Adhesive sheet for semiconductor processing

Abstract

An object of the present invention is to provide an adhesive sheet for semiconductor processing that is also suitable for use modes including high-temperature processes. The solution of the present invention is to provide an adhesive sheet for semiconductor processing including an adhesive layer constituting an adhesive surface. For the above-mentioned adhesive sheet for semiconductor processing, in one mode, the conventional peel force Fd a2 is 0.50 N / 20 mm or less, and the conventional peel force Fd a2 is measured by the following method: attaching the above-mentioned adhesive surface to a silicon wafer, performing a heat treatment at 175 °C for 15 minutes and an ultraviolet irradiation treatment with an accumulated light quantity of 1000 mJ / cm 2 , and then measuring the peel strength under the conditions of a tensile speed of 300 mm / minute and a peel angle of 180 degrees.

Description

Technical Field

[0001] The present invention relates to an adhesive sheet for semiconductor processing. Background Art

[0002] In the manufacturing process of semiconductor elements, in the process of performing processing such as grinding and cutting on a semiconductor wafer on which a circuit is formed, in order to protect and fix the semiconductor wafer, generally, it is performed in a state where an adhesive sheet (adhesive sheet for semiconductor processing) is attached to the circuit formation surface side of the semiconductor wafer (adherend). For example, when grinding the back surface of a semiconductor wafer (backgrind), in order to protect the circuit formation surface (front surface) of the semiconductor wafer and hold (fix) the semiconductor wafer, a backgrind tape is used (for example, Patent Document 1).

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2017-212441 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] For a backgrind tape and other adhesive sheets for semiconductor processing, after achieving their intended use, they are peeled off from the adherend at a desired timing. At this time, from the viewpoint of preventing damage to the adherend, for an adhesive sheet for semiconductor processing, easy peelability from the adherend is required. In order to achieve the easy peelability, it is known to use an ultraviolet (UV) curable adhesive. For an adhesive sheet for semiconductor processing using a UV curable adhesive, by irradiating UV at an appropriate timing before peeling off from the adherend, the peel force is decreased, and thus, damage to the adherend caused by the load during peeling of the adhesive sheet can be suppressed. However, for a conventional adhesive sheet for semiconductor processing using a UV curable adhesive, if it is exposed to a high temperature state of a specified temperature or higher after being attached to the adherend, even if UV is irradiated subsequently, the peel force will be difficult to decrease, and thus, its application in a processing step (high temperature step) exposed to a high temperature is difficult. For example, in peeling after a high temperature step, there may be residual glue on the adherend and damage to the adherend caused by the load during peeling.

[0008] The present invention has been made in view of the above circumstances, and an object thereof is to provide an adhesive sheet for semiconductor processing that is also suitable for a usage mode including a high temperature step.

[0009] Means for Solving the Problems

[0010] The adhesive sheet for semiconductor processing disclosed in this specification includes an adhesive layer that constitutes the adhesive surface. In some embodiments of the above-mentioned adhesive sheet for semiconductor processing (hereinafter, sometimes simply referred to as "adhesive sheet"), the conventional peel force Fd of the adhesive sheet a2 is 0.50 N / 20 mm or less (hereinafter, also referred to as "Condition A"). The conventional peel force Fd a2 is measured by the following method:

[0011] Attach the above-mentioned adhesive surface to a silicon wafer, perform a heat treatment at 175 °C for 15 minutes and a UV irradiation treatment with an accumulated light quantity of 1000 mJ / cm 2 , and then measure the peel strength under the conditions of a tensile speed of 300 mm / minute and a peel angle of 180 degrees.

[0012] By restricting the conventional peel force Fd of the adhesive sheet as described above a2 , thus, even after the adhesive sheet is exposed to high-temperature conditions, peeling can be inhibited while suppressing the load on the adherend.

[0013] In some embodiments of the adhesive sheet for semiconductor processing disclosed in this specification, the water peel force Fw of the adhesive sheet a2 is 0.30 N / 20 mm or less (hereinafter, also referred to as "Condition B"). The water peel force Fw a2 is measured by the following method:

[0014] Attach the above-mentioned adhesive surface to a silicon wafer, perform a heat treatment at 175 °C for 15 minutes and a UV irradiation treatment with an accumulated light quantity of 1000 mJ / cm 2 , then supply water to the peel front of the adhesive sheet peeled from the silicon wafer, and measure the peel strength under the conditions of a tensile speed of 300 mm / minute and a peel angle of 180 degrees.

[0015] By restricting the water peel force Fw of the adhesive sheet as described above a2 , thus, even after the adhesive sheet is exposed to high-temperature conditions, peeling can be inhibited while suppressing the load on the adherend. An adhesive sheet that preferably satisfies both Condition A and Condition B is preferred.

[0016] In some embodiments of the adhesive sheet for semiconductor processing disclosed in this specification, the conventional peel force Fd of the adhesive sheet b2 is 2.00 N / 20 mm or less (hereinafter, also referred to as "Condition C"). The conventional peel force Fd b2 is measured by the following method:

[0017] Attach the above-mentioned adhesive surface to a silicon wafer, perform a heat treatment at 200 °C for 15 minutes and a UV irradiation treatment with an accumulated light quantity of 1000 mJ / cm 2After the UV irradiation treatment, the peel strength was measured under the conditions of a stretching speed of 300 mm / minute and a peeling angle of 180 degrees.

[0018] By restricting the conventional peel force Fd of the adhesive sheet as described above b2 , thus, even after the adhesive sheet is exposed to more severe high-temperature conditions, peeling against the adherend can be suppressed.

[0019] In some embodiments of the adhesive sheet for semiconductor processing disclosed in this specification, the water peel force Fw of the adhesive sheet b2 is 1.00 N / 20 mm or less (hereinafter, also referred to as "Condition D"). The water peel force Fw b2 is measured by the following method:

[0020] The above adhesive surface was attached to a silicon wafer, and after heat treatment at 200 °C for 15 minutes and UV irradiation treatment with an accumulated light amount of 1000 mJ / cm 2 , water was supplied to the peeling front of the adhesive sheet peeled from the silicon wafer, and the peel strength was measured under the conditions of a stretching speed of 300 mm / minute and a peeling angle of 180 degrees.

[0021] By restricting the water peel force Fw of the adhesive sheet as described above b2 , thus, even after the adhesive sheet is exposed to more severe high-temperature conditions, peeling against the adherend can be suppressed. An adhesive sheet that preferably satisfies both Condition C and Condition D is preferred.

[0022] In some embodiments of the adhesive sheet for semiconductor processing disclosed in this specification, for the adhesive sheet, according to the above conventional peel force Fd a2 [N / 20 mm], and in addition to performing the heat treatment at 200 °C for 15 minutes instead of the heat treatment at 175 °C for 15 minutes, and performing the same operation as the above conventional peel force Fd a2 The conventional peel force Fd measured b2 [N / 20 mm], the conventional peel force difference calculated by the following formula Fd b2 -Fd a2 is 1.50 N / 20 mm or less (hereinafter, also referred to as "Condition E"). Thus, for the adhesive sheet, even if temperature unevenness or processing unevenness occurs in a high-temperature process, it is not easily affected by the peel force.

[0023] In some embodiments of the adhesive sheet for semiconductor processing disclosed in this specification, the initial conventional peel force Fd0 of the adhesive sheet is 0.30 N / 20 mm or more (hereinafter, also referred to as "Condition F"). The initial conventional peel force Fd0 is measured by the following method:

[0024] After attaching the above-mentioned adhesive surface to a silicon wafer, the peel strength is measured under the conditions of a pulling speed of 300 mm / minute and a peel angle of 180 degrees.

[0025] Such an adhesive sheet exhibits appropriate adhesiveness as an adhesive sheet for semiconductor processing and can suitably contribute to the improvement of processability.

[0026] In some embodiments of the adhesive sheet for semiconductor processing disclosed in this specification, the non-heated conventional peel force Fd of the adhesive sheet U1 is 0.10 N / 20 mm or less (hereinafter, also referred to as "Condition G"). The non-heated conventional peel force Fd U1 is measured by the following method:

[0027] Attach the above-mentioned adhesive surface to a silicon wafer, perform UV irradiation treatment with an accumulated light amount of 1000 mJ / cm 2 and then measure the peel strength under the conditions of a pulling speed of 300 mm / minute and a peel angle of 180 degrees.

[0028] Such an adhesive sheet can be used, for example, in semiconductor processing that does not include high-temperature processes and can exhibit excellent light peelability during peeling after UV irradiation.

[0029] In some embodiments of the adhesive sheet for semiconductor processing disclosed in this specification, the non-heated water peel force Fw of the adhesive sheet U1 is 0.05 N / 20 mm or less (hereinafter, also referred to as "Condition H"). The non-heated water peel force Fw U1 is measured by the following method:

[0030] Attach the above-mentioned adhesive surface to a silicon wafer, perform UV irradiation treatment with an accumulated light amount of 1000 mJ / cm 2 and then supply water to the peeling front of the adhesive sheet peeled from the silicon wafer, and measure the peel strength under the conditions of a pulling speed of 300 mm / minute and a peel angle of 180 degrees.

[0031] Such an adhesive sheet can be used, for example, in semiconductor processing that does not include high-temperature processes, and can particularly well reduce the load on the adherend by performing peeling using the water peeling method after UV irradiation.

[0032] It should be noted that the scope of the invention claimed in this patent application may also include a solution formed by appropriately combining the above-mentioned various elements. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a cross-sectional view schematically showing a structural example of the adhesive sheet.

[0034] ​Figure 2 is a cross-sectional view schematically showing another structural example of the adhesive sheet.

[0035] Figure 3 is a cross-sectional view schematically showing another structural example of the adhesive sheet.

[0036] Figure 4 is a cross-sectional view schematically showing another structural example of the adhesive sheet.

[0037] Figure 5 is a cross-sectional view schematically showing another structural example of the adhesive sheet.

[0038] Figure 6 is a cross-sectional view schematically showing another structural example of the adhesive sheet.

[0039] Description of Reference Numerals

[0040] 1, 2, 3, 4, 5, 6 Adhesive sheets

[0041] 10 Substrate

[0042] 10A First surface

[0043] 10B Second surface

[0044] 21, 22 Adhesive layers

[0045] 21A First adhesive surface

[0046] 21B Second adhesive surface

[0047] 31, 32 Release liners Detailed Description of the Invention

[0048] Hereinafter, preferred embodiments of the present invention will be described. It should be noted that, regarding matters necessary for the implementation of the present invention other than those specifically described in this specification, those skilled in the art can understand based on the teachings of implementing the invention described in this specification and the common general knowledge in the art at the time of application. The present invention can be implemented based on the content disclosed in this specification and the common general knowledge in the art. In addition, in the following drawings, sometimes the same reference numerals are used to denote components and parts that perform the same function, and sometimes repeated descriptions are omitted or simplified. In addition, for the embodiments described in the drawings, they are schematically shown for clearly explaining the present invention, and do not necessarily correctly represent the dimensions and ratios of the actually provided products.

[0049] In this specification, the method of peeling the adhesive sheet from the adherend using an aqueous release liquid such as water (typically, the method of supplying the aqueous release liquid to the peeling front for peeling from the adherend) is sometimes referred to as "water peeling" or "water peeling method". ​​​​​

[0050] In this specification, the main chain of a polymer refers to the chain-like structure that forms the backbone of the polymer. Additionally, the side chain of a polymer refers to a group (side group, pendant) bonded to the above-mentioned main chain or a molecular chain that can be regarded as a side group.

[0051] In this specification, the so-called "acrylic polymer" refers to a polymer derived from a monomer raw material containing more than 50% by weight (preferably more than 70% by weight, for example, more than 90% by weight) of acrylic monomers. The above-mentioned acrylic monomers refer to monomers having at least one (meth)acryloyl group in one molecule. Additionally, in this specification, the so-called "(meth)acryloyl group" means a meaning including an acryloyl group and a methacryloyl group. Similarly, respectively, the so-called "(meth)acrylate" means a meaning including an acrylate and a methacrylate, and the so-called "(meth)acrylene-" means a meaning including acrylene- and methacrylene-.

[0052] Additionally, in this specification, the so-called "actinic energy ray" refers to a concept including light such as ultraviolet rays, visible light, and infrared rays, and radiation such as α-rays, β-rays, γ-rays, electron beams, neutron beams, and X-rays.

[0053] <Example of the structure of the adhesive sheet>

[0054] The adhesive sheet disclosed in this specification includes an adhesive layer. Typically, this adhesive layer constitutes at least one surface of the adhesive sheet. The adhesive sheet can be an adhesive sheet with a substrate in a form having an adhesive layer on one or both sides of a substrate (support), or can be an adhesive sheet in a form not including a substrate (adhesive sheet without a substrate).

[0055] Here, the concept of the adhesive sheet can include products called adhesive tapes, adhesive labels, adhesive films, etc. Additionally, typically, the above-mentioned adhesive layer can be formed continuously, but is not limited to the above form. For example, it can be an adhesive layer formed in a regular or irregular pattern such as a dot shape or a stripe shape. Additionally, the adhesive sheet provided by this specification can be in a roll shape or a single sheet shape. Or, it can also be an adhesive sheet in a form further processed into various shapes.

[0056] The adhesive sheet disclosed in this specification can be, for example, an adhesive sheet having Figures 1 to 6 the cross-sectional structure schematically shown in Figure 1 , Figure 2 is a structural example of a single-sided adhesive sheet with a substrate (single-sided adhesive sheet with a substrate). Figure 1 The adhesive sheet 1 shown has a structure in which an adhesive layer 21 is provided on one surface 10A (non-peelable) of a substrate 10, and the surface (adhesive surface) 21A of this adhesive layer 21 is protected by a release liner 31 whose at least the adhesive layer side becomes a release surface.Figure 2 The adhesive sheet 2 shown has a structure in which an adhesive layer 21 is provided on one surface 10A (non-peeling surface) of the base material 10. For this adhesive sheet 2, the other surface 10B of the base material 10 becomes the peeling surface. If the adhesive sheet 2 is wound, the adhesive layer 21 abuts against the other surface 10B, and the surface (adhesive surface) 21A of this adhesive layer will be protected by the other surface 10B of the base material 10.

[0057] Figure 3 、 Figure 4 This is a structural example of a double-sided adhesive sheet with a base material (double-sided adhesive sheet with a base material). Figure 3 The adhesive sheet 3 shown has the following structure: Adhesive layers (first adhesive layer) 21 and adhesive layers (second adhesive layer) 22 are respectively provided on the first surface 10A and the second surface 10B (both non-peeling surfaces) of the base material 10. The surface (first adhesive surface) of the first adhesive layer 21 and the surface (second adhesive surface) of the second adhesive layer 22 are respectively protected by peeling liners 31 and 32 whose at least the adhesive layer side becomes the peeling surface. Figure 4 The adhesive sheet 4 shown has the following structure: A first adhesive layer 21 and a second adhesive layer 22 are respectively provided on the first surface 10A and the second surface 10B (both non-peeling surfaces) of the base material 10. The surface (first adhesive surface) of the first adhesive layer 21 among them is protected by a peeling liner 31 whose both sides become the peeling surface. For the adhesive sheet 4, by winding this adhesive sheet 4, the surface (second adhesive surface) of the second adhesive layer 22 abuts against the back surface of the peeling liner 31, and thus, a structure in which the second adhesive surface is also protected by the peeling liner 31 can be formed.

[0058] Figure 5 、 Figure 6 This is a structural example of a double-sided adhesive sheet without a base material (double-sided adhesive sheet without a base material). Figure 5 The adhesive sheet 5 shown has a structure in which one surface (first adhesive surface) 21A and the other surface (second adhesive surface) 21B of the base material-free adhesive layer 21 are respectively protected by peeling liners 31 and 32 whose at least the adhesive layer side becomes the peeling surface. Figure 6 The adhesive sheet 6 shown has a structure in which one surface (first adhesive surface) 21A of the adhesive layer 21 is protected by a peeling liner 31 whose both sides become the peeling surface. If it is wound, the other surface (second adhesive surface) 21B of the adhesive layer 21 abuts against the back surface of the peeling liner 31, and thus, a structure in which the other surface 21B is also protected by the peeling liner 31 can be formed.

[0059] For a double-sided adhesive sheet without a base material or with a base material, by attaching a non-peeling base material to one adhesive surface, it can be used as a single-sided adhesive sheet with a base material.

[0060] Before use (before attaching to the adherend), the adhesive sheet can be, for example, in the form of an adhesive sheet with a release liner, where the adhesive surface is protected by the release liner as shown in Figures 1 to 6 . As the release liner, there is no particular limitation. For example, a release liner obtained by subjecting the surface of a liner substrate such as a resin film or paper to a release treatment, a release liner formed of a low-adhesion material such as a fluorine-based polymer (e.g., polytetrafluoroethylene) or a polyolefin-based resin (e.g., polyethylene, polypropylene), etc. can be used. In the above release treatment, for example, a release treatment agent such as a silicone-based or long-chain alkyl-based release treatment agent can be used. In some embodiments, a resin film subjected to a release treatment is preferably used as the release liner.

[0061] When the adhesive sheet disclosed in this specification is in the form of a double-sided adhesive sheet with a substrate or a double-sided adhesive sheet without a substrate, the adhesive (first adhesive) constituting the first adhesive surface and the adhesive (second adhesive) constituting the second adhesive surface can have the same composition or different compositions. A double-sided adhesive sheet without a substrate with different compositions of the first and second adhesive surfaces can be realized, for example, by an adhesive layer having a multilayer structure formed by directly laminating two or more kinds of adhesive layers with different compositions (without a substrate in between).

[0062] The adhesive sheet disclosed in this specification preferably has an adhesive surface constituted by an adhesive layer having active energy ray curability (active energy ray curable adhesive layer). In the case of a double-sided adhesive sheet having a first adhesive surface and a second adhesive surface, it is preferred that at least one of the adhesive surfaces is an adhesive surface constituted by an active energy ray curable adhesive layer. The other adhesive surface can be an adhesive surface constituted by an active energy ray curable adhesive layer or an adhesive layer not having active energy ray curability (non-active energy ray curable adhesive layer). The adhesive sheet disclosed in this specification can be preferably implemented in the form of a single-sided adhesive sheet with a substrate having an adhesive surface constituted by an active energy ray curable adhesive layer. The above active energy ray curable adhesive layer preferably contains compound A described later.

[0063] <Adhesive layer>

[0064] The adhesive layer (preferably a UV curable adhesive layer) constituting the adhesive surface of the adhesive sheet disclosed in this specification can be an adhesive layer composed of one or more kinds of adhesives selected from known various adhesives such as acrylic adhesives, rubber adhesives (natural rubber-based, synthetic rubber-based, their mixed systems, etc.), silicone adhesives, polyester adhesives, urethane adhesives, polyether adhesives, polyamide adhesives, fluorine adhesives, etc. Here, an acrylic adhesive means an adhesive based on an acrylic polymer. The same applies to other adhesives such as rubber adhesives.

[0065] Note that in this specification, the "base polymer" of the adhesive refers to the main component of the polymer contained in the adhesive. In addition, in this specification, the "main component" refers to the component contained in an amount exceeding 50% by weight, unless otherwise specified.

[0066] (Acrylic adhesive layer)

[0067] In some embodiments of the adhesive sheet disclosed in this specification, the above-mentioned adhesive layer may be an acrylic adhesive layer containing an acrylic adhesive as the main component. In the adhesive sheet having an acrylic adhesive layer, it is possible to suitably achieve both adhesive properties suitable for semiconductor processing and easy peelability based on water peeling. The acrylic adhesive layer is also preferred from the viewpoint of easily imparting the curability of active energy rays described later.

[0068] As the acrylic adhesive, for example, a polymer containing a monomer raw material containing (meth)acrylic acid alkyl ester or a modified product obtained by chemically modifying the like, such as an acrylic polymer, is preferably used as the base polymer. As the constituent components of the above-mentioned monomer raw material, (meth)acrylic acid alkyl esters having a linear or branched alkyl group having 1 to 20 carbon atoms at the ester terminal can be preferably used. Hereinafter, (meth)acrylic acid alkyl esters having an alkyl group having X or more and Y or less carbon atoms at the ester terminal may sometimes be represented as "(meth)acrylic acid C X-Y alkyl ester". From the viewpoint of easily obtaining adhesive properties suitable for semiconductor processing applications, as (meth)acrylic acid C 1-20 alkyl ester, (meth)acrylic acid C 1-14 (e.g., C 1-12 ) alkyl ester is preferred. In addition, as acrylic acid C 1-20 alkyl ester, acrylic acid C 1-20 (e.g., C 1-14 , typically C 1-12 ) alkyl ester is preferred.

[0069] As (meth)acrylic acid C 1-20Non-limiting specific examples of the alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate, etc. These (meth)acrylic acid alkyl esters can be used alone or in combination of two or more. Preferred (meth)acrylic acid alkyl esters include ethyl acrylate (EA), n-butyl acrylate (BA), 2-ethylhexyl acrylate (2EHA), and lauryl acrylate (LA). In some embodiments, the monomer raw material contains at least one of EA, BA, 2EHA, and LA, preferably contains at least one of EA, BA, and 2EHA, and more preferably contains at least one of BA and 2EHA.

[0070] From the perspective of easily achieving a balance of properties, in some embodiments, the (meth)acrylic acid C 1-20 alkyl ester usually preferably accounts for 40% by weight or more, more preferably more than 50% by weight in the above monomer raw material. For example, it can be 55% by weight or more, 60% by weight or more, 65% by weight or more, 70% by weight or more. For the same reason, the proportion of the (meth)acrylic acid C 1-20 alkyl ester in the above monomer raw material is usually preferably 99.9% by weight or less, can be 99% by weight or less, 98% by weight or less. From the perspective of easily forming an adhesive sheet suitable for light peeling by supplying an aqueous peeling liquid to the peeling front peeled from the adherend, in some embodiments, the proportion of the (meth)acrylic acid C 1-20 alkyl ester in the above monomer raw material can be, for example, 95% by weight or less, 85% by weight or less, less than 80% by weight, 70% by weight or less, 65% by weight or less.

