the present invention has a specific composition and gel fraction. Therefore, by curing the pressure-sensitive adhesive composition of the present invention, a cured product having sufficient adhesive strength, less likely to leave adhesive residue, and excellent in unevenness absorption can be obtained. Therefore, the pressure-sensitive adhesive composition of the present invention is suitable as a material for a pressure-sensitive adhesive layer in a pressure-sensitive adhesive sheet that is attached to an adherend having an uneven portion on the surface and then peeled off.
- the pressure-sensitive adhesive sheet and the pressure-sensitive adhesive composition of the present invention will be described in detail.
- the present invention is not limited to the embodiments shown below. Within the scope of the present invention, it is possible to omit, change, replace, and / or add the type, amount, composition, ratio, number, numerical value, position, size, and the like, if necessary.
- ⁇ Adhesive sheet> The pressure-sensitive adhesive sheet of the present embodiment has a sheet-like base material and a pressure-sensitive adhesive layer formed on one side of the base material.
- the pressure-sensitive adhesive layer is composed of a cured product of the pressure-sensitive adhesive composition described later.
- the material of the base material can be appropriately selected, and examples thereof include a resin material.
- a resin material polyolefins such as polyethylene (PE) and polypropylene (PP); polyester sheets such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT) and polyethylene naphthalate; polyvinyl chloride (PVC); polyimide (PI). ; Polyphenylene terephide (PPS); ethylene vinyl acetate (EVA); polytetrafluoroethylene (PTFE) and the like.
- PE, PP, and PET are preferably used because a sheet having appropriate flexibility can be obtained. Only one type of resin material may be used alone, or two or more types may be mixed and used.
- the resin sheet When a resin sheet made of a resin material is used as the base material, the resin sheet may have a single layer or a multi-layer structure having two or more layers (for example, a three-layer structure).
- the resin material constituting each layer may be a resin material containing only one kind alone or a resin material containing two or more kinds.
- a base material that has been subjected to antistatic treatment may be used as the base material.
- the antistatic treatment applied to the base material is not particularly limited, but a method of providing an antistatic layer on at least one surface of the base material, a method of kneading an antistatic agent into the base material, and the like can be used. Further, the surface on which the pressure-sensitive adhesive layer of the base material is formed is subjected to easy-adhesion treatment such as acid treatment, alkali treatment, primer treatment, corona treatment, plasma treatment, ultraviolet treatment, ozone treatment, etc., if necessary. You may.
- the thickness of the base material can be appropriately selected according to the material of the base material and the like.
- the adhesive sheet is used for protecting a semiconductor wafer having uneven portions on the surface in the processing process of the semiconductor wafer, and when a resin sheet is used as the base material, the thickness of the base material is, for example, 10 to 1000 ⁇ m. It is preferably 50 to 300 ⁇ m.
- the thickness of the base material is 10 ⁇ m or more, the rigidity (stiffness) of the adhesive sheet becomes high. Therefore, when the adhesive sheet is attached to or peeled off from the semiconductor wafer as an adherend, the adhesive sheet tends to be less likely to wrinkle or float.
- the thickness of the base material is 1000 ⁇ m or less, the pressure-sensitive adhesive sheet attached to the semiconductor wafer can be easily peeled off from the semiconductor wafer, and workability (handleability, handling) is improved.
- the thickness of the pressure-sensitive adhesive layer is preferably 50 to 500 ⁇ m, more preferably 60 to 400 ⁇ m, and even more preferably 70 to 300 ⁇ m.
- the thickness of the pressure-sensitive adhesive layer is 50 ⁇ m or more, the unevenness absorption of the pressure-sensitive adhesive sheet becomes even better. Further, when the thickness of the pressure-sensitive adhesive layer is 500 ⁇ m or less, the film thickness of the pressure-sensitive adhesive layer can be easily controlled.
- the thickness of the adhesive layer largely depends on the height of the uneven portion on the surface.
- the thickness of the pressure-sensitive adhesive layer is preferably equal to or greater than the height of the uneven portion on the surface so that sufficient uneven absorption can be obtained. Therefore, for example, when the unevenness of the surface is a bump formed on the semiconductor wafer, it is preferable that the thickness of the pressure-sensitive adhesive layer is twice or more the height dimension of the bump.
- the height of the bump is usually 30 to 200 ⁇ m. For example, when the height of the bump is 100 ⁇ m, the thickness of the adhesive layer is preferably 200 ⁇ m or more, and when the height of the bump is 200 ⁇ m.
- the thickness of the pressure-sensitive adhesive layer is preferably 400 ⁇ m or more.
- the pressure-sensitive adhesive layer contained in the pressure-sensitive adhesive sheet of the present embodiment has a gel fraction in the range of 50 to 65% by mass. Therefore, the pressure-sensitive adhesive sheet of the present embodiment has sufficient adhesive strength, is less likely to cause adhesive residue, and is excellent in unevenness absorption.
- the gel fraction of the pressure-sensitive adhesive layer is preferably 52% by mass or more.
- the gel fraction of the pressure-sensitive adhesive layer is preferably 63% by mass or less.
- the gel fraction is less than 50% by mass, the adhesive sheet is attached to the adherend and then peeled off, so that adhesive residue is likely to occur.
- the gel fraction exceeds 65% by mass, the fluidity when used as the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet tends to be insufficient. Therefore, when the adhesive sheet is sent to an adherend having an uneven portion on the surface, a gap is likely to be generated between the adhesive sheet and the uneven portion of the adherend.
- the gel fraction of the pressure-sensitive adhesive layer can be measured, for example, by the method shown below. A square sheet having a length of 8 cm and a width of 8 cm is cut out from the adhesive sheet, and the base material is peeled off from the adhesive layer of the obtained square sheet. Then, the pressure-sensitive adhesive layer peeled off from the square sheet is used as a measurement sample.
- the obtained measurement sample can be measured by using the same method as the method for measuring the gel fraction of the measurement sample composed of the cured product of the pressure-sensitive adhesive composition described later.
- Pressure-sensitive adhesive layer having a pressure-sensitive adhesive sheet of the present embodiment is 1.0 a ⁇ 10 4 ⁇ 1.0 ⁇ 10 5 is the storage elastic modulus at 25 ° C. was measured at a frequency 1Hz, and, 25 ° C. was measured at a frequency 1Hz
- the loss tangent is preferably 0.25 to 0.55.
- the pressure-sensitive adhesive layer having a storage modulus and loss tangent in the above range has good flexibility and fluidity. Therefore, when the pressure-sensitive adhesive sheet is attached to a work (adhesive body) such as a semiconductor wafer having uneven parts such as bumps, it is possible to prevent the generation of voids between the uneven parts and the pressure-sensitive adhesive sheet.
- Storage modulus of the pressure-sensitive adhesive layer is more preferably 2.0 ⁇ 10 4 or more, more preferably 3.0 ⁇ 10 4 or more. Further, the storage elastic modulus is more preferably 9.0 ⁇ 10 4 or less, further preferably 8.0 ⁇ 10 4 or less. Pressure-sensitive adhesive layer above storage elastic modulus is 1.0 ⁇ 10 4 or more, is not too soft. Therefore, PSA sheet storage modulus has a pressure-sensitive adhesive layer is 1.0 ⁇ 10 4 or more, be peeled off after attached to an adherend, even more adhesive residue is less likely to occur, preferably. Further, the pressure-sensitive adhesive layer above storage elastic modulus is 1.0 ⁇ 10 5 or less, has a good flexibility.
- the loss tangent of the pressure-sensitive adhesive layer is more preferably 0.30 or more. Further, the loss tangent is more preferably 0.50 or less.
- the pressure-sensitive adhesive layer having a loss tangent of 0.25 or more has good fluidity. Therefore, when an adhesive sheet having an adhesive layer having a loss tangent of 0.25 or more is attached to an adherend having an uneven portion on the surface, a gap is generated between the adhesive sheet and the uneven portion of the adherend. Difficult and preferable. Further, the pressure-sensitive adhesive layer having the loss tangent of 0.55 or less does not have too large fluidity. Therefore, an adhesive sheet having an adhesive layer having a loss tangent of 0.55 or less is preferable because adhesive residue is unlikely to occur even if the adhesive sheet is peeled off after being attached to the adherend.
- the storage elastic modulus and loss tangent of the pressure-sensitive adhesive layer can be measured by, for example, the methods shown below. First, the base material is peeled off from the adhesive sheet. Then, the pressure-sensitive adhesive layer from which the base material has been peeled off is laminated to obtain a laminated sheet having a thickness within the range of 1 to 2 mm. A square sheet having a length of 8 mm and a width of 8 mm is cut out from the obtained laminated sheet and used as a measurement sample. The obtained measurement sample can be measured by using the same method as the method for measuring the storage elastic modulus and the loss tangent of the measurement sample composed of the cured product of the pressure-sensitive adhesive composition described later.
- the pressure-sensitive adhesive sheet may be provided with a transparent separator on the surface of the pressure-sensitive adhesive layer opposite to the base material for the purpose of protecting the pressure-sensitive adhesive layer.
- the separator is preferably laminated on the surface of the pressure-sensitive adhesive layer.
- the material of the separator for example, paper, a plastic film, or the like can be used, and it is preferable to use a plastic film from the viewpoint of excellent surface smoothness.
- the plastic film used as the separator is not particularly limited as long as it can protect the above-mentioned pressure-sensitive adhesive layer, and examples thereof include polyethylene, polypropylene, polyethylene terephthalate, and polybutene.
- the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of the present embodiment is made of a cured product of the pressure-sensitive adhesive composition.
- the pressure-sensitive adhesive composition used as the material of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of the present embodiment will be described in detail.
- the pressure-sensitive adhesive composition of the present embodiment contains a polyurethane (A), a (meth) acrylic monomer (B), a chain transfer agent (C), and a photopolymerization initiator (D).
- Polyurethane (A) Polyurethane (A) contains polyurethane (a1).
- the polyurethane (A) may contain not only the polyurethane (a1) but also the polyurethane (a2) described later for the purpose of adjusting the cohesive force of the cured product of the pressure-sensitive adhesive composition. It is preferable that the polyurethane (A) does not contain components other than the polyurethane (a1) and the polyurethane (a2) contained if necessary.
- Polyurethane (a1) has a skeleton containing a structure derived from a polyoxyalkylene polyol and a structure derived from a polyisocyanate.
- polyurethane (a1) has two or more, that is, (meth) acryloyl groups at a plurality of ends.
- the terminal (meth) acryloyl group of the polyurethane (a1) is preferably a part of the (meth) acryloyloxy group.
- the "plurality of ends" of polyurethane means two ends when the polyurethane is a linear polymer, and two of the same number of ends as the number of each branched chain when the polyurethane is a branched polymer. One or more ends.
- Polyurethane (a2) Polyurethane (a2), like polyurethane (a1), has a skeleton containing a structure derived from a polyoxyalkylene polyol and a structure derived from a polyisocyanate. Polyurethane (a2), unlike polyurethane (a1), has a (meth) acryloyl group at only one end. The terminal (meth) acryloyl group of the polyurethane (a2) is preferably a part of the (meth) acryloyloxy group.
- the terminal of the polyurethane (a2) having no (meth) acryloyl group preferably has any one selected from an isocyanato group, a structure derived from an alkyl alcohol, and a structure derived from an alkyl isocyanate, and has a structure derived from an alkyl alcohol. Is more preferable.
- the polyoxyalkylene polyol having a structure derived from the polyoxyalkylene polyol contained in the skeletons of the polyurethane (a1) and the polyurethane (a2) preferably has an alkylene chain having 2 to 4 carbon atoms. Specific examples include polyoxyethylene polyol, polyoxypropylene polyol, and polyoxybutylene polyol.
