Composition for latent heat storage material

Abstract

The purpose of the present invention is to provide a composition capable of suppressing leakage of a phase transition material of a latent heat storage material from a container when the phase transition material is liquefied. The present disclosure is a composition for a latent heat storage material, the composition comprising a crosslinked polymer having a structural unit derived from an N-vinyl lactam-based monomer.

Description

Composition for latent heat storage material

[0001] The present invention relates to a latent heat storage material composition, and more particularly to a latent heat storage material composition useful for keeping things cold or warm at a constant temperature.

[0002] Latent heat storage materials are heat storage materials that store heat by utilizing latent heat associated with a phase change of a substance. Latent heat storage materials are characterized by the phase transition occurring at a constant temperature, and can store a larger amount of thermal energy than heat storage materials that use sensible heat. Therefore, they are used as heat storage materials for keeping things cool or warm at a constant temperature. Various phase transition materials and heat storage agents that transition between solid and liquid phases and exhibit latent heat storage properties have been developed. For example, Patent Document 1 discloses a method for producing a heat storage agent, which comprises polymerizing a monomer component in an oily substance having heat storage properties, and retaining the oily substance in the polymer obtained by polymerizing the monomer component so that the fluidity of the oily substance that liquefies due to the phase change is reduced.

[0003] Polymers having a lactam structure are used in a variety of applications due to their hydrophilicity and high safety to the human body and the environment, etc. In particular, crosslinked polymers having a lactam structure are useful in applications that absorb liquids such as water, and are widely used in applications such as sanitary materials such as disposable diapers, sanitary products, contact lenses, cosmetics, paints, adhesives, waterproofing agents, soil conditioners, and in the medical field, such as controlled release of drugs (see Patent Documents 2 to 4).

[0004] Japanese Patent Laid-Open No. 10-60423 Japanese Patent Laid-Open No. 10-5582 Japanese Patent Laid-Open No. 2002-212374 Japanese Patent Laid-Open No. 2022-51996

[0005] Although various latent heat storage materials have been developed to date, there is a problem in that phase-change materials, which transition between solid and liquid phases, flow when liquefied, causing the phase-change material to leak out of the container. Therefore, there has been a need for technology that can reduce leakage of phase-change materials from their containers even when the phase-change material is liquefied.

[0006] The present invention has been made in consideration of the above-mentioned current situation, and aims to provide a composition that can suppress leakage of a phase change material from a container when the phase change material of a latent heat storage material is liquefied.

[0007] The present inventors have conducted extensive research into compositions for latent heat storage materials and have found that a composition containing a crosslinked polymer having structural units derived from an N-vinyl lactam monomer reduces the fluidity of a phase change material, thereby preventing leakage of the phase change material even when the phase change material is liquefied when used as a latent heat storage material. This led to the realization that the above-mentioned problems could be successfully solved, and has led to the present invention.

[0008] The present invention includes the following compositions for latent heat storage materials, etc.: [1] A composition for latent heat storage materials, comprising a crosslinked polymer having structural units derived from an N-vinyl lactam monomer. [2] The composition for latent heat storage materials according to [1] above, wherein the crosslinked polymer has a structure derived from a crosslinking agent, and the crosslinking agent is a compound having two or more ethylenically unsaturated bonds. [3] The latent heat storage material composition according to [1] or [2] above, wherein the crosslinked polymer has a structure derived from a crosslinking agent, and the crosslinking agent comprises at least one selected from the group consisting of a crosslinkable monomer having a cyanuric acid skeleton, pentaerythritol (di-, tri-, tetra-)(meth)allyl ether, triallyl isocyanurate, triallyl phosphate, triallylamine, diallyl carbonate, 1,3-bis(allyloxy)-2-propanol, divinylethylene urea, 1,4-butylene bis(N-vinylamide), and (di-, tri-, tetra-, penta-, hexa-, hepta-, octa-)allylsucrose. [4] The latent heat storage material composition according to [2] or [3] above, wherein the proportion of the structure derived from the crosslinking agent is 0.01 to 2 mol % relative to 100 mol % of all structural units. [5] The latent heat storage material composition according to any one of [1] to [4] above, wherein the crosslinked polymer has an average particle size of 10 to 1000 μm. [6] A latent heat storage material comprising the latent heat storage material composition according to any one of [1] to [5] above and a phase change material. [7] The latent heat storage material according to [6] above, wherein the phase change material is an inorganic salt solution, and / or at least one selected from the group consisting of alcohols, hydrocarbons, fatty acids, esters, ethers, silicone oils, and fluorocarbons.

[0009] The latent heat storage material composition of the present invention has the above-mentioned configuration and reduces the fluidity of the phase change material used in the latent heat storage material, thereby preventing leakage of the phase change material even when the phase change material is liquefied when made into a latent heat storage material, and therefore can be suitably used as a latent heat storage material, etc.

[0010] Preferred embodiments of the present invention will be specifically described below, but the present invention is not limited to the following description and can be appropriately modified and applied within the scope of the present invention. Note that a combination of two or more of the individual preferred embodiments of the present invention described below also falls within the scope of the present invention.

[0011] [Latent Heat Storage Material Composition] The latent heat storage material composition of the present invention contains a crosslinked polymer having structural units derived from an N-vinyl lactam monomer (hereinafter referred to as an N-vinyl lactam crosslinked polymer, or simply as a crosslinked polymer). The polymer in the composition reduces the fluidity of the phase change material used in the latent heat storage material, and can suppress leakage of the phase change material even when the phase change material of the latent heat storage material is liquefied.

[0012] The content of the crosslinked polymer having a structural unit derived from an N-vinyl lactam monomer in the latent heat storage material composition is not particularly limited, but is preferably 50 to 100% by mass, more preferably 70 to 100% by mass, even more preferably 80 to 100% by mass, and particularly preferably 90 to 100% by mass, relative to 100% by mass of the latent heat storage material composition.

[0013] The latent heat storage material composition may contain other components in addition to the crosslinked polymer. The proportion of the other components in the latent heat storage material composition is not particularly limited, but is preferably 0 to 50% by mass, more preferably 0 to 30% by mass, even more preferably 0 to 20% by mass, and particularly preferably 0 to 10% by mass, relative to 100% by mass of the latent heat storage material composition.

[0014] <N-vinyl lactam crosslinked polymer> The latent heat storage material composition of the present invention is a crosslinked polymer having structural units derived from an N-vinyl lactam monomer, which absorbs and gels various liquids used as phase change materials, thereby preventing leakage of the phase change material even when the phase change material of the latent heat storage material is liquefied. The present invention also relates to a gelling agent for phase change materials, which includes a polymer having structural units derived from the N-vinyl lactam monomer.

[0015] The crosslinked polymer has a structural unit derived from an N-vinyl lactam monomer. In the present invention, the term "structural unit derived from an N-vinyl lactam monomer" generally refers to a structural unit having the same structure as a structural unit formed by polymerization of an N-vinyl lactam monomer. Note that the structural unit having the same structure as a structural unit formed by polymerization of an N-vinyl lactam monomer is not limited to only structural units formed by actual polymerization of an N-vinyl lactam monomer, but also includes structural units formed by other methods as long as they have the same structure as a structural unit formed by polymerization of an N-vinyl lactam monomer. The structural unit derived from an N-vinyl lactam monomer is preferably a structural unit in which one, or when two or more, ethylenically unsaturated bonds contained in the N-vinyl lactam monomer are replaced with a carbon-carbon single bond (hereinafter also simply referred to as a single bond).

[0016] The crosslinked polymer is not particularly limited as long as it has a crosslinked structure with structural units derived from an N-vinyl lactam monomer, but the content of structural units derived from an N-vinyl lactam monomer is preferably 30 to 100 mol%, more preferably 50 to 100 mol%, even more preferably 70 to 100 mol%, even more preferably 80 to 100 mol%, particularly preferably 90 to 100 mol%, and most preferably 100 mol%, relative to 100 mol% of all structural units (structural units derived from N-vinyl lactam monomers and structural units derived from other monomers described below).

[0017] The crosslinked polymer may have structural units derived from monomers other than N-vinyl lactam monomers, and the proportion thereof is not particularly limited, but is preferably 0 to 70 mol %, more preferably 0 to 50 mol %, even more preferably 0 to 30 mol %, still more preferably 0 to 20 mol %, particularly preferably 0 to 10 mol %, and most preferably 0 mol %, relative to 100 mol % of all structural units.

[0018] The crosslinked polymer preferably has a structure derived from the crosslinking agent. A preferred embodiment of the present invention is one in which the crosslinked polymer has a structure derived from the crosslinking agent. When the crosslinked polymer has a structure derived from the crosslinking agent, the phase change material that has absorbed the liquid can be gelled, thereby more effectively suppressing leakage of the phase change material. In the present invention, the "structure derived from the crosslinking agent" generally refers to a structure identical to the structure formed by polymerization of the crosslinking agent. Note that the "structure identical to the structure formed by polymerization of the crosslinking agent" is not limited to a structure formed by actual polymerization of the crosslinking agent, but also includes structures formed by other methods as long as they have the same structure as the structure formed by polymerization of the crosslinking agent. The crosslinked polymer preferably has a structure in which one or more ethylenically unsaturated bonds in the crosslinking agent are replaced with single bonds. More preferably, the crosslinked polymer has a structure in which two or more ethylenically unsaturated bonds in the crosslinking agent are replaced with single bonds.