[0071] In some preferred embodiments, the above (meth)acrylic acid alkyl ester contains a (meth)acrylic acid alkyl ester A1 having an alkyl group with 9 or fewer carbon atoms at the ester terminal (i.e., (meth)acrylic acid C 1-9Alkyl esters). The (meth)acrylic acid alkyl ester A1 can be used alone or in combination of two or more. By having a structure that limits the length of the side-chain alkyl group as described above, there is a tendency to obtain high cohesion (which can highly prevent residual glue). For example, in a structure having a carbon-carbon double bond in the side chain (typically, the end of the side chain) of the polymer, the length of the side-chain alkyl group is limited, and thus, during the curing treatment, the reaction of the carbon-carbon double bond can proceed smoothly. In addition, since the length of the side-chain alkyl group is limited, for an adhesive sheet having an adhesive layer containing a polymer obtained from this monomer, it can be efficiently peeled from the adherend by a peeling method of supplying an aqueous peeling liquid such as water to the peeling front peeled from the adherend.

[0072] The proportion of the (meth)acrylic acid alkyl ester A1 in the whole of the above monomer raw materials is preferably about 30% by weight or more, more preferably about 40% by weight or more, and still more preferably about 55% by weight or more, from the viewpoint of better presenting the function of the (meth)acrylic acid alkyl ester A1. In some embodiments, the proportion of the above (meth)acrylic acid alkyl ester A1 can be, for example, about 65% by weight or more, can be about 75% by weight or more, can be about 80% by weight or more. In some other embodiments, the proportion of the above (meth)acrylic acid alkyl ester A1 can be, for example, about 85% by weight or more, can be about 90% by weight or more, can be about 95% by weight or more. The upper limit of the proportion of the (meth)acrylic acid alkyl ester A1 in the above monomer raw materials is not particularly limited, and generally, it is preferably 99.5% by weight or less, and can be, for example, 99% by weight or less. In some embodiments, for example, from the viewpoint of well presenting the function of the above carbon-carbon double bond in an adhesive layer containing a polymer having a carbon-carbon double bond, the proportion of the (meth)acrylic acid alkyl ester A1 in the whole of the above monomer raw materials is preferably about 95% by weight or less, more preferably about 90% by weight or less, can be about 85% by weight or less, can be about 75% by weight or less, can be about 70% by weight or less.

[0073] The proportion of the (meth)acrylic acid alkyl ester A1 in the whole of the (meth)acrylic acid alkyl esters is preferably about 50% by weight or more, more preferably about 70% by weight or more, still more preferably about 80% by weight or more, can be about 90% by weight or more, can be about 95% by weight or more, can be about 99% by weight or more, from the viewpoint of well presenting the function of the (meth)acrylic acid alkyl ester A1. The upper limit of the proportion of the (meth)acrylic acid alkyl ester A1 in the whole of the (meth)acrylic acid alkyl esters is 100% by weight.

[0074] In some embodiments, the above-mentioned (meth)acrylic acid alkyl ester A1 may contain one or more (meth)acrylic acid alkyl esters A3 having an alkyl group with less than 7 carbon atoms at the ester terminal. For an adhesive containing a polymer obtained from a monomer raw material containing (meth)acrylic acid alkyl ester A3, it is easy to provide an adhesive sheet that can be efficiently peeled by a peeling method in which a peeling liquid such as water is supplied to the peeling front peeled from the adherend. In addition, for a radiation curable adhesive containing a polymer obtained from a monomer raw material containing (meth)acrylic acid alkyl ester A3, the curing reaction based on the irradiation of radiation can proceed well. From such a viewpoint, the number of carbon atoms of the alkyl group in (meth)acrylic acid alkyl ester A3 is preferably 6 or less, more preferably 4 or less, and may be 3 or less or 2 or less. In addition, the number of carbon atoms of the alkyl group in (meth)acrylic acid alkyl ester A3 may be 1 or more, and from the viewpoint of adhesion to the adherend, it is preferably 2 or more.

[0075] In the embodiment where the above-mentioned monomer raw material contains (meth)acrylic acid alkyl ester A3, the proportion of (meth)acrylic acid alkyl ester A3 in the whole monomer raw material may be, for example, about 1% by weight or more, usually, preferably about 5% by weight or more, and from the viewpoint of well presenting the function of (meth)acrylic acid alkyl ester A3, it is preferably about 20% by weight or more, more preferably about 30% by weight or more, further preferably about 40% by weight or more, particularly preferably about 50% by weight or more, and may be 60% by weight or more, may be about 70% by weight or more, may be about 80% by weight or more, may be about 90% by weight or more. The upper limit of the proportion of (meth)acrylic acid alkyl ester A3 in the whole monomer raw material is not particularly limited, usually, preferably about 99% by weight or less, and may be 90% by weight or less, for example. In some embodiments, for example, from the viewpoint of well presenting the function of the carbon-carbon double bond in the adhesive layer containing a polymer having a carbon-carbon double bond, the proportion of (meth)acrylic acid alkyl ester A3 in the whole monomer raw material is preferably about 80% by weight or less, more preferably about 70% by weight or less, and further preferably about 60% by weight or less. The above embodiments may be, for example, a method of introducing a reactive group for curing treatment and a functional group serving as a crosslinking point into the polymer.

[0076] The proportion of the alkyl (meth)acrylate A3 in the total alkyl (meth)acrylates is preferably about 5% by weight or more, more preferably about 20% by weight or more, still more preferably about 35% by weight or more, further preferably about 45% by weight or more, particularly preferably about 55% by weight or more. For example, it can be about 65% by weight or more, about 75% by weight or more, about 85% by weight or more, or about 90% by weight or more. The upper limit of the proportion of the alkyl (meth)acrylate A3 in the total alkyl (meth)acrylates is 100% by weight, for example, it can be about 98% by weight or less. In some embodiments, for example, when using the following alkyl (meth)acrylate A2 in combination with the alkyl (meth)acrylate A3, from the perspective of better exhibiting its function, the proportion of the alkyl (meth)acrylate A3 in the total alkyl (meth)acrylates can be, for example, about 90% by weight or less, about 85% by weight or less, about 75% by weight or less, about 60% by weight or less, about 45% by weight or less, about 30% by weight or less, or about 15% by weight or less. The alkyl (meth)acrylate A3 may not be used.

[0077] In some embodiments, the above alkyl (meth)acrylate may contain an alkyl (meth)acrylate A2 having an alkyl group with 7 or more carbon atoms at the ester terminal as the above alkyl (meth)acrylate A1, or as a monomer different from the alkyl (meth)acrylate A1. When using the alkyl (meth)acrylate A2, for example, it may be advantageous from the perspective of adhesion to the adherend. The number of carbon atoms of the alkyl group in the alkyl (meth)acrylate A2 is preferably 8 or more, and can be 9 or more. In addition, from the perspective of adhesion properties such as adhesive strength, the number of carbon atoms of the alkyl group in the alkyl (meth)acrylate A2 is preferably 14 or less, more preferably 12 or less, still more preferably 10 or less, for example, 9 or less, and can be less than 9.

[0078] In the case where the above monomer raw material contains the (meth)acrylic acid alkyl ester A2, the proportion of the (meth)acrylic acid alkyl ester A2 in the whole of the monomer raw material may be, for example, about 1% by weight or more, usually preferably about 5% by weight or more, and from the viewpoint of better exhibiting the function of the (meth)acrylic acid alkyl ester A2, it is preferably about 20% by weight or more, more preferably about 30% by weight or more, further preferably about 40% by weight or more, particularly preferably about 50% by weight or more, and may be, for example, 60% by weight or more, may be about 70% by weight or more, may be about 80% by weight or more, may be about 90% by weight or more. There is no particular limitation on the upper limit of the proportion of the (meth)acrylic acid alkyl ester A2 in the whole of the above monomer raw material, and usually, it is preferably about 99.5% by weight or less, and may be, for example, about 99% by weight or less. In some embodiments, for example, from the viewpoint of better exhibiting the function of the carbon-carbon double bond in the adhesive layer containing a polymer having a carbon-carbon double bond, the proportion of the above (meth)acrylic acid alkyl ester A2 in the whole of the monomer raw material is preferably about 95% by weight or less, may be about 90% by weight or less, may be about 85% by weight or less, may be about 75% by weight or less, may be about 70% by weight or less.

[0079] The proportion of the (meth)acrylic acid alkyl ester A2 in the whole of the (meth)acrylic acid alkyl esters contained in the above monomer raw material is preferably about 5% by weight or more, and from the viewpoint of better exhibiting the function of the (meth)acrylic acid alkyl ester A2, it is preferably about 20% by weight or more, more preferably about 35% by weight or more, further preferably about 45% by weight or more, and may be, for example, about 55% by weight or more, may be about 65% by weight or more, may be about 75% by weight or more, may be about 85% by weight or more, may be about 90% by weight or more, may be about 95% by weight or more. The upper limit of the proportion of the (meth)acrylic acid alkyl ester A2 in the whole of the above (meth)acrylic acid alkyl esters is 100% by weight. In some embodiments, for example, in the case of using the (meth)acrylic acid alkyl ester A3 in combination with the (meth)acrylic acid alkyl ester A2, from the viewpoint of better exhibiting its function, the proportion of the (meth)acrylic acid alkyl ester A2 in the whole of the above (meth)acrylic acid alkyl esters may be, for example, about 95% by weight or less, may be about 90% by weight or less, may be about 80% by weight or less, may be about 70% by weight or less, may be about 60% by weight or less, may be about 45% by weight or less, may be about 30% by weight or less, may be about 20% by weight or less, may be about 10% by weight or less, may be about 5% by weight or less. The (meth)acrylic acid alkyl ester A2 may not be used.

[0080] The monomer raw materials that can be used in the synthesis of acrylic polymers may further contain comonomers copolymerizable with the above-mentioned (meth)acrylic acid alkyl esters. The comonomers can help introduce crosslinking points into the acrylic polymer or improve the cohesion of the acrylic polymer. In addition, for example, for the monomer raw materials that can be used in the synthesis of polymers having carbon-carbon double bonds, it is preferable to use monomers having a functional group (hereinafter also referred to as "functional group A") that can react with the functional group (hereinafter also referred to as "functional group B") of the monomers having carbon-carbon double bonds described later as comonomers.

[0081] As the comonomer, one kind can be used alone or two or more kinds can be used in combination, such as the following functional group-containing monomers.

[0082] Monomers containing a hydroxyl group: for example, (meth)acrylic acid 2-hydroxyethyl ester, (meth)acrylic acid 2-hydroxypropyl ester, (meth)acrylic acid 3-hydroxypropyl ester, (meth)acrylic acid 4-hydroxybutyl ester, (meth)acrylic acid (4-hydroxymethylcyclohexyl)methyl ester and other (meth)acrylic acid hydroxyalkyl esters; unsaturated alcohols such as vinyl alcohol and allyl alcohol; ether compounds such as 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether.

[0083] Monomers containing a carboxyl group: for example, acrylic acid (AA), methacrylic acid (MAA), crotonic acid, isocrotonic acid and other ethylenically unsaturated monocarboxylic acids; ethylenically unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, and citraconic acid.

[0084] Monomers containing an acid anhydride group: for example, maleic anhydride and itaconic anhydride.

[0085] Monomers having a ring containing a nitrogen atom: for example, N-vinyl-2-pyrrolidone, methyl-N-vinylpyrrolidone, vinylpyridine, vinylpyrazine, vinylpyrimidine, N-vinylpiperidone, N-vinylpiperazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-vinylmorpholine, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5-morpholinedione, N-vinylpyrazole, N-vinylisoxazole, N-vinylthiazole, N-vinylisothiazole, N-(meth)acryloylmorpholine, N-(meth)acryloyl-2-pyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, etc.

[0086] Monomers containing an amide group: for example, (meth)acrylamide; N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, N,N-di(n-butyl)(meth)acrylamide, N,N-di(tert-butyl)(meth)acrylamide and other N,N-dialkyl(meth)acrylamides; N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-butyl(meth)acrylamide, N-n-butyl(meth)acrylamide and other N-alkyl(meth)acrylamides; N-vinylcarboxylic acid amides such as N-vinylacetamide; monomers having a hydroxyl group and an amide group, for example, N-(2-hydroxyethyl)(meth)acrylamide, N-(2-hydroxypropyl)(meth)acrylamide, N-(1-hydroxypropyl)(meth)acrylamide, N-(3-hydroxypropyl)(meth)acrylamide, N-(2-hydroxybutyl)(meth)acrylamide, N-(3-hydroxybutyl)(meth)acrylamide, N-(4-hydroxybutyl)(meth)acrylamide and other N-hydroxyalkyl(meth)acrylamides; monomers having an alkoxy group and an amide group, for example, N-methoxymethyl(meth)acrylamide, N-methoxyethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide and other N-alkoxymethyl(meth)acrylamides; N,N-dimethylaminopropyl(meth)acrylamide and other N,N-dialkylaminopropyl(meth)acrylamides, etc.

[0087] Monomers containing an amino group: for example, aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, tert-butylaminoethyl (meth)acrylate.

[0088] Monomers having a succinimide skeleton: for example, N-(meth)acryloyloxymethylene succinimide, N-(meth)acryloyl-6-oxohexamethylene succinimide, N-(meth)acryloyl-8-oxohexamethylene succinimide, etc.

[0089] Maleimides: for example, N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide, etc.

[0090] Itaconimides: for example, N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-laurylitaconimide, etc.

[0091] Monomers containing an epoxy group: for example, glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, allyl glycidyl ether.

[0092] Monomers containing a cyano group: for example, acrylonitrile, methacrylonitrile.

[0093] Monomers containing a keto group: for example, diacetone (meth)acrylamide, diacetone (meth)acrylate, vinyl methyl ketone, vinyl ethyl ketone, allyl acetoacetate, vinyl acetoacetate.

[0094] Monomers containing an alkoxysilyl group: for example, (meth)acrylate containing an alkoxysilyl group such as 3-(meth)acryloyloxypropyltrimethoxysilane, 3-(meth)acryloyloxypropyltriethoxysilane, 3-(meth)acryloyloxypropylmethyldimethoxysilane, 3-(meth)acryloyloxypropylmethyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane and other vinyl compounds containing an alkoxysilyl group.

[0095] Monomers containing an amino group: for example, aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, tert-butylaminoethyl (meth)acrylate.

[0096] Monomers having an epoxy group: for example, glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, allyl glycidyl ether.

[0097] Monomers containing a sulfonic acid group or a phosphoric acid group: for example, styrenesulfonic acid, allylsulfonic acid, sodium vinylsulfonate, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, (meth)acryloylsulfopropyl ester, (meth)acryloyloxynaphthalenesulfonic acid, 2-hydroxyethyl acryloyl phosphate, etc.

[0098] Monomers containing an isocyanate group: for example, 2-isocyanatoethyl (meth)acrylate, (meth)acryloyl isocyanate, m-isopropenyl-α,α-dimethylbenzyl isocyanate.

[0099] The amount of the above-mentioned monomers containing a functional group may be appropriately selected in a manner that can achieve the desired cohesion, and there is no particular limitation. Generally, from the viewpoint of achieving cohesion and other properties (such as adhesiveness) well in a well-balanced manner, the amount of the monomers containing a functional group (in the case of using two or more monomers containing a functional group, it is the total amount thereof) is preferably 0.1% by weight or more, more preferably 0.3% by weight or more, for example, 1% by weight or more of the total monomer raw materials. In addition, the amount of the monomers containing a functional group may be, for example, 50% by weight or less, preferably 40% by weight or less, for example, 35% by weight or less, may be 30% by weight or less, may be 25% by weight or less, may be 20% by weight or less of the total monomer raw materials.

[0100] In some embodiments, the above monomer raw materials may include a hydroxyl group-containing monomer as the functional group-containing monomer. When using a hydroxyl group-containing monomer, the amount used is not particularly limited. For example, it may be 0.01% by weight or more, 0.1% by weight or more, 0.5% by weight or more, 1% by weight or more, 5% by weight or more, or 10% by weight or more of the total monomer raw materials. In some embodiments, the amount of the hydroxyl group-containing monomer used may be, for example, 50% by weight or less of the total monomer raw materials. From the viewpoint of suppressing water absorption of the adhesive, it is generally preferably 40% by weight or less, may be 30% by weight or less, 25% by weight or less, or 20% by weight or less. In addition, in some embodiments, the amount of the hydroxyl group-containing monomer used may be 15% by weight or less, 10% by weight or less, or 5% by weight or less of the total monomer raw materials. Alternatively, the hydroxyl group-containing monomer may not be used.

[0101] In some embodiments, the above monomer raw materials may include a carboxyl group-containing monomer as the functional group-containing monomer. The proportion of the carboxyl group-containing monomer in the total monomer raw materials that can be used in the synthesis of the acrylic polymer may be, for example, 15% by weight or less, 10% by weight or less. From the viewpoints of suppressing water absorption of the adhesive layer during semiconductor processing, etc., it is preferably 7% by weight or less, may be 5% by weight or less, 3% by weight or less, 2% by weight or less, 1% by weight or less, 0.5% by weight or less, or less than 0.1% by weight. The above monomer raw materials may substantially not contain a carboxyl group-containing monomer. Here, the so-called substantially not containing a carboxyl group-containing monomer means that at least the carboxyl group-containing monomer is not intentionally used. For example, the following configuration may be preferably adopted: in the monomer raw materials that can be used in the preparation of a polymer having a carbon-carbon double bond in the side chain, the proportion of the carboxyl monomer is limited as described above.

[0102] In some embodiments, the above monomer raw materials may include a nitrogen atom-containing monomer as the functional group-containing monomer. By using a nitrogen atom-containing monomer, an appropriate polarity can be imparted to the adhesive. This can be advantageous for realizing a lightly peelable adhesive sheet suitable for the supply of an aqueous release liquid such as water. As a preferred example of the nitrogen atom-containing monomer, a monomer having a nitrogen atom-containing ring can be cited. As the monomer having a nitrogen atom-containing ring, from the viewpoints of compatibility, etc., N-vinyl type compounds (such as N-vinyl cyclic amides) such as N-vinyl-2-pyrrolidone, and N-(meth)acryloyl type compounds such as N-(meth)acryloylmorpholine can be preferably adopted.

[0103] When using a monomer having a nitrogen atom (for example, a monomer having a ring containing a nitrogen atom), the amount used is not particularly limited. For example, it can be 1% by weight or more of the total monomer raw materials, can be 2% by weight or more, can be 3% by weight or more, can be 5% by weight or more, can be 7% by weight or more. From the viewpoint of obtaining higher effects, in some embodiments, the amount of the monomer having a nitrogen atom can be 10% by weight or more of the total monomer raw materials, can be 15% by weight or more, can be 20% by weight or more. In addition, from the viewpoint of easily achieving a balance of properties, the amount of the monomer having a nitrogen atom is generally preferably, for example, 40% by weight or less of the total monomer raw materials, can be 35% by weight or less, can be 30% by weight or less, can be 25% by weight or less. In some embodiments, the amount of the monomer having a nitrogen atom can be, for example, 20% by weight or less of the total monomer raw materials, can be 15% by weight or less, can be 10% by weight or less, can be 5% by weight or less. Alternatively, the monomer having a nitrogen atom may not be used.

[0104] When the above monomer raw materials are used in the preparation of a polymer having a carbon-carbon double bond, as a comonomer, a functional group-containing monomer having a functional group (functional group A) capable of reacting with a functional group (functional group B) of a compound having a carbon-carbon double bond described below is preferably used. In the above case, the type of the functional group-containing monomer can be determined according to the above compound type. As the comonomer having functional group A, for example, a monomer containing a hydroxyl group, a monomer containing a carboxyl group, a monomer containing an epoxy group, a monomer containing an isocyanate group are preferably used, and a monomer containing a hydroxyl group is particularly preferred. By using a monomer containing a hydroxyl group as a comonomer, the acrylic polymer has a hydroxyl group. In contrast, by using a monomer containing an isocyanate group as the compound having a carbon-carbon double bond, the hydroxyl group (functional group A) of the above acrylic polymer reacts with the isocyanate group (functional group B) of the above compound, and the carbon-carbon double bond derived from the above compound can be introduced into the acrylic polymer.

[0105] In addition, when using a comonomer for the purpose of reacting with a compound having a carbon-carbon double bond, from the viewpoint of easily obtaining an adhesive layer suitable for water peeling, the amount of the above comonomer (preferably a monomer containing a hydroxyl group) is preferably about 1% by weight or more in all monomer raw materials, more preferably about 5% by weight or more, still more preferably about 10% by weight or more, further preferably about 12% by weight or more, for example, about 14% by weight or more. In addition, from the viewpoint of maintaining good adhesive properties such as adhesiveness, the amount of the above comonomer is preferably about 40% by weight or less in all monomer raw materials, more preferably about 30% by weight or less, still more preferably about 20% by weight or less, and can be, for example, about 15% by weight or less.

[0106] For the monomer raw materials that can be used in the preparation of acrylic polymers, for the purpose of improving the cohesion of the acrylic polymers, etc., comonomers other than the above-mentioned monomers containing functional groups (hereinafter, also referred to as copolymerizable monomers) may also be included.

[0107] As non-limiting specific examples of the above copolymerizable monomers, the following examples can be cited.

[0108] Monomers containing alkoxy groups: For example, alkoxyalkyl (meth)acrylates ((meth)acrylic acid alkoxyalkyl esters) such as 2-methoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, etc.; alkoxy(poly)alkylene glycol (meth)acrylates such as methoxyethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, etc.

[0109] Vinyl esters: For example, vinyl acetate, vinyl propionate, etc.

[0110] Vinyl ethers: For example, vinyl alkyl ethers such as methyl vinyl ether, ethyl vinyl ether, etc.

[0111] Aromatic vinyl compounds: For example, styrene, α-methylstyrene, vinyltoluene, etc.

[0112] Olefins: For example, ethylene, butadiene, isoprene, isobutene, etc.

[0113] (Meth)acrylates having an alicyclic hydrocarbon group: For example, (meth)acrylates containing an alicyclic hydrocarbon group such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, adamantyl (meth)acrylate, etc.

[0114]

[0115] And (meth)acrylates containing a heterocyclic ring such as tetrahydrofurfuryl (meth)acrylate, monomers containing a halogen atom such as vinyl chloride, monomers containing a fluorine atom (meth)acrylate, monomers containing an organosiloxane chain such as polysiloxane (meth)acrylate, (meth)acrylates obtained from terpene compound derivative alcohols, etc.

