WO2021131404A1 - Microcapsule, heat storage composition, heat storage sheet, and method for producing microcapsule - Google Patents

Abstract

The present invention addresses the problem of providing a microcapsule having a high heat storage amount per unit volume. In addition, the present invention also addresses the problem of providing a heat storage composition, a heat storage sheet, and a method for producing a microcapsule.　The microcapsule of the present invention contains a polyhydric alcohol as a main component.

Description

Manufacturing method of microcapsules, heat storage composition, heat storage sheet, microcapsules

The present invention relates to a method for producing microcapsules, a heat storage composition, a heat storage sheet, and microcapsules.

In recent years, microcapsules have the potential to provide new value to customers in terms of including and protecting functional materials such as fragrances, dyes, heat storage materials, adhesive curing agents, and pharmaceutical ingredients. It is attracting attention because there is.

For example, microcapsules containing paraffins as a phase change substance (PCM: Phase Change Material) are known. For example, Patent Document 1 discloses an invention relating to a heat storage microcapsule in which a capsule wall containing polyorganosiloxane as a main component is formed around a core substance containing a phase-transferable compound as a main component. ..

Japanese Unexamined Patent Publication No. 2002-003828

Regarding heat storage microcapsules containing a heat storage material such as PCM (for example, the microcapsules described in Patent Document 1), the amount of heat storage per unit volume is higher from the viewpoint of developing a high amount of heat storage in a limited space. High microcapsules are required.

In view of the above, it is an object of the present invention to provide microcapsules that are superior in the amount of heat storage per unit volume. Another object of the present invention is to provide a method for producing a heat storage composition, a heat storage sheet, and microcapsules.

As a result of diligent studies on the above problems, the present inventor has found that the above problems can be solved by the following configuration.

[1]
Microcapsules containing polyhydric alcohol as the main component.
[2]
The microcapsules according to [1], wherein the content of the polyhydric alcohol is 60% by mass or more with respect to the total mass of the microcapsules.
[3]
The microcapsules according to [1] or [2], wherein the polyhydric alcohol has a molecular weight of 100 to 500.
[4]
The microcapsule according to any one of [1] to [3], wherein the polyhydric alcohol contains a diol compound.
[5]
The microcapsule according to any one of [1] to [4], wherein the polyhydric alcohol contains a compound represented by the formula (1) described later.
[6]
The microcapsule according to any one of [1] to [5], wherein the polyhydric alcohol contains a compound represented by the formula (2) described later.
[7]
The microcapsule according to [6], wherein n is an even number of 8 or more.
[8]
The microcapsule according to any one of [1] to [7], wherein the polyhydric alcohol has a melting point of 90 ° C. or lower.
[9]
The microcapsule according to any one of [1] to [8], wherein the capsule wall contains at least one selected from the group consisting of polyurea and polyurethane urea.
[10]
The microcapsule according to any one of [1] to [8], wherein the capsule wall contains an acrylic resin.
[11]
The microcapsule according to any one of [1] to [10], wherein the median diameter based on the volume of the microcapsule is 100 μm or less.
[12]
A heat storage composition containing a polyhydric alcohol having a molecular weight of 100 to 500 as a main component.
[13]
The heat storage composition according to [12], wherein the polyhydric alcohol contains a diol compound.
[14]
The heat storage composition according to [13], wherein the polyhydric alcohol contains a compound represented by the formula (1) described later.
[15]
The heat storage composition according to [13] or [14], wherein the polyhydric alcohol contains a compound represented by the formula (2) described later.
[16]
The heat storage composition according to [15], wherein n is an even number of 8 or more.
[17]
The heat storage composition according to any one of [12] to [16], wherein the polyhydric alcohol has a melting point of 90 ° C. or lower.
[18]
A heat storage sheet containing the microcapsules according to any one of [1] to [11] or the heat storage composition according to any one of [12] to [17].
[19]
The method for producing microcapsules according to any one of [1] to [11], wherein the polyhydric alcohol, the capsule wall forming material, and the SP value are 20 (cal / cm ³ ) ^1/2 or less. A microcapsule containing a step of preparing an emulsion containing a solvent and a step of reacting the capsule wall-forming material to form a capsule wall and forming the microcapsule containing the polyhydric alcohol. Production method.
[20]
The production method according to [19], wherein the capsule wall forming material contains a polyisocyanate and a polyamine.
[21]
The method for producing microcapsules according to any one of [1] to [11], wherein the polyhydric alcohol and ^{a monomer having an SP value of 20 (cal / cm 3} ) ^1/2 or less are mixed. The step of preparing the first emulsion, the step of mixing the first emulsion and water to prepare the second emulsion, and the step of polymerizing the monomer in the second emulsion. A method for producing microcapsules, which comprises a step of forming a capsule wall and forming the microcapsules containing the polyhydric alcohol.
[22]
The method for producing microcapsules according to any one of [1] to [11], the step of mixing the polyvalent alcohol and the capsule wall forming material to prepare a mixed solution, and the mixed solution. And water to prepare an emulsion, and a step of reacting the capsule wall-forming material in the emulsion to form a capsule wall and forming the microcapsules containing the polyhydric alcohol. And, including, a method of manufacturing microcapsules.

According to the present invention, it is possible to provide microcapsules that are superior in the amount of heat storage per unit volume. In addition, a method for producing a heat storage composition, a heat storage sheet, and microcapsules can be provided.

Hereinafter, the present invention will be described in detail.
The numerical range represented by using "-" in the present specification means a range including the numerical values before and after "-" as the lower limit value and the upper limit value.
Further, in the numerical range described stepwise in the present specification, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the upper limit value or the lower limit value of another numerical range described stepwise. Good. Further, in the numerical range described in the present specification, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the value shown in the examples.
Various components described later may be used alone or in combination of two or more. For example, the polyhydric alcohol described later may be used alone or in combination of two or more.
In the present specification, (meth) acrylate represents acrylate and methacrylate, and (meth) acrylic represents acrylic and methacryl.
In the present specification, "preparation" means not only the act of synthesizing and / or blending to prepare a specific material, but also the act of procuring a predetermined item such as purchase.
In the present specification, "room temperature" means 25 ° C. unless otherwise specified.
When referring to a value that may fluctuate with temperature in the present specification, the value is a value at 25 ° C. unless otherwise specified.

In the present specification, the “SP value” means the “value of the solubility parameter” (unit: (cal / cm ³ ) ^1/2 ). The SP value referred to in the present specification is the Hansen solubility parameter according to the formula explained in Hansen Solubility Parameter: A User's Handbook, Second Edition, CMHansen (2007), Taylor and Francis Group, LLC (HSPiP Manual). Using the Hansen solubility parameter HSPiP 3rd edition (software version 5.1.08), the SP value calculated by the following formula is used.
(SP value) ² = (δHd) ² + (δHp) ² + (δHh) ² (Hd: dispersion contribution, Hp: polarity contribution, Hh: hydrogen bond contribution)

[Microcapsules]
The microcapsules of the present invention contain a polyhydric alcohol as a main component.
As used herein, the term "included as a main component" means that the component has the highest content among the components contained as a core material in microcapsules.
When the microcapsules contain two or more kinds of polyhydric alcohols, "containing the polyhydric alcohol as a main component" means that the total content of the two or more kinds of polyhydric alcohols is included in the microcapsules. It means that it is higher than other components other than polyhydric alcohol.

The polyhydric alcohol contained in the microcapsules of the present invention as a main component has a high heat storage amount per unit mass and has two or more hydroxy groups in the molecule, so that hydrogen bonds between the molecules are appropriately formed. , Has a high density. Therefore, it is considered that microcapsules containing polyhydric alcohol and polyhydric alcohol as main components have a high heat storage amount per unit volume.
Hereinafter, the fact that the amount of heat stored per unit volume of the microcapsules is more excellent is also described as “the effect of the present invention is more excellent”.

The microcapsule has a core portion and a wall portion for encapsulating a core material (encapsulated (also referred to as an encapsulating component)) forming the core portion. In the present specification, the wall portion is also referred to as a "capsule wall".

[Core material]
Microcapsules contain polyhydric alcohol as a core material (inclusion component). Since the polyhydric alcohol is encapsulated in microcapsules, it can stably exist in a phase state depending on the temperature.

<Multivalent alcohol>
The polyhydric alcohol contained in the microcapsules is not particularly limited as long as it is an alcohol having at least two hydroxy groups.
The polyhydric alcohol preferably contains a chain or cyclic aliphatic hydrocarbon group and has a structure in which at least two hydroxy groups are substituted in the main chain skeleton which may have a substituent. The main chain skeleton includes, for example, a chain or cyclic aliphatic hydrocarbon group and a group formed by substituting one or more carbon atoms constituting the chain or cyclic aliphatic hydrocarbon group with a heteroatom. Can be mentioned.

The polyhydric alcohol is preferably a linear polyhydric alcohol because it is more excellent in the effect of the present invention. A linear polyhydric alcohol is a group formed by substituting one or more carbon atoms constituting a linear aliphatic hydrocarbon group or a linear aliphatic hydrocarbon group with a heteroatom. It means having a chain skeleton. Since the linear polyhydric alcohol is densely packed when in the solid state, the entropy change between the dense solid state and the melted liquid state is larger, and the latent heat of the compound is further improved. It is presumed to do.
Further, it is preferable that the main chain skeleton of the polyhydric alcohol does not have a substituent because it is more excellent in the effect of the present invention.

When the main chain skeleton of the polyhydric alcohol is an aliphatic hydrocarbon group, the number of carbon atoms thereof is preferably 6 or more and more preferably 8 or more in that the latent heat of the compound is higher. The upper limit is not particularly limited, but 16 or less is preferable, and 14 or less is more preferable, in that the melting point falls within a preferable range described later and the density becomes higher. When the main chain skeleton is a group in which one or more carbon atoms constituting an aliphatic hydrocarbon group are substituted with heteroatoms, the total number of carbon atoms and heteroatoms is preferably included in the above range. ..
Examples of the heteroatom when the main clavicle of the polyhydric alcohol has a heteroatom include -O-, -S- and -NH-, and -O- or -S- is preferable.

The number of hydroxy groups contained in the polyhydric alcohol is not particularly limited, but 2 to 4 is preferable, and 2 or 3 is more preferable. In particular, the polyhydric alcohol is preferably a diol compound having two hydroxy groups because it is more excellent in the effect of the present invention. When the polyhydric alcohol is a diol compound, it is presumed that hydrogen bonds between the molecules are appropriately formed and the density in the core portion is improved.

Examples of the diol compound include a compound represented by the following formula (1).
HO-R ^1- OH (1)
In the formula, R ¹ is an aliphatic hydrocarbon group having 8 or more carbon atoms or a group in which one or more carbon atoms constituting the aliphatic hydrocarbon group having 8 or more carbon atoms are substituted with heteroatoms. Represents a divalent linking group. However, the two groups selected from the hydroxy group and the hetero atom in the formula (1) do not bond with each other. For example, if the heteroatom is an oxygen atom, it does not combine with a hydroxy group or other heteroatom to form a group such as —O—OH or —O—O—.

In the formula (1), as ^{the aliphatic hydrocarbon group in R 1} , a linear alkylene group having 8 to 16 carbon atoms is preferable, and a linear alkylene group having 8 to 12 carbon atoms is more preferable. Further, it is preferable that the aliphatic hydrocarbon group has an even number of carbon atoms in that the effect of the present invention is more excellent.
When R ¹ is a divalent linking group having the above heteroatom, the total number of carbon atoms and heteroatoms is preferably the above number.
Further, ^{examples of the heteroatom when R 1} is a divalent linking group having the above heteroatom include -O-, -S- and -NH-, and from the viewpoint of proper capsule wall formation,- O- or -S- is preferable, -S- is more preferable, and -O- or -NH- is preferable from the viewpoint of heat storage amount.

As the diol compound, a compound represented by the following formula (2) is preferable.
HO- (R ² ) _n- OH (2)
In the formula, R ² independently represents a methylene group, —O— or —S—. n represents an integer of 8 or more. However, the two groups selected from the hydroxy group, —O— and —S— in formula (2) do not bond to each other. That is, for example, it does not form a group such as —O—S—, —O—OH, —S—OH.

In the formula (2), R ² is preferably a methylene group or —S— independently, and more preferably a methylene group.
n is preferably an integer of 8 to 16, more preferably an integer of 8 to 12.
Further, in that the effect of the present invention is more excellent, n is preferably an even number of 8 or more, more preferably an even number of 8 to 16, and further preferably an even number of 8 to 12.

Examples of the diol compound include 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,14-tetradecanediol, and 1, , 2-Decandiol, 3,6-dithia-1,8-octanediol, 3,6-diazaoctane-1,8-diol, iminodiethanol, N, N-bis (2-hydroxyethyl) ethylenediamine, 1,4 Examples thereof include -bis (2-hydroxyethyl) piperazine and N, N-bis (2-hydroxyethyl) -1,8-octanediamine.
Examples of the trifunctional or higher functional polyhydric alcohol include 1,2,6-hexanetriol, 1,2,8-octanetriol, 1,2,10-decantriol, and 1,8 bis (2,). 3-Dihydroxypropyloxy) octane can be mentioned.
Polyhydric alcohols include 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol or 3,6-dithia-1,8. -Octanediol is preferred, 1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol or 3,6-dithia-1,8-octanediol is more preferred, 1,8-octanediol or 1,10-decanediol is more preferred.

