JP2017114965A - Capsule type heat storage material and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a capsule type heat storage material that prevents a capsule coating from breaking due to impact, or the volumetric change of a phase change material contained therein, and also inhibits the leakage of the phase change material.SOLUTION: A capsule type heat storage material has a core part having at least one phase change material, and a capsule wall containing the phase change material. The capsule wall has polycyanoacrylate, or polyurethane with an elongation of 5% or more.SELECTED DRAWING: None

Description

  The present invention relates to a capsule-type heat storage material and a method for producing the same.

Ice, normal paraffin, inorganic salts, and the like are known as latent heat storage materials for utilizing the latent heat generated with the phase change of substances (see Patent Document 1).
These latent heat storage materials have problems such as leakage to the outside when the phase change material is in a liquid state when using latent heat due to phase change between the liquid and solid of the phase change material. Therefore, in order to solve this problem, methods such as gelling or microencapsulating the phase change material or encapsulating the emulsified and dispersed phase change material with a hydrophilic polymer have been proposed (patents). Reference 2-6).

  On the other hand, as a method for producing a large-diameter capsule, Non-Patent Document 1 proposes a submerged curing coating method (a method for producing an artificial amount).

  Moreover, a capsule using a photocurable resin as a coating has been proposed (Patent Document 7).

JP 57-40582 A Japanese Patent Laid-Open No. 8-100191 JP-A-9-31452 JP 2002-69438 A JP 2001-303031 A JP 2007-145946 A International Publication No. 2009/128476

Kondo Yasu, Koishi Masumi, “New Microcapsules, Production, Properties, and Applications”, Sankyo Publishing Co., Ltd., November 1987, p. 38-40

  It is also conceivable to apply a submerged curing coating method described in Non-Patent Document 1 to increase the diameter of the capsule enclosing the phase change material. However, in the submerged curing coating method, it is necessary to quickly cure the coating resin after forming the capsule structure, and thus the usable coating resin is limited to a water-soluble resin or the like. Accordingly, there are problems such as low strength of the resin, poor water resistance of the resin, and easy leakage of the phase change material.

  Moreover, in the capsule of patent document 7, the film which has sufficient softness | flexibility may not be obtained. When the capsule coating is not sufficiently flexible, there is a problem that the phase change material leaks due to the coating being damaged by the volume change or impact of the phase change material that is the capsule contents.

  Therefore, an object of the embodiment of the present invention is to provide a capsule-type heat storage material that is less susceptible to damage to the capsule coating due to an impact or volume change of the phase change material contained therein, and less leaking of the phase change material.

  Embodiments of the present invention relate to the following capsule-type heat storage material and a method for manufacturing the capsule-type heat storage material.

  <1> A capsule including a core including at least one phase change material and a capsule wall including the phase change material, wherein the capsule wall includes polycyanoacrylate or polyurethane having an elongation of 5% or more. Type heat storage material.

  <2> The capsule-type heat storage material according to <1>, wherein the polyurethane having an elongation percentage of 5% or more is a polyurethane obtained by polymerizing a bifunctional to tetrafunctional urethane acrylate.

  <3> The capsule-type heat storage material according to <1> or <2>, wherein the capsule wall further contains a water-soluble resin.

  <4> The capsule wall includes an outer layer and an inner layer closer to the core than the outer layer, the outer layer includes polycyanoacrylate or polyurethane having an elongation of 5% or more, and the inner layer includes a water-soluble resin. <1> The capsule-type heat storage material described in 1.

  <5> The capsule-type heat storage material according to <1>, wherein the core portion further includes a water-soluble resin, and the phase-change material is dispersed in the water-soluble resin.

<6> A coating layer forming step of coating a core portion containing at least one phase change substance with an emulsion composition containing an aqueous polyurethane or urethane acrylate to form a coating layer, and a curing step of curing the coating layer,
A method for producing a capsule-type heat storage material.

  <7> The method for producing a capsule-type heat storage material according to <6>, further including a gelling step of gelling the coating layer, wherein the gelled coating layer is cured in the curing step.