[0019] The proportion of structures derived from the crosslinking agent in the crosslinked polymer is not particularly limited, but is preferably 0.01 to 2 mol% relative to 100 mol% of all structural units. This allows the phase change material to gel to an optimal hardness while maintaining the liquid absorption capacity of the phase change material. It is more preferably 0.05 to 1.5 mol%, even more preferably 0.06 to 1.4 mol%, even more preferably 0.08 to 1.2 mol%, and particularly preferably 0.1 to 1 mol%. In one aspect, an embodiment in which the proportion of structures derived from the crosslinking agent is 0.2 to 0.8 mol% is also one of the preferred embodiments of the present invention. Note that, in this specification, the term "total structural units" refers to structural units derived from N-vinyl lactam monomers and structural units derived from the other monomers, and does not include structures derived from the crosslinking agent.

[0020] The average particle size of the crosslinked polymer is not particularly limited, but is preferably 10 to 1,000 μm. An average particle size of 10 μm or more can more sufficiently prevent the occurrence of lumps when the phase change material absorbs liquid, while an average particle size of 1,000 μm or less can more sufficiently prevent a decrease in the liquid absorption rate of the phase change material. The average particle size of the crosslinked polymer is more preferably 30 to 800 μm, even more preferably 50 to 600 μm, and particularly preferably 100 to 500 μm. The average particle size of the crosslinked polymer is a value measured using a dry particle size distribution analyzer (Malvern Division, Spectris Co., Ltd., Model: Mastersizer 3000, Dry). Alternatively, in the case of coarse particles that cannot be measured using a particle size distribution analyzer or in the case of a crosslinked polymer in the form of a rectangular parallelepiped or other molded product, the average particle size is measured using a ruler.

[0021] (N-vinyl lactam monomer) The N-vinyl lactam monomer is not particularly limited as long as it is a monomer having an N-vinyl lactam structure, but may be a monomer represented by the following formula (1):

[0022]

[0023] (In the formula, R １ , R ２ , R ３ , R ４ are the same or different and represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms which may have a substituent. x represents an integer of 0 to 4. y represents an integer of 1 to 3.

[0024] When the N-vinyl lactam monomer has a structure represented by the formula (1), the structural unit derived from the N-vinyl lactam monomer in the crosslinked polymer has a structure represented by the following formula (2):

[0025]

[0026] (In the formula, R １ , R ２ , R ３ , R ４are the same or different and represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms which may have a substituent. x represents an integer of 0 to 4. y represents an integer of 1 to 3. The asterisk represents an atom contained in another structural unit of the same type or a different type to which the structural unit represented by formula (2) is bonded.

[0027] The above R １ ~R ４ The number of carbon atoms in the alkyl group in the above R is preferably 1 to 6, more preferably 1 to 4. The alkyl group is more preferably a methyl group or an ethyl group, and particularly preferably a methyl group. １ ~R ４ The substituent in the above formula (1) is not particularly limited, but examples thereof include an ethylenically unsaturated hydrocarbon group; a carboxyl group, a sulfonic acid group, and their esters and salts; and a reactive functional group capable of condensation reaction with a crosslinking agent, such as an amino group or a hydroxyl group. １ ~R ４ When at least one of R is an alkyl group having 1 to 10 carbon atoms and having, as a substituent, a reactive functional group capable of undergoing a condensation reaction with a crosslinking agent having a plurality of reactive functional groups, as described below, a crosslinked structure can be formed by a post-crosslinking step or the like, as described below, in the method for producing a crosslinked polymer. １ ~R ３ is preferably a hydrogen atom. ４ is preferably a hydrogen atom or a methyl group, more preferably a hydrogen atom. x is preferably an integer of 0 to 2, more preferably an integer of 0 to 1, and most preferably 0. y is preferably 1 or 2, more preferably 1.

[0028] Examples of the compound represented by formula (1) include N-vinylpyrrolidone, N-vinyl-5-methylpyrrolidone, N-vinylpiperidone, N-vinylcaprolactam, 1-(2-propenyl)-2-pyrrolidone, etc., and one or more of these can be used. As the N-vinyllactam, an unsaturated monomer having a pyrrolidone ring is preferred. N-vinylpyrrolidone is more preferred.

[0029] (Other Monomers) The crosslinked polymer may have structural units derived from other monomers other than N-vinyl lactam monomers. The other monomers are not particularly limited, and examples thereof include: (i) unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid, and salts thereof; (ii) unsaturated dicarboxylic acids such as fumaric acid, maleic acid, methylene glutaric acid, and itaconic acid, and salts thereof (which may be monosalts or disalts); (iii) unsaturated sulfonic acids such as 3-allyloxy-2-hydroxypropanesulfonic acid, (meth)allylsulfonic acid, and isoprene sulfonic acid; (iv) unsaturated alcohols such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, 3-(meth)allyloxy-1,2-dihydroxypropane, (meth)allyl alcohol, isoprenol, and the like, and alkylene oxide adducts in which alkylene oxide is added to the hydroxyl groups of these alcohols; (v) (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and cyclohexyl (meth)acrylate; (vi) (meth)acrylamide (vii) vinyl aryl monomers such as styrene, indene, vinylaniline, etc.; (viii) alkenes such as ethylene, propylene, butadiene, isobutylene, octene, etc.; (ix) vinyl carboxylates such as vinyl acetate, vinyl propionate, etc.; (x) N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylamide ... (xi) unsaturated amines such as vinylamide, vinylpyridine, vinylimidazole, and salts or quaternized products thereof; (xi) vinylamides such as vinylformamide, vinylacetamide, vinyloxazolidone; (xii) unsaturated anhydrides such as maleic anhydride, itaconic anhydride; (xiii) vinyl ethylene carbonate and derivatives thereof; (xiv) ethyl (meth)acrylic acid-2-sulfonate and derivatives thereof; (xv) vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, etc. Among these, nonionic monomers are preferred.Specifically, the monomers are (iv), (v), (vi), (vii), (ix), (xi), (xiii), and (xv), and more preferably (iv), (v), and (vi). These may be used alone or in combination of two or more. Examples of the salts in (i) to (iii), and (x) above include metal salts, ammonium salts, and organic amine salts. Examples of the alkylene oxide in (iv) above include ethylene oxide and propylene oxide, and alkylene oxides having 1 to 20 carbon atoms are preferred, and alkylene oxides having 1 to 4 carbon atoms are more preferred. The number of moles of alkylene oxide added in (iv) above is preferably 0 to 50 moles, more preferably 0 to 20 moles, per mole of the compound in (iv) above.

[0030] (Crosslinking Agent) The crosslinking agent is not particularly limited as long as it can crosslink the polymer, and examples thereof include a crosslinkable monomer copolymerizable with the monomer component constituting the polymer, and a compound having a plurality of reactive functional groups capable of reacting with the reactive functional group possessed by the polymer. The crosslinking agent is preferably a crosslinkable monomer copolymerizable with an N-vinyl lactam monomer or the like. The crosslinking agent is more preferably a compound (crosslinkable monomer) having two or more ethylenically unsaturated bonds. When a compound having an ethylenically unsaturated bond is used as the crosslinking agent, the structure derived from the crosslinking agent in the crosslinked polymer is a structure in which the ethylenically unsaturated bond possessed by the crosslinking agent is replaced with a single bond. The structure in which the ethylenically unsaturated bond of the crosslinking agent having an ethylenically unsaturated bond is replaced with a single bond is represented by the following formula (3-1);

[0031]

[0032] (In the formula, R １ , R ２ , R ３are the same or different and represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms which may have a substituent. m represents an integer of 0 to 4. Z represents an organic group having 1 to 20 carbon atoms. An asterisk represents an atom contained in another structural unit of the same or different type to which the structure represented by formula (3-1) is bonded. W is the same or different and represents a bonding site between the structure represented by formula (3-1) and another structural unit in the crosslinked polymer, and is represented by the following formula (4) or (5):

[0033] (In the formula, R １’ , R ２’ , R ３’ are the same or different and represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms which may have a substituent. An asterisk represents an atom contained in another structural unit of the same or different type to which the structure represented by formula (3-1) is bonded. ) can be represented by the following formula: p represents an integer of 1 to 7. ) can be represented by the following formula:

[0034] The organic group having 1 to 20 carbon atoms represented by Z is not particularly limited, and may have a heteroatom such as an oxygen atom, a nitrogen atom, or a phosphorus atom. Examples of Z include hydrocarbon groups having a heteroatom-containing structure such as an ether group, a hydroxyl group, an amide group, a carbonyl group, an amine structure, a carbonyl group, a heterocyclic structure, a ureido group, a carbonate group, or a phosphate ester group. Z is preferably a hydrocarbon group having an oxygen atom and / or a nitrogen atom, and more preferably has at least one heteroatom-containing structure selected from the group consisting of an ether group, a hydroxyl group, an amide group, a carbonyl group, an amine structure, a ureido group, a carbonate group, a phosphate ester group, and a heterocyclic structure having a nitrogen atom.

[0035] The Ws may be the same or different and represent bonding sites between the structure represented by formula (3-1) and other structural units in the crosslinked polymer, and can be represented by formula (4) or (5). For example, when the crosslinking agent has two ethylenically unsaturated bonds, W is a structure represented by formula (4) and p is 1. For example, when the crosslinking agent has one ethylenically unsaturated bond and two reactive functional groups other than ethylenically unsaturated bonds, W is a structure represented by formula (5) and p is 2.