The molecular weight of the polyhydric alcohol is not particularly limited, but 100 to 500 is preferable, and 100 to 300 is more preferable, because the heat storage amount and the density per molecule are excellent in a well-balanced manner.

The melting point of the polyhydric alcohol is close to the operating temperature of an electronic device (particularly, a small or portable electronic device), and is preferably 90 ° C. or lower, more preferably 80 ° C. or lower, in terms of excellent applicability to the electronic device. 70 ° C. or lower is more preferable. The lower limit is not particularly limited, but is preferably 0 ° C. or higher, more preferably 10 ° C. or higher, and even more preferably 15 ° C. or higher.

The polyhydric alcohol may be used alone or in combination of two or more. When a plurality of multivalent alcohols having different melting points are used, the temperature range in which the heat storage property is exhibited can be widened.
When applying microcapsules to electronic devices, it is also preferred that there is substantially one type of polyhydric alcohol. When there is substantially one type, the polyhydric alcohol is encapsulated in microcapsules with high purity, so that the endothermic property is good. Here, the fact that the polyhydric alcohol is substantially one type means that the content of the main polyhydric alcohol is 95 to 100% by mass with respect to the total mass of the polyhydric alcohol, and is 98 to 100. It is preferably mass%.
The "main polyhydric alcohol" refers to the polyhydric alcohol having the highest content among the plurality of polyhydric alcohols contained in the microcapsules.

The content of the polyhydric alcohol in the core material is not particularly limited, but is preferably 80% by mass or more, more preferably 90% by mass or more, and more preferably 95% by mass or more, based on the total mass of the core material in that the heat storage property is more excellent. Mass% or more is more preferable, and 98% by mass or more is particularly preferable. The upper limit is 100% by mass.

The content of the polyhydric alcohol in the microcapsules is not particularly limited, but is preferably 50% by mass or more, more preferably 60% by mass or more, more preferably 75% by mass or more, based on the total mass of the microcapsules, in that the heat storage property is more excellent. It is more preferably mass% or more, and particularly preferably 85% by mass or more. The upper limit of the content of the polyhydric alcohol is not particularly limited, but is preferably 99.9% by mass or less, more preferably 99% by mass or less, and 97% by mass, based on the total mass of the microcapsules in terms of being superior in strength. % Or less is more preferable.

(density)
The density of the polyhydric alcohol is not particularly limited, but 0.85 g / cm ³ or more is preferable, 0.9 g / cm ³ or more is more preferable, and 1.0 g / cm is preferable in that the heat storage property per unit volume can be further increased. ³ or more is more preferable. The upper limit is not particularly limited, but in many cases it is ^{2.0 g / cm 3 or less.}

(Latent heat capacity)
The latent heat capacity of the polyhydric alcohol is preferably high, preferably 200 J / cm ³ or more, more preferably 210 J / cm ³ or more, and even more preferably 250 J / cm ³ or more. The upper limit is not particularly limited, but in many cases it is ^{350 J / cm 3 or less.}
The latent heat capacity is the amount of heat stored per unit mass (J / g) of polyvalent alcohol measured by differential scanning calorimetry (DSC) and the density of polyvalent alcohol measured by a densitometer (g / g). It is a value calculated from cm ^3).

<Second heat storage material>
The microcapsules may contain a second heat storage material as a core material (inclusion component). In this specification, the second heat storage material does not contain the above-mentioned polyhydric alcohol.
The type of the second heat storage material is not particularly limited as long as it is a heat storage material other than the polyhydric alcohol. As the second heat storage material, a material whose phase changes according to the temperature change can be used, and the phase change between the solid phase and the liquid phase accompanied by the state change of melting and solidification according to the temperature change can be repeated. A material that can be produced is preferable.
The phase change of the second heat storage material is preferably based on the phase change temperature of the second heat storage material itself, and in the case of the phase change between the solid phase and the liquid phase, it is preferably based on the melting point.

As the second heat storage material, for example, a material capable of storing heat generated outside the microcapsule as sensible heat, and a material capable of storing heat generated outside the microcapsule as latent heat (hereinafter, also referred to as "latent heat storage material"). ), And a material that causes a phase change due to a reversible chemical change. The second heat storage material is preferably one that can release the stored heat.
Among them, the latent heat storage material is preferable as the second heat storage material in terms of the ease of controlling the amount of heat that can be transferred and the amount of heat that can be transferred.

The latent heat storage material is a material that stores heat generated outside the microcapsules as latent heat. For example, in the case of a phase change between a solid phase and a liquid phase, it refers to a material capable of transferring heat by latent heat by repeating the change between melting and solidification with the melting point determined by the material as the phase change temperature.
In the case of a phase change between a solid phase and a liquid phase, the latent heat storage material can store heat and dissipate heat with a phase change between a solid and a liquid by utilizing the heat of fusion at the melting point and the heat of solidification at the freezing point.

The type of latent heat storage material is not particularly limited, and can be selected from compounds having a melting point and capable of phase change.
Examples of the latent heat storage material include ice (water); inorganic salts; aliphatic hydrocarbons such as paraffin (for example, isoparaffin and normal paraffin); tri (capryl capric acid) glyceryl, methyl myristate (melting point 16-19 ° C.). ), Fatty acid ester compounds such as isopropyl myristate (melting point 167 ° C.) and dibutyl phthalate (melting point -35 ° C.); alkylnaphthalene compounds such as diisopropylnaphthalene (melting point 67-70 ° C.), 1-phenyl-1. -Diarylalkane compounds such as xylylethane (melting point less than -50 ° C), alkylbiphenyl compounds such as 4-isopropylbiphenyl (melting point 11 ° C), triarylmethane compounds, alkylbenzene compounds, benzylnaphthalene compounds, diarylalkylene compounds Compounds and aromatic hydrocarbons such as arylindane compounds; natural animal and vegetable oils such as camellia oil, soybean oil, corn oil, cottonseed oil, rapeseed oil, olive oil, palm oil, paraffin oil, and fish oil; mineral oil; and diethyl. Examples include ethers.

The phase change temperature of the second heat storage material is not particularly limited, and may be appropriately selected depending on the type of heating element that generates heat, the heating temperature of the heating element, the temperature or holding temperature after cooling, and the cooling method.
As the second heat storage material, a material having a phase change temperature (preferably melting point) in a target temperature range (for example, operating temperature of a heating element; hereinafter, also referred to as “heat control range”) may be selected. preferable.
The phase change temperature of the second heat storage material varies depending on the heat control region, but is preferably 0 to 80 ° C, more preferably 10 to 70 ° C.

Among them, aliphatic hydrocarbons are preferable, paraffin is more preferable, and linear paraffin is further preferable as the latent heat storage material because the effect of the present invention is more excellent.

Examples of the linear paraffin include n-tetradecane (melting point 6 ° C.), n-pentadecane (melting point 10 ° C.), n-hexadecan (melting point 18 ° C.), n-heptadecane (melting point 22 ° C.), and n-octadecan (melting point 22 ° C.). Melting point 28 ° C), n-nonadecan (melting point 32 ° C), n-eicosan (melting point 37 ° C), n-henikosan (melting point 40 ° C), n-docosan (melting point 44 ° C), n-tricosan (melting point 48-50 ° C) ), N-Tetracosan (melting point 52 ° C), n-pentacosan (melting point 53-56 ° C), n-hexakosan (melting point 57 ° C), n-heptacosan (melting point 60 ° C), n-octakosan (melting point 62 ° C), n -Nonacosan (melting point 63-66 ° C.) and n-triacontane (melting point 66 ° C.) can be mentioned.

As the inorganic salt, an inorganic hydrate is preferable, and for example, an alkali metal chloride hydrate (eg, sodium chloride dihydrate, etc.) and an alkali metal acetate hydrate (eg, sodium acetate water). Japanese products, etc.), alkali metal sulfate hydrates (eg, sodium sulfate hydrate, etc.), alkali metal thiosulfate hydrates (eg, sodium thiosulfate hydrate, etc.), alkaline earth metals Examples thereof include sulfate hydrates (eg, calcium sulfate hydrate, etc.) and alkaline earth metal chloride hydrates (eg, calcium chloride hydrate, etc.).

When the microcapsule contains the second heat storage material, the second heat storage material may be used alone or in combination of two or more. By using a second heat storage material having a melting point different from that of the polyhydric alcohol, the temperature range in which the heat storage property is exhibited and the amount of heat storage can be adjusted according to the application.

The content of the second heat storage material in the core material is not particularly limited, but is preferably less than 30% by mass, more preferably less than 10% by mass, still more preferably 1% by mass or less, based on the total mass of the core material. The lower limit is not particularly limited, but 0% by mass can be mentioned.
The total content of the polyhydric alcohol and the second heat storage material in the core material is not particularly limited, but is preferably 80 to 100% by mass, preferably 90 to 100% by mass, based on the total mass of the core material in terms of better heat storage. 100% by mass is more preferable.

<Other ingredients>
The core material of the microcapsules may contain components other than the above-mentioned heat storage material. Other components that can be included in the microcapsules as the core material include, for example, solvents and additives such as flame retardants.

The microcapsules may contain a solvent as a core material.
Examples of the solvent in this case include a heat storage material whose melting point deviates from the temperature range in which the heat storage sheet is used (heat control region; for example, the operating temperature of the heating element). That is, the solvent refers to a solvent that does not undergo a phase change in a liquid state in the heat control region, and is distinguished from a heat storage material that undergoes a phase transition in the heat control region to cause an endothermic and heat dissipation reaction.

The content of the solvent in the core material is not particularly limited, but is preferably less than 30% by mass, more preferably less than 10% by mass, and further preferably 1% by mass or less, based on the total mass of the core material. The lower limit is not particularly limited, but 0% by mass can be mentioned.

Examples of other components that can be included in the microcapsules as a core material include additives such as an ultraviolet absorber, a light stabilizer, an antioxidant, a wax, and an odor suppressant.

[Capsule wall (wall part)]
The microcapsules have a capsule wall that encloses the core material.
The material constituting the capsule wall in the microcapsules is not particularly limited, and examples thereof include polymers, and more specifically, radical polymers, resins having urethane bonds and / or urea bonds, and polyamides.
Hereinafter, each capsule wall will be described in detail.

<Radical polymer>
The radical polymer is a resin formed by radical polymerization of a monomer containing a radically polymerizable polymerizable double bond (ethylenically unsaturated group).
Examples of the monomer (radical polymerizable monomer) from which the radical polymer is derived include (meth) acrylic acid, (meth) acrylic acid esters, (meth) acrylamides, (meth) acrylic acid halide, and styrenes. Examples thereof include radically polymerizable monomers selected from the group consisting of.
The (meth) acrylic acid esters, (meth) acrylamides, (meth) acrylic acid halides, and styrenes may be independently polyfunctional or non-polyfunctional (monofunctional). Good.

Specific examples of the radically polymerizable monomer include the following monomers.
Examples of the radically polymerizable monomer having one polymerizable double bond include (meth) acrylic acid; 2-hydroxyethyl (meth) acrylic acid, 1-hydroxy-2-propyl (meth) acrylic acid, and (meth). 2,3-Dihydroxypropyl acrylate, hydroxymethyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and (meth) (Meta) acrylic acid esters such as benzyl acrylate; (meth) acrylic acid amides such as acrylic acid amide, methacrylic acid and N, N-dimethylacrylic acid amide; acrylic acid such as (meth) acrylic acid chloride Halide; Examples thereof include styrenes such as styrene, hydroxystyrene, and dihydroxystyrene.
Examples of the radically polymerizable monomer having two or more polymerizable double bonds include ethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, and 1,6-hexanediol di (meth) acrylate. , And (poly) alkylene glycol di (meth) acrylates such as 1,9-nonanediol di (meth) acrylate; trimethylpropanthry (meth) acrylate; pentaerythritol tri (meth) acrylate; dipentaerythritol penta (meth). ) Acrylate; Dipentaerythritol hexa (meth) acrylate can be mentioned.

The radically polymerizable monomer preferably contains a polyfunctional radically polymerizable monomer (a radically polymerizable monomer having two or more polymerizable double bonds). That is, it is preferable that the radical polymer has a repeating unit derived from a polyfunctional radically polymerizable monomer.
As the polyfunctional radical-polymerizable monomer, a radical-polymerizable monomer having two or more (preferably 2 to 9, more preferably 2 to 3) polymerizable double bonds is preferable.
The content of the repeating unit derived from the polyfunctional radically polymerizable monomer in the radical polymer is preferably 10% by mass or more, more preferably 20 to 98% by mass, and 20 to 80% by mass with respect to the total mass of the resin. % Is more preferable.

<Resin having urethane bond and / or urea bond>
Examples of the resin having a urethane bond and / or a urea bond include polyurethane, polyurea, and polyurethane urea.

Here, polyurethane is a polymer having a plurality of urethane bonds, and a reaction product of a polyol and a polyisocyanate is preferable.
The polyurea is a polymer having a plurality of urea bonds, and a reaction product of a polyamine and a polyisocyanate is preferable.
The polyurethane urea is a polymer having a urethane bond and a urea bond, and a reaction product of a polyol, a polyamine, and a polyisocyanate is preferable. When polyurethane is produced by reacting a polyol with polyisocyanate, a part of polyisocyanate reacts with water to form polyamine, and as a result, polyurethane urea may be obtained.

