Composition for self-adhesive foam sheet and self-adhesive foam laminate sheet

Abstract

The purpose of the present invention is to provide a composition for a self-adhesive foam sheet that can be used to obtain a self-adhesive foam layered sheet having excellent air venting properties after heating and pressurization. The composition for a self-adhesive foam sheet according to the present invention contains a polymer, a crosslinking agent, and a wax agent.

Description

[Technical Field]

[0001] The present invention relates to a composition for a self-adhesive foam sheet and a self-adhesive foam laminate sheet. [Background technology]

[0002] In recent years, sheet-like components with self-adhesive properties, i.e., self-adhesive foam sheets (hereinafter sometimes abbreviated as "foam sheets"), made of a foam material with numerous micropores, have been used as adhesive sheets to be attached to smooth substrates such as window glass. The adhesive mode of self-adhesive foam sheets is not glue adhesion, but rather adhesion to the substrate utilizing the micropores. Therefore, self-adhesive foam sheets are easier to reposition than conventional adhesive sheets that use glue adhesion, and are suitable for applications such as wallpaper, posters, and stickers. When used for these applications, self-adhesive foam sheets are typically used in the form of self-adhesive foam laminate sheets (hereinafter sometimes abbreviated as "laminate sheets") laminated on a substrate. By applying decoration such as printing to the substrate-side surface of this self-adhesive foam laminate sheet, it can be advantageously used for the above-mentioned applications.

[0003] In order to improve the performance of self-adhesive foam laminate sheets, improvements have been made to the compositions used to prepare the foam sheets that make up the laminate sheets (hereinafter referred to as "compositions for self-adhesive foam sheets" and sometimes abbreviated as "compositions for foam sheets").

[0004] For example, Patent Document 1 proposes a composition for a foam sheet containing a polymer having predetermined properties and a crosslinking agent. A laminate sheet including a foam sheet formed from the foam sheet composition of Patent Document 1 can suppress resin residue on glass as an adherend even after weathering. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2018 / 151274 Summary of the Invention [Problem to be solved by the invention]

[0006] Here, the laminate sheet is required to have the property of easily removing air trapped between the sheet and the adherend when the foam sheet side is adhered to the adherend (i.e., excellent air release properties). In particular, since the laminate sheet may be exposed to a high-temperature and pressurized environment during transportation, it is required to maintain excellent air release properties even after heating and pressurization (i.e., excellent air release properties after heating and pressurization). However, according to the investigations of the present inventors, the above-mentioned conventional compositions for foam sheets still have room for improvement in terms of air release properties after heating and pressurization.

[0007] Therefore, an object of the present invention is to provide a self-adhesive foam laminate sheet that has excellent air release properties after heating and pressurizing, and a composition for a self-adhesive foam sheet that can be used to obtain the self-adhesive foam laminate sheet. [Means for solving the problem]

[0008] The present inventors have conducted extensive research to solve the above-mentioned problems, and have found that forming a foam sheet using a foam sheet composition containing a polymer, a crosslinking agent, and a wax agent allows a laminate sheet including the foam sheet to exhibit excellent air release properties even after heating and pressurization, thereby completing the present invention.

[0009] The present invention aims to advantageously solve the above-mentioned problems, and provides a self-adhesive foam sheet composition comprising a polymer, a crosslinking agent, and a wax. Thus, by forming a foam sheet using a foam sheet composition comprising a polymer, a crosslinking agent, and a wax, a laminate sheet including the foam sheet can exhibit excellent air release properties even after heating and pressurizing.

[0010] In the self-adhesive foam sheet composition of the present invention, the polymer preferably contains 60% by mass or more and 99% by mass or less of (meth)acrylate monomer units. By using a foam sheet composition containing a polymer containing (meth)acrylate monomer units in the above-mentioned ratio, it is possible to obtain a laminated sheet that maintains good self-adhesion (adhesion to the adherend) while suppressing resin residue on the adherend. In the present invention, the phrase "containing a monomer unit" means that "a polymer obtained using the monomer contains a repeating unit derived from the monomer." Furthermore, in the present invention, "(meth)acrylate" means acrylate and / or methacrylate.

[0011] In addition, in the self-adhesive foam sheet composition of the present invention, the polymer preferably contains 0.1% by mass or more and 10% by mass or less of unsaturated carboxylic acid monomer units. By using a foam sheet composition containing a polymer containing unsaturated carboxylic acid monomer units in the above-mentioned ratio, sufficient strength can be imparted to the foam sheet. Furthermore, a laminated sheet can be obtained that maintains good self-adhesion while suppressing resin residue on the adherend.

[0012] In the self-adhesive foam sheet composition of the present invention, the polymer preferably does not have an N-methylol group. Use of a foam sheet composition containing a polymer that does not have an N-methylol group can sufficiently suppress the generation of formaldehyde during foaming and curing of the foam sheet composition.

[0013] In the composition for a self-adhesive foam sheet of the present invention, the wax agent preferably contains a fatty acid ester having a fatty acid moiety with a carbon number of 16 to 34. Using a fatty acid ester having a fatty acid moiety (a structure derived from a fatty acid in a fatty acid ester) with a carbon number within the above range as the wax agent can further improve the air release properties of the laminate sheet after heating and pressing.

[0014] Furthermore, in the composition for self-adhesive foam sheets of the present invention, the amount of the fatty acid ester blended is preferably 0.5 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the polymer. By using a composition for foam sheets in which the amount of the specified fatty acid ester blended per 100 parts by mass of the polymer falls within the above-mentioned range, the air release properties of the laminate sheet after heating and pressurizing can be further improved.

[0015] In the composition for a self-adhesive foam sheet of the present invention, the fatty acid ester preferably has an alcohol moiety with a carbon number of 30 to 34. If a fatty acid ester having an alcohol moiety (a structure derived from the alcohol in the fatty acid ester) with a carbon number within the above range is used as the waxing agent, the air release properties of the laminate sheet after heating and pressing can be further improved.

[0016] The present invention aims to advantageously solve the above-mentioned problems, and provides a self-adhesive foam laminate sheet comprising a substrate and a self-adhesive foam sheet formed using any of the above-mentioned compositions for a self-adhesive foam sheet, characterized in that the substrate is a paper substrate other than a synthetic paper substrate, a plastic substrate, a fiber substrate, a metal substrate, or a glass substrate. Thus, a laminate sheet comprising a foam sheet formed from the above-mentioned foam sheet composition on a paper substrate other than a synthetic paper substrate, a plastic substrate, a fiber substrate, a metal substrate, or a glass substrate has excellent air release properties after heating and pressurization. In the present invention, the term "synthetic paper" refers to a film made from a resin composition containing a thermoplastic resin and a filler. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide a self-adhesive foam laminate sheet that has excellent air release properties after heating and pressurizing, and a composition for a self-adhesive foam sheet that can be used to obtain the self-adhesive foam laminate sheet. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a flowchart illustrating an example of a method for producing a self-adhesive foam laminate sheet according to the present invention. [Figure 2] FIG. 1 is an explanatory diagram showing the schematic configuration of an evaluation device used to evaluate the air release properties of self-adhesive foam laminate sheets in Examples and Comparative Examples. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described in detail. The self-adhesive foam sheet composition of the present invention can be suitably used to obtain a self-adhesive foam sheet, which is a component of the self-adhesive foam laminate sheet of the present invention. The self-adhesive foam laminate sheet of the present invention comprises a self-adhesive foam sheet formed using the self-adhesive foam sheet composition of the present invention.