[0116] Such comonomers may be used singly or in combination of two or more. The amount of the other comonomers described above is not particularly limited and may be appropriately selected according to the purpose and use. For example, it is preferably 20% by weight or less (e.g., 2 to 20% by weight, typically 3 to 10% by weight) of all monomer raw materials of the acrylic polymer.

[0117] In a preferred embodiment, for the above monomer raw materials, from the viewpoint of suppressing gelation, the total proportion of alkoxyalkyl (meth)acrylate and alkoxypolyalkylene glycol (meth)acrylate is preferably limited to less than 20% by weight. The total proportion of the alkoxyalkyl (meth)acrylate and alkoxypolyalkylene glycol (meth)acrylate is more preferably less than 10% by weight, still more preferably less than 3% by weight, and particularly preferably less than 1% by weight. In one embodiment, the above monomer raw materials substantially do not contain alkoxyalkyl (meth)acrylate and alkoxypolyalkylene glycol (meth)acrylate (content is 0 to 0.3% by weight).

[0118] Similarly, in one embodiment, the above monomer raw materials may contain monomers containing alkoxy in a proportion of less than 20% by weight, or may not contain monomers containing alkoxy. The amount of the monomers containing alkoxy in the above monomer raw materials is preferably less than 10% by weight, more preferably less than 3% by weight, still more preferably less than 1% by weight. In a particularly preferred embodiment, the above monomer raw materials substantially do not contain monomers containing alkoxy (content is 0 to 0.3% by weight).

[0119] The method for polymerizing monomer raw materials is not particularly limited, and various polymerization methods known as synthesis methods for acrylic polymers, such as solution polymerization method, emulsion polymerization method, bulk polymerization method, suspension polymerization method, etc., can be appropriately adopted. For example, the solution polymerization method can be preferably adopted. As the monomer supply method during solution polymerization, a one-time charging method of supplying all monomer raw materials together, a continuous supply (dropwise addition) method, a batch supply (dropwise addition) method, etc. can be appropriately adopted. The solvent (polymerization solvent) used in solution polymerization can be appropriately selected from existing known organic solvents. For example, an aromatic compound such as toluene (typically, aromatic hydrocarbons); esters such as ethyl acetate and butyl acetate; aliphatic or alicyclic hydrocarbons such as hexane and cyclohexane; halogenated alkanes such as 1,2-dichloroethane; lower alcohols such as isopropyl alcohol (for example, monohydric alcohols having 1 to 4 carbon atoms); ethers such as tert-butyl methyl ether; ketones such as methyl ethyl ketone; etc. can be used, and any one solvent or a mixed solvent of two or more can be used. The polymerization temperature can be appropriately selected according to the types of monomers and solvents used, the type of polymerization initiator, etc., and can be, for example, about 20°C to 120°C (typically, 40°C to 80°C). Through solution polymerization, a polymerization reaction solution in a form in which the polymer of the monomer raw material is dissolved in the polymerization solvent can be obtained. The adhesive composition for forming the adhesive layer can preferably be manufactured using the above polymerization reaction solution. The method for manufacturing the adhesive composition using the above polymerization reaction solution can include, for example, a step of performing chemical modification such as introducing a carbon-carbon double bond to the polymer contained in the above polymerization reaction solution.

[0120] During polymerization, known or conventional thermal polymerization initiators and photoinitiators can be used according to the polymerization method, polymerization mode, etc. As examples of thermal polymerization initiators, azo-based polymerization initiators, peroxide-based initiators, redox-based initiators based on the combination of peroxides and reducing agents, substituted ethane-based initiators, etc. can be used. As examples of photoinitiators, α-ketol-based photoinitiators, acetophenone-based photoinitiators, benzoin ether-based photoinitiators, ketal-based photoinitiators, aromatic sulfonyl chloride-based photoinitiators, photoactive oxime-based photoinitiators, benzophenone-based photoinitiators, thioxanthone-based photoinitiators, acylphosphine oxide-based photoinitiators, etc. can be cited. The polymerization initiator can be used alone or two or more can be appropriately combined.

[0121] The usage amount of the polymerization initiator can be the usual usage amount. For example, it can be selected from the range of about 0.005 to 1 part by weight (typically, 0.01 to 1 part by weight) relative to 100 parts by weight of all monomer raw materials. In addition, when the polymerization initiator is also used as a photoinitiator, the usage amount of the polymerization initiator can be set considering this situation.

[0122] In the above polymerization, various known chain transfer agents (which can also be understood as molecular weight regulators or degree of polymerization regulators) can be used as needed. As the chain transfer agent, mercaptans such as n-dodecyl mercaptan, tert-dodecyl mercaptan, mercaptoacetic acid, and α-thioglycerol can be used. Alternatively, a chain transfer agent that does not contain a sulfur atom (non-sulfur-based chain transfer agent) can be used. Specific examples of the non-sulfur-based chain transfer agent include anilines such as N,N-dimethylaniline and N,N-diethylaniline; terpenoids such as α-pinene and terpinolene; styrenes such as α-methylstyrene and α-methylstyrene dimer; compounds having a benzylidene group such as dibenzylideneacetone, cinnamyl alcohol, and cinnamaldehyde; hydroquinones such as hydroquinone and naphthalenediol; quinones such as benzoquinone and naphthoquinone; olefins such as 2,3-dimethyl-2-butene and 1,5-cyclooctadiene; alcohols such as phenol, benzyl alcohol, and allyl alcohol; benzyl hydrogens such as diphenylbenzene and triphenylbenzene; and the like.

[0123] The chain transfer agent can be used alone or in combination of two or more. When using a chain transfer agent, its usage amount can be, for example, about 0.01 to 1 part by weight relative to 100 parts by weight of the monomer raw material. The technology disclosed in this specification can also be preferably implemented by not using a chain transfer agent.

[0124] The molecular weight of the acrylic polymer is not particularly limited and can be set within an appropriate range according to the required performance. The weight average molecular weight (Mw) of the acrylic polymer is usually about 10×10 4 or more (for example, 20×10 4 or more). From the viewpoint of achieving good balance between cohesion and adhesion simultaneously, it is preferably greater than 30×10 4 , preferably about 40×10 4 or more, can be about 50×10 4 or more, can be about 55×10 4 or more. The upper limit of Mw of the acrylic polymer is not particularly limited. From the viewpoint of the coatability of the adhesive composition, the Mw of the acrylic polymer is usually preferably about 500×10 4 or less, for example, can be about 150×10 4 or less, can be about 75×10 4 or less. The above Mw can be the Mw of the acrylic polymer in either the adhesive composition or the adhesive layer.

[0125] As used herein, Mw refers to the value converted according to standard polystyrene obtained by gel permeation chromatography (GPC). As the GPC apparatus, for example, the model "HLC-8320GPC" (column: TSKgel GMH-H(S), manufactured by Tosoh Corporation) can be used. The same applies to the examples described later.

[0126] The acrylic adhesive layer may further contain a polymer other than the acrylic polymer as a sub-polymer as needed. As the above-mentioned sub-polymer, polymers other than the acrylic polymers among the various polymers exemplified as the polymers that can be contained in the adhesive layer are preferably exemplified. When the adhesive layer disclosed in this specification is an acrylic adhesive layer containing not only an acrylic polymer but also a sub-polymer, the content of the sub-polymer is preferably less than 100 parts by weight, more preferably 50 parts by weight or less, still more preferably 30 parts by weight or less, and further preferably 10 parts by weight or less, relative to 100 parts by weight of the acrylic polymer. The content of the sub-polymer can be 5 parts by weight or less, and can be 1 part by weight or less, relative to 100 parts by weight of the acrylic polymer. The technology disclosed in this specification can be preferably implemented, for example, in such a manner that 99.5 to 100% by weight of the polymers contained in the adhesive layer are acrylic polymers.

[0127] (Adhesive layer other than acrylic)

[0128] The adhesive layer constituting the adhesive surface in the adhesive sheet disclosed in this specification can be an adhesive layer based on a polymer other than the acrylic polymer, that is, an adhesive layer other than acrylic. For the adhesive layer other than acrylic, in addition to the base polymer, a sub-polymer other than the base polymer can be further contained as needed. In this case, the content of the sub-polymer in the adhesive layer other than acrylic can be selected from the above-mentioned contents exemplified as the content of the sub-polymer in the acrylic adhesive layer. The adhesive layer other than acrylic can be an adhesive layer containing an acrylic polymer as a sub-polymer.

[0129] (Glass transition temperature)

[0130] The glass transition temperature (Tg) of the base polymer (e.g., acrylic polymer) of the adhesive layer constituting the adhesive surface is preferably about 15°C or lower. In some embodiments, from the viewpoints of adhesion to adherends (e.g., followability to the surface shape of adherends), the above Tg is preferably 10°C or lower, more preferably 0°C or lower, and may be -10°C or lower or -20°C or lower. Additionally, from the viewpoints of the cohesiveness of the adhesive and ease of light peeling based on water peeling, the Tg of the base polymer may be, for example, -75°C or higher, may be -60°C or higher, may be -50°C or higher. In some embodiments, the Tg of the base polymer may be -45°C or higher, may be -40°C or higher.

[0131] Here, in this specification, the glass transition temperature (Tg) of a polymer refers to the glass transition temperature calculated using the Fox equation based on the composition of the monomer raw materials constituting the polymer. The so-called Fox equation is, as shown below, a relational expression between the Tg of a copolymer and the glass transition temperatures Tgi of the homopolymers obtained by homopolymerizing the monomers constituting the copolymer respectively.

[0132] 1 / Tg = Σ(Wi / Tgi)

[0133] It should be noted that in the above Fox equation, Tg represents the glass transition temperature of the copolymer (unit: K), Wi represents the weight fraction (copolymerization ratio based on weight) of monomer i in the copolymer, and Tgi represents the glass transition temperature of the homopolymer of monomer i (unit: K).

[0134] As the glass transition temperature of the homopolymer used in the calculation of Tg, the values described in known materials are used. For example, for the monomers listed below, the following values are used as the glass transition temperatures of the homopolymers of these monomers.

[0135]

[0136] For the glass transition temperatures of the homopolymers of monomers other than those exemplified above, the values described in "Polymer Handbook" (3rd Edition, John Wiley & Sons, Inc., 1989) are used. When multiple values are described in this document, the highest value is adopted.

[0137] For monomers whose glass transition temperatures of homopolymers are not described in the above-mentioned Polymer Handbook, the values obtained by the following measurement method are used (see Japanese Patent Application Laid-Open No. 2007-51271). Specifically, into a reactor equipped with a thermometer, a stirrer, a nitrogen inlet tube, and a reflux condenser, 100 parts by weight of a monomer, 0.2 parts by weight of azobisisobutyronitrile, and 200 parts by weight of ethyl acetate as a polymerization solvent are charged, and stirring is carried out for 1 hour while flowing nitrogen. By operating as described above, the oxygen in the polymerization system is removed, and then the temperature is raised to 63°C and the reaction is carried out for 10 hours. Next, it is cooled to room temperature to obtain a homopolymer solution having a solid content concentration of 33% by weight. Next, the homopolymer solution is cast and coated on a release liner and dried to produce a test sample (sheet-like homopolymer) having a thickness of about 2 mm. The test sample is punched into a disc shape with a diameter of 7.9 mm, clamped with parallel plates, and using a viscoelasticity tester (ARES, manufactured by Rheometrics Inc.), while applying a shear strain of 1 Hz, the viscoelasticity is measured by a shear mode under the conditions that the temperature range is -70 to 150°C and the heating rate is 5°C / minute, and the peak temperature of tanδ is taken as the Tg of the homopolymer.

[0138] (Compound A)

[0139] If necessary, a heat-resistant release agent may be contained in the adhesive layer (preferably a UV-curable adhesive layer). As the heat-resistant release agent, at least one compound A selected from the group consisting of a surfactant and a compound having a polyoxyalkylene skeleton can be used. By containing the above heat-resistant release agent in the adhesive layer, the effect of suppressing the increase in the peel strength of the adhesive sheet after UV irradiation due to exposure to high temperature can be exerted. For example, by containing a heat-resistant release agent in the adhesive layer, the conventional peel strength Fd a2 , Fd b2 and the water peel strength Fw a2 , Fw b2 can be decreased by at least one of them. As the reason for obtaining such an effect, although not particularly limited to this explanation, it can be considered as follows: Generally, by high-temperature exposure, the adhesion between the adherend and the adhesive layer progresses and the peel strength may increase. However, due to the presence of a heat-resistant release agent on the surface of the adhesive layer, the increase in the peel strength can be suppressed. The surfactant and the compound having a polyoxyalkylene skeleton that can be used as the above heat-resistant release agent both have hydrophilic regions, and thus, it is easy to moderately bias and exist on the surface of the adhesive layer. Therefore, the increase in the above peel strength can be effectively suppressed. In addition, as described above, the heat-resistant release agent has a hydrophilic region and is easy to moderately bias and exist on the surface of the adhesive layer. Thus, it can also function as a water peel additive that contributes to the light peelability of the adhesive sheet based on water peel after UV irradiation.

[0140] As the surfactant and the compound having a polyoxyalkylene skeleton, one or more of known surfactants and compounds having a polyoxyalkylene skeleton can be used without particular limitation. Compound A is typically preferably contained in the adhesive layer in a free form. It should be noted that among the above surfactants, there are compounds having a polyoxyalkylene skeleton, and vice versa, which goes without saying.

[0141] As the surfactant that can be used as Compound A, known nonionic surfactants, anionic surfactants, cationic surfactants, etc. can be used. Among them, nonionic surfactants are preferred. The surfactant can be used alone or in combination of two or more.

[0142] Examples of nonionic surfactants include polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether and other polyoxyethylene alkyl ethers; polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether and other polyoxyethylene alkylphenyl ethers; polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene monooleate and other polyoxyethylene fatty acid esters; sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate and other sorbitan fatty acid esters; polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan triisostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate and other polyoxyethylene sorbitan fatty acid esters; polyoxyethylene glyceryl ether fatty acid ester; polyoxyethylene-polyoxypropylene block copolymer; and so on. The nonionic surfactant can be a reactive surfactant having a radically polymerizable functional group such as an allyl group, (meth)allyl group, vinyl group, (meth)acryloyl group (for example, a nonionic reactive surfactant such as polyoxyethylene nonyl allylphenyl ether). These nonionic surfactants can be used alone or in combination of two or more. From the viewpoint of appropriately exerting the effect brought about by the moderate deviation of Compound A on the surface of the adhesive layer and improving the performance stability of the adhesive sheet, a (non-reactive) nonionic surfactant not having the above-mentioned radically polymerizable functional group is preferably used.

[0143] Examples of anionic surfactants include alkylbenzene sulfonates such as nonylbenzene sulfonate and dodecylbenzene sulfonate (e.g., sodium dodecylbenzene sulfonate); alkyl sulfates such as lauryl sulfate (e.g., sodium lauryl sulfate, ammonium lauryl sulfate) and octadecyl sulfate; fatty acid salts; polyoxyethylene alkyl ether sulfates such as polyoxyethylene octadecyl ether sulfate and polyoxyethylene lauryl ether sulfate (e.g., sodium polyoxyethylene alkyl ether sulfate), polyoxyethylene alkyl phenyl ether sulfates such as polyoxyethylene lauryl phenyl ether sulfate (e.g., ammonium polyoxyethylene alkyl phenyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate, etc.), and polyether sulfates such as polyoxyethylene styrenated phenyl ether sulfate; polyoxyethylene alkyl ether phosphates such as polyoxyethylene stearyl ether phosphate and polyoxyethylene lauryl ether phosphate; salts of the above polyoxyethylene alkyl ether phosphates such as sodium salts and potassium salts of polyoxyethylene alkyl ether phosphates; sulfosuccinates such as lauryl sulfosuccinate and polyoxyethylene lauryl sulfosuccinate (e.g., sodium polyoxyethylene alkyl sulfosuccinate); polyoxyethylene alkyl ether acetates; and so on. When the anionic surfactant forms a salt, the salt can be, for example, a metal salt such as a sodium salt, potassium salt, calcium salt, or magnesium salt (preferably a salt of a monovalent metal), an ammonium salt, an amine salt, etc. The anionic surfactant can be used alone or in combination of two or more. From the same viewpoint as the nonionic surfactant, a non-reactive anionic surfactant is preferably used.

[0144] Examples of cationic surfactants include polyetheramines such as polyoxyethylene lauryl amine and polyoxyethylene stearyl amine. The cationic surfactant can be used alone or in combination of two or more.

[0145] Examples of the compound having a polyoxyalkylene skeleton that can be used as Compound A include polyalkylene glycols such as polyethylene glycol (PEG) and polypropylene glycol (PPG); polyethers containing a polyoxyethylene unit, polyethers containing a polyoxypropylene unit, and compounds containing an oxyethylene unit and an oxypropylene unit (the arrangement of these units can be random or block-like); their derivatives; and so on. In addition, compounds having a polyoxyalkylene skeleton among the above nonionic, anionic, and cationic surfactants can also be used. They can be used alone or in combination of two or more. Among them, compounds containing a polyoxyethylene skeleton (also referred to as a polyoxyethylene segment) are preferably used, and PEG is more preferably used.

[0146] The molecular weight (chemical formula weight) of the compound having a polyoxyalkylene skeleton (e.g., polyethylene glycol) is not particularly limited. From the viewpoint of homogeneous mixing property, for example, it is preferably less than 1000, more preferably about 600 or less (e.g., 500 or less). The lower limit of the molecular weight of the compound having a polyoxyalkylene skeleton (e.g., polyethylene glycol) is not particularly limited, and a compound having a molecular weight of about 100 or more (e.g., about 200 or more, further about 300 or more) can be preferably used.

[0147] The adhesive layer containing Compound A can typically be formed from an adhesive composition containing the Compound A. The adhesive composition containing Compound A is preferably prepared by a method including a step of adding Compound A in a solvent-free form or in the form of an organic solvent solution. The so-called solvent-free form mentioned above means a form not diluted with an organic solvent or water that does not form an adhesive layer, and for example, it can be a form formed by Compound A. The organic solvent used in the preparation of the above organic solvent solution can be appropriately selected from known organic solvents. As specific examples of the above organic solvent, the same solvents as those used in the solution polymerization described later can be cited. As a preferred example, ethyl acetate, a mixed solvent containing ethyl acetate (which can be a mixed solvent of ethyl acetate and toluene), toluene, and a mixed solvent containing toluene can be cited. For example, ethyl acetate or a mixed solvent mainly composed of ethyl acetate can be preferably used. For a solvent-type or active energy ray-curable adhesive composition, from the viewpoint of preventing water from being introduced into the adhesive composition, in some embodiments, it is preferable to add Compound A in the form of an organic solvent solution that is substantially free of water (e.g., the water content is less than 10 parts by weight, less than 5 parts by weight, or less than 1 part by weight relative to 100 parts by weight of Compound A). Thereby, an adhesive layer with higher uniformity can be formed.

[0148] In some embodiments, as Compound A, from the aspect of being easily and well uniformly incorporated into the adhesive composition, a nonionic compound can be preferably used. With an adhesive composition in which Compound A is well uniformly incorporated, there is a tendency to form an adhesive layer in which Compound A is present with good surface uniformity. This is preferable from the viewpoint of making the peeling of the adhesive sheet from the adherend proceed more smoothly and reducing the load on the adherend due to fluctuations in the peeling force (e.g., vibrations and impacts accompanying the fluctuations).

[0149] The HLB of Compound A is not particularly limited. For example, the HLB of Compound A can be 1 or more, or 3 or more. The HLB of Compound A is preferably 5 or more, can be 6 or more, can be 8 or more, and can be 9 or more. Thus, there is a tendency for suitable water peelability to be exhibited. The HLB of Compound A is more preferably 10 or more, further preferably 11 or more, further preferably 12 or more, particularly preferably 13 or more, can be 14 or more, can be 15 or more, and further can be 16 or more. By using Compound A having an HLB within the above range, light peelability based on water peeling can be more effectively exhibited. The upper limit of the above HLB is 20 or less, and can be, for example, 18 or less. In some embodiments, for example, from the viewpoint of compatibility, the HLB of Compound A can be 16 or less, and can be, for example, 15 or less.

[0150] It should be noted that the HLB in this specification is the Hydrophile-Lipophile Balance value proposed by Griffin, which is a value representing the degree of affinity of a surfactant for water and oil, and represents the ratio of hydrophilicity to lipophilicity with a numerical value between 0 and 20. The definition of HLB is as described in, for example, W.C. Griffin: J.Soc.CosmeticChemists, 1, 311 (1949), co-authored by Takahashi Tominari, Nanba Yoshirou, Koike Motoki, and Kobayashi Masao, "Surfactant Handbook", 3rd edition, published by Kogyo Tosho Co., Ltd. on November 25, 1972, pp. 179-182, etc. Compound A having the above HLB can be selected as needed with reference to the above references, etc., based on the common technical knowledge of those skilled in the art.

[0151] In some embodiments, as Compound A, from the viewpoint of affinity with the aqueous peeling liquid, a compound having 2 or more hydroxyl groups in one molecule is preferred, and a compound having 3 or more hydroxyl groups in one molecule is more preferred. Examples of Compound A having 2 or 3 or more hydroxyl groups in one molecule include sorbitan monoesters, polyoxyalkylene sorbitan monoesters, polyoxyalkylene glyceryl ethers, polyoxyalkylene diglyceryl ethers, polyoxyalkylene glyceryl ether monoesters, etc. The upper limit of the number of hydroxyl groups in one molecule of Compound A is not particularly limited, and from the viewpoints of solubility in organic solvents and ease of preparation of the adhesive composition, it is usually preferably 10 or less, can be 8 or less, can be 6 or less, and can be 4 or less.

[0152] In some embodiments, as Compound A, from the perspective of solubility in an organic solvent (e.g., esters such as ethyl acetate), a nonionic compound having a fatty acid ester structure can be preferably selected. The compound A having a fatty acid ester structure can also be advantageous in terms of compatibility within the adhesive layer. For example, as Compound A contained in the acrylic adhesive layer, a compound A having a fatty acid ester structure can be preferably employed. Examples of the nonionic compound having a fatty acid ester structure include sorbitan fatty acid esters, polyoxyalkylene fatty acid esters, polyoxyalkylene fatty acid monoesters, etc.

[0153] In some embodiments, as Compound A, from the perspective of ease of preparation of the organic solvent solution, it is preferably liquid at room temperature (here, 25°C) in the form of 100% solid content.