As described above, polyurethane, polyurea and polyurethane urea are preferably formed using polyisocyanate.
The polyisocyanate is a compound having two or more isocyanate groups, and examples thereof include aromatic polyisocyanates and aliphatic polyisocyanates.
Examples of the aromatic polyisocyanate include m-phenylenediocyanate, p-phenylenediocyanate, 2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate, naphthalene-1,4-diisocyanate, and diphenylmethane-4,4'-. Diisocyanate, 3,3'-dimethoxy-biphenyldiisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, xylylene-1,4-diisocyanate, xylylene-1,3-diisocyanate, 4-chloroxylylene-1 , 3-Diisocyanate, 2-methylxylylene-1,3-diisocyanate, 4,4'-diphenylpropanediisocyanate, and 4,4'-diphenylhexafluoropropanediisocyanate.

Examples of the aliphatic polyisocyanate include trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, and cyclohexylene-1,3-diisocyanate. , Cyclohexylene-1,4-diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,4-bis (isocyanatemethyl) cyclohexane, 1,3-bis (isocyanatemethyl) cyclohexane, isophorone diisocyanate, lysine diisocyanate, and Hexamethylene diisocyanate can be mentioned.

Although bifunctional aromatic polyisocyanates and aliphatic polyisocyanates have been exemplified above, trifunctional or higher functional polyisocyanates (for example, trifunctional triisocyanates and tetrafunctional tetraisocyanates) are also examples of polyisocyanates. Can be mentioned.
More specifically, the polyisocyanate includes a burette or isocyanurate which is a trimeric of the above bifunctional polyisocyanate, an adduct of a polyol such as trimethylpropane and a bifunctional polyisocyanate, and benzene. Formalin condensate of isocyanate, polyisocyanate having a polymerizable group such as methacryloyloxyethyl isocyanate, and lysine triisocyanate can also be mentioned.
Polyisocyanates are described in the "Polyurethane Resin Handbook" (edited by Keiji Iwata, published by Nikkan Kogyo Shimbun (1987)).

^{As will be described later, a polyisocyanate having an SP value of 30.0 (cal / cm 3} ) ^1/2 or less is preferable, and the SP value is 25, in that the thickness of the capsule wall formed is thinner and more uniform. A polyisocyanate having a concentration of 0.0 (cal / cm ³ ) ^1/2 or less is more preferable. The lower limit of the SP value of the polyisocyanate is not particularly limited, but is preferably ^{14.0 (cal / cm 3} ) ^{1/2 or more.}
When two or more kinds of polyisocyanates are used, it is preferable that the SP value of the polyisocyanate having the highest content is in the upper range.

Polyols are compounds having two or more hydroxy groups, for example, low molecular weight polyols (eg, aliphatic polyols, aromatic polyols), polyether-based polyols, polyester-based polyols, polylactone-based polyols, castor oil-based polyols. , Polyol-based polyols, and hydroxy group-containing amine-based compounds.
The low molecular weight polyol means a polyol having a molecular weight of 300 or less, for example, bifunctional low molecular weight polyols such as ethylene glycol, diethylene glycol, and propylene glycol, as well as glycerin, trimethylolpropane, hexanetriol, and penta. Examples thereof include trifunctional or higher functional low molecular weight polyols such as erythritol and sorbitol.

Examples of the hydroxy group-containing amine compound include amino alcohol, which is an oxyalkylated derivative of an amino compound. Examples of the amino alcohol include N, N, N', N'-tetrakis [2-hydroxypropyl] ethylenediamine, which is a propylene oxide or an ethylene oxide adduct of an amino compound such as ethylenediamine, and N, N, N'. , N'-Tetrakis [2-Hydroxyethyl] ethylenediamine.

A polyamine is a compound having two or more amino groups (primary amino group or secondary amino group), and is a fat such as diethylenetriamine, triethylenetetramine, 1,3-propylenediamine, and hexamethylenediamine. Group polyvalent amines; Polyalkyleneimines (preferably polyethyleneimines); Epoxy compound adducts of aliphatic polyvalent amines; Alicyclic polyvalent amines such as piperazine; 3,9-bis-aminopropyl-2,4,8 , 10-Tetraoxaspiro- (5,5) Undecane and other heterocyclic diamines.
The polyalkyleneimine is a polymer having a repeating unit composed of an amine and an alkylene group, and a polyethyleneimine having a repeating unit composed of an amine and an ethylene group is preferable. The molecular weight of polyalkyleneimine (preferably polyethyleneimine) is not particularly limited, but is preferably 300 to 70,000, more preferably 400 to 50,000. The molecular weight of polyalkyleneimine can be measured by GPC, for example, by the method described in Toyo Soda Research Report Vol. 24, No. 1, P43-49 (1980).

<Polyamide>
Examples of the polyamide include aliphatic polyamides and aromatic polyamides.
The polyamide is preferably a resin obtained by polymerizing, for example, a polyamine (diamine or the like) and a polycarboxylic acid (dicarboxylic acid or the like) and / or a polycarboxylic acid halide (dicarboxylic acid halide or the like).
Examples of the polycarboxylic acid halide include polycarboxylic acid chloride (dicarboxylic acid chloride and the like).
The polycarboxylic acid may be a carboxylic acid anhydride in which carboxylic acid groups are dehydrated and condensed.
Polyamides are polyamines, polycarboxylic acids, and polycarboxylic acid halides in which more than 50% by mass (preferably 75 to 100% by mass, more preferably 90 to 100% by mass) of the total mass of the resin is bonded by an amide bond. It is preferably a repeating unit derived from.

Diamine is preferable as the polyamine from which the repeating unit in polyamide is derived. Examples of polyamines include aliphatic polyamines, alicyclic polyamines, and aromatic polyamines. Examples of the diamine include an aliphatic diamine, an alicyclic diamine, and an aromatic diamine.

As the aliphatic diamine or the alicyclic diamine, for example, a diamine represented by the following general formula (A) can be used. In addition, R ¹ in the following formula represents an aliphatic or alicyclic alkylene group represented by C _n H _{2n (n = 1 to 12).}
H ₂ N-R ^1- NH ₂ ... (A)
Examples of the aromatic diamine include xylylenediamine and metaxylylenediamine.

The polycarboxylic acid from which the repeating unit of the polyamide is derived is preferably a dicarboxylic acid.
Examples of the dicarboxylic acid include an aliphatic dicarboxylic acid, an alicyclic dicarboxylic acid, and an aromatic dicarboxylic acid.
As the aliphatic dicarboxylic acid or the alicyclic dicarboxylic acid, for example, a dicarboxylic acid represented by the following general formula (B) can be used. In addition, R ² in the following formula represents an aliphatic or alicyclic alkylene group represented by C _n H _{2n (n = 4 to 25).}
HOOC-R ^2- COOH ... (B)
Examples of the aliphatic dicarboxylic acid include adipic acid.
Examples of the aromatic dicarboxylic acid include terephthalic acid, methyl terephthalic acid, naphthalenedicarboxylic acid, and isophthalic acid.
As the aromatic dicarboxylic acid, for example, terephthalic acid or isophthalic acid is preferable because it can exhibit excellent properties even at high temperatures.

The polycarboxylic acid halide (polycarboxylic acid chloride or the like) from which the repeating unit of the specific resin which is a polyamide is derived is preferably a dicarboxylic acid halide (dicarboxylic acid chloride or the like).
Examples of the dicarboxylic acid halide include compounds in which the carboxyl group (-COOH) in the above dicarboxylic acid is replaced with a carboxylic acid halide group (-COX, X represents a halogen atom, and a chlorine atom is preferable).

The capsule wall preferably contains a radical polymer, polyurethane urea or polyurea in that the capsule wall containing the above-mentioned polyhydric alcohol can be more easily formed. Among them, the capsule wall preferably contains polyurea or polyurethane urea in that the thickness of the capsule wall can be easily adjusted and microcapsules that are superior to the effects of the present invention can be formed. The capsule wall should contain polyurea or polyurethane urea, which is formed from an aliphatic polyisocyanate, in that a capsule wall can be formed while suppressing the reaction with a polyhydric alcohol, and a microcapsule superior to the effect of the present invention can be formed. Is more preferable.

The content of the capsule wall in the microcapsules is not particularly limited, but is preferably 25% by mass or less, more preferably 15% by mass or less, still more preferably 10% by mass or less, based on the total mass of the core material. When the content of the capsule wall is 15% by mass or less with respect to the total mass of the core material, it indicates that the capsule wall is a thin wall. By making the capsule wall thin, the filling rate of the microcapsules containing the polyhydric alcohol is increased, and as a result, the effect of the present invention becomes more excellent.
The lower limit of the content of the capsule wall is not particularly limited, but in terms of maintaining the pressure resistance of the microcapsules, 1% by mass or more is preferable and 2% by mass or more is more preferable with respect to the total mass of the core material. More preferably by mass% or more.
The content of the capsule wall and the thickness (wall thickness) described later are the amount of the component forming the core material and the amount of the component forming the capsule wall (capsule wall forming material) added in the method for producing microcapsules described later. It can be controlled by changing the conditions such as the ratio with, the dispersion (stirring) condition when preparing the emulsion, and the reaction condition of the capsule wall forming material when forming the capsule wall.

[Physical characteristics of microcapsules]
<Diameter>
The particle size of the microcapsules is not particularly limited, but the median diameter (Dm) based on the volume of the microcapsules is preferably 2 to 1000 μm, more preferably 2 to 500 μm, and even more preferably 7 to 200 μm.
When the microcapsules are used for electronic parts in the form of a heat storage member such as a heat storage sheet described later, the content of the microcapsules per unit volume can be further increased, and the heat storage amount per volume of the heat storage sheet or the heat storage member can be further improved. The particle size of the microcapsules is preferably 100 μm or less, more preferably 50 μm or less in terms of volume-based median diameter (Dm).
The volume-based median diameter of the microcapsules can be controlled by changing the dispersion (stirring) conditions when preparing the emulsion in the method for producing microcapsules described later.

Here, the volume-based median diameter of microcapsules is a grain in which the total volume of particles on the large diameter side and the small diameter side is equal when the entire microcapsule is divided into two with the particle size as a threshold. Refers to the diameter. The volume-based median diameter of the microcapsules is measured by a laser diffraction / scattering method using a Microtrack MT3300EXII (manufactured by Nikkiso Co., Ltd.).
When the microcapsules are contained in the heat storage sheet or the heat storage member, the isolated microcapsules can be obtained by immersing the heat storage sheet or the heat storage member in water for 24 hours or more and centrifuging the obtained aqueous dispersion.

<Wall thickness>
The thickness (wall thickness) of the capsule wall of the microcapsules is not particularly limited, but is preferably 200 μm or less, more preferably 100 μm or less, still more preferably 50 μm or less, in that the content of the contained polyhydric alcohol can be increased. On the other hand, since the strength of the capsule wall can be maintained by having a certain thickness, the wall thickness is preferably 0.05 μm or more, more preferably 0.1 μm or more.
The wall thickness refers to an average value obtained by determining the individual wall thickness (μm) of any 20 microcapsules with a scanning electron microscope (SEM) and averaging them.
Specifically, it is obtained by the following method. First, a liquid in which microcapsules are dispersed is applied onto an arbitrary support and dried to form a coating film. A cross-sectional section of the obtained coating film was prepared, and the cross section was observed by SEM at a magnification of 100 to 5000, and "(value of median diameter based on volume of microcapsules) x 0.9 to (volume basis of microcapsules). Select any 10 microcapsules with a median diameter in the range of) × 1.1 ”and observe the cross section of each selected microcapsule to determine the thickness of the capsule wall. By calculating the average value, the number average wall thickness (μm) of the microcapsules can be obtained.

When the volume-based median diameter of the microcapsules is Dm [unit: μm] and the capsule wall thickness of the microcapsules is δ [unit: μm], the microncaps are micron relative to the volume-based median diameter of the microcapsules. The ratio of the thickness of the capsule wall (δ / Dm) of the capsule is preferably 0.001 to 0.4, preferably 0.003 to 0.3, in that both the heat storage amount and the strength of the microcapsule are excellent in a well-balanced manner. More preferably, 0.005 to 0.2 is further preferable.

Microcapsules are often mononuclear microcapsules.
The fact that the microcapsules are mononuclear means that there is substantially only one space in which the substance (core material) contained in the microcapsules exists. The fact that there is substantially only one space in which the core material exists means that one space (preferably a substantially spherical space) in the microcapsule, which is the largest space in which the core material exists, is. It means that it occupies 50 to 100% by volume (preferably 75 to 100% by volume, more preferably 95 to 100% by volume) with respect to the volume of the total space in which the core material exists. In addition, the volume of one space (preferably a substantially spherical space), which is the largest space in which the core material exists, is 10 times or more the volume of one space, which is the second size. Larger is preferred.
In addition, microcapsules are often substantially spherical.

[Manufacturing method of microcapsules]
The method for producing microcapsules is not particularly limited, and examples thereof include known methods such as an interfacial polymerization method, an internal polymerization method, a phase separation method, an external polymerization method, and a core selvation method. Of these, the interfacial polymerization method is preferable.

<Manufacturing method 1>
An example of a specific embodiment of the method for producing microcapsules (manufacturing method 1) is shown below.
The production method 1 includes a step of preparing an emulsion E containing a polyhydric alcohol, a capsule wall forming material, and ^{a solvent having an SP value of 20 (cal / cm 3} ) ^1/2 or less (emulsion solution preparation step). , A step of reacting a capsule wall forming material to form a capsule wall and forming a microcapsule containing a polyhydric alcohol (encapsulation step).

