Emulsion, fine particles, and resin composition

Abstract

Provided is an emulsion containing, as a dispersoid, a (meth)acrylic acid ester polymer comprising, as a monomer unit constituting the polymer, an ethylene carbonate-containing acrylic monomer that has an ethylene carbonate structure represented by formula (1). By using this emulsion, a novel emulsion that uses carbon dioxide as a production starting material, and an article that comprises a resin film formed from an emulsion composition are provided.

Description

Emulsion, fine particles and resin composition

[0001] In a first aspect, the present invention relates to emulsions and articles made with the emulsions.

[0002] In a second aspect, the present invention relates to microparticles, resin compositions containing the microparticles, and articles made using the resin compositions.

[0003] In a third aspect, the present invention relates to a resin composition, a resin film formed from the resin composition, an article including the resin film, and a method for separating components constituting the article.

[0004] Regarding the first aspect, in recent years, from the viewpoint of environmental consideration, there has been a demand for electronic devices, electrical appliances, etc. that can be easily disassembled when they are no longer needed (easy disassembly). The parts generated by disassembly can be recycled or reused.

[0005] For example, when components constituting a product are bonded together with an adhesive sheet, the adhesiveness of the adhesive sheet is reduced by an external stimulus, thereby facilitating separation and peeling of the components. As an example of such an adhesive sheet, Patent Document 1 discloses an adhesive sheet made of a water-soluble adhesive that can be disassembled and peeled by immersion in water. Furthermore, Patent Document 2 discloses a heat-foamable, removable adhesive tape that maintains high adhesive strength in its normal state when bonded, but reduces its adhesive strength by heating when separating or dismantling the bonded portion, allowing for easy separation and dismantling.

[0006] Regarding the second aspect, organic fine particles are used in a wide range of applications, such as as an antiblocking agent, a toner additive, a powder coating material, a water-dispersible coating material, a decorative plate additive, an artificial marble additive, a cosmetic filler, a chromatography column filler, a matting agent, and the like, in resin films, coating materials, adhesives, pressure-sensitive adhesives, and the like.

[0007] In recent years, from the viewpoint of environmental consideration, there has been a demand for electronic devices, electrical appliances, etc. that can be easily disassembled when they are no longer needed (easy disassembly). The parts that are generated by disassembly can be recycled or reused.

[0008] For example, when components constituting a product are bonded together with an adhesive sheet, the adhesiveness of the adhesive sheet is reduced by an external stimulus, thereby facilitating separation and peeling of the components. As an example of such an adhesive sheet, Patent Document 2 discloses a heat-expandable, removable adhesive tape that maintains high adhesive strength in a normal state when bonded, but reduces its adhesive strength when heated when separating or dismantling the bonded parts, allowing for easy separation and dismantling.

[0009] Regarding the third aspect, in recent years, from the viewpoint of environmental consideration, there has been a demand for electronic devices, electrical appliances, etc. that can be easily disassembled when they are no longer needed (easy disassembly). The parts generated by disassembly can be recycled or reused.

[0010] For example, when components constituting a product are bonded together with an adhesive sheet, the adhesiveness of the adhesive sheet is reduced by an external stimulus, thereby facilitating separation and peeling of the components. As an example of such an adhesive sheet, Patent Document 1 discloses an adhesive sheet made of a water-soluble adhesive that can be disassembled and peeled by immersion in water. Furthermore, Patent Document 2 discloses a heat-foamable, removable adhesive tape that maintains high adhesive strength in its normal state when bonded, but reduces its adhesive strength by heating when separating or dismantling the bonded portion, allowing for easy separation and dismantling.

[0011] JP 2023-35332 A JP 2014-214208 A

[0012] Regarding the first aspect, when dismantling a product using the adhesive sheet disclosed in Patent Document 1, it is necessary to bring at least the adhesive sheet portion into contact with water. However, if the product is large or if the adhesive sheet is located deep inside the product and it is difficult for water to reach it, handling becomes difficult.

[0013] Furthermore, easy disassembly may be required even for products that do not use adhesive sheets, and in such cases, the adhesive sheet disclosed in Patent Document 1 cannot adequately meet the requirements.

[0014] The thermal blowing agent (particularly thermally expandable microspheres) disclosed in Patent Document 2 generally has an average particle size of about 1 to 80 μm in terms of dispersibility, thin layer formability, etc., which may not be sufficient for some applications of the PSA sheet.

[0015] Furthermore, in recent years, there has been an increasing demand for emulsion-type resin compositions due to legal regulations, environmental considerations, and the like.

[0016] In recent years, with the growing demand for the creation of a recycling-oriented society, gases such as carbon dioxide, methane, and carbon monoxide have been attracting attention as sustainable carbon raw materials. For example, it has been reported that copolymerization of carbon dioxide with epoxide can produce aliphatic polycarbonates with only aliphatic (non-aromatic) groups in the main chain, and there has been interest in chemical products and their manufacturing technologies that use gases such as carbon dioxide as raw materials. Carbon dioxide is considered to be a cause of global warming, so the effective use of carbon dioxide emitted from factories in the process of producing various materials will contribute to environmental protection.

[0017] Therefore, there is a need for a further option for emulsion-type resin compositions that use carbon dioxide as a manufacturing raw material and that enable easier handling and easier disassembly.

[0018] Regarding the first aspect, the present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a novel emulsion using carbon dioxide as a production raw material and an article having a resin film formed from the emulsion composition.

[0019] Regarding the second aspect, the average particle size of the thermal blowing agent (particularly, thermally expandable microspheres) disclosed in Patent Document 2 is generally about 1 to 80 μm in terms of dispersibility, thin layer formability, etc., which may not be sufficient for some applications of the PSA sheet.

[0020] Furthermore, easy disassembly may be required even for products that do not use adhesive sheets, and in such cases, the adhesive sheet disclosed in Patent Document 1 cannot adequately meet the requirements.

[0021] Furthermore, in recent years, with growing calls for the creation of a recycling-oriented society, gases such as carbon dioxide, methane, and carbon monoxide have been attracting attention as sustainable carbon raw materials. For example, it has been reported that copolymerization of carbon dioxide with epoxide can produce aliphatic polycarbonates, which have only aliphatic (non-aromatic) groups in their main chains. This has led to interest in chemical products and their manufacturing technologies that use gases such as carbon dioxide as raw materials. Carbon dioxide is considered to be a cause of global warming, so the effective use of carbon dioxide emitted from factories in the process of producing various materials will contribute to environmental protection.

[0022] Therefore, there is a need for further options for organic fine particles that use carbon dioxide as a manufacturing raw material and that are easier to handle and disassemble.

[0023] Regarding the second aspect, the present invention has been made in consideration of the above-mentioned circumstances, and aims to provide novel microparticles produced using carbon dioxide as a raw material, a resin composition containing the microparticles, and an article produced using the resin composition.

[0024] Regarding the third aspect, when dismantling a product using the adhesive sheet disclosed in Patent Document 1, it is necessary to bring at least the adhesive sheet portion into contact with water. However, if the product is large or if the adhesive sheet is located deep inside the product and it is difficult for water to reach it, handling becomes difficult.

[0025] Furthermore, easy disassembly may be required even for products that do not use adhesive sheets, and in such cases, the adhesive sheet disclosed in Patent Document 1 cannot adequately meet the requirements.

[0026] The thermal blowing agent (particularly thermally expandable microspheres) disclosed in Patent Document 2 generally has an average particle size of about 1 to 80 μm in terms of dispersibility, thin layer formability, etc., which may not be sufficient for some applications of the PSA sheet.

[0027] Furthermore, in recent years, due to legal regulations and environmental considerations, there has been growing interest in emulsion-type resin compositions and chemical products that use gases such as carbon dioxide, which are considered to be a cause of global warming, as raw materials. Therefore, there is a demand for further options that are environmentally friendly and enable easier handling and disassembly.

[0028] Regarding the third aspect, the present invention has been made in consideration of the above circumstances, and has an object to provide a new means for realizing easy disassembly.

[0029] In order to achieve the object of the first aspect, firstly, the present invention provides a polymer comprising a monomer unit represented by the following formula (1): The present invention provides an emulsion characterized by containing, as a dispersoid, a (meth)acrylic acid ester polymer containing an ethylene carbonate-containing acrylic monomer having an ethylene carbonate structure represented by the following formula (Invention 1).

[0030] In the emulsion according to the above invention (Invention 1), the ethylene carbonate structure present in the (meth)acrylic acid ester polymer can be produced using carbon dioxide as a raw material, thereby enabling the effective use of carbon dioxide. Furthermore, the ethylene carbonate structure decomposes when heated with a catalyst, releasing carbon dioxide. Therefore, even when a resin film (such as a pressure-sensitive adhesive layer) formed using the emulsion is in close contact with another object, the carbon dioxide accumulates at the interface between the resin film and the object, thereby reducing adhesion. As a result, the emulsion can be used to easily separate a resin film from an object.

[0031] In the above invention (Invention 1), the (meth)acrylic acid ester polymer preferably contains the ethylene carbonate-containing monomer as a monomer unit constituting the polymer in an amount of 1% by mass or more and 99.9% by mass or less (Invention 2).

[0032] In the above inventions (Inventions 1 and 2), the ethylene carbonate-containing acrylic monomer is preferably a compound represented by any one of the following formulas (2) to (4) (Invention 3). (In the formula, n represents an integer of 0 or more.) (In the formula, n represents an integer of 0 or more.) (In the formula, n and m represent integers of 0 or more. X represents hydrogen or a methyl group.)

[0033] In the above inventions (Inventions 1 to 3), the particle size (D50) of the dispersoid is preferably 10 nm or more and 1 μm or less (Invention 4).

[0034] In the above inventions (Inventions 1 to 4), the (meth)acrylic acid ester polymer preferably contains acrylic acid as a monomer unit constituting the polymer (Invention 5).

[0035] In the above inventions (Inventions 1 to 5), the (meth)acrylic acid ester polymer is preferably obtained by emulsion polymerization of monomer units containing the ethylene carbonate-containing acrylic monomer (Invention 6).

[0036] In the above inventions (Inventions 1 to 6), it is preferable that water is contained as the dispersion medium (Invention 7).

[0037] Secondly, the present invention provides an article (Invention 8) having a resin film formed from a resin composition containing the emulsion (Inventions 1 to 7).

[0038] In the above invention (Invention 8), it is preferable that the resin film is a pressure-sensitive adhesive layer and the article is a pressure-sensitive adhesive sheet (Invention 9).

[0039] In order to achieve the object of the second aspect, the present invention thirdly provides a polymer comprising a monomer unit represented by the following formula (1): The present invention provides fine particles containing a (meth)acrylic acid ester polymer containing an ethylene carbonate-containing acrylic monomer having an ethylene carbonate structure represented by the formula (Invention 10).

[0040] In the microparticles according to the invention (Invention 10), the ethylene carbonate structure present in the (meth)acrylic acid ester polymer can be produced using carbon dioxide as a raw material, thereby enabling the effective use of carbon dioxide. Furthermore, the ethylene carbonate structure decomposes when heated with a catalyst, releasing carbon dioxide. Therefore, even when a resin film (such as an adhesive layer) formed using the microparticles is in close contact with another object, the carbon dioxide accumulates at the interface between the resin film and the object, thereby reducing adhesion. As a result, the microparticles can be used to easily separate a resin film from an object.

[0041] In the above invention (Invention 10), the (meth)acrylic acid ester polymer preferably contains the ethylene carbonate-containing monomer in an amount of 50% by mass or more and 99.9% by mass or less as a monomer unit constituting the polymer (Invention 11).

[0042] In the above inventions (Inventions 10 and 11), the ethylene carbonate-containing acrylic monomer is preferably a compound represented by the following formula (2) or (3) (Invention 12). (In the formula, n represents an integer of 0 or more.) (In the formula, n represents an integer of 0 or more.)

[0043] In the above inventions (Inventions 10 to 12), the (meth)acrylic acid ester polymer preferably contains acrylic acid as a monomer unit constituting the polymer (Invention 13).

[0044] In the above inventions (Inventions 10 to 13), it is preferable that the average particle size is 10 nm or more and 1 μm or less (Invention 14).

[0045] In the above inventions (Inventions 10 to 14), it is preferable to obtain the (meth)acrylic acid ester polymer by emulsion polymerization of monomer units containing the ethylene carbonate-containing acrylic monomer to produce an emulsion containing the (meth)acrylic acid ester polymer as a dispersoid, and then removing the dispersion medium constituting the emulsion to obtain a residue, and pulverizing the residue (Invention 15).

[0046] Fourthly, the present invention provides a resin composition (Invention 16) containing the above-mentioned fine particles (Inventions 10 to 15).

[0047] Fifthly, the present invention provides an article (Invention 17) comprising a resin film formed from the resin composition (Invention 16).

[0048] In the above invention (Invention 17), it is preferable that the resin film is an adhesive layer and the article is an adhesive sheet (Invention 18).

[0049] In order to achieve the object related to the third aspect, the present invention sixthly provides a polymer comprising a monomer unit represented by the following formula (1): or a resin composition characterized by comprising: fine particles containing the (meth)acrylic acid ester polymer; and a catalyst capable of nucleophilic attack on carbon atoms constituting carbonyl groups in the ethylene carbonate structure, thereby decomposing the ethylene carbonate structure and releasing carbon dioxide (Invention 19).

[0050] In the resin composition according to the above invention (Invention 19), the ethylene carbonate structure present in the (meth)acrylic acid ester polymer decomposes by heat treatment under the action of the catalyst, releasing carbon dioxide. Therefore, even if a resin film (such as a pressure-sensitive adhesive layer) formed from the resin composition is in close contact with another object, the carbon dioxide accumulates at the interface between the resin film and the object, thereby reducing adhesion. As a result, the resin film can be easily separated from the object.

[0051] In the above invention (Invention 19), it is preferable that the particle diameter (D50) of the dispersoid is 10 nm or more and 1 μm or less, and the average particle diameter of the fine particles is 10 nm or more and 1 μm or less (Invention 20).

