WO2022044658A1

WO2022044658A1 - Microcapsules, method for producing microcapsules, heat-storage sheet, method for producing heat-storage sheet, and heat-storage object

Info

Publication number: WO2022044658A1
Application number: PCT/JP2021/027732
Authority: WO
Inventors: 秀樹冨澤; 高史松井; 貴彦山崎
Original assignee: 富士フイルム株式会社
Priority date: 2020-08-25
Filing date: 2021-07-27
Publication date: 2022-03-03
Also published as: JPWO2022044658A1

Abstract

The present invention addresses the problem of providing microcapsules superior in the stability over time of heat storage amount per unit volume. Furthermore, the present invention addresses the problem of providing a method for producing the microcapsules, a heat-storage sheet, a method for producing the heat-storage sheet, and a heat-storage object.　The microcapsules according to the present invention comprise cores and shells containing the cores enclosed therein, wherein the cores comprise an aliphatic amine and the shells have a water vapor permeability of 10^-1 g/(m²·day) or less.

Description

Microcapsules, microcapsule manufacturing method, heat storage sheet, heat storage sheet manufacturing method, heat storage

The present invention relates to microcapsules, a method for manufacturing microcapsules, a heat storage sheet, a method for manufacturing a heat storage sheet, and a heat storage body.

Microcapsules may provide new value to customers in terms of enclosing and protecting functional materials such as heat storage materials, fragrances, dyes, adhesive curing agents, and pharmaceutical ingredients. .. In recent years, microcapsules containing a phase change substance (PCM: Phase Change Material) such as paraffin and functioning as a heat storage material for storing heat generated outside have been attracting attention. The heat storage material is included in and used as a heat storage member that stores heat from a heating element and suppresses an increase in overall temperature in equipment such as electronic devices, buildings, automobiles, and waste heat utilization systems.

Examples of the material having a high heat storage amount include an aliphatic amine having an aliphatic hydrocarbon group and an amino group. For example, in Patent Document 1, the primary capsule having an inner shell on the surface of the core agent is a microcapsule for curing an epoxy resin further coated with an outer shell, and the core agent is a basic curing agent and / or a curing acceleration. The invention relating to the epoxy resin curing microcapsule which is an agent is disclosed.

Japanese Unexamined Patent Publication No. 2016-035056

Patent Document 1 describes nitrogen-containing compounds such as imidazole compounds, amine compounds, and hydrazide compounds as basic curing agents and / or curing accelerators constituting the core of microcapsules.
As a result of examining the heat storage property of the microcapsules containing the aliphatic amine with reference to Patent Document 1, the present inventors have found that the microcapsules containing the aliphatic amine per unit volume as time passes from the preparation. It was found that there is a problem that the amount of heat storage decreases.

In view of the above, it is an object of the present invention to provide microcapsules having more excellent stability of heat storage amount per unit volume over time. Another object of the present invention is to provide a method for manufacturing microcapsules, a heat storage sheet, a method for manufacturing a heat storage sheet, and a heat storage body.

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]
A microcapsule having a core and a shell containing the core, wherein the core contains an aliphatic amine and the water vapor transmission rate of the shell is 10 ^-1 g / (m ² · day) or less. capsule.
[2]
The microcapsule according to [1], wherein the water vapor transmission rate of the shell is ^10-2 g / (m ² · day) or less.
[3]
The microcapsule according to [1] or [2], wherein the aliphatic amine is an aliphatic polyamine having two or more amino groups.
[4]
The microcapsule according to any one of [1] to [3], wherein the aliphatic amine has a linear aliphatic hydrocarbon group having an even number of carbon atoms.
[5]
The microcapsule according to any one of [1] to [4], wherein the aliphatic amine has a linear aliphatic hydrocarbon group having an even number of 6 to 16 carbon atoms.
[6]
The microcapsule according to any one of [1] to [5], wherein the aliphatic amine has a melting point of 37 to 100 ° C.
[7]
The microcapsule according to any one of [1] to [6], wherein the shell has an inorganic layer made of an inorganic compound.
[8]
The microcapsule according to [7], wherein the core and the inorganic layer are in direct contact with each other.
[9]
The microcapsule according to [7] or [8], wherein the inorganic compound is an inorganic oxide.
[10]
The microcapsule according to any one of [7] to [9], wherein the inorganic compound is a compound containing at least one element selected from the group consisting of Si, Al, Zr, Hf and Ti.
[11]
The microcapsule according to any one of [1] to [10], wherein the shell has a thickness of 5 to 100 nm.
[12]
The microcapsule according to any one of [1] to [11], wherein the core has a particle size of 0.1 to 500 μm.
[13]
The method for producing microcapsules according to any one of [1] to [12], wherein a core preparation step for preparing a core containing an aliphatic amine and a shell containing the core are placed on the surface of the core. A method for producing microcapsules, which comprises a shell forming step for forming, and carries out the core preparation step and the shell forming step in an environment where the aliphatic amine and water do not come into contact with each other.
[14]
The method for producing microcapsules according to [13], wherein the shell forming step is carried out in a nitrogen atmosphere having a dew point of −60 ° C. or lower and a purity of 99.9% by volume or more.
[15]
The method for producing microcapsules according to [13] or [14], wherein the shell forming step includes a step of forming an inorganic layer made of an inorganic compound by a dry vapor deposition method.
[16]
A heat storage sheet containing the microcapsules according to any one of [1] to [12] and a binder.
[17]
The step of preparing a coating liquid by mixing the microcapsules, the binder, and the solvent according to any one of [1] to [12], which is the method for producing a heat storage sheet according to [16], and the above-mentioned coating. A method for producing a heat storage sheet, comprising a step of applying a liquid on a substrate to form a coating film and a step of drying the coating film.
[18]
A heat storage body comprising the microcapsule according to any one of [1] to [12] and a binder.

According to the present invention, it is possible to provide microcapsules having more excellent stability over time in the amount of heat storage per unit volume. Further, according to the present invention, it is possible to provide a method for manufacturing microcapsules, a heat storage sheet, a method for manufacturing a heat storage sheet, and a heat storage body.

Hereinafter, the present invention will be described in detail.
It should be noted that the description of the constituent elements relating to the embodiment of the present invention may be made based on the typical embodiment of the present invention, but the present invention is not limited to such an embodiment.

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.
In the numerical range described in the present specification stepwise, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of the numerical range described in another stepwise description. 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.
The various components described below may be used alone or in combination of two or more. For example, the aliphatic amine described later may be used alone or in combination of two or more.
In the present specification, the amount of each component in the composition, layer or mixture is the above-mentioned plurality of substances present in the composition, layer or mixture when a plurality of substances corresponding to the component are present, unless otherwise specified. Means the total amount of.

As used herein, (meth) acrylate represents acrylate and methacrylate, and (meth) acrylic represents acrylic and methacrylic.
In the present specification, "preparation" means not only the act of synthesizing and / or blending a specific material, but also the act of procuring a predetermined product by purchase or the like.
As used herein, "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, a combination of two or more preferred embodiments is a more preferred embodiment.

[Microcapsules]
The microcapsules of the present invention are microcapsules having a core and a shell containing the core, wherein the core contains an aliphatic amine and the water vapor transmission rate of the shell is 10 ^-1 g / (m ² · day) or less. Is.

Although the detailed mechanism by which the above-mentioned effects of the present invention can be obtained by the microcapsules of the present invention is not clear, the present inventors presume that, for example, the decrease in heat storage amount over time was suppressed for the following reasons. ing.
The aliphatic amine contained in the microcapsules of the present invention has a high heat storage amount per unit mass, and since hydrogen bonds between molecules are moderately formed by amino groups and has a high density, the heat storage amount per unit volume is high. Is considered to be high. In the microcapsules of the present invention, the core containing the aliphatic amine is surrounded by a shell having a high gas barrier property having a water vapor permeability of 10 ^-1 g / (m ² · day) or less, so that a period has passed since the production of the microcapsules. It is presumed that the contained aliphatic amine was not denatured even after the above, and the decrease in the amount of heat storage per unit volume with time was further suppressed.
Hereinafter, the fact that the heat storage amount per unit volume of the microcapsules is more excellent in stability with time is also described as “the effect of the present invention is more excellent”.

The microcapsule has a core and a shell for containing the core material (encapsulating material (also referred to as an inclusion component)) forming the core. As used herein, the shell is also referred to as a "capsule wall".