- the polyoxyalkylene polyol having a structure derived from the polyoxyalkylene polyol may contain one kind of alkylene chain or may contain two or more kinds of alkylene chains.
- the polyoxyalkylene polyol having a structure derived from the polyoxyalkylene polyol is preferably one having two or three hydroxyl groups at the terminal (diol type or triol type polyoxyalkylene polyol), and is preferably a polyoxyalkylene glycol (diol). Type) is more preferable, and polypropylene glycol having an alkylene chain having 3 carbon atoms is particularly preferable.
- the hydroxyl value is preferably 20 to 120 mgKOH / g, more preferably 30 to 100 mgKOH / g, and further preferably 40 to 80 mgKOH / g. preferable.
- polypropylene glycol include polypropylene glycol (Actcol D-2000; manufactured by Mitsui Chemicals, number average molecular weight 2000, diol type) having a hydroxyl group (hydroxy group) having a hydroxyl value of 56 mgKOH / g at the end. Be done.
- the hydroxyl value of the polyoxyalkylene polyol is the hydroxyl value of the polyoxyalkylene polyol measured according to JIS K0070. That is, it means the number of mg of potassium hydroxide required to neutralize free acetic acid when 1 g of polyoxyalkylene polyol is acetylated. Specifically, it can be obtained by acetylating the hydroxyl groups in the sample (polyoxyalkylene polyol) with acetic anhydride and titrating the free acetic acid generated at that time with a potassium hydroxide solution.
- the number average molecular weight of the polyoxyalkylene polyol is preferably 500 to 5,000, more preferably 800 to 4,000, and even more preferably 1,000 to 3,000.
- the pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer made of a cured product of the pressure-sensitive adhesive composition containing polyurethane (A) synthesized using the polyoxyalkylene polyol has high peel strength. It becomes.
- the number average molecular weight of the polyoxyalkylene polyol is 5,000 or less, the polyurethane (A) synthesized by using the polyoxyalkylene polyol contains a sufficient amount of urethane bonds. Therefore, the cured product obtained by curing the pressure-sensitive adhesive composition containing polyurethane (A) has a good cohesive force.
- the structure derived from the polyoxyalkylene polyol contained in the skeletons of the polyurethane (a1) and the polyurethane (a2) may be of only one type, or may be a structure containing two or more types.
- Polyurethane (a1) and polyurethane (a2) may have a structure in which two or more different polyoxyalkylene polyol-derived structures are bonded with a polyisocyanate-derived structure in between.
- the structure derived from the polyoxyalkylene polyol contained in the skeleton of the polyurethane (a1) and the structure derived from the polyoxyalkylene polyol contained in the skeleton of the polyurethane (a2) may be the same or different. ..
- Polyisocyanate having a structure derived from the polyisocyanate contained in the skeletons of the polyurethane (a1) and the polyurethane (a2) a compound having a plurality of isocyanato groups is used, and it is preferable to use a diisocyanate.
- the diisocyanate include tolylene diisocyanate and its hydrogen additive, xylylene diisocyanate and its hydrogen additive, diphenylmethane diisocyanate and its hydrogen additive, 1,5-naphthylene diisocyanate and its hydrogen additive, hexamethylene diisocyanate, and trimethyl.
- Examples thereof include hexamethylene diisocyanate, tetramethylxylylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexyldiisocyanate, 1,3-bis (isocyanatemethyl) cyclohexane, norbornan diisocyanate and the like.
- polystyrene resin it is preferable to use an isophorone diisocyanate or a hydrogenated diphenylmethane diisocyanate from the viewpoint of controlling the light resistance of the polyurethane (A) synthesized using the polyisocyanate and the reactivity with the polyoxyalkylene polyol. .. It is more preferable to use a hydrogenated diphenylmethane diisocyanate in terms of reactivity with a polyoxyalkylene polyol.
- polyisocyanate having a structure derived from polyisocyanate examples include hydrogenated diphenylmethane diisocyanate (Desmodule W, manufactured by Sumika Covestrourethane) and isophorone diisocyanate (Desmodule I, manufactured by Sumika Covestrourethane). Can be mentioned.
- the polyisocyanate-derived structure contained in the skeletons of the polyurethane (a1) and the polyurethane (a2) may be of only one type, or may be a structure containing two or more types. Further, the structure derived from polyisocyanate contained in the skeleton of polyurethane (a1) and the structure derived from polyisocyanate contained in the skeleton of polyurethane (a2) may be the same or different.
- polyurethane (a1) and polyurethane (a2) can be synthesized at the same time.
- Polyurethane (A) can be efficiently produced, which is preferable.
- the proportion of polyurethane (a1) contained in polyurethane (A) is preferably 80 to 100%, more preferably 90 to 100%, and even more preferably 100% of polyurethane (A) on the basis of the number of molecules.
- the proportion of polyurethane (a2) contained in polyurethane (A) is preferably 0 to 20%, more preferably 0 to 10%, and even more preferably 0% of polyurethane (A) on the basis of the number of molecules.
- polyurethane (A) Of all the number of terminals contained in polyurethane (A) (total number of terminals of polyurethane (a1) and the number of terminals of polyurethane (a2) contained as needed), 90 to 100 based on the number of molecules. It is preferable that a (meth) acryloyl group is introduced into the%, more preferably 95 to 100%, still more preferably 100%. When the amount of the (meth) acryloyl group introduced is 90% or more based on the number of molecules among all the terminals contained in the polyurethane (A), it is obtained by curing the pressure-sensitive adhesive composition containing the polyurethane (A). The cohesive force of the cured product is sufficiently high.
- the ratio of the number of terminals into which the (meth) acryloyl group is introduced based on the number of molecules among all the number of terminals contained in polyurethane (A) is determined by the infrared absorption spectrum (IR) method and the nuclear magnetic resonance spectrum (NMR) method. It can be calculated using the result of analyzing the polyurethane (A) using the above.
- the ratio of the number of introduced terminals can be adjusted by the method for producing polyurethane (A) described later.
- the mass average molecular weight of the polyurethane (A) is preferably 30,000 to 200,000, more preferably 50,000 to 150,000, and even more preferably 60,000 to 100,000. ..
- the mass average molecular weight of the polyurethane (A) is 30,000 or more, the cured product obtained by curing the pressure-sensitive adhesive composition containing the polyurethane (A) has good flexibility. Further, when the mass average molecular weight of the polyurethane (A) is 200,000 or less, the pressure-sensitive adhesive composition containing the polyurethane (A) is easy to handle and has good workability.
- the mass average molecular weight of polyurethane (A) is a value in terms of polystyrene measured by gel permeation chromatography (GPC-101; Shodex (registered trademark) manufactured by Showa Denko KK) (hereinafter referred to as GPC).
- GPC gel permeation chromatography
- the measurement conditions of GPC are as follows. Column: LF-804 (manufactured by Showa Denko KK) Column temperature: 40 ° C Sample: 0.2 mass% tetrahydrofuran solution of polyurethane (A) Flow rate: 1 ml / min Eluent: Tetrahydrofuran Detector: RI detector (differential refractive index detector)
- the content of the polyurethane (A) in the pressure-sensitive adhesive composition of the present embodiment is preferably 20 to 50% by mass, more preferably 25 to 45% by mass, and 30 to 40% by mass. Is even more preferable.
- the content of the polyurethane (A) is 20% by mass or more, the cured product obtained by curing the pressure-sensitive adhesive composition has a sufficient cohesive force, and an excellent adhesive force can be obtained.
- the softness of the pressure-sensitive adhesive layer is within an appropriate range, and air bubbles are less likely to be caught between the pressure-sensitive adhesive layer and the adherend.
- the content of the polyurethane (A) is 50% by mass or less, the cured product obtained by curing the pressure-sensitive adhesive composition has sufficient flexibility. Therefore, the pressure-sensitive adhesive sheet using this cured product as the pressure-sensitive adhesive layer has good wettability with respect to the adherend.
- the (meth) acrylic monomer (B) is not particularly limited as long as it is a compound having a (meth) acryloyloxy group.
- the (meth) acrylic monomer (B) only one compound having a (meth) acryloyloxy group may be used alone, or two or more thereof may be mixed and used.
- a monofunctional (meth) acrylate may be used, a polyfunctional (meth) acrylate may be used, or a monofunctional (meth) acrylate and a polyfunctional (meth) acrylate. You may use both of.
- monofunctional (meth) acrylate means a (meth) acrylate having only one (meth) acryloyloxy group.
- polyfunctional in the polyfunctional (meth) acrylate means a (meth) acrylate having two or more (meth) acryloyloxy groups.
- the (meth) acrylic monomer (B) includes a monofunctional (meth) acrylate and a polyfunctional (meth) from the viewpoint of the cohesiveness of the cured product obtained by curing the pressure-sensitive adhesive composition and the curability of the pressure-sensitive adhesive composition. It is preferable to use it in combination with an acrylate, and it is more preferable to contain a monofunctional (meth) acrylate and a trifunctional or higher (meth) acrylate, in particular, a monofunctional (meth) acrylate and three (meth) acrylates. Most preferably, it contains a trifunctional (meth) acrylate having an acryloyloxy group.
- Examples of the monofunctional (meth) acrylate include cyclic alkyl (meth) acrylate such as alkyl (meth) acrylate and isobornyl (meth) acrylate, alkoxyalkyl (meth) acrylate, alkoxy (poly) alkylene glycol (meth) acrylate, and hydroxy.
- the pressure-sensitive adhesive layer of the sheet it tends to be in a more appropriate range, and therefore it is preferable to contain an alkyl (meth) acrylate.
- the alkyl (meth) acrylate it is more preferable to use an alkyl (meth) acrylate having an alkyl group having 4 to 10 carbon atoms.
- alkyl (meth) acrylate examples include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate.
- 2-ethylhexyl (meth) acrylate and / or n-butyl (meth) acrylate examples include 2-ethylhexyl (meth) acrylate and / or n-butyl (meth) acrylate.
- the polyfunctional (meth) acrylate is a compound other than polyurethane (A) and having a plurality of (meth) acryloyloxy groups.
- the polyfunctional (meth) acrylate it is preferable to use a poly (meth) acrylate of a polyol compound.
- Specific examples of the polyfunctional (meth) acrylate include polyethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, and tripropylene glycol.
- trimethylolpropane tri (meth) acrylate is preferably used as the polyfunctional (meth) acrylate from the viewpoint of curability of the pressure-sensitive adhesive
- both monofunctional (meth) acrylate and polyfunctional (meth) acrylate are contained as the (meth) acrylic monomer (B), when the total of the (meth) acrylic monomer (B) is 100 mol%, it is simple. It is preferable to contain 85 to 99 mol% of functional (meth) acrylate and 1 to 15 mol% of polyfunctional (meth) acrylate. In this case, the content of the monofunctional (meth) acrylate is more preferably 90 to 99 mol%, further preferably 95 to 98 mol%. Further, the content of the polyfunctional (meth) acrylate is more preferably 1 to 10 mol%, further preferably 2 to 5 mol%.
- the cured product obtained by curing the pressure-sensitive adhesive composition The fluidity is in a preferable range when the cured product is used as the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet. Therefore, the pressure-sensitive adhesive sheet using this cured product as the pressure-sensitive adhesive layer can obtain sufficient unevenness absorption, and when it is attached to an adherend having an uneven portion on the surface, it is placed between the adhesive sheet and the uneven portion of the adherend. It is preferable because voids are less likely to occur. Further, when the content of the monofunctional (meth) acrylate is 99 mol% or less, the adhesive sheet using the cured product of the adhesive composition as the adhesive layer is less likely to remain adhesive when peeled from the adherend. ,preferable.