[0154] In addition, in some embodiments, as Compound A, a compound A that does not phase-separate and dissolves in the following Test II is preferred, and a compound A that does not phase-separate and dissolves in the following Test I is more preferred. It should be noted that the following Tests I and II use Compound A in the form of 100% solid content and are carried out in an environment at room temperature (23 - 25°C).

[0155] [Test I]

[0156] Put 90 g of ethyl acetate and 10 g of Compound A into a 200-milliliter (mL) container, stir with a glass rod for 1 minute, then let it stand. After 5 minutes, visually observe the presence or absence of phase separation.

[0157] [Test II]

[0158] Put 90 g of ethyl acetate and 10 g of Compound A into a 200-mL container, stir with a glass rod for 1 minute, then use an ultrasonic dispersing device to perform a 10-minute treatment at 35 kHz, further stir with a glass rod for 1 minute, then let it stand. After 5 minutes, visually observe the presence or absence of phase separation.

[0159] It should be noted that as the ultrasonic dispersing device, a machine model "ULTRASONIC CLEANER" manufactured by AS ONE Corporation or a device equivalent thereto can be used.

[0160] The amount of Compound A used is not particularly limited and can be set in such a way that the usage effect corresponding to the purpose can be appropriately exerted (for example, the effect of suppressing the increase in the peel strength of the adhesive sheet after UV irradiation due to exposure to high temperature, and / or the effect of contributing to easy peelability based on water peeling). In some embodiments, regarding the amount of Compound A used, relative to 100 parts by weight of the base polymer, it can be, for example, about 5 parts by weight or less. From the viewpoints of the bonding reliability to the adherend and the water resistance reliability at the stage where peeling is not desired, it is preferably about 3 parts by weight or less, more preferably less than 2 parts by weight, still more preferably less than 1 part by weight, and can be less than 0.8 part by weight, can be less than 0.6 part by weight, can be less than 0.4 part by weight, can be less than 0.2 part by weight, can be less than 0.1 part by weight. For Compound A with a high HLB (for example, 5 or more, preferably 10 or more), even when added in a small amount, there is a tendency to easily exhibit good water peelability. In addition, the amount of Compound A relative to 100 parts by weight of the base polymer can be, for example, 0.001 part by weight or more. From the viewpoints of enabling Compound A to exist uniformly on the surface of the adhesive layer and making the peeling of the adhesive sheet from the adherend proceed more smoothly, it is generally preferably 0.01 part by weight or more, and preferably 0.03 part by weight or more (for example, 0.1 part by weight or more). In a composition that emphasizes water peelability, the amount of Compound A relative to 100 parts by weight of the base polymer can be 0.3 part by weight or more (for example, 0.5 part by weight or more).

[0161] (Crosslinking agent)

[0162] In the adhesive layer (preferably a UV-curable adhesive layer), for the purpose of adjusting cohesion, etc., a crosslinking agent can be used as needed. The crosslinking agent can be contained in the adhesive layer in the form after the crosslinking reaction or in the form before the crosslinking reaction. The type of the crosslinking agent is not particularly limited. For example, it can be selected from known crosslinking agents according to the composition of the adhesive composition in such a way that the crosslinking agent exerts an appropriate crosslinking function in the adhesive layer. Examples of the crosslinking agent that can be used include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, carbodiimide-based crosslinking agents, melamine-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, hydrazine-based crosslinking agents, amine-based crosslinking agents, etc. They can be used alone or in combination of two or more. In some preferred embodiments, at least an isocyanate-based crosslinking agent is used as the crosslinking agent. The isocyanate-based crosslinking agent and other crosslinking agents (for example, epoxy-based crosslinking agents) can be used in combination.

[0163] As the isocyanate-based crosslinking agent, polyfunctional isocyanate compounds having two or more functional groups can be used. Examples thereof include aromatic isocyanates such as toluene diisocyanate, xylene diisocyanate, polymethylene polyphenyl diisocyanate, tris(4-isocyanatophenyl) thiophosphate, diphenylmethane diisocyanate; alicyclic isocyanates such as isophorone diisocyanate; aliphatic isocyanates such as 1,6-hexamethylene diisocyanate; and the like. Examples of commercially available products include isocyanate adducts such as trimethylolpropane / toluene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name “Coronate L”), trimethylolpropane / 1,6-hexamethylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name “Coronate HL”), isocyanurate of 1,6-hexamethylene diisocyanate (manufactured by Tosoh Corporation, trade name “Coronate HX”).

[0164] As the epoxy-based crosslinking agent, an epoxy-based crosslinking agent having two or more epoxy groups in one molecule can be used without particular limitation. An epoxy-based crosslinking agent having 3 to 5 epoxy groups in one molecule is preferred. Specific examples of the epoxy-based crosslinking agent include N,N,N’,N’-tetraglycidyl-m-xylenediamine, 1,3-bis(N,N-diglycidylaminomethyl) cyclohexane, 1,6-hexanediol diglycidyl ether, polyethylene glycol diglycidyl ether, polyglycerol polyglycidyl ether and the like. Examples of commercially available products of the epoxy-based crosslinking agent include products with the trade names “TETRAD-X” and “TETRAD-C” manufactured by Mitsubishi Gas Chemical Company, products with the trade name “EPICLON CR-5L” manufactured by DIC Corporation, products with the trade name “Denacol EX-512” manufactured by Nagase ChemteX Corporation, products with the trade name “TEPIC-G” manufactured by Nissan Chemical Industries, Ltd.

[0165] As the oxazoline-based crosslinking agent, an oxazoline-based crosslinking agent having one or more oxazoline groups in one molecule can be used without particular limitation.

[0166] Examples of the aziridine-based crosslinking agent include trimethylolpropane tris[3-(1-aziridinyl) propionate], trimethylolpropane tris[3-(1-(2-methyl) aziridinyl) propionate] and the like.

[0167] As the carbodiimide-based crosslinking agent, a low molecular weight compound or a high molecular weight compound having two or more carbodiimide groups can be used.

[0168] Typically, the metal chelate crosslinking agent can be a substance having a structure formed by covalent bonding or coordination bonding of a polyvalent metal with an organic compound. Examples of the polyvalent metal atoms include Al, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Ba, Mo, La, Sn, Ti, etc. Among them, Al, Zr, and Ti are preferred. In addition, examples of the organic compound include alkyl esters, alcohol compounds, carboxylic acid compounds, ether compounds, ketone compounds, etc. Typically, the metal chelate crosslinking agent can be a compound having a structure in which an oxygen atom in the organic compound is bonded (covalently bonded or coordinately bonded) to the polyvalent metal.

[0169] In some embodiments, a peroxide can be used as the crosslinking agent. Examples of the peroxide include bis(2-ethylhexyl) peroxydicarbonate, bis(4-tert-butylcyclohexyl) peroxydicarbonate, di-sec-butyl peroxydicarbonate, tert-butyl peroxyneodecanoate, tert-hexyl peroxyneopentanoate, tert-butyl peroxyneopentanoate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutyl peroxyisobutyrate, benzoyl peroxide, etc. Among these, bis(4-tert-butylcyclohexyl) peroxydicarbonate, dilauroyl peroxide, benzoyl peroxide, etc. can be cited as peroxides with particularly excellent crosslinking reaction efficiency. It should be noted that when a peroxide is used as the above polymerization initiator, the peroxide remaining without being used in the polymerization reaction can also be used in the crosslinking reaction. In this case, the residual amount of the peroxide is quantified, and when the proportion of the peroxide does not meet the specified amount, the peroxide can be added as needed to make it the specified amount. The quantification of the peroxide can be carried out by the method described in Japanese Patent No. 4971517.

[0170] The amount of the crosslinking agent used (in the case of using two or more crosslinking agents, the total amount thereof) is not particularly limited and can be appropriately set in a manner that can achieve the desired usage effect. For an adhesive sheet having an adhesive surface composed of an active energy ray-curable adhesive layer, from the viewpoint of exhibiting appropriate cohesiveness before the curing treatment based on active energy rays, the amount of the crosslinking agent used is usually preferably about 0.005 parts by weight or more, more preferably about 0.01 parts by weight or more, and can be about 0.05 parts by weight or more, can be about 0.1 parts by weight or more, can be about 0.2 parts by weight or more, per 100 parts by weight of the base polymer (for example, an acrylic polymer). When increasing the amount of the crosslinking agent used, it becomes advantageous from the viewpoint of suppressing an increase in the peel strength after the curing treatment due to high-temperature exposure after adhesion. From the above viewpoints, in some embodiments, the amount of the crosslinking agent used is preferably more than 0.3 parts by weight, more preferably more than 0.5 parts by weight, and can be more than 1.0 parts by weight, can be more than 1.5 parts by weight, can be more than 2.0 parts by weight, can be more than 3.0 parts by weight, can be more than 4.0 parts by weight, per 100 parts by weight of the base polymer. For an adhesive sheet that can be used by the method of water peeling after the curing treatment based on active energy rays, if the amount of the crosslinking agent used is increased, the strain due to curing shrinkage will be easily maintained until the supply of the aqueous peeling liquid, and the effect of light peeling brought about by the application of the water peeling method can be exhibited more favorably.

[0171] In addition, the amount of the crosslinking agent used is usually preferably about 15 parts by weight or less, and from the viewpoints of adhesion to the adherend, bonding reliability, etc. during semiconductor processing, it is more preferably about 12 parts by weight or less, and even more preferably about 10 parts by weight or less, per 100 parts by weight of the base polymer.

[0172] In some embodiments where more importance is attached to the initial conventional peel strength Fd0, the amount of the crosslinking agent used can be, for example, less than 7.0 parts by weight, can be less than 5.0 parts by weight, can be less than 3.0 parts by weight, can be less than 2.0 parts by weight, can be less than 1.0 parts by weight, can be less than 0.5 parts by weight, per 100 parts by weight of the base polymer. In an embodiment containing a certain amount (for example, more than 0.2 parts by weight per 100 parts by weight of the base polymer) of Compound A, when the amount of the crosslinking agent used is not excessive, it becomes advantageous from the viewpoint of suppressing a decrease in the initial conventional peel strength Fd0 due to excessive bias of Compound A to the surface of the adhesive layer.

[0173] In the method of using an isocyanate-based crosslinking agent as a crosslinking agent, from the viewpoints of having appropriate cohesiveness before the curing treatment and suppressing an increase in the peeling force after the curing treatment due to high-temperature exposure after adhesion, the amount of the isocyanate-based crosslinking agent used is generally preferably about 0.005 parts by weight or more, more preferably about 0.01 parts by weight or more, may be about 0.05 parts by weight or more, may be about 0.1 parts by weight or more, may be about 0.2 parts by weight or more, may be greater than 0.3 parts by weight, may be greater than 0.5 parts by weight, may be greater than 1.0 parts by weight, may be greater than 1.5 parts by weight, may be greater than 2.0 parts by weight, may be greater than 3.0 parts by weight, may be greater than 4.0 parts by weight, based on 100 parts by weight of the base polymer. For an adhesive sheet that can be used by the method of water peeling after the curing treatment based on active energy rays, by increasing the amount of the isocyanate-based crosslinking agent used, the effect of light peeling brought about by the application of the water peeling method can be exhibited more favorably.

[0174] In addition, the amount of the isocyanate-based crosslinking agent used is generally preferably about 15 parts by weight or less, more preferably about 12 parts by weight or less, even more preferably about 10 parts by weight or less, may be less than 7.0 parts by weight, may be less than 5.0 parts by weight, may be less than 4.0 parts by weight, may be less than 3.0 parts by weight, may be less than 2.0 parts by weight, may be less than 1.0 parts by weight, may be less than 0.5 parts by weight, based on 100 parts by weight of the base polymer. From the viewpoints of adhesion to an adherend and bonding reliability during semiconductor processing, etc., in the method containing a certain amount (for example, greater than 0.2 parts by weight based on 100 parts by weight of the base polymer) of Compound A, it becomes advantageous also from the viewpoint of suppressing a decrease in the initial conventional peeling force Fd0 due to excessive bias of Compound A to the surface of the adhesive layer.

[0175] In order to carry out the crosslinking reaction more effectively, a crosslinking catalyst can be used. Examples of the crosslinking catalyst include metal-based crosslinking catalysts such as tetra-n-butyl titanate, tetra-isopropyl titanate, iron acetylacetonate, butyltin oxide, and dioctyltin dilaurate. Among them, tin-based crosslinking catalysts such as dioctyltin dilaurate are preferred. The amount of the crosslinking catalyst used is not particularly limited. The amount of the crosslinking catalyst used based on 100 parts by weight of the base polymer can be, for example, about 0.0001 parts by weight or more and 1 part by weight or less, can be 0.001 parts by weight or more and 0.1 part by weight or less, can be 0.005 parts by weight or more and 0.5 part by weight or less.

[0176] (Polyfunctional monomer)

[0177] In the adhesive layer, a polyfunctional monomer can be used as needed. For the polyfunctional monomer, it can be used in place of the above-mentioned crosslinking agent or in combination with the crosslinking agent, and can play a role for the purpose of adjusting cohesion and the like. As the polyfunctional monomer, a compound having two or more carbon-carbon double bonds (for example, an ethylenically unsaturated group such as (meth)acryloyl) can be used. The polyfunctional monomer can be contained in the adhesive layer in an unreacted form or in a form after reaction (after crosslinking). The adhesive layer containing the unreacted polyfunctional monomer can be the following active energy ray-curable adhesive layer: by irradiating the adhesive layer with active energy rays such as ultraviolet rays, the above-mentioned polyfunctional monomer reacts to form a crosslinked structure.

[0178] Examples of the polyfunctional monomer include ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, allyl (meth)acrylate, vinyl (meth)acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butanediol (meth)acrylate, hexanediol di(meth)acrylate, and the like. Among them, trimethylolpropane tri(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and dipentaerythritol hexa(meth)acrylate can be suitably used. The polyfunctional monomer can be used alone or in combination of two or more.

[0179] The appropriate amount of use of a polyfunctional monomer varies depending on its molecular weight, the number of functional groups, etc. Generally, it is suitable in the range of about 0.01 to 3.0 parts by weight relative to 100 parts by weight of a base polymer (for example, an acrylic polymer). In some embodiments, the amount of the polyfunctional monomer used relative to 100 parts by weight of the base polymer can be, for example, 0.02 parts by weight or more, 0.1 parts by weight or more, 0.5 parts by weight or more, 1.0 parts by weight or more, or 2.0 parts by weight or more. By increasing the amount of the polyfunctional monomer used, there is a tendency to obtain higher cohesion. On the other hand, from the viewpoint of avoiding a decrease in the adhesion to the adherend and a decrease in the storage stability of the adhesive sheet due to excessive increase in cohesion, the amount of the polyfunctional monomer used relative to 100 parts by weight of the base polymer can be, for example, 10 parts by weight or less, 5.0 parts by weight or less, or 3.0 parts by weight or less. Alternatively, the polyfunctional monomer may not be used. For example, an adhesive layer containing a polymer having a structure (such as a carbon-carbon double bond, a benzophenone structure, etc.) that causes a crosslinking reaction upon irradiation with an active energy ray can be an adhesive layer that substantially does not contain unreacted polyfunctional monomers or an adhesive layer formed from an adhesive composition that substantially does not contain polyfunctional monomers. Here, the so-called adhesive composition substantially does not contain polyfunctional monomers means that the amount of the polyfunctional monomer is less than 0.05 parts by weight (for example, less than 0.01 parts by weight) relative to 100 parts by weight of the base polymer.

[0180] (Other optional components)

[0181] In the adhesive layer (preferably a UV-curable adhesive layer), if necessary, a tackifying resin (for example, a tackifying resin such as a rosin-based, petroleum-based, terpene-based, phenol-based, or ketone-based tackifying resin), a viscosity modifier (for example, a thickener), a leveling agent, a plasticizer, a filler, a coloring agent such as a pigment or a dye, a stabilizer, a preservative, an antioxidant, an anti-aging agent, etc., various additives conventional in the field of adhesives can be included as other optional components. Regarding such various additives, they can be used by conventional methods using known additives, and since they are not substances that particularly impart characteristics to the present invention, detailed descriptions thereof are omitted.

[0182] From the viewpoint of achieving good balance between the adhesion to the adherend during semiconductor processing and the peelability during the removal of the adherend (e.g., peelability based on water peeling), in some embodiments, regarding the content of the tackifying resin in the adhesive layer, relative to 100 parts by weight of the base polymer, for example, it is less than 5 parts by weight, further can be less than 3 parts by weight, can be less than 1 part by weight, can be less than 0.5 part by weight, can be less than 0.1 part by weight. It can be an adhesive layer that substantially does not contain a tackifying resin (e.g., the content of the adhesive layer relative to 100 parts by weight of the base polymer is 0 to 0.05 parts by weight). When the content of the tackifying resin is limited as described above, for example, it can be advantageous from the viewpoint of improving the curability of the active energy ray curable adhesive layer.

[0183] In some preferred embodiments, the above-mentioned adhesive layer can have a composition in which the content of the polymer (typically, the base polymer) accounts for about 80% by weight or more of the total weight of the adhesive layer. Thereby, the effect of reducing the peel force by applying water peeling (light peeling effect) can be ideally achieved. From such a viewpoint, the content of the above-mentioned polymer is preferably about 85% by weight or more of the total weight of the adhesive layer, more preferably about 90% by weight or more, can be about 92% by weight or more, can be about 95% by weight or more.

[0184] (Active energy ray curable adhesive layer)

[0185] The adhesive layer constituting at least one adhesive surface of the adhesive sheet disclosed in this specification is preferably an adhesive layer (active energy ray curable adhesive layer) composed of an active energy ray curable adhesive. Among them, it is preferably an active energy ray curable adhesive layer configured such that after being attached to the adherend and irradiated with active energy rays, its curing causes the peel force for peeling from the above-mentioned adherend to decrease compared to before irradiation. For an adhesive sheet having such an active energy ray curable adhesive layer, the bonding reliability to the adherend is good before the irradiation of the active energy rays, and by irradiating the active energy rays (preferably followed by supplying an aqueous peeling liquid), the peel force for peeling from the adherend can be rapidly decreased.

[0186] In addition, for the active energy ray-curable adhesive layer, after curing by irradiating active energy rays in the state of being attached to the adherend, it is peeled off by the water peeling method. Thus, the peeling force for peeling from the above adherend can be particularly effectively reduced. As the reason, although not particularly limited to this explanation, it can be considered as follows: When irradiating active energy rays to the active energy ray-curable adhesive layer in the state of being attached to the adherend, due to the sharp curing shrinkage of the adhesive layer, minute floating from the adherend occurs, or strain accumulates in the adhesive layer. If an aqueous peeling liquid is supplied in this state, the infiltration of the aqueous peeling liquid into the interface between the adhesive layer and the adherend proceeds rapidly, and the peeling force effectively decreases. For an adhesive sheet configured to reduce the peeling force by curing the adhesive layer by irradiating active energy rays, after irradiating active energy rays, it is peeled off by the water peeling method. Thus, through the synergistic effect of the decrease in the peeling force due to the curing of the adhesive layer and the decrease in the water peeling force due to the above-mentioned sharp curing shrinkage, a particularly remarkable light peeling effect can be exhibited.

[0187] As a preferred example of the active energy ray-curable adhesive layer, an example in which curability is exhibited by including carbon-carbon double bonds in the adhesive layer can be cited. Carbon-carbon double bonds do not react with moisture, acidity, etc. in the air in a normal storage environment applicable industrially and have stable chemical properties. On the other hand, when free radicals are generated by irradiating active energy rays, a reaction (for example, a polymerization reaction, a crosslinking reaction) occurs and curing takes place. From the viewpoint of ease of handling, etc., as the preferred active energy ray, light (for example, ultraviolet rays) can be cited.

[0188] In the adhesive layer that exhibits curability by including carbon-carbon double bonds, the form of existence of the carbon-carbon double bonds in the adhesive layer is not particularly limited. The above carbon-carbon double bonds can be included in the adhesive layer, for example, in the form of a polymer having a carbon-carbon double bond (for example, a base polymer), a monomer having a carbon-carbon double bond (for example, the above-mentioned unreacted polyfunctional monomer), etc. They can be used alone or in combination of two or more.

[0189] The form of the carbon-carbon double bonds included in the polymer and the form of the carbon-carbon double bonds included in the monomer are not particularly limited. For example, the carbon-carbon double bonds can exist in the polymer or monomer in the form of an ethylenically unsaturated group. Examples of the ethylenically unsaturated group include (meth)acryloyl, vinyl, allyl, methallyl, etc. From the viewpoint of reactivity, (meth)acryloyl is preferred.

[0190] (Polymer having a carbon-carbon double bond)

[0191] In some embodiments, the energy ray curable adhesive layer preferably contains a polymer having a carbon-carbon double bond. Hereinafter, the polymer having a carbon-carbon double bond will also be referred to as "polymer (PD)". For example, a polymer (PD) having a carbon-carbon double bond in the form of an ethylenically unsaturated group is preferred. In some preferred embodiments, the polymer (PD) may be included as a base polymer of the adhesive layer in the energy ray curable adhesive layer. In some other embodiments, the polymer (PD) may be included as an additional component used in addition to a base polymer that does not contain a carbon-carbon double bond in the energy ray curable adhesive layer. The energy ray curable adhesive layer may be one that contains the polymer (PD) as a base polymer and further contains a monomer having a carbon-carbon double bond (e.g., an unreacted polyfunctional monomer) as an additional component.

[0192] The form of the carbon-carbon double bond in the polymer (PD) is not particularly limited. The polymer (PD) may be a polymer having a carbon-carbon double bond in the side chain or a polymer having a carbon-carbon double bond in the main chain. Here, having a carbon-carbon double bond in the main chain includes the case where a carbon-carbon double bond is present in the main chain skeleton of the polymer (PD) and the case where a carbon-carbon double bond is present at the end of the main chain. From the viewpoint of the reactivity of the carbon-carbon double bond, a polymer (PD) having a carbon-carbon double bond in the side chain is preferably employed. The method for including a carbon-carbon double bond in the polymer (PD) is not particularly limited, and an appropriate method may be selected from the methods known to those skilled in the art.

