Adhesive sheet

Abstract

The present invention relates to an adhesive sheet having a base layer, an adhesive layer X disposed on one side of the base layer, and an adhesive layer Y disposed on the other side of the base layer, wherein the peeling force when the adhesive layer X is peeled off at 23°C in a 180° direction at a tensile speed of 300 mm / min is A, and the peeling force when the adhesive layer Y is peeled off at 23°C in a 180° direction at a tensile speed of 300 mm / min is B, with A / B = 0.5 to 2, and the peeling force when the adhesive layer X is heated at 80°C for 5 minutes and peeled off at 80°C in a 180° direction at a tensile speed of 300 mm / min is C, and the peeling force when the adhesive layer Y is heated at 80°C for 5 minutes and peeled off at 80°C in a 180° direction at a tensile speed of 300 mm / min is D, with C / D = 0.002 to 0.2.

Description

Technical Field

[0001] Cross - reference to Related Applications This invention claims the rights and priority based on Chinese Invention Patent Application No. 202310276473.3 filed in China on March 17, 2023, and the entire disclosure thereof is incorporated herein by reference.

[0002] The present invention relates to an adhesive sheet, particularly to an adhesive sheet having excellent adhesiveness and heat - releasability, which can be easily peeled off by heating after use without causing deformation or damage to the adherend.

Background Art

[0003] Generally, an adhesive exhibits a soft solid (viscoelastic body) state in a temperature range near room temperature and has the property of easily adhering to an adherend under pressure. Utilizing such properties, adhesives are widely used in the form of adhesive sheets with a substrate having an adhesive layer provided on at least one surface of the substrate for purposes such as fixing various articles, protecting the surfaces of various articles, or decoration to obtain a desired appearance.

[0004] In applications as described above, problems such as poor adhesiveness and re - peelability of the adhesive sheet may occur. Also, when the adhesive sheet becomes unnecessary and is peeled off, the adherend may be damaged or deformed.

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention is made to solve the above - mentioned existing problems, and aims to provide an adhesive sheet having excellent normal - temperature adhesiveness and high - temperature re - peelability, which can be easily peeled off at a high temperature without causing deformation or damage to the adherend.

Means for Solving the Problems

[0006] In order to solve the above-mentioned existing problems, the inventors of the present invention conducted diligent research and found that the above problems can be solved by controlling the ratio of the peeling forces when the adhesive layers on both sides of the base material layer are peeled off at 23°C in a 180° direction at a tensile speed of 300 mm / min, and the ratio of the peeling forces when the adhesive layers are heated at 80°C for 5 minutes and peeled off at 80°C in a 180° direction at a tensile speed of 300 mm / min, to a specific range, thereby completing the present invention.

[0007] In other words, the present invention is as follows. [1] An adhesive sheet having a base layer, an adhesive layer X disposed on one side of the base layer, and an adhesive layer Y disposed on the other side of the base layer, Let A be the peeling force when the adhesive layer X is peeled off at 23°C in a 180° direction at a tensile speed of 300 mm / min, and let B be the peeling force when the adhesive layer Y is peeled off at 23°C in a 180° direction at a tensile speed of 300 mm / min, where A / B = 0.5 to 2. An adhesive sheet in which the adhesive layer X is heated at 80°C for 5 minutes and peeled off at 80°C in a 180° direction at a tensile speed of 300 mm / min, and the adhesive layer Y is heated at 80°C for 5 minutes and peeled off at 80°C in a 180° direction at a tensile speed of 300 mm / min, wherein the ratio C / D = 0.002 to 0.2. [2] The adhesive sheet according to [1], wherein the peel force when the adhesive layer X is peeled off at 23°C in a 180° direction at a tensile speed of 300 mm / min is 2 to 40 N / 20 mm, and the peel force when the adhesive layer X is heated at 80°C for 5 minutes and peeled off at 80°C in a 180° direction at a tensile speed of 300 mm / min is 0.01 to 4 N / 20 mm. [3] The adhesive sheet according to [1], wherein the peel force when the adhesive layer Y is peeled off at 23°C in a 180° direction at a tensile speed of 300 mm / min is 4 to 40 N / 20 mm, and the peel force when the adhesive layer Y is heated at 80°C for 5 minutes and peeled off at 80°C in a 180° direction at a tensile speed of 300 mm / min is 5 to 40 N / 20 mm. [4] The adhesive sheet according to any one of [1] to [3], wherein the adhesive layer X comprises rubber and a tackifying resin, and the content of the tackifying resin is 5 to 120 parts by weight per 100 parts by weight of the rubber. [5] The adhesive sheet according to [4], wherein the rubber is one or more selected from styrene-ethylene-butylene-styrene rubber, styrene-butadiene-styrene rubber, styrene-butadiene rubber, and styrene-isoprene-styrene rubber. [6] The adhesive sheet according to [4], wherein the styrene content in the rubber is 5 to 25% by weight. [7] The tackifying resin is one or more selected from rosin resin, modified rosin resin, terpene resin, and C5 / C9 tackifying resin, and the tackifying resin has a softening point of 50 to 85°C or a viscosity of 1,000 to 20,000 cP at 23°C, as described in [4]. [8] The adhesive sheet according to any one of the following [1] to [3], wherein the adhesive layer Y comprises an acrylic polymer and the storage modulus G' of the adhesive layer Y at 25°C is 35 kPa to 500 kPa. [9] The base material layer has a foaming ratio of 1.1 to 20 cm 3 An adhesive sheet according to any one of the following [1] to [3], wherein the density is / g, the thickness is 0.06 to 2.0 mm, the 50% compressive strength is 100 kPa to 10000 kPa, and the thickness of the adhesive layer X and the adhesive layer Y is 1 to 200 μm each. [Effects of the Invention]

[0008] The adhesive sheet according to the present invention has excellent adhesive properties and heat-removable properties, and can be easily peeled off by heating after use without causing deformation or damage to the adherend. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic cross-sectional view showing the structure of an adhesive sheet according to one embodiment of the present invention. [Explanation of symbols]

[0010] 1 Adhesive sheet 10 Base material layer 20 Adhesive layer 30 Adhesive layer Y [Modes for carrying out the invention]

[0011] Preferred embodiments of the present invention will be described below. Matters necessary for carrying out the present invention other than those specifically mentioned herein will be understood by those skilled in the art based on the teachings on carrying out the invention described herein and the common technical knowledge at the time of filing. The present invention can be carried out based on the contents disclosed herein and the common technical knowledge in the art.

[0012] Furthermore, in the following drawings, components and parts that perform the same function may be denoted by the same reference numeral and described accordingly, and redundant explanations may be omitted or simplified. Also, the embodiments shown in the drawings are schematic for the purpose of clearly illustrating the present invention and do not necessarily accurately represent the size or scale of the actual product provided.

[0013] <Adhesive sheet> The adhesive sheet of the present invention comprises a base layer, an adhesive layer X disposed on one side of the base layer, and an adhesive layer Y disposed on the other side of the base layer. Let A be the peeling force when the adhesive layer X is peeled off at 23°C in a 180° direction at a tensile speed of 300 mm / min, and let B be the peeling force when the adhesive layer Y is peeled off at 23°C in a 180° direction at a tensile speed of 300 mm / min, where A / B = 0.5 to 2. Let C be the peeling force when the adhesive layer X is heated at 80°C for 5 minutes and peeled off at a tensile speed of 300 mm / min in a 180° direction at 80°C, and let D be the peeling force when the adhesive layer Y is heated at 80°C for 5 minutes and peeled off at a tensile speed of 300 mm / min in a 180° direction at 80°C, with C / D = 0.002 to 0.2.