〔core〕
Microcapsules contain at least an aliphatic amine as a core material (encapsulating component). Since the aliphatic amine is encapsulated in microcapsules, it can stably exist in a phase state depending on the temperature.

<Alphatic amine>
The aliphatic amine contained in the microcapsules is not particularly limited as long as it is an amine compound having a main chain skeleton containing an aliphatic hydrocarbon group and at least one amino group.

In the main chain skeleton, for example, one or more carbon atoms constituting a chain or cyclic aliphatic hydrocarbon group and a chain or cyclic aliphatic hydrocarbon group are represented by -NR-2. Examples thereof include a group substituted with a valent group (R represents a hydrogen atom or an aliphatic hydrocarbon group which may have an amino group).
The main chain skeleton of the aliphatic amine is preferably linear in that the amount of heat storage per unit volume is more excellent. The fact that the main chain skeleton of an aliphatic amine is linear means that the main chain skeleton is one of carbon atoms constituting a linear aliphatic hydrocarbon group or a linear aliphatic hydrocarbon group. It means that more than one is a group formed by substituting a secondary amino group (> NH).
Further, in the aliphatic amine, it is preferable that the main chain skeleton does not have a substituent in that the amount of heat storage per unit volume is more excellent.

When the main chain skeleton of the aliphatic amine has an aliphatic hydrocarbon group, the carbon number thereof is preferably 4 or more, more preferably 6 or more, still 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 12 or less is more preferable, in that the melting point is in a preferable range described later and the density is higher. Further, it is preferable that the aliphatic amine has a linear aliphatic hydrocarbon group having an even number of carbon atoms in that the amount of heat storage per unit volume is more excellent.
When the main chain skeleton is a group in which one or more of the carbon atoms constituting the aliphatic hydrocarbon group are substituted with a divalent group represented by -NR-, the total number of carbon atoms and nitrogen atoms is used. However, it is preferable that it is included in the above range.
The aliphatic amine preferably has a linear aliphatic hydrocarbon group having an even number of 6 to 16 carbon atoms, and has a linear aliphatic hydrocarbon group having 8, 10 or 12 carbon atoms. It is more preferable to have.

Examples of the amino group contained in the aliphatic amine include a primary amino group (-NH ₂ ), a secondary amino group (> NH), and a tertiary amino group (> N-), which are primary. An amino group or a secondary amino group is preferable, and a primary amino group is more preferable.
The number of amino groups contained in the aliphatic amine is not particularly limited, but the aliphatic amine is preferably an aliphatic polyamine having two or more amino groups in that the amount of heat storage per unit volume is more excellent. The number of amino groups contained in the aliphatic polyamine is more preferably 2 to 4, and even more preferably 2 or 3. Among them, an aliphatic diamine having two amino groups is particularly preferable in that the hydrogen bond between the two molecules and the van der Waals force of the aliphatic hydrocarbon group become stronger and the density in the core portion is improved.

Examples of the aliphatic diamine include compounds represented by the following formula (1).
H ₂ N-R ¹ -NH ₂ (1)
In the formula, R ¹ is a divalent group in which one or more carbon atoms constituting an aliphatic hydrocarbon group having 4 or more carbon atoms or an aliphatic hydrocarbon group having 4 or more carbon atoms is represented by -NR-. A group substituted with a group (R represents a hydrogen atom or an aliphatic hydrocarbon group which may have an amino group) is represented. However, the amino group in the formula (1) and the divalent group represented by -NR- do not bind to each other.

In the formula (1), as the aliphatic hydrocarbon group in ^R1 , a linear alkylene group having 6 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 amount of heat storage per unit volume is more excellent. When R ¹ has a divalent group represented by -NR-, the total number of carbon atoms and nitrogen atoms is preferably the above number.

Among the aliphatic amines, the aliphatic monoamine having one amino group in the molecule includes, for example, dimethylamine, diethylamine, n-butylamine, tert-butylamine, n-hexylamine, cyclohexylamine, n-octylamine, and , 2-Ethylhexylamine.
Among the aliphatic amines, examples of the aliphatic diamine having two amino groups in the molecule include 1,4-diaminobutane, 1,6-diaminohexane, 1,7-diaminoheptane, and 1,8-diaminooctane. , 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane, 1,13-diaminotridecane, 1,14-diaminotetradecane, and 1,16-diamino. Hexadecane can be mentioned.
Among the aliphatic amines, examples of the aliphatic polyamine having three or more amino groups in the molecule include diethylenetriamine, triethylenetetramine, and tetraethylenepentamine.

As the aliphatic amine, 1,4-diaminobutane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,11 -Diaminoundecane or 1,12-diaminododecane is preferred, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, or 1,10-diaminodecane. , 1,6-diaminohexane, 1,8-diaminooctane, or 1,10-diaminodecane is even more preferred, and 1,8-diaminooctane, or 1,10-diaminodecane is particularly preferred.

Aliphatic amines may form salts with counterions. Examples of the salt of the aliphatic amine include a salt with an inorganic acid in which at least one non-metal selected from the group consisting of Cl, S, N and P is bonded to hydrogen. In addition, in this specification, "aliphatic amine" also includes an embodiment in which an aliphatic amine forms a salt with a counterion.
The aliphatic amine preferably does not form a salt.

The molecular weight of the aliphatic amine is not particularly limited, but 100 to 300 is preferable, and 100 to 200 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 aliphatic amine is preferably close to the operating temperature of an electronic device (particularly a small or portable electronic device) and is excellent in applicability to an electronic device, and is preferably 100 ° C. or lower, more preferably 85 ° C. or lower. 70 ° C. or lower is more preferable. The lower limit is not particularly limited, but is preferably 10 ° C. or higher, more preferably 25 ° C. or higher, and even more preferably 37 ° C. or higher.

The aliphatic amine may be used alone or in combination of two or more. When a plurality of aliphatic amines 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 aliphatic amine. When it is substantially one type, the aliphatic amine is encapsulated in microcapsules with high purity, so that the endothermic property is good. Here, the fact that the aliphatic amine is substantially one kind means that the content of the compound having the highest content among the aliphatic amines is 95 to 100% by mass with respect to the total mass of the aliphatic amine. It means that it is preferably 98 to 100% by mass.

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

The content of the aliphatic amine in the microcapsules is not particularly limited, but is preferably 75% by volume or more, more preferably 85% by volume or more, more preferably 90% by volume, based on the total volume of the microcapsules, in that the heat storage property is more excellent. Volume% or more is particularly preferable. The upper limit of the content of the aliphatic amine is not particularly limited, but is preferably 99.9% by volume or less, more preferably 99.5% by volume or less, based on the total volume of the microcapsules, in terms of being superior in strength. 99% by volume or less is more preferable.

(density)
The density of the aliphatic amine 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 it is often 2.0 g / cm ³ or less.

(Latent heat capacity)
The latent heat capacity of the aliphatic amine is preferably high, preferably 200 J / cm ³ or more, and more preferably 250 J / cm ³ or more. The upper limit is not particularly limited, but it is often 500 J / cm ³ or less.
The latent heat capacity is the heat storage amount per unit mass (J / g) of the aliphatic amine measured by differential scanning calorimetry (DSC) and the density of the aliphatic amine measured by the 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 (encapsulating component). In this specification, the second heat storage material does not contain the above-mentioned aliphatic amine.
The type of the second heat storage material is not particularly limited as long as it is a heat storage material other than the aliphatic amine. As the second heat storage material, a material that changes phase in response to a temperature change can be used, and the phase change between the solid phase and the liquid phase that accompanies the state change of melting and solidification in response to the temperature change can be repeated. A material that can be used 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.

The second heat storage material includes, for example, a material that can store heat generated outside the microcapsule as sensible heat, and a material that can store heat generated outside the microcapsule as latent heat (hereinafter, "latent heat storage material"). Also referred to as), a material that causes a phase change due to a reversible chemical change, or the like may be used. 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 ease of control of the amount of heat that can be transferred and received and the size of the amount of heat.

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 a 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 utilizes the heat of fusion at the melting point and the heat of solidification at the freezing point, and can store heat and dissipate heat with the phase change between the solid and the liquid.

The type of the latent heat storage material is not particularly limited, and can be selected from compounds having a melting point and capable of a 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. Aromatic hydrocarbons such as compounds and arylindan compounds; natural animal and vegetable oils such as camellia oil, soybean oil, corn oil, cottonseed oil, rapeseed oil, olive oil, palm oil, castor oil, and fish oil; mineral oil; diethyl ethers. And so on.