[0052] In the above inventions (Inventions 19 and 20), the (meth)acrylic acid ester polymer preferably contains the ethylene carbonate-containing monomer as a monomer unit constituting the polymer in an amount of 10% by mass or more and 99.9% by mass or less (Invention 21).

[0053] In the above inventions (Inventions 19 to 21), the ethylene carbonate-containing acrylic monomer is preferably a compound represented by the following formula (2) or (3) (Invention 22). (In the formula, n represents an integer of 0 or more.) (In the formula, n represents an integer of 0 or more.)

[0054] In the above inventions (Inventions 19 to 22), the catalyst is a nucleophilic anion generator capable of generating nucleophilic anions, and the nucleophilic anions are fluoride ions (F － ), chloride ions (Cl － ), bromide ion (Br － ), iodide ion (I － ) and hydroxide ions (OH － ) is preferably at least one of the following (Invention 23).

[0055] In the above inventions (Inventions 19 to 23), the catalyst is preferably at least one of tetrabutylammonium bromide and tetra-N-butylammonium fluoride (Invention 24).

[0056] In the above inventions (Inventions 19 to 24), the (meth)acrylic acid ester polymer preferably contains acrylic acid as a monomer unit constituting the polymer (Invention 25).

[0057] In the above inventions (Inventions 19 to 25), the (meth)acrylic acid ester polymer is preferably obtained by emulsion polymerization of a monomer unit containing the ethylene carbonate-containing acrylic monomer (Invention 26).

[0058] In the above inventions (Inventions 19 to 26), the fine particles are preferably obtained by emulsion polymerizing monomer units containing the ethylene carbonate-containing acrylic monomer to produce an emulsion containing the (meth)acrylic acid ester polymer as a dispersoid, and then removing the dispersion medium constituting the emulsion, and pulverizing the resulting residue (Invention 27).

[0059] In a seventh aspect, the present invention provides a resin film (Invention 28) formed from the resin composition (Inventions 19 to 27).

[0060] Eighth, the present invention provides an article comprising the resin film (Invention 28) and a member provided on at least one surface of the resin film (Invention 29).

[0061] A ninth invention provides a separation method for separating the resin film and the member in the article (Invention 29), the separation method comprising the steps of: heating the resin film to decompose the ethylene carbonate structure and generate carbon dioxide gas; and separating the resin film and the member by the carbon dioxide gas accumulated at the interface between the resin film and the member (Invention 30).

[0062] The emulsion of the first aspect of the present invention has a low environmental impact because it uses carbon dioxide as a raw material for production. Furthermore, the emulsion of the present invention decomposes when heated with a catalyst, releasing carbon dioxide, providing a new means for realizing easy dismantling.

[0063] The microparticles according to the second aspect of the present invention have a low environmental impact because they are produced using carbon dioxide as a raw material. Furthermore, the microparticles according to the present invention decompose when heated with a catalyst, releasing carbon dioxide, providing a new means for realizing easy dismantling by blending them into various resins.

[0064] The resin composition according to the third aspect of the present invention provides a new means for realizing easy dismantling.

[0065] 10 is a SEM image of the microparticles produced as Example 1 of the second aspect. FIG. 11 is a diagram showing the state of foaming after heating and the state of peeling of the sample for confirming dismantling property according to the example of the third aspect.

[0066] [First Aspect] Hereinafter, an embodiment of the first aspect of the present invention will be described. [Emulsion] The emulsion according to this embodiment contains, as a monomer unit constituting a polymer, a monomer represented by the following formula (1): The (meth)acrylic acid ester polymer contains, as a dispersoid, an ethylene carbonate-containing acrylic monomer having an ethylene carbonate structure represented by the formula:

[0067] The ethylene carbonate structure can release carbon dioxide by decomposition. In particular, when a nucleophilic anion is present together with the ethylene carbonate structure, the anion performs a nucleophilic attack on the carbon atom constituting the carbonyl group in the ethylene carbonate structure, thereby efficiently decomposing the ethylene carbonate structure and releasing carbon dioxide.

[0068] By using the emulsion according to the present embodiment, which has these properties, it is possible to manufacture products with excellent dismantling properties. That is, the carbon dioxide released from the emulsion can be used to reduce the adhesion between components constituting the product, thereby making it possible to easily dismantle the product. For example, when components are bonded together using a pressure-sensitive adhesive sheet manufactured using the emulsion as one of its materials, carbon dioxide can be generated by decomposition of the ethylene carbonate structure described above, and the carbon dioxide can be accumulated at the interface between the pressure-sensitive adhesive sheet and the components, allowing the pressure-sensitive adhesive sheet and the components to be physically separated.

[0069] The nucleophilic anions are preferably generated from a nucleophilic anion generator capable of generating nucleophilic anions in response to a predetermined stimulus. In particular, when a nucleophilic anion generator that generates the anions in response to heating is used, products using the emulsion according to the present embodiment can be disassembled by applying heat as an external stimulus.

[0070] 1. (Meth)acrylic Acid Ester Polymer The (meth)acrylic acid ester copolymer of the present embodiment is not particularly limited as long as it contains, as a monomer unit constituting the polymer, an ethylene carbonate-containing acrylic monomer having an ethylene carbonate structure represented by the above formula (1).

[0071] The ethylene carbonate-containing acrylic monomer is not particularly limited as long as it contains an ethylene carbonate structure and has a (meth)acryloyl group (structure). A preferred example of the ethylene carbonate-containing acrylic monomer is a (meth)acrylic acid ester having a structure in which an organic group having an ethylene carbonate structure and a (meth)acryloyloxy group are bonded. An example of such a (meth)acrylic acid ester is represented by the following formula (2): an acrylic acid ester represented by the following formula (3): or a methacrylic acid ester represented by the following formula (4): In any of formulas (2) to (4), n and m represent integers of 0 or more, and X represents hydrogen or a methyl group.

[0072] Among the (meth)acrylic acid esters represented by the above formulas (2) to (4), from the viewpoint of facilitating the release of carbon dioxide gas, (meth)acrylic acid esters in which n and m are each 1 or greater are preferred, and (meth)acrylic acid esters in which n and m are each 2 or greater are preferred. While the upper limit of each of the above n and m is not particularly limited, from the viewpoint of polymerizability, it is preferably 10 or less, more preferably 6 or less, particularly preferably 4 or less, and even more preferably 3 or less. Among these, (meth)acrylic acid esters in which n = 1 are preferred, and (2-oxo-1,3-dioxolan-4-yl)methyl methacrylate in which n = 1 in formula (3) is particularly preferred. The ethylene carbonate-containing monomers may be used singly or in combination of two or more.

[0073] As disclosed in JP-A-2006-335971, the ethylene carbonate-containing monomer is a compound that reacts with the epoxy group of a (meth)acrylate having an epoxy group by CO ion bonding. ２ That is, the (meth)acrylic acid ester copolymer according to the present embodiment, which uses an ethylene carbonate-containing monomer, can be produced using carbon dioxide as a production raw material, thereby enabling the effective use of carbon dioxide.

[0074] The (meth)acrylic acid ester copolymer of this embodiment preferably contains 1% by mass or more of the ethylene carbonate-containing acrylic monomer, more preferably 5% by mass or more, and even more preferably 10% by mass or more. Furthermore, the (meth)acrylic acid ester copolymer of this embodiment preferably contains 99.9% by mass or less of the ethylene carbonate-containing acrylic monomer, particularly preferably 99.5% by mass or less, and even more preferably 99.0% by mass or less. A content of 99.9% by mass or less ensures that the (meth)acrylic acid ester copolymer contains sufficient other constituent monomers, making it easier for the (meth)acrylic acid ester copolymer to exhibit the desired performance. When the emulsion of this embodiment is used as a base component to form a pressure-sensitive adhesive layer, the content of the ethylene carbonate-containing acrylic monomer is preferably, for example, 1% by mass or more and 30% by mass or less, from the viewpoint of obtaining properties usable as a pressure-sensitive adhesive layer. Furthermore, from the viewpoint of effectively using carbon dioxide as a production raw material, the content of the (meth)acrylic acid ester copolymer in this embodiment is preferably 90% by mass or more and 99.9% by mass or less.

[0075] The (meth)acrylic acid ester copolymer of this embodiment may contain, as a monomer unit constituting the polymer, a monomer other than the above-mentioned ethylene carbonate-containing acrylic monomer. Examples of such monomers include (meth)acrylic acid alkyl esters having an alkyl group containing 1 to 12 carbon atoms; monomers containing a reactive functional group such as a hydroxy group, a carboxy group, or an amino group; alkoxyalkyl group-containing (meth)acrylic acid esters; (meth)acrylic acid esters having an aromatic ring such as phenyl (meth)acrylate; non-crosslinkable acrylamides such as acrylamide and methacrylamide; (meth)acrylic acid esters having a non-crosslinkable tertiary amino group such as N,N-dimethylaminoethyl (meth)acrylate and N,N-dimethylaminopropyl (meth)acrylate; vinyl acetate; and styrene. These may be used alone or in combination of two or more.

[0076] Among the above, the (meth)acrylic acid ester copolymer in the present embodiment preferably contains, as a monomer unit constituting the polymer, acrylic acid, which corresponds to a monomer containing a carboxy group. When the (meth)acrylic acid ester copolymer contains acrylic acid, it becomes easy to adjust the particle size of the (meth)acrylic acid ester copolymer as a dispersoid.

[0077] When the (meth)acrylic acid ester copolymer of this embodiment contains a monomer other than the above-described ethylene carbonate-containing acrylic monomer as a monomer unit constituting the polymer, the content thereof is preferably 0.1% by mass or more, particularly preferably 0.3% by mass or more, and even more preferably 0.5% by mass or more. Furthermore, the content is preferably 99% by mass or less, particularly preferably 98% by mass or less, and even more preferably 97% by mass or less. This makes it easy to adjust the particle size of the (meth)acrylic acid ester copolymer as a dispersoid while ensuring a sufficient amount of the above-described ethylene carbonate structure in the (meth)acrylic acid ester copolymer.

[0078] In the emulsion according to this embodiment, the particle size (D50) of the dispersoid composed of the (meth)acrylic acid ester copolymer is preferably 10 nm or more, more preferably 30 nm or more, particularly preferably 50 nm or more, and even more preferably 100 nm or more. Furthermore, the particle size (D50) is preferably 1 μm or less, particularly preferably 0.8 μm or less, and even more preferably 0.6 μm or less. By having the particle size (D50) of the dispersoid within the above range, it becomes easier to form a resin film that can release carbon dioxide well while also having other desired properties. Details of the method for measuring the particle size (D50) are as described in the Examples below.

[0079] When the emulsion according to this embodiment has a (meth)acrylic acid ester copolymer content of 90% by mass or more and a dispersoid particle size (D50) of 100 nm or more, it exhibits a structural color of any color resulting from Bragg reflection corresponding to the particle size, and various colors can be produced by controlling the particle size. Therefore, a resin film formed from a resin composition containing the emulsion according to this embodiment also has structural coloring properties and is suitable as a material for articles exhibiting structural colors, and is suitable for improving the design of the articles.

[0080] 2. Method for Producing Emulsion Although the method for producing the emulsion according to this embodiment is not particularly limited, it is preferable to emulsion-polymerize monomer units containing the above-mentioned ethylene carbonate-containing acrylic monomer to thereby obtain an emulsion containing a (meth)acrylic acid ester copolymer as a dispersoid.

[0081] The emulsion polymerization may be carried out by a conventional method, for example, by stirring the ethylene carbonate-containing acrylic monomer, the other monomers as described above if desired, and an emulsifier in water as a dispersion medium, adding a polymerization initiator thereto, and stirring the mixture at a predetermined temperature, thereby allowing the emulsion polymerization to proceed.

[0082] The emulsifier is not particularly limited, but from the viewpoint of improving dispersion stability, anionic emulsifiers or nonionic emulsifiers are preferred, and anionic emulsifiers are more preferred.

[0083] Examples of anionic emulsifiers include sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkylphenyl ether sulfate, polyoxyethylene polycyclic phenyl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, and allyl alkyl sulfosuccinate. Examples of nonionic emulsifiers include polyoxyethylene alkyl ether and polyoxyethylene alkylphenyl ether. Among these, polyoxyethylene polycyclic phenyl ether sulfate is particularly preferred. These emulsifiers may be used alone or in combination of two or more.

[0084] From the viewpoint of the stability of the emulsion polymerization reaction and the prevention of deterioration of physical properties due to remaining unreacted emulsifier, the content of the emulsifier is preferably 1 part by mass or more, particularly preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, relative to 100 mass of the total amount of all monomers, and is preferably 30 parts by mass or less, particularly preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less, relative to 100 mass of the total amount of all monomers.

[0085] The polymerization initiator may be either water-soluble or oil-soluble. Examples include azo compounds such as 2,2'-azobis(2-methylpropionamidine) dihydrochloride and 2,2'-azobis(2-amidinopropane) dihydrochloride; persulfates such as potassium persulfate, sodium persulfate, and ammonium persulfate; and peroxides such as benzoyl peroxide, t-butyl hydroperoxide, and hydrogen peroxide. Redox initiators such as a combination of a persulfate and sodium bisulfite or a combination of a peracid and sodium ascorbate may also be used. The polymerization initiators may be used alone or in combination of two or more. Among these, ammonium persulfate is preferred from the viewpoint of excellent polymerization stability. These polymerization initiators may be used alone or in combination of two or more.

[0086] From the viewpoint of accelerating the polymerization rate, the content of the polymerization initiator is preferably 0.1 parts by mass or more, particularly preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, relative to 100 parts by mass of the total amount of all monomers. The content of the polymerization initiator is preferably 10 parts by mass or less, particularly preferably 7 parts by mass or less, and even more preferably 5 parts by mass or less, relative to 100 parts by mass of the total amount of all monomers.