[0036] The W is preferably a structure represented by formula (4). １’ , R ２’ , R ３’ are the same or different and represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms which may have a substituent, and preferred embodiments of these are １ , R ２ , R ３ is the same as:

[0037] The above-mentioned p is preferably 1 to 6, more preferably 1 to 5, still more preferably 1 to 4, particularly preferably 1 to 3, and most preferably 2.

[0038] One preferred embodiment of the structure in which the ethylenically unsaturated bond of the crosslinking agent is replaced with a single bond is represented by the following formula (3-2):

[0039]

[0040] (In the formula, R １ , R ２ , R ３ are the same or different and represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms which may have a substituent. m represents an integer of 0 to 4. Z １ represents an organic group having 1 to 20 carbon atoms. An asterisk represents an atom contained in another structural unit of the same type or a different type to which the structural unit represented by formula (3-2) is bonded. W １ are the same or different and represent the bonding site between the structure represented by formula (3-2) and other structural units in the crosslinked polymer, and can be represented by the above formula (4) or (5). １ represents an integer of 1 to 7.

[0041] Above Z １ The organic group having 1 to 20 carbon atoms in the above formula is not particularly limited, and may have a heteroatom such as an oxygen atom, a nitrogen atom, or a phosphorus atom. １is preferably a hydrocarbon group having a heteroatom-containing structure, more preferably a hydrocarbon group having at least one heteroatom selected from the group consisting of an oxygen atom, a nitrogen atom, and a phosphorus atom, even more preferably a hydrocarbon group having at least one heteroatom-containing structure selected from the group consisting of an ether group, a hydroxyl group, an amide group, a carbonyl group, an amine structure, a ureido group, a carbonate group, a phosphate ester group, and a heterocyclic structure having a nitrogen atom, even more preferably a hydrocarbon group having at least one heteroatom-containing structure selected from the group consisting of an ether group, a hydroxyl group, a phosphate ester structure, a carbonate group, and a heterocyclic structure having a nitrogen atom, and particularly preferably a hydrocarbon group having a triazine structure.

[0042] The above W １ The structure represented by the above formula (4) is preferred as the p １ is preferably 1 to 6, more preferably 1 to 5, even more preferably 1 to 4, particularly preferably 1 to 3, and most preferably 2.

[0043] Another preferred embodiment of the structure in which the double bond of the crosslinking agent having an ethylenically unsaturated bond is replaced with a single bond is represented by the following formula (3-3):

[0044]

[0045] (In the formula, R １ , R ２ , R ３ are the same or different and represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms which may have a substituent. m represents an integer of 0 to 4. Z ２ , Z ３ are the same or different and represent a hydrogen atom or an organic group having 1 to 20 carbon atoms. ２ , Z ３ At least one of Z is an organic group. ２ and Z ３ may be bonded to each other to form a ring structure. An asterisk represents an atom contained in another structural unit of the same or different type to which the structural unit represented by formula (3-3) is bonded. W ２ , W ３are the same or different and represent the bonding site between the structure represented by formula (3-3) and other structural units in the crosslinked polymer, and can be represented by the above formula (4) or (5). ２ , p ３ are the same or different and represent an integer of 0 to 7. ２ , p ３ At least one of Z is an integer of 1 or more. ２ , Z ３ When one of the groups is a hydrogen atom, Z ２ or Z ３ p corresponding to ２ or p ３ is 0.)

[0046] Above Z ２ , Z ３ are the same or different and are a hydrogen atom or an organic group having 1 to 20 carbon atoms, and Z ２ , Z ３ At least one of the above may be an organic group, and the organic group may have a heteroatom. ２ , Z ３ may each be a linear or cyclic organic group; Z ２ and Z ３ may be bonded to each other to form a cyclic organic group. ２ , Z ３ In one embodiment, the organic group having 1 to 20 carbon atoms preferably has a heteroatom-containing structure. ２ and Z ３ are bonded to each other to form a ring structure having an amide structure, Z ２ is a hydrogen atom or a hydrocarbon group having a carbonyl structure and / or an amide structure, Z ３ is a hydrocarbon group having a carbonyl structure and / or an amide structure, or Z ２ , Z ３ are each a hydrocarbon group such as an alkylene group.

[0047] The above W ２ , W ３ The structure represented by the above formula (4) is preferred as the p ２ , p ３are the same or different and represent an integer of 0 to 7. ２ , p ３ At least one of Z is an integer of 1 or more. ２ , Z ３ When one of the groups is a hydrogen atom, Z ２ or Z ３ p corresponding to ２ or p ３ is 0. ２ and p ３ The total is preferably 1 to 6, more preferably 1 to 5, even more preferably 1 to 4, particularly preferably 1 to 3, and most preferably 1 to 2.

[0048] Examples of crosslinkable monomers having two or more ethylenically unsaturated bonds include crosslinkable monomers having a cyanuric acid skeleton, such as triallyl cyanurate; N,N'-alkylene bis(meth)acrylamides having an alkylene group having 1 to 4 carbon atoms, such as N,N'-methylene bis(meth)acrylamide; alkylene bis(N-vinylamides) having an alkylene group having 1 to 6 carbon atoms, such as 1,4-butylene bis(N-vinylamide); and alkylene bis(N-vinylamides) having an alkylene group having 1 to 4 carbon atoms, such as (poly)ethylene glycol di(meth)acrylate and (poly)propylene glycol di(meth)acrylate. (poly)alkylene glycol di(meth)acrylates; trimethylolpropane (di, tri)(meth)acrylates which may be modified with an alkylene oxide having an alkylene group having 1 to 4 carbon atoms, such as trimethylolpropane tri(meth)acrylate, trimethylolpropane di(meth)acrylate, and ethylene oxide-modified trimethylolpropane tri(meth)acrylate; glycerin (di, tri)(meth)acrylates such as glycerin tri(meth)acrylate and glycerin acrylate methacrylate; pentaerythritol tetra( dipentaerythritol (di, tri, tetra, penta, hexa) (meth)acrylates such as dipentaerythritol hexa(meth)acrylate; pentaerythritol (di, tri, tetra) (meth)allyl ethers such as pentaerythritol tri(meth)allyl ether; triallyl compounds having 9 to 20 carbon atoms such as triallyl isocyanurate, triallyl phosphate, and triallylamine; diallyl carbonate, 1,3-bis(allyloxy)-2-propanol, etc. Examples of such compounds include diallyl compounds having 6 to 20 carbon atoms; (di, tri)vinyl compounds having 4 to 20 carbon atoms, such as divinyl ether, divinyl ketone, trivinylbenzene, divinylethylene urea, divinyltoluene, and divinylxylene; diisocyanates having 2 to 20 carbon atoms, such as tolylene diisocyanate and hexamethylene diisocyanate; poly(meth)allyloxyalkanes, N,N'-divinyl-2-imidazolidinone, N,N'-1,4-butylenebis(N-divinylacetamide), and (di, tri, tetra, penta, hexa, hepta, octa)allylsucrose.These may be used alone or in combination of two or more. Among the above-mentioned crosslinking agents, it is preferable to use a compound having two or more allyl groups, since the amount of residual N-vinyl lactam and the soluble content (the non-crosslinked polymer content that dissolves in water) tend to decrease. Specifically, crosslinking monomers having a cyanuric acid skeleton, pentaerythritol (di-, tri-, tetra-)(meth)allyl ether, triallyl isocyanurate, triallyl phosphate, triallylamine, diallyl carbonate, 1,3-bis(allyloxy)-2-propanol, divinylethyleneurea 1,4-butylenebis(N-vinylamide), and (di-, tri-, tetra-, penta-, hexa-, hepta-, octa-)allylsucrose are preferred. Crosslinking monomers having a cyanuric acid skeleton are more preferred. The crosslinking monomer having a cyanuric acid skeleton is not particularly limited as long as it has a structure derived from cyanuric acid and at least two ethylenically unsaturated bonds, but examples thereof include those represented by the following formula (6):

[0049]

[0050] (In the formula, R １ , R ２ , R ３ are the same or different and represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms which may have a substituent. m are the same or different and represent an integer of 0 to 4. When the above-mentioned crosslinkable monomer having a cyanuric acid skeleton is used as the crosslinking agent, the structure derived from the crosslinking agent is preferably a monomer represented by the following formula (7);

[0051]

[0052] (In the formula, R １ , R ２ , R ３ are the same or different and represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms which may have a substituent. m is the same or different and represents an integer of 0 to 4. An asterisk represents an atom contained in another structural unit of the same type or different type to which the structural unit represented by formula (7) is bonded.

[0053] The above R １ ~R ３The number of carbon atoms in the alkyl group in the above R is preferably 1 to 6, more preferably 1 to 4. The alkyl group is more preferably a methyl group or an ethyl group, and particularly preferably a methyl group. １ ~R ３ The substituent in R is not particularly limited, but examples thereof include ethylenically unsaturated hydrocarbon groups; carboxyl groups, sulfonic acid groups and their esters and salts; and reactive functional groups capable of condensation reaction with a crosslinking agent, such as amino groups and hydroxyl groups. １ ~R ３ is preferably a hydrogen atom. m is preferably 0, 1 or 2, more preferably 1. The compound represented by the above formula (6) is preferably triallyl cyanurate.