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 element temperature of the heating element, the temperature or holding temperature after cooling, the cooling method, and the like. ..
As the second heat storage material, a material having a phase change temperature (preferably melting point) in a target temperature region (for example, the operating temperature of the heating element; hereinafter also referred to as “heat control region”) 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 100 ° C, more preferably 10 to 70 ° C.

When the microcapsules contain the second heat storage material, the content of the second heat storage material is not particularly limited, but is preferably less than 30% by mass, more preferably less than 10% by mass, based on the total mass of the core. More preferably, it is 1% by mass or less. The lower limit is not particularly limited, but may be 0% by mass.
The total content of the aliphatic amine and the second heat storage material contained in the core is not particularly limited, but 80 to 100% by mass is preferable, and 90 to 100% by mass, based on the total mass of the core, in terms of better heat storage. More preferably by mass.

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

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 is out of the temperature range (heat control region; for example, the operating temperature of the heating element) in which the heat storage sheet is used. That is, the solvent refers to a solvent that does not undergo a phase change in the liquid state in the heat control region, and is distinguished from a heat storage material that causes a phase transition in the heat control region and causes an endothermic reaction.

Examples of the additives that can be included in the microcapsules as the core material include additives such as flame retardants, ultraviolet absorbers, light stabilizers, antioxidants, waxes, and odor suppressants.

The content of the solvent and the additive 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 may be 0% by mass.

<Physical characteristics>
The particle size of the core of the microcapsules is preferably 0.1 μm or more, more preferably 1 μm or more, still more preferably 5 μm or more, in that the amount of heat storage per unit volume is more excellent. The upper limit is not particularly limited, but is preferably 500 μm or less, more preferably 300 μm or less, still more preferably 120 μm or less, in that damage to the shell due to expansion due to the phase change of the core can be further suppressed.

The particle size of the core is an average value obtained by measuring the particle size of the core contained in any 20 microcapsules with an optical microscope or a transmission electron microscope (TEM).
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 is prepared, and the cross section is observed with an optical microscope or TEM at 100 to 5000 times, and "(value of median diameter based on volume of microcapsules) x 0.9 to (microcapsules). Select any 20 microcapsules with a particle size in the range of volume-based median diameter) × 1.1 ”and observe the cross section of each microcapsule to determine the particle size of the core and average it. By calculating the value, the particle size of the core of the microcapsules can be obtained.

[Shell (capsule wall)]
The microcapsules of the present invention have a shell containing a core, and the water vapor transmission rate of the shell is 10 ^-1 g / (m ² · day) or less.

By encapsulating the core using a shell having a water vapor transmission rate within a predetermined range, it is possible to suppress the denaturation of the aliphatic amine as the core material and suppress the deterioration of the heat storage amount per unit volume of the microcapsules over time. can.
The water vapor transmission rate of the shell is preferably ^10-2 g / (m ² · day) or less, and more preferably 10 ^-4 g / (m ² · day) or less, because the effect of the present invention is more excellent. The lower limit is not particularly limited, but ^10-5 g / (m ² · day) or more is preferable in that the amount of heat per unit volume is excellent and the cost is excellent because the shell does not become too thick.

In the present specification, the water vapor transmission rate (unit: g / (m ² · day)) of the shell constituting the microcapsules is described in JIS Z 0208, “Humidity Permeability Test Method for Moisture-Proof Packaging Material (Cup Method)”. It is a value measured based on. That is, the material (shell material) constituting the shell and the material (shell material) constituting the shell by a known method such as X-ray diffraction (XRD: X-ray diffraction) or X-ray photoelectron spectroscopy (XPS), if necessary. After analyzing and measuring the thickness of the shell, a layer having the same structure and thickness as the shell was formed on the substrate to prepare a test film, and the obtained test film was subjected to JIS Z 0208. The water vapor permeability (g / ( ^m2 · day)) of the shell can be obtained by performing the measurement according to the method described in “Heat Permeability Test Method for Moisture-Proof Packaging Material (Cup Method)”.

The method for forming the shell having a water vapor transmission rate of 10 ^-1 g / (m ² · day) or less is not particularly limited, and for example, a method for forming an inorganic layer made of an inorganic compound by a dry vapor deposition method described later may be used. Can be mentioned.

<Inorganic layer>
The structure of the shell is not particularly limited as long as it contains a core and satisfies the above-mentioned water vapor transmission rate, but the shell preferably has an inorganic layer made of an inorganic compound.
Examples of the inorganic compound constituting the inorganic layer include inorganic oxides, inorganic nitrides, and inorganic oxynitrides. Inorganic oxides or inorganic nitrides are preferable, and inorganic oxides are more preferable.
Examples of the inorganic compound include metal elements such as aluminum (Al), zirconia (Zr), hafnium (Hf), and titanium (Ti), as well as silicon (Si), boron (B), and germanium. Examples thereof include compounds containing at least one selected from the group consisting of metalloid elements such as (Ge), and compounds containing at least one element selected from the group consisting of Si, Al, Zr, Hf and Ti are preferable. ..

More specific inorganic compounds include inorganic oxides such as silicon oxide (silica), aluminum oxide (alumina), zirconium oxide (zirconia), hafnium oxide, titanium oxide (titania), and indium tin oxide (ITO). Examples thereof include silicon oxide, aluminum oxide, zirconium oxide, hafnium oxide, or titanium oxide, and aluminum oxide is more preferable.
The inorganic layer may contain the above-mentioned inorganic compound alone or in combination of two or more.

The method for forming the inorganic layer on the core can be selected from known dry vapor deposition methods such as physical vapor deposition (PVD) and chemical vapor deposition (CVD), depending on the inorganic material.
More specifically, sputtering, vacuum deposition, plasma CVD, and atomic layer deposition (ALD) can be mentioned.
Above all, it is preferable to form an inorganic layer on the core by the ALD method in that a dense film having high water vapor transmission rate can be formed even though the film thickness is thin.

The ALD method is a thin film forming technique utilizing a continuous chemical reaction of a gas phase, and is a kind of CVD. The ALD method is a film formation method in which a thin film is grown layer by layer at the atomic level by alternating active gas and reactive gas, which are also called precursors or precursors, by adsorption on the particle surface and subsequent chemical reaction. be.
The ALD method utilizes the so-called self-limiting effect, in which when the particle surface is covered with a certain gas, the adsorption of that gas does not occur anymore, and the unreacted precursor is adsorbed when only one layer is adsorbed. Exhaust. Subsequently, a reactive gas is introduced to oxidize or reduce the precursor to form only one thin film having a desired composition, and then the reactive gas is exhausted. By setting such a process as one cycle and repeating this cycle, the thin film of the molecular layer can be grown as many times as the number of repetitions.
Compared with other film forming methods, the ALD method has fewer film forming defects, can form a uniform film, and can form a film so as to follow the unevenness. Therefore, it is a pinhole. Defects can be significantly reduced.

As a device that can be used to form an inorganic layer on the core by the ALD method, after putting particles in the reaction vessel, the steps of introducing and exhausting the precursor gas and the reactive gas into the reaction vessel one after another are repeated. The device is not particularly limited as long as it can be used, and examples thereof include a barrel type ALD vacuum layer deposition device (manufactured by Creative Coatings Co., Ltd.). The device can form a film having a more uniform thickness by providing a barrel mechanism for stirring the particles introduced into the reaction vessel.

The precursor gas and the reactive gas used in the ALD method can be appropriately selected depending on the constituent material of the inorganic layer to be formed.
When the inorganic compound constituting the inorganic layer is at least one selected from the group consisting of silicon oxide, aluminum oxide, zirconium oxide, hafnium oxide, or titanium oxide, the precursor gas may be Si, Al, Zr, or the like. Examples thereof include organic compounds containing at least one selected from the group consisting of Hf and Ti, and examples of the reactive gas include oxide gases such as ozone and water vapor.

The shell may have only one inorganic layer, or may have two or more inorganic layers. When the shell has two or more inorganic layers, the two or more inorganic layers may be the same or different.
The thickness of the inorganic layer (total thickness when two or more layers are present) is not particularly limited, but from the viewpoint that the effect of the present invention is more stably exhibited, 3 nm or more is preferable, and 10 nm or more is more preferable. It is preferable, and more preferably 20 nm or more.
The upper limit of the thickness of the inorganic layer is not particularly limited, but is preferably 300 nm or less, more preferably 200 nm or less, in that cracks or cracks can be further suppressed.
The thickness of the inorganic layer may be measured according to a method for measuring the thickness (wall thickness) of the shell, which will be described later.