[0087] The temperature and stirring conditions after addition of the polymerization initiator or monomer may be any conditions that allow sufficient dispersion of the dispersoids, but for example, the temperature is preferably 60 to 90°C, particularly preferably 65 to 85°C, and even more preferably 70 to 80°C. Furthermore, the stirring conditions are preferably 50 to 200 rpm, particularly preferably 70 to 180 rpm, and even more preferably 100 to 150 rpm. Furthermore, the stirring time is preferably 10 to 180 minutes, particularly preferably 10 to 60 minutes, and even more preferably 10 to 30 minutes.

[0088] Furthermore, it is preferable to further add aqueous ammonia, various water-soluble amines, or aqueous alkali solutions such as aqueous sodium hydroxide and aqueous potassium hydroxide to the emulsion obtained by emulsion polymerization to adjust the pH to 5 to 9, and particularly to 6 to 8.5, which makes it possible to improve the stability of the dispersion.

[0089] The solid content of the resulting emulsion is preferably 10 to 80% by mass, more preferably 25 to 70% by mass, and even more preferably 45 to 65% by mass.

[0090] 3. Method of Using the Emulsion The emulsion according to this embodiment can be used, for example, to produce a resin film. Details of the resin film will be described later.

[0091] [Article] Another embodiment of the present invention relates to an article comprising a resin film formed from a resin composition containing the above-described emulsion.

[0092] The resin film is not particularly limited as long as it is formed from a resin composition containing the emulsion according to this embodiment. More specific examples of the resin film include a pressure-sensitive adhesive layer, a self-supporting film, and a surface coating layer or an anchor coating layer formed on the surface of a predetermined substrate. In this specification, the term "self-supporting film" refers to a film that has enough strength to be handled independently without breakage and can maintain its shape even without a support.

[0093] The above-mentioned article depends on the type of resin film. For example, when the resin film is a pressure-sensitive adhesive layer, it becomes a pressure-sensitive adhesive sheet. When the resin film is a surface coating layer, the article may be a hard-coated film having a substrate film and a surface coating layer provided on the substrate. When the resin film is a self-supporting film, the article may be a pressure-sensitive adhesive sheet or hard-coated film having the self-supporting film, or may be a substrate film consisting only of the self-supporting film.

[0094] In the above-mentioned resin composition, the components other than the emulsion according to the present embodiment can be appropriately selected according to the type of resin film to be formed.For example, when forming a pressure-sensitive adhesive layer as a resin film, the resin composition preferably contains a pressure-sensitive adhesive component as a main material, and examples thereof include acrylic pressure-sensitive adhesive (acrylic polymer) etc.In addition, when forming a surface coating layer as a resin film, the resin composition preferably contains a curable component etc. as a main material.

[0095] In order to efficiently release carbon dioxide, the resin composition preferably contains a catalyst that promotes decomposition of the ethylene carbonate structure, and the nucleophilic anion generator is particularly preferred as the catalyst.

[0096] The nucleophilic anion generator is not particularly limited as long as it generates a nucleophilic anion upon heating and is capable of sufficiently releasing carbon dioxide gas from the ethylene carbonate structure contained in the pressure-sensitive adhesive composition according to the present embodiment using the nucleophilic anion. Examples of the nucleophilic anion include fluoride ions (F － ), chloride ions (Cl－ ), bromide ion (Br － ), iodide ion (I － ), hydroxide ions (OH － ) and the like, among which fluoride ions (F － ) and bromide ion (Br － ) is preferred, and fluoride ion (F － Examples of the cation constituting the nucleophilic anion generator include a quaternary ammonium cation, an imidazolium cation, a pyrrolidinium cation, a pyridinium cation, a piperidinium cation, a phosphonium cation, an alkali metal ion, and an alkaline earth metal ion, and among these, a quaternary ammonium cation is preferred.

[0097] Specific preferred examples of the nucleophilic anion generator include tetrabutylammonium fluoride (TBAF), tetrabutylammonium bromide (TBAB), 1-ethyl-3-methylimidazolium bromide, tetrabutylphosphonium bromide, sodium hydroxide, etc., and among these, tetrabutylammonium fluoride (TBAF) and tetrabutylammonium bromide (TBAB) are preferred. These nucleophilic anion generators may be used alone or in combination of two or more.

[0098] [Second Aspect] Hereinafter, an embodiment of the second aspect of the present invention will be described. [Fine Particles] The fine particles according to this embodiment contain, as a monomer unit constituting a polymer, a compound represented by the following formula (1): The (meth)acrylic acid ester polymer contains an ethylene carbonate-containing acrylic monomer having an ethylene carbonate structure represented by the formula:

[0099] The ethylene carbonate structure can release carbon dioxide by decomposition. In particular, when a nucleophilic anion is present together with the ethylene carbonate structure, the anion performs a nucleophilic attack on the carbon atom constituting the carbonyl group in the ethylene carbonate structure, thereby efficiently decomposing the ethylene carbonate structure and releasing carbon dioxide.

[0100] By using the microparticles according to the present embodiment having such properties, it is possible to manufacture products with excellent dismantling properties. That is, the carbon dioxide released from the microparticles can be used to reduce the adhesion between components constituting the product, thereby making it possible to easily dismantle the product. For example, when components are bonded together using a pressure-sensitive adhesive sheet manufactured using the microparticles as one of its materials, carbon dioxide can be generated by decomposition of the ethylene carbonate structure described above, and the carbon dioxide can be accumulated at the interface between the pressure-sensitive adhesive sheet and the components, allowing the pressure-sensitive adhesive sheet and the components to be physically separated.

[0101] The nucleophilic anions are preferably generated from a nucleophilic anion generator capable of generating nucleophilic anions in response to a predetermined stimulus. In particular, when a nucleophilic anion generator that generates the anions in response to heating is used, products using the microparticles according to the present embodiment can be disassembled by applying heat as an external stimulus.

[0102] 1. (Meth)acrylic Acid Ester Polymer The (meth)acrylic acid ester copolymer of the present embodiment is not particularly limited as long as it contains, as a monomer unit constituting the polymer, an ethylene carbonate-containing acrylic monomer having an ethylene carbonate structure represented by the above formula (1).

[0103] The ethylene carbonate-containing acrylic monomer is not particularly limited as long as it contains an ethylene carbonate structure and has a (meth)acryloyl group (structure). A preferred example of the ethylene carbonate-containing acrylic monomer is a (meth)acrylic acid ester having a structure in which an organic group having an ethylene carbonate structure and a (meth)acryloyloxy group are bonded. An example of such a (meth)acrylic acid ester is represented by the following formula (2): or an acrylic acid ester represented by the following formula (3): or a methacrylic acid ester represented by the following formula (4): In any of formulas (2) to (4), n and m are integers of 0 or more, and X represents hydrogen or a methyl group.

[0104] Among the (meth)acrylic acid esters represented by the above formulas (2) and (3), from the viewpoint of facilitating the release of carbon dioxide gas, (meth)acrylic acid esters in which n and m are each 1 or greater are preferred, and (meth)acrylic acid esters in which n and m are each 2 or greater are preferred. While the upper limit of each of the above n and m is not particularly limited, from the viewpoint of polymerizability, it is preferably 10 or less, more preferably 6 or less, particularly preferably 4 or less, and even more preferably 3 or less. Among these, (meth)acrylic acid esters in which n = 1 are preferred, and (2-oxo-1,3-dioxolan-4-yl)methyl methacrylate in which n = 1 in formula (3) is particularly preferred. The ethylene carbonate-containing monomers may be used singly or in combination of two or more.

[0105] As disclosed in JP-A-2006-335971, the ethylene carbonate-containing monomer is a compound that reacts with the epoxy group of a (meth)acrylate having an epoxy group by CO ion bonding. ２ That is, the (meth)acrylic acid ester copolymer according to the present embodiment, which uses an ethylene carbonate-containing monomer, can be produced using carbon dioxide as a production raw material, thereby enabling the effective use of carbon dioxide.

[0106] From the viewpoint of effectively using carbon dioxide as a production raw material, the (meth)acrylic acid ester copolymer in this embodiment preferably contains 50% by mass or more of the ethylene carbonate-containing acrylic monomer, particularly preferably 80% by mass or more, and even more preferably 85% by mass or more. Furthermore, the (meth)acrylic acid ester copolymer in this embodiment preferably contains 99.9% by mass or less of the ethylene carbonate-containing acrylic monomer, particularly preferably 99.5% by mass or less, and even more preferably 99.0% by mass or less. By ensuring a content of 99.9% by mass or less, the (meth)acrylic acid ester copolymer contains a sufficient amount of other constituent monomers, making it easier for the (meth)acrylic acid ester copolymer to have the desired performance.

[0107] The (meth)acrylic acid ester copolymer of this embodiment may contain, as a monomer unit constituting the polymer, a monomer other than the above-mentioned ethylene carbonate-containing acrylic monomer. Examples of such monomers include (meth)acrylic acid alkyl esters having an alkyl group containing 1 to 12 carbon atoms; monomers containing a reactive functional group such as a hydroxy group, a carboxy group, or an amino group; alkoxyalkyl group-containing (meth)acrylic acid esters; (meth)acrylic acid esters having an aromatic ring such as phenyl (meth)acrylate; non-crosslinkable acrylamides such as acrylamide and methacrylamide; (meth)acrylic acid esters having a non-crosslinkable tertiary amino group such as N,N-dimethylaminoethyl (meth)acrylate and N,N-dimethylaminopropyl (meth)acrylate; vinyl acetate; and styrene. These may be used alone or in combination of two or more.

[0108] Among the above, the (meth)acrylic acid ester copolymer in the present embodiment preferably contains, as a monomer unit constituting the polymer, acrylic acid, which corresponds to a monomer containing a carboxy group. When the (meth)acrylic acid ester copolymer contains acrylic acid, it becomes easy to adjust the average particle size of the obtained microparticles.

[0109] When the (meth)acrylic acid ester copolymer of this embodiment contains acrylic acid as a monomer unit constituting the polymer, the content thereof is preferably 0.1% by mass or more, particularly preferably 0.3% by mass or more, and even more preferably 0.5% by mass or more. Furthermore, the content is preferably 30% by mass or less, particularly preferably 20% by mass or less, and even more preferably 15% by mass or less. This makes it easy to adjust the average particle size of the resulting microparticles while ensuring a sufficient amount of the ethylene carbonate structure in the (meth)acrylic acid ester copolymer.

[0110] 2. Method for Producing Microparticles The method for producing the microparticles according to this embodiment is not particularly limited, but they can be produced by conventionally known polymerization methods such as suspension polymerization, emulsion polymerization, seed polymerization, and dispersion polymerization. Among these, it is preferable to obtain the microparticles according to this embodiment by emulsion polymerizing a monomer unit containing the ethylene carbonate-containing acrylic monomer described above to produce an emulsion containing the (meth)acrylic acid ester polymer as a dispersoid, and then removing the dispersion medium constituting the emulsion and pulverizing the resulting residue. Note that the microparticles according to this embodiment may be aggregated. Even if they are aggregated, they can be pulverized while maintaining the appearance of the particle surface.

[0111] The emulsion polymerization may be carried out by a conventional method, for example, by stirring the ethylene carbonate-containing acrylic monomer, the other monomers as described above if desired, and an emulsifier in water as a dispersion medium, adding a polymerization initiator thereto, and stirring the mixture at a predetermined temperature, thereby allowing the emulsion polymerization to proceed.

[0112] The emulsifier is not particularly limited, but from the viewpoint of improving dispersion stability, anionic emulsifiers or nonionic emulsifiers are preferred, and anionic emulsifiers are more preferred.

[0113] Examples of anionic emulsifiers include sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkylphenyl ether sulfate, polyoxyethylene polycyclic phenyl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, and allyl alkyl sulfosuccinate. Examples of nonionic emulsifiers include polyoxyethylene alkyl ether and polyoxyethylene alkylphenyl ether. Among these, polyoxyethylene polycyclic phenyl ether sulfate is particularly preferred. These emulsifiers may be used alone or in combination of two or more.

[0114] From the viewpoint of the stability of the emulsion polymerization reaction and the prevention of deterioration of physical properties due to remaining unreacted emulsifier, the content of the emulsifier is preferably 1 part by mass or more, particularly preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, relative to 100 mass of the total amount of all monomers, and is preferably 30 parts by mass or less, particularly preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less, relative to 100 mass of the total amount of all monomers.

[0115] The polymerization initiator may be either water-soluble or oil-soluble. Examples include azo compounds such as 2,2'-azobis(2-methylpropionamidine) dihydrochloride and 2,2'-azobis(2-amidinopropane) dihydrochloride; persulfates such as potassium persulfate, sodium persulfate, and ammonium persulfate; and peroxides such as benzoyl peroxide, t-butyl hydroperoxide, and hydrogen peroxide. Redox initiators such as a combination of a persulfate and sodium bisulfite or a combination of a peracid and sodium ascorbate may also be used. The polymerization initiators may be used alone or in combination of two or more. Among these, ammonium persulfate is preferred from the viewpoint of excellent polymerization stability. These polymerization initiators may be used alone or in combination of two or more.

[0116] From the viewpoint of accelerating the polymerization rate, the content of the polymerization initiator is preferably 0.1 parts by mass or more, particularly preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, relative to 100 parts by mass of the total amount of all monomers. The content of the polymerization initiator is preferably 10 parts by mass or less, particularly preferably 7 parts by mass or less, and even more preferably 5 parts by mass or less, relative to 100 parts by mass of the total amount of all monomers.

[0117] The temperature and stirring conditions after the addition of the polymerization initiator may be any conditions that allow the dispersoids to be sufficiently dispersed, but for example, the temperature is preferably 60 to 90°C, particularly preferably 65 to 85°C, and even more preferably 70 to 80°C. Furthermore, the stirring conditions are preferably 50 to 200 rpm, particularly preferably 70 to 180 rpm, and even more preferably 100 to 150 rpm. Furthermore, the stirring time is preferably 10 to 60 minutes, particularly preferably 10 to 60 minutes, and even more preferably 10 to 30 minutes.