  <8> The method for producing a capsule heat storage material according to <6> or <7>, wherein the emulsion composition further contains a water-soluble resin.

  According to the embodiment of the present invention, it is possible to provide a capsule-type heat storage material that is less likely to cause damage to the capsule coating (capsule wall) due to impact or volume change of the phase-change material to be included and that has little leakage of the phase-change material. it can.

1. Capsule type heat dissipation heat storage material A capsule type heat dissipation heat storage material according to an embodiment of the present invention includes a core portion including at least one phase change material, and a capsule wall containing the phase change material. A capsule-type heat storage material containing cyanoacrylate or polyurethane having an elongation percentage of 5% or more.

  When the capsule wall contains polycyanoacrylate, the strength of the capsule wall can be improved and the leakage of the phase change material can be reduced. In addition, when the capsule wall contains polyurethane having an elongation rate of 5% or more, the capsule wall can be made flexible, the leakage of the phase change material can be reduced, and the capsule strength can be improved. Can do.

In this specification, polycyanoacrylate is a polymer containing a structural unit derived from cyanoacrylate, and may be a homopolymer having only cyanoacrylate as a polymerization component. It may be a copolymer with the copolymer component.
One type of polycyanoacrylate may be used, or two or more types may be used in combination.

In the present specification, polyurethane is a polymer having a urethane bond (—NHCO—) in the repeating unit of the main chain.
The polyurethane having an elongation rate of 5% or more may be obtained by polymerizing urethane acrylate, for example. As the urethane acrylate, a 2- to 4-functional urethane acrylate is preferable.
When the urethane acrylate is bifunctional or higher, it is possible to obtain a polyurethane having excellent curability. When urethane acrylate is tetrafunctional or less, the crosslinking density can be lowered, and the flexibility of the obtained polyurethane can be increased.
Examples of bifunctional urethane acrylates include M-1200 manufactured by Toagosei Co., Ltd., EB8402 and EB270 manufactured by Daicel-Cytec Co., Ltd., and UV-3000B and UV-3500BA manufactured by Nippon Synthetic Chemical Industry Co., Ltd. Examples of UV-7510B and tetrafunctional urethane acrylate manufactured by Nippon Synthetic Chemical Industry Co., Ltd. include EB8405 and EB8210 manufactured by Daicel UCB Co., Ltd. and Beam Set EM-92 manufactured by Arakawa Chemical Industries, Ltd.

The elongation percentage of polyurethane is measured based on the following method.
A strip-shaped polyurethane test piece having a thickness of 80 μm to 100 μm and a width of 15 mm is prepared.
The prepared test piece was subjected to a tensile test with a strograph (product name: strograph VG, manufacturer: Toyo Seiki Seisakusho Co., Ltd.) (tensile speed: 10 mm / min), and the length before tension and the length at break were measured. Then, the elongation percentage is calculated based on the following formula.
Elongation rate (%) = (length at break-length before tension) / length before tension × 100

The elongation percentage of the polyurethane is preferably 5% or more, more preferably 10% or more, and further preferably 25% or more.
One type of polyurethane may be used, or two or more types (for example, a plurality of types having different elongation rates) may be used in combination.

It is preferable that the capsule wall further contains a water-soluble resin.
Examples of water-soluble resins include water-soluble polymers such as gelatin, gelatin derivatives, casein, agar, sodium alginate, starch, and polyvinyl alcohol.
One type of water-soluble resin may be used, or a plurality of types may be used in combination.

For example, in the embodiment, the capsule wall may contain polyurethane having a stretch rate of 5% or more and a water-soluble resin.
When the capsule wall includes polyurethane and a water-soluble resin, for example, it is preferable to include 5 to 30% by mass of the water-soluble resin with respect to the polyurethane. In addition, the quantity of water-soluble resin means the whole quantity as water-soluble resin before gelatinizing here, when water-soluble resin is gelatinized.