As the inorganic layer, it is preferable to form a dense inorganic layer in that the effect of the present invention and the amount of heat storage per unit volume of the microcapsules are well-balanced and excellent.

The shell may have a layer other than the above-mentioned inorganic layer.
Examples of the layer other than the inorganic layer include an organic layer made of an organic compound. As a more specific embodiment of the organic layer, a base layer which is formed inside the inorganic layer and has a function of flattening the formation surface of the inorganic layer, and a base layer formed outside the inorganic layer to protect the inorganic layer. Included is a protective layer that has the function of

The organic compound constituting the organic layer is not particularly limited, and known organic compounds can be used.
Examples of the organic compound include polyester, polyurethane, polyurea, polyurethane urea, melamine resin, acrylic resin, methacrylic resin, methacrylic acid-maleic acid copolymer, polystyrene, transparent fluororesin, polyimide, fluorinated polyimide, polyamide, and polyamideimide. , Polyetherimide, cellulose acylate, polyetheretherketone, polycarbonate, alicyclic polyolefin, polyarylate, polyethersulfone, polysulfone, fluorene ring-modified polycarbonate, alicyclic-modified polycarbonate, fluorene ring-modified polyester, acrylic compound, polysiloxane , And other organic silicon compounds. These may be used alone or in combination of two or more.

The method for forming the organic layer on the core is not particularly limited, and known methods can be mentioned.
For example, precursors such as monomers, dimers, trimmers and oligomers as organic compounds constituting the organic layer and additives such as polymerization initiators, silane coupling agents, surfactants and increasing viscosity agents are dissolved in an organic solvent. Then, this coating liquid is applied to the core, and after drying, the organic compound is polymerized or crosslinked by ultraviolet irradiation, electron beam irradiation and / or heating to form an organic layer on the core. Can be formed.

The thickness of the organic layer is not particularly limited, and is preferably 0.01 to 10 μm, more preferably 0.05 to 5 μm.
The shell may have only one organic layer or may have two or more organic layers. When the shell has two or more organic layers, the two or more organic layers may be the same or different.

The shell may have either the above-mentioned inorganic layer or the above-mentioned organic layer as long as the above-mentioned water vapor transmission rate is satisfied, but the shell has at least the above-mentioned inorganic layer in that the effect of the present invention is more excellent. Is preferable, and it is more preferable that the core and the inorganic layer are in direct contact with each other.
Above all, it is more preferable that the shell is composed of only an inorganic layer in that the effect of the present invention and the amount of heat per unit volume are well-balanced and excellent.

<Shell thickness (wall thickness)>
The thickness (wall thickness) of the shell of the microcapsules is not particularly limited as long as the above water vapor transmission rate is satisfied, but is preferably 5 nm or more, more preferably 10 nm or more, still more preferably 20 nm or more. The upper limit is not particularly limited, but 1 μm or less is preferable, 300 nm or less is more preferable, and 100 nm or less is further preferable, in that the content ratio of the contained core material is high and the amount of heat per unit volume is excellent.

The wall thickness is an average value obtained by measuring the individual wall thicknesses of any 20 microcapsules by TEM and averaging them.
Specifically, similarly to the above-mentioned method for measuring the particle size of the core, 20 microcapsules are selected from the observation images obtained by TEM, and the cross section of each microcapsule is observed to obtain the thickness of the shell. By calculating the average value, the wall thickness of the microcapsules can be obtained.

[Manufacturing method of microcapsules]
The microcapsules have, for example, a core preparation step of preparing a core containing an aliphatic amine and a shell forming step of forming a shell containing the core on the surface of the core.

The core preparation step is not particularly limited as long as it is a step of preparing a core for use in the shell forming step.
The aliphatic amine used as a raw material for the core may be a commercially available product. Examples of commercially available aliphatic amines include aliphatic diamines manufactured by Wako Pure Chemical Industries, Ltd., such as 1,6-diaminohexane, 1,8-diaminooctane and 1,10-diaminodecane.
Aliphatic amines are often in the form of particles or powders at room temperature. Therefore, in the core preparation step, a process of adjusting the particle size of the obtained aliphatic amine may be performed, if necessary. The above adjustment of the particle size may be performed by a known method of crushing and crushing the particles, and examples thereof include a method using a mortar and a pestle and a method using a crusher such as a bead mill, a roll mill and a ball mill.
When producing a core having a small particle size (for example, 10 μm or less), it is preferable to atomize the raw material particles using the above-mentioned pulverizer. In this case, the particle size of the core can be adjusted to a desired range by changing conditions such as the treatment time and the amount and size of beads added. Further, it is preferable to adjust the particle size of the core while measuring the particle size of the core using an apparatus such as an optical microscope or TEM.

Examples of the shell forming step include a method of forming an inorganic layer on the core described above and a method of forming an organic layer on the core, and at least a dry vapor deposition method is used to form an inorganic layer made of an inorganic compound. It is preferable to include a step. The details of these methods are as described above, and thus description thereof will be omitted here.

The core preparation step and the shell forming step are preferably carried out in an environment where the aliphatic amine contained in the core does not come into contact with water. As a result, denaturation of the aliphatic amine constituting the core can be suppressed, and a decrease in the amount of heat per unit volume of the microcapsules can be suppressed.
The above-mentioned "implemented in an environment where the aliphatic amine contained in the core does not come into contact with water" means that the core preparation step and the shell forming step do not substantially contain water in the core preparing step and the shell forming step. It means that it is carried out in an environment where the core and water do not come into direct contact with each other, such as an atmosphere of an inert gas. The above object is achieved by carrying out the core preparation step and the shell forming step under the above environment until a layer capable of preventing contact between the core and water, such as an inorganic layer described later, is formed.
Examples of the inert gas include nitrogen and noble gases such as helium and argon. The phrase "substantially free of water" from the inert gas means that the dew point of the inert gas is −40 ° C. or lower, and the dew point of the inert gas is preferably −40 ° C. or lower, preferably −60 ° C. The following are more preferred. The purity of the inert gas is preferably 99.9% by volume or more, more preferably 99.99% by volume or more.
In the core preparation step and the shell forming step, the nitrogen atmosphere has a dew point of −40 ° C. or lower (more preferably −60 ° C. or lower) and a purity of 99.9% by volume or more (more preferably 99.99% by volume or more). It is preferable to carry out below.

The core preparation step and the shell forming step are preferably performed at a melting point or lower from the viewpoint of suppressing denaturation of the aliphatic amine constituting the core.

[Physical characteristics of microcapsules]
The particle size of the microcapsules is not particularly limited, but the median diameter (Dm) based on the volume of the microcapsules is preferably 0.1 to 600 μm, more preferably 1 to 300 μm, still more preferably 5 to 150 μm.
When the microcapsule is used for an electronic component in the form of a heat storage member such as a heat storage sheet described later, the content of the microcapsule per unit volume can be further increased, and the heat storage amount per unit volume of the heat storage sheet or the heat storage member can be further improved. The particle size of the microcapsules is preferably 60 μm or less in terms of volume-based median diameter (Dm).

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 are obtained by immersing the heat storage sheet or the heat storage member in water or an organic solvent for 24 hours or more and centrifuging the obtained aqueous dispersion. Is obtained.

Regarding the ratio of the core in the microcapsules, the volume occupied by the core with respect to the total volume of the microcapsules is preferably 10% by volume or more, preferably 20% by volume or more, in that the amount of heat storage per unit volume of the microcapsules is more excellent. Is more preferable, 50% by volume or more is further preferable, and 90% by volume or more is particularly preferable. The upper limit is not particularly limited, but the volume occupied by the core with respect to the total volume of the microcapsules is 99.999 in that the strength of the shell is improved and the damage of the shell due to the expansion due to the phase change of the core can be further suppressed. It is preferably 99.99% by volume or less, more preferably 99.99% by volume or less.
It is preferable that the shell occupies the rest of the volume occupied by the core in the microcapsules.