[0020] (Self-adhesive foam sheet composition) The foam sheet composition of the present invention comprises a polymer, a crosslinking agent, and a wax agent, and optionally further contains a solvent and other additives. Furthermore, by forming a foamed sheet using the foamable sheet composition of the present invention on a paper substrate other than a synthetic paper substrate, a plastic substrate, a fiber substrate, a metal substrate, or a glass substrate, a laminated sheet having excellent air release properties after heating and pressurizing can be obtained.

[0021] <Polymer> The polymer used in the foam sheet composition of the present invention forms a resin matrix in the foam sheet obtained by foaming and crosslinking the foam sheet composition.

[0022] Here, the polymer is not particularly limited, but may contain, for example, at least one monomer unit selected from the group consisting of (meth)acrylate monomer units, unsaturated carboxylic acid monomer units, vinyl cyanide monomer units, and alkenyl aromatic monomer units. The polymer may also contain monomer units other than (meth)acrylate monomer units, unsaturated carboxylic acid monomer units, vinyl cyanide monomer units, and alkenyl aromatic monomer units (hereinafter referred to as "other monomer units").

[0023] <<(Meth)acrylate monomer unit>> The (meth)acrylate monomer unit is a repeating unit derived from a (meth)acrylate monomer. When the polymer contains the (meth)acrylate monomer unit, flexibility is imparted to the resulting foamed sheet, and a laminated sheet having good self-adhesive strength can be obtained.

[0024] The (meth)acrylate monomer is not particularly limited, but examples thereof include (meth)acrylic acid alkyl ester monomers such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, sec-butyl (meth)acrylate, n-heptyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and n-dodecyl (meth)acrylate; and (meth)acrylic acid alkoxyalkyl ester monomers such as 2-methoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, and ethoxymethyl (meth)acrylate. The (meth)acrylate monomers may be used alone or in combination of two or more. In the present invention, "(meth)acrylic" means acrylic and / or methacrylic.

[0025] Here, as the (meth)acrylate monomer, from the viewpoint of further increasing the flexibility of the foamed sheet and further ensuring the self-adhesive strength of the laminated sheet, a (meth)acrylic acid alkyl ester monomer is preferred, and a (meth)acrylic acid alkyl ester monomer having 1 to 14 carbon atoms in the alkyl group (bonded to a non-carbonyl oxygen atom) (hereinafter, sometimes abbreviated as "C1-14 (meth)acrylic acid alkyl ester monomer") is more preferred.

[0026] Examples of C1-14 (meth)acrylic acid alkyl ester monomers include methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, sec-butyl acrylate, n-heptyl acrylate, n-hexyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, n-octyl methacrylate, and n-dodecyl methacrylate. Among these, n-butyl acrylate, ethyl acrylate, and 2-ethylhexyl acrylate are preferred from the viewpoints of self-adhesive strength and cost.

[0027] The proportion of (meth)acrylate monomer units in the polymer is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 85% by mass or more, and preferably 99% by mass or less, more preferably 95% by mass or less, and even more preferably 92% by mass or less, where 100% by mass is the total repeating units (total monomer units) contained in the polymer. If the proportion of (meth)acrylate monomer units in the polymer is 60% by mass or more, the self-adhesive strength of the laminate sheet can be sufficiently ensured. On the other hand, if the proportion of (meth)acrylate monomer units in the polymer is 99% by mass or less, the self-adhesive strength of the laminate sheet will not be excessively increased. Therefore, resin residue on the laminate sheet's adherend can be reduced.

[0028] <<Unsaturated carboxylic acid monomer unit>> The unsaturated carboxylic acid monomer unit is a repeating unit derived from an unsaturated carboxylic acid monomer. Specific examples of unsaturated carboxylic acid monomers include α,β-ethylenically unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid; α,β-ethylenically unsaturated polycarboxylic acids such as itaconic acid, maleic acid, and fumaric acid; and α,β-ethylenically unsaturated polycarboxylic acid partial esters such as monomethyl itaconate, monobutyl maleate, and monopropyl fumarate. Furthermore, those having a group that can be converted to a carboxylic acid group by hydrolysis, such as maleic anhydride and itaconic anhydride, can also be used. Among these, itaconic acid, acrylic acid, and methacrylic acid are preferred, and acrylic acid is more preferred, from the viewpoints of reactivity with the crosslinking agent described below, the stability of the polymer latex, and cost. The unsaturated carboxylic acid monomers may be used alone or in combination of two or more.

[0029] The proportion of unsaturated carboxylic acid monomer units in the polymer is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1% by mass or more, and preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 2.5% by mass or less, based on 100% by mass of all repeating units (total monomer units) contained in the polymer. Having a proportion of unsaturated carboxylic acid monomer units of 0.1% by mass or more in the polymer allows the crosslinking reaction by the crosslinking agent described below to proceed sufficiently. As a result, the resulting foamed sheet can be imparted with sufficient strength while suppressing resin residue on the laminate sheet's adherend. Having a proportion of unsaturated carboxylic acid monomer units of 10% by mass or less in the polymer makes it easy to maintain the viscosity of the polymerization system during polymerization within an appropriate range and also prevents excessive crosslinking of the polymer, which would impair the self-adhesive strength of the laminate sheet.

[0030] <<Vinyl cyanide monomer unit>> The vinyl cyanide monomer unit is a repeating unit derived from a vinyl cyanide monomer. Specific examples of vinyl cyanide monomers include α,β-ethylenically unsaturated nitrile monomers. The α,β-ethylenically unsaturated nitrile monomer is not particularly limited as long as it is an α,β-ethylenically unsaturated compound having a nitrile group, and examples thereof include acrylonitrile; α-halogenoacrylonitriles such as α-chloroacrylonitrile and α-bromoacrylonitrile; and α-alkylacrylonitriles such as methacrylonitrile and α-ethylacrylonitrile. Among these, acrylonitrile is preferred from the viewpoints of improving the cohesive strength of the foam sheet composition and increasing the breaking strength of the foam sheet. The vinyl cyanide monomers may be used alone or in combination of two or more.