[0054] (Method for Producing Crosslinked Polymer) The method for producing the crosslinked polymer is not particularly limited, but it is preferable to produce the crosslinked polymer by polymerizing a component containing an N-vinyl lactam monomer and a crosslinking agent. That is, a method for producing an N-vinyl lactam crosslinked polymer comprising a step of polymerizing a component containing an N-vinyl lactam monomer and a crosslinking agent also constitutes one aspect of the present invention. Specific and preferred examples of the monomer components and crosslinking agents are as described above. The content ratio of each monomer and crosslinking agent relative to 100 mol % of all monomer components (N-vinyl lactam monomer and other monomers) is the same as the content ratio of each structural unit relative to 100 mol % of all structural units described above. The purity of the N-vinyl lactam monomer used in the polymerization step is preferably 90% or higher, more preferably 95% or higher, even more preferably 98% or higher, and most preferably 99% or higher.

[0055] The polymerization may be carried out in the absence of a solvent or in the presence of a solvent. The polymerization may be carried out by various conventionally known methods, such as bulk polymerization, solution polymerization, suspension polymerization, reverse-phase suspension polymerization, emulsion polymerization, reverse-phase emulsion polymerization, precipitation polymerization, or cast polymerization, thin film polymerization, spray polymerization, etc. The preferred polymerization method is solution polymerization. By carrying out solution polymerization, particularly when a crosslinking agent is used, uneven crosslinking in the crosslinked polymer can be suppressed. The stirring method used in the polymerization reaction is not particularly limited, but when a gel-like crosslinked polymer is produced, it is more preferable to use a double-arm kneader as a stirring device and stir while breaking it up by the shear force of the double-arm kneader. The polymerization process may be carried out either batchwise or continuously.

[0056] In the polymerization step, methods for initiating polymerization of the monomer component containing N-vinyl lactam include a method of adding a polymerization initiator, a method of irradiating with UV light, a method of applying heat, and a method of irradiating with light in the presence of a photoinitiator.

[0057] When a solvent is used in the polymerization step, examples of the solvent include one or more selected from alcohols such as water, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butyl alcohol, diethylene glycol, etc. From the viewpoint of the safety of the resulting composition, it is preferable to use water as the solvent, and in this case, the solvent substitution step and the like can be omitted, thereby improving productivity.

[0058] In the polymerization step, it is preferable to use a polymerization initiator when carrying out polymerization. Examples of the polymerization initiator include peroxides such as hydrogen peroxide and t-butyl hydroperoxide; persulfates such as sodium persulfate, potassium persulfate and ammonium persulfate; dimethyl 2,2'-azobis(2-methylpropionate), 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2-methylpropionamidine) dihydrochloride, 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]hydrate, 2,2'-azobis[2-(2-imidazolin-2-yl)propane], 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride, 2,2'-azobis[2-(2-isopropyl)propane] ... Suitable initiators include azo compounds such as 2,2'-azobis(1-imino-1-pyrrolidino-2-methylpropane) disulfate hydrate, 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine] n-hydrate, and 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide]; organic peroxides such as benzoyl peroxide, lauroyl peroxide, peracetic acid, di-t-butyl peroxide, and cumene hydroperoxide; and redox initiators that generate radicals by combining an oxidizing agent and a reducing agent, such as ascorbic acid and hydrogen peroxide, sodium sulfoxylate and t-butyl hydroperoxide, and persulfates and metal salts. Of these polymerization initiators, hydrogen peroxide, persulfates, and azo compounds are preferred, with azo compounds being most preferred. Among these, 2,2'-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane], 2,2'-azobis[2-(2-imidazolin-2-yl)propane]disulfate hydrate, 2,2'-azobis(2-methylpropionamidine)dihydrochloride, and 2,2'-azobis(2-methylbutyronitrile) are more preferred. These polymerization initiators may be used alone or in the form of a mixture of two or more.

[0059] The amount of the polymerization initiator used is preferably 0.1 g or more and 10 g or less per mole of the total amount of the monomer and crosslinking agent used. By using 0.1 g or more of the polymerization initiator, the proportion of unreacted monomer contained in the resulting crosslinked polymer can be sufficiently reduced, and the amount of by-products derived from the unreacted monomer, such as the compound represented by formula (8) described below, can also be sufficiently suppressed. Furthermore, by using 10 g or less of the initiator, the proportion of impurities contained in the resulting crosslinked polymer can be sufficiently reduced. Furthermore, by using such an amount of the initiator, coloration of the resulting crosslinked polymer can also be suppressed. That is, a method for producing a crosslinked polymer in which a polymerization initiator is used in the polymerization step and the amount of the polymerization initiator used is 0.1 to 10 g per mole of the total amount of the monomer and crosslinking agent also constitutes one aspect of the present invention. The amount of the polymerization initiator used is more preferably 0.1 g or more and 7 g or less, and even more preferably 0.1 g or more and 5 g or less.

[0060] Specific examples of suitable dispersants when reverse phase suspension polymerization is employed in the polymerization step include sorbitan fatty acid esters, sucrose fatty acid esters, glycerin fatty acid esters, polyglycerin fatty acid esters, cellulose esters such as ethyl cellulose and cellulose acetate, cellulose ethers, and carboxyl group-containing polymers such as α-olefin-maleic anhydride copolymers. These dispersants may be used alone or in an appropriate mixture of two or more. The hydrophobic organic solvent used when reverse phase suspension polymerization is employed is not particularly limited.

[0061] In the polymerization step, the atmosphere during polymerization is not particularly limited, but it is preferable to carry out the polymerization under an inert gas (nitrogen, argon, etc.) atmosphere. By carrying out the polymerization under an inert gas atmosphere, it is possible to improve the crushing efficiency of the obtained crosslinked polymer, reduce the proportion of unreacted monomers contained in the obtained crosslinked polymer, and shorten the reaction time between the organic acid and the crosslinked polymer when the organic acid is added to the crosslinked polymer.

[0062] In the polymerization step, the polymerization temperature is not particularly limited, but a relatively low temperature is preferred because the molecular weight of the crosslinked polymer increases, and a temperature in the range of 20° C. to 100° C. is more preferred because the polymerization rate improves. The reaction time may be appropriately set depending on the reaction temperature, the types (properties), combinations, amounts used, etc. of the monomer components, polymerization initiator, and solvent so that the polymerization reaction is completed.

[0063] The material of the reaction vessel in which the polymerization step is carried out is not particularly limited as long as it is capable of carrying out the polymerization step, but it is preferable to use a reaction vessel made of a material such as stainless steel. By carrying out the polymerization reaction using a reaction vessel made of such a material that easily transfers heat, the polymerization reaction can be sufficiently progressed, and the content of unreacted monomers (unsaturated monomers having a lactam structure, etc.) contained in the obtained crosslinked polymer can be reduced. It is also preferable to use a reaction vessel made of a material that does not elute iron, such as polypropylene, and by using a reaction vessel made of such a material, the content of iron contained in the obtained crosslinked polymer can be reduced.

[0064] The crosslinked polymer of the present invention may be produced by including any step in addition to the polymerization step, such as a gel-crushing step, a drying step, a pulverization step, a classification step, a granulation step, a post-crosslinking step, etc.

[0065] When the crosslinked polymer is obtained by polymerization using a solvent and is in a gel state, i.e., when it is a gel polymer containing a solvent, it is preferable to produce it by including a gel crushing step. The gel crushing step is not particularly limited as long as it can finely granulate the gel crosslinked polymer containing a solvent, and can be carried out, for example, using a crusher (kneader, meat chopper, etc.).

[0066] The crosslinked polymer is preferably produced by including a drying step. In particular, when the crosslinked polymer is obtained by polymerization using a solvent and is in a gel state, i.e., when it is a solvent-containing gel crosslinked polymer, it is preferable to provide a step of drying the gel crosslinked polymer or the particulate gel crosslinked polymer obtained by the gel crushing step. Drying refers to an operation to increase the solid content. Typically, the ratio of solid content to the total weight of the crosslinked polymer is increased compared to before drying. Preferably, the solid content is increased to 95% by mass or more, more preferably 96% by mass or more, based on 100% by mass of the total weight of the crosslinked polymer. The upper limit of the solid content is preferably about 99% by mass. Drying may be performed simultaneously with polymerization, or drying during polymerization and drying after polymerization may be combined. More preferably, a drying step is provided in which the polymer is dried using a drying device after polymerization. Here, the solid content of the crosslinked polymer refers to a value measured by the following method. Approximately 1 g of cross-linked polymer (mass W2 (g)) is weighed into a weighing can (mass W1 (g)) with a bottom diameter of approximately 5 cm, and left to stand in a constant temperature dryer at 150°C for 1 hour to dry. After drying, the mass (W3 (g)) of the weighing can + cross-linked polymer is measured, and the solid content is calculated using the following formula: Solid content (mass %) = ((W3 (g) - W1 (g)) / W2 (g)) x 100

[0067] The drying step is preferably carried out for at least 50% of the total drying time, more preferably in the range of 80°C to 250°C throughout substantially the entire drying step. Keeping the temperature within this range tends to further improve the physical properties of the crosslinked polymer. The drying temperature is determined by the heat medium temperature, but if it cannot be determined by the heat medium temperature, such as microwaves, it is determined by the material temperature. The drying method is not particularly limited as long as the drying temperature is within the above range, and hot air drying, windless drying, reduced-pressure drying, infrared drying, microwave drying, etc. can be suitably used. Among these, hot air drying is more preferred. When hot air drying is used, the drying air volume is preferably in the range of 0.01 to 10 m / sec, more preferably 0.1 to 5 m / sec. The drying temperature range is more preferably 110°C to 220°C, and even more preferably 120°C to 200°C. Drying may be carried out at a constant temperature or by varying the temperature, but it is preferable that substantially all drying steps be carried out within the above temperature range.