[0193] As the polymer (PD), there is no particular limitation, and an appropriate polymer may be selected in consideration of the properties of the adhesive layer and the like. As the polymer (PD), a polymer (secondary polymer) obtained by introducing a carbon-carbon double bond into a polymer (primary polymer) that does not contain a carbon-carbon double bond or has a lower content ratio of carbon-carbon double bonds than the target by methods such as chemical modification is preferably used.

[0194] As a specific example of the method for introducing a carbon-carbon double bond into the primary polymer, the following method may be mentioned: Prepare a primary polymer obtained by copolymerizing a monomer having a functional group (functional group A), and react the primary polymer with a compound having a functional group (functional group B) and a carbon-carbon double bond that can react with the functional group A in one molecule (hereinafter, also referred to as "unsaturated compound containing functional group B") in such a manner that the carbon-carbon double bond does not disappear. The reaction between the functional group A and the functional group B is preferably a reaction that does not generate free radicals, such as a condensation reaction or an addition reaction.

[0195] Examples of the combination of functional group A and functional group B include the combination of a carboxyl group and an epoxy group, the combination of a carboxyl group and an aziridinyl group, the combination of a hydroxyl group and an isocyanate group, etc. Among them, from the viewpoint of reaction traceability, the combination of a hydroxyl group and an isocyanate group is preferred. In addition, as long as the combination of the above functional groups A and B can obtain a polymer having a carbon-carbon double bond, one of the functional groups in the above combination can be functional group A and the other can be functional group B, or one of the above functional groups can be functional group B and the other can be functional group A. For example, when explained by the combination of a hydroxyl group and an isocyanate group, functional group A can be a hydroxyl group (in this case, functional group B becomes an isocyanate group), or it can be an isocyanate group (in this case, functional group B becomes a hydroxyl group). Among them, a combination in which the primary polymer has a hydroxyl group and the above compound has an isocyanate group is preferred. This combination is particularly preferred when the primary polymer is an acrylic polymer.

[0196] In addition, as a preferred example of a method for obtaining a polymer having a carbon-carbon double bond, the following method can also be cited: using a vinyl alcohol-based polymer (typically, polyvinyl alcohol) as the above primary polymer, and reacting the vinyl alcohol-based polymer (typically, a vinyl alcohol-based polymer not containing a carbon-carbon double bond) with a vinyl halide such as vinyl bromide or an allyl halide such as allyl bromide. In this method, the above reaction can be carried out under appropriate basic conditions, and through this reaction, a vinyl alcohol-based polymer containing a vinyl group in the side chain can be obtained. In addition, for example, a method for preparing a polymer having a carbon-carbon double bond by using a microorganism that produces a polymer as disclosed in Japanese Patent No. 4502363 can be adopted. Various conditions such as the type of microorganism and the microorganism culture conditions in this method can be set by adopting the conditions described in the above patent publication or appropriately changing them within the scope of the common technical knowledge of those skilled in the art.

[0197] Regarding the molar ratio (M A ) of the above functional group A to the molar ratio (M B ) of functional group B (M A / M B ), from the viewpoint of the reactivity of the two, it is usually preferably 0.2 or more, and can be 0.5 or more, can be 0.7 or more, and can be 1.0 or more. In some embodiments, the molar ratio (M A / M B ) can be greater than 1.0, can be greater than 1.5, and can be greater than 2.0. For example, when applying functional group A to other reactions (such as a crosslinking reaction with a crosslinking agent), it is preferred to make the molar ratio (M A / M B ) greater than 1.0. In addition, the molar ratio (M A / M B)For example, it can be 20 or less. In some embodiments, from the perspective of achieving good balance between the adhesion to the adherend before light irradiation and the peelability from the adherend after light irradiation (e.g., peelability based on water peeling), the molar ratio (M A / M B ) is preferably 10 or less, can be 5.0 or less, can be 2.5 or less, can be 1.8 or less, can be 1.5 or less, can be 1.3 or less.

[0198] Regarding the usage amount of the compound having a functional group B and a carbon-carbon double bond (hereinafter, also referred to as "unsaturated compound containing functional group B"). In the range that satisfies the above molar ratio (M A / M B ), relative to 100 parts by weight of the primary polymer having a functional group A, for example, it can be 1.0 part by weight or more, can be 3.0 part by weight or more, can be 5.0 part by weight or more, can be 7.0 part by weight or more. From the perspective of achieving higher-level adhesion before light irradiation and peelability after light irradiation (e.g., peelability based on water peeling) simultaneously, in some embodiments, the usage amount of the unsaturated compound containing functional group B relative to 100 parts by weight of the above primary polymer is preferably 9.0 parts by weight or more, more preferably 10 parts by weight or more, can be 12 parts by weight or more, can be 14 parts by weight or more, can be 16 parts by weight or more. In addition, the usage amount of the unsaturated compound containing functional group B relative to 100 parts by weight of the above primary polymer can be less than 40 parts by weight, generally, it is preferably less than 35 parts by weight, preferably less than 30 parts by weight, can be less than 25 parts by weight, can be less than 20 parts by weight. In some embodiments, the usage amount of the unsaturated compound containing functional group B relative to 100 parts by weight of the above primary polymer can be less than 18 parts by weight, can be less than 16 parts by weight, can be less than 13 parts by weight, can be less than 10 parts by weight, can be less than 7 parts by weight.

[0199] As a preferred example of the polymer having a carbon-carbon double bond, an acrylic polymer having a (meth)acryloyl group introduced into the side chain can be cited. Such an acrylic polymer can be obtained, for example, by reacting an acrylic primary polymer having a hydroxyl group (functional group A) introduced by copolymerization with a compound having a carbon-carbon double bond and an isocyanate group (functional group B) in a manner that the carbon-carbon double bond does not disappear.

[0200] In addition, polymers having a carbon-carbon double bond can be, for example, diene polymers (typically, conjugated diene polymers). Diene polymers (typically, conjugated diene polymers) are typically polymers obtained by polymerizing or copolymerizing dienes (typically, conjugated dienes). Examples of the diene polymers (typically, conjugated diene polymers) include butadiene polymers such as polybutadiene and styrene-butadiene copolymer; isoprene polymers such as polyisoprene and styrene-isoprene copolymer; chloroprene polymers such as polychloroprene; and the like.

[0201] As other examples of the active energy ray-curable adhesive layer, an adhesive layer containing a polymer having a structure other than a carbon-carbon double bond that causes a crosslinking reaction by irradiation with active energy rays can be cited. For example, an adhesive containing a polymer having a benzophenone structure in the side chain can exhibit active energy ray curability by photocrosslinking using the above benzophenone structure. As the polymer having a benzophenone structure in the side chain, an acrylic polymer having a benzophenone structure in the side chain is preferably used.

[0202] (Photoinitiator)

[0203] When ultraviolet rays are used as the active energy rays for curing the active energy ray-curable adhesive layer, from the viewpoint of promoting the reaction or improving the utilization efficiency of light energy, it is preferable to contain a photoinitiator in the above adhesive layer.

[0204] Examples of the above photoinitiator include, for example, benzoin ether-based photoinitiators, acetophenone-based photoinitiators, α-hydroxyketone-based photoinitiators, aromatic sulfonyl chloride-based photoinitiators, photoactive oxime-based photoinitiators, benzoin-based photoinitiators, benzil-based photoinitiators, benzophenone-based photoinitiators, ketal-based photoinitiators, thioxanthone-based photoinitiators, α-aminoketone-based photoinitiators, acylphosphine oxide-based photoinitiators, and the like. The photoinitiator can be used alone or in combination of two or more.

[0205] Examples of benzoin ether-based photoinitiators include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethane-1-one, anisole methyl ether, etc. Examples of acetophenone-based photoinitiators include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxy-cyclohexyl-phenyl ketone, 4-phenoxydichloroacetophenone, 4-tert-butyl-dichloroacetophenone, etc. Examples of α-hydroxy ketone-based photoinitiators include 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, etc. Examples of aromatic sulfonyl chloride-based photoinitiators include 2-naphthalenesulfonyl chloride, etc. Examples of photoactive oxime-based photoinitiators include 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime, etc. Examples of benzoin-based photoinitiators include benzoin, etc. Examples of benzil-based photoinitiators include benzil, etc. Examples of benzophenone-based photoinitiators include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexylphenyl ketone, etc. Examples of ketal-based photoinitiators include benzil dimethyl ketal, etc. Examples of thioxanthone-based photoinitiators include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, dodecylthioxanthone, etc. Examples of α-amino ketone-based photoinitiators include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, etc. Examples of acylphosphine oxide-based photoinitiators include 2,4,6-trimethylbenzoyl diphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, etc.

[0206] As the above photoinitiators, commercially available products can be used. Examples include products with trade names "Omnirad 651", "Omnirad 184", "Omnirad 2959", "Omnirad 907", "Omnirad 369", "Omnirad 1173", "Omnirad TPO", etc. manufactured by IGM Regins.

[0207] In some embodiments, as the photoinitiator, a photoinitiator that is not easily decomposed or generates free radicals by heating is preferably used. For example, as the photoinitiator, a heat-resistant photoinitiator with a 10% weight loss temperature of 200 °C or higher can be used. By using such a heat-resistant photoinitiator, even if it is exposed to high temperatures before the curing treatment, it is not easily damaged by the decrease in the peel strength brought about by the curing treatment based on active energy rays. It should be noted that the 10% weight loss temperature refers to the environmental temperature at the time when the photoinitiator is placed in a nitrogen atmosphere and the environmental temperature is raised from 23 °C to 300 °C at a heating rate of 2 °C / min, and the weight of the photoinitiator is reduced by 10% relative to the weight before heating (i.e., the weight of the photoinitiator becomes 90% of the weight before heating). The 10% weight loss temperature of the photoinitiator is more preferably 210 °C or higher, and further preferably 220 °C or higher. Examples of photoinitiators with a 10% weight loss temperature in such a range include products with the trade names "Omnirad 369", "Omnirad 127", "Omnirad 379", "Omnirad 819" manufactured by IGM Regins; products with the trade name "Irgacure OXE02" manufactured by BASF Japan; products with the trade names "Esacur one", "Esacur 1001m" manufactured by Lamberti; products with the trade names "ADEKA OPTOMER N-1414", "ADEKA OPTOMER N-1606", "ADEKA OPTOMER N-1717" manufactured by Asahi Denka Kogyo Co., Ltd., etc.

[0208] The adhesive layer containing the photoinitiator can be formed using an adhesive composition containing the photoinitiator. The method of incorporating the photoinitiator into the adhesive composition is not particularly limited. For example, the photoinitiator is added to the adhesive composition, typically a liquid containing a polymer (a polymer that has completed polymerization), and mixed. In this method, the photoinitiator can be added to the composition together with other additive components (such as crosslinking agents, etc.). As another method, a method of adding a polymerization initiator that can function as a photoinitiator during polymer polymerization can be cited. In this method, the polymerization initiator can be added in such a way that a predetermined amount remains after polymerization. The residual amount of the polymerization initiator (the amount of the photoinitiator present) can be adjusted not only by the amount of the polymerization initiator added, but also by the polymer polymerization conditions, the drying conditions during the formation of the adhesive layer, the curing conditions, etc.

[0209] When the adhesive layer contains a photoinitiator, the content of the photoinitiator in the adhesive layer is not particularly limited and can be set in a manner that can appropriately exhibit the desired effects. In some embodiments, regarding the content of the photoinitiator, based on 100 parts by weight of the base polymer of the adhesive layer, it can be, for example, about 0.05 parts by weight or more, preferably about 0.1 parts by weight or more, and more preferably about 0.5 parts by weight or more. By increasing the content of the photoinitiator, the active energy ray curability of the adhesive layer is improved. In some embodiments, the content of the photoinitiator based on 100 parts by weight of the base polymer can be, for example, about 0.8 parts by weight or more, can be about 2.0 parts by weight or more, and can be about 2.5 parts by weight or more. Additionally, the content of the photoinitiator based on 100 parts by weight of the base polymer can be, for example, about 20 parts by weight or less, and generally, it is preferably about 10 parts by weight or less, more preferably about 8 parts by weight or less, can be about 6 parts by weight or less, and can be about 4 parts by weight or less. When the content of the photoinitiator is not excessive, it is preferred from the viewpoint of the storage stability of the adhesive layer of the adhesive sheet (for example, the property of suppressing performance changes caused by storing the adhesive sheet before use).

[0210] <Formation of the Adhesive Layer>

[0211] The adhesive layer (preferably a UV curable adhesive layer) constituting the adhesive surface of the adhesive sheet disclosed in this specification can be an adhesive layer formed from an adhesive composition containing a base polymer (for example, an acrylic polymer) and optionally other components as needed. The above adhesive composition can be in the following various forms: a solvent-based adhesive composition in the form of containing an adhesive (adhesive component) in an organic solvent; an active energy ray curable adhesive composition prepared in such a way that it is cured by active energy rays such as ultraviolet rays and radiation to form an adhesive; a water-dispersed adhesive composition in the form of an adhesive dispersed in water; a hot-melt adhesive composition that is coated in a heated molten state and forms an adhesive when cooled to near room temperature; and so on. It should be noted that the above active energy ray curable adhesive composition is typically a liquid composition that exhibits a fluidity that can be coated at normal temperature (about 0 °C to 40 °C, for example, around 25 °C) and is cured by irradiation with active energy rays to form an adhesive (viscoelastic body).

[0212] Some embodiments of the adhesive sheet may have a structure with an adhesive layer formed using a solvent-based adhesive composition or an active energy ray curable adhesive composition. As the adhesive composition for forming the active energy ray curable adhesive layer, a solvent-based adhesive composition can be preferably used from the viewpoints of ease of controlling the active energy ray curability and the like.

[0213] The adhesive layer of the adhesive sheet disclosed in this specification can be formed by applying (e.g., coating) an adhesive composition to a suitable surface and then appropriately performing a curing treatment (drying, crosslinking, polymerization, etc.). When two or more curing treatments are performed, they can be carried out simultaneously or in multiple steps. An adhesive layer having a multi-layer structure of two or more layers can be produced by laminating pre-formed adhesive layers. Alternatively, an adhesive composition can be coated on a pre-formed first adhesive layer and the adhesive composition can be cured to form a second adhesive layer.

[0214] Coating of the adhesive composition can be carried out, for example, using conventional coating machines such as a gravure roll coater, a reverse roll coater, a kiss roll coater, an impregnating roll coater, a bar coater, a knife coater, a spray coater, etc. For an adhesive sheet having a form with a support, as a method of providing an adhesive layer on the support, a direct method of directly applying the adhesive composition to the support to form an adhesive layer can be used, or a transfer method of transferring the adhesive layer formed on a release surface to the support can be used.

[0215] In the adhesive sheet disclosed in this specification, the thickness of the adhesive layer is not particularly limited and can be appropriately selected according to the purpose. Generally, the thickness of the adhesive layer is preferably about 5 to 200 μm, and from the viewpoint of adhesion and the like, it is preferably about 10 μm or more (e.g., 15 μm or more), can be 25 μm or more, and further preferably 150 μm or less, more preferably 100 μm or less, and still more preferably 80 μm or less (e.g., 60 μm or less, typically 40 μm or less), and can be 35 μm or less or less than 30 μm. When the adhesive sheet disclosed in this specification is a double-sided adhesive sheet having adhesive layers on both sides of a substrate, the thicknesses of the respective adhesive layers can be the same or different.

[0216] <Additional Adhesive Layer>

[0217] In some embodiments of the adhesive sheet disclosed in this specification, the adhesive sheet may have a structure in which an additional adhesive layer is laminated on the back side (the side opposite to the adhesive surface) of the adhesive layer constituting the adhesive surface. The adhesive layer constituting the adhesive surface and the additional adhesive layer are preferably laminated in direct contact. That is, it is preferable that there is no separator layer (for example, a resin film such as a polyester film) that completely separates the two adhesive layers between the adhesive layer constituting the adhesive surface and the additional adhesive layer. The additional adhesive layer may be, for example, an adhesive layer composed of one or more adhesives selected from various known adhesives such as acrylic adhesives, rubber adhesives (natural rubber-based, synthetic rubber-based, their mixed systems, etc.), silicone adhesives, polyester adhesives, urethane adhesives, polyether adhesives, polyamide adhesives, and fluorine adhesives. From the viewpoints of transparency, weather resistance, etc., in some embodiments, an acrylic adhesive may be preferably used as the constituent material of the additional adhesive layer. Regarding other matters of the additional adhesive layer, the same constitution as the above-mentioned adhesive layer may be adopted, or an appropriate constitution may be adopted based on known or conventional techniques and common general knowledge according to the use and purpose. Therefore, detailed descriptions are omitted here.

[0218] <Substrate>

[0219] In a single-sided adhesive type or double-sided adhesive type adhesive sheet with a substrate, as the substrate that supports (lines) the adhesive layer, various sheet-like substrates such as a resin film, paper, cloth, rubber sheet, foam sheet, metal foil, and their composites can be used, for example. The above-mentioned substrate may be a single layer or a laminate of the same or different substrates. It should be noted that in this specification, a single layer means a layer formed of the same composition, including a layer formed by laminating multiple layers formed of the same composition.

[0220] In a preferred embodiment, a substrate mainly composed of a resin sheet (resin film substrate) can be used. Examples of the resin constituting the substrate include polyolefin resins such as low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, ultra-low-density polyethylene, random copolymer polypropylene, block copolymer polypropylene, homopolypropylene, polybutene, polymethylpentene, ethylene-vinyl acetate copolymer (EVA), ionomer, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylate (random, alternating) copolymer, ethylene-butene copolymer, and ethylene-hexene copolymer; polyurethane; polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate, and polybutylene terephthalate (PBT); polycarbonate; polyimide; polyetheretherketone; polyetherimide; polyamides such as aromatic polyamide and wholly aromatic polyamide; polyphenylene sulfide; fluororesin; polyvinyl chloride; polyvinylidene chloride; cellulose resin; polysiloxane resin; and the like. The above resins can be used alone or in combination of two or more for forming the whole or a part of the substrate (for example, any layer in a substrate having a two-layer or more laminated structure). When the adhesive layer constituting the adhesive surface is an active energy ray curable adhesive layer, the substrate preferably has active energy ray transmissibility. In some embodiments, a substrate having an ultraviolet transmittance of 40% to 100% (more preferably 60% to 100%) at a wavelength of 365 nm can be preferably used. When using a substrate with high transmissibility, the adhesive layer can be easily cured.

[0221] As needed, various additives such as fillers (inorganic fillers, organic fillers, etc.), anti-aging agents, antioxidants, ultraviolet absorbers, antistatic agents, lubricants, plasticizers, colorants (pigments, dyes, etc.) can be incorporated into the substrate.

[0222] The above substrate can be manufactured by any suitable method. For example, it can be manufactured by known methods such as calendering, casting, blown extrusion, and T-die extrusion. Additionally, as needed, stretching treatment can be performed for manufacturing.

[0223] For the purposes of improving the adhesion to the adhesive layer, the retention of the adhesive layer, etc., physical treatments such as corona discharge treatment, plasma treatment, abrasive pad processing treatment, ozone exposure treatment, flame exposure treatment, high-voltage electric shock exposure treatment, ionizing radiation treatment, etc.; chemical treatments such as acid treatment, alkali treatment, chromic acid treatment, etc.; and known or conventional surface treatments such as adhesion promotion treatment based on a coating agent (primer) can be performed on the surface of the adhesive layer side of the substrate. Additionally, for the purpose of imparting antistatic ability, etc., a conductive vapor deposition layer containing a metal, alloy, their oxides, etc. can be provided on the surface of the substrate.

[0224] In some preferred embodiments, a primer layer can be provided on the side surface of the adhesive layer of the substrate. In other words, the primer layer can be disposed between the substrate and the adhesive layer. There is no particular limitation on the primer layer forming material, and one or more of urethane (polyisocyanate) resins, polyester resins, acrylic resins, polyamide resins, melamine resins, olefin resins, polystyrene resins, epoxy resins, phenolic resins, isocyanurate resins, polyvinyl acetate resins, etc. can be used. When an adhesive layer such as an acrylic-based one is provided on the resin film substrate with the primer layer in between, a polyester-based, urethane-based, or acrylic-based primer layer is preferred. When an acrylic-based adhesive layer is provided on a polyester-based substrate such as a PET film with the primer layer in between, a polyester-based primer layer is particularly preferred. The thickness of the primer layer is not particularly limited and can generally be in the range of about 0.1 μm to 10 μm (for example, 0.1 μm to 3 μm, typically 0.1 μm to 1 μm). The primer layer can be formed using known or conventional coating machines such as a gravure roll coater or a reverse roll coater.

[0225] When the adhesive sheet disclosed in this specification is a single-sided adhesive sheet having an adhesive layer provided on one side of the substrate, the non-forming surface (back surface) of the adhesive layer of the substrate can be subjected to a peeling treatment using a peeling treatment agent (back surface treatment agent). There is no particular limitation on the back surface treatment agent that can be used to form the back surface treatment layer, and known or conventional treatment agents such as polysiloxane-based back surface treatment agents, fluorine-based back surface treatment agents, and long-chain alkyl-based back surface treatment agents can be used according to the purpose and application.

[0226] The thickness of the substrate is not particularly limited and can be appropriately selected according to the purpose. Generally, it can be about 3 μm to 800 μm. From the viewpoints of the processability and operability of the adhesive sheet (for example, the workability during attachment to and peeling from the adherend), the thickness of the substrate is preferably 5 μm or more, more preferably 10 μm or more. From the viewpoint of improving the protection of the adherend, it is preferably 20 μm or more, and can be 30 μm or more, 40 μm or more. In some embodiments where more emphasis is placed on protection, the thickness of the substrate can be, for example, 55 μm or more, 75 μm or more, or 90 μm or more. On the other hand, from the viewpoints of reducing the load on the adherend during peeling from the adherend, etc., the thickness of the substrate is generally preferably 300 μm or less, more preferably 200 μm or less, and can be 150 μm or less, 125 μm or less, 80 μm or less, 60 μm or less.

[0227] The total thickness of the adhesive sheet (which may include an adhesive layer and a substrate, but does not include a release liner) disclosed in this specification is not particularly limited, and is preferably in the range of about 10 μm to 1000 μm. Considering the adhesion and operability, the total thickness of the adhesive sheet is preferably in the range of about 15 μm to 300 μm, more preferably in the range of about 20 μm to 300 μm, and may be in the range of 20 μm to 200 μm. In addition, from the viewpoint of improving the protection of the adherend, it is advantageous that the total thickness of the adhesive sheet is about 30 μm or more, preferably about 40 μm or more, more preferably about 50 μm or more (for example, 60 μm or more). In some embodiments that pay more attention to protection, the total thickness of the adhesive sheet can be greater than 65 μm, can be greater than 80 μm, and can be greater than 100 μm.