[0031] The proportion of vinyl cyanide monomer units in the polymer is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, particularly preferably 8% by mass or more, and preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less, based on 100% by mass of all repeating units (total monomer units) contained in the polymer. When the proportion of vinyl cyanide monomer units in the polymer is 1% by mass or more, the resulting foamed sheet can be imparted with sufficient strength while suppressing resin residue on the laminate sheet's adherend. On the other hand, when the proportion of vinyl cyanide monomer units in the polymer is 30% by mass or less, the resulting foamed sheet can be sufficiently flexible, resulting in a laminate sheet with good self-adhesive strength.

[0032] <<Alkenyl aromatic monomer unit>> The alkenyl aromatic monomer unit is a repeating unit derived from an alkenyl aromatic monomer. Specific examples of the alkenyl aromatic monomer include styrene, α-methylstyrene, α-chlorostyrene, vinyltoluene, and divinylbenzene. Among these, styrene is preferred from the viewpoints of polymerizability and cost. The alkenyl aromatic monomers may be used alone or in combination of two or more.

[0033] The proportion of alkenyl aromatic monomer units in the polymer is preferably 0.5% by mass or more, more preferably 1% by mass or more, even more preferably 1.5% by mass or more, particularly preferably 2% by mass or more, and preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, based on 100% by mass of all repeating units (total monomer units) contained in the polymer. When the proportion of alkenyl aromatic monomer units in the polymer is 0.5% by mass or more, the hydrophobicity of the alkenyl aromatic monomer units can prevent water penetration into the foamed sheet, thereby improving the water resistance of the laminated sheet. On the other hand, when the proportion of alkenyl aromatic monomer units in the polymer is 20% by mass or less, the flexibility of the resulting foamed sheet can be sufficiently ensured, resulting in a laminated sheet with good self-adhesive strength.

[0034] <<Other monomer units>> The other monomer units are repeating units derived from other monomers copolymerizable with the above-mentioned monomers. Examples of the other monomers include conjugated diene monomers, α,β-ethylenically unsaturated polycarboxylic acid complete ester monomers, carboxylic acid unsaturated alcohol ester monomers, olefinic monomers, and other monomers having functional groups. These monomers may be used alone or in combination of two or more. Specific examples of such other monomers are not particularly limited, and include those described in International Publication No. 2018 / 151274.

[0035] In order to sufficiently suppress the generation of formaldehyde during foaming and curing of the foam sheet composition, the polymer preferably does not have an N-methylol group. More specifically, the polymer preferably does not contain a monomer unit having an N-methylol group. Here, examples of the monomer having an N-methylol group include N-methylolacrylamide and N-methylolmethacrylamide.

[0036] <<Properties>> [Glass transition temperature] Here, the glass transition temperature of the polymer is preferably −10° C. or lower, more preferably −13° C. or lower, even more preferably −17° C. or lower, even more preferably −20° C. or lower, and particularly preferably −26° C. or lower. If the glass transition temperature of the polymer is −10° C. or lower, the laminate sheet can be well adhered to the adherend while ensuring sufficient self-adhesive strength, thereby preventing moisture from penetrating between the adherend and the laminate sheet. This can improve the water resistance of the laminate sheet. The lower limit of the glass transition temperature of the polymer is not particularly limited, but is preferably −40° C. or higher from the viewpoint of sufficiently suppressing resin residue on the adherend of the laminated sheet. The glass transition temperature of the polymer can be measured by the method described in the examples of this specification.

[0037] [Gel fraction] Here, the gel fraction of the polymer is preferably 95% by mass or less, more preferably 93% by mass or less, and even more preferably 91% by mass or less. A gel fraction of 95% by mass or less allows for the production of foamed sheets and laminated sheets with appropriate self-adhesive strength and excellent smoothness. The lower limit of the gel fraction of the polymer is not particularly limited, but can be, for example, 50% by mass or more, 70% by mass or more, or 80% by mass or more. The gel fraction of the polymer can be measured by the method described in the examples of this specification.

[0038] <<Polymer Preparation Method>> The polymerization method for obtaining the polymer is not particularly limited, and may be any of solution polymerization, emulsion polymerization, suspension polymerization, bulk polymerization, etc., or other methods. There are also no particular limitations on the types and amounts of polymerization initiators, emulsifiers, dispersants, etc. used in the polymerization. There are also no particular limitations on the methods for adding monomers, polymerization initiators, emulsifiers, dispersants, etc. during polymerization. There are also no particular limitations on the polymerization temperature, pressure, stirring conditions, etc. The polymer can be used in a solid state. However, when the polymer is used in the form of a latex containing the polymer (polymer latex), such as a latex obtained by emulsion polymerization or a latex obtained by post-emulsification of a polymer, the operation of mixing the polymer with a crosslinking agent, a wax agent, etc. is easy, and it is also convenient for foaming the resulting foamable sheet composition. Here, when the polymer is used in the form of a polymer latex for preparing a foam sheet composition as described above, the solids concentration of the polymer latex is preferably 40% by mass or more, more preferably 45% by mass or more, even more preferably 50% by mass or more, particularly preferably 52% by mass or more, from the viewpoint of maintaining the density of the resulting foam sheet, and is preferably 70% by mass or less, more preferably 58% by mass or less.

[0039] <Crosslinking agent> The crosslinking agent contained in the foam sheet composition of the present invention is not particularly limited as long as it can form a crosslinked structure with the above-mentioned polymer (especially the unsaturated carboxylic acid monomer unit of the above-mentioned polymer). Examples of such crosslinking agents include carbodiimide-based crosslinking agents, epoxy-based crosslinking agents, oxazoline-based crosslinking agents, polyfunctional isocyanate-based crosslinking agents such as tolylene diisocyanate, trimethylolpropane tolylene diisocyanate, and diphenylmethane triisocyanate, metal salt-based crosslinking agents, metal chelate-based crosslinking agents, and peroxide-based crosslinking agents. Among these, epoxy-based crosslinking agents are preferred, and compounds having two or more epoxy groups in one molecule are more preferred. Fatty acid polyglycidyl ethers, glycerol polyglycidyl ethers, and ethylene glycol diglycidyl ethers are preferred as epoxy-based crosslinking agents.

[0040] Here, the epoxy-based crosslinking agent may be synthesized by a known method, or a commercially available product may be used. An example of a commercially available epoxy-based crosslinking agent is "Rikabond (registered trademark)" manufactured by Japan Coating Resin Co., Ltd. Epoxy-based crosslinking agents form crosslinked structures within or between polymer molecules by reacting their epoxy groups with functional groups in the polymer (e.g., carboxylic acid groups derived from unsaturated carboxylic acid monomer units). The use of epoxy-based crosslinking agents allows for the formation of foamed sheets with adequate self-adhesive strength and excellent strength. Therefore, the use of a foamed sheet composition containing an epoxy-based crosslinking agent as a crosslinking agent can reduce resin residue on the laminated sheet substrate.