[0014] Preferably, A / B = 0.6 to 1.8, more preferably 0.7 to 1.6, even more preferably 0.8 to 1.4, and even more preferably 0.9 to 1.2.

[0015] Preferably, C / D is 0.004 to 0.18, more preferably 0.006 to 0.16, still more preferably 0.008 to 0.14, and even more preferably 0.01 to 0.12.

[0016] In the present invention, by controlling the numerical values calculated by A / B and C / D within the above ranges, an adhesive sheet having excellent adhesiveness and heat releasability, which can be easily peeled off by heating after use and does not cause deformation or damage to the adherend, can be obtained.

[0017] FIG. 1 is a cross-sectional view schematically showing the structure of an adhesive sheet according to an embodiment of the present invention. As shown in FIG. 1, the adhesive sheet 1 includes a base material layer 10, an adhesive layer 20 disposed on one side of the base material layer 10, and an adhesive layer 30 disposed on the other side of the base material layer 10. The adhesive layer 20 and the adhesive layer 30 are preferably provided on the entire surface of the base material layer 10.

[0018] In the adhesive sheet of the present invention, the positions of the adhesive layer X and the adhesive layer Y (that is, the adhesive layer 20 and the adhesive layer 30) are not limited to the positions shown in FIG. 1 as long as they are disposed on both sides of the base material layer, and can be interchanged.

[0019] Although not shown, before being used, the adhesive sheet of the present invention may be provided with a release liner outside the adhesive layer for the purpose of protecting the adhesive surface.

[0020] The concept of the adhesive sheet in this specification may include those referred to as adhesive tapes, adhesive labels, adhesive films, etc. The adhesive sheet disclosed in this specification may be in a single sheet form or may be an adhesive sheet processed into various shapes. In some preferred embodiments, the adhesive sheet of the present invention may be provided in a long strip shape.

[0021] [Adhesive layer X] The adhesive layer X of the present invention has a peel force of 2 to 40 N / 20 mm when peeled at 23°C in a 180° direction at a tensile speed of 300 mm / min. The lower limit is preferably 5 N / 20 mm, more preferably 7 N / 20 mm, even more preferably 8 N / 20 mm, and even more preferably 9 N / 20 mm, and the upper limit is preferably 35 N / 20 mm, more preferably 30 N / 20 mm, even more preferably 20 N / 20 mm, and even more preferably 16 N / 20 mm.

[0022] The adhesive layer X of the present invention has a peel force of 0.01 to 4 N / 20 mm when heated at 80°C for 5 minutes and peeled off at a tensile speed of 300 mm / min in a 180° direction at 80°C. The lower limit is preferably 0.05 N / 20 mm, more preferably 0.5 N / 20 mm, even more preferably 1 N / 20 mm, and even more preferably 1.5 N / 20 mm, and the upper limit is preferably 3.5 N / 20 mm, more preferably 3 N / 20 mm, even more preferably 2.5 N / 20 mm, and even more preferably 2 N / 20 mm.

[0023] If the peeling force of the adhesive layer X at 23°C and the peeling force when heated at 80°C for 5 minutes are both within the above ranges, the adhesive sheet will have excellent tackiness and heat-removable properties, and can be easily peeled off by heating after use without causing deformation or damage to the adherend.

[0024] The above peeling force can be measured, for example, by the method described in the examples below.

[0025] The adhesive layer X of the present invention comprises rubber and a tackifying resin. The content of the tackifying resin is 5 to 120 parts by weight, preferably 10 to 100 parts by weight, more preferably 20 to 80 parts by weight, and even more preferably 30 to 50 parts by weight, per 100 parts by weight of rubber.

[0026] By setting the content of the tackifying resin within the above range, an adhesive sheet can be made that has excellent tackiness and heat-removable properties, can be easily removed by heating after use, and does not deform or damage the adherend.

[0027] The adhesive layer X in the technology disclosed herein may be a layer formed from an adhesive composition X comprising rubber and a tackifying resin. The form of the adhesive composition X is not particularly limited and may be various forms of adhesive compositions, such as water-dispersible, solvent-based, hot-melt, or active energy ray-curable (e.g., photocurable).

[0028] The components of the adhesive composition X of the present invention will be described in detail below.

[0029] (rubber) The adhesive composition X of the present invention contains rubber. The rubber can be one or more selected from styrene-ethylene-butylene-styrene rubber (SEBS), styrene-butadiene-styrene rubber (SBS), styrene-butadiene rubber (SB), and styrene-isoprene-styrene rubber (SIS). From the viewpoint of the adhesive sheet having excellent tackiness and re-peelability, and being easily peeled off after use without causing contamination by adhesive residue, one or more selected from styrene-ethylene-butylene-styrene rubber (SEBS) and styrene-isoprene-styrene rubber (SIS) are preferred. Commercially available rubbers can be used as the rubber of the present invention.

[0030] The weight-average molecular weight of the rubber is not particularly limited, but is preferably 50,000 to 500,000, and more preferably 100,000 to 300,000. This range is preferable because it tends to improve the rubber's cohesiveness, tackiness, and peel strength.

[0031] In this specification, weight-average molecular weight refers to the weight-average molecular weight calculated for the region of the molecular weight distribution curve obtained by GPC measurement in which the molecular weight in terms of polystyrene is 10,000 or more.

[0032] In the present invention, the styrene content in the rubber is 5 to 25% by weight, more preferably 8 to 24% by weight, even more preferably 10 to 15% by weight, and even more preferably 12 to 14% by weight. By setting the styrene content in the rubber within the above range, it is possible to maintain the cohesive force provided by the styrene portion while ensuring viscoelasticity provided by the soft segments. This results in an adhesive sheet that has excellent tackiness and re-peelability, and can be easily peeled off by heating after use without causing deformation or damage to the adherend.

[0033] In this specification, "styrene content" in rubber refers to the weight ratio of the styrene component to the total weight of the rubber. The styrene content can be measured by NMR (nuclear magnetic resonance spectroscopy).

[0034] (Adhesive-granting resin) In the present invention, the tackifying resin is one or more selected from rosin resin, modified rosin resin, terpene resin, and C5 / C9 tackifying resin, and the tackifying resin has a softening point of 50 to 85°C or a viscosity of 1000 to 20000 cP at 23°C.

[0035] In the present invention, by having the softening point or viscosity of the tackifying resin within the above range, the cohesive force of the adhesive layer can be increased, thereby the adhesive sheet has excellent tackiness and heat-removable properties, and can be easily peeled off by heating after use without causing deformation or damage to the adherend.

[0036] The modified rosin resin is a modified rosin resin obtained by modifying rosin resin (phenol modification, styrene modification, hydrogenation modification, hydrocarbon modification, acid modification, etc.).

[0037] The terpene resins are not particularly limited and include, for example, terpene resins; and modified terpene resins obtained by modifying these terpene resins (phenol modification, styrene modification, hydrogenation modification, hydrocarbon modification, etc.).