[0118] Furthermore, it is preferable to further add aqueous ammonia, various water-soluble amines, or aqueous alkali solutions such as aqueous sodium hydroxide and aqueous potassium hydroxide to the emulsion obtained by emulsion polymerization to adjust the pH to 5 to 9, and particularly to 6 to 8.5, which makes it possible to improve the stability of the dispersion.

[0119] The solid content of the resulting emulsion is preferably 10 to 80% by mass, more preferably 25 to 70% by mass, and even more preferably 45 to 65% by mass.

[0120] Furthermore, in the obtained emulsion, the particle size (D50) of the dispersoid composed of the (meth)acrylic acid ester copolymer is preferably 10 nm or more, more preferably 30 nm or more, particularly preferably 50 nm or more, and even more preferably 100 nm or more. Furthermore, the particle size (D50) is preferably 1 μm or less, particularly preferably 0.8 μm or less, and even more preferably 0.6 μm or less. When the particle size (D50) of the dispersoid is within the above range, it becomes easy to adjust the average particle size of the microparticles according to this embodiment to the range described below. Note that details of the method for measuring the particle size (D50) are as described in the Examples below.

[0121] The method for removing the dispersion medium from the emulsion obtained as described above is not particularly limited, and examples include leaving the emulsion to stand in a predetermined temperature environment to dry the dispersion medium. In this case, the temperature is preferably 25°C or higher, particularly preferably 40°C or higher, and more preferably 45°C or higher. The temperature is preferably 100°C or lower, particularly preferably 90°C or lower, and more preferably 80°C or lower. Furthermore, the drying time is preferably 1 hour or longer, particularly preferably 2 hours or longer, and more preferably 3 hours or longer. The drying time is preferably 72 hours or shorter, particularly preferably 48 hours or shorter, and more preferably 24 hours or shorter. As a method for removing the dispersion medium from the emulsion obtained as described above, filtration or centrifugation may be performed. In addition, the fine particles may be washed with water or various organic solvents in order to remove the surfactant remaining on the surface of the fine particles.

[0122] As described above, removal of the dispersion medium from the emulsion leaves behind dispersoids as a residue. The method for pulverizing this residue is not particularly limited and can be appropriately selected depending on the state of aggregation. Examples include dry pulverization methods such as mortar pulverization, hammer mills, jet mills, and bead mills.

[0123] The average particle size of the microparticles obtained as described above is preferably 10 nm or more, particularly preferably 20 nm or more, and even more preferably 30 nm or more. Furthermore, the average particle size is preferably 1 μm or less, particularly preferably 0.9 μm or more, and even more preferably 0.8 μm or less. Having an average particle size within the above range makes the microparticles according to this embodiment more versatile. For example, when the microparticles according to this embodiment are added to a composition, the microparticles are easily mixed and dispersed. The average particle size of the microparticles is measured by observation using a scanning electron microscope, and details thereof are as described in the Examples below.

[0124] In addition, when the content of ethylene carbonate-containing acrylic monomer in the (meth)acrylic acid ester copolymer is 90 mass% or more and the average particle size of the particles is 100 nm or more, the particles according to this embodiment exhibit a structural color of any color resulting from Bragg reflection corresponding to the particle size, and various colors can be produced by controlling the particle size. Therefore, a resin film formed from a resin composition containing the particles according to this embodiment also has structural coloring properties and is suitable as a material for articles exhibiting structural colors, and is suitable for improving the design of the articles.

[0125] The applications of the microparticles according to this embodiment are not particularly limited, and they can be used, for example, as a foaming agent, antiblocking agent, slipping agent, light diffusing agent, etc. for resin films (coating layers, pressure-sensitive adhesive layers, resin films, etc.). Details of the resin films will be described later.

[0126] [Resin Composition and Article] Another embodiment of the present invention relates to a resin composition containing the above-described fine particles, and an article including a resin film formed from the resin composition.

[0127] In the resin composition, components other than the microparticles according to the present embodiment can be appropriately selected according to the type of resin film to be formed.For example, when forming a pressure-sensitive adhesive layer as the resin film, the resin composition preferably contains a pressure-sensitive adhesive component as the main material, and examples thereof include acrylic pressure-sensitive adhesives (acrylic polymers).In addition, when forming a coating layer (such as a surface coating layer or an anchor coating layer) as the resin film, the resin composition preferably contains a curable component as the main material.In addition, when forming a resin film as the resin film, the resin composition contains a thermoplastic resin as the main material, and the microparticles according to the present embodiment can be pre-dispersed in the thermoplastic resin and used as a masterbatch.

[0128] When the microparticles according to the present embodiment are used as a foaming agent, the resin composition preferably contains a catalyst that promotes decomposition of the ethylene carbonate structure, from the viewpoint of enabling efficient release of carbon dioxide. Examples of the catalyst include the nucleophilic anion generator.

[0129] The nucleophilic anion generator is not particularly limited as long as it generates a nucleophilic anion upon heating and is capable of sufficiently releasing carbon dioxide gas from the ethylene carbonate structure contained in the pressure-sensitive adhesive composition according to the present embodiment using the nucleophilic anion. Examples of the nucleophilic anion include fluoride ions (F － ), chloride ions (Cl － ), bromide ion (Br － ), iodide ion (I － ), hydroxide ions (OH － ) and the like, among which fluoride ions (F － ) and bromide ion (Br － ) is preferred, and fluoride ion (F －Examples of the cation constituting the nucleophilic anion generator include a quaternary ammonium cation, an imidazolium cation, a pyrrolidinium cation, a pyridinium cation, a piperidinium cation, a phosphonium cation, an alkali metal ion, and an alkaline earth metal ion, and among these, a quaternary ammonium cation is preferred.

[0130] Specific preferred examples of the nucleophilic anion generator include tetrabutylammonium fluoride (TBAF), tetrabutylammonium bromide (TBAB), 1-ethyl-3-methylimidazolium bromide, tetrabutylphosphonium bromide, sodium hydroxide, etc., and among these, tetrabutylammonium fluoride (TBAF) and tetrabutylammonium bromide (TBAB) are preferred. These nucleophilic anion generators may be used alone or in combination of two or more.

[0131] The resin film is not particularly limited as long as it is formed from a resin composition containing the fine particles according to the present embodiment. More specific examples of the resin film include a pressure-sensitive adhesive layer, a resin film, a surface coating layer formed on the surface of a predetermined substrate, or an anchor coating layer.

[0132] The above-mentioned article depends on the type of resin film. For example, when the resin film is a pressure-sensitive adhesive layer, it becomes a pressure-sensitive adhesive sheet. When the resin film is a surface coating layer, the article may be a hard-coated film having a substrate film and a surface coating layer provided on the substrate. When the resin film is a resin film, the article may be a pressure-sensitive adhesive sheet or hard-coated film having the resin film, or may be a substrate film consisting only of the resin film.

[0133] [Third Aspect] Hereinafter, an embodiment of the third aspect of the present invention will be described. [Resin Composition] The resin composition according to this embodiment contains, as a monomer unit constituting a polymer, a compound represented by the following formula (1): or fine particles containing the (meth)acrylic acid ester polymer as a dispersoid, the (meth)acrylic acid ester polymer containing an ethylene carbonate-containing acrylic monomer having an ethylene carbonate structure as shown in the formula (1), and a catalyst capable of nucleophilic attack on a carbon atom constituting a carbonyl group in the ethylene carbonate structure, thereby decomposing the ethylene carbonate structure and releasing carbon dioxide.

[0134] In the resin composition according to the present embodiment, the ethylene carbonate structure can be decomposed by the action of the catalyst to release carbon dioxide. By using a resin composition having such properties, it becomes possible to manufacture a product with excellent ease of disassembly. That is, the carbon dioxide released as described above can be used to reduce the adhesion between components constituting the product, thereby making it possible to easily disassemble the product. For example, when components are bonded together using a pressure-sensitive adhesive sheet manufactured using the resin composition according to the present embodiment, carbon dioxide can be generated by the decomposition of the ethylene carbonate structure described above. This carbon dioxide can be accumulated at the interface between the pressure-sensitive adhesive sheet and the component, allowing the pressure-sensitive adhesive sheet and the component to be physically separated.

[0135] The catalyst is preferably, for example, a nucleophilic anion generator capable of generating nucleophilic anions in response to a predetermined stimulus. The nucleophilic anions perform a nucleophilic attack on the carbon atoms constituting the carbonyl groups in the ethylene carbonate structure, thereby enabling efficient decomposition of the ethylene carbonate structure. When a nucleophilic anion generator that generates nucleophilic anions in response to heating is used, products that use the resin composition according to this embodiment can be disassembled by applying heat as an external stimulus.

[0136] 1. Emulsion / Fine Particles The emulsion in this embodiment is not particularly limited as long as it contains the above-described (meth)acrylic acid ester polymer as a dispersoid. Furthermore, the fine particles in this embodiment are not particularly limited as long as they contain the above-described (meth)acrylic acid ester polymer.

[0137] However, the emulsion in this embodiment is preferably an emulsion containing, as a dispersoid, a (meth)acrylic acid ester polymer obtained by emulsion polymerization of a monomer unit containing the above-mentioned ethylene carbonate-containing acrylic monomer. Furthermore, the fine particles in this embodiment are preferably fine particles obtained by removing the dispersion medium constituting the emulsion and pulverizing the residue obtained.

[0138] The (meth)acrylic acid ester copolymer is not particularly limited as long as it contains, as a monomer unit constituting the polymer, an ethylene carbonate-containing acrylic monomer having an ethylene carbonate structure represented by the above formula (1).

[0139] The ethylene carbonate-containing acrylic monomer is not particularly limited as long as it contains an ethylene carbonate structure and has a (meth)acryloyl group (structure). A preferred example of the ethylene carbonate-containing acrylic monomer is a (meth)acrylic acid ester having a structure in which an organic group having an ethylene carbonate structure and a (meth)acryloyloxy group are bonded. An example of such a (meth)acrylic acid ester is represented by the following formula (2): or an acrylic acid ester represented by the following formula (3): or a methacrylic acid ester represented by the following formula (4): In any of formulas (2) to (4), n and m represent integers of 0 or more, and X represents hydrogen or a methyl group.

[0140] Among the (meth)acrylic acid esters represented by the above formulas (2) to (4), from the viewpoint of easy and satisfactory release of carbon dioxide gas, (meth)acrylic acid esters in which n and m are each 1 or greater are preferred, and (meth)acrylic acid esters in which n and m are each 2 or greater are preferred. The upper limit values ​​of n and m are not particularly limited, but from the viewpoint of polymerizability, they are preferably 10 or less, more preferably 6 or less, particularly preferably 4 or less, and even more preferably 3 or less. Among these, (meth)acrylic acid esters in which n = 1 in the above formulas (2) and (3) are preferred, and (2-oxo-1,3-dioxolan-4-yl)methyl methacrylate in which n = 1 in the formula (3) is particularly preferred. The ethylene carbonate-containing monomers may be used singly or in combination of two or more.

[0141] As disclosed in JP-A-2006-335971, the ethylene carbonate-containing monomer is a compound that reacts with the epoxy group of a (meth)acrylate having an epoxy group by CO ion bonding. ２ That is, the (meth)acrylic acid ester copolymer according to the present embodiment, which uses an ethylene carbonate-containing monomer, can be produced using carbon dioxide as a production raw material, thereby enabling the effective use of carbon dioxide.

[0142] The (meth)acrylic acid ester copolymer of this embodiment preferably contains 1% by mass or more of the ethylene carbonate-containing acrylic monomer, particularly preferably 5% by mass or more, and even more preferably 10% by mass or more. This makes it easier for a resin film formed from the resin composition of this embodiment to generate carbon dioxide effectively. Furthermore, the (meth)acrylic acid ester copolymer of this embodiment preferably contains 99.9% by mass or less of the ethylene carbonate-containing acrylic monomer, particularly preferably 99.5% by mass or less, and even more preferably 99.0% by mass or less. This allows the (meth)acrylic acid ester copolymer to contain a sufficient amount of other constituent monomers, making it easier for the (meth)acrylic acid ester copolymer to have the desired performance.

[0143] The (meth)acrylic acid ester copolymer of this embodiment may contain, as a monomer unit constituting the polymer, a monomer other than the above-mentioned ethylene carbonate-containing acrylic monomer. Examples of such monomers include (meth)acrylic acid alkyl esters having an alkyl group containing 1 to 12 carbon atoms; monomers containing a reactive functional group such as a hydroxy group, a carboxy group, or an amino group; alkoxyalkyl group-containing (meth)acrylic acid esters; (meth)acrylic acid esters having an aromatic ring such as phenyl (meth)acrylate; non-crosslinkable acrylamides such as acrylamide and methacrylamide; (meth)acrylic acid esters having a non-crosslinkable tertiary amino group such as N,N-dimethylaminoethyl (meth)acrylate and N,N-dimethylaminopropyl (meth)acrylate; vinyl acetate; and styrene. These may be used alone or in combination of two or more.

[0144] Among the above, the (meth)acrylic acid ester copolymer in this embodiment preferably contains, as a monomer unit constituting the polymer, acrylic acid, which corresponds to a monomer containing a carboxy group. When the (meth)acrylic acid ester copolymer contains acrylic acid, it becomes easy to adjust the particle size (D50) of the resulting emulsion or the average particle size of the microparticles.

[0145] When the (meth)acrylic acid ester copolymer of this embodiment contains acrylic acid as a monomer unit constituting the polymer, the content thereof is preferably 0.1% by mass or more, particularly preferably 0.3% by mass or more, and even more preferably 0.5% by mass or more. Furthermore, the content is preferably 99% by mass or less, particularly preferably 98% by mass or less, and even more preferably 97% by mass or less. This makes it easy to adjust the particle size (D50) of the resulting emulsion or the average particle size of the microparticles while ensuring a sufficient amount of the ethylene carbonate structure in the (meth)acrylic acid ester copolymer.

