Heat storage sheets, resin pellets, molded products

Abstract

The present invention addresses the problem of providing a thermal storage sheet having excellent conformability and heat resistance. The present invention further addresses the problem of providing a resin pellet and a molded article. The thermal storage sheet according to the present invention contains: microcapsules encapsulating a heat storage material; a first resin having an olefin-derived repeating unit and a hydrophilic group; and a second resin that is different from the first resin and that has an olefin-derived repeating unit. The capsule wall of the microcapsules contains at least one resin W selected from the group consisting of polyurethane urea, polyurethane, and polyurea.

Description

[Technical Field]

[0001] The present invention relates to a heat storage sheet, resin pellets, and a molded article. [Background Art]

[0002] While mobile devices such as smartphones and tablet PCs are compact, higher functionality and higher performance have been advancing, resulting in a significant increase in heat generation density. An increase in heat generation density accelerates thermal runaway or thermal cycle fatigue of solder. Therefore, in order to improve the reliability of mobile devices, countermeasures that address both the enhancement of thermal measures and the improvement of the strength reliability of solder joints are required.

[0003] As a method for suppressing heat generation from electronic components, passive cooling using a phase change material (PCM) has attracted attention in recent years. Since PCM can absorb heat via latent heat of fusion with almost no change in temperature, an effect of delaying the time required for a temperature increase, the so-called delay effect, can be obtained. As a member that contains PCM and has a function of storing heat generated externally, a heat storage body including microcapsules encapsulating a heat storage material such as paraffins is known. For example, Patent Document 1 discloses a resin pellet including microcapsules that encapsulate a heat storage material and have a capsule wall made of melamine resin. Patent Document 2 discloses a heat storage sheet in which microcapsules encapsulating a latent heat storage material in a resin outer shell are dispersed in a resin matrix. [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2019-137723 [Patent Document 2] International Publication No. WO 2017 / 221727 [Summary of the Invention] [Problems to be Solved by the Invention]

[0005] In electronic components, the increasing density of semiconductors in recent years has led to a growing problem of increased frequency of leakage current generation at high temperatures (e.g., above 80°C). Furthermore, repeated exposure of electronic components such as CPUs and image sensors to high-temperature environments can cause cracks to form at the joints of different materials, such as ceramics, resins, and metals, due to differences in material expansion and contraction. Moreover, prolonged exposure of electronic components to high-temperature environments can accelerate the degradation of electronic materials. To prevent these issues, electronic components are equipped with functions to suppress temperature increases by controlling processing speed or cutting off power supply. However, these functions can lead to operational delays due to reduced processing speed in PCs or game consoles, or limitations on recording time during video recording in cameras.

[0006] The present inventors evaluated the characteristics of a heat storage body manufactured with reference to Patent Documents 1 and 2, and found that there is room for further improvement in the heat storage body's conformability and heat resistance. If the heat storage material has poor conformability, when applying it to an object with a curved or uneven surface (e.g., grooves), such as an electronic component, a gap may form between the heat storage material and the surface shape of the object, preventing the heat storage material from fully exhibiting its heat absorption function. Furthermore, if the heat storage material has low heat resistance, it may deform when exposed to high-temperature environments for extended periods. As a result, gaps may form between the material and the surface of the object, leading to reduced adhesion.

[0007] In view of the above circumstances, the present invention aims to provide a heat storage sheet with excellent conformability and heat resistance. Furthermore, the present invention aims to provide resin pellets and molded articles. [Means for solving the problem]

[0008] As a result of diligent study on the above problems, the inventors of this invention have found that the above problems can be solved by the following configuration.