The microcapsules are preferably mononuclear microcapsules.
The fact that the microcapsules are mononuclear means that there is substantially only one space in which the substance (core) contained in the microcapsules exists. The fact that there is substantially only one space in which the core exists means that one space (preferably a substantially spherical space) in the microcapsule, which is the largest space in which the core exists, is the core. 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 entire space in which. Further, it is preferable that the volume of the space having the largest volume (preferably a substantially spherical space) among the spaces in which the core exists is 10 times or more larger than the volume of the space having the second largest volume.
Further, the microcapsules are preferably substantially spherical.

[Heat storage sheet]
The heat storage sheet contains microcapsules containing an aliphatic amine. The heat storage sheet preferably contains the above microcapsules and a binder.
The heat storage sheet exhibits a heat storage function by transferring heat accompanying a phase change between a solid and a liquid of an aliphatic amine contained in microcapsules as a heat storage material. This makes it possible, for example, to absorb and release heat in a heating element that emits heat. When the heat storage sheet contains the above-mentioned microcapsules having an excellent heat storage amount per unit volume, it is possible to provide a heat storage sheet and a heat storage member (described later) that exhibit a more excellent heat storage function.

<Microcapsules>
The heat storage sheet contains 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.

<Binder>
The heat storage sheet preferably further contains a binder in terms of improving durability.
The binder is not particularly limited as long as it is a polymer having adhesion to microcapsules and capable of forming a desired shape such as a membrane, and examples thereof include water-soluble polymers and water-insoluble polymers.
The term "water-soluble" in the 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. A more suitable water-soluble polymer means that the dissolved amount is 10% by mass or more.
Further, "water-insoluble" in the water-insoluble 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-anhydrous. Maleic acid copolymer, isobutylene-maleic anhydride copolymer, polyvinylpyrrolidone, ethylene-acrylic acid copolymer, vinyl acetate-acrylic acid copolymer, carboxymethyl cellulose, methyl cellulose, casein, gelatin, starch derivative, gum arabic, And sodium alginate.
Examples of the water-insoluble polymer include silicone polymers such as silicone resin and silicone oil, acrylic resin, polyolefin, styrene-butadiene resin, polyurethane, polyurea, polyurethane urea, and PET (Polyethylene Terephthalate) resin.
Further, as the binder, the polymer having heat storage property described in International Publication No. 2018/207387 and JP-A-2007-031610 may be used, and the description of these documents is incorporated in the present specification.

It is preferable that the binder is plastically deformable at room temperature (25 ° C.) and has a function of exhibiting the properties of a plastic body in a heat storage sheet (or a heat storage body described later; the same applies hereinafter). When the heat storage sheet contains a binder that can be plastically deformed at room temperature and the above-mentioned microcapsules, the binder located between the microcapsules in the heat storage sheet is deformed by adhering or adhering to a plurality of microcapsules. Even when an external force is applied to the heat storage sheet for the above purpose, the microcapsules can be plastically deformed while maintaining the adhesion between the microcapsules, and the generation of voids such as cracks and cracks can be suppressed in the heat storage sheet.
Examples of such a binder include the above-mentioned silicone polymers, polyurethanes, polyureas, polyurethane ureas, acrylic resins, polyester resins, polyether resins, and polyolefin resins. Of these, high-viscosity silicone oil is preferable.
In addition, in this specification, "high viscosity" means that the viscosity of a polymer is 10,000 cP or more.
The viscosity of the polymer can be measured at 25 ° C. using an E-type viscometer (“RE-85U” manufactured by Toki Sangyo Co., Ltd.).

The content of the binder in the heat storage sheet is not particularly limited, but is preferably 0.1 to 30% by mass, more preferably 0.5 to 15% 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 other components other than the microcapsules and the 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 may be 0% by mass.
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, as the thermal conductivity of the heat conductive material, 50 Wm ^-1 K ^-1 or more is more preferable in terms of improving the heat dissipation of the heat storage sheet.
The thermal conductivity (unit: Wm ^-1 K ^-1 ) is a value measured by a flash method under 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.
For the thickness, the cut surface obtained by cutting the heat storage sheet in parallel with the thickness direction is observed by SEM, 5 arbitrary points are measured, and the average value of the thicknesses of the 5 points is taken as the average value.

(Latent heat capacity)
The latent heat capacity of the heat storage sheet is not particularly limited, but 150 J / cm ³ or more is preferable, and 180 J / cm ³ or more is more preferable, because the heat storage member has high heat storage property and is suitable for temperature control of the heat generating body that generates heat. , 200 J / cm ³ or more is more preferable. The upper limit is not particularly limited, but it is often 500 J / cm ³ or less.
The latent heat capacity is a value calculated from the heat storage amount 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 from the mass and volume of the sample. The mass of the sample is measured with an electronic balance. The volume of the sample is calculated by measuring the area and thickness with a caliper, a contact type thickness measuring machine, etc. when the sample is in the form of a sheet, and does not dissolve or swell when the sample is in the form of a lump. Obtained from the increased volume by immersing in a solvent (water, alcohol, etc.).

The heat storage sheet is preferably a plastic body that can be plastically deformed at room temperature (25 ° C.). That is, it is preferable that the heat storage sheet can be deformed by applying an external force in a room temperature environment. Such a heat storage sheet can be produced, for example, by incorporating the above binder together with microcapsules into the heat storage sheet.

<Manufacturing method of heat storage sheet>
The method for producing the heat storage sheet is not particularly limited, and examples thereof include known methods.
As a method for producing a heat storage sheet, for example, a coating liquid preparation step of mixing the above microcapsules, the above binder, and a solvent to prepare a coating liquid, and coating the obtained coating liquid on a substrate. A method having a coating step of forming a coating film and a drying step of drying the formed coating film can be mentioned.
As another method, there is also a method of producing a heat storage sheet by melt-forming a composition containing the above-mentioned microcapsules and the above-mentioned binder on a substrate.
If necessary, a single heat storage sheet can be manufactured by peeling the base material from the laminate of the 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 quickly dissipate heat from the heat generating portion to the heat storage portion to the base material, and it is preferable to add a heat conductive material such as a metal base material and a graphene sheet. A substrate made of a combination of and is more preferable.
The thickness of the base material is not particularly limited, but is preferably 1 to 1000 μm, more preferably 1 to 100 μm, still more preferably 1 to 25 μm.

It is preferable that the surface of the base material is 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 resin, 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.

The solvent used in the above-mentioned coating liquid preparation step is not particularly limited, and examples thereof include water such as ion-exchanged water and alcohol.
Examples of the coating method in the above coating step 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 in the above drying step is preferably 20 to 150 ° C, more preferably 30 to 120 ° C.
The drying time is preferably 30 seconds or longer, more preferably 1 minute or longer. Further, it is preferable that the drying step is completed immediately before all the solvents contained in the coating film are vaporized. There is no particular upper limit to the drying time, but from the viewpoint of the production efficiency of the heat storage sheet, the shorter the drying time, the more preferable.
In the drying step, the coating film may be flattened. Examples of the flattening treatment method include a method of improving the density of the aliphatic amine in the coating film by applying pressure to the coating film with a member such as a roller, a nip roller and a calendar.

<Use of heat storage sheet>
The heat storage sheet can be applied to various uses, for example, an electronic device (for example, a mobile phone (particularly a smartphone), a mobile information terminal, a personal computer (particularly a portable personal computer), a game machine, a remote control, etc.). Automotive (for example, batteries (particularly lithium ion batteries), control devices such as power ICs (Integrated Circuits), car navigation systems, liquid crystal monitors, LED (Light Emitting Diode) lamps, heat retention of canisters, etc.); Building materials suitable for temperature control during moderate temperature rise or indoor heating and cooling (for example, floor materials, roofing materials, wall materials, etc.); in response to changes in environmental temperature or changes in body temperature during exercise or rest. Clothes suitable for temperature control (for example, underwear, jackets, cold weather clothes, gloves, etc.); Air conditioners; Bedding; Exhaust heat utilization system that stores unnecessary exhaust heat and uses it as heat energy, etc. Can be done.
The above microcapsules can also be applied to these uses.

Above all, 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 the flow of air and a method of diffusing the heat to the entire housing of the electronic device by a heat pipe or a heat spreader are used. Has been done. 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 to 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 creates a portion in the electronic device where heat can be stored 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 composition, heat storage body]
The heat storage composition is a composition containing microcapsules containing an aliphatic amine.
The heat storage composition preferably contains the above microcapsules and the above binder.
The shape of the heat storage composition is not particularly limited, and may be a solid form (three-dimensional shape) such as a sheet shape, a film shape, a plate shape, a cylindrical shape, a spherical shape, and a lump shape. Further, the heat storage composition may be in an amorphous form having fluidity such as liquid or slurry. Hereinafter, the above solid heat storage composition is also referred to as a “heat storage body”.