- the content of the polyfunctional (meth) acrylate is 1 mol% or more, the cured product obtained by curing the pressure-sensitive adhesive composition It is preferable that the fluidity does not become too large. Further, when the content of the polyfunctional (meth) acrylate is 15 mol% or less, the fluidity of the cured product obtained by curing the pressure-sensitive adhesive composition is high when the cured product is used as the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet. It is a preferable range.
- the pressure-sensitive adhesive sheet using the cured product as the pressure-sensitive adhesive layer has sufficient unevenness absorbing property, and when it is attached to an adherend having an uneven portion on the surface, it is placed between the adhesive sheet and the uneven portion of the adherend. It is preferable because voids are less likely to occur.
- the content of the (meth) acrylic monomer (B) in the pressure-sensitive adhesive composition of the present embodiment is preferably 49 to 79% by mass, more preferably 53 to 73% by mass, and 56 to 66% by mass. It is more preferably%.
- the content of the (meth) acrylic monomer (B) is 49% by mass or more, the viscosity of the pressure-sensitive adhesive composition does not become too high and the coatability is excellent, which is preferable.
- the content of the (meth) acrylic monomer (B) is 79% by mass or less, the viscosity of the pressure-sensitive adhesive composition does not become too low, and the thickness of the coating film made of the pressure-sensitive adhesive composition can be easily controlled. ,preferable.
- the chain transfer agent (C) is contained in the pressure-sensitive adhesive composition for the purpose of controlling the storage elastic modulus, loss tangent, and gel fraction of the cured product obtained by curing the pressure-sensitive adhesive composition.
- a polyfunctional thiol can be preferably used as the chain transfer agent (C).
- a polyfunctional thiol is a compound having two or more mercapto groups in the molecule.
- the polyfunctional thiol is not particularly limited, and is, for example, 1,2-ethanedithiol, 1,4-bis (3-mercaptobutylyloxy) butane, tetraethylene glycol bis (3-mercaptopropionate), and trimethylolpropane.
- the chain transfer agent (C) it is preferable to use pentaerythritol tetrakis (3-mercaptobutyrate)
- the content of the chain transfer agent (C) in the pressure-sensitive adhesive composition of the present embodiment is preferably 0.5 to 5% by mass, more preferably 1 to 5% by mass, and 3 to 4. It is more preferably 5% by mass.
- the content of the chain transfer agent (C) is 0.5% by mass or more, the fluidity of the cured product obtained by curing the pressure-sensitive adhesive composition is high when the cured product is used as the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet. It is in a preferable range. Therefore, it is preferable that the pressure-sensitive adhesive sheet using the cured product as the pressure-sensitive adhesive layer has sufficient unevenness absorbing property and is less likely to generate voids between the cured product and the uneven portion of the adherend. When the content is 5% by mass or less, the adhesive sheet using the cured product of the adhesive composition as the adhesive layer is less likely to remain adhesive when peeled from the adherend, which is preferable.
- the photopolymerization initiator (D) is not particularly limited, but a photoradical polymerization initiator is preferable.
- the photopolymerization initiator (D) include a carbonyl-based photopolymerization initiator, a sulfide-based photopolymerization initiator, an acylphosphine oxide-based photopolymerization initiator, a quinone-based photopolymerization initiator, and a sulfochloride-based photopolymerization initiator.
- a thioxanthone-based photopolymerization initiator or the like can be used.
- photopolymerization initiators (D) it is preferable to use an acylphosphine oxide-based photopolymerization initiator from the viewpoint of transparency of the cured product obtained by photocuring the pressure-sensitive adhesive composition. It is preferable to use 2,4,6-trimethylbenzoyldiphenylphosphine oxide.
- the content of the photopolymerization initiator (D) in the pressure-sensitive adhesive composition of the present embodiment is preferably 0.01 to 5% by mass, more preferably 0.05 to 3% by mass, and 0. It is more preferably 1 to 2% by mass.
- the content of the photopolymerization initiator (D) is 0.01% by mass or more, the photocuring of the pressure-sensitive adhesive composition proceeds sufficiently.
- the content of the photopolymerization initiator (D) is 5% by mass or less, the low molecular weight component does not become too large during photocuring of the pressure-sensitive adhesive composition. Therefore, it is preferable that the pressure-sensitive adhesive sheet using the cured product of the pressure-sensitive adhesive composition as the pressure-sensitive adhesive layer is less likely to leave adhesive residue when peeled from the adherend.
- the pressure-sensitive adhesive composition of the present embodiment contains a polyurethane (A), a (meth) acrylic monomer (B), a chain transfer agent (C), and a photopolymerization initiator (D), if necessary. , Fatty acid ester (E) may be contained.
- the fatty acid ester (E) controls the adhesive force in the pressure-sensitive adhesive sheet using the cured product of the pressure-sensitive adhesive composition as the pressure-sensitive adhesive layer, and also has the adhesiveness (wetting property) and foam removal property (on the adherend) of the pressure-sensitive adhesive layer. It is contained for the purpose of improving the ease of removing air bubbles sandwiched when the adhesive sheets are bonded together.
- an ester of a fatty acid and an alkyl alcohol can be used, and from the viewpoint of compatibility with other components, a fatty acid having 8 to 18 carbon atoms and a branched hydrocarbon group having 3 to 18 carbon atoms It is preferable to use an ester selected from an ester with a monofunctional alcohol having the above, and an ester with an unsaturated fatty acid having 14 to 18 carbon atoms and an alcohol having 2 to 4 functionalities.
- ester of the fatty acid having 8 to 18 carbon atoms and the monofunctional alcohol having a branched hydrocarbon group having 3 to 18 carbon atoms examples include isostearyl laurate, isopropyl myristate, isosetyl myristate, octyldodecyl myristate, and isopropyl palmitate.
- isopropyl myristate, isopropyl palmitate, and 2-ethylhexyl stearate are preferably used, and isopropyl myristate and / or 2-ethylhexyl stearate is particularly preferable.
- esters of unsaturated fatty acids having 14 to 18 carbon atoms and alcohols having 2 to 4 functionalities include unsaturated fatty acids such as myristoleic acid, oleic acid, linoleic acid, linolenic acid, isostriatic acid, and isostearic acid, and ethylene.
- Esters with alcohols such as glycols, propylene glycols, glycerin, trimethylolpropane, pentaerythritol, and sorbitan can be mentioned.
- the content of the fatty acid ester (E) in the pressure-sensitive adhesive composition of the present embodiment is preferably 3 to 18% by mass, more preferably 5 to 15% by mass.
- the adhesive strength of the pressure-sensitive adhesive sheet using the cured product of the pressure-sensitive adhesive composition as the pressure-sensitive adhesive layer is in a preferable range as the pressure-sensitive adhesive sheet, and the pressure-sensitive adhesive layer Good laminate property and foam removal property.
- the content of the fatty acid ester (E) is 18% by mass or less, the fatty acid ester (E) is contained when the pressure-sensitive adhesive sheet using the cured product of the pressure-sensitive adhesive composition as the pressure-sensitive adhesive layer is peeled off from the adherend. It is preferable because the adhesive residue is less likely to occur.
- the pressure-sensitive adhesive composition of the present embodiment may contain a solvent, but is more preferably a solvent-free one that does not substantially contain a solvent.
- a solvent for example, a solvent can be used as a leveling agent and / or a softening agent.
- the pressure-sensitive adhesive composition of the present embodiment is solvent-free, excellent productivity can be obtained because the step of heating and drying the solvent can be omitted when forming the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet.
- the productivity improvement effect by omitting the step of heating and drying the solvent is remarkable. Therefore, it is preferable that there is no solvent.
- the meaning of "substantially free of solvent” in the pressure-sensitive adhesive composition means that the content of the solvent in the pressure-sensitive adhesive composition is 0 to 1% by mass, preferably 0 to 0. It is 5.5% by mass, more preferably 0 to 0.1% by mass.
- the pressure-sensitive adhesive composition of the present embodiment may contain other additives, if necessary, as long as the effects of the present invention are not impaired.
- Additives include, for example, plasticizers, surface lubricants, antioxidants, antioxidants, light stabilizers, UV absorbers, polymerization inhibitors, light stabilizers such as benzotriazoles, phosphate esters and others. Examples thereof include flame retardants, antistatic agents such as surfactants, and dyes.
- the pressure-sensitive adhesive composition of the present embodiment is photocurable, and the gel fraction of the cured product cured at an irradiation amount of 1000 mJ / cm 2 is 50 to 65 mass so that the thickness after curing is 150 ⁇ m. It is in the range of%.
- the gel fraction of the cured product cured at an irradiation amount of 1000 mJ / cm 2 was that of polyurethane (A), (meth) acrylic monomer (B), chain transfer agent (C), and photopolymerization initiator (D). Can be adjusted by controlling the content of the chain transfer agent (C) and / or the photopolymerization initiator (D) in the pressure-sensitive adhesive composition of the present embodiment containing the above.
- the cured product having a gel fraction of 50 to 65% by mass obtained by curing the pressure-sensitive adhesive composition of the present embodiment at an irradiation amount of 1000 mJ / cm 2 has sufficient adhesive strength and is less likely to cause adhesive residue. Excellent unevenness absorption. Therefore, the pressure-sensitive adhesive composition of the present embodiment is suitable as a material for a pressure-sensitive adhesive layer in a pressure-sensitive adhesive sheet used for applications in which an adherend having an uneven portion on the surface is attached and then peeled off.
- the gel fraction of the cured product obtained by curing the pressure-sensitive adhesive composition of the present embodiment at an irradiation amount of 1000 mJ / cm 2 is preferably 52% by mass or more.
- the gel fraction of the cured product is preferably 63% by mass or less.
- the pressure-sensitive adhesive sheet using the cured product having a gel fraction of less than 50% by mass as the pressure-sensitive adhesive layer tends to leave adhesive residue by peeling off after being attached to the adherend.
- a cured product having a gel fraction of more than 65% by mass has insufficient fluidity when used as an adhesive layer of an adhesive sheet. Therefore, when a pressure-sensitive adhesive sheet using a cured product having a gel fraction of more than 65% by mass as an adhesive layer is attached to an adherend having an uneven portion on the surface, it is placed between the adhesive sheet and the uneven portion of the adherend. Voids are likely to occur.
- the gel fraction of the cured product obtained by curing the pressure-sensitive adhesive composition at an irradiation amount of 1000 mJ / cm 2 is measured as follows. First, a 75 ⁇ m-thick peeling PET film (manufactured by Higashiyama Film Co., Ltd., trade name: Clean Sepa (trademark) HY-S10-2) is adhered using an applicator so that the thickness after curing is 150 ⁇ m. Apply the agent composition. Next, the coated surface of the pressure-sensitive adhesive composition is covered with a silicone-based ultra-light peeling PET film (manufactured by Toyobo Co., Ltd., product name: E7006) having a thickness of 75 ⁇ m.
- a silicone-based ultra-light peeling PET film manufactured by Toyobo Co., Ltd., product name: E7006
- the irradiation distance is 25 cm
- the lamp moving speed is 1.0 m / min
- the irradiation amount is 1000 mJ / cm 2 .
- Ultraviolet rays are irradiated through the ultra-light peeling PET film to cure the pressure-sensitive adhesive composition to obtain a cured product (adhesive layer).