In the description of the method for producing microcapsules, the capsule wall forming material means a raw material for forming the polymer or resin mentioned as the material constituting the capsule wall. For example, in the case of a capsule wall made of polyurea, the capsule wall forming material contains at least one selected from the group consisting of polyamines and polyisocyanates, and in the case of a capsule wall made of a radical polymer, the capsule wall forming material is a radical. It contains at least one monomer containing a polymerizable polymerizable double bond.
Hereinafter, the manufacturing method 1 will be described in detail.

(Emulsion liquid preparation process)
In the emulsion preparation step, a polyhydric alcohol, a capsule wall forming material, and ^{a solvent having an SP value of 20 (cal / cm 3} ) ^1/2 or less (hereinafter, also referred to as “specific solvent”) are mixed. An emulsion E containing a polyhydric alcohol, a capsule wall forming material, and a specific solvent is prepared.
In the emulsion E prepared by the emulsion preparation step, the polyhydric alcohol is dispersed in the specific solvent, and the capsule wall material exists at the interface between the specific solvent and the polyhydric alcohol.
When two or more kinds of solvents are used, it means that the SP value of the solvent having the highest content is 20 (cal / cm ³ ) ^1/2 or less.

In the emulsion preparation step, the order in which the polyhydric alcohol, the capsule wall forming material, and the specific solvent are mixed is not particularly limited. When mixing the polyhydric alcohol, the capsule wall forming material and the specific solvent, each component may be mixed all at once, or any or all of the polyhydric alcohol, the capsule wall forming material and the specific solvent may be mixed a plurality of times. It may be divided into or sequentially mixed.
Further, at least a part of the polyhydric alcohol and / or at least a part of the capsule wall forming material and at least a part of the specific solvent are mixed and stirred to emulsify, and during this stirring treatment or After that, the remaining components may be added.

The method of dispersing and emulsifying the mixed polyhydric alcohol and / or the capsule wall forming material in a specific solvent is not particularly limited, and is, for example, a homogenizer, a menton gory, an ultrasonic disperser, a dissolver, a keddy mill, or other method. A method using a known disperser can be used.

When two or more kinds of capsule wall forming materials are used, since the capsule wall can be formed after emulsifying the polyvalent alcohol, the particle size of the microcapsules can be easily controlled. The first mixing step of preparing an emulsion E ₀ by mixing at least one of the capsule wall forming materials (first compound) and a solvent having an SP value of 20 (cal / cm ³ ) ^{1/2 or less.} and adding the remaining capsule wall forming material (second compound) to emulsion E _0, it is preferred to have a second mixing step of preparing an emulsion E.
For example, when forming a capsule wall made of polyurea by the production method 1, it is preferable that the first compound added in the first mixing step is polyamine and the second compound added in the second mixing step is polyisocyanate. By first emulsifying a mixed solution in which a polyhydric alcohol and a polyamine are added to a specific solvent _{to prepare an emulsion E 0} , the formation of polyurethane urea due to the reaction between the polyisocyanate and the polyhydric alcohol can be suppressed.

The specific solvent used in the emulsion preparation step is not particularly limited as long as it has an SP value of 20 (cal / cm ³ ) ^1/2 or less, and is, for example, hexane (SP value: 14.9) or heptane (SP). Value: 15.2), octane (SP value: 15.4), diethyl ether (SP value: 16.1), cyclopentyl methyl ether (CMPE, SP value: 17.1), diisopropyl ether (SP value: 15. 3), ethyl acetate (SP value: 18.5), n-butyl acetate (SP value: 17.7), i-butyl acetate (SP value: 17.2), i-propyl acetate (SP value: 17.). 5), toluene (SP value: 18.5), xylene (SP value: 18.3), and benzene (SP value: 19.7) can be mentioned. Further, animal oil, vegetable oil and mineral oil having an SP value of 20 (cal / cm ³ ) ^{1/2 or less may be used.}

The SP value of the specific solvent ^{is preferably 18.5 (cal / cm 3} ) ^1/2 or less, and more preferably 16.5 (cal / cm ³ ) ^1/2 or less. The lower limit is not particularly limited, but is preferably ^{14 (cal / cm 3} ) ^{1/2 or more.}
When two or more kinds of specific solvents are used, it is preferable that the SP value of the specific solvent having the highest content is in the upper range.
As the specific solvent, it is preferable to use a compound that is stable to the polyhydric alcohol and the capsule wall forming material.
The content of the specific solvent is preferably 20 to 98% by mass, more preferably 30 to 90% by mass, based on the total mass of the emulsion E prepared in the emulsion preparation step.

The polyhydric alcohol used in the emulsion preparation process has already been explained. The content of the polyhydric alcohol in the emulsion E is preferably 5 to 80% by mass, more preferably 6 to 70% by mass, based on the total mass of the emulsion E.

The capsule wall forming material used in the emulsion preparation step is also as described above. The content of the capsule wall forming material in the emulsion E is preferably 0.01 to 15% by mass, more preferably 0.05 to 10% by mass, based on the total mass of the emulsion E.
When the emulsion preparation step including the first mixing step and the second mixing step described above is carried out using two or more kinds of capsule wall forming materials, the first compound of the capsule forming material to be mixed with the polyhydric alcohol is used. Of the two or more capsule wall-forming materials, a compound having an active hydrogen group having a higher SP value can be added as the first compound in the first mixing step in that it is evenly contained in the emulsified particles. preferable.
When the capsule wall is polyurea, polyurethane or polyurethane urea, and the capsule wall forming material contains polyisocyanate and polyamine and / or polyol, the first compound is polyamine and / or polyol, and the second compound is polyisocyanate. Is preferable.

When the capsule wall is polyurea, polyurethane or polyurethane urea and the capsule wall forming material contains polyisocyanate and polyamine and / or polyol, the SP value is close to that of the specific solvent, the solubility in the specific solvent is high, and the thickness is high. ^{It is preferable to use a polyisocyanate having an SP value of 30 (cal / cm 3} ) ^1/2 or less, and an SP value of 25 (cal / cm ³ ) ^{1 in} that a thinner and more uniform capsule wall can be formed. It is more preferable to use a polyisocyanate having a ratio of ^{/ 2 or less.} The lower limit of the SP value of the polyisocyanate is not particularly limited, but is preferably ^{13 (cal / cm 3} ) ^{1/2 or more.}
When two or more kinds of polyisocyanates are used, it is preferable that the SP value of the polyisocyanate having the highest content is in the upper range.

An emulsifier may be used in the emulsion preparation step. As the emulsifier, for example, an emulsifier having an HLB value of 0 to 12 is preferable, and an emulsifier having an HLB value of 0 to 10 is more preferable. In the present specification, the HLB value is determined by, for example, the Griffin method.
Emulsifiers with an HLB value of 0-12 include, for example, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan distearate, sorbitan monooleate, sorbitan sesquioleate, sorbitan tristearate, and , Sorbitan trioleate.
As the emulsifier, it is preferable to use a compound that is stable to the polyhydric alcohol and the capsule wall forming material.
The order in which the emulsifier is added is not particularly limited, but when the emulsion preparation step includes the above-mentioned first mixing step and second mixing step, it is preferable to add the emulsifier to the specific solvent in the first mixing step.
The content of the emulsifier is preferably 0.05 to 15% by mass, more preferably 0.1 to 10% by mass, still more preferably 0.3 to 7% by mass, based on the total mass of the emulsion E.

The emulsion E prepared in the emulsion preparation step appropriately contains, if desired, a component that the core material may contain and / or a component that the capsule wall may contain, in addition to the above components. You may.

The emulsion preparation step may be carried out under heating or without heating. The temperature at which the emulsion E ₀ and the emulsion E are prepared by stirring varies depending on the type and combination of each component, but is preferably 20 to 100 ° C, more preferably 30 to 80 ° C. Further, at a temperature equal to or higher than the melting point of the polyhydric alcohol used (more preferably 5 ° C. or higher with respect to the melting point), the polyhydric alcohol, the capsule wall forming material and the specific solvent are mixed and stirred, and the above emulsion E ₀ And the emulsion E is preferably prepared.

(Encapsulation process)
In the encapsulation step, the capsule wall-forming material contained in the emulsion E is reacted to form a capsule wall to form microcapsules containing a polyhydric alcohol.
In the emulsion E prepared in the emulsion preparation step, droplets of polyhydric alcohol are dispersed in a specific solvent, and the capsule wall forming material reacts at the interface between the specific solvent and the polyhydric alcohol to form a capsule wall. Form. The microcapsules thus obtained contain a polyhydric alcohol by the capsule wall.

The reaction of the capsule wall forming material may be carried out under heating or without heating. The reaction temperature varies depending on the type and combination of the capsule wall forming materials, but is preferably 20 to 100 ° C, more preferably 30 to 80 ° C.
The reaction time also varies depending on the type and combination of the capsule wall forming materials, but is preferably 0.5 minutes to 5 hours, more preferably 1 minute to 1 hour.

<Manufacturing method 2>
Another example (manufacturing method 2) of a specific embodiment of the method for producing microcapsules is shown below.
The production method 2 includes a step of mixing a polyhydric alcohol and a monomer having an SP value of 20 (cal / cm ³ ) ^1/2 or less to prepare a first emulsion (first emulsification step). A step of mixing the first emulsion and water to prepare a second emulsion (second emulsification step) and a step of polymerizing a monomer in the second emulsion to form a capsule wall, and many It includes a step of forming microcapsules containing a valent alcohol (encapsulation step).
When two or more kinds of monomers are used, the "monomer having an SP value of 20 (cal / cm ³ ) ^1/2 or less" means that the SP value of the specific solvent having the highest content is 20 (cal / cm). ³ ) It means that it is ^{1/2 or less.}
Hereinafter, the manufacturing method 2 will be described in detail.

(1st emulsification step)
In the first emulsification step, the polyhydric alcohol and ^{a monomer having an SP value of 20 (cal / cm 3} ) ^1/2 or less (hereinafter, also referred to as “specific monomer”) are mixed, and the polyhydric alcohol and the specific monomer are mixed. This is a step of preparing a first emulsified solution (emulsified solution E1) containing and. In the emulsion E1, the polyhydric alcohol is dispersed in the specific monomer.

In the first emulsification step, the method of mixing the polyhydric alcohol and the specific monomer is not particularly limited. All of the polyhydric alcohol and all of the specific monomers may be mixed at once, or either the polyhydric alcohol or the specific monomers may be mixed in a plurality of times or sequentially.
Further, during or after the treatment of mixing at least a part of the polyhydric alcohol and at least a part of the specific monomer and dispersing and emulsifying at least a part of the polyhydric alcohol, the remaining polyhydric alcohol Alternatively, a specific monomer may be added.

As a method of dispersing the mixed polyhydric alcohol in a specific monomer and emulsifying it, for example, a method using a homogenizer, menton gory, ultrasonic disperser, dissolver, keddy mill, or other known disperser can be used. ..

The specific monomer used in the first emulsification step is not particularly limited as long as it has an SP value of 20 (cal / cm ³ ) ^1/2 or less and is a compound that polymerizes to form a capsule wall. For example, radical polymerization Among the monomers containing a possible polymerizable double bond ^{, a compound having an SP value of 20 (cal / cm 3} ) ^1/2 or less can be mentioned. More specifically, for example, styrene (SP value: 18.3), nonanediol dimethacrylate (SP value: 16.8), nonanediol diacrylate (SP value: 17.1), decyl methacrylate (SP value). : 16.7), hexyl methacrylate (SP value: 16.9), hexyl acrylate (SP value: 17.2), trimethylpropantriacrylate (SP value: 17.4), pentaerythritol tetraacrylate (SP) Values: 18.1), trimethylpropantrimethacrylate (SP value: 16.9) and pentaerythritol tetramethacrylate (SP value: 17.0).

The SP value of the specific monomer ^{is preferably 20 (cal / cm 3} ) ^1/2 or less, and more preferably 19 (cal / cm ³ ) ^1/2 or less. The lower limit is not particularly limited, but is preferably ^{14 (cal / cm 3} ) ^{1/2 or more.} When two or more kinds of specific monomers are used, it is preferable that the SP value of the specific monomer having the highest content is in the upper range.
The specific monomer is preferably a compound that is stable to polyhydric alcohols.
The content of the specific monomer is preferably 5 to 90% by mass, more preferably 20 to 80% by mass, based on the total mass of the emulsion E1 prepared in the first emulsification step.

In the first emulsification step, a monomer other than the specific monomer may be contained. Examples of such a monomer include compounds having a SP value of more than 20 (cal / cm ³ ) ^{1/2 among the monomers containing a radically polymerizable polymerizable double bond.} More specifically, for example, methacrylic acid (SP value: 20.6) and ethylene glycol dimethacrylate (SP value: 24.6) can be mentioned.

The polyhydric alcohol used in the first emulsification step has already been explained. The content of the polyhydric alcohol in the emulsion E1 is preferably 10 to 95% by mass, more preferably 20 to 80% by mass, based on the total mass of the emulsion E1.

An emulsifier may be used in the first emulsification step. The emulsifier to be used and its preferred embodiment are the same as those described in the emulsion preparation step of Production Method 1. The amount of the emulsifier added in the first emulsification step is preferably 0.05 to 15% by mass, more preferably 0.1 to 10% by mass, and 0.3 to 7% by mass with respect to the total mass of the emulsion E1. More preferred.

The first emulsification step may be performed under heating or without heating. The first emulsification step varies depending on the type and combination of each component, but is preferably carried out at 20 to 100 ° C, more preferably 30 to 80 ° C. Further, it is preferable to prepare the emulsion E1 by mixing and stirring the polyhydric alcohol and the specific monomer at a temperature equal to or higher than the melting point of the polyhydric alcohol to be used (more preferably 5 ° C. or higher with respect to the melting point).