The sheet-shaped, film-shaped or plate-shaped heat storage body is as described above in the above [heat storage sheet], including its preferred embodiment.
When the form of the heat storage body is not a sheet shape, a film shape, or a plate shape, the thickness of the heat storage body is preferably 0.5 mm or more, more preferably 1 mm or more, further preferably 2 mm or more, and particularly preferably 3 mm or more. .. The upper limit is not particularly limited, but is preferably 1000 mm or less, and more preferably 100 mm or less. The thickness means the shortest distance when the heat storage body is sandwiched between two parallel planes.
The components contained in the heat storage body, the physical properties of the heat storage body, and the use of the heat storage body may be the same as those already described for the heat storage sheet, including the preferred embodiments thereof.

The method for producing the heat storage composition and the heat storage body is not particularly limited. For example, a liquid heat storage composition (dispersion of microcapsules) can be prepared by mixing microcapsules containing an aliphatic amine as a heat storage material with optional components such as a binder and a solvent used as needed. Then, by drying the liquid heat storage composition, a solid heat storage composition (heat storage body) can be produced.

[Heat storage member]
The heat storage member has the above-mentioned heat storage sheet or heat storage body.
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 or the heat storage body in terms of handling.
Hereinafter, the heat storage member will be described using a heat storage sheet (sheet-shaped heat storage body) as an example.

<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 more preferable in that water resistance and flame retardancy are better.

As the protective layer, for example, a layer containing a known hard coat agent or a hard coat film described in JP-A-2018-202696, JP-A-2018-18387, and JP-A-2018-111793 may be used. good. Further, from the viewpoint of heat storage property, the protective layer having a polymer having heat storage property described in International Publication No. 2018/207387 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, colorants, 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, still more preferably 0.5 to 15 μm.
For the thickness, the cut surface obtained by cutting the protective layer in parallel with the thickness direction is observed by SEM, 5 arbitrary points are measured, and the average value of the thicknesses of the 5 points is taken as the average value.

The method of forming the protective layer is not particularly limited, and a known method 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 adhering the layers on the heat storage sheet can be mentioned.

<Adhesion layer>
An adhesion layer may be arranged for the purpose of improving the adhesion between the heating element and the heat storage sheet, which will be described later. 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. Further, as an 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, ultraviolet curable adhesive, and , Silicone adhesive and the like.
The acrylic pressure-sensitive adhesive refers to a pressure-sensitive adhesive containing a polymer of (meth) acrylic monomer ((meth) acrylic polymer).
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 composition containing an adhesive or 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 may further have a temporary base material. As a result, it is possible to suppress scratches on the heat storage sheet during storage and transportation of the heat storage member.
The specific example of the temporary base material is the same as the specific example of the base material. It is preferably a base material having a peeled surface.
When using the heat storage member, the temporary base material is peeled off from the heat storage member.

[Electronic device]
The electronic device has the above-mentioned heat storage member and a heating element.
The heat storage member (heat storage sheet or heat storage body, 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 "heat 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 under 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 has 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 a 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.

<Heat pipe, vapor chamber>
The electronic device preferably further comprises a heat transport member selected from the group consisting of heat pipes and vapor chambers.
Both the heat pipe and the vapor chamber are made of metal or the like and include at least a member having a hollow structure and a working fluid which is a heat transfer medium enclosed in the internal space thereof, and the working fluid in a high temperature part (evaporation part). Evaporates (vaporizes) and absorbs heat, and the vaporized working fluid condenses in the low temperature part (condensed part) and releases heat. The heat pipe and the vapor chamber have a function of transporting heat from a member in contact with a high temperature portion to a member in contact with a low temperature portion due to a phase change of the working fluid inside the heat pipe and the vapor chamber.

When the electronic device has a heat storage member and a heat transport member selected from the group consisting of a heat pipe and a vapor chamber, it is preferable that the heat storage member and the heat pipe or the vapor chamber are in contact with each other, and the heat storage member is a heat pipe. Alternatively, it is more preferable that the vapor chamber is in contact with the low temperature portion.
Further, when the electronic device has a heat storage member and a heat transport member selected from the group consisting of a heat pipe and a vapor chamber, the phase change temperature of the heat storage material contained in the heat storage sheet or the heat storage body of the heat storage member and the heat. It is preferable that the temperature range in which the pipe or vapor chamber operates overlaps. Examples of the temperature range in which the heat pipe or the vapor chamber operates include a range of temperatures at which the working fluid can undergo a phase change inside each of them.

The heat pipe has at least a tubular member and a working fluid enclosed in its internal space. The heat pipe preferably has a wick structure on the inner wall of the tubular member, which is a flow path for the working fluid based on the capillary phenomenon, and has an internal space inside the wick structure, which is a passage for the vaporized working fluid. .. Examples of the shape of the tubular member include a circular tubular, a square tubular, and a flat elliptical tubular. The tubular member may have a bent portion. Further, the heat pipe may be a loop heat pipe having a structure in which tubular members are connected in a loop shape.

The vapor chamber has at least a flat plate-shaped member having a hollow structure and a working fluid enclosed in the internal space thereof. The vapor chamber preferably has a wick structure similar to that of a heat pipe on the inner surface of a flat plate-shaped member. In the vapor chamber, heat is generally absorbed from a member in contact with one main surface of the flat plate-shaped member, and heat is released to the member in contact with the other main surface to transport heat.

The material constituting the heat pipe and the vapor chamber is not particularly limited as long as it is a material having high thermal conductivity, and examples thereof include metals such as copper and aluminum.
Examples of the working fluid enclosed in the internal space of the heat pipe and the vapor chamber include water, methanol, ethanol and CFC substitutes, which are appropriately selected and used according to the temperature range of the electronic device to be applied.

<Other members>
The electronic device may include a protective layer, a heat storage sheet or a heat storage body, a heat conductive material, a heating element, and a member 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.

The specific examples of the electronic device are as described above, so the description thereof will be omitted.

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

[Making microcapsules]
[Example 1]
The following steps were carried out to prepare the microcapsules of Example 1.
An isoparaffin-based solvent ("IP Solvent 1620", Idemitsu Kosan) in which water and oxygen are removed by bubbling treatment with dry nitrogen in a glove box filled with dry nitrogen (dew point -60 ° C or less, nitrogen concentration 99.99% by volume or more). A mixture was prepared by putting 1.5 g of (manufactured by Fuji Film Co., Ltd.), 0.3 g of 1,8-diaminooctane (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 0.5 g of zirconia beads having a diameter of 0.1 mmΦ into a cent tube. The mixture in the cent tube was shaken and stirred for 72 hours using a test tube mixer (“DeltaMixer Se-08”, manufactured by TAITEC). The scale of the test tube mixer was "5". The obtained mixed solution was decanted into a dispersion containing particles of 1,8-diaminooctane and zirconia beads. After removing the supernatant from the obtained dispersion by decantation, the particles were dried by directly spraying dry nitrogen for 3 hours to prepare core particles A1 composed of 1,8-diaminooctane.
The core particles A1 prepared above were placed in a vial filled with dry nitrogen, sealed, and then the vial was removed from the glove box.
From the observation image of the core particle A1 obtained by using a transmission electron microscope (TEM), it was confirmed that the particle size of the core particle A1 was 0.1 μm.

The obtained core particles A1 were placed in a barrel-type container of a barrel-type ALD vacuum film forming apparatus (manufactured by Creative Coatings Co., Ltd.). Next, the surface of the core particles A1 is coated with aluminum oxide (Al ₂ O ₃ ) by ALD in which the following operations (1) to (4) are sequentially performed at room temperature (25 ° C.) while rotating the container. Formed.
(1) A gas of trimethylaluminum as a precursor was introduced into the container at a flow rate of 3.0 sccm for 40 seconds. The unit "sccm" of the above flow rate means the flow rate (mL / min) of the gas converted into the value at 1 atm and 25 ° C.
(2) The residual gas in the container was exhausted by an exhaust pump.
(3) Activated steam was introduced into the container at a flow rate of 3.0 sccm for 60 seconds.
(4) The residual gas in the container was exhausted by an exhaust pump.
By repeating the above operations (1) to (4) as one cycle of ALD treatment step and repeating this ALD treatment step, a shell made of aluminum oxide (Al ₂ O ₃ ) having a thickness of 5 nm is provided, and 1,8 -The microcapsules of Example 1 containing the core particles A1 composed of diaminooctane were prepared. For the shell thickness (wall thickness), select any 20 microcapsules from the observation image obtained by TEM, observe the cross section of each microcapsule, obtain the shell thickness, and calculate the average value. It was measured by calculation.