[0146] As described above, the (meth)acrylic acid ester polymer in this embodiment is preferably obtained by emulsion polymerization of monomer units containing an ethylene carbonate-containing acrylic monomer. A conventionally known emulsion polymerization method can be used. For example, the ethylene carbonate-containing acrylic monomer, optionally the other monomers described above, and an emulsifier are stirred in water as a dispersion medium, and then a polymerization initiator is added thereto and the mixture is stirred at a predetermined temperature, thereby allowing emulsion polymerization to proceed.

[0147] The emulsifier is not particularly limited, but from the viewpoint of improving dispersion stability, anionic emulsifiers or nonionic emulsifiers are preferred, and anionic emulsifiers are more preferred.

[0148] Examples of anionic emulsifiers include sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkylphenyl ether sulfate, polyoxyethylene polycyclic phenyl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, and allyl alkyl sulfosuccinate. Examples of nonionic emulsifiers include polyoxyethylene alkyl ether and polyoxyethylene alkylphenyl ether. Among these, polyoxyethylene polycyclic phenyl ether sulfate is particularly preferred. These emulsifiers may be used alone or in combination of two or more.

[0149] From the viewpoint of the stability of the emulsion polymerization reaction and the prevention of deterioration of physical properties due to remaining unreacted emulsifier, the content of the emulsifier is preferably 1 part by mass or more, particularly preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, relative to 100 mass of the total amount of all monomers, and is preferably 30 parts by mass or less, particularly preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less, relative to 100 mass of the total amount of all monomers.

[0150] The polymerization initiator may be either water-soluble or oil-soluble. Examples include azo compounds such as 2,2'-azobis(2-methylpropionamidine) dihydrochloride and 2,2'-azobis(2-amidinopropane) dihydrochloride; persulfates such as potassium persulfate, sodium persulfate, and ammonium persulfate; and peroxides such as benzoyl peroxide, t-butyl hydroperoxide, and hydrogen peroxide. Redox initiators such as a combination of a persulfate and sodium bisulfite or a combination of a peracid and sodium ascorbate may also be used. The polymerization initiators may be used alone or in combination of two or more. Among these, ammonium persulfate is preferred from the viewpoint of excellent polymerization stability. These polymerization initiators may be used alone or in combination of two or more.

[0151] From the viewpoint of accelerating the polymerization rate, the content of the polymerization initiator is preferably 0.1 parts by mass or more, particularly preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, relative to 100 parts by mass of the total amount of all monomers. The content of the polymerization initiator is preferably 10 parts by mass or less, particularly preferably 7 parts by mass or less, and even more preferably 5 parts by mass or less, relative to 100 parts by mass of the total amount of all monomers.

[0152] The temperature and stirring conditions after the addition of the polymerization initiator may be any conditions that allow the dispersoids to be sufficiently dispersed, but for example, the temperature is preferably 60 to 90°C, particularly preferably 65 to 85°C, and even more preferably 70 to 80°C. Furthermore, the stirring conditions are preferably 50 to 200 rpm, particularly preferably 70 to 180 rpm, and even more preferably 100 to 150 rpm. Furthermore, the stirring time is preferably 10 to 180 minutes, particularly preferably 10 to 60 minutes, and even more preferably 10 to 30 minutes.

[0153] Furthermore, it is preferable to further add aqueous ammonia, various water-soluble amines, or aqueous alkali solutions such as aqueous sodium hydroxide and aqueous potassium hydroxide to the emulsion obtained by emulsion polymerization to adjust the pH to 5 to 9, and particularly to 6 to 8.5, which makes it possible to improve the stability of the dispersion.

[0154] The solid content of the resulting emulsion is preferably 10 to 80% by mass, more preferably 25 to 70% by mass, and even more preferably 45 to 65% by mass.

[0155] Furthermore, in the obtained emulsion, the particle size (D50) of the dispersoid composed of the (meth)acrylic acid ester copolymer is preferably 10 nm or more, more preferably 30 nm or more, particularly preferably 50 nm or more, and even more preferably 100 nm or more. Furthermore, the particle size (D50) is preferably 1 μm or less, particularly preferably 0.8 μm or less, and even more preferably 0.6 μm or less. By having the particle size (D50) of the dispersoid within the above range, the resin film formed from the resin composition according to this embodiment has a wider range of thickness options, is easily able to release sufficient carbon dioxide, and can be applied to a wide range of easily dismantled applications. Details of the method for measuring the particle size (D50) are as described in the Examples below.

[0156] The method for removing the dispersion medium from the emulsion obtained as described above is not particularly limited, and examples include leaving the emulsion to stand in a predetermined temperature environment to dry the dispersion medium. In this case, the temperature is preferably 25°C or higher, particularly preferably 40°C or higher, and more preferably 45°C or higher. The temperature is preferably 100°C or lower, particularly preferably 90°C or lower, and more preferably 80°C or lower. Furthermore, the drying time is preferably 1 hour or longer, particularly preferably 2 hours or longer, and more preferably 3 hours or longer. The drying time is preferably 72 hours or shorter, particularly preferably 48 hours or shorter, and more preferably 24 hours or shorter. Methods for removing the dispersion medium from the emulsion obtained as described above include filtration, centrifugation, etc. In addition, the fine particles may be washed with water or various organic solvents in order to remove the surfactant remaining on the surface of the fine particles.

[0157] As described above, removal of the dispersion medium from the emulsion leaves behind dispersoids as a residue. The method of pulverizing this residue to obtain fine particles is not particularly limited and can be appropriately selected depending on the state of aggregation, and examples thereof include dry pulverization methods such as mortar pulverization, hammer mills, jelly mills, and bead mills.

[0158] The average particle size of the microparticles obtained as described above is preferably 10 nm or more, more preferably 20 nm or more, particularly preferably 30 nm or more, and even more preferably 100 nm or more. When the average particle size is 10 nm or more, the resin film formed from the resin composition according to this embodiment is likely to release sufficient carbon dioxide. Furthermore, the average particle size is preferably 1 μm or less, particularly preferably 0.9 μm or more, and even more preferably 0.8 μm or less. When the average particle size is within the above range, the microparticles are easily mixed and dispersed well in the resin composition according to this embodiment. The average particle size of the microparticles is measured by observation using a scanning electron microscope, and details thereof are as described in the examples below.

[0159] 2. Catalyst The catalyst in the present embodiment is not particularly limited as long as it is capable of performing a nucleophilic attack on the carbon atom constituting the carbonyl group in the ethylene carbonate structure, thereby decomposing the ethylene carbonate structure and eliminating carbon dioxide. Preferred examples of the catalyst include nucleophilic anion generators capable of generating nucleophilic anions, and particularly preferred are nucleophilic anion generators capable of generating nucleophilic anions in response to a predetermined external stimulus.

[0160] Examples of the nucleophilic anion include fluoride ion (F － ), chloride ions (Cl － ), bromide ion (Br － ), iodide ion (I － ), hydroxide ions (OH － ) and the like, among which fluoride ions (F － ) and bromide ion (Br － ) is preferred, and fluoride ion (F －Examples of the cation constituting the nucleophilic anion generator include a quaternary ammonium cation, an imidazolium cation, a pyrrolidinium cation, a pyridinium cation, a piperidinium cation, a phosphonium cation, an alkali metal ion, and an alkaline earth metal ion, and among these, a quaternary ammonium cation is preferred.

[0161] Specific preferred examples of the nucleophilic anion generator include tetrabutylammonium fluoride (TBAF), tetrabutylammonium bromide (TBAB), 1-ethyl-3-methylimidazolium bromide, tetrabutylphosphonium bromide, sodium hydroxide, etc., and among these, tetrabutylammonium fluoride (TBAF) and tetrabutylammonium bromide (TBAB) are preferred. These nucleophilic anion generators may be used alone or in combination of two or more.

[0162] Examples of the external stimulus include heating and irradiation with active energy rays (laser irradiation, microwave irradiation, ultraviolet irradiation, etc.), and among these, heating is preferred. Heating is easy to treat and is preferable because it makes it easier to deliver the stimulus to the resin film formed from the resin composition according to the present embodiment even when it is deep inside the product, compared to other cases.

[0163] The content of the catalyst in the resin composition according to this embodiment is preferably 0.01 parts by mass or more, particularly preferably 0.1 parts by mass or more, and even more preferably 1 part by mass or more, relative to 100 parts by mass of the emulsion or fine particles. Furthermore, the content of the catalyst is preferably 10 parts by mass or less, particularly preferably 7 parts by mass or less, and even more preferably 5 parts by mass or less, relative to 100 parts by mass of the emulsion or fine particles. Having the catalyst content within the above range facilitates efficient carbon dioxide generation.

[0164] 3. Other Components The resin composition according to the present embodiment may contain components other than the emulsion, fine particles, and catalyst described above. In particular, such other components can be appropriately selected depending on the type of resin film formed from the resin composition according to the present embodiment.

[0165] For example, when a pressure-sensitive adhesive layer is formed as a resin film, the resin composition preferably contains a pressure-sensitive adhesive component as a main component, such as an acrylic pressure-sensitive adhesive (acrylic polymer), etc. Furthermore, when a surface coating layer is formed as a resin film, the resin composition preferably contains a curable component as a main component.

[0166] 4. Method for Preparing Resin Composition The method for preparing the resin composition according to this embodiment is not particularly limited, and the resin composition can be obtained, for example, by mixing the emulsion or fine particles described above, a catalyst, and, if desired, other components in a solvent.

[0167] [Resin Film / Article] Another embodiment of the present invention relates to a resin film formed from the resin composition described above and an article including the resin film.

[0168] The resin film according to this embodiment is not particularly limited as long as it is formed from the resin composition according to this embodiment. Specific examples of the resin film include a pressure-sensitive adhesive layer, an adhesive layer, a self-supporting film, and a surface coating layer or an anchor coating layer formed on the surface of a predetermined substrate. The term "self-supporting film" as used herein refers to a film that has enough strength to be handled independently without breakage and can maintain its shape, even without a support.

[0169] For example, when the resin film according to this embodiment is a pressure-sensitive adhesive layer, it may be in the form of a pressure-sensitive adhesive sheet having a resin film on at least one side of a substrate (film, paper, etc.), or a pressure-sensitive adhesive sheet having a release material on both sides of the resin film. When the resin film is a surface coating layer, it may be, for example, a coated film having a substrate (film, paper, etc.) and a surface coating layer provided on the substrate. When the resin film is a self-supporting film, the article may be a pressure-sensitive adhesive sheet or hard-coated film having the self-supporting film, or may be a substrate film consisting only of the self-supporting film.

[0170] Furthermore, the article according to this embodiment preferably includes the resin film and a component disposed on at least one surface of the resin film. The resin film releases carbon dioxide when heated as an external stimulus, allowing the component and the resin film to be disassembled. The material of the component is not particularly limited. Examples include polyolefins such as polyethylene, polypropylene, polybutene, and polystyrene; engineering plastics such as polycarbonate, polyester, polyamide, and polyacetal; metal, glass, and rubber. Applications of such an article are not particularly limited, and the article can be used in applications such as automobiles and rolling stock (bullet trains and trains), electrical appliances, building materials, woodworking, and bookbinding and packaging. Automotive-related applications include bonding interior materials such as ceilings, doors, and seats, and bonding and sealing exterior materials such as automotive lighting fixtures and side moldings. Specifically, the adhesive can be suitably used to bond and seal a plastic housing that holds a light source to a lens that protects the light source when manufacturing automotive lighting fixtures. Electrical applications include the assembly of lampshades, speakers, and the like. Further applications in the field of building materials and woodworking include adhesion of doors, access floors, multi-layer floors, furniture assembly, edge bonding, profile wrapping, etc. in construction sites and factory manufacturing of building materials.

[0171] Furthermore, another embodiment of the present invention relates to a separation method for separating components constituting the article according to the present embodiment from each other, and particularly to a separation method for separating the resin film and the component in the article.

[0172] The separation method preferably includes a step of heating the resin film to decompose the ethylene carbonate structure and generate carbon dioxide gas (gas generation step), and a step of separating the resin film from the member by the carbon dioxide gas accumulated at the interface between the resin film and the member (separation step).

[0173] The heating conditions in the gas generating step can be set appropriately depending on the form of the article, but for example, the temperature is preferably 150° C. to 250° C., particularly preferably 160° C. to 230° C., and further preferably 170° C. to 200° C. The heating time is preferably 1 minute to 30 minutes, particularly preferably 2 minutes to 15 minutes, and further preferably 3 minutes to 10 minutes.

[0174] The heating means is not particularly limited, and examples thereof include heating in an oven, heating with a heat gun, and heating on a hot plate.

[0175] After the heating, the article is preferably left to stand until a sufficient amount of carbon dioxide gas has accumulated at the interface between the resin film and the member. After a sufficient amount of carbon dioxide gas has accumulated, the subsequent separation step is carried out.

[0176] In the separation step, a process of separating the resin film from the member may be performed, or the resin film and the member may be separated by natural falling or natural collapse.

[0177] The above-described embodiments have been described to facilitate understanding of the present invention, and are not intended to limit the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention.

[0178] [First Aspect] The present invention will be described in more detail below with reference to examples of the first aspect, but the scope of the present invention is not limited to these examples.

[0179] Example 1-1 A solution containing 20 parts by mass of an ethylene carbonate-containing methacrylic monomer (a monomer produced using carbon dioxide as a raw material; 2-oxo-1,3-dioxolan-4-yl)methyl methacrylate) in which n is 1 in the above-mentioned formula (3), 0.2 parts by mass of acrylic acid, 1 part by mass of polyoxyethylene polycyclic phenyl ether sulfate (manufactured by Nippon Nyukazai Co., Ltd., product name "Newcol 707SF") as an emulsifier, and 130 parts by mass of purified water was stirred at 70°C and 170 rpm.