The capsule wall may have a multilayer structure including an outer layer and an inner layer closer to the core than the outer layer.
When the capsule wall has a multilayer structure, for example, the outer layer preferably contains polycyanoacrylate or polyurethane having an elongation of 5% or more, the inner layer preferably contains a water-soluble resin, the outer layer contains polycyanoacrylate, and the inner layer is water-soluble. More preferably, a functional resin is included. In the case of having an inner layer containing a water-soluble resin, it is easy to make the thickness of the capsule wall uniform, so that the phase change substance is difficult to leak.

It is also preferable that the core part further contains a water-soluble resin, and the phase change substance is dispersed in the water-soluble resin in the core part.
For example, the outer layer may include polycyanoacrylate, the core may include a water-soluble resin and at least one phase change material, and the phase change material may be dispersed in the water-soluble resin.
When the phase change substance is dispersed in the water-soluble resin, the content of the phase change substance can be increased, and as a result, the temperature maintenance time can be lengthened.
The core may further contain other components such as an emulsifier.

  In the present invention, examples of the phase change substance contained in the core include organic substances such as paraffin, fatty acid, and fatty acid derivative. Specifically, linear aliphatic hydrocarbons such as tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane, eicosan, heicosan and docosan, higher fatty acids such as lauric acid and myristic acid, or derivatives thereof (for example, methyl myristate) Fatty acid esters), aliphatic alcohols such as hexadecanol and stearyl alcohol, natural waxes, petroleum waxes and the like. Of these, normal paraffin is preferable.

The method for encapsulation is not particularly limited, but it is preferable to apply the production method of the present invention described later.
The outer diameter of the capsule is preferably 0.1 to 5 mm, more preferably 0.3 to 3 mm.

2. Method for Producing Capsule Type Heat Storage Material The method for producing a capsule type heat storage material according to an embodiment of the present invention is not particularly limited. For example, a core part containing at least one phase change material is coated with a coating layer composition. It can be produced by a method including a coating layer forming step for forming a coating layer and a curing step for curing the coating layer.
Note that in this specification, the term “process” is not limited to an independent process, and even if it cannot be clearly distinguished from other processes, the term “process” is used if the intended purpose of the process is achieved. included.
Below, each process is demonstrated and then the example of the method using an emulsion composition as a coating layer composition is demonstrated.

<Coating layer forming step>
In the coating layer forming step, the core layer including at least one phase change material is coated with the coating layer composition to form a coating layer.
A method for forming a coating layer by coating the core with a coating layer material is not particularly limited. For example, a double nozzle is used to form a core material containing at least one phase change substance from an inner nozzle. A method of feeding the coating layer composition from the outer nozzle and dropping it into water can be mentioned.

  Examples of the phase change material contained in the core include the phase change materials exemplified in the above-mentioned “1. Capsule type heat storage material”.

Examples of the component of the coating layer composition include a polymer, an oligomer, or a monomer such as polyurethane, urethane acrylate, or cyanoacrylate.
As the urethane acrylate, a 2- to 4-functional urethane acrylate is preferable. When the urethane acrylate is bifunctional or higher, it is possible to obtain a polyurethane having excellent curability, and when the urethane acrylate is tetrafunctional or lower, the crosslinking density can be lowered. Flexibility can be increased.

  As the polyurethane, for example, “reactive polyurethane” having an isocyanate group (—NCO group) as a reactive group at the terminal (or also referred to as “moisture-reactive polyurethane”) may be used. In the reactive polyurethane, when the isocyanate group reacts with moisture, carbamic acid and then an amine are generated, and the generated amine reacts with the isocyanate group of the reactive polyurethane to form a three-dimensional network structure. The polyurethane is cured.

  The coating layer composition may further contain other components such as a water-soluble resin and / or a polymerization initiator.

  There is no restriction | limiting in particular as water-soluble resin, What was illustrated in the above-mentioned "1. Capsule type heat storage material" can be used.