- the cured product obtained by curing the pressure-sensitive adhesive composition of the present embodiment at an irradiation amount of 1000 mJ / cm 2 so that the thickness after curing is 150 ⁇ m has a storage elastic modulus at 25 ° C. measured at a frequency of 1 Hz. 0 ⁇ a 10 4 ⁇ 1.0 ⁇ 10 5, it is preferable loss tangent is 0.25 to 0.55.
- the storage elastic modulus and loss positive contact at 25 ° C. of the cured product cured at an irradiation amount of 1000 mJ / cm 2 measured at a frequency of 1 Hz are the chain transfer agent (C) contained in the pressure-sensitive adhesive composition and / or the initiation of photopolymerization.
- the content of the agent (D) can be adjusted by controlling the content of the agent (D). More specifically, when the content of the chain transfer agent (C) and / or the photopolymerization initiator (D) is increased, the storage elastic modulus decreases and the loss tangent increases. Further, when the content of the chain transfer agent (C) and / or the photopolymerization initiator (D) is reduced, the storage elastic modulus becomes high and the loss tangent becomes small.
- the storage modulus is a 1.0 ⁇ 10 4 ⁇ 1.0 ⁇ 10 5
- the loss tangent is 0
- the cured product of .25 to 0.55 has good flexibility and fluidity. Therefore, when an adhesive sheet using this cured product as an adhesive layer is attached to a work (adhesive body) such as a semiconductor wafer having an uneven portion such as a bump, a gap is provided between the uneven portion and the adhesive sheet. Can be prevented from occurring.
- a storage modulus at 25 ° C. was measured at a frequency 1Hz cured product obtained by curing the adhesive composition by irradiation amount 1000 mJ / cm 2 of the present embodiment is more preferably 2.0 ⁇ 10 4 or more , further preferably 3.0 ⁇ 10 4 or more. Further, the storage elastic modulus is more preferably 9.0 ⁇ 10 4 or less, further preferably 8.0 ⁇ 10 4 or less.
- the storage modulus is 1.0 ⁇ 10 4 or more, it is not too soft when used as adhesive layer of the adhesive sheet. Therefore, the cured product is storage modulus 1.0 ⁇ 10 4 or more, the pressure-sensitive adhesive sheet used as an adhesive layer may be peeled off after attached to an adherend, adhesive residue is less likely to occur, preferably. Further, the cured product above storage elastic modulus is 1.0 ⁇ 10 5 or less, when used as an adhesive layer of the adhesive sheet, having a good flexibility.
- the loss tangent at 25 ° C. measured at a frequency of 1 Hz of the cured product obtained by curing the pressure-sensitive adhesive composition of the present embodiment at an irradiation amount of 1000 mJ / cm 2 is more preferably 0.30 or more. Further, the loss tangent is more preferably 0.50 or less.
- the cured product having a loss tangent of 0.25 or more has good fluidity when used as an adhesive layer of an adhesive sheet. Therefore, when a pressure-sensitive adhesive sheet using a cured product having a loss tangent of 0.25 or more as an adhesive layer is attached to an adherend having an uneven portion on the surface, it is between the adherend and the uneven portion of the adherend. It is preferable because voids are less likely to be generated in the air. Further, the cured product having the loss tangent of 0.55 or less does not have too large fluidity when used as the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet. Therefore, a pressure-sensitive adhesive sheet using a cured product having a loss tangent of 0.55 or less as a pressure-sensitive adhesive layer is preferable because adhesive residue is unlikely to occur even if it is peeled off after being attached to an adherend.
- the storage elastic modulus and loss tangent at 25 ° C. measured at a frequency of 1 Hz of the cured product obtained by curing the pressure-sensitive adhesive composition at an irradiation amount of 1000 mJ / cm 2 are measured by the following methods.
- the pressure-sensitive adhesive composition is cured in the same manner as in the method for measuring the gel fraction described above to prepare a sheet having a cured product (adhesive layer) having a thickness of 150 ⁇ m.
- the peeling PET film and the ultra-light peeling PET film are peeled from the pressure-sensitive adhesive layer of the sheet having the cured product (adhesive layer).
- 10 peeled adhesive layers having a thickness of 150 ⁇ m are laminated to form a laminated sheet having a thickness of 1.5 mm.
- a square sheet having a length of 8 mm and a width of 8 mm is cut out from the obtained laminated sheet and used as a measurement sample.
- a rotary viscoelasticity measuring device (rheometer) (manufactured by TA Instruments, product name "AR2000" was used, and the frequency was -20 to 1 Hz (6.28 rad / sec).
- the storage elastic modulus and loss elastic modulus at 120 ° C. are measured in the shear mode, and the storage elastic modulus and loss tangent at 25 ° C. are calculated.
- the method for producing the pressure-sensitive adhesive composition of the present embodiment will be described in detail with reference to an example.
- the polyurethane (A) will be described with reference to a preferable synthetic method.
- polyurethane (A) such as (meth) acrylic monomer (B), chain transfer agent (C), photopolymerization initiator (D), fatty acid ester (E), etc. Since commercially available products can be easily purchased and the synthesis method differs depending on the type of compound used as each component, the description of the synthesis method will be omitted.
- the reaction between the hydroxy group and the isocyanato group is carried out in any of the steps in the presence of an organic solvent inert to the isocyanato group, such as dibutyltin dilaurate, dibutyltin diethylhexoate. This is carried out using a urethanization catalyst such as dioctyltin dilaurate.
- the reaction between the hydroxy group and the isocyanato group is preferably carried out continuously at 30 to 100 ° C. for 1 to 5 hours in any of the steps.
- the amount of the urethanization catalyst used is preferably 50 to 500 mass ppm with respect to the total mass of the reactant (raw material).
- polyoxyalkylene polyol and polyisocyanate are mixed at a ratio in which the isocyanato group weight (molecular number standard, the same applies hereinafter) is larger than the hydroxy group weight (molecular number standard, the same applies hereinafter).
- the polyoxyalkylene polyol is reacted with the polyisocyanate to synthesize a polyurethane having an isocyanato group at the terminal as a precursor of the polyurethane (A).
- Specific examples of the polyoxyalkylene polyol and the polyisocyanate used as raw materials are as illustrated in the section of polyurethane (A).
- the molecular weight (degree of polymerization) of the polyurethane having an isocyanato group at the terminal can be adjusted by adjusting the ratio of the isocyanato group amount to the hydroxy group amount contained in the raw material. Specifically, the smaller the excess amount of the isocyanato group with respect to the hydroxy group amount, the larger the molecular weight of the polyurethane having an isocyanato group at the terminal. Further, the larger the excess amount of the isocyanato group with respect to the hydroxy group amount, the smaller the molecular weight of the polyurethane having an isocyanato group at the terminal.
- the mass average molecular weight of the target polyurethane (A) is adjusted by adjusting the molecular weight of the polyurethane having an isocyanato group at the terminal.
- a polyurethane having an isocyanato group at the terminal is reacted with a compound having a hydroxy group and a (meth) acryloyl group to have a structure containing a polyoxyalkylene polyol-derived structure and a polyisocyanate-derived structure.
- Polyurethane (A) containing polyurethane (a1) having a (meth) acryloyl group at the end of is produced.
- the terminal (meth) acryloyl group of the produced polyurethane (A) is preferably a part of the (meth) acryloyloxy group.
- the compound having a hydroxy group and a (meth) acryloyl group is not particularly limited, but is a hydroxyalkyl such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate.
- Examples thereof include monool having a (meth) acryloyl group derived from various polyols such as.
- These compounds having a hydroxy group and a (meth) acryloyl group may be used alone or in combination of two or more.
- 2-hydroxyethyl (meth) is obtained from the viewpoint of reactivity with the isocyanato group of polyurethane having an isocyanato group at the terminal and photocurability of the pressure-sensitive adhesive composition.
- polyurethane (A) has an isocyanato group at the terminal in combination with a compound having a hydroxy group and a (meth) acryloyl group and an alkyl alcohol having no (meth) acryloyl group and having one hydroxy group. It may be produced by reacting with polyurethane.
- the alkyl alcohol may be any as long as it does not have a (meth) acryloyl group and has one hydroxy group, and linear, branched, alicyclic alkyl alcohols and the like can be used and is not particularly limited. ..
- the above alkyl alcohol may be used alone or in combination of two or more.
- Polyurethane (A) is obtained by reacting a compound having a hydroxy group and a (meth) acryloyl group, an alkyl alcohol having no (meth) acryloyl group and having one hydroxy group, and a polyurethane having an isocyanato group at the terminal.
- the amount of (meth) acryloyl group introduced into polyurethane having an isocyanato group at the terminal can be adjusted by producing.
- a polyurethane (A) containing a plurality of types of polyurethane having different amounts of introduced (meth) acryloyl groups at the ends is produced.
- the plurality of types of polyurethanes include polyurethanes (a1) having a plurality of (meth) acryloyl groups at the ends.
- the plurality of types of polyurethane include not only polyurethane (a1) but also polyurethane in which at least a part of the plurality of ends has a structure derived from the above alkyl alcohol.
- the produced plurality of types of polyurethanes include polyurethanes in which at least some of the plurality of ends do not have a (meth) acryloyl group. Furthermore, among the plurality of types of polyurethane produced, polyurethane (a2) having a (meth) acryloyl group at only one terminal may be included.
- reaction between the hydroxy group and the isocyanato group is preferably carried out continuously at 30 to 100 ° C. for 1 to 5 hours in any of the steps.
- the amount of the urethanization catalyst used is preferably 50 to 500 mass ppm with respect to the total mass of the reactant (raw material).
- polyurethane having a hydroxy group at the terminal is synthesized as a precursor of polyurethane (A). Specifically, first, the polyoxyalkylene polyol and the polyisocyanate are charged at a ratio in which the hydroxy group amount (based on the number of molecules, the same below) is larger than the amount of the isocyanato group (based on the number of molecules, the same below). Then, the polyoxyalkylene polyol is reacted with the polyisocyanate to synthesize a polyurethane having a hydroxy group at the terminal as a precursor of the polyurethane (A).
- the molecular weight (degree of polymerization) of the polyurethane having a hydroxy group at the terminal can be adjusted by adjusting the ratio of the hydroxy group amount to the isocyanato group amount contained in the raw material. Specifically, the smaller the excess amount of the hydroxy group amount with respect to the isocyanato group amount, the larger the molecular weight of the polyurethane having a hydroxy group at the terminal. Further, the larger the excess amount of the hydroxy group amount with respect to the isocyanato group amount, the smaller the molecular weight of the polyurethane having a hydroxy group at the terminal.
- the mass average molecular weight of the target polyurethane (A) is adjusted by adjusting the molecular weight of the polyurethane having a hydroxy group at the terminal.
- a polyurethane having a hydroxy group at the terminal is reacted with a compound having an isocyanato group and a (meth) acryloyl group to have a structure containing a polyoxyalkylene polyol-derived structure and a polyisocyanate-derived structure.
- Polyurethane (A) containing polyurethane (a1) having a (meth) acryloyl group at the end of is produced.
- the terminal (meth) acryloyl group of the produced polyurethane (A) is preferably a part of the (meth) acryloyloxy group.
- the compound having an isocyanato group and a (meth) acryloyl group is not particularly limited, but is limited to 2- (meth) acryloyloxyethyl isocyanate, 2- (meth) acryloyloxypropyl isocyanate, and 1,1-bis (acryloyloxymethyl) ethyl. Examples thereof include isocyanate. Examples of commercially available compounds having an isocyanato group and a (meth) acryloyl group include Karenz MOI (registered trademark) and Karenz AOI (registered trademark) manufactured by Showa Denko KK. These compounds having an isocyanato group and a (meth) acryloyl group may be used alone or in combination of two or more.