[0228] <Adhesive Sheet>

[0229] (Conventional peel force Fd a2 )

[0230] In the adhesive sheet disclosed in this specification, the conventional peel force Fd a2 (hereinafter, also referred to as "conventional peel force after heating at 175 °C / UV") is preferably 0.50 N / 20 mm or less. Thus, even when the adhesive sheet is exposed to a high temperature after being attached to the adherend, the load on the adherend can be suppressed during peeling after UV irradiation. By using the water peeling method for peeling from the adherend, the load on the adherend during peeling can be further reduced. The conventional peel force after heating at 175 °C / UV can be measured by the above method, more specifically, the method described in the examples below.

[0231] Here, the so-called conventional peel force after heating at 175 °C / UV being below a specified value means that at least one of the values obtained by the treatment step A (i.e., first performing a heat treatment, then performing UV irradiation, and then performing peeling) described in the examples below and the value obtained by the treatment step B (i.e., first performing UV irradiation, then performing a heat treatment, and then performing peeling) described in the examples below is below the above specified value. From the viewpoint of appropriately achieving both the bonding reliability in the heating process and the easy peelability when peeling from the adherend, it is preferred that at least the value obtained by treatment step A is below the above specified value. In addition, the so-called conventional peel force after heating at 175 °C / UV being above a specified value means that at least one (preferably both) of the values obtained by the treatment step A described in the examples below and the value obtained by treatment step B is above the above specified value. The same applies to the conventional peel force after heating at 200 °C / UV, the water peel force after heating at 175 °C / UV, the water peel force after heating at 200 °C / UV, the difference in conventional peel force after heating / UV, and the difference in water peel force after heating / UV described below.

[0232] In some cases, from the perspective of reducing the load on the adherend during peeling, the conventional peel strength after heating at 175 °C / UV is more preferably 0.40 N / 20 mm or less, further preferably 0.30 N / 20 mm or less, and can be 0.25 N / 20 mm or less, can be 0.20 N / 20 mm or less, and can be 0.15 N / 20 mm or less. There is no particular limitation on the lower limit of the conventional peel strength after heating at 175 °C / UV. From the perspective of easily achieving both the bonding reliability during processing, for example, it can be 0.001 N / 20 mm or more, can be 0.010 N / 20 mm or more, can be 0.050 N / 20 mm or more, or 0.10 N / 20 mm or more. The conventional peel strength after heating at 175 °C / UV can be adjusted by selecting the base polymer, selecting the type and amount of Compound A when using Compound A, selecting the type and amount of the crosslinking agent when using the crosslinking agent, and the like.

[0233] It should be noted that even for an adhesive sheet with a conventional peel strength Fd a2 higher than any of the above upper limit values, if it is a method that can be sufficiently light-peeled by water peeling (for example, if the water peel strength Fw a2 is 0.30 N / 20 mm or less), then for this adhesive sheet, it is also possible to peel after heating / UV by using the water peeling method, thereby ideally suppressing the load on the adherend and the occurrence of residual glue. Therefore, in the above method, the conventional peel strength Fd a2 of the adhesive sheet can be greater than 0.50 N / 20 mm. The conventional peel strength Fd a2 of the adhesive sheet in this method is not particularly limited, and can be, for example, 2.00 N / 20 mm or less or 1.00 N / 20 mm or less.

[0234] (The conventional peel strength Fd b2 )

[0235] The conventional peel strength Fd of the adhesive sheet disclosed in this specification b2 (hereinafter, also referred to as "the conventional peel strength after heating at 200 °C / UV".) is preferably 2.00 N / 20 mm or less. Thus, even when exposed to higher temperatures under more severe conditions, during peeling after UV irradiation, the load on the adherend can be suppressed. By using the water peeling method to peel from the adherend, the load on the adherend during peeling can be further reduced. The conventional peel strength after heating at 200 °C / UV can be measured by the above method, more specifically, the method described in the examples below.

[0236] In some cases, from the perspective of reducing the load on the adherend during peeling, the conventional peeling force after heating at 200°C / UV irradiation can be 1.50 N / 20 mm or less, 1.20 N / 20 mm or less, 1.00 N / 20 mm or less, or 0.80 N / 20 mm or less. There is no particular limitation on the lower limit of the conventional peeling force after heating at 200°C / UV irradiation. From the perspective of easily achieving joint reliability during processing, for example, it can be 0.001 N / 20 mm or more, and can be 0.050 N / 20 mm or more, 0.10 N / 20 mm or more, or 0.30 N / 20 mm or more. The conventional peeling force after heating at 200°C / UV irradiation can be adjusted by the selection of the base polymer, the selection of the type and amount of Compound A when using Compound A, the selection of the type and amount of the crosslinking agent when using the crosslinking agent, etc.

[0237] It should be noted that even for an adhesive sheet with a conventional peeling force Fd b2 higher than any of the above upper limit values, if it is a method that can be sufficiently lightly peeled by water peeling (for example, if the water peeling force Fw b2 is 1.00 N / 20 mm or less), then for this adhesive sheet, it is also possible to peel after heating / UV irradiation by using the water peeling method, thereby ideally suppressing the load on the adherend and the occurrence of residual glue. Therefore, in the above method, the conventional peeling force Fd of the adhesive sheet b2 can be greater than 2.00 N / 20 mm. The conventional peeling force Fd of the adhesive sheet in this method b2 is not particularly limited. For example, it can be 5.00 N / 20 mm or less or 3.00 N / 20 mm or less.

[0238] (The water peeling force Fw a2 )

[0239] The water peeling force Fw of the adhesive sheet disclosed in this specification a2 (hereinafter, also referred to as "the water peeling force after heating at 175°C / UV irradiation") is preferably 0.30 N / 20 mm or less. Thus, even when the adhesive sheet is exposed to a high temperature after being attached to the adherend, the load on the adherend can be suppressed during peeling after UV irradiation. The water peeling force after heating at 175°C / UV irradiation can be measured by the above method, more specifically, the method described in the examples below.

[0240] In some embodiments, from the perspective of reducing the load on the adherend during peeling, the water peel strength after heating at 175°C / UV is more preferably 0.20 N / 20 mm or less, further preferably 0.15 N / 20 mm or less, may be 0.10 N / 20 mm or less, and may be 0.05 N / 20 mm or less. There is no particular limitation on the lower limit of the water peel strength after heating at 175°C / UV. From the perspective of easily achieving both bonding reliability during processing, for example, it may be 0.001 N / 20 mm or more, may be 0.005 N / 20 mm or more, may be 0.010 N / 20 mm or more, or may be 0.020 N / 20 mm or more. The water peel strength after heating at 175°C / UV can be adjusted by selecting the base polymer, selecting the type and amount of Compound A when using Compound A, selecting the type and amount of the crosslinking agent when using the crosslinking agent, and the like.

[0241] (Water peel strength Fw b2 )

[0242] The water peel strength Fw of the adhesive sheet disclosed in this specification b2 (hereinafter, also referred to as "water peel strength after heating at 200°C / UV") is preferably 1.00 N / 20 mm or less. Thus, even when exposed to high temperatures under more severe conditions, during peeling after UV irradiation, the load on the adherend can be suppressed. The water peel strength after heating at 200°C / UV can be measured by the above method, more specifically, the method described in the examples below.

[0243] In some embodiments, from the perspective of reducing the load on the adherend during peeling, the water peel strength after heating at 200°C / UV can be 0.80 N / 20 mm or less, 0.60 N / 20 mm or less, 0.40 N / 20 mm or less, or 0.30 N / 20 mm or less. There is no particular limitation on the lower limit of the water peel strength after heating at 200°C / UV. From the perspective of easily achieving both bonding reliability during processing, for example, it may be 0.001 N / 20 mm or more, may be 0.050 N / 20 mm or more, or may be 0.10 N / 20 mm or more. The water peel strength after heating at 200°C / UV can be adjusted by selecting the base polymer, selecting the type and amount of Compound A when using Compound A, selecting the type and amount of the crosslinking agent when using the crosslinking agent, and the like.

[0244] (Conventional peel strength difference Fd b2 -Fd a2 )

[0245] The difference between the conventional peel strength after heating at 175°C / UV and the conventional peel strength after heating at 200°C / UV of the adhesive sheet disclosed in this specification (Fd b2 -Fd a2, that is, the difference in the normal peel strength after heating / UV (hereinafter also referred to as "the difference in normal peel strength after heating / UV") is preferably 1.50 N / 20 mm or less. Thus, the adhesive sheet becomes an adhesive sheet whose peel strength after the high-temperature process is not easily affected by the temperature unevenness that may occur in the above high-temperature process. For the adhesive sheet, when peeling the adhesive sheet that has undergone the high-temperature process in the state of being attached to the adherend, the risk of residual adhesive generation can be reduced, and in addition, the load on the adherend due to the variation in the peel strength can be reduced, so it is preferred. From the viewpoint of further reducing the influence of the above temperature unevenness, the difference in normal peel strength after heating / UV is more preferably 1.20 N / 20 mm or less, can be 0.90 N / 20 mm or less, and can be 0.70 N / 20 mm or less. The difference in normal peel strength after heating / UV is usually 0 N / 20 mm or more, so there is no particular limitation on the lower limit, and the closer it is to 0 N / 20 mm, the more preferred.

[0246] (Difference in water peel strength Fw b2 -Fw a2 )

[0247] The difference between the water peel strength after heating / UV at 175 °C and the water peel strength after heating / UV at 200 °C of the adhesive sheet disclosed in this specification (Fw b2 -Fw a2 ; hereinafter, also referred to as "the difference in water peel strength after heating / UV".) is preferably 1.00 N / 20 mm or less. Thus, the adhesive sheet becomes an adhesive sheet whose peel strength after the high-temperature process is not easily affected by the temperature unevenness that may occur in the above high-temperature process. The adhesive sheet is preferred from the viewpoint of reducing the load on the adherend and reducing the risk of residual adhesive generation when peeling the adhesive sheet that has undergone the high-temperature process in the state of being attached to the adherend. From the viewpoint of further reducing the influence of the above temperature unevenness, the difference in water peel strength after heating / UV is more preferably 0.90 N / 20 mm or less, further preferably 0.70 N / 20 mm or less, can be 0.50 N / 20 mm or less, and can be 0.30 N / 20 mm or less. The difference in water peel strength after heating / UV is usually 0 N / 20 mm or more, so there is no particular limitation on the lower limit, and the closer it is to 0 N / 20 mm, the more preferred.

[0248] (Initial normal peel strength Fd0)

[0249] The initial conventional peel force Fd0 of the adhesive sheet disclosed in this specification is preferably 0.10 N / 20 mm or more. Thereby, the adhesive sheet exhibits appropriate adhesiveness as an adhesive sheet for semiconductor processing, which can contribute to the improvement of processability. For example, when the adhesive sheet disclosed in this specification is used as a back grinding tape for protecting the circuit formation surface of the semiconductor wafer (adherend) in the back grinding process of the semiconductor wafer, peeling of the adhesive sheet and breakage of the semiconductor wafer during back grinding can be prevented. The initial conventional peel force Fd0 can be measured by the above method, more specifically, the method described in the examples below. From the viewpoints of adhesion to the adherend, protection during processing, etc., the initial conventional peel force Fd0 is preferably 0.20 N / 20 mm or more, more preferably 0.30 N / 20 mm or more. From the viewpoint of improving the above adhesion and protection, in some embodiments, the initial conventional peel force Fd0 can be, for example, 0.50 N / 20 mm or more, 1.00 N / 20 mm or more, 2.00 N / 20 mm or more. There is no particular limitation on the upper limit of the initial conventional peel force Fd0. From the viewpoint of easily reducing the peel force after heating / UV, the initial conventional peel force Fd0 can be, for example, 10.0 N / 20 mm or less, 8.00 N / 20 mm or less, 5.00 N / 20 mm or less, 3.50 N / 20 mm or less. In some embodiments of the adhesive sheet disclosed in this specification, the initial conventional peel force Fd0 can be, for example, 2.50 N / 20 mm or less, 2.00 N / 20 mm or less, 1.50 N / 20 mm or less, 1.00 N / 20 mm or less, or 0.50 N / 20 mm or less. The initial conventional peel force Fd0 can be adjusted by the selection of the base polymer, the selection of the type and amount of Compound A when using Compound A, the selection of the type and amount of the crosslinking agent when using the crosslinking agent, etc.

[0250] (Non-heated conventional peel force Fd U1 )

[0251] The non-heated conventional peel force Fd of the adhesive sheet disclosed in this specification U1 is preferably 0.10 N / 20 mm or less. Thereby, the adhesive sheet exhibits excellent light peelability, for example, in a semiconductor processing mode that does not involve high-temperature processes (e.g., high-temperature processes of 100 °C or more, preferably 60 °C or more), and can reduce the load applied to the adherend during peeling. Thereby, for example, for an adhesive sheet that can be used as a back grinding tape, not only can damage to the thinned semiconductor wafer by back grinding be avoided, but also the above adhesive sheet can be efficiently peeled from the semiconductor wafer. From the viewpoint of easily reducing the peel force after heating / UV, it is also preferable that the non-heated conventional peel force Fd U1 is low. The non-heated conventional peel force Fd U1It can be measured by using the above methods, more specifically, the methods described in the examples below. In some embodiments, the non-heated conventional peel force Fd U1 For example, it can be 0.080 N / 20 mm or less, 0.060 N / 20 mm or less, 0.040 N / 20 mm or less, 0.030 N / 20 mm or less, or 0.020 N / 20 mm or less. The non-heated conventional peel force Fd U1 An adhesive sheet with a low non-heated conventional peel force Fd can further reduce the peel force by water peeling, and thus is preferred. U1 There is no particular limitation on the lower limit of the non-heated conventional peel force Fd. From the perspective of reducing the load on the adherend described above, the smaller it is, the more advantageous. On the other hand, from the perspective of achieving a balance between the adhesion to the adherend and the protection during processing, in some embodiments, the non-heated conventional peel force Fd U1 For example, it can be 0.001 N / 20 mm or more. The non-heated conventional peel force Fd U1 It can be adjusted by selecting the base polymer, selecting the type and amount of compound A when using compound A, selecting the type and amount of the crosslinking agent when using the crosslinking agent, and the like.

[0252] (The non-heated water peel force Fw U1 )

[0253] The non-heated water peel force Fw of the adhesive sheet disclosed in this specification U1 is preferably 0.050 N / 20 mm or less. Thus, the adhesive sheet exhibits excellent light peelability, for example, in semiconductor processing methods that do not involve high-temperature processes (such as high-temperature processes of 100 °C or higher, preferably 60 °C or higher), and can reduce the load applied to the adherend during peeling. Thus, for an adhesive sheet that can be used as a back grinding tape, for example, it can not only avoid damaging the thinned semiconductor wafer by back grinding, but also efficiently peel the above adhesive sheet from the semiconductor wafer. From the perspective of easily reducing the peel force after heating / UV, it is also preferred that the non-heated water peel force Fw U1 is low. The non-heated water peel force Fw U1 It can be measured by using the above methods, more specifically, the methods described in the examples below. In some embodiments, the non-heated water peel force Fw U1 is preferably less than 0.030 N / 20 mm, more preferably less than 0.020 N / 20 mm, can be less than 0.010 N / 20 mm, can be less than 0.007 N / 20 mm, or less than 0.005 N / 20 mm. The non-heated water peel force Fw U1The lower limit is not particularly limited, and from the viewpoint of reducing the load on the adherend described above, the smaller it is, the more advantageous. On the other hand, from the viewpoint of achieving a balance between the adhesion to the adherend and the protection during processing, in some embodiments, the non-heated water peel strength Fw U1 For example, it can be 0.0005 N / 20 mm or more, and can be 0.001 N / 20 mm or more. The non-heated water peel strength Fw U1 can be adjusted by the selection of the base polymer, the selection of the type and amount of Compound A when using Compound A, the selection of the type and amount of the crosslinking agent when using the crosslinking agent, and the like.

[0254] As the tensile testing machine used in the measurement of the above-mentioned various conventional peel strengths and water peel strengths, a precision universal testing machine "Autograph EZ-S" manufactured by Shimadzu Corporation or a device equivalent thereto can be used. During the measurement, if necessary, an appropriate lining material (for example, a PET film with a thickness of about 25 μm) can be attached to the adhesive sheet to be measured for reinforcement.

[0255] It should be noted that in the following examples, the conventional peel strength and the water peel strength were continuously measured for each test piece, but the conventional peel strength and the water peel strength can also be measured using different test pieces. For example, when it is difficult to prepare a test piece with a length sufficient for continuous measurement, a method of measuring using different test pieces can be adopted.

[0256] In a preferred embodiment of the adhesive sheet disclosed in this specification, the ratio of the non-heated water peel strength Fw U1 [N / 20 mm] to the initial conventional peel strength Fd0 [N / 20 mm], that is, Fw U1 / Fd0 (hereinafter, also referred to as "peel strength retention rate".) For example, it can be less than 10.0%. For such an adhesive sheet, in the usage mode of being temporarily attached to the adherend during the manufacturing process of the product, at the stage where peeling is not desired, it can exhibit good adhesion and protection to the adherend, and can effectively reduce the load applied to the adherend during peeling. The above-mentioned peel strength retention rate is preferably less than 5.0%, more preferably less than 3.0%, can be less than 2.0%, can be less than 1.0%, can be less than 0.70%, less than 0.50% or less than 0.30%. Fw U1 / Fd0 has no particular limitation. From the viewpoint of reducing the load on the adherend described above, the smaller Fw U1 / Fd0 is, the more advantageous. On the other hand, from a practical viewpoint such as cost, in some adhesive sheets, Fw U1 / Fd0 can be 0.01% or more, can be 0.05% or more, can be 0.10% or more.

[0257] In some preferred embodiments of the adhesive sheet disclosed in this specification, the non-heated water peel strength Fw U1 [N / 20mm] relative to the non-heated conventional peel strength Fd U1 [N / 20mm] may have a reduction rate greater than 30%, for example. That is, the reduction rate of the water peel strength calculated by the following formula is preferably greater than 30%.

[0258] Reduction rate of water peel strength = 1 - (Fw U1 / Fd U1 )

[0259] For an adhesive sheet with a high reduction rate of water peel strength, by peeling using the water peeling method after UV irradiation, thus, compared with the case of peeling using the conventional peeling method, the peel strength is significantly reduced, and the load applied to the adherend during peeling can be effectively reduced. In the adhesive sheet related to some preferred embodiments, the reduction rate of the water peel strength can be 55% or more, 65% or more, or 75% or more. There is no particular limitation on the upper limit of the reduction rate of the water peel strength, and it is usually 100% or less. From a practical point of view, etc., for example, it can be 95% or less, and can be 90% or less.

[0260] <Usage>

[0261] The adhesive sheet disclosed in this specification can be used for the processing of various semiconductor wafers. The above-mentioned semiconductor wafers can be, for example, silicon wafers, silicon carbide (SiC) wafers, nitride semiconductor wafers (such as silicon nitride (SiN), gallium nitride (GaN), etc.), and compound semiconductor wafers such as gallium arsenide wafers. For the adhesive sheet disclosed in this specification, in the process of manufacturing semiconductor elements (for example, semiconductor chips) from such semiconductor wafers, typically, in the manner of being bonded to the above-mentioned semiconductor wafer on which a circuit has been formed through the previous process, it can be preferably used as an adhesive sheet for semiconductor processing for protecting and / or fixing the semiconductor wafer during the processing of the semiconductor wafer. Examples of the processing that can be performed on the semiconductor wafer after bonding the adhesive sheet disclosed in this specification and until the adhesive sheet is peeled off include back grinding processing and dicing processing, but are not limited to these. It should be noted that in this specification, when the shape of the semiconductor wafer as the processing object changes due to processing (for example, overall or partial thinning based on back grinding processing, single chips obtained through dicing processing, etc.), the processed article is sometimes still referred to as a semiconductor wafer.

[0262] The bonding of the adhesive sheet disclosed in this specification to the semiconductor wafer can be performed by any suitable method. The temperature during bonding the adhesive sheet can be around room temperature (e.g., 10°C to 35°C), or can be a temperature in the range higher than room temperature (e.g., higher than 35°C, preferably 60°C to 90°C). When bonding the adhesive sheet at a temperature in the range higher than room temperature, it can be advantageous from the viewpoint of improving the adhesion of the adhesive sheet to the semiconductor wafer. After bonding the adhesive sheet within the room temperature range, a heat and pressure treatment can be performed by applying a temperature in the range higher than room temperature (e.g., 40°C to 90°C, preferably 40°C to 60°C) and a pressure higher than atmospheric pressure (e.g., 1.5 to 10 atm, preferably 3 to 7 atm). The time for performing the above heat and pressure treatment is not particularly limited and can be set in a manner that can obtain a suitable treatment effect. In some embodiments, considering the balance between the stability of the treatment effect and productivity, the time for performing the above heat and pressure treatment can be set to 3 minutes to 1 hour (e.g., 5 minutes to 30 minutes).

[0263] For the adhesive sheet disclosed in this specification, by satisfying at least one of the above conditions A to D, even if it is exposed to a high temperature during the period from attachment to the adherend to peeling, it can be peeled well from the adherend subsequently, for example, it can suppress residual adhesive and the load on the adherend. Making effective use of the above advantages, the adhesive sheet disclosed in this specification can be preferably used in the following manner: a manner in which a high-temperature process is performed during the period from being bonded to the adherend until being peeled from the adherend. As a non-limiting example of the above high-temperature process, an ion implantation process for a semiconductor wafer, an ashing process for removing a resist, an annealing process such as laser annealing, etc. can be cited. Such a high-temperature process can be performed, for example, in a state where a semiconductor processing adhesive sheet (back grinding tape) used in a back grinding process is attached, before and / or after the back grinding process. Therefore, the adhesive sheet disclosed in this specification can be preferably used as a semiconductor processing adhesive sheet used in the following manner: a manner in which a back grinding process and a high-temperature process (which is performed before and / or after the back grinding process) are included between the process of bonding to the adherend and the process of peeling from the above adherend.