[0038] Examples include α-pinene polymers, β-pinene polymers, diterpene polymers, terpene phenol resins, styrene-modified terpene resins, aromatic-modified terpene resins, and hydrogenated terpene resins.

[0039] A commercially available product can be used as the tackifying resin of the present invention.

[0040] In this specification, the softening point of the tackifying resin is defined as the value measured based on the softening point test method (ring-ball method) specified in JIS K5902 and JIS K2207. The viscosity can be measured by a conventional viscosity measurement method.

[0041] (Antistatic agent) In the present invention, it is preferable that the adhesive composition X further contains an antistatic agent.

[0042] Examples of antistatic agents included in the above-mentioned adhesive layer-forming composition X include conductive polymers, conductive inorganic fine particles, metal fine particles or fibers, ionic compounds, and ionic surfactants. These antistatic agents may be used individually or in combination of two or more.

[0043] <Conductive polymer> Examples of the conductive polymers mentioned above include polyaniline, polypyrrole, polythiophene, polyquinoxaline, polyacetylene, polyethyleneimine, and allylamine polymers. Among these, polyaniline, polythiophene, and others that readily form water-soluble or water-dispersible conductive polymers are preferred. These conductive polymers may be used individually or in combination of two or more.

[0044] <Conductive inorganic particles> Examples of the above-mentioned conductive inorganic fine particles include conductive metal oxides, carbon nanotubes, graphene, fullerenes, acetylene black, Ketjenblack, natural graphite, artificial graphite, and titanium black. These conductive inorganic fine particles may be used individually or in mixtures of two or more types.

[0045] Examples of conductive metal oxides include tin oxide-based, antimony oxide-based, indium oxide-based, and zinc oxide-based metal oxides. Examples of tin oxide-based conductive fine particles include tin oxide, as well as antimony-doped tin oxide, indium-doped tin oxide, aluminum-doped tin oxide, tungsten-doped tin oxide, titanium oxide-cerium oxide-tin oxide composite, and titanium oxide-tin oxide composite. The average particle size of the fine particles is 1 to 100 nm, preferably 2 to 50 nm.

[0046] <Metal particles or fibers> Any suitable polymer can be used as the metal nanoparticles or fibers mentioned above, as long as the effects of the present invention are obtained. Examples include nanoparticles or nanowires made of gold, silver, copper, aluminum, nickel, or alloys thereof. These metal nanoparticles or fibers can be used individually or in mixtures of two or more types.

[0047] <Ionic compounds> Examples of ionic compounds include alkali metal salts and / or organic cation-anionic salts. In this invention, "organic cation-anionic salt" refers to an organic salt in which the cation portion is composed of organic matter, while the anion portion may be organic or inorganic. "Organic cation-anionic salts" are also called ionic liquids and ionic solids. These ionic compounds can be used individually or in mixtures of two or more. As alkali metal salts, organic and inorganic salts of alkali metals can be used.

[0048] <Ionic surfactants> Examples of the above-mentioned ionic surfactants include cationic surfactants (e.g., quaternary ammonium salt type, phosphonium salt type, sulfonium salt type, etc.), anionic surfactants (e.g., carboxylic acid type, sulfonate type, sulfate type, phosphate type, phosphite type, etc.), amphoteric surfactants (e.g., sulfobetaine type, alkylbetaine type, alkylimidazolium betaine type, etc.), and nonionic surfactants (e.g., polyol derivatives, β-cyclodextrin inclusion compounds, sorbitan fatty acid monoesters / diesters, polyoxyalkylene derivatives, amine oxides, etc.). These ionic surfactants may be used individually or in combination of two or more types.

[0049] In some preferred embodiments, the content of the antistatic agent is preferably 0.01 to 15 parts by weight, more preferably 0.02 to 10 parts by weight, per 100 parts by weight of the rubber. In some preferred embodiments, the content of the antistatic agent is preferably 0.01 parts by weight, 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, 1 part by weight, 5 parts by weight, 10 parts by weight, or 15 parts by weight, per 100 parts by weight of the rubber. When the content of the antistatic agent is within the above range, a sufficient antistatic effect can be obtained, the static electricity generated during peeling can be sufficiently suppressed, and damage to the adherend can be avoided or reduced.

[0050] In addition to the above components, the adhesive composition X of the present invention may optionally contain various additives commonly used in the field of adhesives, such as photoinitiators, plasticizers, softeners, anti-aging agents, and antioxidants, to the extent that they do not impair the effects of the present invention. Conventional known additives can be used in the usual manner.

[0051] (Formation of adhesive layer X) The adhesive layer X disclosed herein can be formed by conventionally known methods. For example, a direct method can be employed in which an adhesive layer is formed by directly applying (typically coating) an adhesive composition to a substrate layer and drying it. Alternatively, a transfer method can be employed in which an adhesive layer is formed on a peelable surface (release surface) by applying the adhesive composition X and drying it, and then transferring the adhesive layer to the substrate layer. From the viewpoint of productivity, the transfer method is preferred. The release surface can be the surface of a release liner, the back surface of a peeled substrate layer, etc. The adhesive layer X disclosed herein is typically formed continuously, but is not limited to this form, and may be formed in a regular or irregular pattern such as dots or stripes.

[0052] The adhesive composition X can be applied using conventionally known coaters such as gravure roll coaters, die coaters, and bar coaters. Alternatively, the adhesive composition can be applied by impregnation or curtain coating methods.

[0053] From the viewpoint of improving manufacturing efficiency, it is preferable to dry the adhesive composition X under heating. The drying temperature can be around 40 to 150°C, and is usually preferably around 60 to 130°C. After drying the adhesive composition, further aging can be performed for purposes such as adjusting the migration of components in the adhesive layer, promoting the crosslinking reaction, and alleviating any strain that may be present in the substrate film or adhesive layer.

[0054] The thickness of the adhesive layer X is not particularly limited, but considering the balance between adhesion to the adherend and cohesiveness, the thickness of the adhesive layer X is preferably 1 to 200 μm, more preferably 10 to 150 μm, even more preferably 30 to 100 μm, and even more preferably 40 to 80 μm. By setting the thickness of the adhesive layer X within the above range, good adhesion can be obtained.

[0055] [Adhesive layer Y] The adhesive layer Y of the present invention has a peel force of 4 to 40 N / 20 mm when peeled at 23°C in a 180° direction at a tensile speed of 300 mm / min. The lower limit is preferably 7 N / 20 mm, more preferably 9 N / 20 mm, even more preferably 11 N / 20 mm, and even more preferably 13 N / 20 mm, and the upper limit is preferably 35 N / 20 mm, more preferably 30 N / 20 mm, even more preferably 25 N / 20 mm, and even more preferably 20 N / 20 mm.

[0056] The adhesive layer Y of the present invention has a peeling force of 5 to 40 N / 20 mm when heated at 80°C for 5 minutes and peeled off at 80°C in a 180° direction at a tensile speed of 300 mm / min. The lower limit is preferably 7 N / 20 mm, more preferably 9 N / 20 mm, even more preferably 11 N / 20 mm, and even more preferably 13 N / 20 mm, and the upper limit is preferably 35 N / 20 mm, more preferably 25 N / 20 mm, even more preferably 15 N / 20 mm, and even more preferably 10 N / 20 mm.

[0057] If the peeling force of the adhesive layer Y of the present invention at 23°C and the peeling force when heated at 80°C for 5 minutes are both within the above ranges, an adhesive sheet with excellent tackiness can be obtained.