- 2- (meth) acryloyl from the viewpoint of reactivity with the hydroxy group of polyurethane having a hydroxy group at the terminal and photocurability of the pressure-sensitive adhesive composition. It is preferable to use oxyethyl isocyanate.
- the polyurethane (A) has a hydroxy group at the terminal in combination with a compound having an isocyanato group and a (meth) acryloyl group and an alkyl isocyanate having no (meth) acryloyl group and having one isocyanato group. It may be produced by reacting with polyurethane.
- the alkyl isocyanate may be any as long as it does not have a (meth) acryloyl group and has one isocyanato group, and linear type, branched type, alicyclic type alkyl isocyanate and the like can be used and is not particularly limited. ..
- the above alkyl isocyanate may be used alone or in combination of two or more.
- Polyurethane (A) is obtained by reacting a compound having an isocyanato group and a (meth) acryloyl group, an alkyl isocyanate having no (meth) acryloyl group and having one isocyanato group, and a polyurethane having a hydroxy group at the terminal.
- the amount of (meth) acryloyl group introduced into polyurethane having a hydroxy group at the terminal can be adjusted by producing.
- a polyurethane (A) containing a plurality of types of polyurethane having different amounts of introduced (meth) acryloyl groups at the ends is produced.
- the plurality of types of polyurethanes include polyurethanes (a1) having a plurality of (meth) acryloyl groups at the ends.
- the plurality of types of polyurethane include not only polyurethane (a1) but also polyurethane in which at least a part of the plurality of ends has a structure derived from the above alkyl isocyanate.
- the produced plurality of types of polyurethanes include polyurethanes in which at least some of the plurality of ends do not have a (meth) acryloyl group. Furthermore, among the plurality of types of polyurethane produced, polyurethane (a2) having a (meth) acryloyl group at only one terminal may be included.
- the pressure-sensitive adhesive composition of the present embodiment contains the polyurethane (A) obtained by the above synthetic method, the (meth) acrylic monomer (B), the chain transfer agent (C), and the photopolymerization initiator (D).
- A polyurethane
- B the (meth) acrylic monomer
- C the chain transfer agent
- D the photopolymerization initiator
- the method of mixing each component contained in the pressure-sensitive adhesive composition of the present embodiment is not particularly limited, and can be carried out by using, for example, a stirring device equipped with a stirring blade such as a homodisper or a paddle blade. ..
- the pressure-sensitive adhesive composition of the present embodiment contains a polyurethane (A), a (meth) acrylic monomer (B), a chain transfer agent (C), and a photopolymerization initiator (D), and the polyurethane (A) contains the polyurethane (A).
- Polyurethane (a1) having a skeleton containing a structure derived from polyoxyalkylene polyol and a structure derived from polyisocyanate and having a (meth) acryloyl group at a plurality of ends, and photocured at an irradiation dose of 1000 mJ / cm 2 .
- the gel content of the cured product is 50 to 65% by mass.
- the pressure-sensitive adhesive composition of the present embodiment is suitable as a material for a pressure-sensitive adhesive layer in a pressure-sensitive adhesive sheet used for applications in which an adherend having an uneven portion on the surface is attached and then peeled off.
- the method for producing the pressure-sensitive adhesive sheet of the present embodiment is not particularly limited, and it can be produced by using a known method. For example, an adhesive composition is applied onto a sheet-shaped base material, and a separator is laminated to form a laminate. Then, the pressure-sensitive adhesive composition is irradiated with ultraviolet rays via a separator to photo-cure the pressure-sensitive adhesive composition. As a result, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer made of a cured product of the pressure-sensitive adhesive composition formed on the base material can be obtained.
- the method of applying the pressure-sensitive adhesive composition to the base material is not particularly limited and can be appropriately selected.
- various coaters 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, and a direct coater are used. Examples thereof include a method to be used and a screen printing method.
- Examples of the light source for photocuring the pressure-sensitive adhesive composition include black light, low-pressure mercury lamp, high-pressure mercury lamp, ultra-high pressure mercury lamp, metal halide lamp, xenon lamp and the like.
- the light irradiation intensity may be such that the pressure-sensitive adhesive composition can be sufficiently cured and the gel fraction of the cured product is in the range of 50 to 65% by mass, for example, 50 to 3000 mW / cm. It is preferably 2 . If the light irradiation intensity is weak, it takes time to cure and the productivity decreases. Further, the light irradiation intensity is more preferably adjusted so that the storage elastic modulus and the loss tangent value at 25 ° C. measured at a frequency of 1 Hz are within a desired range.
- the pressure-sensitive adhesive composition is irradiated with ultraviolet rays via a transparent separator, but when the substrate and the separator are transparent, the ultraviolet rays may be irradiated from either the separator side or the substrate side.
- the pressure-sensitive adhesive sheet of the present embodiment can be used for applications where it is attached to an adherend having an uneven portion on the surface and then peeled off. Specifically, it can be suitably used as an adhesive sheet that is attached to the bump-formed surface of the semiconductor wafer to protect the surface of the semiconductor wafer and is peeled off after a predetermined processing step.
- the peel strength (adhesive strength) of the pressure-sensitive adhesive sheet is such that the semiconductor wafer is a pressure-sensitive adhesive sheet in a semiconductor device processing process such as a back grind process. It needs to be strong enough to be firmly fixed to the wafer.
- the strength needs to be such that the parts of the semiconductor device are not damaged. From these viewpoints, the peeling strength of the pressure-sensitive adhesive sheet used in the above application is such that the peeling speed is 0.3 m / min.
- the thickness of the pressure-sensitive adhesive layer is 50 to 200 ⁇ m, it is preferably 10 to 300 gf / 25 mm, more preferably 15 to 200 gf / 25 mm, and further preferably 20 to 150 gf / 25 mm. preferable.
- a specific method for measuring the peel strength of the pressure-sensitive adhesive sheet will be described later in Examples.
- the pressure-sensitive adhesive sheet of the present embodiment has a pressure-sensitive adhesive layer made of a cured product of the pressure-sensitive adhesive composition of the present embodiment on one side of a sheet-like base material. Therefore, the adhesive sheet of the present embodiment has sufficient adhesive strength, is less likely to leave adhesive residue on which the adhesive layer is transferred to the adherend after the adhesive sheet is peeled off, and is excellent in unevenness absorption. .. Therefore, the pressure-sensitive adhesive sheet of the present embodiment is suitable for applications where it is attached to an adherend having an uneven portion on the surface and then peeled off.
- the pressure-sensitive adhesive sheet of the present embodiment can be suitably used as, for example, a pressure-sensitive adhesive sheet that is attached when performing a back grind step of a semiconductor wafer having an uneven portion composed of bumps on the surface and is peeled off after the back grind step.
- the semiconductor wafer is fixed with sufficient adhesive force by the adhesive sheet of the present embodiment, and voids are less likely to occur between the adhesive sheet attached to the semiconductor wafer and the periphery of the bump. Therefore, it is possible to prevent the water used in the back grind process from entering the gap between the adhesive sheet and the periphery of the bump and contaminating the semiconductor wafer. Further, after the back grind step, adhesive residue is less likely to occur around the bumps of the semiconductor wafer from which the adhesive sheet has been peeled off, which is preferable.
- the obtained polyurethane (A-1) was analyzed using the infrared absorption spectrum (IR) method. As a result, no peak derived from the isocyanato group was observed. Therefore, it was confirmed that the polyurethane (A-1) is a polyurethane (a1) in which an acryloyloxy group is introduced at all terminals.
- IR infrared absorption spectrum
- the obtained polyurethane (A-2) was analyzed using the infrared absorption spectrum (IR) method. As a result, no peak derived from the isocyanato group was observed. Therefore, it was confirmed that the polyurethane (A-2) is a polyurethane (a1) in which an acryloyloxy group is introduced at all terminals.
- PE1 Pentaerythritol tetrakis (3-mercaptobutyrate) (manufactured by Showa Denko KK)
- NR1 1,3,5-Tris (3-mercaptobutyloxyethyl) -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -Trione (manufactured by Showa Denko KK)
- TPO Omnirad TPO H): 2,4,6-trimethylbenzoyldiphenylphosphine oxide (manufactured by IGM Resins BV)
- Exepearl IPM Isopropyl myristate (manufactured by Kao Corporation)
- Exepearl EH-S 2-ethylhexyl stearate (manufactured by Kao Corporation)
- a PET film having a thickness of 50 ⁇ m manufactured by Toyobo Co., Ltd., trade name: ester (trademark) film E5100 was prepared. Then, the pressure-sensitive adhesive composition of Example 1 was applied onto the corona-treated surface of the base material using an applicator so that the thickness after curing was 150 ⁇ m.
- a silicone-based ultra-light peeling PET film manufactured by Toyobo Co., Ltd., product name: E7006
- a silicone-based ultra-light peeling PET film having a thickness of 75 ⁇ m was attached to the coated surface of the pressure-sensitive adhesive composition using a rubber roller as a separator.
- an ultraviolet irradiation device manufactured by Eye Graphics Co., Ltd., UV irradiation device 3 kW, high-pressure mercury lamp
- the pressure-sensitive adhesive composition was photocured by irradiating with ultraviolet rays under the condition of an irradiation amount of 1000 mJ / cm 2 .
- the pressure-sensitive adhesive sheet of Example 1 in which the pressure-sensitive adhesive layer, which is a cured product of the pressure-sensitive adhesive composition, and the separator were laminated on the base material was obtained.
- the pressure-sensitive adhesive compositions of Examples 2 to 5 and Comparative Examples 1 to 5 are used in the same manner as the pressure-sensitive adhesive sheet of Example 1. , Created an adhesive sheet. As a result, the adhesive sheets of Examples 2 to 5 and Comparative Examples 2 to 4 were obtained. However, with respect to the pressure-sensitive adhesive compositions of Comparative Example 1 and Comparative Example 5, a pressure-sensitive adhesive layer made of a cured product of the pressure-sensitive adhesive composition could not be formed due to poor curing.
- the adhesive sheet was cut into a size of 25 mm in length and 50 mm in width, and the separator was peeled off to expose the adhesive layer. Then, the surface of the exposed pressure-sensitive adhesive layer and the bumps of a wafer with bumps (WALTS-TEG FC150SCJY LF (PI) manufactured by Waltz, bump height: 75 ⁇ m, bump size: diameter 90 ⁇ m) were placed facing each other. Then, a rubber roller (diameter: 85 mm, width: 50 mm) having a mass of 2 kg (load 19.6 N) is reciprocated three times at a speed of 10 mm / sec on the base material of the adhesive sheet to separate the adhesive sheet and the bumped wafer. I pasted them together.
- WALTS-TEG FC150SCJY LF (PI) manufactured by Waltz, bump height: 75 ⁇ m, bump size: diameter 90 ⁇ m
- the adhesive sheet was cut into a size of 25 mm in length and 50 mm in width, and the separator was peeled off to expose the adhesive layer. Then, the surface of the exposed pressure-sensitive adhesive layer was placed facing the bumps of a wafer with bumps (WALTS-TEG FC150SCJY LF (PI) manufactured by Waltz, bump height: 75 ⁇ m, bump size: diameter 90 ⁇ m). Then, a rubber roller (diameter: 85 mm, width: 50 mm) having a mass of 2 kg (load 19.6 N) is reciprocated three times at a speed of 10 mm / sec on the base material of the adhesive sheet to separate the adhesive sheet and the bumped wafer. I pasted them together.