[0264] The adhesive sheet disclosed in this specification can be preferably used in the following manner: a manner in which active energy rays are irradiated after being bonded to the adherend and before being peeled from the adherend. The irradiation conditions of the active energy rays are not particularly limited and can be set in a manner that can appropriately cure the adhesive layer. If a person skilled in the art, based on the common general knowledge in the art, can set appropriate irradiation conditions without undue burden, so detailed description is omitted. As an example, when using UV as the active energy ray, for the UV irradiation conditions, for example, the cumulative light amount can be made about 50 mJ / cm 2 ~5000 mJ / cm2 in the range of about 50 mJ / cm 2 to 2000 mJ / cm 2 in the range of about 100 mJ / cm 2 to 2000 mJ / cm 2 in the range, the irradiation time can be in the range of about 1 second to 30 minutes.

[0265] When performing a high-temperature process and irradiation with active energy rays during the period from when the adhesive sheet disclosed in this specification is adhered to the adherend until it is peeled off from the adherend, the irradiation with the active energy rays can be performed after the high-temperature process (for example, processing step A in the examples described later), or can be performed before the high-temperature process (for example, processing step B in the examples described later). For the adhesive sheet disclosed in this specification, even after undergoing a high-temperature process, good light peelability can be achieved by irradiation with active energy rays. Therefore, it can be preferably used in a mode where active energy rays are irradiated after the high-temperature process. By the above method, there is an advantage that the bonding reliability of the adhesive sheet to the adherend is good during the high-temperature process. On the other hand, the adhesive sheet disclosed in this specification can also be preferably used in a mode where active energy rays are irradiated before the high-temperature process. By the above usage method, effects such as further reducing the peel force after the high-temperature process and further reducing the influence of processing unevenness (temperature unevenness, etc.) during the high-temperature process on the peel force can be achieved.

[0266] The peeling of the adhesive sheet disclosed in this specification from the adherend can be carried out using a conventional peeling method (that is, a peeling method that does not use an aqueous peeling liquid such as water), or can be carried out using a water peeling method. From the viewpoint of improving peelability, in some modes, the water peeling method can be preferably adopted. As the aqueous peeling liquid used in the water peeling method, a liquid obtained by containing a small amount of additives as needed in water or a mixed solvent mainly composed of water can be used. As the solvent other than water constituting the above mixed solvent, a lower alcohol (such as ethanol) or a lower ketone (such as acetone) that can be uniformly mixed with water can be used. As the above additives, known surfactants, pH regulators, etc. can be used. From the viewpoint of avoiding contamination of the adherend, in some modes, an aqueous peeling liquid substantially free of additives can be preferably used. From the viewpoint of environmental hygiene, water is particularly preferably used as the aqueous peeling liquid. There is no particular limitation on the water. Considering the purity required according to the use, availability, etc., for example, distilled water, ion-exchanged water, tap water, etc. can be used.

[0267] The adhesive sheet disclosed in this specification can be peeled from the adherend while highly suppressing the load on the adherend, for example, by using the water peeling method. Therefore, it is suitable as an adhesive sheet that can be used in a manner of peeling from the hard and brittle thin portion (hereinafter, also referred to as the hard and brittle thin portion) of the adherend made of a hard and brittle material (for example, the constituent material of the above-mentioned semiconductor wafer, various ceramic materials such as sapphire, glass, etc.). The adhesive sheet disclosed in this specification can be preferably used as an adhesive sheet temporarily attached to such an adherend, and can prevent the occurrence of cracks and damages in the above-mentioned hard and brittle thin portion due to the load when the adhesive sheet is peeled. It should be noted that the above-mentioned hard and brittle thin portion can be a portion formed by processing the adherend after the adhesive sheet is attached to the adherend.

[0268] <Semiconductor Element Manufacturing Method>

[0269] Hereinafter, an embodiment of a semiconductor element manufacturing method using the adhesive sheet disclosed in this specification will be described. The semiconductor element manufacturing method of this embodiment includes the following steps: Step (1), attaching the adhesive surface of the semiconductor processing adhesive sheet to the circuit formation surface side of the semiconductor wafer having a circuit formation surface; Step (2), performing processing on the semiconductor wafer to which the above-mentioned adhesive sheet is attached from the side opposite to the adhesive sheet; and Step (3), peeling the above-mentioned adhesive sheet from the processed semiconductor wafer.

[0270] The above-mentioned Step (3) is preferably performed by supplying an aqueous peeling liquid to the peeling front of the adhesive sheet peeled from the processed semiconductor wafer (adherend). Thereby, the adhesive sheet is lightly peeled, so that residual glue can be suppressed, and the load on the adherend (processed semiconductor wafer) can be reduced. In some embodiments, the above-mentioned Step (3) can be preferably implemented by the adhesive sheet peeling method described later.

[0271] Preferably, after the above-mentioned Step (1) and before the above-mentioned Step (3), the above-mentioned high-temperature process is performed. In addition, preferably, a treatment of irradiating the adhesive sheet with active energy rays is performed during or before the above-mentioned Step (3). Typically, the peeling force of the adhesive sheet is decreased by the above-mentioned irradiation treatment. The above-mentioned irradiation treatment can be performed during the above-mentioned Step (3), or can be performed before the above-mentioned Step (3) and before the above-mentioned high-temperature process. By peeling the adhesive sheet (preferably water peeling) after the above-mentioned irradiation treatment, the load applied to the adherend (processed semiconductor wafer) during peeling can be effectively reduced. From the viewpoint of simultaneously achieving the bonding reliability with respect to the adherend in Step (2) and the light peeling property in Step (3), the above-mentioned irradiation treatment is preferably performed after Step (2).

[0272] In some embodiments, the above-mentioned process (2) can be a back grinding process. In this case, the above-mentioned adhesive sheet can be used as a back grinding tape. The back grinding process can be carried out by any suitable method. The back grinding process can be the following process: thinning the semiconductor wafer to which the adhesive sheet is attached until the thickness of the semiconductor wafer becomes, for example, 150 μm or less, 100 μm or less, 50 μm or less, or 30 μm or less. As described above, in the method of thinning, the effect of water peeling the adhesive sheet in process (3) can be suitably exerted. It should be noted that the back grinding process can be carried out in such a way that the inside of the annular convex portion becomes a concave portion (that is, in such a way that a TAIKO (registered trademark) wafer can be obtained). In this case, the thickness of the thinned semiconductor wafer refers to the thickness of the above-mentioned concave portion. In addition, although not particularly limited, the thickness of the semiconductor wafer before back grinding can be, for example, about 500 μm to 1000 μm.

[0273] The semiconductor element manufacturing method disclosed in this specification may further include any suitable process. Examples of such arbitrary processes include, but are not limited to, an etching process, a lithography process, an ion implantation process, a cutting process, a diebonding process, a wire bonding process, a packaging process, etc. Each of the processes exemplified above can be carried out in the above-mentioned process (2), can be carried out after the above-mentioned process (2) and before the above-mentioned process (3), or can be carried out after the above-mentioned process (3).

[0274] <Adhesive Sheet Peeling Method>

[0275] According to this specification, an adhesive sheet peeling method for peeling an adhesive sheet attached to an adherend from the adherend can be provided. This method may include the following water peeling process, that is, at the peeling front edge where the adhesive sheet is peeled from the adherend, while the aqueous peeling liquid enters the interface between the adherend and the adhesive sheet while following the movement of the peeling front edge, the adhesive sheet is peeled from the adherend. Here, the so-called peeling front edge refers to the position where the adhesive surface of the adhesive sheet starts to separate from the adherend when the adhesive sheet is peeled from the adherend. Through the above water peeling process, the adhesive sheet can be effectively peeled from the adherend by using the above aqueous peeling liquid. The above peeling method can be preferably implemented, for example, in such a way as to peel any of the adhesive sheets disclosed in this specification from the adherend.

[0276] The adherend in the peeling method disclosed in this specification may be various semiconductor wafers exemplified above. The above-mentioned semiconductor wafer may be a semiconductor wafer on which a circuit is formed. The peeling method disclosed in this specification can preferably be used as a method for peeling an adhesive sheet adhered to the circuit formation surface of a semiconductor wafer on which a circuit is formed from the above-mentioned circuit formation surface. After the above-mentioned adhesive sheet is adhered to the adherend, a high-temperature process can be performed before the start of the above-mentioned water peeling.

[0277] As the adhesive sheet that can be peeled from the adherend using the above-mentioned peeling method, any of the adhesive sheets disclosed in this specification can preferably be used. Therefore, the above-mentioned peeling method is suitable as a peeling method for any of the adhesive sheets disclosed in this specification.

[0278] In some embodiments, the above-mentioned peeling method can preferably be implemented by including the following steps: at one end of the outer edge of the adhesive sheet adhered to the adherend, forcibly lift the adhesive sheet from the above-mentioned adherend, thereby forming an initial peeling front; supply an aqueous peeling liquid to the above-mentioned peeling front; and while following the movement of the above-mentioned peeling front to allow the above-mentioned aqueous peeling liquid to enter the interface between the adhesive sheet and the above-mentioned adherend, peel the above-mentioned adhesive sheet from the above-mentioned adherend. The formation of the above-mentioned initial peeling front can be carried out, for example, by the following methods: inserting the tip of a tool such as a cutter or a needle into the interface between the adhesive sheet and the adherend; grasping and lifting the above-mentioned adhesive sheet with a hook, a claw, etc.; attaching a strongly adhesive adhesive tape, a suction cup, etc. to the back surface of the adhesive sheet and lifting the end of the adhesive sheet; and so on. After forming the initial peeling front as described above and supplying an aqueous peeling liquid to the peeling front to start water peeling, the supply of the aqueous peeling liquid to the above-mentioned peeling front can be efficiently carried out. In addition, in the above-mentioned peeling method and the adhesive sheet used in the peeling method, it is ideally possible to simultaneously achieve: good water peelability after making a start of peeling by performing an operation of forcibly forming an initial peeling front; and high water resistance reliability in the case where the above-mentioned operation is not performed.

[0279] In some embodiments, the above-described peeling method may preferably be carried out as follows: after supplying an aqueous peeling liquid to the above-described initial peeling front (i.e., after supplying the aqueous peeling liquid at the start of water peeling), the adhesive sheet is peeled without supplying a new aqueous peeling liquid. Alternatively, if during water peeling, the aqueous peeling liquid that enters the interface between the adhesive sheet and the adherend following the movement of the peeling front is depleted or insufficient midway, the aqueous peeling liquid may also be intermittently or continuously supplied after the start of this water peeling. For example, in cases where, as peeling progresses, the length of the peeling front increases (e.g., in the case of water peeling along the radial direction of a circle from one end of the outer edge of a disk-shaped adherend), or in cases where it is easy for the aqueous peeling liquid to remain on the surface of the adherend, etc., a method of supplying the aqueous peeling liquid after the start of water peeling may preferably be employed. Additionally, the position where the aqueous peeling liquid is supplied may be one location or multiple locations. In the case of supplying the aqueous peeling liquid after the start of water peeling, the number of positions where the aqueous peeling liquid is supplied after the start of water peeling may be increased or decreased.

[0280] The peeling method disclosed in this specification may preferably be carried out using an adhesive sheet having an adhesive surface composed of an active energy ray-curable adhesive layer. In some preferred embodiments of the peeling method using the adhesive sheet, after the adhesive sheet is adhered to the adherend, before the start of the above-described water peeling, the adhesive sheet is irradiated with active energy rays. Thereby, the effect of reducing the peeling force based on water peeling can be exhibited particularly well.

[0281] It should be noted that the matters disclosed in this specification include the following aspects.

[0282] 〔1〕An adhesive sheet for semiconductor processing, which is an adhesive sheet for semiconductor processing including an adhesive layer constituting the adhesive surface, and its conventional peeling force Fd a2 is 0.50 N / 20 mm or less, and the conventional peeling force Fd a2 is measured by the following method A:

[0283] After attaching the above-described adhesive surface to a silicon wafer, performing a heat treatment at 175 °C for 15 minutes and an ultraviolet irradiation treatment with an accumulated light amount of 1000 mJ / cm 2 the peeling strength is measured under the conditions of a stretching speed of 300 mm / minute and a peeling angle of 180 degrees.

[0284] 〔2〕An adhesive sheet for semiconductor processing, which is an adhesive sheet for semiconductor processing including an adhesive layer constituting the adhesive surface, and its water peeling force Fw a2 is 0.30 N / 20 mm or less, and the water peeling force Fw a2 is measured by the following method B:

[0285] Attach the above-mentioned adhesive surface to a silicon wafer, perform a heat treatment at 175 °C for 15 minutes and an ultraviolet irradiation treatment with an accumulated light amount of 1000 mJ / cm 2 After that, supply water to the peeling front of the above-mentioned adhesive sheet peeled from the above-mentioned silicon wafer, and measure the peeling strength under the conditions of a stretching speed of 300 mm / minute and a peeling angle of 180 degrees.

[0286] 〔3〕An adhesive sheet for semiconductor processing, which is an adhesive sheet for semiconductor processing including an adhesive layer constituting an adhesive surface, and its conventional peeling force Fd b2 is 2.00 N / 20 mm or less, and the conventional peeling force Fd b2 is measured by the following method C:

[0287] Attach the above-mentioned adhesive surface to a silicon wafer, perform a heat treatment at 200 °C for 15 minutes and an ultraviolet irradiation treatment with an accumulated light amount of 1000 mJ / cm 2 After that, measure the peeling strength under the conditions of a stretching speed of 300 mm / minute and a peeling angle of 180 degrees.

[0288] 〔4〕An adhesive sheet for semiconductor processing, which is an adhesive sheet for semiconductor processing including an adhesive layer constituting an adhesive surface, and its water peeling force Fw b2 is 1.00 N / 20 mm or less, and the water peeling force Fw b2 is measured by the following method D:

[0289] Attach the above-mentioned adhesive surface to a silicon wafer, perform a heat treatment at 200 °C for 15 minutes and an ultraviolet irradiation treatment with an accumulated light amount of 1000 mJ / cm 2 After that, supply water to the peeling front of the above-mentioned adhesive sheet peeled from the above-mentioned silicon wafer, and measure the peeling strength under the conditions of a stretching speed of 300 mm / minute and a peeling angle of 180 degrees.

[0290] 〔5〕The adhesive sheet for semiconductor processing according to any one of the above-mentioned 〔1〕 to 〔4〕, wherein, based on the conventional peeling force Fd measured by the above-mentioned method A a2 [N / 20 mm], and the conventional peeling force Fd measured by the above-mentioned method C b2 [N / 20 mm], through the following formula: Fd b2 -Fd a2 The calculated difference in conventional peeling force is 1.50 N / 20 mm or less (preferably 0.90 N / 20 mm or less).

[0291] 〔6〕The adhesive sheet for semiconductor processing according to any one of the above-mentioned 〔1〕 to 〔5〕, wherein, based on the water peeling force Fw measured by the above-mentioned method B a2 [N / 20 mm], and the water peeling force Fw measured by the above-mentioned method Db2 [N / 20 mm], by the following formula: Fw b2 -Fw a2 The difference in water peel strength calculated is 0.10 N / 20 mm or less (preferably 0.30 N / 20 mm or less).

[0292] 〔7〕The adhesive sheet for semiconductor processing according to any one of the above 〔1〕 to 〔6〕, wherein the initial conventional peel strength Fd0 is 0.30 N / 20 mm or more, and the initial conventional peel strength Fd0 is measured by the following method E:

[0293] After attaching the above adhesive surface to a silicon wafer, the peel strength is measured under the conditions of a tensile speed of 300 mm / minute and a peel angle of 180 degrees.

[0294] 〔8〕The adhesive sheet for semiconductor processing according to any one of the above 〔1〕 to 〔7〕, wherein the non-heated conventional peel strength Fd U1 is 0.10 N / 20 mm or less, and the non-heated conventional peel strength Fd U1 is measured by the following method F:

[0295] After attaching the above adhesive surface to a silicon wafer and performing ultraviolet irradiation treatment with an accumulated light quantity of 1000 mJ / cm 2 the peel strength is measured under the conditions of a tensile speed of 300 mm / minute and a peel angle of 180 degrees.

[0296] 〔9〕The adhesive sheet for semiconductor processing according to any one of the above 〔1〕 to 〔8〕, wherein the non-heated water peel strength Fw U1 is 0.050 N / 20 mm or less, and the non-heated water peel strength Fw U1 is measured by the following method G:

[0297] After attaching the above adhesive surface to a silicon wafer and performing ultraviolet irradiation treatment with an accumulated light quantity of 1000 mJ / cm 2 water is supplied to the peel front of the above adhesive sheet peeled from the silicon wafer, and the peel strength is measured under the conditions of a tensile speed of 300 mm / minute and a peel angle of 180 degrees.

[0298] 〔10〕An adhesive sheet for semiconductor processing, which is an adhesive sheet for semiconductor processing including an adhesive layer constituting an adhesive surface, and satisfies at least one of the following conditions:

[0299] (Condition A) The conventional peel strength Fd measured by the above method A a2 is 0.50 N / 20 mm or less (preferably 0.30 N / 20 mm or less);

[0300] (Condition B) The water peel strength Fw measured by the above method Ba2 is 0.30 N / 20 mm or less (preferably 0.20 N / 20 mm or less);

[0301] (Condition C) Conventional peel strength Fd measured by the above Method C b2 is 2.00 N / 20 mm or less (preferably 1.50 N / 20 mm or less, more preferably 1.00 N / 20 mm or less); and

[0302] (Condition D) Water peel strength Fw measured by the above Method D b2 is 1.00 N / 20 mm or less (preferably 0.80 N / 20 mm or less, more preferably 0.40 N / 20 mm or less).

[0303]

[11] The adhesive sheet for semiconductor processing as described in the above

[10] , which satisfies at least the above Condition D.

[0304]

[12] The adhesive sheet for semiconductor processing as described in any one of the above [1] to

[11] , wherein the adhesive layer is an active energy ray curable adhesive layer.

[0305]

[13] The adhesive sheet for semiconductor processing as described in any one of the above [1] to

[12] , wherein the adhesive layer contains a photoinitiator.

[0306]

[14] The adhesive sheet for semiconductor processing as described in any one of the above [1] to

[13] , wherein the adhesive layer is an acrylic adhesive layer.

[0307]

[15] The adhesive sheet for semiconductor processing as described in any one of the above [1] to

[14] , wherein the adhesive layer contains at least one compound A selected from the group consisting of a surfactant and a compound having a polyoxyalkylene skeleton as a heat-resistant peeling agent.

[0308]

[16] The adhesive sheet for semiconductor processing as described in any one of the above [1] to

[15] , wherein a crosslinking agent is used in the adhesive layer.

[0309]

[17] The adhesive sheet for semiconductor processing as described in any one of the above [1] to

[16] , which includes a substrate supporting the adhesive layer.

[0310]

[19] A method for manufacturing a semiconductor element, which is a method for manufacturing a semiconductor element using the adhesive sheet for semiconductor processing as described in any one of the above [1] to

[17] , and includes the following steps:

[0311] Step (1), bonding the adhesive surface of the above adhesive sheet for semiconductor processing to the circuit formation surface side of a semiconductor wafer having a circuit formation surface;

[0312] Step (2), performing processing on the semiconductor wafer to which the above-mentioned adhesive sheet is adhered, from the side opposite to the adhesive sheet; and

[0313] Step (3), peeling the above-mentioned adhesive sheet from the processed semiconductor wafer.

[0314] 〔20〕The semiconductor element manufacturing method as described in the above-mentioned 〔19〕, wherein, during or before the above-mentioned step (3), and after the above-mentioned step (1), a treatment of irradiating the above-mentioned adhesive sheet with active energy rays is performed.

[0315] 〔21〕The semiconductor element manufacturing method as described in the above-mentioned 〔19〕 or 〔20〕, wherein, after the above-mentioned step (1) and before the above-mentioned step (3), a high-temperature process (for example, a high-temperature process of 100 °C or higher, preferably 60 °C or higher) is performed.

[0316] 〔22〕The semiconductor element manufacturing method as described in the above-mentioned 〔19〕, which further includes the following steps:

[0317] High-temperature exposure step, after the above-mentioned step (1) and before the above-mentioned step (3), performing a high-temperature process (for example, a high-temperature process of 100 °C or higher, preferably 60 °C or higher); and

[0318] Irradiation step, during or before the above-mentioned step (3), and after the above-mentioned step (1), performing a treatment of irradiating the above-mentioned adhesive sheet with active energy rays.

[0319] 〔23〕The semiconductor element manufacturing method as described in the above-mentioned 〔22〕, wherein the above-mentioned irradiation step is performed after the above-mentioned high-temperature exposure step.

[0320] 〔24〕The semiconductor element manufacturing method as described in the above-mentioned 〔22〕, wherein the above-mentioned irradiation step is performed before the above-mentioned high-temperature exposure step.

[0321] 〔25〕The semiconductor element manufacturing method as described in any one of the above-mentioned 〔19〕 to 〔24〕, wherein the above-mentioned step (3) is performed by a water peeling method.

[0322] Examples

[0323] Hereinafter, some examples related to the present invention will be described, but it is not intended to limit the present invention to the content shown in the above-mentioned examples. It should be noted that in the following description, unless otherwise specified, "parts" and "%" are based on weight.

[0324] <Evaluation method>

[0325] 1. Measurement of the initial conventional peeling force Fd0

[0326] Cut the adhesive sheet to be measured into strips with a width of 20 mm to prepare test pieces. In an environment of 23°C and 50% RH, use a hand roller to attach the adhesive surface of the above test piece to the mirror surface of a 6-inch silicon wafer (manufactured by Shin-Etsu Chemical Co., Ltd., 6-inch N<100>-100) as the adherend, and let it stand for 30 minutes to produce an evaluation sample.

[0327] Then, in an environment of 23°C and 50% RH, insert a cutter into the interface between the test piece and the adherend of the above evaluation sample, peel one end of the test piece in the length direction from the adherend, and according to "Method 1 of 10.4.1 in JIS Z0237:2009: 180° peel adhesion force relative to the test plate", specifically, at a test temperature of 23°C, use a tensile testing machine (precision universal testing machine "Autograph EZ-S" manufactured by Shimadzu Corporation) to measure the peel strength under the conditions of a tensile speed of 300 mm / minute and a peel angle of 180 degrees. The measurement of the peel strength is carried out in the manner of peeling the test piece attached to the adherend from bottom to top. Conduct 3 measurements, and take their average value as the initial conventional peel force Fd0 [N / 20 mm].