[0068] The above-mentioned production method preferably includes a pulverization step. By performing the pulverization step, the average particle size and aspect ratio of the crosslinked polymer can be adjusted to a more suitable range. When the production method of the present invention includes a drying step, pulverization may be performed before, during, or after drying, but is preferably performed after drying. More preferably, the pulverization step is performed after the gel-crushing step and the drying step. The above-mentioned pulverization step is preferably performed using a pulverizer. The pulverizer is not particularly limited, but examples include roll-type pulverizers such as roll mills, hammer-type pulverizers such as hammer mills, impact pulverizers, cutter mills, turbo grinders, ball mills, pin mills, flash mills, and jet mills such as fluidized bed jet mills and target jet mills. To pulverize the material to a smaller average particle size range, it is more preferable to use a target jet mill. In addition, to control the particle size distribution, it is also preferable to use a roll mill, hammer-type pulverizer, impact pulverizer, pin mill, or jet mill. In order to control the particle size distribution, it is more preferable to pulverize the material two or more times consecutively, and even more preferably three or more times consecutively. In addition, when pulverizing the material two or more times, the pulverizers used for each pulverization step may be the same or different. It is also possible to use a combination of different types of pulverizers. The pulverization method in the pulverization step is not particularly limited, and pulverization at room temperature or freeze-pulverization may be used. Since the N-vinyl lactam crosslinked polymer is soft, freeze-pulverization is preferred, but by using the target-type jet mill, it is possible to pulverize more finely even at room temperature, and production costs can be reduced compared to freeze-pulverization. Furthermore, by using the target-type jet mill, the classification step described below can be omitted, further improving productivity.

[0069] For example, a classification step or a granulation step may be provided in order to adjust the average particle size of the crosslinked polymer of the present invention to a more suitable range and / or to control the particle size distribution to a specific range. A sieve with a specific mesh size may be used for the classification. The classifier used for classification with a sieve is not particularly limited, and examples thereof include a vibrating sieve (unbalanced weight-driven type, resonance type, vibration motor type, electromagnetic type, circular vibration type, etc.), an in-plane motion sieve (horizontal motion type, horizontal circular-linear motion type, three-dimensional circular motion type, etc.), a movable mesh sieve, a forced stirring type sieve, a mesh surface vibration sieve, a wind sieve, and an ultrasonic sieve. A vibrating sieve or an in-plane motion sieve is preferably used.

[0070] In the method for producing the crosslinked polymer, a post-crosslinking step for forming the crosslinked structure may be carried out after the polymerization step of polymerizing the monomer components. Examples of the method for post-crosslinking (crosslinking after polymerization) in the post-crosslinking step include (i) a method of irradiating the polymer obtained in the polymerization step with UV, gamma rays, or electron beams, (ii) a method of adding a reaction accelerator such as a condensing agent to the polymer obtained in the polymerization step to cause self-crosslinking, (iii) a method of applying heat to the polymer obtained in the polymerization step to cause self-crosslinking, (iv) a method of adding a radical generator to the polymer obtained in the polymerization step and then applying heat to cause self-crosslinking, and (v) a method of adding a radical polymerizable crosslinking agent (crosslinkable monomer) and a radical polymerization initiator to the polymer obtained in the polymerization step and then heating and / or irradiating with light.

[0071] In the production of the crosslinked polymer of the present invention, when a crosslinked structure is formed by reacting a polymer obtained by polymerizing a monomer component containing a monomer having a reactive functional group with a crosslinking agent having multiple functional groups reactive with the reactive functional group, the amount of the crosslinking agent used is preferably an amount such that the functional groups possessed by the crosslinking agent account for 30 to 100 mol % relative to 100 mol % of the reactive functional groups possessed by the polymer (reactive functional groups reactive with the crosslinking agent). More preferably, it is 50 to 100 mol %. Using the crosslinking agent in such a ratio allows for the formation of a sufficient crosslinked structure and also reduces the amount of unreacted crosslinking agent remaining in the resulting crosslinked polymer.

[0072] The reaction accelerator used in the method (ii) can be one or more of acids such as sulfuric acid and phosphoric acid; bases such as sodium hydroxide and potassium hydroxide; and condensing agents such as N,N'-dicyclohexylcarbodiimide. The radical generator used in the method (iv) can be the same as the polymerization initiator used in the polymerization step described above. Among the polymerization initiators, peroxides such as hydrogen peroxide, t-butyl hydroperoxide, t-butyl peroxypivalate, octanoyl peroxide, succinic peroxide, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, and t-butylperoxymaleic acid are preferred.

[0073] In the production of the crosslinked polymer of the present invention, when radicals are generated in a polymer and the polymer from which the radicals have been generated is reacted with a crosslinkable monomer to form a crosslinked structure, the amount of crosslinkable monomer used in the post-crosslinking step is preferably 0.1 to 50 mass% relative to 100 mass% of the polymer before the post-crosslinking step. More preferably, it is 1 to 30 mass%. By using the crosslinkable monomer in such a ratio, a sufficient crosslinked structure can be formed, and the amount of unreacted crosslinkable monomer remaining in the obtained crosslinked polymer can also be reduced.

[0074] The production of the crosslinked polymer may include a step of adding an organic acid to the resulting crosslinked polymer after the polymerization reaction. Adding an organic acid to the resulting crosslinked polymer can reduce the amount of residual N-vinyl lactam monomer in the crosslinked polymer. The organic acid is not particularly limited, but examples include organic compounds having an acid group such as a carboxyl group, a sulfonic acid group, a phosphonic acid group, a sulfate group, or a phosphate group. Examples of such organic acids include malonic acid, oxalic acid, succinic acid, aspartic acid, citric acid, glutamic acid, fumaric acid, malic acid, maleic acid, phthalic acid, trimellitic acid, pyromellitic acid, propionic acid, heptanoic acid, octanoic acid, glycolic acid, salicylic acid, lactic acid, L-ascorbic acid, benzoic acid, methanesulfonic acid, benzenesulfonic acid, laurylbenzenesulfonic acid, p-toluenesulfonic acid, benzenephosphonic acid, and lauryl sulfate.

[0075] The amount of the organic acid used is not particularly limited, but is preferably 0.01 to 5% by mass relative to 100% by mass of the N-vinyl lactam monomer charged in the reaction step. When the amount of the organic acid used is within the above range, the amount of the organic acid (salt) can be reduced while reducing the amount of the remaining N-vinyl lactam monomer in the resulting crosslinked polymer. The amount of the organic acid used is more preferably 0.05 to 3% by mass, and even more preferably 0.1 to 1% by mass. The organic acid (salt) refers to the organic acid and the salt of the organic acid, and the salt of the organic acid is primarily a neutralization product of the organic acid and a base added in the neutralization step described below.

[0076] When the organic acid is added to the crosslinked polymer, the reaction time between the organic acid and the crosslinked polymer is not particularly limited, but is preferably 10 minutes to 3 hours, and more preferably 30 minutes to 2 hours.

[0077] The method for producing the crosslinked polymer preferably includes a step of aging the crosslinked polymer after the polymerization reaction. By carrying out the aging step, the amount of residual N-vinyl lactam monomer can be reduced, and the amount of by-products derived from the residual N-vinyl lactam monomer, such as the compound represented by formula (8) described below, can also be reduced. The temperature in the aging step is not particularly limited, but is preferably 60 to 150°C. If the aging temperature is within the above range, the amount of residual N-vinyl lactam monomer can be more sufficiently reduced. It is more preferably 70 to 100°C. The aging time in the aging step is not particularly limited, but is preferably 10 minutes to 5 hours. It is more preferably 30 minutes to 3 hours. When the method for producing the crosslinked polymer includes a step of adding an organic acid, the aging step is preferably carried out before the step of adding the organic acid.

[0078] The aging step may be carried out while disintegrating the crosslinked polymer. When the step of adding an organic acid is included, disintegration allows the organic acid to penetrate more thoroughly into the crosslinked polymer, thereby more sufficiently reducing the amount of residual N-vinyl lactam monomer in the resulting crosslinked polymer. Disintegration of the crosslinked polymer can be carried out by a commonly used method, and examples include methods using a screw extruder such as a kneader or a meat chopper, a gel crusher such as a cutter mill, or the like.

[0079] When an organic acid is added, the method for producing the crosslinked polymer preferably includes a neutralization step after the organic acid addition step. The neutralization method is not particularly limited, but it is preferable to add a base after reacting the organic acid with the crosslinked polymer. The base is not particularly limited, but examples thereof include ammonia; aliphatic amines such as monoethanolamine, diethanolamine, and triethanolamine; aromatic amines such as aniline; and alkali metal hydroxides such as sodium hydroxide and potassium hydroxide. These may be used alone or in combination of two or more. Among these, ammonia, aliphatic amines, and alkali metal hydroxides are preferred, and ammonia, monoethanolamine, diethanolamine, sodium hydroxide, and potassium hydroxide are more preferred.