[0041] In the present invention, it is preferable not to use a crosslinking agent that generates formaldehyde, such as a melamine-formaldehyde resin, a urea-formaldehyde resin, or a phenol-formaldehyde resin.

[0042] The amount of crosslinking agent in the foam sheet composition is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, even more preferably 3 parts by mass or more, particularly preferably 5.5 parts by mass or more, and preferably 20 parts by mass or less, and more preferably 10 parts by mass or less, per 100 parts by mass of the polymer. By incorporating the crosslinking agent in the above-described range, a foam sheet can be obtained that maintains appropriate strength and elasticity. Therefore, when pressure applied to the foam sheet is released, the collapsed foam cells in the foam sheet can recover to their original shape. This ensures the self-adhesive strength of the laminate sheet and sufficiently prevents resin residue from remaining on the laminate sheet's adherend.

[0043] <Wax agent> The wax agent contained in the foam sheet composition of the present invention is not particularly limited as long as it contains a fatty acid ester (particularly an ester of a higher fatty acid and a higher alcohol). The content of the fatty acid ester in the wax agent is preferably more than 50% by mass and less than 100% by mass (i.e., the main component), more preferably 70% by mass or more and less than 100% by mass, even more preferably 80% by mass or more and less than 100% by mass, and particularly preferably 90% by mass or more and less than 100% by mass, based on 100% by mass of the entire wax agent. The wax agent may contain one type of fatty acid ester, or may contain two or more types of fatty acid esters.

[0044] The wax functions as a light release agent in a foam sheet formed using the foam sheet composition. Foaming and curing a foam sheet composition containing the above-described polymer and wax agent blended therein to form a foam sheet is presumably because the light release property improves recovery even when the insides of the open cells of the foam sheet are pressed together. This also contributes to the excellent air release properties of a laminate sheet including the foam sheet after heating and pressurization.

[0045] The waxing agent may be a natural wax, a synthetic wax, or a mixture thereof, but it is preferable to use a natural wax. Specific examples of natural waxes include, but are not limited to, those containing naturally occurring fatty acid esters. Examples include plant-derived natural waxes such as rice bran wax, sugarcane wax, carnauba wax, candelilla wax, jojoba oil, Japan wax, and Moringa seed oil; animal-derived natural waxes such as beeswax, sperm whale oil, and wool fat; and mineral-derived natural waxes such as montan wax, ozokerite, and ceracin. Among these, Moringa seed oil is preferred from the viewpoint of further improving the air release properties of the laminated sheet after heating and pressing. These natural waxes may be refined from natural materials by known methods, or commercially available products may be used. An example of a commercially available natural wax is "Refined Moringa Oil" manufactured by Nitto Bussan Shoji Co., Ltd. The wax agents may be used alone or in combination of two or more.

[0046] Furthermore, the fatty acid moiety of the fatty acid ester contained in the wax preferably has 16 or more carbon atoms, more preferably 18 or more carbon atoms, and preferably 34 or less carbon atoms, and more preferably 30 or less carbon atoms. If the carbon number of the fatty acid moiety of the fatty acid ester is within the above-mentioned range, the air release properties of the laminated sheet after heating and pressurization can be further improved. Specific examples of fatty acids having 16 to 34 carbon atoms include saturated fatty acids such as stearic acid (18 carbon atoms), arachidic acid (20 carbon atoms), and behenic acid (22 carbon atoms); and unsaturated fatty acids such as oleic acid (18 carbon atoms), linoleic acid (18 carbon atoms), and linolenic acid (18 carbon atoms). These fatty acids may be used alone or in combination of two or more.

[0047] The alcohol portion of the fatty acid ester contained in the wax preferably has 30 or more carbon atoms, and preferably 34 or less carbon atoms. If the carbon number of the alcohol portion of the fatty acid ester is within the above-mentioned range, the air release properties of the laminated sheet after heating and pressurization can be further improved. Specific examples of alcohols having 30 or more and 34 or less carbon atoms include myricyl alcohol (30 carbon atoms), melissyl alcohol (31 carbon atoms), lacceryl alcohol (32 carbon atoms), celometrilic alcohol (33 carbon atoms), and tetratriacontanol (34 carbon atoms). These alcohols may be used alone or in combination of two or more.

[0048] The amount of wax in the foam sheet composition is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, even more preferably 1.5 parts by mass or more, and particularly preferably 3.6 parts by mass or more, and is preferably 10 parts by mass or less, more preferably 7 parts by mass or less, and even more preferably 5 parts by mass or less, per 100 parts by mass of the polymer. When the amount of wax is 0.5 parts by mass or more per 100 parts by mass of the polymer, the air release properties of the laminate sheet after heating and pressing can be further improved. On the other hand, when the amount of wax is 10 parts by mass or less per 100 parts by mass of the polymer, the resulting laminate sheet can be imparted with good self-adhesive strength and the air release properties of the laminate sheet after heating and pressing can be further improved. The amount of the fatty acid ester having a fatty acid moiety with 16 to 34 carbon atoms in the foam sheet composition is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, even more preferably 1.5 parts by mass or more, and preferably 10 parts by mass or less, more preferably 7 parts by mass or less, and even more preferably 5 parts by mass or less, per 100 parts by mass of the polymer. When the amount of the fatty acid ester having a fatty acid moiety with 16 to 34 carbon atoms is 0.5 parts by mass or more per 100 parts by mass of the polymer, the air release properties of the laminate sheet after heating and pressing can be further improved. On the other hand, when the amount of the fatty acid ester having a fatty acid moiety with 16 to 34 carbon atoms is 10 parts by mass or less per 100 parts by mass of the polymer, the resulting laminate sheet can be imparted with good self-adhesive strength and the air release properties of the laminate sheet after heating and pressing can be further improved.

[0049] <Solvent> The solvent that the foam sheet composition of the present invention may optionally contain is not particularly limited, but is preferably water. When water is used as the solvent, the water contained in the foam sheet composition may be, for example, water derived from the polymer latex.

[0050] <Other additives> The foam sheet composition of the present invention can optionally contain various additives to improve processability during the production process of foam sheets and laminate sheets and to improve the performance of the resulting foam sheets and laminate sheets. Examples of such additives include foam stabilizers such as higher fatty acid salts and surfactants, foaming aids, thickeners, fillers, preservatives, mildew inhibitors, gelling agents, flame retardants, antioxidants, antioxidants, pigments, dyes, tackifiers, conductive compounds, water-resistant agents, and oil-resistant agents. Specific examples of the other additives mentioned above are not particularly limited, and known additives, such as those described in International Publication No. 2016 / 147679, can be used.