  When the coating layer composition contains a monomer or oligomer such as urethane acrylate or cyanoacrylate, the coating layer composition preferably further contains a polymerization initiator. There is no restriction | limiting in particular as a polymerization initiator, A normal thing can be used, for example, Irgacure 819 (bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide), Irgacure 184 (1-hydroxy). -Cyclohexyl-phenyl-ketone), Darocur 1173, Irgacure 907 (2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one), Irgacure 369 (2-benzyl-2- (dimethylamino) ) -1- (4-morpholinophenyl) -1-butanone), Irgacure 379 (2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone), Irgacure 2959 (1- [4- (2-hydroxyethoxy) -pheny ] -2-Hydroxy-2-methyl-1-propan-1-one) (above BASF), Kayacure DETX (2,4-diethylthioxanthen-9-one), Kayacure ITX (above Nippon Kayaku) Photopolymerization initiators such as lucillin TPO (diphenyl (2,4,6-trimethoxybenzoyl) phosphine oxide) (manufactured by BASF), benzophenone, acetophenone, 4-4′bisdiethylaminobenzophenone, benzyl, benzoin, benzoin ethyl ether Can be mentioned. These can be used alone or in combination of two or more.

  The coating layer composition may be, for example, in the form of an emulsion, as will be described later.

<Gelification process>
The coating layer may be gelled before being cured (gelation step). In this gelation step, for example, the surface of the coating layer is gelled. Thereby, leakage of the phase change material before the coating layer is cured can be prevented or reduced. Moreover, it is easy to maintain a capsule shape also when performing curing by heat in the curing step.

Although it does not specifically limit as a method of gelatinization, For example, the method of using the salt which produces | generates a multivalent ion is mentioned.
Examples of the method using a salt that generates a polyvalent ion include a method of dropping or immersing in an aqueous solution of a salt that generates a polyvalent ion. For example, in the coating layer forming step, a double nozzle is used to feed the core material containing at least one phase change substance from the inner nozzle and the coating layer composition is dropped from the outer nozzle to water. When using this method, there is a method of adding a salt that generates multivalent ions in water.
Examples of the multivalent ions include calcium ions and magnesium ions, and examples of the salts that generate the multivalent ions include calcium chloride, calcium nitrate, and magnesium sulfate.
The gelation step may be performed after the coating layer forming step. It is preferable that the gelation step is performed immediately after the coating layer forming step.

<Curing process>
In the curing step, the coating layer is cured to obtain a capsule wall.
For example, when a monomer or oligomer such as urethane acrylate or cyanoacrylate is contained in the coating layer composition, the monomer or oligomer may be polymerized in the curing step.

Examples of the method for curing the coating layer include curing with at least one selected from the group consisting of active energy rays, heat and moisture.
The active energy ray that can be used in the curing step is not particularly limited, and examples thereof include electromagnetic waves such as ultraviolet rays, X rays, and γ rays. Among these, ultraviolet rays are preferable. In that case, a high-pressure mercury lamp, a metal halide lamp, a xenon lamp, or the like can be preferably used as the light source.
Although it does not specifically limit as a method of hardening by heat, For example, the method of leaving at 60 degreeC or more, Preferably 70 degreeC or more, for example, 5 to 10 hours, Preferably it is 6 to 8 hours is mentioned.
The method of curing with moisture is not particularly limited, and examples thereof include a method of curing in water and a method of curing with moisture in the air. Although hardening time is not specifically limited, For example, 1 minute-60 minutes may be sufficient. Curing with moisture is preferably performed, for example, when the coating layer composition contains a compound having a reactive group that reacts in the presence of moisture (for example, a cyanoacrylate having a cyano group or a reactive polymer having an isocyanate group). Is called.

From the viewpoint of increasing the content of the phase change material in the capsule and extending the temperature maintenance time, it is preferable to perform curing by heat in the curing step. That is, when curing by heat, the capsule wall can be thinned by evaporating moisture, so the amount of phase change material in the capsule can be increased, and as a result, the temperature of the capsule-type heat storage material can be maintained. The time can be lengthened.
Moreover, it is preferable to gelatinize a coating layer by a gelatinization process before hardening by heat. When gelation is performed, the capsule shape can be maintained even when moisture is evaporated by heat curing.

  The curing method may be a combination of a plurality of types. For example, it may be a combination of heat and actinic radiation.