[0080] The latent heat storage material composition may contain components other than the crosslinked polymer. Examples of the other components include, but are not limited to, water-soluble components (non-crosslinked polymer components that dissolve in water), polymerization initiator residues, residual monomers, polymerization by-products, and moisture, and the composition may contain one or more of these components.

[0081] The latent heat storage material composition can contain, as a by-product during polymerization, a compound represented by the following formula (8):

[0082]

[0083] (In formula (8), R ４ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms which may have a substituent. y represents an integer of 1 to 3. The composition may contain a compound represented by the formula (8), but the proportion of the compound is preferably 2% by mass or less relative to 100% by mass of the N-vinyl lactam crosslinked polymer. When the proportion of the compound represented by the formula (8) is 2% by mass or less, odor and / or coloration of the composition can be sufficiently suppressed. One preferred embodiment of the present invention is an embodiment in which the proportion of the compound represented by the formula (8) is 2% by mass or less relative to 100% by mass of the N-vinyl lactam crosslinked polymer. The proportion of the compound represented by the formula (8) is more preferably 1.5% by mass or less, and even more preferably 1% by mass or less. The proportion of the compound represented by the formula (8) in the composition can be measured by the method described in the Examples. R in the formula (8) ４ and y is R in the above formula (1). ４ and y.

[0084] The proportion of residual monomers such as N-vinyl lactam monomers in the composition is preferably 500 ppm or less relative to 100% by mass of the N-vinyl lactam crosslinked polymer. If the proportion of residual monomers is within the above preferred range, safety will be superior. The proportion of residual monomers is more preferably 300 ppm or less, even more preferably 200 ppm or less, even more preferably 100 ppm or less, and most preferably 50 ppm or less. The proportion of residual monomers in the composition can be measured by the method described in the Examples.

[0085] [Latent Heat Storage Material] The present invention also relates to a latent heat storage material comprising a latent heat storage material composition and a phase transition material. The ratio of the crosslinked polymer to the phase transition material in the latent heat storage material is not particularly limited, but the ratio of the phase transition material to 100% by mass of the crosslinked polymer is preferably 900 to 12,500% by mass, more preferably 1,100 to 10,000% by mass, and even more preferably 1,900 to 5,000% by mass.

[0086] The latent heat storage material may contain other components in addition to the latent heat storage material composition and the phase transition material. Examples of other components include fragrances, antibacterial agents, crystal nucleating agents, colorants, etc. The content of the other components is not particularly limited, but is preferably 0 to 10% by mass relative to 100% by mass of the latent heat storage material. More preferably, it is 0 to 5% by mass, even more preferably 0 to 1% by mass, and most preferably 0% by mass.

[0087] The phase change material is not particularly limited as long as it transitions between a solid phase and a liquid phase in a temperature range of −80 to 80° C., but is preferably an inorganic salt solution and / or at least one selected from the group consisting of alcohols, hydrocarbons, fatty acids, esters, ethers, silicone oils, and fluorocarbons. Preferably, it is an inorganic salt solution or at least one selected from the group consisting of alcohols, hydrocarbons, fatty acids, esters, and ethers.

[0088] The temperature range for the phase transition of the phase transition material is preferably −80 to 70° C., more preferably −75 to 60° C. By combining phase transition materials with different phase transition temperatures, it is possible to maintain a constant temperature at a desired level.

[0089] The inorganic salt used in the phase change material is not particularly limited as long as it can be dissolved in a solvent, but is preferably a metal salt of an alkali metal element such as lithium, sodium, potassium, etc.; an alkaline earth metal element such as calcium, barium, etc.; or a transition metal element such as manganese, iron, cobalt, nickel, copper, zinc, etc. The metal element is preferably a polyvalent metal element, more preferably an alkaline earth metal element, and even more preferably calcium element.

[0090] The metal salt is not particularly limited, but examples thereof include halides, hydroxides, oxides, carbonates, nitrates, sulfates, silicates, phosphonates, carboxylates, etc. Preferred are halides, and more preferred are chlorides.

[0091] The inorganic salt is preferably a polyvalent metal salt, more preferably CaCl ２ , CaBr ２ , CaI ２ , ZnCl ２ and more preferably CaCl ２ The salt concentration in the inorganic salt solution may be adjusted depending on the temperature to be maintained, and is preferably, for example, 1 to 50% by mass, and more preferably 3 to 50% by mass.

[0092] Specific examples of the alcohol include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 1-hexanol, 2-hexanol, 3-hexanol, heptanol, octanol, 2-ethyl-1-hexanol, nonyl alcohol, decyl alcohol, 2-propyl-heptyl alcohol, undecyl alcohol, lauryl alcohol, 2-butyl-octyl alcohol, tridecyl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, and behenyl alcohol. C1 to C30 aliphatic alcohols such as chol; C3 to C30 alicyclic alcohols such as cyclohexanol; C3 to C30 unsaturated alcohols such as (meth)allyl alcohol, 3-buten-1-ol, 3-methyl-3-buten-1-ol, decenol, undecenol, dodecenol, tridecenol, tetradecenol, pentadecenol, hexadecenol, heptadecenol, octadecenol, nonadecenol, eicosenol, heneicosenol, docosenol, palmitoleic alcohol, elaidyl alcohol, oleyl alcohol, and erucyl alcohol.

[0093] The alcohol preferably has 2 to 28 carbon atoms, more preferably 4 to 24 carbon atoms, still more preferably 6 to 20 carbon atoms, and particularly preferably 8 to 18 carbon atoms.

[0094] Preferred examples of the alcohol include aliphatic alcohols such as decyl alcohol, 2-propyl-heptyl alcohol, undecyl alcohol, lauryl alcohol, 2-butyl-octyl alcohol, tridecyl alcohol, and myristyl alcohol; and unsaturated alcohols such as palmitoleic alcohol, elaidyl alcohol, oleyl alcohol, and erucyl alcohol.

[0095] Examples of the hydrocarbon include alkanes having 12 to 30 carbon atoms, such as dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane, icosane, docosane, tetracosane, hexacosane, octacosane, and triacontane.

[0096] The number of carbon atoms in the hydrocarbon is preferably 9 to 25, more preferably 12 to 20. The hydrocarbon is preferably heptadecane (C17), octadecane (C18), nonadecane (C19), icosane (C20), tetradecane (C14), pentadecane (C15), or hexadecane (C16), more preferably octadecane.

[0097] Examples of the fatty acids include saturated fatty acids having 4 to 30 carbon atoms, such as pivalic acid, caproic acid, enanthic acid, caprylic acid, 2-ethylhexanoic acid, pelargonic acid, capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, nonadecylic acid, and arachidic acid; acrylic acid, methacrylic acid, crotonic acid, myristoleic acid, palmitoleic acid, sapienic acid, and oleic acid; monounsaturated fatty acids having 4 to 30 carbon atoms, such as hydroxybenzoic acid, elaidic acid, vaccenic acid, gadoleic acid, eicosenoic acid (paulic acid), erucic acid, and nervonic acid; diunsaturated fatty acids having 4 to 30 carbon atoms, such as linoleic acid, eicosadienoic acid, and docosadienoic acid; and triunsaturated fatty acids having 4 to 30 carbon atoms, such as α-linolenic acid, γ-linolenic acid, pinolenic acid, eleostearic acid, mead acid, dihomo-γ-linolenic acid, and eicosatrienoic acid.

[0098] The number of carbon atoms of the fatty acid is preferably 9 to 25, more preferably 10 to 20. The fatty acid is preferably capric acid, linoleic acid, or oleic acid, more preferably linoleic acid or oleic acid.

[0099] Examples of the esters include fatty acid esters such as methyl laurate, methyl myristate, methyl palmitate, butyl palmitate, methyl stearate, butyl stearate, methyl arachidate, stearyl stearate, and distearyl phthalate.

[0100] Examples of the ether include polyether compounds such as diethylene glycol, triethylene glycol, tetraethylene glycol, triethylene glycol monomethyl ether, polypropylene glycol, polyethylene glycol, polypropylene glycol diacrylate, and ethylethylene glycol.

[0101] The crosslinked polymer of the present invention has a higher liquid absorption capacity for alcohols and fatty acids than the above-mentioned phase change materials. Therefore, by mixing the alcohol and / or fatty acid with a phase change material (e.g., hydrocarbons) that is compatible with these materials, the crosslinked polymer can absorb hydrocarbons and other liquids more effectively. This allows the latent heat storage properties of hydrocarbons and other liquids to be fully exhibited while more fully reducing leakage of the phase change material. In one preferred embodiment of the present invention, the phase change material is a mixture of alcohol and / or fatty acid with at least one selected from the group consisting of hydrocarbons, esters, ethers, silicone oils, and fluorocarbons. More preferably, the phase change material is a mixture of alcohol and / or fatty acid with hydrocarbons, and even more preferably a mixture of alcohol and hydrocarbons.

[0102] The mixing ratio of the alcohol and / or fatty acid to the compatible phase change material is not particularly limited, but the ratio of the compatible phase change material to 100% by mass of the alcohol and / or fatty acid is preferably 1 to 9900% by mass, more preferably 11 to 900% by mass, and even more preferably 25 to 400% by mass.