[0051] (Self-adhesive foam laminate sheet) The laminate sheet of the present invention has a foam layer made of a foam sheet obtained using the foam sheet composition of the present invention described above, and a substrate as a support layer supporting the foam layer. The foam sheet may be formed directly on the substrate, or may be formed on the substrate via an optional layer.

[0052] <Self-adhesive foam sheet> The self-adhesive foam sheet that forms the foam layer in the laminate sheet of the present invention is formed by crosslinking and foaming the foam sheet composition of the present invention. Here, the density of the self-adhesive foam sheet is not particularly limited, but is preferably 0.1 g / cm 3 More than 1.0g / cm 3 It is preferable that the concentration is 0.3 g / cm or less. 3 More than 0.8g / cm 3 More preferably, it is 0.5 g / cm or less. 3 More than 0.7g / cm 3 It is more preferable that the density of the foamed sheet is 0.1 g / cm or less. 3 If the density is above 1.0 g / cm, the strength of the foam sheet is ensured. 3 If the ratio is less than this, the air release property of the laminated sheet after heating and pressurizing can be further improved, while the resin remaining on the adherend can be sufficiently suppressed. The density of the foamed sheet can be calculated using the method described in the examples of this specification. The thickness of the foam sheet is preferably 0.03 mm or more, more preferably 0.05 mm or more, and even more preferably 0.1 mm or more, and is preferably 3 mm or less, more preferably 1 mm or less, even more preferably 0.5 mm or less, and particularly preferably 0.2 mm or less. When the thickness of the foam sheet is 0.03 mm or more, the mechanical strength of the foam sheet and the laminate sheet can be sufficiently ensured. On the other hand, when the thickness of the foam sheet is 3 mm or less, the air release property of the laminate sheet after heating and pressurizing can be further improved. Furthermore, a laminate sheet with excellent repetitive application properties (reworkability) can be obtained.

[0053] <Base material> As the substrate in the laminate sheet of the present invention, a paper substrate other than a synthetic paper substrate, a plastic substrate, a fiber substrate, a metal substrate, or a glass substrate can be used. The thickness of the substrate is not particularly limited, but can be, for example, 10 μm or more and 200 μm or less.

[0054] <<Paper base material>> The paper substrate is not particularly limited as long as it is not a synthetic paper substrate, and examples thereof include fine paper, art paper, coated paper, kraft paper, and these paper substrates laminated with a thermoplastic resin such as polyethylene.

[0055] <<Plastic substrate>> Examples of plastic substrates include polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polystyrene resins; polyvinyl chloride resins; acrylic resins; polycarbonate resins; polyamide resins; fluorine-based resins such as polytetrafluoroethylene; and sheet-like substrates made of mixtures or laminates of these resins.

[0056] <<Fiber base material>> Examples of fibrous substrates include natural fibers such as cotton and silk; polyamide synthetic fibers; polyester synthetic fibers; polypropylene synthetic fibers; polyvinyl chloride synthetic fibers; polyvinyl alcohol synthetic fibers; semi-synthetic fibers such as acetate; regenerated artificial fibers such as rayon; and sheet-like substrates made of mixtures or laminates of these fibers.

[0057] <<Metal base material>> The metal substrate is not particularly limited, and examples thereof include sheet-like substrates made of metals such as iron, copper, aluminum, gold, platinum, and silver, as well as alloys or laminates of these metals.

[0058] <<Glass substrate>> The glass substrate is not particularly limited, and examples thereof include sheet-like substrates made of soda lime glass, borosilicate glass, alkali-free glass, quartz glass, and the like.

[0059] <Method for manufacturing self-adhesive foam laminate sheet> An example of a method for producing the laminate sheet of the present invention will now be described.

[0060] Fig. 1 shows a flowchart illustrating an example of a method S10 for producing a laminate sheet (hereinafter, sometimes abbreviated as "production method S10"). As shown in Fig. 1, production method S10 includes a composition preparation step S1, a foaming step S2, and a sheet formation step S3, in this order. Each step will be described below.

[0061] <<Composition preparation step S1>> The composition preparation step S1 is a step of preparing a composition for a self-adhesive foam sheet.

[0062] Specifically, in the composition preparation step S1, a foam sheet composition can be prepared by mixing the essential components of a polymer, a crosslinking agent, and a wax agent, as well as optionally using a solvent and other additives, by any method.

[0063] For example, when a polymer latex is used to prepare a foam sheet composition, the crosslinking agent, the wax agent, and other optional additives may be added to the polymer latex and mixed by a known method. When a solid polymer is used without using a solvent to prepare a foam sheet composition, the solid polymer, the crosslinking agent, the wax agent, and other optional additives may be mixed by a known method (for example, using a known roll, Henschel mixer, kneader, etc.).

[0064] Here, the viscosity of the solvent-containing foam sheet composition (e.g., in the form of an emulsion or dispersion) is preferably 1,000 mPa·s or more and 10,000 mPa·s or less, more preferably 2,000 mPa·s or more and 10,000 mPa·s or less, and even more preferably 3,500 mPa·s or more and 5,500 mPa·s or less. A foam sheet composition with a viscosity of 1,000 mPa·s or more can prevent dripping and difficulty in controlling thickness when a foam formed from the foam sheet composition is coated on a substrate to form a foam sheet. On the other hand, a foam sheet composition with a viscosity of 10,000 mPa·s or less can prevent difficulty in controlling the expansion ratio by mechanical foaming when forming a foam sheet. The viscosity of the foam sheet composition can be measured by the method described in the Examples of this specification.

[0065] <<Foaming process S2>> The foaming step S2 is a step of foaming the composition for a foam sheet to obtain a foam of the composition for a foam sheet.

[0066] Specifically, in the foaming step S2, the foamed sheet composition prepared in the composition preparation step S1 is foamed to obtain a foam in an unsolidified (uncrosslinked) state. When the foamed sheet composition is in the form of an emulsion or dispersion, a foamed emulsion or foamed dispersion is obtained.

[0067] Mechanical foaming is usually used as the foaming method. The foaming ratio may be adjusted as appropriate, but is usually 1.2 to 5 times, preferably 1.5 to 4 times. The mechanical foaming method is not particularly limited, but can be carried out by mixing a certain amount of air into the emulsion or dispersion of the foam sheet composition and stirring it continuously or batchwise using an oak mixer, whipper, or the like. The foamed emulsion or foamed dispersion obtained in this manner is creamy. By forming pores by the mechanical foaming, a foamed sheet with excellent air release properties can be obtained through the sheeting step S3 described below. An expansion ratio of 1.2 times or more can prevent a decrease in air release properties, while an expansion ratio of 5 times or less can prevent a decrease in the strength of the foamed sheet.

[0068] <<Sheeting process S3>> The sheet forming step S3 is a step of forming the foam into a sheet and then carrying out a crosslinking reaction of the foam to produce a foam sheet.