[0180] Subsequently, 0.3 parts by mass of ammonium persulfate (APS) was added to the solution as a polymerization initiator, and the mixture was then polymerized for 10 minutes by emulsion polymerization while stirring at 70°C and 160 rpm to prepare a (meth)acrylic acid ester polymer. This resulted in an emulsion in which the (meth)acrylic acid ester polymer was dispersed as a dispersoid in water as a dispersion medium.

[0181] In the obtained emulsion, the mass ratio of the ethylene carbonate-containing acrylic monomer constituting the (meth)acrylic acid ester polymer (A) to acrylic acid was about 99: 1, and the molar ratio was about 37: 1. The solids concentration of the emulsion was calculated to be 14.4 mass%.

[0182] Examples 1-2 to 1-5 Emulsions were prepared in the same manner as in Example 1, except that the composition of the (meth)acrylic acid ester polymer, the content of the ethylene carbonate-containing acrylic monomer in the (meth)acrylic acid ester polymer, the content of the emulsifier, and the content of purified water were changed as shown in Table 1. The solids concentrations of the obtained emulsions were calculated and found to be as shown in Table 1.

[0183] Example 1-6 A solution containing 5 parts by mass of 4-(oxiran-2-ylmethoxy)butyl acrylate, 0.32 parts by mass of lithium bromide, and 24 parts by mass of N-N'-dimethylformamide was purged with carbon dioxide gas, and then stirred at 60°C for 17 hours. After distilling off the N-N'-dimethylformamide under reduced pressure, ethyl acetate and purified water were added, followed by extraction and washing. Magnesium sulfate was added to the resulting organic layer, which was then dried. After filtration, the ethyl acetate was distilled off under reduced pressure, yielding a pale yellow liquid (yield 96%).

[0184] The component in the obtained pale yellow liquid was subjected to 1H NMR and 13C NMR measurements, and it was confirmed that it was an ethylene carbonate-containing acrylic monomer (4-((2-oxo-1,3-dioxolan-4-yl)methoxy)butyl acrylate) in which n is 1 and m is 4 in the above-mentioned formula (4).

[0185] A solution containing 15 parts by mass of the ethylene carbonate-containing methacrylic monomer (a monomer produced using carbon dioxide as a raw material) in which n is 1 in the above-mentioned formula (3), 5 parts by mass of the ethylene carbonate-containing acrylic monomer (a monomer produced using carbon dioxide as a raw material) in which n is 1 and m is 4 in the above-mentioned formula (4) prepared as described above, 0.8 parts by mass of acrylic acid, 1 part by mass of polyoxyethylene polycyclic phenyl ether sulfate (manufactured by Nippon Nyukazai Co., Ltd., product name "Newcol 707SF") as an emulsifier, and 130 parts by mass of purified water was stirred at 70°C and 170 rpm.

[0186] Subsequently, 0.3 parts by mass of ammonium persulfate (APS) was added to the solution as a polymerization initiator, and the mixture was then polymerized for 10 minutes by emulsion polymerization while stirring at 70°C and 160 rpm to prepare a (meth)acrylic acid ester polymer. This resulted in an emulsion in which the (meth)acrylic acid ester polymer was dispersed as a dispersoid in water as a dispersion medium.

[0187] In the obtained emulsion, the mass ratio of the ethylene carbonate-containing acrylic monomer constituting the (meth)acrylic acid ester polymer (A) to acrylic acid was approximately 96: 4, and the molar ratio was approximately 8.7: 1. The solids concentration of the emulsion was calculated to be 15.8 mass%.

[0188] Example 1-7 A solution containing 5 parts by mass of an ethylene carbonate-containing methacrylic monomer (a monomer produced using carbon dioxide as a raw material) in which n is 1 in the above-mentioned formula (3), 45 parts by mass of n-butyl acrylate, 50 parts by mass of 2-ethylhexyl acrylate, 0.5 parts by mass of acrylic acid, 1 part by mass of polyoxyethylene polycyclic phenyl ether sulfate (manufactured by Nippon Nyukazai Co., Ltd., product name "Newcol 707SF") as an emulsifier, and 150 parts by mass of purified water was stirred at 70°C and 130 rpm.

[0189] Subsequently, 0.3 parts by mass of ammonium persulfate (APS) as a polymerization initiator was added to the above solution, and then the mixture was polymerized for 120 minutes by emulsion polymerization while stirring at 70 ° C and 130 rpm to prepare a (meth)acrylic acid ester polymer. This resulted in an emulsion in which a (meth)acrylic acid ester polymer as a dispersoid was dispersed in water as a dispersion medium. The solid content concentrations of the obtained emulsions were calculated and were as shown in Table 1.

[0190] [Example 1-8] Emulsions were prepared in the same manner as in Example 1-76, except that the monomer composition of the (meth)acrylic acid ester polymer was changed as shown in Table 1. The solids concentration of each of the obtained emulsions was calculated and found to be as shown in Table 1.

[0191] Details of the abbreviations used in Table 1 (and Table 2 described later) are as follows: ECMA: (2-oxo-1,3-dioxolan-4-yl)methyl methacrylate ECMBA: 4-((2-oxo-1,3-dioxolan-4-yl)methoxy)butyl acrylate AAc: acrylic acid BA: n-butyl acrylate 2EHA: 2-ethylhexyl acrylate

[0192] Test Example 1-1 (Measurement of particle size (D50)) For the emulsions obtained in the examples, the particle size distribution of the dispersoid ((meth)acrylic acid ester polymer) in the emulsion was measured by dynamic light scattering using a dynamic light scattering particle size distribution measuring device (manufactured by Microtrac-Bell, product name "Nanotrac Wave") to determine the particle size (D50). The results are shown in Table 1.

[0193] [Test Example 1-2] (Evaluation of Stability) The emulsions obtained in the examples were stored at room temperature for 6 months, and then the average particle size (D50) was measured. The change from the average particle size (D50) immediately after production was confirmed, and the stability was evaluated based on the following criteria. The results are shown in Table 1. ◯: No change ×: Change

[0194] [Test Example 1-3] (Observation of structural color) The emulsion obtained in the example was dropped onto a glass substrate and dried at room temperature (20°C) and 50% RH. The obtained film was visually observed by several evaluators and evaluated for the color tone of the structural color. The evaluation results are shown in Table 1.

[0195] [Test Example 1-4] (CO ２ Calculation of the amount of carbon dioxide fixed) The amount (mass ratio) of carbon dioxide used (fixed) in the emulsion was calculated from the blend amount of ethylene carbonate-containing acrylic monomer in the emulsions obtained in Examples 1-1 to 1-7. ２ The amount of CO ２ The molecular weight (=44) of the ethylene carbonate-containing acrylic monomer (A) was divided by the molecular weight (=158) of the ethylene carbonate-containing acrylic monomer (B) or by the molecular weight (=244) of the ethylene carbonate-containing acrylic monomer (B), and the result was expressed as a percentage. The results are shown in Table 1.

[0196]

[0197] As shown in Table 1, it was confirmed that stable emulsion particles were obtained in Examples 1-1 to 1-7. It was also confirmed that the emulsions of Examples 1-1, 1-2, 1-4, and 1-5 exhibited structural coloring, and it was understood that a change in particle size resulted in a change in the hue of the observed structural color.

[0198] Example 2-1: 95 parts by mass of n-butyl acrylate and 5 parts by mass of acrylic acid were copolymerized by emulsion polymerization to obtain a (meth)acrylic acid ester copolymer as an adhesive component. 100 parts by mass of this (meth)acrylic acid ester copolymer (36% by mass in terms of solid content, the same applies hereinafter) was mixed with 10 parts by mass of the emulsion produced in Example 1-1 to obtain a coating liquid of an adhesive composition having a solid content concentration of 33% by mass.

[0199] The obtained coating liquid was applied to the release-treated surface of a release sheet using a coater. The coating layer was then heated at 100°C for 2 minutes to form a resin film. Next, the release-treated surface of another release sheet was attached to the resin film on the release sheet obtained above so that it was in contact with the resin film, thereby producing a pressure-sensitive adhesive sheet having a resin film (adhesive layer) with a thickness of 25 µm, i.e., a pressure-sensitive adhesive sheet having a configuration of release sheet / adhesive layer (thickness: 25 µm) / release sheet.

[0200] Examples 2-2 to 2-4 and Comparative Examples 2-1 to 2-3 Pressure-sensitive adhesive sheets were prepared in the same manner as in Example 2-1, except that the composition and content of the (meth)acrylic acid ester copolymer as the pressure-sensitive adhesive component, and the type and content of the emulsion used were changed as shown in Table 2.

[0201] [Test Example 2-1] (Measurement of gel fraction) The PSA sheets produced in Examples 2-1 to 2-4 and Comparative Examples 2-1 to 2-3 were cut to a size of 80 mm x 80 mm, the PSA layer was wrapped in a polyester mesh (mesh size 200), and the mass was weighed using a precision balance. The mass of the mesh alone was subtracted to calculate the mass of the PSA alone. This mass was designated M1.

[0202] Next, the adhesive wrapped in the polyester mesh was immersed in ethyl acetate at room temperature (23°C) for 72 hours. The adhesive was then removed and air-dried for 24 hours in an environment with a temperature of 23°C and a relative humidity of 50%, and then dried in an oven at 80°C for 12 hours. After drying, the mass was weighed using a precision balance, and the mass of the adhesive alone was calculated by subtracting the mass of the mesh alone. This mass was designated M2. The gel fraction (%) was expressed as (M2 / M1) x 100. The gel fraction of the adhesive was calculated from this. The results are shown in Table 2.

[0203] [Test Example 2-2] (Haze Value Measurement) The pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets produced in Examples 2-1 to 2-4 and Comparative Examples 2-1 to 2-3 were attached to glass to prepare measurement samples. After background measurement was performed in an empty state, the haze values ​​of the measurement samples were measured in accordance with JIS K7136:2000 using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "SH-7000"). The results are shown in Table 2.

[0204] [Test Example 2-3] (Measurement of total light transmittance) The pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets produced in Examples 2-1 to 2-4 and Comparative Examples 2-1 to 2-3 were attached to glass to prepare measurement samples. After background measurement was performed in an empty state, the total light transmittance of the measurement samples was measured in accordance with JIS K7361-1:1997 using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "SH-7000"). The results are shown in the table.

[0205] [Test Example 2-4] (Measurement of chromaticity b*) The chromaticity b* defined by the CIE1976 L*a*b* color system was measured for the adhesive layer side of the pressure-sensitive adhesive sheets produced in Examples 2-1 to 2-4 and Comparative Examples 2-1 to 2-3 using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "SH-7000"). The results are shown in Table 2.

[0206] [Test Example 2-5] (Measurement of adhesive strength) One release sheet was peeled off from each of the pressure-sensitive adhesive sheets produced in Examples 2-1 to 2-4 and Comparative Examples 2-1 to 2-3, and the exposed pressure-sensitive adhesive layer was attached to an easy-adhesion layer of a polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., product name "Cosmoshine A4360", thickness: 50 μm) having an easy-adhesion layer, to obtain a release sheet / adhesive layer / PET film laminate. The obtained laminate was cut into a width of 25 mm and a length of 100 mm.

[0207] Next, the release sheet was peeled from the laminate under an environment of 23°C and 50% RH, and the exposed adhesive layer was attached to a soda-lime glass plate (manufactured by Nippon Sheet Glass Co., Ltd., product name "Soda Lime Glass", thickness: 1.1 mm). After leaving it under conditions of 23°C and 50% RH for 24 hours, the adhesive strength was measured when the laminate of the PET film and the adhesive layer was peeled from the adherend using a tensile tester (manufactured by Orientec Co., Ltd., Tensilon) at a peel speed of 300 mm / min and a peel angle of 180°. Measurements were conducted under conditions other than those described here in accordance with JIS Z0237:2009. The results are shown in Table 2.

[0208] Test Example 2-6 (Measurement of Storage Modulus) The pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets produced in Examples 2-1 to 2-4 and Comparative Examples 2-1 to 2-3 were laminated together to form a laminate with a thickness of 0.8 mm. From the resulting pressure-sensitive adhesive layer laminate, a cylindrical object with a diameter of 8 mm (height of 0.8 mm) was punched out and used as a sample. The storage modulus G' and loss tangent (tan δ) of the sample were measured at -20°C, 25°C, and 100°C by the torsional shear method using a viscoelasticity measuring device (manufactured by Anton Paar, product name "MCR302") in accordance with JIS K7244-6 under the following conditions. The results are shown in Table 2. Measurement frequency: 1 Hz Measurement temperatures: -20°C, 25°C, 100°C

[0209] [Test Example 2-7] (CO ２ Calculation of the amount of carbon dioxide fixed) The amount (mass ratio) of carbon dioxide used (fixed) in the PSA sheets was calculated from the blend amount of ethylene carbonate-containing acrylic monomer in the PSA sheets produced in the Examples and Comparative Examples. ２ The amount of CO２ The molecular weight of the ethylene carbonate-containing acrylic monomer (A) (= 158) was divided by the molecular weight of the ethylene carbonate-containing acrylic monomer (A) (= 44) and expressed as a percentage. The results are shown in Table 2.

[0210]

[0211] As shown in Table 2, the PSA sheets produced in Examples 2-1 to 2-4 immobilized a predetermined amount of carbon dioxide and had physical properties that made them suitable for a variety of uses.

[0212] [Preparation Example 1] 95 parts by mass of n-butyl acrylate and 5 parts by mass of acrylic acid were copolymerized by emulsion polymerization to obtain a (meth)acrylic acid ester copolymer as the main material of the adhesive component. 100 parts by mass of this main material (36% by mass in terms of solid content, the same applies below) was mixed with 10 parts by mass of the emulsion produced in Example 1-1 and 2 parts by mass of tetrabutylammonium bromide (TBAB) as a catalyst to obtain a coating solution of an adhesive composition with a solid content concentration of 33% by mass.