[0103] The present invention also relates to a method for producing a latent heat storage material, which comprises mixing the latent heat storage material composition of the present invention with a phase change material.The present invention also relates to a method for using the crosslinked polymer having structural units derived from the N-vinyl lactam monomer as an additive for a latent heat storage material, such as a gelling agent for a phase change material.

[0104] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "parts" means "parts by weight" and "%" means "% by mass."

[0105] <Evaluation of Solution (including Solvent) Absorption Capacity of Crosslinked Polymer> Approximately 0.1 g of the crosslinked polymer was accurately weighed (mass W5 (g)), placed in a 4 cm x 5 cm nonwoven fabric tea bag, and sealed by heat sealing. The above procedure was carried out in a room at a temperature of 23±2°C, a relative humidity of 50±5%, and atmospheric pressure. The tea bag was placed in a glass screw tube with a specified volume of 50 mL and immersed in a solution (conductivity of 10 μS / cm or less in the case of deionized water) at room temperature (temperature 23±2°C) and atmospheric pressure for 24 hours. In the case of a solution that solidifies at room temperature, the tea bag was immersed at 50°C for 24 hours. Next, the tea bag was lifted by grasping the end of the tea bag with tweezers, placed one side down on a Kimtowel (manufactured by Nippon Paper Crecia Co., Ltd.), and left to stand for 5 seconds. The tea bag was then placed on the other side down on the Kimtowel and left to stand for 5 seconds to drain the liquid, and the mass (W6 (g)) of the tea bag was measured. Separately, the same procedure was carried out without using the cross-linked polymer, and the mass of the tea bag (W4 (g)) was determined as a blank. The liquid absorption capacity was calculated according to the following formula: Liquid absorption capacity (g / g) = (W6 (g) - W4 (g)) / W5 (g)

[0106] <Measurement of average particle size of crosslinked polymer> The cumulative 50% value measured using a dry particle size distribution measuring device (Model: Mastersizer 3000 dry, manufactured by Spectris, Malvern Division) was taken as the average particle size. The measurement conditions are as follows: (Measurement conditions) Dry laser diffraction scattering method Dispersion pressure: 1 bar Particle refractive index: 1.52 Particle absorption coefficient: 0.01 Particle shape: Aspherical Solvent name: Air (AIR) Measurement range: 0.1 to 3500 μm Coarse particles that could not be measured using a particle size distribution measuring device were measured using a ruler.

[0107] <Quantitative Analysis of Residual Monomer (N-Vinyllactam Monomer) and By-Product (Compound Represented by Formula (8))> Approximately 1 g (mass W7 (g)) of crosslinked polymer and approximately 100 g (mass W8 (g)) of deionized water were accurately weighed into a 110 ml screw tube, and a rotor was placed inside. The tube was then sealed. The above procedure was carried out in a room at a temperature of 23±2°C, a relative humidity of 50±5%, and atmospheric pressure. The mixture was then stirred (600 rpm) using a magnetic stirrer at room temperature (23±2°C) and atmospheric pressure for 16 hours or more. The above procedure extracted the residual N-vinyllactam monomer from the crosslinked polymer and the by-product (compound represented by Formula (8)). The extract was quantitatively analyzed by liquid chromatography under the following conditions. Apparatus: Shiseido "NANOSPACE SI-2" Column: Shiseido "CAPCELLPAK C18 UG120", 20°C Eluent: LC-grade methanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) / ultrapure water = 1 / 24 (mass ratio), with 0.04 mass% added sodium 1-heptanesulfonate Flow rate: 100 μL / min Content (ppm) = measured value (ppm) × (W7 (g) + W8 (g)) / W7 (g)

[0108] <Measurement of Water-Soluble Content> Approximately 1 g of crosslinked polymer (mass W9 (g)) and approximately 100 g of deionized water (mass W10 (g)) were accurately weighed into a 110 ml glass screw tube, a rotor was placed inside, and the tube was sealed. The above procedure was carried out in a room at a temperature of 23±2°C, a relative humidity of 50±5%, and atmospheric pressure. The mixture was then stirred (600 rpm) using a magnetic stirrer at room temperature (23±2°C) and atmospheric pressure for 16 hours or more, and then filtered through qualitative filter paper (Advantec Co., Ltd., Model: No. 2) to obtain a soluble component extract. Approximately 10 g of the extract (mass W12 (g)) was then weighed into an aluminum cup (mass W11 (g)) with a bottom diameter of approximately 5 cm, and the cup was left to dry in a constant temperature dryer at 120°C for 2 hours. The mass (W13 (g)) of the aluminum cup + soluble components after drying was measured, and the soluble content was calculated using the following formula: Soluble content (mass%) = ((W13 (g) - W11 (g)) / (W12 (g) × W9 (g) / W10 (g))) × 100

[0109] <Production Example 1> 3150.0 parts of N-vinylpyrrolidone (manufactured by Nippon Shokubai Co., Ltd., hereinafter also referred to as VP), 12.6 parts (0.18 mol% relative to VP) of triallyl cyanurate (triallyl cyanurate) (hereinafter also referred to as CTA) as a crosslinkable monomer, and 6720.5 parts of deionized water were charged into a kneader (manufactured by Koike Iron Works Co., Ltd., LDS-100 model) with a main tank made of stainless steel (SUS304). Next, nitrogen substitution was performed at 2 L / min for 30 minutes. Next, nitrogen introduction was increased to 0.8 L / min, the temperature was raised to 48 ° C, and stirring was initiated by rotating the kneader blades. After stabilizing the liquid temperature at 48°C, 126.5 parts (0.67 g per mole of the total amount of VP and CTA used) of a 15% by mass aqueous solution of 2,2'-azobis(2-methylpropionamidine) dihydrochloride (hereinafter also referred to as "V-50") was added as an initiator to initiate polymerization. After the polymerization reaction progressed and a gel was formed, the mixture was aged at 90°C for 60 minutes while the kneader blades were rotated to break up the gel, and the polymerization was terminated. The resulting gel was then dried at 125°C for 5 hours to obtain a dried VP crosslinked polymer. The resulting crosslinked polymer was then pulverized in a pulverizer until it passed through a 710 μm sieve, yielding a particulate VP crosslinked polymer (1). The physical properties of the resulting VP crosslinked polymer (1) were evaluated using the methods described above. The results are shown in Table 1.

[0110] <Production Example 2> 1000.0 parts of VP, 15.0 parts (0.65 mol % relative to VP) of pentaerythritol triallyl ether (manufactured by Daiso Co., Ltd., trade name: Neoallyl P-30M, used after adjusting the pH to 6 or higher with diethanolamine) as a crosslinkable monomer, and 2368.33 parts of deionized water were charged into a benchtop kneader (manufactured by Chuorika Co., Ltd., PNV-5H model). Subsequently, nitrogen substitution was carried out at 400 ml / min for 40 minutes. Subsequently, nitrogen introduction was increased to 30 ml / min, and the temperature was raised to 56°C. After the liquid temperature was stabilized at 56°C, 47.37 parts of a 15% by mass aqueous solution of V-50 as an initiator (0.78 g per 1 mol of the total amount of VP and pentaerythritol triallyl ether used) was added to initiate polymerization. After the polymerization reaction progressed and a gel was formed, the mixture was aged at 90°C for 60 minutes while the kneader blades were rotated to break up the gel, and the polymerization was terminated. Next, 500.0 parts of a 1.4% by mass aqueous solution of malonic acid was added over 3 minutes and stirred at 90 ° C. for 60 minutes. Furthermore, 250.0 parts of a 2.8% by mass aqueous solution of diethanolamine was added over 3 minutes and stirred for 30 minutes. Next, the resulting gel was dried at 120 ° C. for 3 hours (Yamato Scientific Co., Ltd. Precision Incubator Model DF42, maximum opening, outer size 232 x 297 x 50H (mm) stainless steel tray, outer size 8 x 267 x 40H (mm) stainless steel tray) to obtain a dried VP crosslinked polymer. Next, the obtained crosslinked polymer was pulverized in a pulverizer and further pulverized in a jet mill to obtain VP crosslinked polymer (2). The physical properties of the obtained VP crosslinked polymer (2) were evaluated using the method described above. The results are shown in Table 1.

[0111] <Production Example 3> 50.0 parts of VP, 1.0 part of CTA as a crosslinkable monomer (0.9 mol% relative to VP), and 119.0 parts of deionized water were charged into a 250 ml polypropylene container. Stirring was then initiated with a magnetic stirrer, and nitrogen substitution was performed at 100 ml / min for 30 minutes. Nitrogen introduction was then increased to 30 ml / min, and the temperature was raised to 40°C while continuing stirring. After the liquid temperature was stabilized at 40°C, 1.1 parts (0.25 g per mole of the total amount of VP and CTA used) of a 10% by mass aqueous solution of 2,2'-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride (hereinafter also referred to as "VA-044") was added as an initiator, and polymerization was initiated. After the polymerization reaction progressed and a gel was formed, the mixture was aged at 90°C for 30 minutes, and the polymerization was then terminated. The resulting gel was crushed in a 1 L kneader and dried at 120°C for 2 hours to obtain a dried VP crosslinked polymer. The resulting crosslinked polymer was then crushed in a crusher to obtain a particulate VP crosslinked polymer (3). The physical properties of the resulting VP crosslinked polymer (3) were evaluated by the methods described above. The results are shown in Table 1.