[0069] In the sheeting step S3, the method for forming the foam produced in the foaming step S2 into a sheet is not particularly limited. A suitable method includes, for example, coating the foam onto a desired substrate and forming it into a sheet. By coating the foam onto the desired substrate in this manner and allowing the crosslinking reaction to proceed, a laminated sheet can be obtained in which a foam sheet is provided directly on the substrate.

[0070] The foam coating can also be performed on a release sheet (such as releasable casting paper) instead of the substrate. By coating the foam on the release sheet and allowing the crosslinking reaction to proceed, a laminate can be obtained in which the foam sheet is directly provided on the release sheet. The release sheet can then be peeled off from the foam sheet of this laminate, yielding the foam sheet alone (as an independent film).

[0071] As a method for coating the foam onto a substrate or a release sheet (hereinafter, these may be collectively referred to as "substrate, etc."), a commonly known coating device such as an applicator, bar coater, roll coater, reverse roll coater, screen coater, doctor knife coater, or comma knife coater can be used.

[0072] A preferred method for crosslinking a foam coated in a sheet form on a substrate or the like is to heat-dry the foam. The heat-drying method is not particularly limited as long as it is a method that can dry and crosslink a foam coated on a substrate or the like, and a known drying oven (e.g., a hot air circulating oven, a hot oil circulating hot air chamber, or a far-infrared heater chamber) can be used. The drying temperature can be, for example, 60°C or higher and 180°C or lower. Furthermore, rather than drying at a constant temperature, it is preferable to perform multi-stage drying in which drying is performed from the inside at a low temperature in the early stages of drying and then sufficient drying at a higher temperature in the later stages of drying.

[0073] The properties of the foamed sheet (density, thickness, hardness, etc.) can be adjusted by, for example, changing the mixing ratio of air bubbles, the composition of the foamed sheet composition, the solid content concentration, the drying and crosslinking conditions, etc.

[0074] The laminated sheet obtained through the above-described steps S1 to S3 can be processed into a convenient size by, for example, applying a separator film to the self-adhesive surface (i.e., the surface on the foamed sheet side), winding it up with a winder, and cutting it with a press cutter, slitter, or the like, without any particular limitation.

[0075] <Applications of laminated sheets> The substrate surface of the laminate sheet of the present invention can be printed using, for example, offset printing, seal printing, flexographic printing, silk screen printing, gravure printing, a laser printer, a thermal transfer printer, an inkjet printer, or the like. Laminated sheets with printing on the substrate surface can be advantageously used for outdoor applications such as sales promotion cards, so-called POP cards (posters, stickers, displays, etc.), gardening POP (insertion labels, etc.), road signs (for funerals, home exhibitions, etc.), and signboards (for no trespassing, forest road work, etc.). [Example]

[0076] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples. In the following description, "%" and "parts" representing amounts are based on mass unless otherwise specified. In addition, in a polymer produced by polymerizing multiple types of monomers, the proportion of a monomer unit formed by polymerizing a certain monomer in the polymer usually corresponds to the ratio (feed ratio) of that certain monomer to all the monomers used in the polymerization of the polymer, unless otherwise specified. In the examples and comparative examples, the glass transition temperature and gel fraction of the polymer, the viscosity of the foam sheet composition, the density of the foam sheet, and the air release properties (initial and after heating and pressing) and formaldehyde emission amount of the laminate sheet were evaluated by the following methods.