(Second emulsification step)
The second emulsification step is a step of mixing the emulsified liquid E1 prepared in the first emulsified step with water to prepare a second emulsified liquid (emulsified liquid E2). The emulsion E2 prepared in the second emulsification step is a W / O / W type three-component composite emulsion in which droplets of a specific monomer containing a polyhydric alcohol are dispersed in water.

In the second emulsification step, the method of mixing the emulsion E1 and water is not particularly limited, and the mixture may be mixed according to the method described in the first emulsification step, and the disperser described in the first emulsification step is used. The emulsion E1 may be dispersed in water.

The content of water used in the second emulsification step is not particularly limited, but is preferably 5 to 95% by mass, more preferably 10 to 80% by mass, and 15 to 75% by mass with respect to the total mass of the emulsion E2. More preferred.

Further, when the specific monomer is a monomer containing a polymerizable double bond capable of radical polymerization and a capsule wall made of a radical polymer is formed in the encapsulation step described later, a water-soluble radical polymerization initiator is added to water. Is preferable. Examples of the water-soluble radical polymerization initiator include a water-soluble azo polymerization initiator and a water-soluble peroxide such as potassium persulfate.
The content of the water-soluble radical polymerization initiator is preferably 0.0001 to 5% by mass, more preferably 0.01 to 1% by mass, based on the total mass of water.

An emulsifier may be used in the second emulsification step. The emulsifier to be used and its preferred embodiment are the same as those described in the emulsion preparation step of Production Method 1. Further, in the second emulsification step, a water-soluble polymer such as polyvinyl alcohol (PVA) and polyacrylic acid as an emulsifier, and a surfactant having an HLB value of 6 to 20 (preferably 8 to 17) are used. You may.
The amount of the emulsifier added in the second emulsification step is preferably 0.05 to 15% by mass, more preferably 0.1 to 10% by mass, and 0.3 to 5% by mass with respect to the total mass of the emulsion E2. More preferred.

The emulsion E1 prepared in the first emulsification step and the emulsion E2 prepared in the second emulsification step may contain, if desired, components and / or the above-mentioned core materials in addition to the above-mentioned components. Ingredients that may be contained in the capsule wall of the above may be appropriately contained.

(Encapsulation process)
In the encapsulation step, a specific monomer is polymerized in the emulsion E2 prepared in the second emulsification step to form a capsule wall to form microcapsules containing a polyhydric alcohol.
In the emulsion E2 prepared in the second emulsification step, as described above, droplets in which the specific monomer contains a polyhydric alcohol are dispersed in water. By polymerizing a specific monomer in such an emulsion E2 to form a capsule wall, microcapsules in which a polyhydric alcohol is encapsulated by the capsule wall can be obtained.

The polymerization in the encapsulation step is preferably carried out under heating. The reaction temperature in the polymerization varies depending on the type and combination of the specific monomer and other monomers contained arbitrarily, but is preferably 40 to 100 ° C, more preferably 50 to 90 ° C.
The polymerization reaction time also varies depending on the type and combination of the specific monomer and other monomers contained arbitrarily, but is preferably 0.5 to 20 hours, more preferably 1 to 10 hours.
In the encapsulation step, it is preferable to sufficiently stir the emulsion E2 in order to suppress the aggregation of the microcapsules. Further, a dispersant may be added to the emulsion E2.

<Manufacturing method 3>
Another example (manufacturing method 3) of a specific embodiment of the method for producing microcapsules is shown below.
The production method 3 involves preparing an emulsion containing polyhydric alcohol, a capsule wall-forming material, and water (emulsion solution preparation step), and reacting the capsule wall-forming material in the emulsion to form a capsule wall. It includes a step of forming and forming microcapsules containing a polyhydric alcohol (encapsulation step).
Hereinafter, the manufacturing method 3 will be described in detail.

(Emulsion liquid preparation process)
The emulsion preparation step is not particularly limited as long as the above emulsion can be obtained, and for example, a first mixing step and a first mixing step of mixing a polyhydric alcohol and a capsule wall forming material to prepare a mixed solution. It has a second mixing step of mixing water with the mixed solution prepared in (1) to prepare an emulsion containing polyhydric alcohol, capsule wall forming material and water.
The emulsion prepared by the emulsion preparation step is an oil-in-water (O / W) type in which droplets of a mixed solution (oil phase) containing polyhydric alcohol and a capsule wall-forming material are dispersed in an aqueous phase containing water. Emulsion.
By performing the first mixing step to prepare a uniform mixed solution of the polyhydric alcohol and the capsule wall forming material, an emulsion having a more uniform composition of dispersed droplets can be prepared.

When two or more kinds of capsule wall forming materials are used, the capsule wall can be formed after emulsifying the polyvalent alcohol, and the particle size of the microcapsules can be easily controlled. A first mixing step of mixing at least one wall-forming material (first compound) to prepare a mixed solution, a mixed solution prepared in the first mixing step, and water are mixed to prepare a polyhydric alcohol. , The second mixing step of preparing the first emulsion containing the capsule wall-forming material and water, and the first emulsion and the remaining capsule wall-forming material (second compound) are mixed to prepare the second emulsion. It is preferable to have a third mixing step.

For example, when the capsule wall made of polyurea is formed by using polyisocyanate and polyamine as the capsule wall forming material by the production method 3, the first compound used in the first mixing step is polyisocyanate and the third The second compound used in the mixing step is preferably a polyamine.
Further, when a capsule wall made of polyurethane urea is formed by using a polyisocyanate polyol adduct body and a polyamine as a capsule wall forming material by the production method 3, the first compound used in the first mixing step is a polyisocyanate polyol. It is an adduct body, and it is preferable that the second compound used in the third mixing step is a polyamine.
The second mixing step includes a case where the mixed solution prepared in the first mixing step and an emulsifier aqueous solution obtained by dissolving the emulsifier in water are mixed to prepare a first emulsion.

The polyisocyanate is preferably an aliphatic polyisocyanate, and more preferably a polyisocyanate in which at least one of the carbon atoms to which the isocyanate group is bonded is a secondary carbon atom. The isocyanate group is bonded to the secondary carbon atom, that is, the carbon atom bonded to the nitrogen atom of the isocyanate group is a carbon atom contained in the aliphatic hydrocarbon group, and the nitrogen atom is described above. In addition to this, it means that it is bonded to two carbon atoms and one hydrogen atom.
Although such a polyisocyanate reacts with a polyamine, its reactivity with a polyhydric alcohol is low, and the formation of polyurethane urea due to the reaction between the polyisocyanate and the polyhydric alcohol can be suppressed. As a result, the filling rate of the polyhydric alcohol contained in the microcapsules can be improved.

Examples of the aliphatic polyisocyanate include those similar to those described above.
Examples of the polyisocyanate in which at least one of the carbon atoms to which the isocyanate group is bonded is a secondary carbon atom include propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, and cyclohexylene-1,2. -Diisocyanate, cyclohexylene-1,3-diisocyanate, cyclohexylene-1,4-diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, isophorone diisocyanate, and lysine diisocyanate are mentioned, and isophorone diisocyanate is preferably used.

In the above emulsion, from the viewpoint of suppressing the distribution of the polyhydric alcohol from the oil phase to water, a solvent having an SP value of 2 (cal / cm ³ ) ^1/2 _{or more of the polar term δ P} is used as the polyhydric alcohol. It may be added to the mixed solution with the capsule wall forming material. The solvent and the polyhydric alcohol may or may not be uniformly mixed.
From the viewpoint of suppressing the distribution of the polyhydric alcohol from the oil phase to the aqueous phase and improving the filling rate of the polyhydric alcohol contained in the microcapsules, the polar term δ _P of the SP value is 2.0 to 6.6. A solvent is preferable, a solvent of 2.5 to 6.3 is more preferable, and a solvent of 3.0 to 6.0 is further preferable.
The solvent is not particularly limited as long as it is within the above SP value, and is, for example, cyclopentylmethyl ether (CMPE, δ _P : 3.5), diisopropyl ether (δ _P : 3.3), ethyl acetate. (Δ _P : 6.3), n-butyl acetate (δ _P : 4.7), i-butyl acetate (δ _P : 4.5), i-propyl acetate (δ _P : 5.1), toluene ( δ _P : 2.6), xylene (δ _P : 2.3) and the like can be mentioned.

An emulsifier may be used in the emulsion preparation step of the production method 3. As the emulsifier, for example, an emulsifier having an HLB value of 8 to 20 is preferable, and an emulsifier having an HLB value of 10 to 18 is more preferable.
Examples of emulsifiers having an HLB value of 8 to 20 include decaglyceryl monostearate, decaglyceryl monomyristate, decaglyceryl monooleate, decaglyceryl monolaurate, hexaglyceryl monostearate, hexaglyceryl monomyristate, and monolaurin. Examples thereof include decaglyceryl acid, polyoxyethylene polyoxypropylene cetyl ether, and polyoxyethylene sorbitan monooleate.
The content of the emulsifier is preferably 0.05 to 15% by mass, more preferably 0.1 to 10% by mass, still more preferably 0.3 to 7% by mass, based on the total mass of the emulsion.

The emulsion preparation step may be performed under heating or without heating. The temperature at which the above emulsion is prepared by stirring varies depending on the type and combination of each component, but is preferably 20 to 100 ° C, more preferably 30 to 80 ° C.

(Encapsulation process)
In the encapsulation step, the capsule wall-forming material contained in the emulsion is reacted to form a capsule wall to form microcapsules containing a polyhydric alcohol.
In the emulsion prepared in the emulsion preparation step, an oil phase consisting of droplets of polyhydric alcohol is dispersed in the aqueous phase containing water, and capsules are formed at the interface between the aqueous phase and the polyhydric alcohol which is the oil phase. The wall-forming material reacts to form a capsule wall. The microcapsules thus obtained contain a polyhydric alcohol by the capsule wall.

The reaction of the capsule wall forming material may be carried out under heating or without heating. The reaction temperature varies depending on the type and combination of the capsule wall forming materials, but is preferably 20 to 100 ° C, more preferably 30 to 80 ° C.
The reaction time also varies depending on the type and combination of the capsule wall forming materials, but is preferably 0.5 minutes to 5 hours, more preferably 1 minute to 1 hour.

The polyhydric alcohol and capsule wall forming material used in the production method 3, the mixing method of each component in the emulsion preparation step, and the production conditions other than the above are as described in the production methods 1 and 2.

[Heat storage sheet]
The heat storage sheet according to the first embodiment of the present invention is a heat storage sheet containing microcapsules containing a polyhydric alcohol as a heat storage material as a main component.
The heat storage sheet according to the second embodiment of the present invention is a heat storage sheet containing a heat storage composition containing a polyhydric alcohol as a heat storage material as a main component.

The heat storage sheet of the first embodiment and the heat storage sheet of the second embodiment (hereinafter, also simply referred to as “heat storage sheet”) are polyvalent alcohols contained in the heat storage sheet (particularly, the polyvalent alcohol contained in the core portion of the microcapsules). The heat storage function is exhibited by the transfer of heat accompanying the phase change between solid and liquid of alcohol). This makes it possible, for example, to absorb and release heat in a heating element that emits heat. The heat storage sheet of the present invention exhibits a more excellent heat storage function by containing microcapsules or a heat storage composition having an excellent heat storage amount per volume. This makes it possible to provide a heat storage sheet and a heat storage member (described later) capable of storing a larger amount of heat per volume than in the prior art.

<Microcapsules>
The heat storage sheet according to the first embodiment includes microcapsules. Since the details of the microcapsules are as described above, the description thereof will be omitted here.
The content of the microcapsules in the heat storage sheet is not particularly limited, but is preferably 50% by mass or more, more preferably 65% by mass or more, still more preferably 75% by mass or more, based on the total mass of the heat storage sheet. The upper limit of the content of the microcapsules is not particularly limited, but is preferably 99.9% by mass or less, more preferably 99% by mass or less, based on the total mass of the heat storage sheet.

<Heat storage composition>
The heat storage sheet according to the second embodiment contains a heat storage composition containing a polyhydric alcohol as a main component.
When the heat storage composition "contains a polyhydric alcohol as a main component", it means that the component having the highest content among the components contained in the heat storage composition is the polyhydric alcohol.
When the heat storage composition contains two or more kinds of polyhydric alcohols, "containing the polyhydric alcohol as a main component" means that the total content of the two or more kinds of polyhydric alcohols is contained in the microcapsules. It means that it is higher than other components other than valent alcohol.
As described above, the polyhydric alcohol has a high heat storage amount per unit mass and has two or more hydroxy groups in the molecule, so that hydrogen bonds between the molecules are appropriately formed and the polyhydric alcohol has a high density. Therefore, the heat storage composition containing a polyhydric alcohol as a main component has an excellent heat storage amount per unit volume.

The heat storage composition may be the same as that described for the core material encapsulated in the microcapsules, including its preferred composition and embodiment.
That is, the heat storage composition may contain a polyhydric alcohol as a main component, and may contain a second heat storage material, a solvent, and additives such as a flame retardant. The details of the polyhydric alcohol, the second heat storage material, and the solvent are as described above, and thus the description thereof will be omitted here.

The content of the heat storage composition in the heat storage sheet is not particularly limited, but is preferably 50% by mass or more, more preferably 65% by mass or more, still more preferably 75% by mass or more, based on the total mass of the heat storage sheet. The upper limit of the content of the heat storage composition is not particularly limited, but is preferably 99.9% by mass or less, more preferably 99% by mass or less, based on the total mass of the heat storage sheet.