- the bumped wafer bonded to the adhesive sheet was left at 23 ° C. for 24 hours, and then the adhesive sheet was placed at approximately 2 m / min. It was peeled off by hand at a moderate speed. Then, the surface of the bumped wafer was observed with a digital optical microscope (RH-2000 manufactured by Hirox Co., Ltd.), and the presence or absence of adhesive residue was evaluated according to the following criteria. The results are shown in Table 1 or 2. "Standard" ⁇ (Yes): There is no adhesive residue around the bump. ⁇ (impossible): There is adhesive residue around the bump.
- the adhesive sheets of Examples 1 to 5 having a gel fraction of 50 to 65% by mass all have a peeling force of 10 gf / 25 mm or more and have sufficient adhesive force. It was a thing.
- the adhesive sheets of Examples 1 to 5 were all evaluated as " ⁇ (possible)" for unevenness absorption and adhesive residue.
- the present invention can provide an adhesive sheet having sufficient adhesive strength, less likely to leave adhesive residue to which the adhesive layer is transferred to the adherend after the adhesive sheet is peeled off, and having excellent unevenness absorption. it can.
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Abstract
Description
本願は、2019年7月29日に、日本に出願された特願2019-138812号に基づき優先権を主張し、その内容をここに援用する。
しかしながら、従来の粘着シートは、十分な粘着力を有し、かつ糊残りが生じにくく、しかも凹凸吸収性に優れるものではなかった。このため、従来の粘着シートを用いる場合、半導体ウエハに対する十分な粘着力および凹凸吸収性を得るために、粘着シートの粘着剤層とは別に凹凸吸収層を設けたり、粘着剤層を加熱して軟化させたりする必要があった。
また、本発明は、十分な粘着力を有し、かつ糊残りが生じにくく、しかも凹凸吸収性に優れる硬化物が得られ、粘着シートの粘着剤層の材料として好適な粘着剤組成物を提供することを目的とする。
[1] 少なくともシート状の基材と、前記基材の片面に形成された粘着剤層とを有する粘着シートであって、
前記粘着剤層は、粘着剤組成物の硬化物からなり、ゲル分率が50~65質量%であり、
前記粘着剤組成物は、ポリウレタン(A)と、(メタ)アクリロイルオキシ基を有する化合物からなる(メタ)アクリルモノマー(B)と、連鎖移動剤(C)と、光重合開始剤(D)とを含み、
前記ポリウレタン(A)が、ポリオキシアルキレンポリオール由来の構造およびポリイソシアネート由来の構造を含む骨格を有し、2つ以上の末端に(メタ)アクリロイル基を有するポリウレタン(a1)を含むことを特徴とする粘着シート。
[2] 前記粘着剤層は、周波数1Hzで測定した25℃における貯蔵弾性率が1.0×104~1.0×105であり、
かつ、周波数1Hzで測定した25℃における損失正接が0.25~0.55である、[1]に記載の粘着シート。
[3] 前記粘着剤層の厚みが50~500μmである、[1]または[2]に記載の粘着シート。
[4] ポリウレタン(A)と、(メタ)アクリロイルオキシ基を有する化合物からなる(メタ)アクリルモノマー(B)と、連鎖移動剤(C)と、光重合開始剤(D)とを含み、
前記ポリウレタン(A)が、ポリオキシアルキレンポリオール由来の構造およびポリイソシアネート由来の構造を含む骨格を有し、2つ以上の末端に(メタ)アクリロイル基を有するポリウレタン(a1)を含み、
照射量1000mJ/cm2で光硬化させた硬化物のゲル分率が50~65質量%であることを特徴とする、粘着剤組成物。
[5] 前記硬化物は、周波数1Hzで測定した25℃における貯蔵弾性率が1.0×104~1.0×105であり、
かつ、周波数1Hzで測定した25℃における損失正接が0.25~0.55である、[4]に記載の粘着剤組成物。
[7] 前記(メタ)アクリルモノマー(B)の合計を100モル%としたときに、前記単官能(メタ)アクリレートを85~99モル%、前記多官能(メタ)アクリレートを1~15モル%含有する、[6]に記載の粘着剤組成物。
[9] 前記ポリウレタン(A)を20~50質量%、
前記(メタ)アクリルモノマー(B)を49~79質量%、
前記連鎖移動剤(C)を0.5~5質量%、
前記光重合開始剤(D)を0.01~5質量%含む、[4]~[8]のいずれかに記載の粘着剤組成物。
[10] 更に脂肪酸エステル(E)を含有する、[4]~[9]のいずれかに記載の粘着剤組成物。
<粘着シート>
本実施形態の粘着シートは、シート状の基材と、基材の片面に形成された粘着剤層とを有する。粘着剤層は、後述する粘着剤組成物の硬化物からなる。
さらに、基材の粘着剤層が形成される面には、必要に応じて、酸処理、アルカリ処理、プライマー処理、コロナ処理、プラズマ処理、紫外線処理、オゾン処理等の易接着処理が施されていてもよい。
これに対し、ゲル分率が50質量%未満であると、粘着シートを被着体に貼付した後に剥離することにより、糊残りが生じやすい。また、ゲル分率が65質量%を超えると、粘着シートの粘着剤層として用いた場合の流動性が不十分となる傾向がある。このため、粘着シートを、表面に凹凸部分を有する被着体に送付した場合に、被着体の凹凸部分との間に空隙が発生しやすい。
粘着剤層のゲル分率は、例えば、以下に示す方法により測定できる。
粘着シートから縦8cm、横8cmの正方形シートを切り出し、得られた正方形シートの粘着剤層から基材を剥離する。そして、正方形シートから剥離した粘着剤層を、測定用サンプルとする。得られた測定用サンプルは、後述する粘着剤組成物の硬化物からなる測定用サンプルのゲル分率の測定方法と同様の方法を用いて測定できる。
上記貯蔵弾性率が1.0×104以上である粘着剤層は、柔らかすぎることがない。このため、貯蔵弾性率が1.0×104以上である粘着剤層を有する粘着シートは、被着体に貼付した後に剥離しても、より一層糊残りが生じにくく、好ましい。また、上記貯蔵弾性率が1.0×105以下である粘着剤層は、良好な柔軟性を有する。このため、貯蔵弾性率が1.0×105以下の粘着剤層を有する粘着シートを、表面に凹凸部分を有する被着体に貼付した場合には、より一層、被着体の凹凸部分との間に空隙が発生しにくく、好ましい。
上記損失正接が0.25以上である粘着剤層は、良好な流動性を有する。このため、損失正接が0.25以上の粘着剤層を有する粘着シートを、表面に凹凸部分を有する被着体に貼付した場合には、被着体の凹凸部分との間に空隙が発生しにくく、好ましい。また、上記損失正接が0.55以下である粘着剤層は、流動性が大きすぎることがない。このため、損失正接が0.55以下である粘着剤層を有する粘着シートは、被着体に貼付した後に剥離しても、糊残りが生じにくく、好ましい。
粘着剤層の貯蔵弾性率および損失正接は、例えば、以下に示す方法により測定できる。まず、粘着シートから基材を剥離する。そして、基材を剥離した粘着剤層を積層して、厚みが1~2mmの範囲内である積層シートとする。得られた積層シートから縦8mm、横8mmの正方形シートを切り出し、測定用サンプルとする。得られた測定用サンプルは、後述する粘着剤組成物の硬化物からなる測定用サンプルの貯蔵弾性率および損失正接の測定方法と同様の方法を用いて測定できる。
本実施形態の粘着シートの有する粘着剤層は、粘着剤組成物の硬化物からなる。以下、本実施形態の粘着シートの有する粘着剤層の材料として使用した粘着剤組成物について、詳細に説明する。
本実施形態の粘着剤組成物は、ポリウレタン(A)と、(メタ)アクリルモノマー(B)と、連鎖移動剤(C)と、光重合開始剤(D)とを含む。
ポリウレタン(A)は、ポリウレタン(a1)を含む。ポリウレタン(A)には、ポリウレタン(a1)だけでなく、粘着剤組成物の硬化物における凝集力を調節する目的で、後述するポリウレタン(a2)が含まれていてもよい。ポリウレタン(A)には、ポリウレタン(a1)と、必要に応じて含有されるポリウレタン(a2)以外の成分は含まれないことが好ましい。
ポリウレタン(a1)は、ポリオキシアルキレンポリオール由来の構造およびポリイソシアネート由来の構造を含む骨格を有する。また、ポリウレタン(a1)は、2つ以上の、すなわち複数の末端に(メタ)アクリロイル基を有する。ポリウレタン(a1)の有する末端の(メタ)アクリロイル基は、(メタ)アクリロイルオキシ基の一部であることが好ましい。
また、本発明において、(メタ)アクリロイル基とは、化学式CH2=CH-CO-で表される官能基、および化学式CH2=C(CH3)-CO-で表される官能基から選択される一種以上を意味する。
ポリウレタン(a2)は、ポリウレタン(a1)と同様に、ポリオキシアルキレンポリオール由来の構造およびポリイソシアネート由来の構造を含む骨格を有する。ポリウレタン(a2)は、ポリウレタン(a1)と異なり、1つの末端のみに(メタ)アクリロイル基を有する。ポリウレタン(a2)の有する末端の(メタ)アクリロイル基は、(メタ)アクリロイルオキシ基の一部であることが好ましい。ポリウレタン(a2)の有する(メタ)アクリロイル基を有さない末端は、イソシアナト基、アルキルアルコール由来の構造、アルキルイソシアネート由来の構造から選ばれるいずれかを有することが好ましく、アルキルアルコール由来の構造を有することがより好ましい。
ポリウレタン(a1)およびポリウレタン(a2)の骨格に含まれるポリオキシアルキレンポリオール由来の構造となるポリオキシアルキレンポリオールとしては、炭素数2~4のアルキレン鎖を有するものであることが好ましい。具体例としては、ポリオキシエチレンポリオール、ポリオキシプロピレンポリオール、ポリオキシブチレンポリオールなどが挙げられる。
ポリオキシアルキレンポリオール由来の構造となるポリオキシアルキレンポリオールは、末端に2つまたは3つの水酸基を有するもの(ジオール型またはトリオール型のポリオキシアルキレンポリオール)であることが好ましく、ポリオキシアルキレングリコール(ジオール型)であることがより好ましく、炭素数3のアルキレン鎖を有するポリプロピレングリコールであることが特に好ましい。