[0077] <Glass transition temperature of polymer> The glass transition temperature (Tg) of the polymer used as the material for the self-adhesive foam laminate sheet was measured using the following method. A polymer latex containing the polymer was applied to a 50 μm-thick polyethylene terephthalate film using a 250 μm applicator and dried at room temperature for 24 hours to obtain a film formed on the polyethylene terephthalate film. The glass transition temperature (°C) of the film formed on this polyethylene terephthalate film (other than the polyethylene terephthalate film) was measured using a differential scanning calorimeter (manufactured by Hitachi High-Tech Science Corporation, product name "DSC7000X") in accordance with JIS K 7121 under the conditions of a measurement temperature of -50°C to 160°C and a heating rate of 10°C / min. <Gel fraction of polymer> The gel fraction of the polymer used in the laminate sheet was measured using the following method. The polymer was applied to a 50 μm-thick polyethylene terephthalate (PET) film using a 250 μm applicator and dried at room temperature for 24 hours to obtain a resin film. A predetermined amount (X) (approximately 500 mg) of this film was precisely weighed and immersed in 100 ml of ethyl acetate at room temperature for 3 days. The insoluble matter was then filtered through a 200-mesh wire screen, air-dried at room temperature for 15 hours, dried at 100°C for 2 hours, and cooled at room temperature. The weight (Y) of the sample was then measured. The gel fraction was calculated by substituting X and Y into the following equation: Gel fraction (%) = (Y) / (X) × 100 <Viscosity of the foam sheet composition> The viscosity of the foam sheet composition was measured at 23°C using a Brookfield viscometer (manufactured by Rion Co., Ltd., product name "VISCOTESTER VT-06"). <Foam sheet density> After preparing the laminate sheet, a test piece was cut to a size of 20 cm x 20 cm. The mass of the cut test piece (Vg) was precisely weighed, and the mass of the substrate cut to a 20 cm x 20 cm size (Wg) was also precisely weighed. The thicknesses of the prepared laminate sheet and substrate were then measured using a thickness gauge, and the thickness of the substrate was subtracted from the thickness of the laminate sheet to obtain the thickness of the foam sheet (Tcm). The thickness value was calculated from the average value of measurements taken at six points. The density of the foam sheet was calculated by substituting the measured values ​​of V, W, and T into the following equation. Density (g / cm 3 )=(VW) / (T×20×20) <Air release> <<Evaluation equipment>> The air release property was evaluated using an evaluation device 100 shown in Fig. 2. The evaluation device 100 shown in Fig. 2 is an apparatus for evaluating the air release property of a laminated sheet 50 formed by laminating a foamed sheet 51 and a substrate 52, and includes a sample fixing plate 10 having through-holes 11 and a gas pressure-feeding mechanism 40 that pressure-feeds air as a gas at a constant pressure from the other surface side (the upper side in Fig. 2) of the sample fixing plate 10 to one surface side (the lower side in Fig. 2) through the through-holes 11. Here, the gas pressure-feeding mechanism 40 has a syringe 20 whose tip is connected to the through-hole 11 of the sample fixing plate 10 on the other surface side of the sample fixing plate 10, and a weight 30. The syringe 20 is connected to the sample fixing plate 10 with its tip facing vertically downward (downward in FIG. 2), and is equipped with a needle 21 inserted into and fixed in the through-hole 11 of the sample fixing plate 10, a cylindrical outer tube 22 whose tip (the lower end in FIG. 2) is connected to the through-hole 11 via the needle 21, and a piston 23 inserted into the outer tube 22 from the rear end side. The weight 30 is attached to a flange provided at the rear end of the piston 23 (the upper end in FIG. 2). Furthermore, in the gas pressure-transfer mechanism 40 having the above-described configuration, the piston 23 is pushed into the outer tube 22 by the weight of the piston 23 and the weight 30, and the air inside the outer tube 22 is pressure-transferred at a constant pressure to one surface side (foam sheet 51) of the sample fixing plate 10 through the needle 21 and the through-hole 11. In the evaluation device 100 having the above-described configuration, for example, after attaching the laminate sheet 50 to one surface (the side opposite to the needle 21) of the sample fixing plate 10 to which the needle 21 is fixed so as to cover the through-hole 11 (step (A)), an outer cylinder 22 having a piston 23 attached thereto and inserted to a position at a distance L from the tip thereof is connected to the needle 21, and the time required for the piston 23 to move the distance L under the weight of the piston 23 and weight 30 is measured (step (B)), thereby enabling the air release property of the laminate sheet 50 to be evaluated. That is, since the air in the outer cylinder 22 is pushed out of the through-hole 11 with a constant pressure due to the weight of the piston 23 and weight 30, if the distance L and the amount of air pushed out from the outer cylinder 22 are kept constant, the laminate sheet 50 with poorer air release property will take a longer time to move the distance L, and the laminate sheet 50 with higher air release property will take a shorter time to move the distance L. Therefore, the air release property of the laminate sheet 50 can be quantitatively evaluated based on the time required for the piston 23 to move the distance L. Moreover, since the evaluation can be performed under conditions where the amount and pressure of the compressed air are constant, the air release property can be evaluated with high repeatability. Furthermore, since the evaluation can be performed while the laminate sheet 50 is attached to the sample fixing plate 10, the air release property of the laminate sheet 50 when attached to the adherend can be accurately evaluated. The sample fixing plate 10 was a 1 mm thick transparent polycarbonate plate (50 mm x 50 mm), the syringe 20 was a 2 mL glass syringe with a 2 mm diameter metal syringe needle, and the weight 30 was a 30 g weight attached to the piston 23 with double-sided tape. <<Evaluation of air release (initial stage)>> After the laminate sheet was produced, it was cut into a size of 40 mm x 40 mm to be used as a sample to be evaluated. The foamed sheet side of the prepared sample was then attached to one surface (opposite the needle 21 side) of the sample fixing plate 10 to which the needle 21 was fixed, covering the through-hole 11 and preventing air from entering (step (A)). Then, an outer cylinder 22, with a piston 23 attached to a weight 30 inserted up to the 2 mL mark, was connected to the needle 21. The weight 30 and piston 23 were then released, and the time required for the piston 23 and weight 30 to fall completely under their own weight (i.e., until 2 mL of air was pumped out) was measured (step (B)). This measurement procedure was repeated three times, and the average of the measured times was calculated and evaluated according to the following criteria. A smaller average value indicates better air release properties (initial) of the laminated sheet. A: The average measurement time is 10 seconds or less B: The average measured time is more than 10 seconds and less than 20 seconds C: The average measured time is more than 20 seconds and less than 30 seconds D: The average measured time is over 30 seconds <<Evaluation of air release (after heating and pressurization)>> The laminated sheet was cut into a size of 80 mm x 120 mm and then subjected to a 110 g / cm 2 A pressure of 1000 kJ / cm was applied and the laminate was left for 24 hours. The pressure was then released under conditions of 23°C and 50% RH, and the laminate was left to stand for 24 hours. The laminate was then cut into pieces measuring 40 mm x 40 mm, which were used as samples for evaluation. Except for this, measurements and evaluation were carried out in the same manner as in "Evaluation of air release properties (initial)." The smaller this average value, the better the air release properties (after heating and pressurization) of the laminate sheet. <Formaldehyde emission amount> A self-adhesive foam sheet was prepared, and a separator film was attached to the surface of the foam layer (adsorption layer). A 200mm x 200mm test piece was then cut into the sheet. The test piece was placed in a 5L Tedlar bag and sealed. 2L of air was then sealed inside the bag, and the bag was left in a thermostatic chamber set at 23°C and 50% RH for 6 hours. The formaldehyde concentration inside the bag was measured using a detector tube (Gastec Corporation, No. 91L). A formaldehyde concentration of 0.1 ppm or less was rated "A," and a concentration above 0.1 ppm was rated "B."

[0078] Example 1 <Preparation of Polymer> A monomer mixture consisting of 64 parts of ethyl acrylate, 12 parts of 2-ethylhexyl acrylate, 12 parts of n-butyl acrylate, 9 parts of acrylonitrile, 2 parts of styrene, and 1 part of acrylic acid, and 0.4 parts of sodium polyoxyethylene alkyl sulfate (manufactured by Kao Corporation: product name "Latemul E-118B") were mixed and stirred with 27.0 parts of deionized water to obtain a monomer emulsion. Next, a separate glass reactor equipped with a reflux condenser, dropping funnel, thermometer, nitrogen inlet, and stirrer was prepared. 43.0 parts of deionized water and 0.2 parts of polyoxyethylene alkyl sodium sulfate were added to the glass reactor, and the temperature was raised to 80°C while stirring. While maintaining the temperature at 80°C, 0.3 parts of ammonium persulfate dissolved in 5.7 parts of deionized water was added, followed by the slow addition of the monomer emulsion obtained above over a period of 4 hours. After the addition was completed, stirring was continued for another 4 hours, and the mixture was cooled to terminate the reaction, yielding a reaction mixture. The polymerization conversion rate at this point was nearly 100% (98% or higher). The resulting reaction mixture was adjusted to pH 5.0 with 5% aqueous ammonia, and 2.5 parts of polyoxyethylene lauryl ether (Kao Corporation: product name "Emulgen 120") was added. The mixture was then concentrated to yield a polymer latex with a solids concentration of 55%. The glass transition temperature and gel fraction of the polymer contained in the resulting polymer latex were measured. The results are shown in Table 1. <Preparation of foam sheet composition> To a mixing vessel were added, in this order, 100 parts of the polymer latex (i.e., 55 parts of the polymer contained in the polymer latex), 3 parts of an epoxy-based crosslinker (manufactured by Japan Coating Resins Co., Ltd., product name "Rikabond EX-8", fatty acid polyglycidyl ether), 2 parts of a wax agent (containing a fatty acid ester having a fatty acid moiety having 16 to 34 carbon atoms), and 4 parts of a foam stabilizer [ammonium stearate (manufactured by San Nopco Ltd., product name "Nopco DC-100A")]. Finally, a thickener [sodium polyacrylate (manufactured by Toagosei Co., Ltd., product name "Aron A-20L")] was added to adjust the viscosity to 4250 mPa s, yielding a foam sheet composition. <Production of laminated sheets> The foam sheet composition obtained as described above was stirred with a whisk to foam the composition to an expansion ratio of 1.6 times, and the stirring speed was further reduced and stirring was continued for 5 minutes. The foamed foam sheet composition (foam) was coated onto a substrate (a 50 μm-thick sheet substrate made of polyethylene terephthalate) using a 0.3 mm applicator. The coated substrate was placed in a drying oven and held at 80°C for 1.33 minutes, 120°C for 1.33 minutes, and 140°C for 1.33 minutes for drying and crosslinking to obtain a laminate sheet comprising a foam sheet on a substrate. The thickness of the dried foam sheet was 0.140 mm. Various evaluations were performed using the resulting laminate sheet. The results are shown in Table 1.