<Binder>
The heat storage sheet preferably contains a binder in addition to the microcapsules and / or the heat storage composition. Since the heat storage sheet contains a binder, the durability of the heat storage sheet is improved.

The binder is not particularly limited as long as it is a polymer capable of forming a film, and examples thereof include a water-soluble polymer and an oil-soluble polymer.
"Water-soluble" in a water-soluble polymer means that the amount of the target substance dissolved in 100% by mass of water at 25 ° C. is 5% by mass or more, and a more suitable water-soluble polymer has a dissolved amount of 10% by mass. It means that it is the above.
"Oil-soluble" in an oil-soluble polymer means that the amount of the target substance dissolved in 100% by mass of water at 25 ° C. is less than 5% by mass.

Examples of the water-soluble polymer include polyvinyl alcohol (unmodified polyvinyl alcohol and modified polyvinyl alcohol), polyacrylic acid amide and its derivatives, ethylene-vinyl acetate copolymer, styrene-maleic anhydride copolymer, and ethylene-maleic anhydride. Copolymers, isobutylene-maleic anhydride copolymers, polyvinylpyrrolidone, ethylene-acrylic acid copolymers, vinyl acetate-acrylic acid copolymers, carboxymethyl cellulose, methyl cellulose, casein, gelatin, starch derivatives, gum arabic, and Examples include sodium alginate.

Examples of the oil-soluble polymer include acrylic resin, polyolefin, styrene-butadiene resin, polyurethane, polyurea, and PET (Polyethylene terephthalate) resin. The polymer having heat storage property described in International Publication No. 2018/2038787 and JP-A-2007-031610 may be used.

The content of the binder in the heat storage sheet is not particularly limited, but is preferably 0.1 to 20% by mass, more preferably 1 to 11% by mass, in terms of the balance between the film strength of the heat storage sheet and the heat storage property of the heat storage member.

<Other ingredients>
The heat storage sheet may contain components other than microcapsules, a heat storage composition and a binder. Other components include thermally conductive materials, flame retardants, UV absorbers, antioxidants, solvents, colorants, gelling agents, monomers, and preservatives.
The content of the other components is preferably 10% by mass or less, more preferably 5% by mass or less, based on the total mass of the heat storage sheet. The lower limit is not particularly limited, but 0% by mass can be mentioned.
Regarding the "thermal conductivity" of the thermally conductive ^{material, a material having a thermal conductivity of 10 Wm -1} K ^-1 or more is preferable. Among them, the thermal conductivity of the heat conductive material ^{is more preferably 50 Wm -1} K ^-1 or more in that the heat dissipation of the heat storage sheet is improved.
The thermal conductivity (unit: Wm ^-1 K ^-1 ) is a value measured by a flash method at a temperature of 25 ° C. by a method compliant with Japanese Industrial Standards (JIS) R1611.

<Physical characteristics of heat storage sheet>
(thickness)
The thickness of the heat storage sheet is not particularly limited, but is preferably 1 to 1000 μm.
The thickness is determined by observing the cut surface of the heat storage sheet cut in parallel with the thickness direction with SEM, measuring 5 arbitrary points, and averaging the thicknesses of the 5 points.

(Latent heat capacity)
Although latent heat of the heat storage sheet is not particularly limited, high heat storage of the heat storage member, in that it is suitable for temperature adjustment of the heating element generates heat, preferably 150 J / cm ³ or more, 180 J / cm ³ or more preferably , 200 J / cm ³ or more is more preferable. The upper limit is not particularly limited, but in many cases it is ^{300 J / cm 3 or less.}
The latent heat capacity is a value calculated from the amount of heat storage per unit mass (J / g) measured by differential scanning calorimetry (DSC) and the density of the heat storage sheet (g / cm ^3). .. The density of the heat storage sheet is measured using a dry automatic densitometer (product name "AccuPyc1330", manufactured by Shimadzu Corporation).

(Elastic modulus)
The elastic modulus (tensile elastic modulus) of the heat storage sheet is not particularly limited, but is preferably 1700 MPa or more, more preferably 2000 MPa or more, further preferably 3700 MPa or more, and particularly preferably 4000 MPa or more.
The upper limit of the elastic modulus of the heat storage sheet is not particularly limited, but is preferably 10,000 MPa or less.
The elastic modulus (tensile elastic modulus) of the heat storage sheet is measured according to JIS K 7161-1: 2014.

<Manufacturing method of heat storage sheet>
The method for producing the heat storage sheet (including the heat storage sheet of the first embodiment or the heat storage sheet of the second embodiment; the same applies hereinafter) is not particularly limited, and known methods can be mentioned.
For example, in the case of the heat storage sheet of the first embodiment, a solution (or dispersion) containing the above microcapsules and the above components such as a binder used as needed is applied onto a substrate and dried. A method of producing by allowing the mixture to be used can be mentioned. Another method is to prepare a composition containing the above-mentioned microcapsules and the above-mentioned components such as a binder by melt-forming a film on a base material.
Further, in the case of the heat storage sheet of the second embodiment, a mixed solution containing the above heat storage composition and the above components such as a binder used as needed is applied onto the base material and dried. The method of producing in is mentioned. Another method is to prepare a composition containing the above heat storage composition and the above components such as a binder by melt-forming a film on a base material.
If necessary, a simple substance of the heat storage sheet can be obtained by peeling the base material from the laminate of the obtained base material and the heat storage sheet.

Examples of the base material include a resin base material, a glass base material, and a metal base material. Examples of the resin contained in the resin base material include polyester (eg, polyethylene terephthalate, polyethylene naphthalate), polyolefin (eg, polyethylene, polypropylene), and polyurethane. Further, it is preferable to add a function to improve the thermal conductivity in the surface direction or the film thickness direction and to rapidly diffuse heat from the heat generating portion to the heat storage portion to the base material. A base material formed by combining a metal base material and a heat conductive material such as a graphene sheet is more preferable.
The thickness of the base material is not particularly limited, but is preferably 1 to 100 μm, more preferably 1 to 25 μm, still more preferably 3 to 15 μm.
The surface of the base material is preferably treated for the purpose of improving the adhesion to the heat storage sheet. Examples of the surface treatment method include corona treatment, plasma treatment, and application of a thin layer which is an easy-adhesion layer.

The material constituting the easy-adhesion layer is not particularly limited, and examples thereof include resins, and more specific examples thereof include styrene-butadiene rubber, urethane resin, acrylic resin, silicone resin, and polyvinyl resin.
The thickness of the easy-adhesion layer is not particularly limited, but is preferably 0.1 to 5 μm, more preferably 0.5 to 2 μm.
As the base material, a peelable temporary base material may be used.

Examples of the coating method include a die coating method, an air knife coating method, a roll coating method, a blade coating method, a gravure coating method, and a curtain coating method.

The drying temperature is preferably 20 to 130 ° C., more preferably 30 to 120 ° C., and even more preferably 33 to 100 ° C.
The drying time may be completed immediately before the moisture in the membrane is completely dried, and is preferably 30 seconds or longer, more preferably 1 minute or longer. The shorter the upper limit of the drying time, the better from the viewpoint of the production efficiency of the heat storage sheet.
In the drying step, the coating film may be flattened. Examples of the flattening treatment method include a method of applying pressure to the coating film with a device such as a roller, a nip roller, and a calendar to increase the filling rate of the polyhydric alcohol in the film.

<Use of heat storage sheet>
The heat storage sheet of the present invention can be applied to various uses, for example, electronic devices (for example, mobile phones (particularly smartphones), mobile information terminals, personal computers (particularly portable personal computers), game machines, and Remote control, etc.); Automotive components (eg, batteries (particularly lithium-ion batteries), LED lamps, LCD monitors); Building materials suitable for temperature control during rapid temperature rise during the day or indoor heating and cooling (eg,) Floor materials, roofing materials, wall materials, etc.); Clothing suitable for temperature adjustment in response to changes in environmental temperature or changes in body temperature during exercise or rest (for example, underwear, jackets, cold protection clothes, gloves, etc.) ); Bedding; It can also be used for applications such as an exhaust heat utilization system that stores unnecessary exhaust heat and uses it as heat energy.
Further, the microcapsules of the present invention and the heat storage composition of the present invention can also be applied to the above-mentioned applications.

Among them, the heat storage sheet is preferably used for an electronic device (particularly, a portable electronic device). The reason for this is as follows.
As a method of suppressing the temperature rise due to heat generation of the electronic device, a method of discharging heat to the outside of the electronic device by an air flow and a method of diffusing heat to the entire housing of the electronic device by a heat pipe or a heat spreader are used. I came. However, from the viewpoint of thinning and waterproofing of electronic devices in recent years, the airtightness of electronic devices has improved, and it is difficult to adopt a method of discharging heat by the flow of air. Then, a method of diffusing heat over the entire housing of the electronic device is used. Therefore, there is a limit to suppressing the temperature rise of the electronic device.
To solve this problem, by introducing the above heat storage sheet into the electronic device, it is possible to suppress the temperature rise of the electronic device while maintaining the airtightness and waterproofness of the electronic device. That is, since the heat storage sheet provides a portion in the electronic device that can store heat for a certain period of time, the surface temperature of the heating element in the electronic device can be maintained in an arbitrary temperature range.

[Heat storage member]
The heat storage member has the above-mentioned heat storage sheet (including the heat storage sheet of the first embodiment or the heat storage sheet of the second embodiment).
The heat storage member may further have a protective layer. Further, the heat storage member preferably has a base material on the heat storage sheet from the viewpoint of handling.

<Base material>
The base material of the heat storage member is as described above.

<Protective layer>
The protective layer is a layer arranged on the heat storage sheet, and when the heat storage member has a base material, the protective layer is arranged on the surface side of the heat storage sheet opposite to the base material. The protective layer has a function of protecting the heat storage sheet.
The protective layer may be arranged so as to be in contact with the heat storage sheet, or may be arranged on the heat storage sheet via another layer.
The material constituting the protective layer is not particularly limited, and a resin is preferable, and a resin selected from the group consisting of a fluororesin and a siloxane resin is preferable in that water resistance and flame retardancy are improved.

As the protective layer, for example, a layer containing a known hard coating agent or a hard coating film described in JP-A-2018-202696, JP-A-2018-183877, and JP-A-2018-111793 may be used. Good. Further, from the viewpoint of heat storage, a protective layer having a polymer having heat storage, which is described in International Publication No. 2018/20387 and JP-A-2007-031610, may be used.

The protective layer may contain components other than the resin. Other components include thermally conductive materials, flame retardants, UV absorbers, antioxidants, and preservatives.

The thickness of the protective layer is not particularly limited, but is preferably 50 μm or less, more preferably 0.01 to 25 μm, and even more preferably 0.5 to 15 μm.
The thickness is determined by observing the cut surface obtained by cutting the protective layer in parallel with the thickness direction with SEM, measuring 5 arbitrary points, and averaging the thicknesses of the 5 points.

The method for forming the protective layer is not particularly limited, and known methods can be mentioned. For example, a method in which a protective layer forming composition containing a resin or a precursor thereof is brought into contact with a heat storage sheet, and a coating film formed on the heat storage sheet is subjected to a curing treatment as necessary, and protection. A method of laminating the layers on the heat storage sheet can be mentioned.
Hereinafter, the method of using the protective layer forming composition will be described in detail.

<Adhesion layer>
For the purpose of improving the adhesion between the heating element and the heat storage sheet, which will be described later, the adhesion layer may be arranged on the surface side of the base material opposite to the heat storage sheet. Examples of the adhesive layer include an adhesive layer and an adhesive layer.
The material of the pressure-sensitive adhesive layer is not particularly limited, and examples thereof include known pressure-sensitive adhesives.
Examples of the pressure-sensitive adhesive include an acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, and a silicone-based pressure-sensitive adhesive. In addition, as another example of the adhesive, "Characteristic evaluation of release paper / release film and adhesive tape and its control technology", Information Mechanism, 2004, Acrylic adhesive described in Chapter 2, UV curable adhesive , And silicone adhesives.
The acrylic pressure-sensitive adhesive refers to a pressure-sensitive adhesive containing a polymer ((meth) acrylic polymer) of a (meth) acrylic monomer.
The adhesive layer may further contain a tackifier.

The material of the adhesive layer is not particularly limited, and examples thereof include known adhesives.
Examples of the adhesive include urethane resin adhesives, polyester adhesives, acrylic resin adhesives, ethylene vinyl acetate resin adhesives, polyvinyl alcohol adhesives, polyamide adhesives, and silicone adhesives.

The method for forming the adhesive layer is not particularly limited, and for example, a method of transferring the adhesive layer onto the heat storage sheet and a method of applying a pressure-sensitive adhesive or a composition containing an adhesive onto the heat storage sheet to form the adhesive layer. Can be mentioned.
The thickness of the adhesion layer is not particularly limited, but is preferably 0.5 to 100 μm, more preferably 1 to 25 μm, still more preferably 1 to 15 μm.

<Other members>
The heat storage member includes a base material arranged on the surface side opposite to the protective layer in the heat storage sheet, an adhesion layer arranged on the surface side opposite to the heat storage sheet in the base material, and the base material in the adhesion layer. It may have a temporary base material arranged on the opposite surface side to the above. As a result, damage to the heat storage sheet can be suppressed during storage and transportation of the heat storage member.
The base material and the adhesive layer are as described above. Moreover, the specific example of the temporary base material is the same as the specific example of the base material. A base material having a peeled surface is preferable.
When using the heat storage member, the temporary base material is peeled off from the heat storage member.