[Examples 2 to 5]
From aluminum oxide (Al ₂ O ₃ ) according to the method described in Example 1, except that the number of cycles of the above ALD treatment step was adjusted so that the shell having the thickness shown in Table 1 described later was formed. Microcapsules of Examples 2 to 5 were prepared, which had a shell made of 1,8-diaminooctane and contained core particles A1.

[Examples 6 to 10]
When stirring the above mixture containing the isoparaffin solvent, 1,8-diaminooctane and zirconia beads using a test tube mixer, the stirring time is changed to 3 hours and the scale of the test tube mixer is changed to "3". Other than that, core particles A2 composed of 1,8-diaminooctane having a particle size of 5 μm were prepared according to the method described in Example 1. The particle size of the core particles A2 was measured using an optical microscope.
Example 1 except that the core particles A2 produced above were used and the number of cycles of the above ALD treatment step was adjusted so that a shell having the thickness shown in Table 1 described later was formed. In accordance with the method described in the above, microcapsules of Examples 6 to 10 having a shell made of aluminum oxide (Al ₂ O ₃ ) and containing core particles A2 made of 1,8-diaminooctane were prepared.

[Examples 11 to 35]
1,8-Diaminooctane (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) is crushed using a mortar and pestle in a glove box filled with dry nitrogen (dew point -60 ° C or lower, nitrogen concentration 99.99% by volume or more). As a result, core particles A3 to A7 composed of 1,8-diaminooctane having the particle diameters shown in Table 1 described later were prepared. The particle size of each core particle was measured using an optical microscope.
The number of cycles of the above ALD treatment step was adjusted so that any of the core particles A3 to A7 described in Table 1 described later was used and a shell having the thickness shown in Table 1 described later was formed. Other than that, according to the method described in Example 1, microcapsules of Examples 11 to 35 having a shell made of aluminum oxide (Al ₂ O ₃ ) and containing core particles made of 1,8-diaminooctane were prepared. Each was made.

[Example 36]
In a glove box filled with dry nitrogen (dew point -60 ° C or less, nitrogen concentration 99.99% by volume or more), 1,6-diaminohexane (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) is crushed using a mortar and pestle. As a result, core particles A8 made of 1,6-diaminohexane having a particle diameter of 50 μm were prepared. The particle size of the core particles A8 was measured using an optical microscope.
According to the method described in Example 1, except that the core particles A8 produced above were used and the number of cycles of the above ALD treatment step was adjusted so as to form a shell having a thickness of 50 nm. The microcapsules of Example 36 having a shell made of aluminum oxide (Al ₂ O ₃ ) and having a thickness of 50 nm and containing core particles A8 made of 1,6-diaminohexane were prepared.

[Example 37]
In a glove box filled with dry nitrogen (dew point -60 ° C or less, nitrogen concentration 99.99% by volume or more), 1,10-diaminodecane (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) is crushed using a mortar and pestle. As a result, core particles A9 made of 1,10-diaminodecane having a particle diameter of 50 μm were prepared. The particle size of the core particles A9 was measured using an optical microscope.
According to the method described in Example 1, except that the core particles A9 produced above were used and the number of cycles of the above ALD treatment step was adjusted so as to form a shell having a thickness of 50 nm. The microcapsules of Example 37 having a shell made of aluminum oxide (Al ₂ O ₃ ) and having a thickness of 50 nm and containing core particles A9 made of 1,10-diaminodecane were prepared.

[Examples 38 to 40]
The core particles A4 used in Examples 16 to 20 were used, trimethylsilane (SiO ₂ precursor) was used as a precursor in the operation (1) of the film forming step by ALD, and the thickness was 50 nm. A shell made of silicon oxide (SiO ₂ ) having a thickness of 50 nm is provided according to the method described in Example 1, except that the number of cycles of the ALD treatment step is adjusted so as to form a shell. Microcapsules of Example 38 containing core particles A4 composed of 8-diaminooctane were prepared.
Further, titanium oxide (TIM ₂ ) was according to the method described in Example 38, except that tripropyl orthotitanium (TiO ₂ precursor) was used as a precursor in the operation (1) of the film forming step by ALD. The microcapsules of Example 39 having a shell having a thickness of 50 nm and containing core particles A4 consisting of 1,8-diaminooctane were prepared.
Further, a thickness made of zirconia oxide (ZrO ₂ ) according to the method described in Example 38, except that trimethylzirconium (ZrO ₂ precursor) was used as a precursor in the operation (1) of the film forming step by ALD. The microcapsules of Example 40 having a shell having a zirconium of 50 nm and containing core particles A4 composed of 1,8-diaminooctane were prepared.

[Comparative Example 1]
20 parts by mass of 1,6-diaminohexane and 80 parts by mass of acrylic acid-maleic acid copolymer (acid value: 1044 mg / g · KOH, mass average molecular weight: 3000) manufactured by Aldrich Co., Ltd. are dissolved in 2250 parts by mass of water. , An aqueous solution (a) was obtained.
On the other hand, a non-polar solution (b) containing 1% by mass of sorbitan sesquioleate (manufactured by Tokyo Chemical Industry Co., Ltd.) as an emulsifier in 11250 parts by mass of an isoparaffin solvent (Isopar M, manufactured by ExxonMobil, boiling point 234 ° C.) as a non-polar medium. ) Was prepared.
This aqueous solution (a) was added to the non-polar solution (b), and the mixture was emulsified and dispersed by stirring at 5000 rpm using a homogenizer. Then, the obtained emulsion is heated and stirred at 80 ° C. for 24 hours at 350 rpm to remove water, whereby a primary capsule having an inner shell containing the above copolymer is dispersed on the surface of 1,6-diaminohexane. Obtained liquid.
After stirring the obtained dispersion at 40 ° C. for 3 hours, a solution prepared by dissolving 45 parts by mass of titanium tetrabutoxide (manufactured by Wako Pure Chemical Industries, Ltd.) in 1350 parts by mass of Isoper M as a monomer of an organic metal compound is a dispersion liquid. To obtain a dispersion of microcapsules in which titanium oxide (TiO ₂ ) was precipitated on the outermost layer. The obtained microcapsules were repeatedly washed with cyclohexane and then dried in a blower dryer at 40 ° C. to obtain microcapsules of Comparative Example 1. The microcapsules of Comparative Example 1 had core particles of 1,6-diaminohexane, an organic shell made of acrylic acid-maleic acid copolymer on the inside, and an inorganic shell made of titanium oxide (TiO ₂ ) on the outside. It has a structure arranged in order.
The thicknesses of the organic shell and the inorganic shell of the microcapsules of Comparative Example 1 were 50 μm and 0.1 μm, respectively, as a result of measurement by the method of cross-sectional observation using the TEM described in Example 1.

[Measurement and evaluation]
<Measurement of melting point of core material>
The melting point of the core material contained in the microcapsules obtained in the above Example or Comparative Example was measured using a differential scanning calorimeter (DSC) (product name "X-DSC7200", manufactured by Hitachi High-Tech Science Corporation). It was measured. The measurement conditions were a heating rate of 3 ° C./min and a temperature range of 20 to 100 ° C.

<Measurement of water vapor transmission rate>
The water vapor transmission rate (unit: g / (m ² · day)) of the shell constituting the microcapsules obtained in the above-mentioned Example or Comparative Example was determined by JIS Z 0208, “Humidity Permeability Test Method for Moisture-Proof Packaging Material (Cup”). The measurement was performed according to the method described in "Method)".
A PET film having a thickness of 100 μm is prepared, and a film is formed on one surface of the PET film according to the shell forming method described in each Example and Comparative Example to obtain a sample for measuring water vapor transmission rate. Made. The measurement sample prepared above and the PET film having no coating were left for 24 hours under the conditions of a temperature of 40 ° C. and 90% RH. The water vapor transmission rate (unit: g / ( ^m2 · day)) of each film was calculated from the mass change of the measurement sample and the PET film having no film before and after leaving. From the obtained calculated values of water vapor transmission rate, the water vapor transmission rate of the shell constituting the microcapsules of each Example or Comparative Example was evaluated based on the following evaluation criteria.