[0112] <Production Example 4> 8.4 parts of VP, 0.03 parts of CTA as a crosslinkable monomer (0.2 mol% relative to VP), 0.015 parts of VA-044 as an initiator (0.2 g relative to 1 mol of the total amount of VP and CTA used), and 12.6 parts of deionized water were charged into a 50 ml screw bottle. Next, while stirring with a magnetic stirrer, nitrogen substitution was performed for 30 minutes at 100 ml / min. Next, the solution in the screw bottle after nitrogen substitution was transferred to a 10 cm diameter Petri dish and irradiated with UV for 8 minutes using a UV irradiation device (Ushio Inc., lamp power supply: HB-25103BY-C, cumulative light intensity (1 minute): 1310 mJ / cm2). After the polymerization reaction progressed, the resulting crosslinked polymer was cut with scissors into approximately 5 mm x 5 mm pieces and vacuum dried at 100°C for 3 hours to obtain a cubic VP crosslinked polymer (4). The physical properties of the obtained VP crosslinked polymer (4) were evaluated by the methods described above. The results are shown in Table 1. For the evaluation of the N-vinylpyrrolidone content, the by-product (2-pyrrolidone) content, and the water-soluble content, the VP comparative crosslinked polymer (4) was classified using JIS standard sieves with openings of 250 μm and 500 μm, and the VP comparative crosslinked polymer (4) with openings of 250 to 500 μm was used.

[0113] <Production Example 5> 50 g of a 37% by mass aqueous solution of sodium acrylate (manufactured by Nippon Shokubai Co., Ltd.), 0.02 g of polyethylene glycol diacrylate (NK Ester A-400, manufactured by Shin-Nakamura Chemical Co., Ltd., EO addition mole number 9 moles, hereinafter also referred to as "A-400") as a crosslinkable monomer, and 42 g of deionized water were charged into a 250 ml PP container. Next, stirring was started with a magnetic stirrer, and nitrogen substitution was carried out at 100 ml / min for 30 minutes. Next, the temperature was raised to 40°C while continuing stirring. After the liquid temperature was stabilized at 40°C, 0.8 g of a 10% by mass aqueous solution of V-50 was added as an initiator to initiate polymerization. After the polymerization reaction progressed and a gel was formed, the mixture was aged at 90°C for 30 minutes to terminate the polymerization. The resulting gel was crushed using a bench kneader (PNV-1H model manufactured by Chuorika Co., Ltd.) and dried at 120°C for 2 hours to obtain a dried sodium acrylate cross-linked polymer (AA-Na cross-linked polymer). The resulting cross-linked polymer was then crushed using a crusher to obtain a particulate AA-Na cross-linked polymer. The physical properties of the resulting AA-Na cross-linked polymer were evaluated using the methods described above. The results are shown in Table 1.

[0114] <Production Example 6> 27 g of methoxypolyethylene glycol acrylate (NK Ester AM-90G manufactured by Shin-Nakamura Chemical Co., Ltd., EO addition mole number 9 moles, hereinafter also referred to as "PEG"), 3 g of 2-hydroxyethyl acrylate (manufactured by Nippon Shokubai Co., Ltd.) (hereinafter also referred to as HEA) containing 0.2 mass% of ethylene glycol diacrylate as an impurity, and 70 g of deionized water were charged into a 250 ml PP container. Next, stirring was started with a magnetic stirrer, and nitrogen substitution was carried out at 100 ml / min for 30 minutes. Next, the temperature was raised to 40°C while continuing stirring. After the liquid temperature was stabilized at 40°C, 0.1 g of a 20 mass% aqueous solution of V-50 was added as an initiator to initiate polymerization. After the polymerization reaction progressed and a gel was formed, the mixture was aged at 90°C for 30 minutes to terminate the polymerization. The resulting gel was crushed using a benchtop kneader (PNV-1H model, manufactured by Chuo Rika Co., Ltd.) and dried at 120°C for 2 hours (using a precision incubator, Model DF42, manufactured by Yamato Scientific Co., Ltd., with maximum opening and one stainless steel tray with outer dimensions of 206 x 267 x 40H (mm)). This gave a PEG acrylate / HEA crosslinked polymer (PEG / HEA crosslinked polymer). The physical properties of the resulting PEG / HEA crosslinked polymer were evaluated using the methods described above. The results are shown in Table 1. Note that for "polyvinylpyrrolidone" in Table 1, K-85 manufactured by Nippon Shokubai Co., Ltd. was used.

[0115]

[0116] Examples 1 to 4, Comparative Examples 1 to 3 The liquid absorption capacities of lauryl alcohol, octadecane, and a mixed solution of lauryl alcohol / octadecane (60 / 40 mol%) obtained in Production Examples 1 to 6 were measured for the VP crosslinked polymer, AA-Na crosslinked polymer, PEG / HEA crosslinked polymer, and polyvinylpyrrolidone. All were immersed at 50°C. For lauryl alcohol, the amount of liquid absorbed after immersion for 1 hour was also measured. In addition, 5% polymer (Production Examples 1 to 6, polyvinylpyrrolidone) was added to a mixed solution of lauryl alcohol and lauryl alcohol / octadecane (60 / 40 mol%), and the fluidity of the liquid + polymer was confirmed after standing at 50°C for 24 hours. The fluidity was confirmed by weighing the solution into a screw tube and tilting it. The results are shown in Table 2.

[0117]

[0118] Examples 5 to 8, Comparative Examples 4 to 6 The liquid absorption capacity of saturated calcium chloride aqueous solution (approximately 50%) was measured for the VP crosslinked polymer, AA-Na crosslinked polymer, PEG / HEA crosslinked polymer, and polyvinylpyrrolidone obtained in Production Examples 1 to 6. Similar evaluations were performed at immersion temperatures of 5°C as well as room temperature. At room temperature, the amount of liquid absorbed after immersion for 1 hour was also measured. Furthermore, 5% of the polymer (Production Examples 1 to 6, polyvinylpyrrolidone) was added to the saturated calcium chloride aqueous solution, and the fluidity of the liquid + polymer was confirmed after leaving it at room temperature (23±2°C) and normal pressure for 24 hours. The fluidity was confirmed by weighing it into a screw tube and tilting it. The results are shown in Table 3.

[0119]

[0120] Examples 9 to 14 The liquid absorption capacity of the VP crosslinked polymer (1) obtained in Production Example 1 was measured for solutions in which the mixing ratio of lauryl alcohol / octadecane was changed. All samples were immersed at 50°C. The results are shown in Table 4.

[0121]

[0122] Example 15 The liquid absorption capacity of the VP crosslinked polymer (1) obtained in Production Example 1 was measured in a solution in which the lauryl alcohol was replaced with a longer-chain oleyl alcohol or a fatty acid. The sample was immersed at 50°C. The results are shown in Table 5. It was confirmed that the liquid absorption capacity tends to decrease as the carbon number increases and the hydrophobicity increases. It was also confirmed that, with the same number of carbon atoms, fatty acids tend to have a higher liquid absorption capacity than higher alcohols.

[0123]

[0124] Example 16 5% of the VP crosslinked polymer (1) obtained in Production Example 1 was added to each of solutions of lauryl alcohol, oleyl alcohol, and oleic acid, and the fluidity of the solution + VP crosslinked polymer (1) was confirmed after standing at 50°C for 24 hours. The fluidity was confirmed by weighing the solution into a screw tube and tilting it. The solution was then solidified in a refrigerator / freezer, and the fluidity of the solution + VP crosslinked polymer (1) was confirmed when it was liquefied again at 50°C. (First cycle) The same cycle was then repeated five times, and the fluidity of the solution + VP crosslinked polymer (1) was confirmed. The results are shown in Table 6. Five cycles were repeated, but no change was observed, and the VP crosslinked polymer (1) retained its liquid state and remained in a gel state.

[0125]

Claims

1. A latent heat storage material composition comprising a crosslinked polymer having structural units derived from an N-vinyl lactam monomer.

2. The latent heat storage material composition according to claim 1, wherein the crosslinked polymer has a structure derived from a crosslinking agent, and the crosslinking agent is a compound having two or more ethylenically unsaturated bonds.

3. The latent heat storage material composition according to claim 1 or 2, wherein the crosslinked polymer has a structure derived from a crosslinking agent, and the crosslinking agent comprises at least one selected from the group consisting of a crosslinkable monomer having a cyanuric acid skeleton, pentaerythritol (di-, tri-, tetra-)(meth)allyl ether, triallyl isocyanurate, triallyl phosphate, triallylamine, diallyl carbonate, 1,3-bis(allyloxy)-2-propanol, divinylethylene urea, 1,4-butylene bis(N-vinylamide), and (di-, tri-, tetra-, penta-, hexa-, hepta-, octa-)allylsucrose.

4. The latent heat storage material composition according to claim 2 or 3, wherein the proportion of the structure derived from the crosslinking agent is 0.01 to 2 mol % relative to 100 mol % of all structural units.

5. The latent heat storage material composition according to any one of claims 1 to 4, wherein the crosslinked polymer has an average particle size of 10 to 1000 μm.

6. A latent heat storage material comprising the latent heat storage material composition according to any one of claims 1 to 5 and a phase change material.

7. The latent heat storage material according to claim 6, wherein the phase change material is an inorganic salt solution and / or at least one selected from the group consisting of alcohols, hydrocarbons, fatty acids, esters, ethers, silicone oils and fluorocarbons.

Images