[0079] Example 2 A foam sheet composition and a laminate sheet were prepared or produced in the same manner as in Example 1, except that the polymer prepared as follows was used. Evaluations were then carried out in the same manner as in Example 1. The results are shown in Table 1. <Preparation of Polymer> A monomer mixture consisting of 56 parts of ethyl acrylate, 15 parts of 2-ethylhexyl acrylate, 18 parts of n-butyl acrylate, 8 parts of acrylonitrile, 2 parts of styrene, and 1 part of acrylic acid, and 0.4 parts of polyoxyethylene alkyl sodium sulfate (manufactured by Kao Corporation: product name "Latemul E-118B") were mixed and stirred with 27.0 parts of deionized water to obtain a monomer emulsion. Except for this, a polymer latex was obtained in the same manner as in Example 1.

[0080] (Comparative Example 1) <Preparation of Polymer> A monomer mixture consisting of 46.9 parts ethyl acrylate, 45.8 parts n-butyl acrylate, 5.9 parts acrylonitrile, and 1.4 parts N-methylolacrylamide was mixed with 27.0 parts deionized water and stirred with 0.4 parts polyoxyethylene alkyl sodium sulfate (manufactured by Kao Corporation: product name "Latemul E-118B") to obtain a monomer emulsion. A polymer latex was obtained in the same manner as in Example 1, except for the above. Evaluations were then carried out in the same manner as in Example 1. The results are shown in Table 1. <Preparation of foam sheet composition> The polymer latex obtained as described above was used, and the amount of crosslinking agent added was changed from 3 parts to 3.6 parts (i.e., 6.5 parts of crosslinking agent per 100 parts of polymer). Furthermore, no wax agent was added. A foam sheet composition was prepared in the same manner as in Example 1. <Production of laminated sheets> The expansion ratio was changed from 1.6 to 2, and the foam sheet composition obtained as described above was used. Except for this, a laminate sheet was produced in the same manner as in Example 1. Evaluations were then carried out in the same manner as in Example 1. The results are shown in Table 1.

[0081] (Comparative Example 2) <Preparation of Polymer> A monomer mixture consisting of 70 parts of n-butyl acrylate, 14 parts of methyl methacrylate, 14 parts of styrene, and 2 parts of itaconic acid, and 0.4 parts of polyoxyethylene alkyl sodium sulfate (manufactured by Kao Corporation: product name "Latemul E-118B") were mixed and stirred with 27.0 parts of deionized water to obtain a monomer emulsion. Except for this, a polymer latex was obtained in the same manner as in Example 1. Evaluations were then carried out in the same manner as in Example 1. The results are shown in Table 1. <Preparation of foam sheet composition> The polymer latex obtained as described above was used, and the amount of crosslinking agent added was changed from 3 parts to 3.6 parts (i.e., 6.5 parts of crosslinking agent per 100 parts of polymer). Furthermore, no wax agent was added. A foam sheet composition was prepared in the same manner as in Example 1. <Production of laminated sheets> Except for using the foam sheet composition obtained as described above, a laminate sheet was produced in the same manner as in Example 1. Evaluations were then carried out in the same manner as in Example 1. The results are shown in Table 1.

[0082] In addition, in Table 1 shown below, "EA" represents an ethyl acrylate unit; "MMA" indicates a methyl methacrylate unit, "2EHA" indicates a 2-ethylhexyl acrylate unit, "BA" represents an n-butyl acrylate unit; "AA" represents an acrylic acid unit; "IA" indicates an itaconic acid unit; "AN" indicates an acrylonitrile unit; "ST" indicates a styrene unit; "NMA" indicates an N-methylolacrylamide unit; "Tg" indicates the glass transition temperature.

[0083] [Table 1]

[0084] Table 1 shows that in Examples 1 and 2, which used foam sheet compositions containing a polymer, a crosslinking agent, and a wax agent, laminate sheets with excellent air release properties after heating and pressurizing could be formed. On the other hand, it is clear that in Comparative Examples 1 and 2, in which a foamable sheet composition containing no wax agent was used, a laminate sheet having excellent air release properties after heating and pressurizing could not be formed. [Industrial Applicability]

[0085] According to the present invention, it is possible to provide a self-adhesive foam laminate sheet that has excellent air release properties after heating and pressurizing, and a composition for a self-adhesive foam sheet that can be used to obtain the self-adhesive foam laminate sheet. [Explanation of symbols]

[0086] S1 Composition preparation process S2 Foaming process S3 Sheeting process S10 Method for manufacturing laminated sheets 10. Sample fixing plate 11 Through hole 20 syringes 21 needles 22 Outer cylinder 23 Piston 30 weights 40 Gas pumping mechanism 50 laminated sheets 51 Foam Sheet 52 Base material 100 Evaluation Device

Claims

1. comprising a polymer, a crosslinker, and a wax agent; the polymer contains, relative to 100 mass% of all repeating units contained in the polymer, 60 mass% to 95 mass% of (meth)acrylate monomer units, 0.1 mass% to 10 mass% of unsaturated carboxylic acid monomer units, 1 mass% to 30 mass% of vinyl cyanide monomer units, and 0.5 mass% to 20 mass% of alkenyl aromatic monomer units; The wax agent is a composition for a self-adsorbing foam sheet, which comprises a fatty acid ester having a fatty acid moiety having 16 to 34 carbon atoms.

2. 2. The composition for a self-adhesive foam sheet according to claim 1, wherein the polymer does not have an N-methylol group.

3. 3. The composition for a self-adsorbing foam sheet according to claim 1, wherein the amount of the fatty acid ester blended is 0.5 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the polymer.

4. 4. The composition for a self-adsorbing foam sheet according to claim 1, wherein the fatty acid ester has an alcohol moiety having 30 to 34 carbon atoms.

5. A self-adhesive foam laminate sheet comprising a substrate and a self-adhesive foam sheet formed using the composition for a self-adhesive foam sheet according to any one of claims 1 to 4, A self-adhesive foam laminate sheet, wherein the substrate is a paper substrate other than a synthetic paper substrate, a plastic substrate, a fiber substrate, a metal substrate, or a glass substrate.

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