[0058] The above peeling force can be measured, for example, by the method described in the examples below.

[0059] The adhesive layer Y of the present invention contains an acrylic polymer. The storage modulus G' of the adhesive layer Y is 35 kPa to 500 kPa at 25°C. The storage modulus G' can be measured, for example, by the method described in the examples below.

[0060] By setting G' of the adhesive layer Y to the above range, an adhesive sheet with excellent tackiness can be obtained.

[0061] The adhesive layer Y in the technology disclosed herein may be a layer formed from an adhesive composition Y comprising an acrylic polymer. The form of the adhesive composition Y is not particularly limited and may be various forms of adhesive compositions, such as water-dispersible, solvent-based, hot-melt, or active-energy ray-curable (e.g., photocurable).

[0062] The components of the adhesive composition Y of the present invention will be described in detail below.

[0063] (Base polymer) The adhesive composition of the present invention contains an acrylic polymer as a base polymer.

[0064] The base polymer content is not particularly limited, but from the viewpoint of obtaining sufficient adhesive reliability, it is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, based on the total amount (total mass, 100% by mass) of the adhesive composition Y. By adjusting the base polymer content in the adhesive composition Y to the above range, an adhesive composition with superior stress relaxation and durability, as well as superior adhesion to the adherend, can be provided.

[0065] The base polymer in the technology disclosed herein is preferably a polymer of the following monomer components. The monomer components include a soft monomer (adhesive monomer) as the main monomer, a functional monomer (copolymerizable monomer) copolymerizable with the main monomer, and a hard monomer. Here, the main monomer refers to the main component of the monomer components constituting the base polymer (i.e., the component that makes up more than 50% by weight of the monomer component).

[0066] In one preferred embodiment, the soft monomer (sticky monomer) comprises an alkyl (meth)acrylate. In this specification, the term "alkyl (meth)acrylate" means alkyl acrylate and / or alkyl methacrylate.

[0067] As the alkyl (meth)acrylate, alkyl (meth)acrylates with 4 to 20 carbon atoms in the alkyl group are preferred. Specific examples of alkyl (meth)acrylates with 4 to 20 carbon atoms in the alkyl group are not particularly limited, but include, for example, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, amyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and isooctyl (meth)acrylate. Examples include 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, and eicosyl (meth)acrylate. Of these, n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA) are preferred. Alkyl (meth)acrylates may be used alone or in combination of two or more.

[0068] The content of soft monomers (adhesive monomers) is preferably 60 to 93 parts by mass, more preferably 60 to 80 parts by mass, based on 100 parts by mass of the total monomer components of the base polymer. Excellent adhesiveness can be obtained when the soft monomer content is within the above range.

[0069] As the hard monomer, a hard monomer capable of forming a hard polymer with a high glass transition temperature is preferably used. Hard monomers are useful for improving the cohesive strength of the adhesive layer. Hard monomers can be used individually or in combination of two or more.

[0070] Non-specific examples of hard monomers include, for example, N-vinylpyrrolidone (NVP), acrylonitrile (AN), methyl methacrylate (MMA), methyl acrylate (MA), vinyl acetate (VAC), and styrene.

[0071] The hard monomer content is preferably 7 to 40 parts by mass, more preferably 20 to 40 parts by mass, based on 100 parts by mass of the total monomer components of the base polymer. When the hard monomer content is within the above range, the cohesive strength and heat resistance can be further improved.

[0072] As functional monomers (copolymerizable monomers), monomers having polar groups are preferably used. Monomers having polar groups are useful for introducing crosslinking sites into the base polymer and improving the cohesive strength of the base polymer. Functional monomers can be used individually or in combination of two or more.

[0073] Non-limiting specific examples of functional monomers include, for example, hydroxyl group-containing monomers, carboxyl group-containing monomers, sulfonic acid group-containing monomers, phosphate group-containing monomers, epoxy group-containing monomers, isocyanate group-containing monomers, amide group-containing monomers, monomers having a succinimide skeleton, maleimide monomers, itacolinimide monomers, aminoalkyl (meth)acrylate monomers, alkoxyalkyl (meth)acrylate monomers, vinyl ether monomers, and olefin monomers. Of these, at least one selected from hydroxyl group-containing monomers and carboxyl group-containing monomers is preferred.

[0074] The functional monomer content is preferably 1 to 10 parts by mass, more preferably 1 to 5 parts by mass, per 100 parts by mass of the total monomer components of the base polymer. When the functional monomer content is within this range, it is possible to suppress the cohesive force of the adhesive from becoming too high and to improve its adhesiveness.

[0075] A hydroxyl group-containing monomer refers to a monomer having at least one hydroxyl group in its molecule. When a hydroxyl group-containing monomer is included in the monomer components that make up the base polymer, that is, when the base polymer contains monomer units derived from a hydroxyl group-containing monomer, secondary bonds such as hydrogen bonds are formed with the adherend, improving the cohesive force of the base polymer (preferably an acrylic polymer), more effectively suppressing changes in adhesive strength over time, resulting in less adhesive residue on the adherend after peeling and higher cohesiveness. Furthermore, by including a hydroxyl group-containing monomer in the raw material monomer of the base polymer, when a crosslinking agent is used, the crosslinking reaction with this crosslinking agent occurs effectively, allowing the adhesive effect to be fully expressed. In addition, cracking of the adherend during peeling can be effectively prevented. The base polymer in this embodiment can use one type of hydroxyl group-containing monomer, or it can use two or more types of hydroxyl group-containing monomers.

[0076] Specific examples of hydroxyl group-containing monomers include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate.

[0077] The content of hydroxyl group-containing monomers is not particularly limited, but for example, the content of hydroxyl group-containing monomers is 0.5 to 10 parts by mass, preferably 1 to 9 parts by mass, per 100 parts by mass of the total monomer components of the base polymer. When the content of hydroxyl group-containing monomers is within the above range, secondary bonds such as hydrogen bonds are formed with the adherend, improving the cohesive force of the base polymer (preferably an acrylic polymer), more effectively suppressing changes in adhesive strength over time, resulting in less adhesive residue on the adherend after peeling and higher cohesiveness. If the content of hydroxyl group-containing monomers is less than 0.5 parts by mass, sufficient adhesion cannot be obtained. Also, if the content of hydroxyl group-containing monomers exceeds 10 parts by mass, there is a concern that the adhesive strength will become too high, making blocking more likely. There is also a concern that the adherend will be more prone to cracking during the peeling process.

[0078] A carboxyl group-containing monomer is a monomer that has at least one carboxyl group in its molecule. By including a carboxyl group-containing monomer in the raw material monomer of the base polymer, secondary bonds such as hydrogen bonds are formed with the adherend, improving the cohesive force of the base polymer (preferably an acrylic polymer), more effectively suppressing changes in adhesive strength over time, resulting in less adhesive residue on the adherend after peeling and higher cohesiveness. Furthermore, by including a carboxyl group-containing monomer in the raw material monomer of the base polymer, when a crosslinking agent is used, the crosslinking reaction with the crosslinking agent occurs effectively, allowing the adhesive to fully exhibit its effect, and also effectively preventing cracking of the adherend during peeling.