[0009] [1] A heat storage sheet comprising microcapsules containing a heat storage material, a first resin having repeating units derived from olefins and having hydrophilic groups, and a second resin different from the first resin having repeating units derived from olefins, wherein the capsule walls of the microcapsules contain at least one resin W selected from the group consisting of polyurethane urea, polyurethane, and polyurea. [2] The heat storage sheet according to [1], wherein the repeating units derived from olefin in the first resin include repeating units derived from ethylene, and the repeating units derived from olefin in the second resin include repeating units derived from ethylene, or the repeating units derived from olefin in the first resin include repeating units derived from propylene, and the repeating units derived from olefin in the second resin include repeating units derived from propylene. [3] The heat storage sheet according to [1], wherein the repeating units derived from olefin in the first resin include repeating units derived from propylene, and the repeating units derived from olefin in the second resin include repeating units derived from propylene. [4] The heat storage sheet according to any one of [1] to [3], wherein the hydrophilic group is at least one group selected from the group consisting of a carboxyl group, a carboxylic anhydride group, a hydroxyl group, and an amino group. [5] A heat storage sheet as described in any of [1] to [4], wherein the thickness of the sheet is 200 μm or more. [6] A heat storage sheet according to any of [1] to [5], wherein the melting point of the heat storage material is 50 to 95°C. [7] A heat storage sheet according to any one of [1] to [6], wherein the amount of the heat storage material is 15% by mass or more of the total mass of the heat storage sheet. [8] An extruded heat storage sheet as described in any of [1] to [7]. [9] The heat storage sheet according to any one of [1] to [8], wherein the content of the second resin is 15% by mass or more relative to the total mass of the heat storage sheet.

[10] A heat storage sheet according to any of [1] to [9], wherein the content of the second resin is greater than the content of the first resin.

[11] The heat storage sheet according to any one of [1] to

[10] , wherein the resin W has a polymethylene polyphenylene structure.

[12] A resin pellet comprising a microcapsule containing a heat storage material, a first resin having repeating units derived from olefins and having hydrophilic groups, and a second resin different from the first resin having repeating units derived from olefins, wherein the capsule wall of the microcapsule contains at least one resin W selected from the group consisting of polyurethane urea, polyurethane, and polyurea.

[13] The resin pellet according to

[12] , wherein the hydrophilic group is at least one group selected from the group consisting of a carboxyl group, a carboxylic anhydride group, a hydroxyl group, and an amino group.

[14] The resin pellets described in

[12] or

[13] , wherein the heat storage material has a melting point of 50 to 95°C.

[15] A resin pellet according to any one of

[12] to

[14] , wherein the content of the heat storage material is 15% by mass or more of the total mass of the resin pellet.

[16] The resin pellet according to any one of

[12] to

[15] , wherein the second resin is a thermoplastic resin and the content of the thermoplastic resin is 15% by mass or more relative to the resin pellet.

[17] A resin pellet according to any of

[12] to

[16] , wherein the content of the second resin is greater than the content of the first resin.

[18] A molded article comprising microcapsules containing a heat storage material, a first resin having repeating units derived from olefins and having hydrophilic groups, and a second resin different from the first resin having repeating units derived from olefins, wherein the capsule walls of the microcapsules contain at least one resin W selected from the group consisting of polyurethane urea, polyurethane, and polyurea. [Effects of the Invention]

[0010] According to the present invention, a heat storage sheet with excellent conformability and heat resistance can be provided. Furthermore, according to the present invention, resin pellets and molded articles can also be provided. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram of a portion of an image obtained by observing a cross-section of a heat storage sheet with a scanning electron microscope. [Modes for carrying out the invention]

[0012] In this specification, a numerical range represented by "~" means a range that includes the numbers written before and after "~" as the lower and upper limits, respectively. In the numerical ranges described stepwise in this specification, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described stepwise. Furthermore, in the numerical ranges described in this specification, the upper or lower limit stated in one numerical range may be replaced with the values ​​shown in the examples. The various components described later may be used individually or in combination of two or more. For example, the resin described later may be used individually or in combination of two or more. In this specification, the amount of each component in a composition, layer, or mixture means the total amount of any multiple substances present in the composition, layer, or mixture, unless otherwise specified, if there are multiple substances corresponding to that component.

[0013] In this specification, "repeating unit" is a general term for atomic groups derived from a single monomer molecule directly formed by the polymerization of monomers, and atomic groups obtained by chemically transforming a portion of the above atomic group. In this specification, (meth)acrylic refers to acrylic and methacrylic. In this specification, "preparation" includes not only the act of preparing specific materials by synthesis and / or mixing, but also the act of procuring specified items by purchase, etc. In this specification, "room temperature" means 25°C unless otherwise specified. In this specification, when referring to values ​​that may vary with temperature, unless otherwise specified, those values ​​are those at 25°C. In this specification, a combination of two or more preferred embodiments is a more preferred embodiment.