<Other processes>
When the capsule wall has a multilayer structure having an inner layer and an outer layer, for example, before the coating layer forming step, the core part is coated with a composition containing a water-soluble resin to form a water-soluble resin-containing layer. You may further have the process of gelling a resin content layer and obtaining an inner layer.

  Further, when the core portion includes a water-soluble resin and the phase change material is dispersed in the water-soluble resin, for example, before the coating layer forming step, at least one phase change material and the water-soluble resin A step of stirring the material of the core containing, forming an oil-in-water emulsion and gelling it may be further included. At this time, for example, the mixture of the phase change material and the water-soluble resin may further contain other components such as an emulsifier.

<Method for producing capsule-type heat storage material using emulsion composition>
An embodiment of a method for producing a capsule heat storage material will be described. In the following method, an emulsion composition containing water-based polyurethane or urethane acrylate is used as the coating layer composition in the capsule-type heat storage material manufacturing method.
That is, in the method for producing a capsule-type heat storage material of this embodiment, a coating layer is formed by coating a core portion containing at least one phase change material with an emulsion composition containing water-based polyurethane or urethane acrylate. And a curing step of curing the coating layer.

Examples of the aqueous polyurethane contained in the emulsion composition include self-dispersing polyurethane (for example, Superflex 460 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.).
The emulsion composition preferably further contains a water-soluble resin.
For example, it is preferable that the emulsion composition containing urethane acrylate further contains a water-soluble resin in the aqueous phase.
Moreover, the method of this embodiment further includes a gelling step of gelling the coating layer, and it is also preferable to cure the gelled coating layer in the curing step.
The coating layer forming step, the gelling step, the curing step, and the water-soluble resin are as described above.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

[Example 1]
5.0 g of urethane acrylate 1 (purple UV-3500BA, Nippon Synthetic Chemical Co., Ltd., oligomer, bifunctional) and 0.3 g of polymerization initiator 1 (Irgacure 907 (2-methyl-1- (4-methylthiophenyl)- 2-morpholinopropan-1-one) and BASF) were mixed to obtain a coating material mixture A1.
Hexadecane was fed from the inner nozzle of the double nozzle as a core material, and the coating material mixture A1 was fed from the outer nozzle and dropped into water. Immediately after the dropping, ultraviolet light was irradiated using “HANDY UV 500” (Oak Manufacturing Co., Ltd.) to obtain a capsule-type heat storage material of Example 1.

[Example 2]
A coating material mixture A2 was obtained by mixing 5.0 g of urethane acrylate 2 (purple UV-7510B, Nippon Synthetic Chemical Co., Ltd., oligomer, trifunctional) and 0.3 g of polymerization initiator 1.
From the inner nozzle of the double nozzle, hexadecane was fed as a phase change substance, and the coating material mixture A2 was fed from the outer nozzle and dropped into water. Immediately after the dropping, ultraviolet rays were irradiated using “HANDY UV 500” (Oak Manufacturing Co., Ltd.) to obtain a capsule-type heat storage material of Example 2.

[Examples 3 to 5]
Capsule types of Examples 3 to 5 are the same as Example 2 except that hexadecane used as a phase change material in the production of the capsule type heat storage material of Example 2 is changed to pentadecane, heptadecane, or methyl myristate, respectively. A heat storage material was obtained.

[Example 6]
From the inner nozzle of the double nozzle, hexadecane is fed as a phase change substance, and from the outer nozzle, an aqueous urethane resin emulsion (Superflex 460, Daiichi Kogyo Seiyaku Co., Ltd., Polymer) is fed as a coating material, and calcium chloride 10% by mass The film material was gelled by dropping into an aqueous solution. This capsule was allowed to stand at 70 ° C. for 6 hours to obtain a capsule-type heat storage material of Example 6.

[Examples 7 to 9]
Capsule types of Examples 7 to 9 are the same as Example 6 except that hexadecane used as a phase change substance in the production of the capsule type heat storage material of Example 6 is changed to pentadecane, heptadecane, or methyl myristate, respectively. A heat storage material was obtained.