(Evaluation criteria)
A: 10 ^-4 g / (m ² · day) or less B: 10 ^-4 g / (m ² · day) over 10 ^-2 g / (m ² · day) or less C: 10 ^-2 g / (m ² )・ Day) Super 10 ^-1 g / (m ²・ day) or less D: 10 ^-1 g / (m ²・ day) Super

<Fresh heat storage amount>
Immediately after preparation in each Example or Comparative Example, the density (g / cm ³ ) of the microcapsules is measured using a dry automatic densitometer (product name "AccuPyc1330", manufactured by Shimadzu Corporation), and the unit mass is measured. The amount of heat stored per unit (J / g) is measured using a differential scanning calorimetry meter (DSC) (product name "X-DSC7200", manufactured by Hitachi High-Tech Science Co., Ltd.) at a temperature rise rate of 3 ° C./min and a temperature range. It was measured under the condition of 20 to 100 ° C.
From the obtained density (g / cm ³ ) and the heat storage amount per unit mass (J / g), the heat storage amount per unit volume (J / cm ³ ) of the microcapsules produced in each example was calculated.
From the calculated heat storage amount per unit volume (J / cm ³ ), the heat storage amount (Fresh heat storage amount) immediately after the production of the microcapsules was evaluated based on the following criteria.

(Evaluation criteria)
A: 350J / cm ³ or more B: 250J / cm ³ or more 350J / cm ³ or less C: 200J / cm ³ or more 250 (J / cm ³ ) or less D: 200J / cm ³ or less

<Evaluation of stability over time>
The microcapsules prepared in each Example and Comparative Example were subjected to a temporal stability test (accelerated test) in which they were left to stand for 12 hours in an atmosphere of 85 ° C. and 85% RH. After the test, the heat storage amount (J / cm ³ ) per unit volume of the microcapsules was calculated by the same method as the above <Fresh heat storage amount>.
For the microcapsules of each Example and Comparative Example, the ratio of the heat storage amount after the test (J / cm ³ ) to the heat storage amount immediately after production (J / cm ³ ) (heat storage amount after test / heat storage amount immediately after production) ( %) Was calculated.
From the calculated ratio (%), the stability over time regarding the amount of heat storage per unit volume of the microcapsules was evaluated based on the following criteria.

(Evaluation criteria)
A: More than 80% B: More than 50% 80% or less C: More than 20% 50% or less D: 20% or less

In addition, the appearance of 50 microcapsules arbitrarily selected from the microcapsules subjected to the above acceleration test was observed using an optical microscope or TEM. As a result, the number of microcapsules in which obvious cracks (cracks and gaps were formed) were observed in the shell was measured, and the durability (survival rate) of the microcapsules was evaluated based on the following criteria. did.

(Evaluation criteria)
A: More than 90% B: More than 50% 90% or less C: More than 30% 50% or less D: 30% or less

Table 1 shows the configurations and evaluation results of the microcapsules produced in Examples 1 to 40 and Comparative Example 1.
In Table 1, the "core material" column of "core particles" indicates the compounds contained as the core material in the microcapsules produced in each example.
The "melting point" column of "core particles" indicates the melting point (° C.) of the core material measured by the above method.
The "particle size" column of "core particles" indicates the particle size of the core particles measured by the above method.

In Table 1, the "Constituent material" column of "Shell" indicates the material constituting the shell in the microcapsules produced in each example, and the "Forming method" column indicates the shell forming method.
When the "Structure" column of "Shell" is "Inorganic shell", it means that the shell is composed of a single layer formed by the method shown in the "Formation method" column for the material shown in the "Constituent material" column. show. When the "Structure" column of "Shell" is "Organic shell / Inorganic shell", as described in Comparative Example 1, the shell is an organic shell made of an acrylic acid-maleic acid copolymer on the inside, and an organic shell made of an acrylic acid-maleic acid copolymer. It means that it consists of a two-layer structure of an inorganic shell made of titanium oxide (TiO ₂ ) on the outside.

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

Further, when the thickness of the shell is 10 nm or more, the stability of the heat storage amount per unit volume with time is more excellent, and when the thickness of the shell is 20 nm or more, the stability of the heat storage amount per unit volume with time is further improved. It was confirmed to be excellent (comparison of Examples 1 to 35).

It was confirmed that when the particle size of the core was 5 μm or more, the amount of heat storage per unit volume was more excellent (comparison of Examples 1 to 35).
Further, when the particle size of the core is 300 μm or less, the durability of the microcapsules after the time stability test is more excellent, and when the particle size of the core is 100 μm or less, the durability of the microcapsules after the time stability test is better. Was confirmed to be even better (comparison of Examples 1 to 35).

It was confirmed that when the number of carbon atoms of the aliphatic hydrocarbon group contained in the aliphatic amine is 8 or more, the heat storage amount per unit volume is more excellent (comparison of Examples 19, 36 and 37).

[Making a heat storage sheet]
The microcapsules (30 g) obtained in Examples 1-40 were added to a mixed solution of heptane (120 g) and isopropanol (30 g). Auridic WNN-153 (Acrylic resin manufactured by DIC Corporation) (3.1 g) was added to the obtained mixed solution as a binder to prepare a coating solution.
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.
A coating liquid is applied to the surface of the PET substrate on the adhesive layer side using a bar coater, and the obtained coating film is dried at 80 ° C. for 25 minutes to form a heat storage member having a thickness of 300 μm on the PET substrate. did. Then, the heat storage member was peeled off from the PET substrate to prepare a heat storage sheet.
As a result, it was confirmed that the heat storage sheet produced by using the microcapsules of the present invention is excellent in the stability of the heat storage amount over time.

Claims

A microcapsule having a core and a shell containing the core.
The core contains an aliphatic amine and
Microcapsules having a water vapor transmission rate of 10 -1 g / (m 2 · day) or less in the shell.
The microcapsule according to claim 1, wherein the shell has a water vapor transmission rate of 10-2 g / (m 2 · day) or less.
The microcapsule according to claim 1 or 2, wherein the aliphatic amine is an aliphatic polyamine having two or more amino groups.
The microcapsule according to any one of claims 1 to 3, wherein the aliphatic amine has a linear aliphatic hydrocarbon group having an even number of carbon atoms.
The microcapsule according to any one of claims 1 to 4, wherein the aliphatic amine has a linear aliphatic hydrocarbon group having an even number of 6 to 16 carbon atoms.
The microcapsule according to any one of claims 1 to 5, wherein the aliphatic amine has a melting point of 37 to 100 ° C.
The microcapsule according to any one of claims 1 to 6, wherein the shell has an inorganic layer made of an inorganic compound.
The microcapsule according to claim 7, wherein the core and the inorganic layer are in direct contact with each other.
The microcapsule according to claim 7 or 8, wherein the inorganic compound is an inorganic oxide.
The microcapsule according to any one of claims 7 to 9, wherein the inorganic compound is a compound containing at least one element selected from the group consisting of Si, Al, Zr, Hf and Ti.
The microcapsule according to any one of claims 1 to 10, wherein the shell has a thickness of 5 to 100 nm.
The microcapsule according to any one of claims 1 to 11, wherein the core has a particle size of 0.1 to 500 μm.
The method for producing microcapsules according to any one of claims 1 to 12.
A core preparation process for preparing a core containing an aliphatic amine,
It has a shell forming step of forming a shell containing the core on the surface of the core.
A method for producing microcapsules, wherein the core preparation step and the shell forming step are carried out in an environment where the aliphatic amine and water do not come into contact with each other.
The method for producing microcapsules according to claim 13, wherein the shell forming step is carried out in a nitrogen atmosphere having a dew point of −60 ° C. or lower and a purity of 99.9% by volume or more.
The method for producing microcapsules according to claim 13, wherein the shell forming step includes a step of forming an inorganic layer made of an inorganic compound by a dry vapor deposition method.
A heat storage sheet containing the microcapsules according to any one of claims 1 to 12 and a binder.
The method for manufacturing a heat storage sheet according to claim 16.
The step of mixing the microcapsules, the binder, and the solvent according to any one of claims 1 to 12 to prepare a coating liquid, and
The step of applying the coating liquid on the substrate to form a coating film, and
A method for manufacturing a heat storage sheet, which comprises a step of drying the coating film.
A heat storage body containing the microcapsules according to any one of claims 1 to 12 and a binder.