[Electronic device]
The electronic device of the present invention has the above-mentioned heat storage member and a heating element.
The heat storage member (heat storage sheet, adhesion layer and protective layer) is as described above.

<Heating element>
The heating element is a member that may generate heat in an electronic device, and is, for example, a SoC such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), a SRAM (Static Random Access Memory), and an RF (Radio Frequency) device. (Systems on a Chip), cameras, LED packages, power electronics, and batteries (especially lithium-ion secondary batteries).
The heating element may be arranged so as to be in contact with the heat storage member, or may be arranged on the heat storage member via another layer (for example, a heat conductive material described later).

<Heat conductive material>
The electronic device further preferably has a heat conductive material.
The heat conductive material means a material having a function of conducting heat generated from a heating element to another medium.
As the "thermal conductivity" of the heat conductive material, it is preferable that ^{the heat conductivity is 10 Wm -1} K ^{-1 or more.} That is, the heat conductive material is preferably a material having a thermal conductivity of 10 Wm ^-1 K ^-1 or more. The thermal conductivity (unit: Wm ^-1 K ^-1 ) is a value measured by a flash method at a temperature of 25 ° C. by a method compliant with Japanese Industrial Standards (JIS) R1611.
Examples of the heat conductive material that the electronic device may have include a heat radiating sheet and silicon grease, and the heat radiating sheet is preferably used.
The electronic device preferably includes the above-mentioned heat storage member, a heat conductive material, and a heating element.

(Heat dissipation sheet)
The heat radiating sheet is a sheet having a function of conducting heat generated from a heating element to another medium, and preferably has a heat radiating material. Examples of the heat radiating material include carbon, metal (for example, silver, copper, aluminum, iron, platinum, stainless steel, and nickel), and silicon.
Specific examples of the heat radiating sheet include a copper foil sheet, a metal film resin sheet, a metal-containing resin sheet, and a graphene sheet, and the graphene sheet is preferably used. The thickness of the heat radiating sheet is not particularly limited, but is preferably 10 to 500 μm, more preferably 20 to 300 μm.

<Other members>
The electronic device may include a protective layer, a heat storage sheet, a heat conductive material, a heating element, and other members other than the heat transport member described above. Examples of other members include a base material and an adhesion layer. The base material and the adhesive layer are as described above.

Specific examples of electronic devices are as described above, so the description thereof will be omitted.

Hereinafter, the present invention will be described in more detail with reference to Examples. The present invention is not limited to the following examples as long as the gist of the present invention is not exceeded.

[Example A (Preparation of microcapsules)]
[Example A1]
Microcapsules A1 were produced according to the above-mentioned method 2 for producing microcapsules.
In a container made of SUS (Steel Use Stainless) with a capacity of 200 mL, 1,8-octanediol (10 g), styrene (SP value: 18.3) (3.2 g), 1,9-nonanediol dimethacrylate (SP value:) 16.8) (1.25 g) and glycerin monostearate (emulsifier) (0.2 g) were added. The container was placed in a water bath and heated to 65 ° C. to melt the 1,8-octanediol. At this time, it was confirmed that the mixed solution was separated into two layers. The mixture was stirred at 3000 rpm for 5 minutes to obtain an emulsion A11.
An aqueous PVA solution (60 g) containing 1% by mass of polyvinyl alcohol (PVA) and 0.02% by mass of sodium nitrite at a liquid temperature of 65 ° C. was added to the emulsion A11 and stirred at 2000 rpm. Subsequently, the mixture was stirred at 65 ° C. under a nitrogen stream at 300 rpm for 20 minutes to obtain an emulsion A12. A solution (2.5 g) containing 1% by mass of AIBN (azobisisobutyronitrile) as a polymerization initiator in toluene was added dropwise to the emulsion A12, stirred at 65 ° C. for 3 hours, and then the mixed solution was 85. The temperature was raised to ° C., and the mixture was further stirred for 2 hours.
The emulsion A12 was cooled to 65 ° C. and then filtered. The resulting filtrate was washed with heptane. As a result, microcapsules A1 having a capsule wall made of acrylic resin and containing 1,8-octanediol were obtained.
As PVA (Polyvinyl alcohol), Kuraray Poval (registered trademark) KL-318 (manufactured by Kuraray Co., Ltd .; PVA) was used.

[Example A2]
Microcapsules A2 were produced according to the above-mentioned method 1 for producing microcapsules.
After adding 1,8-octanediol (10 g) and polyethyleneimine (weight average molecular weight (Mw) = 600) (0.4 g) as a capsule wall forming material (first compound) to a SUS container having a capacity of 200 mL. , Heptane (SP value: 15.2) (25 g) was further added. The container was placed in a water bath and heated to 65 ° C. to melt the 1,8-octanediol. At this time, it was confirmed that the mixed solution was separated into two layers. After adding sorbitan trioleate (emulsifier) (3 g), the mixture was stirred at 2000 rpm for 3 minutes to obtain an emulsion A2.
While stirring the emulsion A2 and maintaining the liquid temperature, a solution prepared by dissolving hexamethylene diisocyanate (1 g) in heptane (1.5 g) was added dropwise to the emulsion A2 over 3 minutes. After stirring for 10 minutes from the end of the dropping, the emulsion A2 was filtered. The filtered product was washed by pouring heptane at a liquid temperature of 65 ° C. over the obtained filtered product. As a result, microcapsules A2 having a polyurea capsule wall and containing 1,8-octanediol were obtained.

[Example A3]
Similar to Example A2, it has a polyurea capsule wall and 1,8-octanediol, except that the amount of hexamethylene diisocyanate added is changed to 3.5 g and the amount of polyethyleneimine added is changed to 1.2 g. A microcapsule A3 containing the above was obtained.

[Example A4]
Polyurea capsules in the same manner as in Example A2, except that the amount of hexamethylene diisocyanate added was changed to 0.5 g, the amount of polyethyleneimine added was changed to 0.2 g, and the rotation speed was changed to 800 rpm. Microcapsules A4 having a wall and containing 1,8-octanediol were obtained.

[Example A5]
Similar to Example A2, it has a polyurea capsule wall and 3,6-dithia-1,8-octanediol, except that 1,8-octanediol was changed to 3,6-dithia-1,8-octanediol. Microcapsules A5 containing 8-octanediol were obtained.

[Example A6]
Microcapsules A6 having a polyurea capsule wall and containing 1,8-octanediol were prepared in the same manner as in Example A2, except that hexamethylene diisocyanate was changed to 1,3-bis (isocyanatemethyl) cyclohexane. Obtained.

[Example A7]
Microcapsules A7 having a polyurea capsule wall and containing 1,10-decanediol were obtained in the same manner as in Example A2 except that 1,8-octanediol was changed to 1,10-decanediol. It was.

[Example A8]
Microcapsules A8 were produced according to the above-mentioned method 3 for producing microcapsules.
To a container made of SUS having a capacity of 200 mL, 20 g of water and 0.18 g of NIKKOL (registered trademark) Decaglin 1-M (Nikko Chemicals Co., Ltd., emulsifier, decaglyceryl monomyristate) were added to obtain an aqueous solution of the emulsifier. The container was placed in a water bath and the temperature was raised to 50 ° C.
A 1,8-octanediol (4.5 g) was placed in a container made of SUS different from the above, and the temperature was raised to 60 ° C. to melt the 1,8-octanediol. To this, 0.8 g of Takenate (registered trademark) D-140 (Trimethylolpropane adduct of isophorone diisocyanate, manufactured by Mitsui Chemicals, Inc.) was added to obtain a uniform mixed solution. The obtained mixed solution was added to the above aqueous solution of the emulsifier over 15 seconds with stirring at 400 rpm. The mixture was stirred at the same stirring speed for 120 seconds, and then 2.5 g of a 10 mass% polyethyleneimine (Mw = 600) aqueous solution was added dropwise over 40 seconds. The stirring speed was lowered to 200 rpm, the mixture was stirred at the same temperature (60 ° C.) for 1 hour, and then the mixed solution was filtered. As a result, microcapsules A8 having a capsule wall made of polyurethane urea and containing 1,8-octanediol were obtained.

[Example A9]
To a container made of SUS having a capacity of 200 mL, 20 g of water and 0.18 g of NIKKOL Decaglin 1-M (Nikko Chemicals Co., Ltd., emulsifier, decaglyceryl monomyristate) were added to obtain an aqueous solution of the emulsifier. The container was placed in a water bath and the temperature was raised to 50 ° C.
Add 1,8-octanediol (3.6 g) to another SUS container, then add cyclopentyl methyl ether (3.6 g) and heat to 60 ° C. to add 1,8-octanediol and Cyclopentyl methyl ether was melted. To this, 0.8 g of Takenate D-140 (Mitsui Chemicals, Inc., isophorone diisocyanate trimethylolpropane adduct) was added to obtain a uniform mixed solution. The obtained mixed solution was added to the above aqueous solution of the emulsifier over 15 seconds with stirring at 400 rpm. After stirring the mixture at the same stirring speed for 120 seconds, 2.5 g of a 10 mass% polyethyleneimine (Mw = 600) aqueous solution was added dropwise to the mixture over 40 seconds. The stirring was lowered to 200 rpm, and the mixture was stirred at the same temperature (60 ° C.) for 1 hour, and then the mixture was filtered. As a result, microcapsules A9-2 having a capsule wall made of polyurethane urea and containing a cyclopentyl methyl ether solution of 1,8-octanediol were obtained.
Next, the obtained microcapsules A9-2 were dried in a blower dryer at 80 ° C. for 24 hours to evaporate cyclopentyl methyl ether, thereby having a capsule wall made of polyurethane urea and having a capsule wall of 1,8-octane. Microcapsules A9 containing diol were obtained.

[Example A10]
It has a polyurethane urea capsule wall and has a polyurethane urea capsule wall in the same manner as in Example A9, except that Takenate D-140 is changed to Takenate D-160 (Mitsui Chemicals, Inc., trimethylolpropane adduct of hexamethylene diisocyanate). , 8-Octanediol-encapsulating microcapsules A10 were obtained.

[Example A11]
Similar to Example A9, it has a polyurea capsule wall, except that Takenate D-140 was changed to VESTANAT® T1890E (Isocyanurate of isophorone diisocyanate, manufactured by Sumika Covestro Urethane). Microcapsules A11 containing 1,8-octanediol were obtained.

[Example A12]
Microcapsules A12 having a polyurethane urea capsule wall and containing 1,10-decanediol in the same manner as in Example A9, except that 1,8-octanediol was changed to 1,10-decanediol. Obtained.

[Comparative Example A1]
7.2 g of n-docosane (latent heat storage material; melting point 43 ° C., carbon number 22 aliphatic hydrocarbon purity 98.0%) was heated and dissolved at 60 ° C. to obtain Solution A to which 12.0 g of ethyl acetate was added. ..
Further, 0.4 g of a trimethylolpropane adduct (Bernock D-750, DIC Corporation) of tolylene diisocyanate dissolved in 1 g of methyl ethyl ketone was added to the stirring solution B to obtain a solution B.
Then, the above solution C is added to a solution prepared by dissolving 0.74 g of polyvinyl alcohol (Clarepovar (registered trademark) KL-318 (manufactured by Clare Co., Ltd .; PVA (Polyvinyl alcohol)) as a binder in 14.0 g of water. 25.0 g of water was added to the emulsified solution after emulsification and dispersion, and 1.0 g of a 10 mass% aqueous solution of polyethyleneimine (weight average molecular weight (Mw) = 600) was added thereto to obtain the product. The solution was heated to 70 ° C. with stirring, and after continuing stirring for 1 hour, it was cooled to 30 ° C.. Further water was added to the cooled solution to adjust the concentration, and n having a capsule wall of polyvinyl urea. A dispersion of microcapsules containing docosan was obtained. The solid content concentration of the dispersion was 14% by mass.
A part of the dispersion liquid of the obtained n-docosane-encapsulating microcapsules is filtered under normal pressure, and the obtained filtrate is washed with water to have a polyurethane urea capsule wall and contain n-docosane. Capsules A7 were obtained.
Kuraray Poval KL-318 used as the polyvinyl alcohol is a modified polyvinyl alcohol having a carboxy group or a salt thereof as a modifying group.

[Evaluation]
The microcapsules obtained in the above Examples or Comparative Examples were evaluated.

(Median diameter (average particle size))
The volume-based median diameter of the microcapsules produced in each example was measured using Microtrac MT3300EXII (manufactured by Nikkiso Co., Ltd.). The median diameter (μm) of the microcapsules produced in each example is shown in Table 1 described later.

(Heat absorption, density)
For the microcapsules produced in each example, the content of the core material (filling rate, unit: mass%) with respect to the total mass of the microcapsules is the ratio of the amount of heat of the heat storage material to the amount of heat of the microcapsules ([heat amount of heat storage material]. / [The amount of heat as a microcapsule]) was calculated.
The density (g / cm ³ ) of the microcapsules produced in each example was measured using a dry automatic densitometer (product name "AccuPyc1330", manufactured by Shimadzu Corporation).
The heat absorption amount per unit mass (J / g) of the microcapsules produced in each example and the heat absorption amount (J / g) per unit mass of the polyhydric alcohol (or core material) contained in each microcapsule are determined. It was measured using a differential scanning calorimetry meter (DSC).
From the density of the microcapsules (g / cm ³ ) and the heat absorption amount per unit mass of the microcapsules (J / g), the heat absorption amount per unit volume of the microcapsules produced in each example (J / cm ³ ) is calculated. Calculated.