[Example 10]
10.0 g of urethane acrylate emulsion (Beamset EM-92, Arakawa Chemical Co., Ltd., oligomer, tetrafunctional, nonvolatile content 40%), 7.0 g of 3.3% by weight aqueous solution of sodium alginate, and 0.3 g of polymerization Initiator 2 (Irgacure 2959 (1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one), BASF) was mixed to form a coating material mixture A3 Got.
Hexadecane was fed from the inner nozzle of the double nozzle as a phase change substance, and the coating material mixture A3 was fed from the outer nozzle and dropped into a 10% by mass calcium chloride aqueous solution to gel the coating material. The capsules were allowed to stand at 70 ° C. for 6 hours, and then irradiated with ultraviolet rays using “HANDY UV 500” (Oak Manufacturing Co., Ltd.) to obtain a capsule-type heat storage material of Example 10.

[Example 11]
A reactive polyurethane (PUR703, Sanyo Trading Co., Ltd., polymer), which is a film material, was fed in a heated and softened state to produce droplets. After injecting hexadecane as a phase change material into this droplet with a syringe, the droplet into which the phase change material was injected was dropped into water to obtain a capsule-type heat storage material of Example 11.

[Example 12]
A 3.3% by mass aqueous solution of sodium alginate cooled to below the melting point of hexadecane (phase change material) in advance was filled into a container, and hexadecane was injected as a phase change material from the bottom of the container to obtain a phase change material solidified into a spherical shape. . The spherical phase change material is taken out, coated with cyanoacrylate (Aron Alpha, Toa Gosei Co., Ltd., monomer), which is a film material, and left in a 50% humidity environment for 30 minutes. The capsule-type heat storage material of Example 12 is obtained. Obtained.

[Example 13]
As an inner layer material, a 3.3% by mass aqueous solution of sodium alginate that had been cooled to a melting point of hexadecane (phase change material) or less in advance was placed in a container. Hexadecane was injected as a phase change material from the lower part of the container to produce a phase change material solidified in a spherical shape. This spherically solidified phase change material was immersed in an aqueous calcium chloride solution (10% by mass) in a state of being coated with sodium alginate to gel the sodium alginate. This surface was coated with cyanoacrylate (Aron Alpha, Toa Gosei Co., Ltd., monomer), which is a film material, and allowed to stand in a 50% humidity environment for 30 minutes to obtain a capsule-type heat storage material of Example 13.

[Example 14]
While stirring a mixture of 37 g of 3.3% by weight aqueous solution of sodium alginate and 3 g of decaglyceryl monomyristate (DECAGLYN 1-M, Nikko Chemicals), 60 g of hexadecane as a phase change material was gradually added to the mixture. Then, an oil-in-water emulsion containing a water-soluble resin and a phase change substance as an oil phase was prepared. After the obtained emulsion was dropped into a 10% by weight aqueous solution of calcium chloride and gelled, the surface of the gelled product was coated with cyanoacrylate (Aron Alpha, Toagosei Co., Ltd., monomer) as a coating material, and humidity The capsule-type heat storage material of Example 14 was produced by leaving it in a 50% environment for 30 minutes.

[Comparative Example 1]
From the inner nozzle of the double nozzle, hexadecane is fed as a phase change substance, and from the outer nozzle, 3.3 mass% aqueous solution of sodium alginate is fed as a coating material, and dropped into a 10 mass% aqueous solution of calcium chloride, and the coating material is gelled. A capsule type heat storage material of Comparative Example 1 was obtained.

[Comparative Example 2]
A coating material mixture A4 was obtained by mixing 5.0 g of urethane acrylate 3 (purple UV7600B, Nippon Synthetic Chemical Co., Ltd., oligomer, hexafunctional) and 0.3 g of polymerization initiator 1.
From the inner nozzle of the double nozzle, hexadecane was fed as a phase change substance, and the coating material mixture A4 was fed from the outer nozzle and dropped into water. Immediately after the dropping, ultraviolet rays were irradiated using “HANDY UV 500” (Oak Manufacturing Co., Ltd.) to obtain a capsule-type heat storage material of Comparative Example 2.

[Evaluation]
The following evaluation was performed about the capsule-type heat storage material of the obtained Example and the comparative example. The results are shown in Tables 1-3.