[0328] 2. Measurement of non-heated conventional peel force Fd U1 of

[0329] For the evaluation sample prepared in the same manner as the measurement of the above initial conventional peel force Fd0, in an environment of 23°C and 50% RH, from the substrate side of the adhesive sheet (the opposite side of the measured adhesive surface. Hereinafter, it is also referred to as the "back side"), irradiate ultraviolet rays under the following UV irradiation condition A. Then, in an environment of 23°C and 50% RH, insert a cutter into the interface between the test piece and the adherend of the above evaluation sample, peel one end of the test piece in the length direction from the adherend, and measure the peel strength in the same manner as the measurement of the above initial conventional peel force Fd0. Conduct 3 measurements, and take their average value as the non-heated conventional peel force Fd U1 [N / 20 mm].

[0330] (UV irradiation condition A)

[0331] UV irradiator: manufactured by Nitto Seiki Co., Ltd., product name "NEL SYSTEM UM810" (high-pressure mercury lamp light source)

[0332] Irradiation dose: illuminance is 60 mW / cm 2 , cumulative light quantity is 1000 mJ / cm 2

[0333] 3. Measurement of non-heated water peel force Fw U1 of

[0334] The above non-heated conventional peel force Fd U1 In the measurement of, during the process of peeling the test piece from the adherend, 20 μL of distilled water is supplied to the position where the test piece starts to separate from the adherend (peel front), and the peel strength after the supply of the distilled water is measured. For the measurement, the peel strength is measured successively (i.e., 3 times), and their average value is taken as the non-heated water peel force Fw U1 [N / 20mm].

[0335] 4. Measurement of Conventional Peel Force after Heating / UV

[0336] (Measurement of Conventional Peel Force Fd a2 、Fd b2 Based on Treatment Step A)

[0337] The evaluation sample prepared in the same manner as the measurement of the above initial conventional peel force Fd0 is heated under the conditions of 175 °C for 15 minutes. After heating, it is placed in a normal temperature (25 °C) environment and cooled for 30 minutes. After being placed and cooled, ultraviolet rays are irradiated under the above UV irradiation condition A, and the peel strength is measured in the same manner as the measurement of the above initial conventional peel force Fd0. The measurement is carried out 3 times, and their average value is taken as the conventional peel force Fd a2 [N / 20mm].

[0338] For the measurement of the conventional peel force Fd b2 [N / 20mm] based on Treatment Step A, except that the heating conditions are changed to 200 °C for 15 minutes, the measurement is carried out in the same manner as the measurement of the above conventional peel force Fd a2 Based on Treatment Step A

[0339] (Measurement of Conventional Peel Force Fd a2 、Fd b2 Based on Treatment Step B)

[0340] Ultraviolet rays are irradiated on the evaluation sample prepared in the same manner as the measurement of the above initial conventional peel force Fd0 through the above UV irradiation condition A. The irradiated sample is heated under the conditions of 175 °C for 15 minutes, and then placed in a normal temperature (25 °C) environment and cooled for 30 minutes. After being placed and cooled, the peel strength is measured in the same manner as the measurement of the above non-heated conventional peel force Fd U1 . The measurement is carried out 3 times, and their average value is taken as the conventional peel force Fd a2 [N / 20mm].

[0341] For the conventional peel force Fd b2For the measurement of [N / 20 mm], except that the heating conditions are changed to 200 °C for 15 minutes, it is carried out in the same manner as the measurement of the conventional peel strength Fd based on Processing Step B described above. a2 The measurement is carried out in the same manner.

[0342] 5. Measurement of the water peel strength Fw2 after heating / UV

[0343] (Measurement of the water peel strength Fw a2 、Fw b2 based on Processing Step A)

[0344] In the measurement of the conventional peel strength Fd a2 、Fd b2 after heating / UV based on Processing Step A above, during the process of peeling the test piece from the adherend, 20 μL of distilled water is supplied to the position (peeling front) where the test piece starts to separate from the adherend, and the peel strength after the supply of the distilled water is measured. For the measurement, the peel strength is measured successively (i.e., 3 times), and their average value is taken as the water peel strength Fw a2 、Fw b2 [N / 20 mm].

[0345] (Measurement of the water peel strength Fw a2 、Fw b2 based on Processing Step B)

[0346] In the measurement of the conventional peel strength Fd a2 、Fd b2 after heating / UV based on Processing Step B above, during the process of peeling the test piece from the adherend, 20 μL of distilled water is supplied to the position (peeling front) where the test piece starts to separate from the adherend, and the peel strength after the supply of the distilled water is measured. For the measurement, the peel strength is measured successively (i.e., 3 times), and their average value is taken as the water peel strength Fw a2 、Fw b2 [N / 20 mm].

[0347] <Example 1>

[0348] (Preparation of the adhesive composition)

[0349] 100 parts of 2-ethylhexyl acrylate (2EHA) as a monomer raw material, 25.5 parts of N-acryloylmorpholine (ACMO), 18.5 parts of 2-hydroxyethyl acrylate (HEA), 0.3 part of benzoyl peroxide (BPO) as a polymerization initiator, and toluene as a polymerization solvent are mixed to prepare a monomer composition.

[0350] The above monomer composition was put into a polymerization experimental apparatus equipped with a detachable lid, a separatory funnel, a thermometer, a nitrogen inlet tube, a Liebig condenser, a vacuum seal, a stirrer, and a stirring blade on a 1-L round-bottom detachable flask, and nitrogen replacement was carried out at room temperature for 6 hours while stirring. Then, under a nitrogen stream, while stirring, the temperature was maintained at 60 °C for 8 hours to carry out polymerization, and a solution of polymer Q1 was obtained. The weight-average molecular weight (Mw) of this polymer Q1 was about 900,000. The Tg calculated by the Fox equation based on the composition of the above monomer raw materials was -42.7 °C.

[0351] After cooling the above solution of polymer Q1 to room temperature, 12.3 parts of 2-isocyanatoethyl methacrylate (manufactured by Showa Denko K.K., trade name “Karenz MOI”) was added, and further 0.1 part of dibutyltin(IV) dilaurate (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and stirring was carried out at 50 °C for 24 hours in an air atmosphere. Thus, an addition reaction of the above polymer Q1 and MOI was carried out to obtain a solution of polymer P1 having a carbon-carbon double bond.

[0352] It should be noted that the amount of the above MOI used was such that the ratio (M A ) of the moles (M B ) of the hydroxyl groups (functional group A) contained in HEA used in the synthesis of polymer Q1 to the moles (M A ) of the isocyanate groups (functional group B) contained in the above MOI (M B / M

[0353] ) became about 2.0.

[0354] (Production and evaluation of adhesive sheet)

[0355] On one side of a polyethylene terephthalate (PET) film, an adhesive composition C1 was coated on the release surface of a release film R1 (manufactured by Mitsubishi Rayon Co., Ltd., MRF38) with a thickness of 38 μm, which is a release surface based on polysiloxane treatment, and dried at 140 °C for 2 minutes to form an adhesive layer with a thickness of 20 μm. The adhesive layer was laminated on the easy-to-bond surface of an easy-to-bond treated PET film (thickness: 50 μm) as a substrate, and then aged at 50 °C for 2 days to obtain the adhesive sheet according to this example. This adhesive sheet is an adhesive sheet with a substrate having an adhesive surface composed of a radiation-curable adhesive layer.

[0356] For the obtained adhesive sheet, the initial conventional peel force Fd0 and the non-heated conventional peel force Fd were measured by the above method. U1 and the non-heated water peel force Fw U1 . Further, the conventional peel force Fd a2 , Fd b2 and the water peel force Fw a2 , Fw b2 based on treatment step A were measured, and the difference in the conventional peel force after heating / UV (Fd b2 - Fd a2 ) was calculated from the obtained measured values. The results are shown in Table 1.

[0357] <Example 2>

[0358] To the solution of the above polymer P1, 0.50 part of a compound A that does not phase-separate and dissolves in ethyl acetate in the above Test I, i.e., a nonionic surfactant A1 (polyoxyethylene sorbitan monolaurate, a sorbitan fatty acid ester manufactured by Kao Corporation, trade name "Rheodol TW-L 120", the number of moles of ethylene oxide added is 20, and the HLB is 16.7), was further added as a heat-resistant release agent with respect to 100 parts of the polymer P1 in the solution. Except for the above aspect, the adhesive composition C2 was prepared in the same manner as the preparation of the adhesive composition C1. It should be noted that the nonionic surfactant A1 was used in the form of an ethyl acetate solution and added in the above amount based on the solid content. The same applies to the preparation of the following adhesive compositions C3 to C5.

[0359] Except for using the above adhesive composition C2, the adhesive sheet according to this example was obtained in the same manner as in Example 1.

[0360] For the obtained adhesive sheet, the same evaluation as in Example 1 was carried out. The results are shown in Table 1.

[0361] <Example 3>

[0362] A solution of polymer P2 having a carbon-carbon double bond was obtained in the same manner as the synthesis of the above polymer P1, except that the amount of 2-isocyanatoethyl methacrylate (manufactured by Showa Denko K.K., trade name "Karenz MOI") added to the solution of the above polymer Q1 was changed to 22.5 parts.

[0363] It should be noted that the amount of the above MOI used is such that the ratio (M A ) of the moles of hydroxyl groups (functional group A) contained in HEA used in the synthesis of polymer Q1 to the moles of isocyanate groups (functional group B) contained in the above MOI (M B ) (M A / M B ) becomes approximately 1.1.

[0364] To the solution of the above polymer P2, 0.5 part of nonionic surfactant A1, 5.0 parts of isocyanate-based crosslinking agent X1 based on the solid content, and further 1 part of photoinitiator H1 were added and mixed to prepare adhesive composition C3.

[0365] (Production and Evaluation of Adhesive Sheet)

[0366] An adhesive sheet according to this example was obtained in the same manner as the production of the adhesive sheet according to Example 1, except that the above adhesive composition C3 was used.

[0367] The obtained adhesive sheet was evaluated in the same manner as in Example 1 (Example 3A). In addition, the conventional peel force Fd a2 , Fd b2 and the water peel force Fw a2 , Fw b2 were measured, and the difference in the conventional peel force after heating / UV (Fd b2 -Fd a2 ) was calculated from the obtained measured values (Example 3B). The results are shown in Table 1. It should be noted that the initial conventional peel force Fd0, the non-heated conventional peel force Fd U1 and the non-heated water peel force Fw U1 in the column of Example 3B show the same measured values as in Example 3A.

[0368] <Example 4>

[0369] (Preparation of Adhesive Composition)

[0370] 100 parts of n-butyl acrylate (BA), 78 parts of ethyl acrylate (EA), 40 parts of HEA as monomer raw materials, 0.3 part of BPO, and toluene as a polymerization solvent were mixed to prepare a monomer composition.

[0371] The above monomer composition was put into a polymerization experimental apparatus equipped with a detachable lid, a separatory funnel, a thermometer, a nitrogen inlet tube, a Liebig condenser, a vacuum seal, a stirrer, and a stirring blade on a 1 L round-bottom detachable flask, and nitrogen replacement was carried out at room temperature for 6 hours while stirring. Then, under a nitrogen stream, while stirring, it was maintained at 60 °C for 6 hours, and further maintained at 78 °C for 1 hour to carry out polymerization, obtaining a solution of polymer Q3 (Mw about 500,000). The Tg calculated by the Fox formula based on the composition of the above monomer raw materials was -37.2 °C.

[0372] After cooling the solution of the above polymer Q3 to room temperature, 43.6 parts of 2-isocyanatoethyl methacrylate (manufactured by Showa Denko K.K., trade name “Karenz MOI”) was added, and further 0.2 part of dibutyltin(IV) dilaurate (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and stirring was carried out at 50 °C for 24 hours in an air atmosphere. Thus, an addition reaction of the above polymer Q3 and MOI was carried out to obtain a solution of polymer P3 having a carbon-carbon double bond.

[0373] It should be noted that the amount of the above MOI used was such that the ratio (M A ) of the moles (M B ) of the hydroxyl group (functional group A) contained in HEA used in the synthesis of polymer Q3 to the moles (M A ) of the isocyanate group (functional group B) contained in the above MOI (M B ) became about 1.2.

[0374] (Production and evaluation of adhesive sheet)

[0375] To the solution of the above polymer P3, 0.5 part of nonionic surfactant A1, 5.0 parts of isocyanate-based crosslinking agent X1 based on the solid content, and further 1 part of photoinitiator H1 were added and mixed to prepare adhesive composition C4.

[0376] Except that the above adhesive composition C4 was used, an adhesive sheet of this example was obtained in the same manner as the production of the adhesive sheet according to Example 1.

[0377] For the obtained adhesive sheet, the same evaluation as in Example 1 was carried out (Example 4A). In addition, the conventional peel force Fd a2 , Fd b2 and the water peel force Fw a2 , Fw b2 were measured, and the difference in the conventional peel force after heating / UV (Fd b2 -Fd a2)(Example 4B). The results are shown in Table 1. It should be noted that the initial conventional peel strength Fd0, non-heated conventional peel strength Fd U1 and non-heated water peel strength Fw U1 in the columns show the same measured values as in Example 4A.

[0378] <Example 5>

[0379] Except that the amount of the isocyanate-based crosslinking agent X1 relative to 100 parts of the polymer P3 was changed to 1.0 part based on the solid content, the adhesive composition C5 was prepared in the same manner as the adhesive composition C4. Except that the above adhesive composition C5 was used, the adhesive sheet of this example was obtained in the same manner as the production of the adhesive sheet according to Example 1.

[0380] For the obtained adhesive sheet, the same evaluation as in Example 1 was carried out. The results are shown in Table 1.

[0381] <Example 6>

[0382] Except that the nonionic surfactant A1 was not used, the adhesive composition C6 was prepared in the same manner as in Example 5. Except that the above adhesive composition C6 was used, the adhesive sheet of this example was obtained in the same manner as the production of the adhesive sheet according to Example 1.

[0383] For the obtained adhesive sheet, the same evaluation as in Example 1 was carried out. The results are shown in Table 1.

[0384] [Table 1]

[0385]

[0386] As shown in Table 1, for Examples 3 to 6 of the adhesive sheets of Examples 1 to 6 that were heat / UV-treated by Treatment Step A, compared with the adhesive sheets of Examples 1 and 2, the peel strength after high-temperature exposure was significantly suppressed. In addition, for Examples 3B and 4B that were heat / UV-treated by Treatment Step B, compared with Examples 3A and 4A that were treated by Treatment Step A, the peel strength after high-temperature exposure was lower.

[0387] The specific examples of the present invention have been described in detail above, but they are merely examples and do not limit the claims. The technologies described in the claims include the technologies obtained by various deformations and changes of the above-exemplified specific examples.

Claims

1. A bonding sheet for semiconductor processing, which is a bonding sheet for semiconductor processing including an adhesive layer constituting an adhesive surface, and the conventional peel force Fd measured by the following method a2 is 0.50 N / 20 mm or less: Attach the bonding surface to the silicon wafer, perform a heat treatment at 175 °C for 15 minutes and an ultraviolet irradiation treatment with an accumulated light quantity of 1000 mJ / cm 2 After that, measure the peel strength under the conditions of a tensile speed of 300 mm / minute and a peel angle of 180 degrees. The adhesive layer contains a polymer having a carbon-carbon double bond as a base polymer. The base polymer is a polymer obtained by chemically modifying a primary polymer copolymerized from monomers having functional group A with a compound having functional group B and a carbon-carbon double bond. The molar M of the functional group A A and the molar M of the functional group B B The molar ratio M A / M B is in the range greater than 1.0 and 1.5 or less. The adhesive layer further contains a crosslinking agent and Compound A. With respect to 100 parts by weight of the base polymer, the crosslinking agent is more than 4.0 parts by weight and 12.0 parts by weight or less, and with respect to 100 parts by weight of the base polymer, Compound A is 0.1 part by weight or more and 3 parts by weight or less. Compound A is at least one compound selected from the group consisting of a surfactant and a compound having a polyoxyalkylene skeleton.

2. A bonding sheet for semiconductor processing, which is a bonding sheet for semiconductor processing including an adhesive layer constituting a bonding surface, and the water peel strength Fw measured by the following method a2 is 0.30 N / 20 mm or less: Attach the bonding surface to the silicon wafer, perform a heat treatment at 175 °C for 15 minutes and an ultraviolet irradiation treatment with an accumulated light amount of 1000 mJ / cm 2 After that, supply water to the peeling front of the adhesive sheet peeled from the silicon wafer, and measure the peeling strength under the conditions of a stretching speed of 300 mm / minute and a peeling angle of 180 degrees. The adhesive layer contains a polymer having a carbon-carbon double bond as a base polymer. The base polymer is a polymer obtained by chemically modifying a primary polymer copolymerized from monomers having a functional group A with a compound having a functional group B and a carbon-carbon double bond, and the molar M of the functional group A A and the molar M of the functional group B B The molar ratio M A / M B is in the range of greater than 1.0 and 1.5 or less, The adhesive layer further contains a crosslinking agent and Compound A. With respect to 100 parts by weight of the base polymer, the crosslinking agent is more than 4.0 parts by weight and 12.0 parts by weight or less, and with respect to 100 parts by weight of the base polymer, Compound A is 0.1 part by weight or more and 3 parts by weight or less. Compound A is at least one compound selected from the group consisting of a surfactant and a compound having a polyoxyalkylene skeleton.

3. A bonding sheet for semiconductor processing, which is a bonding sheet for semiconductor processing including an adhesive layer constituting the bonding surface, and the conventional peel strength Fd measured by the following method b2 is 2.00 N / 20 mm or less: Attach the bonding surface to the silicon wafer, perform a heat treatment at 200 °C for 15 minutes and an ultraviolet irradiation treatment with an accumulated light quantity of 1000 mJ / cm 2 After that, measure the peel strength under the conditions of a tensile speed of 300 mm / minute and a peel angle of 180 degrees. The adhesive layer contains a polymer having a carbon-carbon double bond as a base polymer. The base polymer is a polymer obtained by chemically modifying a primary polymer copolymerized from monomers having functional group A with a compound having functional group B and a carbon-carbon double bond, and the molar M of the functional group A A and the molar M of the functional group B B The molar ratio M A / M B is in the range greater than 1.0 and 1.5 or less. The adhesive layer further contains a crosslinking agent and Compound A. With respect to 100 parts by weight of the base polymer, the crosslinking agent is more than 4.0 parts by weight and 12.0 parts by weight or less, and with respect to 100 parts by weight of the base polymer, Compound A is 0.1 part by weight or more and 3 parts by weight or less. Compound A is at least one compound selected from the group consisting of a surfactant and a compound having a polyoxyalkylene skeleton.

4. A bonding sheet for semiconductor processing, which is a bonding sheet for semiconductor processing including an adhesive layer forming a bonding surface, and the water peel strength Fw measured by the following method b2 is 1.00 N / 20 mm or less: Attach the bonding surface to the silicon wafer, perform a heat treatment at 200 °C for 15 minutes and an ultraviolet irradiation treatment with an accumulated light quantity of 1000 mJ / cm 2 After that, supply water to the peeling front of the adhesive sheet peeled from the silicon wafer, and measure the peeling strength under the conditions of a peeling speed of 300 mm / minute and a peeling angle of 180 degrees. The adhesive layer contains a polymer having a carbon-carbon double bond as a base polymer. The base polymer is a polymer obtained by chemically modifying a primary polymer copolymerized from monomers having a functional group A with a compound having a functional group B and a carbon-carbon double bond, and the molar M of the functional group A A and the molar M of the functional group B B The molar ratio M A / M B is in the range greater than 1.0 and 1.5 or less, The adhesive layer further contains a crosslinking agent and Compound A. With respect to 100 parts by weight of the base polymer, the crosslinking agent is more than 4.0 parts by weight and 12.0 parts by weight or less, and with respect to 100 parts by weight of the base polymer, Compound A is 0.1 part by weight or more and 3 parts by weight or less. Compound A is at least one compound selected from the group consisting of a surfactant and a compound having a polyoxyalkylene skeleton.

5. The adhesive sheet for semiconductor processing according to any one of claims 1 to 4, wherein, According to the conventional peel force Fd a2 [N / 20mm] and the conventional peel force Fd b2 [N / 20mm], by the following formula: Fd b2 -Fd a2 The calculated difference in the conventional peel force is 1.50 N / 20mm or less The conventional peeling force Fd a2 [N / 20mm] is measured under the conditions that the adhesive surface is attached to the silicon wafer, heat treatment is carried out at 175 °C for 15 minutes, and ultraviolet irradiation treatment with an accumulated light quantity of 1000 mJ / cm 2 is carried out, and then measured at a stretching speed of 300 mm / minute and a peeling angle of 180 degrees; The conventional peel force Fd b2 [N / 20mm] is measured by operating in the same manner as the conventional peel force Fd, except that the heat treatment at 175°C for 15 minutes is replaced by a heat treatment at 200°C for 15 minutes. a2 ​ 6. The adhesive sheet for semiconductor processing according to any one of claims 1 to 4, wherein, The initial conventional peel force Fd0 measured by the following method is 0.30 N / 20 mm or more: After attaching the adhesive surface to a silicon wafer, the peel strength is measured under the conditions of a tensile speed of 300 mm / minute and a peel angle of 180 degrees.

7. The adhesive sheet for semiconductor processing according to any one of claims 1 to 4, wherein, The non-heating conventional peel force Fd measured by the following method U1 is 0.10 N / 20 mm or less: Attach the bonding surface to the silicon wafer, and after performing ultraviolet irradiation treatment with an accumulated light quantity of 1000 mJ / cm 2 , measure the peel strength under the conditions of a tensile speed of 300 mm / minute and a peel angle of 180 degrees.

8. The adhesive sheet for semiconductor processing according to any one of claims 1 to 4, wherein, The non-heating water peel force Fw measured by the following method U1 is 0.050 N / 20 mm or less: Attach the bonding surface to a silicon wafer, and after performing ultraviolet irradiation treatment with an accumulated light quantity of 1000 mJ / cm 2 , supply water to the peeling front of the adhesive sheet peeled from the silicon wafer, and measure the peeling strength under the conditions of a stretching speed of 300 mm / minute and a peeling angle of 180 degrees.

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