Table 1 shows the physical characteristics of the microcapsules produced in Examples A1 to A6 and Comparative Example A1.
In Table 1, the "type" column of "multihydric alcohol (core material)" indicates the compounds contained as the core material in the microcapsules prepared in each example.
The "n" column of "multihydric alcohol (core material)" indicates the numerical value of n when the polyhydric alcohol is represented by the formula (2).
The "Molecular weight" column, "Melting point (° C)" column and "Heat absorption (J / g)" column of "Polyvalent alcohol (core material)" are the molecular weight, melting point and differential scanning of the compound contained as the core material, respectively. The amount of heat absorption (J / g) per unit mass measured using calorimetry (DSC) is shown.
The "capsule wall" column indicates the type of material constituting the capsule wall in the microcapsules produced in each example.
The "microcapsules" column shows the physical characteristics of the microcapsules produced in each example.
The "median diameter (μm)" column indicates the volume-based median diameter of the microcapsules.
The "filling rate (mass%)" column indicates the content (mass%) of the core material (heat storage material) with respect to the total mass of the microcapsules.
The "Density (g / cm ³ )" column indicates the density (g / cm ³ ) of the microcapsules.
The "heat absorption amount (J / cm ³ )" column indicates the heat absorption amount (J / cm ³ ) per unit volume of the microcapsules.

From the results shown in the table, it was confirmed that the microcapsules of the present invention have an excellent amount of heat storage per unit volume.

When the median diameter is the same, it was confirmed that the microcapsules whose capsule wall material is polyurea have a higher filling rate and higher heat absorption per unit volume than the microcapsules whose capsule wall material is acrylic resin. (Comparison of Example A1 and Example A2).

[Example B (Preparation of heat storage sheet)]
[Example B1]
The microcapsules A2 (30 g) obtained in Example A2 were added to a mixed solution of heptane (120 g) and isopropanol (30 g). Auridic WNN-153 (manufactured by DIC Corporation, acrylic resin) (3.1 g) was added to the obtained mixed solution as a binder to obtain a heat storage sheet forming composition B1.
Separately from this, an optical adhesive sheet MO-3015 (thickness: 5 μm) manufactured by Lintec Corporation was attached to a PET substrate having a thickness of 6 μm to form an adhesive layer, and a PET substrate with an adhesive layer was prepared.
The heat storage sheet forming composition B1 was applied to the surface of the PET substrate on the adhesive layer side using a bar coater, and the obtained coating film was dried at 80 ° C. for 25 minutes. This coating and drying treatment was repeatedly carried out to form a heat storage member B1 having a thickness of 300 μm on the PET substrate. Then, the PET base material was peeled off from the heat storage member B1 to obtain a heat storage sheet B1.

[Example B2]
A heat storage sheet B2 having a thickness of 300 μm was used in the same manner as in Example B1 except that the microcapsules A4 (30 g) obtained in Example A4 were used instead of the microcapsules A2 obtained in Example A2. Made.

[Example B3]
A heat storage sheet B3 having a thickness of 300 μm was used in the same manner as in Example B1 except that the microcapsules A9 (30 g) obtained in Example A9 were used instead of the microcapsules A2 obtained in Example A2. Made.

[Evaluation]
The heat storage sheet obtained in the above example was evaluated.

(Heat absorption per unit volume of heat storage sheet, filling rate)
The obtained heat storage sheet B1 was cut into 1 cm squares, and the density (g / cm ³ ) of the obtained sample was measured using a dry automatic densitometer (product name "AccuPyc1330", manufactured by Shimadzu Corporation).
The heat storage sheet B1 was shredded, and the heat absorption amount (J / g) per mass of the shredded heat storage sheet B1 was measured using differential scanning calorimetry (DSC). The heat absorption amount per unit volume of the heat storage sheet B1 (J / cm ³ ) was calculated from the density (g / cm ^{3) of the heat storage sheet B1 and the heat absorption amount per mass (J / g).}
The heat absorption amount (J / g) of 1,8-octanediol contained in the heat storage sheet B1 as a heat storage material was measured by using differential scanning calorimetry (DSC). From the heat absorption amount (J / g) per mass of the heat storage sheet B1 and the heat absorption amount (J / g) of 1,8-octanediol, the content of 1,8-octanediol with respect to the total mass of the heat storage sheet B1 ( Filling rate) (mass%) was calculated.
Similarly for the heat storage sheets B2 and B3, the density (g / cm ³ ) of the heat storage sheet B1 and the heat absorption amount per mass (J / g) are measured, and the heat absorption amount per unit volume of the heat storage sheet B1 (J). / Cm ³ ) and filling rate (mass%) were calculated.

Table 2 shows the evaluation results of the heat storage sheets prepared in Examples B1, B2 and B3.
In Table 2, the "type" column and the "median diameter (μm)" column of "microcapsules" indicate the type of microcapsules used in each example and the volume-based median diameter, respectively.
The "heat storage sheet" column shows the physical characteristics of the heat storage sheets produced in Examples B1 and B2.
The "sheet density (g / cm ³ )" column indicates the density of the heat storage sheet (g / cm ³ ).
Column "endotherm (J / g)" column and "endothermic quantity (J / cm ^3)" is the amount of heat absorbed per unit mass of the heat storage sheet (J / g) and the amount of heat absorbed per unit volume (J / cm ³ ) Are shown respectively.
The "filling rate (mass%)" column indicates the content (mass%) of the core material (heat storage material) with respect to the total mass of the heat storage sheet.

From the results shown in the table, it was confirmed that the heat storage sheet produced by using the microcapsules of the present invention has an excellent heat storage amount per unit volume.

Further, when a heat storage sheet is produced using the microcapsules of the present invention, the smaller the particle size of the microcapsules, the more the filling rate of the heat storage material can be increased, and as a result, the amount of heat storage per unit volume of the entire heat storage sheet. (Comparison of Example B1 and Example B2).

[Example C]
The physical characteristics of the polyhydric alcohol contained in the microcapsules of the present invention were evaluated. More specifically, 1,8-octanediol, 3,6-dithia-1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol, 1,9-nonanediol, and 1, For 11-undecanediol, the density (g / cm ³ ) of each compound in a solid state and the amount of heat absorption per unit mass (J / g) were measured, and the amount of heat absorption per unit volume (J / cm ^{3) of each compound was measured.} ) Was calculated. All of the above compounds are polyhydric alcohols represented by the above formula (2).
Similarly, for docosan, 1-octadecane and n-octadecane, the density (g / cm ³ ) and heat absorption per unit mass (J / g) of each compound in a solid state were measured, and each compound was measured. The amount of heat absorbed per unit volume (J / cm ³ ) was calculated.
The density (g / cm ³ ) of each compound was measured using a dry automatic density meter (product name "AccuPyc1330", manufactured by Shimadzu Corporation). The heat absorption amount (J / g) per unit mass of each compound was measured using a differential scanning calorimetry meter (DSC).

Table 3 shows the physical characteristics of each compound.
In Table 3, the "Compound name" column indicates the compound whose physical properties have been measured.
The “n” column indicates the numerical value of n when the polyhydric alcohol is represented by the above formula (2).
The "molecular weight" column, "melting point (° C.)" column, "density (g / cm ³ )", "heat absorption amount (J / g)" column and "heat absorption amount (J / cm ³ )" column are for each compound. The molecular weight, melting point, density, heat absorption per unit mass (J / g) and heat absorption per unit volume (J / cm ³ ) measured using differential scanning calorimetry (DSC) are shown.
However, the heat absorption amount (J / g) per unit mass of n-octadecane described as Reference Example C1 is a literature value.

From the results shown in the table, it was confirmed that the above-mentioned polyhydric alcohol is excellent in the amount of heat storage per unit volume.
On the other hand, docosane, 1-octadecanol and n-octadecane mentioned as Comparative Example C1, Comparative Example C2 and Reference Example C1 have not so much difference in the amount of heat absorbed per unit mass, but the amount of heat absorbed per unit volume. As seen, it was confirmed that it was significantly inferior to the polyhydric alcohol used in the present invention. Therefore, when microcapsules containing these heat storage materials are produced, it is considered that an excellent heat absorption amount per unit volume as in the microcapsules of the present invention cannot be achieved.
Further, it was confirmed that the effect of the present invention is more excellent when n is an even number of 8 or more in the polyhydric alcohol represented by the formula (2) (comparison of Examples C1 to C6).

Example A2 except that each of the above 1,12-dodecanediol, 1,9-nonanediol, 1,11-undecanediol and 1,2-decanediol was used in place of 1,8-octanediol. In the same manner as above, microcapsules having a polyurea capsule wall and containing each polyhydric alcohol were prepared, and the obtained microcapsules were evaluated for medium diameter, filling rate, density and heat absorption per unit volume. ..
As a result, it was confirmed that the median diameter of each microcapsule was 40 μm, and the filling rate, density and heat absorption per unit volume were similar to those of Examples A2, A5 and A7.

Claims (20)

1. Microcapsules containing polyhydric alcohol as the main component.
2. The microcapsule according to claim 1, wherein the content of the polyhydric alcohol is 60% by mass or more with respect to the total mass of the microcapsule.
3. The microcapsule according to claim 1 or 2, wherein the polyhydric alcohol has a molecular weight of 100 to 500.
4. The microcapsule according to any one of claims 1 to 3, wherein the polyhydric alcohol contains a compound represented by the following formula (1).
   HO-R ^1- OH (1)
   In the formula, R ¹ is an aliphatic hydrocarbon group having 8 or more carbon atoms or a group in which one or more carbon atoms constituting the aliphatic hydrocarbon group having 8 or more carbon atoms are substituted with heteroatoms. Represents a divalent linking group. However, the hydroxy group in the formula (1) and the two groups selected from the hetero atom do not bond with each other.
5. The microcapsule according to any one of claims 1 to 4, wherein the polyhydric alcohol contains a compound represented by the following formula (2).
   HO- (R ² ) _n- OH (2)
   In the formula, R ² independently represents a methylene group, —O— or —S—. n represents an integer of 8 or more. However, the two groups selected from the hydroxy group, —O— and —S— in the formula (2) do not bond to each other.
6. The microcapsule according to claim 5, wherein n is an even number of 8 or more.
7. The microcapsule according to any one of claims 1 to 6, wherein the polyhydric alcohol has a melting point of 90 ° C. or lower.
8. The microcapsule according to any one of claims 1 to 7, wherein the capsule wall contains at least one selected from the group consisting of polyurea and polyurethane urea.
9. The microcapsule according to any one of claims 1 to 7, wherein the capsule wall contains an acrylic resin.
10. The microcapsule according to any one of claims 1 to 9, wherein the volume-based median diameter of the microcapsule is 100 μm or less.
11. A heat storage composition containing a polyhydric alcohol having a molecular weight of 100 to 500 as a main component.
12. The heat storage composition according to claim 11, wherein the polyhydric alcohol contains a compound represented by the following formula (1).
    HO-R ^1- OH (1)
    In the formula, R ¹ is an aliphatic hydrocarbon group having 8 or more carbon atoms or a group in which one or more carbon atoms constituting the aliphatic hydrocarbon group having 8 or more carbon atoms are substituted with heteroatoms. Represents a divalent linking group. However, the hydroxy group in the formula (1) and the two groups selected from the hetero atom do not bond with each other.
13. The heat storage composition according to claim 11 or 12, wherein the polyhydric alcohol contains a compound represented by the following formula (2).
    HO- (R ² ) _n- OH (2)
    In the formula, R ² independently represents a methylene group, —O— or —S—. n represents an integer of 8 or more. However, the two groups selected from the hydroxy group, —O— and —S— in the formula (2) do not bond to each other.
14. The heat storage composition according to claim 13, wherein n is an even number of 8 or more.
15. The heat storage composition according to any one of claims 11 to 14, wherein the polyhydric alcohol has a melting point of 90 ° C. or lower.
16. A heat storage sheet containing the microcapsules according to any one of claims 1 to 10 or the heat storage composition according to any one of claims 11 to 15.
17. The method for producing microcapsules according to any one of claims 1 to 10.
    A step of preparing an emulsion containing the polyhydric alcohol, a capsule wall forming material, and ^{a solvent having an SP value of 20 (cal / cm 3} ) ^{1/2 or less.}
    A step of reacting the capsule wall forming material to form a capsule wall to form the microcapsules containing the polyhydric alcohol, and a step of forming the microcapsules.
    A method for manufacturing microcapsules, including.
18. The production method according to claim 17, wherein the capsule wall forming material contains polyisocyanate and polyamine.
19. The method for producing microcapsules according to any one of claims 1 to 10.
    A step of mixing the polyhydric alcohol with a monomer having an SP value of 20 (cal / cm ³ ) ^1/2 or less to prepare a first emulsion, and a step of preparing the first emulsion.
    A step of mixing the first emulsion and water to prepare a second emulsion, and
    A step of polymerizing the monomer in the second emulsion to form a capsule wall and forming the microcapsules containing the polyhydric alcohol.
    A method for manufacturing microcapsules, including.
20. The method for producing microcapsules according to any one of claims 1 to 10.
    A step of mixing the polyhydric alcohol and a capsule wall forming material to prepare a mixed solution, and
    A step of mixing the mixed solution with water to prepare an emulsion, and
    A step of reacting the capsule wall-forming material in the emulsion to form a capsule wall to form the microcapsules containing the polyhydric alcohol.
    A method for manufacturing microcapsules, including.