(1) Polyurethane elongation (Examples 1 to 11 and Comparative Example 2)
<Preparation of polyurethane test piece>
For the measurement of polyurethane elongation in Examples 1 to 11 and Comparative Example 2, polyurethane test pieces prepared as described below were used.

Example 1
An applicator was set to a thickness of 100 μm, and a mixture in which the urethane acrylate 1 and the polymerization initiator 1 used in Example 1 were mixed at a mass ratio of 5: 0.3 on the PET film was applied. The coating layer was cured by irradiating with ultraviolet rays using “UV 500” (Oak Manufacturing Co., Ltd.). Thereafter, the PET film was peeled off to produce a strip-shaped polyurethane test piece having a thickness of 100 μm and a width of 15 mm.

(Examples 2 to 5)
Polyurethane test pieces of Examples 2 to 5 were produced in the same manner as the polyurethane test pieces of Example 1 except that the urethane acrylate 2 used in Examples 2 to 5 was used instead of the urethane acrylate 1.

(Examples 6 to 9)
An applicator was set so as to have a thickness of 200 μm, and the aqueous urethane resin emulsion used in Examples 6 to 9 was applied on a PET film and allowed to stand at 70 ° C. for 6 hours to cure the coating layer. Thereafter, the PET film was peeled off to produce a strip-shaped polyurethane test piece having a thickness of 80 μm and a width of 15 mm.

(Example 10)
An applicator was set so as to have a thickness of 200 μm, and a mixture in which the urethane acrylate emulsion 1 and the polymerization initiator 1 used in Example 10 were mixed at a mass ratio of 5: 0.3 was applied on the PET film. Was allowed to stand at 70 ° C. for 6 hours, and further, “HANDY UV 500” (Oak Manufacturing Co., Ltd.) was used to irradiate ultraviolet rays to cure the coating layer. Thereafter, the PET film was peeled off to produce a strip-shaped polyurethane test piece having a thickness of 80 μm and a width of 15 mm.

(Example 11)
An applicator was set to a thickness of 100 μm, and the reactive polyurethane 1 used in Example 11 was applied onto a PET film, and allowed to stand for 30 minutes in an environment of 50% humidity to be cured. Thereafter, the PET film was peeled off to produce a strip-shaped polyurethane test piece having a thickness of 80 μm and a width of 15 mm.

(Comparative Example 2)
A polyurethane test piece of Comparative Example 2 was prepared in the same manner as the preparation of the polyurethane test piece of Example 1 except that the urethane acrylate 3 used in Comparative Example 2 was used instead of the urethane acrylate 1.

<Measurement and calculation of elongation>
The produced polyurethane test piece was subjected to a tensile test with a strograph (product name: Strograph VG, manufacturer: Toyo Seiki Seisakusho Co., Ltd.) (tensile speed: 10 mm / min), and the elongation was calculated according to the following formula.
Elongation rate (%) = (length at break-length before tension) / length before tension × 100

(2) Capsule strength A 1 kg load was applied to the produced capsule-type heat storage material, and A was the one that did not break, and B was the one that the capsule was broken.

(3) Leakage The produced capsule-type heat storage material was left in a 35 ° C. environment and in a cycle environment (repeated to be left at −20 ° C. for 6 hours and then left at 35 ° C. for 6 hours: freeze-thaw test). Each was evaluated according to the following criteria. In the evaluation of leakage, A and B are in a practical range.

A: Leakage of the core material is not visually recognized, and even if it is brought into contact with plain paper. B: Leakage of the core material cannot be seen with visual observation, but it can be seen that the paper surface gets wet when contacted with plain paper.
C: The leakage of the core material can be visually confirmed.

(4) Temperature maintenance time The capsule-type heat storage material was allowed to stand in a −5 ° C. environment for 24 hours and then moved to a 35 ° C. environment and the temperature of the capsule-type heat storage material was measured with a thermocouple.
The time when the melting point (± 2 ° C.) of the core material was maintained was A for 5 minutes or more and B for less than 5 minutes.