[0079] Specific examples of carboxyl group-containing monomers include, for example, acrylic acid, methacrylic acid, (meth)carboxyethyl acrylate, (meth)carboxypentyl acrylate, crotonic acid, isocrotonic acid, fumaric acid, itaconic acid, maleic acid, citraconic acid, maleic anhydride, and itaconic anhydride. Of these, acrylic acid and methacrylic acid are preferred. Any one of the above carboxyl group-containing monomers may be used alone, or two or more may be used in combination.

[0080] The content of carboxyl group-containing monomers is not particularly limited, but for example, the content of carboxyl group-containing monomers is preferably 0.5 to 10 parts by mass, more preferably 1 to 6 parts by mass, per 100 parts by mass of the total monomer components of the base polymer. When the content of carboxyl group-containing monomers is within the above range, secondary bonds such as hydrogen bonds are formed with the adherend, improving the cohesive force of the base polymer (preferably an acrylic polymer), more effectively suppressing changes in adhesive strength over time, resulting in less adhesive residue on the adherend after peeling and higher cohesiveness. If the content of carboxyl group-containing monomers exceeds 10 parts by mass, there is a concern that the adhesive strength will become too high, making blocking more likely. There is also a concern that the adherend will be more prone to cracking during peeling. If the content of carboxyl group-containing monomers is less than 0.5 parts by mass, sufficient adhesion cannot be obtained.

[0081] Examples of monomers containing sulfonic acid groups include styrene sulfonic acid, allyl sulfonic acid, sodium vinyl sulfonate, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamidepropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid.

[0082] Examples of epoxy group-containing monomers include epoxy group-containing acrylates such as glycidyl (meth)acrylate and 2-ethyl glycidyl ether (meth)acrylate, allyl glycidyl ether, and (meth)acrylate-glycidyl ether.

[0083] Examples of isocyanate group-containing monomers include 2-isocyanatoethyl (meth)acrylate.

[0084] Examples of monomers containing an amide group include (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, Nn-butyl(meth)acrylamide. Examples include N-alkyl(meth)acrylamides such as lylamide; N-vinyl carboxylic acid amides such as N-vinylacetamide; and N,N-dimethylaminopropyl(meth)acrylamide, hydroxyethylacrylamide, N-hydroxymethyl(meth)acrylamide, N-hydroxyethyl(meth)acrylamide, N-methylolpropane(meth)acrylamide, N-methoxymethyl(meth)acrylamide, N-methoxyethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, and N-(meth)acryloylmorpholine.

[0085] Examples of monomers having a succinimide skeleton include N-(meth)acryloyloxymethylenesuccinimide, N-(meth)acryloyl-6-oxyhexamethylenesuccinimide, and N-(meth)acryloyl-8-oxyhexamethylenesuccinimide.

[0086] Examples of maleimide monomers include N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, and N-phenylmaleimide.

[0087] Examples of itaconimide monomers include N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, and N-laurylitaconimide.

[0088] Examples of aminoalkyl (meth)acrylate monomers include aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, and tert-butylaminoethyl (meth)acrylate.

[0089] Examples of alkoxyalkyl (meth)acrylate monomers include methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, propoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, and ethoxypropyl (meth)acrylate.

[0090] Examples of vinyl ether monomers include vinyl alkyl ethers such as methyl vinyl ether and ethyl vinyl ether.

[0091] Examples of olefin monomers include ethylene, butadiene, isoprene, and isobutylene.

[0092] The method for obtaining the base polymer is not particularly limited, and various known polymerization methods such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, and photopolymerization can be appropriately employed. For example, solution polymerization is preferably employed. When performing solution polymerization, the monomer supply method can be appropriately employed, such as a batch supply method in which all monomer raw materials are supplied at once, a continuous supply (dropping) method, or a divided supply (dropping) method. The polymerization temperature during solution polymerization can be appropriately selected depending on the type of monomer and solvent used, the type of polymerization initiator, etc., and can be, for example, about 20 to 170°C (typically about 40 to 140°C).

[0093] The solvent used in solution polymerization (polymerization solvent) can be appropriately selected from conventionally known organic solvents. For example, one or more mixed solvents selected from aromatic compounds such as toluene (typically aromatic hydrocarbons); acetic acid esters such as ethyl acetate; aliphatic or alicyclic hydrocarbons such as hexane and cyclohexane; halogenated alkanes such as 1,2-dichloroethane; lower alcohols such as isopropanol (e.g., monohydric alcohols with 1 to 4 carbon atoms); ethers such as tert-butyl methyl ether; ketones such as methyl ethyl ketone, etc., can be used.

[0094] The initiator used for polymerization can be appropriately selected from conventionally known polymerization initiators depending on the type of polymerization method. For example, one or more azo polymerization initiators such as 2,2'-azobisisobutyronitrile (AIBN) can be preferably used. Other examples of polymerization initiators include persulfates such as potassium persulfate; peroxide initiators such as benzoyl peroxide and hydrogen peroxide; substituted ethane initiators such as phenyl-substituted ethane; and aromatic carbonyl compounds. Further examples of polymerization initiators include redox initiators that combine a peroxide and a reducing agent. Such polymerization initiators may be used individually or in combination of two or more. The amount of polymerization initiator used can be the usual amount, for example, it can be selected from a range of about 0.005 parts by mass to about 1 part by mass (typically about 0.01 parts by mass to about 1 part by mass) per 100 parts by mass of the total monomer components.

[0095] The weight-average molecular weight (Mw) of the base polymer (preferably an acrylic polymer) in the technology disclosed herein is not particularly limited and may be, for example, 1,000,000 or less, and preferably 400,000 or more. Generally, when the weight-average molecular weight Mw exceeds 1,000,000, the cohesive force increases due to the entanglement of the polymer, and fluidity tends to decrease, which may result in insufficient adhesive surface area and inability to fix the adherend.

[0096] (Antistatic agent) In the present invention, the adhesive composition Y preferably further contains an antistatic agent. The antistatic agent may be the antistatic agent contained in the aforementioned adhesive composition X.

[0097] In some preferred embodiments, the content of the antistatic agent is preferably 0.01 to 15 parts by weight, more preferably 0.02 to 10 parts by weight, per 100 parts by weight of the base polymer. In some preferred embodiments, the content of the antistatic agent is preferably 0.01 parts by weight, 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, 1 part by weight, 5 parts by weight, 10 parts by weight, or 15 parts by weight, per 100 parts by weight of the base polymer. When the content of the antistatic agent is within the above range, a sufficient antistatic effect can be obtained, the static electricity generated during peeling can be sufficiently suppressed, and damage to the adherend can be avoided or reduced.

[0098] (Crosslinking agent) The adhesive composition Y of the present invention preferably further contains a crosslinking agent.

[0099] In the present invention, it is preferable that the adhesive composition Y contains a crosslinking agent in order to adjust the cohesive force, etc. As the crosslinking agent, commonly used crosslinking agents can be used, for example, epoxy crosslinking agents, isocyanate crosslinking agents, melamine crosslinking agents, aziridine crosslinking agents, metal chelate crosslinking agents, etc. By using these crosslinking agents, an appropriate crosslinking reaction occurs, the cohesive force is sufficiently improved, good adhesiveness can be ensured, and cracking of the adherend during peeling work can be effectively prevented. These crosslinking agents can be used individually or in mixtures of two or more types.