ポリウレタン(a1)およびポリウレタン(a2)は、2種以上の異なるポリオキシアルキレンポリオール由来の構造が、ポリイソシアネート由来の構造を挟んで結合された構造を有していてもよい。
ポリウレタン(a1)の骨格に含まれるポリオキシアルキレンポリオール由来の構造と、ポリウレタン(a2)の骨格に含まれるポリオキシアルキレンポリオール由来の構造とは、同じであってもよいし、異なっていてもよい。
ポリウレタン(a1)およびポリウレタン(a2)の骨格に含まれるポリイソシアネート由来の構造となるポリイソシアネートとしては、イソシアナト基を複数有する化合物が用いられ、ジイソシアネートを用いることが好ましい。
ジイソシアネートとしては、例えば、トリレンジイソシアネートおよびその水素添加物、キシリレンジイソシアネートおよびその水素添加物、ジフェニルメタンジイソシアネートおよびその水素添加物、1,5-ナフチレンジイソシアネートおよびその水素添加物、ヘキサメチレンジイソシアネート、トリメチルヘキサメチレンジイソシアネート、テトラメチルキシリレンジイソシアネート、イソホロンジイソシアネート、4,4’-ジシクロヘキシルジイソシアネート、1,3-ビス(イソシアネートメチル)シクロヘキサン、ノルボルナンジイソシアネート等が挙げられる。
また、ポリウレタン(a1)の骨格に含まれるポリイソシアネート由来の構造と、ポリウレタン(a2)の骨格に含まれるポリイソシアネート由来の構造とは、同じであってもよいし、異なっていてもよい。
ポリウレタン(A)に含まれるポリウレタン(a2)の割合は、分子数基準でポリウレタン(A)の0~20%であることが好ましく、0~10%がより好ましく、0%がさらに好ましい。
ポリウレタン(A)に含まれるポリウレタン(a1)の割合が80%以上であると、ポリウレタン(A)を含む粘着剤組成物の硬化物が、十分に凝集力の大きいものとなり、好ましい。
ポリウレタン(A)の質量平均分子量は、ゲル・パーミエーション・クロマトグラフィー(GPC-101;昭和電工株式会社製Shodex(登録商標))(以下、GPCという。)により測定したポリスチレン換算の値である。GPCの測定条件は、以下のとおりである。
カラム:LF-804(昭和電工株式会社製)
カラム温度:40℃
試料:ポリウレタン(A)の0.2質量%テトラヒドロフラン溶液
流量:1ml/分
溶離液:テトラヒドロフラン
検出器:RI検出器(示差屈折率検出器)
(メタ)アクリルモノマー(B)は、(メタ)アクリロイルオキシ基を有する化合物であればよく、特に限定されない。(メタ)アクリルモノマー(B)としては、(メタ)アクリロイルオキシ基を有する化合物を、1種のみを単独で用いてもよいし、2種以上を混合して用いてもよい。(メタ)アクリルモノマー(B)としては、単官能(メタ)アクリレートを用いてもよいし、多官能(メタ)アクリレートを用いてもよいし、単官能(メタ)アクリレートと多官能(メタ)アクリレートの両方を用いてもよい。
また、本発明において、多官能(メタ)アクリレートにおける「多官能」とは、(メタ)アクリロイルオキシ基の数が、2つ以上である(メタ)アクリレートを意味する。
アルキル(メタ)アクリレートとしては、炭素数4~10のアルキル基を有するアルキル(メタ)アクリレートを用いることがより好ましい。具体的には、アルキル(メタ)アクリレートとして、メチル(メタ)アクリレート、エチル(メタ)アクリレート、n-ブチル(メタ)アクリレート、2-エチルヘキシル(メタ)アクリレート等が挙げられる。これらの中でも特に、2-エチルヘキシル(メタ)アクリレートおよび/またはn-ブチル(メタ)アクリレートを用いることが好ましい。
多官能(メタ)アクリレートとしては、具体的には、ポリエチレングリコールジ(メタ)アクリレート、ジエチレングリコールジ(メタ)アクリレート、ネオペンチルグリコールジ(メタ)アクリレート、トリエチレングリコールジ(メタ)アクリレート、トリプロピレングリコールジ(メタ)アクリレート、ヒドロキシピバリン酸エステルネオペンチルグリコールジ(メタ)アクリレート、1,3-ビス(ヒドロキシエチル)-5,5-ジメチルヒダントインジ(メタ)アクリレート、α,ω-ジ(メタ)アクリルビスジエチレングリコールフタレート、トリメチロールプロパントリ(メタ)アクリレート、エチレングリコールジ(メタ)アクリレート、テトラエチレングリコールジ(メタ)アクリレート、1,4-ブタンジオールジ(メタ)アクリレート、1,6-ヘキサンジオールジ(メタ)アクリレート、ジアクリロキシエチルフォスフェート、ペンタエリスリトールテトラ(メタ)アクリレートなどが挙げられる。これらの中でも、多官能(メタ)アクリレートとして、粘着剤組成物の硬化性の観点から、トリメチロールプロパントリ(メタ)アクリレートを用いることが好ましい。
連鎖移動剤(C)は、粘着剤組成物を硬化させた硬化物の貯蔵弾性率、損失正接、ゲル分率を制御する目的で、粘着剤組成物中に含有させる。
連鎖移動剤(C)としては、例えば、多官能チオールを好ましく用いることができる。多官能チオールは、分子内に2個以上のメルカプト基を有する化合物である。
光重合開始剤(D)は、特に限定されるものではないが、光ラジカル重合開始剤が好ましい。光重合開始剤(D)としては、例えば、カルボニル系光重合開始剤、スルフィド系光重合開始剤、アシルホスフィンオキサイド系光重合開始剤、キノン系光重合開始剤、スルホクロリド系光重合開始剤、チオキサントン系光重合開始剤などを用いることができる。これらの光重合開始剤(D)中でも、粘着剤組成物を光硬化させて得られる硬化物の透明性の観点から、アシルホスフィンオキサイド系光重合開始剤を用いることが好ましく、具体的には、2,4,6-トリメチルベンゾイルジフェニルフォスフィンオキサイドを用いることが好ましい。
本実施形態の粘着剤組成物は、ポリウレタン(A)と、(メタ)アクリルモノマー(B)と、連鎖移動剤(C)と、光重合開始剤(D)とを含み、さらに必要に応じて、脂肪酸エステル(E)を含有してもよい。
脂肪酸エステル(E)は、粘着剤組成物の硬化物を粘着剤層として用いた粘着シートにおける粘着力を制御するとともに、粘着剤層のラミネート性(濡れ性)および泡抜け性(被着体に粘着シートを貼り合わせた時に挟み込んだ気泡の抜けやすさ)を向上させる目的で含有させる。
本実施形態の粘着剤組成物は、溶剤を含んでもよいが、溶剤を実質的に含まない無溶剤のものであることがより好ましい。
本実施形態の粘着剤組成物が溶剤を含む場合、例えば、レベリング剤および/または軟化剤として溶剤を用いることができる。
本実施形態の粘着剤組成物は、本発明の効果を損なわない範囲で、必要に応じて、その他の添加剤を含有していてもよい。添加剤としては、例えば、可塑剤、表面潤滑剤、酸化防止剤、老化防止剤、光安定剤、紫外線吸収剤、重合禁止剤、ベンゾトリアゾール系等の光安定剤、リン酸エステル系およびその他の難燃剤、界面活性剤のような帯電防止剤、染料などが挙げられる。
本実施形態の粘着剤組成物は、光硬化性であり、硬化後の厚さが150μmになるように、照射量1000mJ/cm2で硬化させた硬化物のゲル分率が、50~65質量%の範囲内である。照射量1000mJ/cm2で硬化させた硬化物のゲル分率は、ポリウレタン(A)と、(メタ)アクリルモノマー(B)と、連鎖移動剤(C)と、光重合開始剤(D)とを含む本実施形態の粘着剤組成物において、連鎖移動剤(C)および/または光重合開始剤(D)の含有量を制御することにより調整できる。より具体的には、連鎖移動剤(C)および/または光重合開始剤(D)の含有量を増やすとゲル分率が低くなり、連鎖移動剤(C)および/または光重合開始剤(D)の含有量を減らすとゲル分率が高くなる。
本発明において、照射量1000mJ/cm2で粘着剤組成物を硬化させた硬化物のゲル分率は、以下のようにして測定する。
まず、厚さ75μmの剥離PETフィルム(東山フィルム株式会社製、商品名:クリーンセパ(商標)HY-S10-2)上に、アプリケーターを用いて硬化後の厚さが150μmとなるように、粘着剤組成物を塗布する。次いで、粘着剤組成物の塗布面を厚さ75μmのシリコーン系の超軽剥離PETフィルム(東洋紡株式会社製、品名:E7006)で覆う。
ゲル分率(%)=[A/B]×100
A:トルエンに浸漬した後の測定用サンプルの質量(トルエンの質量は含まない)
B:トルエンに浸漬する前の測定用サンプルの質量
本実施形態の粘着剤組成物を、硬化後の厚さが150μmになるように、照射量1000mJ/cm2で硬化させた硬化物は、周波数1Hzで測定した25℃における貯蔵弾性率が1.0×104~1.0×105であり、損失正接が0.25~0.55であることが好ましい。
照射量1000mJ/cm2で硬化させた硬化物を、周波数1Hzで測定した25℃における貯蔵弾性率および損失正接は、粘着剤組成物中に含まれる連鎖移動剤(C)および/または光重合開始剤(D)の含有量を制御することにより調整できる。より具体的には、連鎖移動剤(C)および/または光重合開始剤(D)の含有量を増やすと、貯蔵弾性率が低くなるとともに損失正接が大きくなる。また、連鎖移動剤(C)および/または光重合開始剤(D)の含有量を減らすと、貯蔵弾性率が高くなるとともに損失正接が小さくなる。
本発明において、照射量1000mJ/cm2で粘着剤組成物を硬化させた硬化物の周波数1Hzで測定した25℃における貯蔵弾性率および損失正接は、以下の方法により測定する。
まず、上述したゲル分率の測定方法と同様にして、粘着剤組成物を硬化させて厚さ150μmの硬化物(粘着剤層)を有するシートを作製する。前記硬化物(粘着剤層)を有するシートの粘着剤層から剥離PETフィルムおよび超軽剥離PETフィルムを剥離する。そして、剥離した厚さ150μmの粘着剤層を10枚積層して、厚さ1.5mmの積層シートとする。得られた積層シートから縦8mm、横8mmの正方形シートを切り出し、測定用サンプルとする。
次に、本実施形態の粘着剤組成物の製造方法について、例を挙げて詳細に説明する。
以下、本実施形態の粘着剤組成物に含まれる成分のうち、ポリウレタン(A)については、好ましい合成方法について例を挙げて説明する。本実施形態の粘着剤組成物に含まれる成分のうち、(メタ)アクリルモノマー(B)、連鎖移動剤(C)、光重合開始剤(D)、脂肪酸エステル(E)など、ポリウレタン(A)を除く各成分については、市販品を容易に購入でき、また各成分として用いる化合物の種類によってそれぞれ合成方法が異なるため、合成方法の説明を省略する。
以下、本実施形態の粘着剤組成物に含まれるポリウレタン(A)の好ましい合成方法の一例について説明する。なお、ポリウレタン(A)の合成方法は、以下に示す合成方法に限定されるものではなく、合成に用いる原料および設備などの条件によって、適宜変更可能である。
アルキルアルコールとしては、(メタ)アクリロイル基を有さず、ヒドロキシ基を1個有するものであればよく、直鎖型、分岐型、脂環型のアルキルアルコールなどを用いることができ、特に限定されない。上記アルキルアルコールは、1種のみ単独で使用してもよいし、2種類以上を組み合わせて使用してもよい。
次に、ポリウレタン(A)の好ましい合成方法の他の例について説明する。
以下に示すポリウレタン(A)の合成方法においても上記の合成方法の例と同様に、ヒドロキシ基とイソシアナト基との反応は、いずれの工程においても、イソシアナト基に不活性な有機溶媒の存在下で、ジブチルスズジラウレート、ジブチルスズジエチルヘキソエート、ジオクチルスズジラウレートなどのウレタン化触媒を用いて行う。また、ヒドロキシ基とイソシアナト基との反応は、いずれの工程においても、30~100℃で1~5時間継続して行うことが好ましい。ウレタン化触媒の使用量は、反応物(原料)の総質量に対して、50~500質量ppmであることが好ましい。