[0213] The obtained coating liquid was applied using a coater to the release-treated surface of a release sheet (a release sheet in which one side of a polyethylene terephthalate film was release-treated with a silicone-based release agent, manufactured by Lintec Corporation, product name "SP-PET752150"). The coating layer was then heat-treated at 100°C for 2 minutes to form a resin film. Next, the release-treated surface of another release sheet (a release sheet in which one side of a polyethylene terephthalate film was release-treated with a silicone-based release agent, manufactured by Lintec Corporation, product name "SP-PET381031") was attached so as to contact the resin film on the release sheet obtained above, thereby producing a pressure-sensitive adhesive sheet having a resin film (adhesive layer) with a thickness of 25 μm, i.e., a pressure-sensitive adhesive sheet having a configuration of release sheet / adhesive layer (thickness: 25 μm) / release sheet.

[0214] [Preparation Example 2] A pressure-sensitive adhesive sheet was obtained in the same manner as in Preparation Example 1, except that the content of the emulsion was 20 parts by mass and the content of the catalyst (TBAB) was 4 parts by mass.

[0215] [Preparation Example 3] A pressure-sensitive adhesive sheet was obtained in the same manner as in Preparation Example 1, except that the content of the emulsion was 20 parts by mass and 4 parts by mass of tetrabutylammonium fluoride (TBAF) was used as the catalyst.

[0216] Preparation Example 4: 100 parts by mass of the emulsion produced in Example 1-1 and 10 parts by mass of tetrabutylammonium fluoride (TBAF) as a catalyst were mixed to obtain a coating solution of a resin composition with a solids concentration of 33% by mass. The obtained coating solution was applied to the release-treated surface of a release sheet (a polyethylene terephthalate film with one side treated with a silicone-based release agent, manufactured by Lintec Corporation, product name "SP-PET752150") using a coater. The coating layer was then heat-treated at 100°C for 2 minutes to form a resin film (thickness: 25 μm).

[0217] Preparation Example 5 A resin film was obtained in the same manner as in Preparation Example 4, except that 30 parts by mass of tetrabutylammonium bromide (TBAB) was used as the catalyst.

[0218] [Test Example 3-1] (Measurement of 5% weight loss temperature) The 5% weight loss temperature of the pressure-sensitive adhesive sheets or resin films produced in Preparation Examples 1 to 5 was measured using a differential thermal and thermogravimetric simultaneous analyzer (manufactured by Shimadzu Corporation, product name "DTG-60") in accordance with JIS K7120: 1987. The results are shown in Table 3.

[0219] Test Example 3-2 (Evaluation of Foamability) The coating solutions of the resin compositions of Preparation Examples 1 to 5 were applied to the aluminum foil surface of a composite substrate (PET50A4360 Alpet manufactured by Toyobo Co., Ltd., thickness: 40 μm) made by bonding aluminum foil and a polyethylene terephthalate film using a coater. The coating layer was then heated at 100°C for 2 minutes to form a resin film (thickness: 25 μm). The exposed surface of the resin film was then attached to a glass plate, which served as a bubble confirmation sample. These bubble confirmation samples were heated by placing them in a thermostatic oven at 180°C for 1 minute, and the presence or absence of bubbles at the interface between the pressure-sensitive adhesive layer and the glass plate was confirmed before and after heating. The foamability was then evaluated based on the following criteria. The results are shown in Table 2. ⊚: Bubbles were observed throughout the interface. ◯: Bubbles were observed partially at the interface. ×: Almost no bubbles were observed at the interface.

[0220]

[0221] As shown in Table 3, the pressure-sensitive adhesive sheets or resin films according to Preparation Examples 1 to 5 were found to be excellent in the evaluation of foaming properties (that is, they generated a large amount of bubbles).

[0222] The above results are presumably due to the fact that, in the pressure-sensitive adhesive layers or resin films according to Preparation Examples 1 to 5, the ethylene carbonate structure in the (meth)acrylic acid ester polymer carried out nucleophilic attack on the carbon atom constituting the carbonyl group in the ethylene carbonate structure in the presence of a nucleophilic anion, thereby efficiently decomposing the ethylene carbonate structure due to heat. That is, in Preparation Examples 1 to 5, decomposition of the ethylene carbonate structure caused carbon dioxide to be released from the pressure-sensitive adhesive layer, which is presumably responsible for the accelerated weight loss and the generation of many bubbles.

[0223] [Second Aspect] The second aspect of the present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited to these examples.

[0224] Example 1 A solution containing 20 parts by mass of an ethylene carbonate-containing acrylic monomer (a monomer produced using carbon dioxide as a raw material; 2-oxo-1,3-dioxolan-4-yl)methyl methacrylate) in which n is 2 in the above-mentioned formula (3), 0.2 parts by mass of acrylic acid, 1 part by mass of polyoxyethylene polycyclic phenyl ether sulfate (manufactured by Nippon Nyukazai Co., Ltd., product name "Newcol 707SF") as an emulsifier, and 65 parts by mass of purified water was stirred at 70°C and 170 rpm.

[0225] Subsequently, 0.3 parts by mass of ammonium persulfate (APS) was added to the solution as a polymerization initiator, and the mixture was then polymerized for 10 minutes by emulsion polymerization while stirring at 70°C and 160 rpm to prepare a (meth)acrylic acid ester polymer. This resulted in an emulsion in which the (meth)acrylic acid ester polymer was dispersed as a dispersoid in water as a dispersion medium.

[0226] In the obtained emulsion, the mass ratio of the ethylene carbonate-containing acrylic monomer constituting the (meth)acrylic acid ester polymer (A) to acrylic acid was approximately 99:1, and the molar ratio was approximately 37:1. The solids concentration of the emulsion was calculated to be 14.4% by mass. Furthermore, when the particle size distribution of the dispersoid ((meth)acrylic acid ester polymer) in the emulsion was measured by DLS, the particle size (D50) was 260 nm.

[0227] The emulsion obtained as described above was left to stand overnight in an environment of 50°C to dry the dispersion medium. The residue remaining after drying was crushed in a mortar to obtain fine particles. The fine particles were vapor-deposited with osmium and then observed with a scanning electron microscope (SEM). The observation results are shown in Figure 1. The obtained image was subjected to circle detection and binarization processing using image analysis software, and the circle-equivalent diameter of each particle was measured to create a histogram of the particle size distribution of the fine particles. The average particle size was calculated from the histogram and was found to be 236 nm.

[0228] Examples 2 to 5 Emulsions were prepared in the same manner as in Example 1, except that the composition of the (meth)acrylic acid ester polymer, the content of the ethylene carbonate-containing acrylic monomer in the (meth)acrylic acid ester polymer, the content of the emulsifier, and the content of purified water were changed as shown in Table 4. The solids concentration and particle size (D50) of each of the obtained emulsions were calculated, and the results were as shown in Table 4. The average particle size of the obtained microparticles was measured in the same manner as in Example 1, and the average particle size was as shown in Table 4.

[0229] Example 6 A solution containing 5 parts by mass of 4-(oxiran-2-ylmethoxy)butyl acrylate, 0.32 parts by mass of lithium bromide, and 24 parts by mass of N-N'-dimethylformamide was purged with carbon dioxide gas, and then stirred at 60°C for 17 hours. After distilling off the N-N'-dimethylformamide under reduced pressure, ethyl acetate and purified water were added, followed by extraction and washing. Magnesium sulfate was added to the resulting organic layer, which was then dried. After filtration, the ethyl acetate was distilled off under reduced pressure, yielding a pale yellow liquid (yield 96%).

[0230] The component in the obtained pale yellow liquid was subjected to 1H NMR and 13C NMR measurements, and it was confirmed that it was an ethylene carbonate-containing acrylic monomer (4-((2-oxo-1,3-dioxolan-4-yl)methoxy)butyl acrylate) in which n is 1 and m is 4 in the above-mentioned formula (4).

[0231] A solution containing 15 parts by mass of the ethylene carbonate-containing methacrylic monomer (a monomer produced using carbon dioxide as a raw material) in which n is 1 in the above-mentioned formula (3), 5 parts by mass of the ethylene carbonate-containing acrylic monomer (a monomer produced using carbon dioxide as a raw material) in which n is 1 and m is 4 in the above-mentioned formula (4) prepared as described above, 0.8 parts by mass of acrylic acid, 1 part by mass of polyoxyethylene polycyclic phenyl ether sulfate (manufactured by Nippon Nyukazai Co., Ltd., product name "Newcol 707SF") as an emulsifier, and 130 parts by mass of purified water was stirred at 70°C and 170 rpm.

[0232] Subsequently, 0.3 parts by mass of ammonium persulfate (APS) was added to the solution as a polymerization initiator, and the mixture was then polymerized for 10 minutes by emulsion polymerization while stirring at 70°C and 160 rpm to prepare a (meth)acrylic acid ester polymer. This resulted in an emulsion in which the (meth)acrylic acid ester polymer was dispersed as a dispersoid in water as a dispersion medium.

[0233] In the obtained emulsion, the mass ratio of the ethylene carbonate-containing acrylic monomer constituting the (meth)acrylic acid ester polymer (A) to acrylic acid was approximately 96: 4, and the molar ratio was approximately 8.7: 1. The solids concentration of the emulsion was calculated to be 15.8 mass%.

[0234] Details of the abbreviations in Table 4 are as follows: ECMA: (2-oxo-1,3-dioxolan-4-yl)methyl methacrylate ECMBA: 4-((2-oxo-1,3-dioxolan-4-yl)methoxy)butyl acrylate AAc: acrylic acid MMA: methyl methacrylate

[0235] Comparative Example 1 An emulsion was prepared in the same manner as in Example 1, except that only methyl methacrylate monomer was used and the emulsifier content and purified water content were changed as shown in Table 4. The solids concentration of the obtained emulsion was calculated, and the result was as shown in Table 4. The particle size distribution of the dispersoid in the obtained emulsion was measured in the same manner as in Example 1, and the particle size (D50) was as shown in Table 4.

[0236] Furthermore, from the emulsion obtained as described above, microparticles were obtained in the same manner as in Example 1. When the microparticles were observed with a scanning electron microscope in the same manner as in Example 1, the average particle size was found to be as shown in Table 4.

[0237] [Test Example 1] (CO ２ Calculation of the amount of carbon dioxide fixed) The amount (mass ratio) of carbon dioxide used (fixed) in the emulsion was calculated from the blend amount of ethylene carbonate-containing acrylic monomer in the microparticles obtained in the Examples and Comparative Examples. ２The amount of CO ２ The molecular weight of the ethylene carbonate-containing acrylic monomer (A) (= 158) was divided by the molecular weight of the ethylene carbonate-containing acrylic monomer (A) (= 44) and expressed as a percentage. The results are shown in Table 4.

[0238] [Test Example 2] (Observation of structural color) The fine particles obtained in the examples and comparative examples were visually observed by several evaluators and evaluated for the color tone of the structural color. The evaluation results are shown in Table 4.

[0239]

[0240] As shown in Table 4, it was confirmed that fine particles with particle sizes of 66 nm to 361 nm were obtained in the examples. It was also confirmed that the fine particles of Examples 1-2 and 4-5 exhibited structural coloring, and it was understood that a change in particle size resulted in a change in the hue of the observed structural color. Furthermore, the ethylene carbonate-containing acrylic monomer is a monomer produced using carbon dioxide as a raw material, and therefore has a low environmental impact.

[0241] [Third Aspect] Hereinafter, the third aspect of the present invention will be described in more detail with reference to examples, but the scope of the present invention is not limited to these examples.

[0242] [Preparation of emulsion and microparticles] [Preparation Example 1] A solution containing 20 parts by mass of an ethylene carbonate-containing acrylic monomer (a monomer produced using carbon dioxide as a raw material) in which n is 2 in the above-mentioned formula (3), 0.2 parts by mass of acrylic acid, 1 part by mass of polyoxyethylene polycyclic phenyl ether sulfate (manufactured by Nippon Nyukazai Co., Ltd., product name "Newcol 707SF") as an emulsifier, and 130 parts by mass of purified water was stirred at 70°C and 170 rpm.

[0243] Subsequently, 0.3 parts by mass of ammonium persulfate (APS) was added to the solution as a polymerization initiator, and the mixture was then polymerized for 10 minutes by emulsion polymerization while stirring at 70°C and 160 rpm to prepare a (meth)acrylic acid ester polymer. This resulted in an emulsion in which the (meth)acrylic acid ester polymer was dispersed as a dispersoid in water as a dispersion medium.

[0244] In the obtained emulsion, the mass ratio of the ethylene carbonate-containing acrylic monomer constituting the (meth)acrylic acid ester polymer (A) to acrylic acid was approximately 99:1, and the molar ratio was approximately 37:1. The solids concentration of the emulsion was calculated to be 14.4% by mass. Furthermore, when the particle size distribution of the dispersoid ((meth)acrylic acid ester polymer) in the emulsion was measured by DLS, the particle size (D50) was 142 nm.

[0245] The emulsion obtained as described above was left to stand overnight in an environment of 50°C to dry the dispersion medium. The residue remaining after drying was crushed in a mortar to obtain fine particles. The fine particles were vapor-deposited with osmium and then observed with a scanning electron microscope (SEM). Circle detection and binarization of the obtained image revealed an average particle size of 132 nm.

[0246] Furthermore, the amount (mass ratio) of carbon dioxide used (fixed) in the emulsion was calculated from the blending amount of the ethylene carbonate-containing acrylic monomer in the obtained emulsion. ２ The amount of immobilization was calculated to be 27.6%. ２ The molecular weight (=44) of the ethylene carbonate-containing acrylic monomer (A) was divided by the molecular weight (=158) of the ethylene carbonate-containing acrylic monomer (A) and expressed as a percentage.