[0100] As the epoxy crosslinking agent, any compound having two or more epoxy groups in one molecule can be used without particular limitation. Epoxy crosslinking agents having three to five epoxy groups in one molecule are preferred. The epoxy crosslinking agent may be used alone or in combination of two or more types.

[0101] Specific examples of epoxy crosslinking agents, though not limited to them, include bisphenol A, epichlorohydrin-type epoxy resins, ethylene glycidyl ether, N,N,N',N'-tetraglycidylmetoxylendiamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, polyethylene glycol diglycidyl ether, and polyglycerol polyglycidyl ether. Commercially available epoxy crosslinking agents include "TETRAD-C" and "TETRAD-X" from Mitsubishi Gas Chemical Company, "EPICLON CR-5L" from DIC Corporation, "DENACOL EX-512" from Nagase ChemteX Corporation, and "TEPIC-G" from Nissan Chemical Industries, Ltd.

[0102] The amount of epoxy crosslinking agent used is not particularly limited, but for example, it is preferably 0.05 to 8 parts by mass, more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the base polymer.

[0103] In embodiments containing an epoxy crosslinking agent, the epoxy equivalent of the epoxy crosslinking agent is preferably 80 to 120 g / eq.

[0104] As isocyanate-based crosslinking agents, polyfunctional isocyanates (compounds having an average of two or more isocyanate groups per molecule, including compounds having an isocyanurate structure) are preferably used. Isocyanate-based crosslinking agents may be used alone or in combination of two or more.

[0105] Examples of polyfunctional isocyanates include aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates.

[0106] Specific examples of aliphatic polyisocyanates include butylene diisocyanates such as 1,2-ethylene diisocyanate, 1,2-butylene diisocyanate, 1,3-butylene diisocyanate, and 1,4-butylene diisocyanate; hexamethylene diisocyanates such as 1,2-hexamethylene diisocyanate, 1,3-hexamethylene diisocyanate, 1,4-hexamethylene diisocyanate, 1,5-hexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, and 2,5-hexamethylene diisocyanate; and lysine diisocyanate, among others.

[0107] Specific examples of alicyclic polyisocyanates include isophorone diisocyanate; cyclohexyl diisocyanates such as 1,2-cyclohexyl diisocyanate, 1,3-cyclohexyl diisocyanate, and 1,4-cyclohexyl diisocyanate; cyclopentyl diisocyanates such as 1,2-cyclopentyl diisocyanate and 1,3-cyclopentyl diisocyanate; hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tetramethylxylene diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate.

[0108] Specific examples of aromatic polyisocyanates include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate, and 2,2'-diphenylpropane-4,4'-diisocyanate. Examples include 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, 4,4'-diphenylpropanediisocyanate, m-phenylenediisocyanate, p-phenylenediisocyanate, naphthylene-1,4-diisocyanate, naphthylene-1,5-diisocyanate, 3,3'-dimethoxydiphenyl-4,4'-diisocyanate, xylylene-1,4-diisocyanate, and xylylene-1,3-diisocyanate.

[0109] Preferred polyfunctional isocyanates include those having an average of three or more isocyanate groups per molecule. Trifunctional or higher isocyanates can be polymers (typically dimers or trimers) of bifunctional or trifunctional or higher isocyanates, derivatives (e.g., addition reaction products of a polyhydric alcohol and two or more polyfunctional isocyanates), polymers, etc. Examples include dimers and trimers of diphenylmethane diisocyanate, isocyanurates of hexamethylene diisocyanate (trimeric adducts of isocyanurate structures), reaction products of trimethylolpropane and tolylene diisocyanate, reaction products of trimethylolpropane and hexamethylene diisocyanate, polymethylene polyphenyl isocyanate, polyether polyisocyanate, polyester polyisocyanate, and other polyfunctional isocyanates. Examples of commercially available polyfunctional isocyanates include "Duranate TPA-100" manufactured by Asahi Kasei Chemicals, "Coronate L," "Coronate HL," "Coronate HK," "Coronate HX," and "Coronate 2096" manufactured by Nippon Polyurethane Industry Co., Ltd.

[0110] In embodiments containing an isocyanate-based crosslinking agent, the isocyanate group content (NCO content) in the isocyanate-based crosslinking agent is preferably 7 to 15%.

[0111] The amount of isocyanate-based crosslinking agent used is not particularly limited, but is preferably 0.1 to 6 parts by mass, more preferably 0.5 to 5 parts by mass, per 100 parts by mass of the base polymer.

[0112] Examples of melamine-based crosslinking agents include hexamethyl melamine and butylated melamine resin (for example, DIC Corporation's product name "Super Beccamine J-820-60N").

[0113] The amount of melamine-based crosslinking agent used is not particularly limited, but for example, it is preferably 0.5 to 12 parts by mass, and preferably 1 to 8 parts by mass, per 100 parts by mass of the base polymer.

[0114] Examples of aziridine-based crosslinking agents include trimethylolpropantris[3-(1-aziridinyl)propionate] and trimethylolpropantris[3-(1-(2-methyl)aziridinylpropionate)]. Commercially available aziridine-based crosslinking agents can also be used. For example, the Chemitite series (manufactured by Nippon Shokubai Co., Ltd.), such as Chemitite PZ-33 and Chemitite DZ-22E, can be used.

[0115] Examples of metal chelating crosslinking agents include aluminum chelating compounds, titanium chelating compounds, zinc chelating compounds, zirconium chelating compounds, iron chelating compounds, cobalt chelating compounds, nickel chelating compounds, tin chelating compounds, manganese chelating compounds, and chromium chelating compounds.

[0116] The amount of crosslinking agent used is preferably 0.05 to 15 parts by mass per 100 parts by mass of the base polymer. By using the above range of crosslinking agent, the cohesive force of the adhesive can be increased, preventing adhesive residue on the adherend, and it tends to have appropriate fluidity, good wettability to the adherend, and improved adhesion. In some embodiments, from the viewpoint of avoiding a decrease in tackiness due to excessive increase in cohesive force, the amount of crosslinking agent used per 100 parts by mass of the base polymer is more preferably 1 part by mass or more, even more preferably 3 parts by mass or more, and more preferably 10 parts by mass or less, and even more preferably 8 parts by mass or less.

[0117] To carry out the above crosslinking reaction more effectively, a crosslinking catalyst can be used. As a crosslinking catalyst, a tin-based catalyst (e.g., dioctyl tin dilaurate) is preferably used. The amount of crosslinking catalyst used is not particularly limited, but for example, 0.0001 to 1 part by mass per 100 parts by mass of the base polymer is preferred.

[0118] In addition to the above components, the adhesive composition Y of the present invention may optionally contain various additives commonly used in the field of adhesives, such as photoinitiators, plasticizers, softeners, anti-aging agents, and antioxidants, to the extent that they do not impair the effects of the present invention. Conventional known additives can be used by conventional methods.

[0119] (Formation of adhesive layer Y) The adhesive layer Y disclosed herein can be formed by the same manufacturing method as the adhesive layer X described above.

[0120] The thickness of the adhesive layer Y is not particularly limited, but considering the balance between adhesion to the adherend and cohesiveness, the thickness of the adhesive layer Y is preferably 1 to 200 μm, more preferably 10 to 150 μm, even more preferably 30 to 100 μm, and even more preferably 40 to 80 μm. By setting the thickness of the adhesive layer Y within the above range, good adhesion can be obtained.