具体的には、まず、ポリオキシアルキレンポリオールとポリイソシアネートとを、ヒドロキシ基量(分子数基準、以下同じ)がイソシアナト基量(分子数基準、以下同じ)より多くなる割合で仕込む。その後、ポリオキシアルキレンポリオールとポリイソシアネートとを反応させて、ポリウレタン(A)の前駆体として、末端にヒドロキシ基を有するポリウレタンを合成する。
アルキルイソシアネートとしては、(メタ)アクリロイル基を有さず、イソシアナト基を1個有するものであればよく、直鎖型、分岐型、脂環型のアルキルイソシアネートなどを用いることができ、特に限定されない。上記アルキルイソシアネートは、1種のみ単独で使用してもよいし、2種類以上を組み合わせて使用してもよい。
本実施形態の粘着剤組成物は、上記の合成方法により得られたポリウレタン(A)と、(メタ)アクリルモノマー(B)と、連鎖移動剤(C)と、光重合開始剤(D)と、必要に応じて添加される脂肪酸エステル(E)およびその他の添加剤とを混合する方法により製造できる。
本実施形態の粘着剤組成物に含まれる各成分を混合する方法は、特に限定されるものではなく、例えば、ホモディスパー、パドル翼などの攪拌翼を取り付けた攪拌装置を用いて行うことができる。
次に、本実施形態の粘着シートの製造方法について説明する。
本実施形態の粘着シートの製造方法は、特に限定されるものではなく、公知の方法を用いて製造できる。
例えば、シート状の基材上に、粘着剤組成物を塗布し、セパレーターをラミネートして積層体とする。その後、セパレーターを介して粘着剤組成物に紫外線を照射し、粘着剤組成物を光硬化させる。このことにより、基材上に、粘着剤組成物の硬化物からなる粘着剤層が形成された粘着シートが得られる。
光の照射強度は、粘着剤組成物を充分に硬化させることができ、かつ硬化物のゲル分率が50~65質量%の範囲内となる条件であればよく、例えば、50~3000mW/cm2であることが好ましい。光の照射強度が弱いと硬化に時間がかかり、生産性が低下する。また、光の照射強度は、周波数1Hzで測定した25℃における硬化物の貯蔵弾性率および損失正接の値が所望の範囲となるように調整することがより好ましい。
本実施形態の粘着シートは、表面に凹凸部分を有する被着体に貼付され、その後に剥離される用途に用いることができる。具体的には、半導体ウエハのバンプが形成された面に貼付して、半導体ウエハの表面を保護し、所定の加工工程の後に剥離される粘着シートとして好適に使用できる。
これらの観点から、上記の用途に用いられる粘着シートの剥離強度は、剥離速度が0.3m/min.であって、粘着剤層の厚みが50~200μmである場合、10~300gf/25mmであることが好ましく、15~200gf/25mmであることがより好ましく、20~150gf/25mmであることがさらに好ましい。粘着シートの剥離強度の具体的な測定方法は、実施例において後述する。
温度計、撹拌器、滴下ロート、乾燥管付き冷却管を備えた反応器に、ジフェニルメタンジイソシアネートの水素添加物(デスモジュールW、住化コベストロウレタン製)を0.55kg(2.1mol)と、水酸基価が56mgKOH/gのヒドロキシ基を末端に有するポリプロピレングリコール(アクトコールD-2000;三井化学製、数平均分子量2000)を4.01kg(2.0mol)と、ウレタン化触媒であるジオクチルスズ(ネオスタンU-810、日東化成社製)を0.8gとを仕込んだ。
ジフェニルメタンジイソシアネートの水素添加物に代えて、イソホロンジイソシアネート(デスモジュールI、住化コベストロウレタン製)2.1molを用いたこと以外は、ポリウレタン(A-1)の合成法と同様にして、質量平均分子量66,000のポリウレタン(A-2)を得た。
このようにして得られたポリウレタン(A-1)または(A-2)と、表1または2に示す(メタ)アクリルモノマー(B)と連鎖移動剤(C)と光重合開始剤(D)と脂肪酸エステル(E)とを、表1または2に記載の割合で配合し、25℃でディスパーを用いて混合し、実施例1~実施例5および比較例1~比較例5の粘着剤組成物を得た。
2EHA:2-エチルヘキシルアクリレート(東亜合成株式会社製)
BUA:n-ブチルアクリレート(東亜合成株式会社製)
ACMO:アクリロイルモルホリン(新中村化学工業株式会社製)
IBOA:イソボルニルアクリレート(大阪有機化学工業株式会社製)
TMPTA:トリメチロールプロパントリアクリレート(東亜合成株式会社製)
NR1:1,3,5-トリス(3-メルカプトブチルオキシエチル)-1,3,5-トリアジン-2,4,6(1H,3H,5H)-トリオン(昭和電工株式会社製)
TPO(Omnirad TPO H):2,4,6-トリメチルベンゾイルジフェニルフォスフィンオキサイド(IGM Resins B.V.社製)
エキセパールIPM:ミリスチン酸イソプロピル(花王株式会社製)
エキセパールEH-S:ステアリン酸2-エチルヘキシル(花王株式会社製)
上述の方法により、実施例1~実施例5および比較例1~比較例5の粘着剤組成物を用いて測定用サンプルを作製し、照射量1000mJ/cm2で光硬化させた硬化物のゲル分率を測定した。その結果を表1または2に示す。
上述の方法により、実施例1~実施例5および比較例1~比較例5の粘着剤組成物を用いて測定用サンプルを作製し、照射量1000mJ/cm2で光硬化させた硬化物の周波数1Hzで測定した25℃における貯蔵弾性率および損失正接を測定した。その結果を表1または2に示す。
シート状の基材として、厚さ50μmPETフィルム(東洋紡株式会社製、商品名:エステル(商標)フィルムE5100)を用意した。そして、基材のコロナ処理面上に、アプリケーターを用いて実施例1の粘着剤組成物を、硬化後の厚さが150μmとなるように塗布した。
その後、セパレーターを介して粘着剤組成物に、紫外線照射装置(アイグラフィックス株式会社製、UV照射装置3kW、高圧水銀ランプ)を使用して、照射距離25cm、ランプ移動速度1.0m/分、照射量1000mJ/cm2の条件で紫外線を照射し、粘着剤組成物を光硬化させた。このことにより、基材上に、粘着剤組成物の硬化物である粘着剤層と、セパレーターとが積層された実施例1の粘着シートを得た。
しかし、比較例1および比較例5の粘着剤組成物については、硬化不良により、粘着剤組成物の硬化物からなる粘着剤層を形成できなかった。
<剥離力(剥離強度)>
粘着シートを縦25mm、横150mmの大きさに切り取り、セパレーターを剥がして粘着剤層を露出させた。その後、露出した粘着剤層の全面を、ガラス板にラミネートして、質量2kg(荷重19.6N)のゴムローラー(直径:85mm、幅:50mm)を1往復させることにより、測定用サンプルを得た。得られた測定用サンプルを、温度23℃および相対湿度50%RHの環境下に30分間放置した。その後、JIS K 6854-2に準じて、剥離速度0.3m/min.で180°方向の引張試験を行って、ガラス板に対する剥離強度(gf/25mm)を測定した。その結果を表1または2に示す。
粘着シートを縦25mm、横50mmの大きさに切り取り、セパレーターを剥がして粘着剤層を露出させた。その後、露出した粘着剤層の表面と、バンプ付きウエハ(ウォルツ社製、WALTS-TEG FC150SCJY LF(PI)、バンプ高さ:75μm、バンプサイズ:直径90μm)のバンプとを対向させて設置した。そして、粘着シートの基材上に、質量2kg(荷重19.6N)のゴムローラー(直径:85mm、幅:50mm)を、速度10mm/secで3往復させて、粘着シートとバンプ付きウエハとを貼り合わせた。
「基準」
○(可):粘着シートの粘着剤層とバンプ付きウエハのバンプ周辺との間に空隙がない。
×(不可):粘着シートの粘着剤層とバンプ付きウエハのバンプ周辺との間に空隙がある。
粘着シートを縦25mm、横50mmの大きさに切り取り、セパレーターを剥がして粘着剤層を露出させた。その後、露出した粘着剤層の表面と、バンプ付きウエハ(ウォルツ社製、WALTS-TEG FC150SCJY LF(PI)、バンプ高さ:75μm、バンプサイズ:直径90μm)のバンプと対向させて設置した。そして、粘着シートの基材上に、質量2kg(荷重19.6N)のゴムローラー(直径:85mm、幅:50mm)を、速度10mm/secで3往復させて、粘着シートとバンプ付きウエハとを貼り合わせた。
「基準」
○(可):バンプ周辺に糊残りがない。
×(不可):バンプ周辺に糊残りがある。
また、ゲル分率が65質量%を超える比較例3の粘着シートは、糊残りの評価は「○(良)」であったが、凹凸吸収性の評価が「×(不可)」であった。
Claims (10)
- 少なくともシート状の基材と、前記基材の片面に形成された粘着剤層とを有する粘着シートであって、
前記粘着剤層は、粘着剤組成物の硬化物からなり、ゲル分率が50~65質量%であり、
前記粘着剤組成物は、ポリウレタン(A)と、(メタ)アクリロイルオキシ基を有する化合物からなる(メタ)アクリルモノマー(B)と、連鎖移動剤(C)と、光重合開始剤(D)とを含み、
前記ポリウレタン(A)が、ポリオキシアルキレンポリオール由来の構造およびポリイソシアネート由来の構造を含む骨格を有し、2つ以上の末端に(メタ)アクリロイル基を有するポリウレタン(a1)を含むことを特徴とする粘着シート。 - 前記粘着剤層は、周波数1Hzで測定した25℃における貯蔵弾性率が1.0×104~1.0×105であり、
かつ、周波数1Hzで測定した25℃における損失正接が0.25~0.55である、請求項1に記載の粘着シート。 - 前記粘着剤層の厚みが50~500μmである、請求項1または請求項2に記載の粘着シート。
- ポリウレタン(A)と、(メタ)アクリロイルオキシ基を有する化合物からなる(メタ)アクリルモノマー(B)と、連鎖移動剤(C)と、光重合開始剤(D)とを含み、
前記ポリウレタン(A)が、ポリオキシアルキレンポリオール由来の構造およびポリイソシアネート由来の構造を含む骨格を有し、2つ以上の末端に(メタ)アクリロイル基を有するポリウレタン(a1)を含み、
照射量1000mJ/cm2で光硬化させた硬化物のゲル分率が50~65質量%であることを特徴とする、粘着剤組成物。 - 前記硬化物は、周波数1Hzで測定した25℃における貯蔵弾性率が1.0×104~1.0×105であり、
かつ、周波数1Hzで測定した25℃における損失正接が0.25~0.55である、請求項4に記載の粘着剤組成物。 - 前記(メタ)アクリルモノマー(B)が、単官能(メタ)アクリレートおよび多官能(メタ)アクリレートを含有する、請求項4または請求項5に記載の粘着剤組成物。
- 前記(メタ)アクリルモノマー(B)の合計を100モル%としたときに、前記単官能(メタ)アクリレートを85~99モル%、前記多官能(メタ)アクリレートを1~15モル%含有する、請求項6に記載の粘着剤組成物。
- 前記連鎖移動剤(C)が、多官能チオールである、請求項4~請求項7のいずれか一項に記載の粘着剤組成物。
- 前記ポリウレタン(A)を20~50質量%、
前記(メタ)アクリルモノマー(B)を49~79質量%、
前記連鎖移動剤(C)を0.5~5質量%、
前記光重合開始剤(D)を0.01~5質量%含む、請求項4~請求項8のいずれか一項に記載の粘着剤組成物。 - 更に脂肪酸エステル(E)を含有する、請求項4~請求項9のいずれか一項に記載の粘着剤組成物。
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