[0247] [Resin Composition] [Example 1-1] 100 parts by mass (solid content equivalent, the same applies hereinafter) of the emulsion produced in Preparation Example 1 and 5 parts by mass of tetrabutylammonium bromide (TBAB) as a catalyst were mixed and left to stand overnight in an environment of 50°C to dry the dispersion medium. A residue (resin composition) remaining after drying was obtained.

[0248] Examples 1-2 to 1-8 Resin compositions were obtained in the same manner as in Example 1-1, except that the type and content of the catalyst were changed as shown in Table 5. In Table 6, "TBAB" means the above-mentioned tetrabutylammonium bromide, and "TBAF" means tetrabutylammonium fluoride.

[0249] Comparative Example 1-1 A resin composition was obtained in the same manner as in Example 1-1, except that no catalyst was used.

[0250] Test Example 1-1 (Measurement of 5% weight loss temperature) The 5% weight loss temperatures of the resin compositions prepared in Examples 1-1 to 1-8 were measured using a differential thermal and thermogravimetric simultaneous analyzer (manufactured by Shimadzu Corporation, product name "DTG-60") in accordance with JIS K7120: 1987. The results are shown in Table 5.

[0251]

[0252] As can be seen from each of Examples 1-1 to 1-4 and Examples 1-5 to 1-8 in Table 5, the 5% weight loss temperature generally decreased as the amount of catalyst increased. This is presumably because the larger the amount of catalyst, the more efficiently the decomposition of the ethylene carbonate structure derived from the ethylene carbonate-containing acrylic monomer proceeded, resulting in more efficient release of carbon dioxide.

[0253] Furthermore, a comparison of Examples 1-1 to 1-4 with Examples 1-5 to 1-8 revealed that the 5% weight loss temperature was lower when tetrabutylammonium fluoride (TBAF) was used as a catalyst than when tetrabutylammonium bromide (TBAB) was used, i.e., the decomposition of the ethylene carbonate structure proceeded more efficiently.

[0254] [Adhesive Sheet] [Example 2-1] 95 parts by mass of n-butyl acrylate and 5 parts by mass of acrylic acid were copolymerized by emulsion polymerization to obtain a (meth)acrylic acid ester copolymer as the main adhesive component. 100 parts by mass of this main material (36% by mass in terms of solids content, the same applies below) was mixed with 10 parts by mass of the emulsion produced in Preparation Example 1 and 2 parts by mass of tetrabutylammonium bromide (TBAB) as a catalyst to obtain a coating solution of a resin composition (adhesive composition) with a solids concentration of 33% by mass.

[0255] The obtained coating solution was applied using a coater to the release-treated surface of a heavy-release release sheet (manufactured by Lintec Corporation, product name "SP-PET752150"), where one side of a polyethylene terephthalate film had been release-treated with a silicone-based release agent. The coating layer was then heat-treated at 100°C for 2 minutes to form a coating layer. Next, the coating layer on the heavy-release release sheet obtained above and a light-release release sheet (manufactured by Lintec Corporation, product name "SP-PET381031"), where one side of a polyethylene terephthalate film had been release-treated with a silicone-based release agent, were laminated together so that the release-treated surface of the light-release release sheet was in contact with the coating layer, to produce a pressure-sensitive adhesive sheet having a thickness of 25 μm, i.e., PSA Sheet 1 having a configuration of heavy-release release sheet / adhesive layer (thickness: 25 μm) / light-release release sheet. In addition, adhesive sheet 2 was produced by bonding the coating layer on the heavy release type release sheet obtained above to a composite substrate (Alpet thickness: 40 μm) made by bonding aluminum foil and polyethylene terephthalate film together so that the release-treated surface of the light release type release sheet was in contact with the coating layer.

[0256] [Examples 2-2 and 2-3] PSA sheets were obtained in the same manner as in Example 2-1, except that the content of the emulsion produced in Preparation Example 1 and the type and content of the catalyst were changed as shown in Table 6. In Table 6, "TBAB" means the above-mentioned tetrabutylammonium bromide, and "TBAF" means tetrabutylammonium fluoride.

[0257] Comparative Example 2-1 A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 2-1, except that no catalyst was used.

[0258] [Test Example 2-1] (Measurement of 5% weight loss temperature) The 5% weight loss temperature of the adhesives constituting the adhesive layers prepared in Examples 2-1 to 2-3 and Comparative Example 2-1 was measured using a differential thermal and thermogravimetric simultaneous analyzer (manufactured by Shimadzu Corporation, product name "DTG-60") in accordance with JIS K7120: 1987. The results are shown in Table 6.

[0259] Test Example 2-2 (Evaluation of Foaming Properties) The release sheets were peeled from the pressure-sensitive adhesive sheets produced in Examples 2-1 to 2-3 and Comparative Example 2-1, and the exposed surface of the pressure-sensitive adhesive layer was attached to a glass plate to prepare a bubble-checking sample. The bubble-checking sample was heated by placing it in a thermostatic oven at 180°C for 1 minute, and the presence or absence of bubbles at the interface between the pressure-sensitive adhesive layer and the glass plate was confirmed before and after heating. The foaming properties were then evaluated based on the following criteria. The results are shown in Table 6. ⊚: Bubbles were observed throughout the interface. ◯: Bubbles were observed partially at the interface. ×: Almost no bubbles were observed at the interface.

[0260] Test Example 2-3 (Evaluation of Ease of Dismantling) The release sheets were peeled from the pressure-sensitive adhesive sheets produced in Examples 2-1 to 2-3 and Comparative Example 2-1, and the exposed surface of the pressure-sensitive adhesive layer was attached to a glass plate to prepare a sample for confirming dismantling. The sample for confirming dismantling was placed on a hot plate at 200°C and heated for 2 minutes. During heating, an attempt was made to manually peel the interface between the pressure-sensitive adhesive layer and the glass plate. Dismantling was then evaluated based on the following criteria. The results are shown in Table 6. ⊚: Easily removable by manual peeling. ◯: Relatively easily removable by manual peeling. ×: Difficult to remove by manual peeling.

[0261] FIG. 1 shows the state of foaming after heating (FIG. 1a) and the state of peeling (FIG. 1b) for the dismantling confirmation sample according to Example 2-2.

[0262]

[0263] As shown in Table 6, the PSA sheets according to Examples 2-1 to 2-3 had a lower 5% weight loss temperature of the PSA layer than the Reference Example, and the lower the 5% weight loss temperature, the better the evaluation result of foamability (i.e., the more bubbles were generated).

[0264] The above results are presumed to be due to thermal decomposition of the ethylene carbonate structure in the (meth)acrylic acid ester polymer in the PSA layers of Examples 2-1 to 2-3. That is, in Examples 2-1 to 2-3, decomposition of the ethylene carbonate structure causes carbon dioxide to be released from the PSA layer, which is presumed to have accelerated the weight loss and generated many bubbles.

[0265] The emulsion of the present invention according to the first aspect can fix carbon dioxide and is useful for environmental protection. Furthermore, the emulsion of the present invention is useful in a wide range of fields, including paints, adhesives, pressure-sensitive adhesives, paper processing, dyes, fiber processing, printing inks, cement admixtures, coating agents, and films. Furthermore, since the emulsion of the present invention has structural coloring properties, it is suitable as a material for structural color-exhibiting products. Furthermore, since the emulsion of the present invention decomposes upon heat treatment with a catalyst and releases carbon dioxide, it can be suitably used in the production of products that require easy disassembly.

[0266] The microparticles of the second aspect of the invention can immobilize carbon dioxide and are useful for environmental protection. Furthermore, the microparticles of the present invention are useful in a wide range of applications, including as additives for resin films, paints, adhesives, and pressure-sensitive adhesives, such as antiblocking agents, toner additives, powder coatings, water-dispersible coatings, decorative laminate additives, artificial marble additives, cosmetic fillers, chromatography column fillers, and matting agents. Furthermore, the microparticles of the present invention have structural coloring properties, making them suitable as materials for structural color-exhibiting products. Furthermore, the microparticles of the present invention decompose upon heat treatment with a catalyst, releasing carbon dioxide, making them suitable for use in the manufacture of products that require easy disassembly.

[0267] The resin composition of the present invention according to the third aspect can be suitably used for the production of products that require easy dismantling, specifically in a wide range of fields such as paints, adhesives, pressure-sensitive adhesives, paper processing, dyes, fiber processing, printing inks, cement admixtures, coating agents, and films.

Claims

1. As a monomer unit constituting a polymer, 2. An emulsion comprising, as a dispersoid, a (meth)acrylic acid ester polymer containing an ethylene carbonate-containing acrylic monomer having an ethylene carbonate structure represented by the formula:

2. The emulsion described in claim 1, characterized in that the (meth)acrylic acid ester polymer contains the ethylene carbonate-containing monomer in an amount of 1% by mass or more and 99.9% by mass or less as a monomer unit constituting the polymer.

3. The emulsion according to claim 1, wherein the ethylene carbonate-containing acrylic monomer is a compound represented by any one of the following formulas (2) to (4): (In the formula, n represents an integer of 0 or more.) (In the formula, n represents an integer of 0 or more.) (In the formula, n and m represent integers of 0 or more. X represents hydrogen or a methyl group.) 4. The emulsion according to claim 1, characterized in that the particle size (D50) of the dispersoid is 10 nm or more and 1 μm or less.

5. The emulsion according to claim 1, wherein the (meth)acrylic acid ester polymer contains acrylic acid as a monomer unit constituting the polymer.

6. The emulsion according to claim 1, wherein the (meth)acrylic acid ester polymer is obtained by emulsion polymerization of monomer units including the ethylene carbonate-containing acrylic monomer.

7. The emulsion according to claim 1, which contains water as a dispersion medium.

8. An article having a resin film formed from a resin composition containing the emulsion according to any one of claims 1 to 7.

9. The article according to claim 8, wherein the resin film is an adhesive layer, and the article is an adhesive sheet.

10. As a monomer unit constituting a polymer, The fine particles contain a (meth)acrylic acid ester polymer containing an ethylene carbonate-containing acrylic monomer having an ethylene carbonate structure represented by the formula:

11. The microparticles described in claim 10, characterized in that the (meth)acrylic acid ester polymer contains the ethylene carbonate-containing monomer in an amount of 50% by mass or more and 99.9% by mass or less as a monomer unit constituting the polymer.

12. The fine particles according to claim 10, wherein the ethylene carbonate-containing acrylic monomer is a compound represented by the following formula (2) or the following formula (3): (In the formula, n represents an integer of 0 or more.) (In the formula, n represents an integer of 0 or more.) 13. The fine particles according to claim 10, characterized in that the (meth)acrylic acid ester polymer contains acrylic acid as a monomer unit constituting the polymer.

14. The fine particles according to claim 10, characterized in that the average particle size is 10 nm or more and 1 μm or less.

15. The microparticles described in claim 10, characterized in that they are obtained by emulsion polymerizing monomer units containing the ethylene carbonate-containing acrylic monomer to produce an emulsion containing the (meth)acrylic acid ester polymer as a dispersoid, and then removing the dispersion medium constituting the emulsion to obtain a residue, and pulverizing the residue.

16. A resin composition containing the fine particles according to any one of claims 10 to 15.

17. An article comprising a resin film formed from the resin composition according to claim 16.

18. The article according to claim 17, wherein the resin film is an adhesive layer, and the article is an adhesive sheet.

19. As a monomer unit constituting a polymer, or fine particles containing the (meth)acrylic acid ester polymer as a dispersoid, the (meth)acrylic acid ester polymer comprising an ethylene carbonate-containing acrylic monomer having an ethylene carbonate structure as shown in the formula (I) or a resin composition comprising: a catalyst capable of nucleophilic attack on a carbon atom constituting a carbonyl group in the ethylene carbonate structure, thereby decomposing the ethylene carbonate structure and releasing carbon dioxide.

20. The resin composition according to claim 19, characterized in that the particle diameter (D50) of the dispersoid is 10 nm or more and 1 μm or less, and the average particle diameter of the fine particles is 10 nm or more and 1 μm or less.

21. The resin composition described in claim 19, characterized in that the (meth)acrylic acid ester polymer contains the ethylene carbonate-containing monomer in an amount of 10 mass % or more and 99.9 mass % or less as a monomer unit constituting the polymer.

22. The resin composition according to claim 19, wherein the ethylene carbonate-containing acrylic monomer is a compound represented by the following formula (2) or the following formula (3): (In the formula, n represents an integer of 0 or more.) (In the formula, n represents an integer of 0 or more.) 23. The catalyst is a nucleophilic anion generator capable of generating a nucleophilic anion, and the nucleophilic anion is a fluoride ion (F － ), chloride ion (Cl － ), bromide ion (Br － ), iodide ion (I － ) and hydroxide ion (OH － The resin composition according to claim 19, characterized in that the resin composition is at least one of the following:

24. The resin composition according to claim 19, wherein the catalyst is at least one of tetrabutylammonium bromide and tetra-N-butylammonium fluoride.

25. The resin composition according to claim 19, characterized in that the (meth)acrylic acid ester polymer contains acrylic acid as a monomer unit constituting the polymer.

26. The resin composition according to claim 19, characterized in that the (meth)acrylic acid ester polymer is obtained by emulsion polymerization of monomer units including the ethylene carbonate-containing acrylic monomer.

27. The resin composition described in claim 19, characterized in that the microparticles are obtained by emulsion polymerizing monomer units containing the ethylene carbonate-containing acrylic monomer to produce an emulsion containing the (meth)acrylic acid ester polymer as a dispersoid, and then removing the dispersion medium constituting the emulsion and pulverizing the residue obtained.

28. A resin film formed from the resin composition according to any one of claims 19 to 27.

29. An article comprising the resin film according to claim 28 and a member provided on at least one surface of the resin film.

30. A method for separating the resin film and the member in the article described in claim 29, comprising: a step of heating the resin film to decompose the ethylene carbonate structure and generate carbon dioxide gas; and a step of separating the resin film and the member by the carbon dioxide gas accumulated at the interface between the resin film and the member.

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