[0121] [Base material layer] The material of the base layer constituting the adhesive sheet disclosed herein is not particularly limited and can be appropriately selected according to the purpose and form of use of the adhesive sheet. Non-limited examples of usable base layers include: plastic films such as polyolefin films mainly composed of polyolefins such as polyethylene, polypropylene, polybutene, and ethylene propylene copolymer, polyvinyl chloride films mainly composed of polyvinyl chloride, films mainly composed of cast polypropylene, and thermoplastic polyurethane films; foam sheets made of foams such as polyurethane foam, polyethylene foam, and polychloroprene foam; woven and nonwoven fabrics made by single or blended fibrous materials (which may be natural fibers such as hemp and cotton, synthetic fibers such as polyester and vinylon, and semi-synthetic fibers such as acetate); papers such as Japanese paper, fine paper, kraft paper, and crepe paper; and metal foils such as aluminum foil and copper foil. Of these, the base layer preferably contains at least one selected from the group consisting of thermoplastic polyurethane, polyethylene, polypropylene, polybutene, ethylene-vinyl acetate copolymer, and polyvinyl chloride. A base material made by compounding these materials may also be used. Examples of such composite substrates include, for instance, a substrate having a structure in which metal foil and the above-mentioned plastic film are laminated, and a plastic substrate reinforced with inorganic fibers such as glass cloth.

[0122] The surface of the substrate layer of the present invention may be subjected to any surface treatment in order to improve adhesion and retention with adjacent layers. Examples of such surface treatments include chemical and physical treatments such as chromic acid treatment, ozone exposure, flame exposure, high-voltage electric shock exposure, and ionization radiation treatment, as well as coating treatments.

[0123] In the present invention, the base layer has a foaming ratio of 1.1 to 20 cm². 3 The weight is per gram, the thickness is 0.06 to 2.0 mm, and the 50% compressive strength is 100 kPa to 10000 kPa.

[0124] The foaming ratio of the substrate layer is preferably 1.3 to 15 cm². 3 / g, more preferably 1.4-8cm3 / g, more preferably 1.5-4cm 3 It is / g.

[0125] The thickness of the base material layer is preferably 0.06 to 1.8 mm, more preferably 0.1 to 1.0 mm, and even more preferably 0.15 to 0.50 mm.

[0126] The 50% compressive strength of the base material layer is preferably 200 kPa to 8000 kPa, more preferably 400 kPa to 4000 kPa, and even more preferably 1000 kPa to 3000 kPa.

[0127] (Method of manufacturing adhesive sheets) The adhesive sheet of the present invention can be manufactured by any suitable method. For example, this could involve applying adhesive compositions X and Y onto a substrate layer, or transferring a coated layer formed by applying adhesive compositions X and Y onto any suitable substrate to the substrate layer.

[0128] Any suitable coating method can be used to apply the adhesive compositions X and Y described above. For example, each layer can be formed by drying after coating. Examples of coating methods include coating using a multi-coater, die coater, gravure coater, applicator, rod coater, air knife coater, reverse roll coater, lip coater, dip coater, offset printing, flexographic printing, and screen printing. Examples of drying methods include natural drying and heat drying. In the case of heat drying, the heating temperature can be set to any suitable temperature depending on the properties of the substance to be dried.

[0129] (Application) The adhesive sheets disclosed herein can be attached to various components and devices for protective and other purposes. In particular, when used in the manufacture of electronic product components, the adhesive sheets of the present invention provide excellent adhesion between electronic product components and other components, and exhibit good heat-peelability when defects occur or when product components are repaired. [Examples]

[0130] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. The evaluation methods in the examples are as follows. In the examples, unless otherwise specified, "parts" are based on weight. If specific conditions are not specified in the examples, the process will be carried out according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, all materials and equipment used are common products that are available commercially.

[0131] (Preparation of acrylic polymer A1) In a reaction vessel equipped with a stirrer, thermometer, nitrogen inlet tube, and reflux condenser, 70 parts of n-butyl acrylate (BA) (manufactured by Zhejiang Satellite Co.), 25 parts of ethyl acrylate (EA), 5 parts of 2-hydroxyethyl acrylate (2-HEA), and 200-300 parts of toluene as a polymerization solvent were charged. The mixture was stirred at 65°C for 1.5 hours under a nitrogen atmosphere, and then 0.1 parts of 2,2'-azobisisobutyronitrile (AIBN) was added as a thermal polymerization initiator. The mixture was reacted at 65°C for 3-4 hours to obtain a solution of acrylic polymer A1.

[0132] (Preparation of acrylic polymers A2-A4) Acrylic polymers A2 to A4 were prepared in the same manner as acrylic polymer A1, except that the types and amounts of monomer components were changed as shown in Table 1. The compositions of acrylic polymers A1 to A4 are shown in Table 1.

[0133] [Table 1]

[0134] In Table 1, BA is n-butyl acrylate, EA is ethyl acrylate, 2-EHA is 2-ethylhexyl acrylate, 2-HEA is 2-hydroxyethyl acrylate, and AA is acrylic acid.

[0135] <Making adhesive sheets> Example 1 A PE foam with a thickness of 0.15 mm was used as the base layer.

[0136] 30 parts by weight of rosin resin (softening point: 50°C) and 100 parts by weight of styrene-ethylene-butylene-styrene rubber (SEBS) (styrene content: 12% by weight) were dissolved in toluene. Then, 1 part by weight of antioxidant (product name: I168) and 1 part by weight of antioxidant (product name: I565) were added and mixed to obtain a mixed solution.

[0137] Next, the mixed solution is applied to the corona-treated side of the substrate layer at a sizing amount (coating amount) of 160 g / m². 2 The adhesive layer X with a thickness of 50 μm was formed by coating under drying conditions of 110°C for 2 minutes and a production speed of 10 m / min.

[0138] To a solution of the acrylic polymer A1 described above, 3 parts of an isocyanate-based crosslinking agent (product name: Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.) were added to 1100 parts of the acrylic polymer A1 contained in the solution, and the mixture was uniformly mixed to prepare adhesive composition Y.

[0139] Adhesive composition Y was applied to the other side of the above-mentioned substrate layer and dried to form an adhesive layer Y with a thickness of 50 μm. The drying conditions were heating at 130°C for 2 minutes. An adhesive sheet was thus obtained.

[0140] Examples 2-8 and Comparative Examples 1-4 An adhesive sheet was prepared in the same manner as in Example 1, except that the base layer, adhesive layer X, and adhesive layer Y shown in Tables 2-4 were used.

[0141] The adhesive sheets obtained in the examples and comparative examples were evaluated. The results are shown in Tables 2 to 4.

[0142] In the table below, "peel force at 23°C" refers to the peel force when the adhesive layer is peeled off at 23°C in a 180° direction at a tensile speed of 300 mm / min, and "peel force at 80°C" refers to the peel force when the adhesive layer is heated at 80°C for 5 minutes and peeled off at 80°C in a 180° direction at a tensile speed of 300 mm / min.

[0143] [Table 2]

[0144] [Table 3]

[0145] [Table 4]

[0146] <Evaluation Test> (1) Expansion ratio

[0147] The foaming ratio of the above-mentioned base material layer can be calculated from the reciprocal of the density of the base material layer. For example, it can be measured in accordance with JIS K 7222.