(5) Phase change material / capsule volume ratio
After cleaving the capsule of the capsule-type heat storage material produced in each Example and Comparative Example, the cross section is observed with a microscope, and the volume of the capsule and the core is calculated from the capsule diameter and the core diameter, and the phase change material / Capsule volume ratio was calculated. For Example 14, the volume of the phase change material was calculated from the recipe.
A phase change material / capsule volume ratio of 40% or more was designated as A, and less than 40% was designated as B.

The capsule-type heat storage materials of Examples 1 to 5 and 11 become capsules with high capsule strength because the capsule wall (film) contains a flexible urethane resin (elongation rate of 5% or more), and freeze-thaw. It was possible to prevent leakage when left in a cycle environment where
Moreover, since the capsule-type heat storage material of Examples 6-9 is produced through curing by heat and includes a drying step, water in the film can be evaporated to thin the film (capsule wall). As a result, it can be seen that the content of the phase change material in the capsule can be increased and the temperature maintenance time can be increased.

  In Example 10, since a urethane acrylate emulsion is used as a film component, a water-soluble resin (sodium alginate in Example 10) can be added. Leakage before curing of the urethane resin due to gelation with the water-soluble resin. Can be prevented or reduced. Further, since drying is performed by heat, the capsule wall (film) can be thinned, and as a result, the content of phase change substances in the capsule content can be increased and the temperature maintenance time can be extended. I understand that.

  From the results of Examples 12 to 14, it can be seen that by using cyanoacrylate (that is, the obtained capsule wall (coating) contains polycyanoacrylate), the coating has high strength. In Example 12, the leakage evaluation is B even when left in a 35 ° C. environment, and a slight leakage of the phase change material is observed. This is considered to be caused by the non-uniform film thickness. On the other hand, in Example 13, it is easy to make the thickness of the film uniform by having the inner layer of the water-soluble resin. In Example 14, it can be seen that by dispersing the phase change material in the water-soluble resin, it is possible to increase the content of the phase change material and increase the temperature maintenance time.

On the other hand, the capsule-type heat storage material of Comparative Example 1 using only sodium alginate and hexadecane has a weak capsule strength, and when left in a 35 ° C. environment or in a cycle environment where freeze-thawing is repeated, There are also many leaks of phase change substances.
In the capsule-type heat storage material of Comparative Example 2 containing polyurethane having an elongation rate of less than 5%, there are many leakages of phase change substances when left in a cycle environment where freeze-thawing is repeated.

As described above, in Examples 1 to 14, it is possible to obtain a capsule-type heat storage material in which the capsule coating (capsule wall) is not easily damaged due to an impact or a volume change of the phase change substance to be included, and the phase change substance does not leak. I understand that.

Claims (8)

  Capsule type heat storage material comprising a core containing at least one phase change material and a capsule wall containing the phase change material, wherein the capsule wall contains polycyanoacrylate or polyurethane having an elongation of 5% or more .   The capsule-type heat storage material according to claim 1, wherein the polyurethane having an elongation percentage of 5% or more is a polyurethane obtained by polymerizing a 2- to 4-functional urethane acrylate.   The capsule-type heat storage material according to claim 1, wherein the capsule wall further contains a water-soluble resin.   The capsule wall includes an outer layer and an inner layer closer to the core than the outer layer, the outer layer includes polycyanoacrylate or polyurethane having an elongation of 5% or more, and the inner layer includes a water-soluble resin. Capsule type heat storage material.   The capsule-type heat storage material according to claim 1, wherein the core portion further includes a water-soluble resin, and the phase-change material is dispersed in the water-soluble resin. A coating layer forming step of forming a coating layer by coating a core containing at least one phase change material with an emulsion composition containing an aqueous polyurethane or urethane acrylate; and a curing step of curing the coating layer;
A method for producing a capsule-type heat storage material.   The method for producing a capsule-type heat storage material according to claim 6, further comprising a gelling step of gelling the coating layer, wherein the gelled coating layer is cured in the curing step.   The method for producing a capsule-type heat storage material according to claim 6 or 7, wherein the emulsion composition further contains a water-soluble resin.