[0148] (2) 50% compressive strength The 50% compressive strength was calculated in accordance with JIS K-6767.

[0149] (3) Peeling force at 23°C Test specimens measuring 20 mm in width and 150 mm in length were cut from the adhesive sheets of each example and comparative example. A SUS plate (SUS430BA plate) cleaned with toluene was used as the adherend. Under standard conditions of 23°C and 50% RH, a 25 μm PET backing was attached to the other side of the test surface, and then a 2 kg roller was passed back and forth once to press the test surface of the test specimen against the adherend. After the test specimen pressed against the adherend was left in the above standard conditions for 30 minutes, it was peeled using a tensile testing machine (Shimadzu Corporation, product name "Tensilon") in accordance with JIS Z 0237, at a tensile speed of 300 mm / min and a peeling angle of 180°, and the 180° peeling force (N / 20 mm) was measured.

[0150] (4) Peeling force at 80°C Test specimens measuring 20 mm in width and 150 mm in length were cut from the adhesive sheets of each example and comparative example. A SUS plate (SUS430BA plate) cleaned with toluene was used as the adherend. Under standard conditions of 23°C and 50% RH, a 25 μm PET backing was attached to the other side of the test surface, and then a 2 kg roller was passed back and forth once to press the test surface of the test specimen against the adherend. The test specimens pressed against the adherend in this manner were heated at 80°C for 5 minutes, and then, in accordance with JIS Z 0237, they were peeled at 80°C, at a tensile speed of 300 mm / min, and at a peel angle of 180° using a tensile testing machine (Shimadzu Corporation, product name "Tensilon"), and the 180° peel force (N / 20 mm) was measured.

[0151] (5) Storage modulus G' of the adhesive layer The temperature of the adhesive composition was scanned in vibration mode using a TA Corporation ARES G2 rotary ometer at a frequency of 10,000 Hz and a temperature range of -70°C to 100°C. The storage modulus at 25°C was defined as G'.

[0152] (6) Reworkability of flexible composite foam One side of a 20mm x 20mm Nitto SCF400 foam was fixed to a SUS steel plate with Nitto NO.5000NS tape (same size as the SCF foam), and the other side of the SCF400 foam was attached to Nitto NO.5000NS tape (same size as the SCF foam) which had a 0.05mm thick PET film composite on one side. The adhesive layer X was applied to the PET surface, which was a composite of the SUS steel plate, SCF400, and PET sheet, using a 2kg roller at a speed of 300mm / min, and then the adhesive layer Y was similarly applied to the SUS steel plate. After being left at room temperature (23℃) for 30 minutes, the samples were peeled off at room temperature using a tensile testing machine (Shimadzu Corporation, product name "Tensilon") at a tensile speed of 50mm / min perpendicular to the direction of the adhesive layer to check for damage to the SCF400 and to check the adhesion between adhesive layer Y and the SUS plate. Furthermore, the experiment was conducted similarly at 80°C to confirm whether or not the SCF400 was damaged, and to verify the adhesion between the adhesive layer Y and the SUS plate.

[0153] If damage occurs when the SCF is peeled off at 23°C, but no damage occurs when the SCF is peeled off at 80°C, and the adhesion between the adhesive layer Y and the SUS plate is good at both 23°C and 80°C, then the reworkability is judged to be OK, as this means that the adhesive layer X has high adhesion at 23°C, is easy to peel off at 80°C, and the adhesive layer Y maintains good adhesion at both 23°C and 80°C. If no damage occurs when the SCF400 is peeled off at 23°C, or if damage occurs when the SCF400 is peeled off at 80°C, or if peeling or partial peeling occurs between the adhesive layer Y and the SUS plate at both 23°C and 80°C, then the reworkability is judged to be NG, as this indicates that the adhesive layer X has low adhesion at 23°C or does not peel off easily at 80°C, or that the adhesive layer Y cannot maintain good adhesion at both 23°C and 80°C.

[0154] As shown in the table above, the adhesive sheets of Examples 1 to 8 achieved both excellent adhesion and heat-removable properties, and could be easily removed by heating after use without causing deformation or damage to the adherend. On the other hand, the adhesive sheets of Comparative Examples 1 to 4 either failed to achieve excellent adhesion or were prone to deformation or damage to the adherend.

Claims

1. An adhesive sheet having a base layer, an adhesive layer X disposed on one side of the base layer, and an adhesive layer Y disposed on the other side of the base layer, Let A be the peeling force when the adhesive layer X is peeled off at 23°C in a 180° direction at a tensile speed of 300 mm / min, and let B be the peeling force when the adhesive layer Y is peeled off at 23°C in a 180° direction at a tensile speed of 300 mm / min, where A / B = 0.5 to 2. An adhesive sheet characterized in that the peeling force when the adhesive layer X is heated at 80°C for 5 minutes and peeled off at a tensile speed of 300 mm / min in a 180° direction at 80°C is C, and the peeling force when the adhesive layer Y is heated at 80°C for 5 minutes and peeled off at a tensile speed of 300 mm / min in a 180° direction at 80°C is D, and C / D = 0.002 to 0.

2.

2. The adhesive sheet according to claim 1, characterized in that the peeling force when the adhesive layer X is peeled off at 23°C in a 180° direction at a tensile speed of 300 mm / min is 2 to 40 N / 20 mm, and the peeling force when the adhesive layer X is heated at 80°C for 5 minutes and peeled off at 80°C in a 180° direction at a tensile speed of 300 mm / min is 0.01 to 4 N / 20 mm.

3. The adhesive sheet according to claim 1, characterized in that the peeling force when the adhesive layer Y is peeled off at 23°C in a 180° direction at a tensile speed of 300 mm / min is 4 to 40 N / 20 mm, and the peeling force when the adhesive layer Y is heated at 80°C for 5 minutes and peeled off at 80°C in a 180° direction at a tensile speed of 300 mm / min is 5 to 40 N / 20 mm.

4. The adhesive sheet according to any one of claims 1 to 3, wherein the adhesive layer X comprises rubber and a tackifying resin, and the content of the tackifying resin is 5 to 120 parts by weight per 100 parts by weight of rubber.

5. The adhesive sheet according to claim 4, characterized in that the rubber is one or more selected from styrene-ethylene-butylene-styrene rubber, styrene-butadiene-styrene rubber, styrene-butadiene rubber, and styrene-isoprene-styrene rubber.

6. The adhesive sheet according to claim 4, characterized in that the styrene content in the rubber is 5 to 25% by weight.

7. The adhesive sheet according to claim 4, wherein the tackifying resin is one or more selected from rosin resin, modified rosin resin, terpene resin, and C5 / C9 tackifying resin, and the tackifying resin has a softening point of 50 to 85°C or a viscosity of 1,000 to 20,000 cP at 23°C.

8. The adhesive sheet according to any one of claims 1 to 3, characterized in that the adhesive layer Y contains an acrylic polymer, and the storage modulus G' of the adhesive layer Y at 25°C is 35 kPa to 500 kPa.

9. The aforementioned substrate layer has a foaming ratio of 1.1 to 20 cm ３ The adhesive sheet according to any one of claims 1 to 3, characterized in that the strength is / g, the thickness is 0.06 to 2.0 mm, the 50% compressive strength is 100 kPa to 10000 kPa, and the thickness of the adhesive layer X and the adhesive layer Y is each 1 to 200 μm.

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