[0014] The following describes an example of an embodiment for carrying out the present invention. The present invention is not limited to the following embodiments and can be implemented with various modifications within the scope of its gist.

[0015] [Heat storage sheet] The heat storage sheet of the present invention (hereinafter also referred to as "this heat storage sheet") comprises microcapsules containing a heat storage material, a first resin having repeating units derived from olefins and having hydrophilic groups, and a second resin different from the first resin, which also has repeating units derived from olefins. Furthermore, the capsule walls of the microcapsules contain at least one resin W selected from the group consisting of polyurethane urea, polyurethane, and polyurea.

[0016] This heat storage sheet exhibits its heat storage function through the exchange of heat between the heat storage material encapsulated in microcapsules, and absorbs and releases heat from heat-generating elements. In particular, this heat storage sheet has excellent conformability, so it deforms to follow the surface shape of electronic components, adhering tightly to them without gaps and allowing the heat storage material to fully exert its heat absorption function. Furthermore, because this heat storage sheet has excellent heat resistance, deformation is less likely to occur even when used in high-temperature environments, and a decrease in adhesion to the surface of the object can be suppressed. Based on the above, this heat storage sheet can further improve the heat absorption function when applied to objects such as electronic components.

[0017] Features of the heat storage sheet of the present invention include the inclusion of a combination comprising microcapsules having capsule walls containing a predetermined resin W, a predetermined first resin, and a predetermined second resin. Although the detailed mechanism by which the conformability and heat resistance of the heat storage sheet can be improved by selecting the above combination of resins is unknown, the inventors speculate that the excellent compatibility of the resin W forming the capsule wall of the microcapsules, a predetermined first resin, and a predetermined second resin allows the microcapsules to be uniformly arranged in the heat storage sheet, thereby improving the conformability of the heat storage sheet. Furthermore, because the first and second resins have excellent heat resistance, the shape and function of the heat storage sheet are maintained even in high-temperature environments.

[0018] The following details each component contained in this heat storage sheet. In this specification, the superior conformability and / or heat resistance of the object will also be described as "excellent effects of the present invention."

[0019] [Microcapsules] A microcapsule has a core portion and a capsule wall for enclosing the core material (also called the encapsulated substance or encapsulated component) that makes up the core portion. Microcapsules contain a heat storage material as a core material (encapsulated component). Because the heat storage material is encapsulated within the microcapsules, it can stably exist in a phase state corresponding to the temperature.

[0020] <Heat storage material> The type of heat storage material is not particularly limited, and a material that undergoes a phase change in response to temperature changes can be used. A material that can repeatedly undergo a solid-liquid phase change accompanied by a state change between melting and solidifying in response to temperature changes is preferred. The phase change of the heat storage material is preferably based on the phase change temperature of the heat storage material itself, and in the case of a phase change between solid and liquid phases, it is preferably based on the melting point.

[0021] The heat storage material can be any of the following: a material that can store heat generated outside the heat storage sheet as sensible heat, a material that can store heat generated outside the heat storage sheet as latent heat (hereinafter also referred to as "latent heat storage material"), or a material that undergoes a phase change due to a reversible chemical change. The heat storage material is preferably one that can release the stored heat. In particular, latent heat storage materials are preferred as heat storage materials in terms of ease of controlling the amount of heat that can be transferred and the magnitude of the heat that can be transferred.

[0022] A latent heat storage material is a material that stores heat generated outside the heat storage sheet 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 that can exchange heat through latent heat by repeatedly undergoing a change between melting and solidifying, with the melting point determined by the material being the phase change temperature. Latent heat storage materials, in the case of a phase change between solid and liquid phases, utilize the heat of fusion at the melting point and the heat of solidification at the freezing point to store and release heat along with the phase change between solid and liquid.

[0023] The type of latent heat storage material is not particularly limited and can be selected from compounds that have a melting point and are capable of phase change. Examples of latent heat storage materials include ice (water); inorganic salts; aliphatic hydrocarbons such as paraffin (e.g., isoparaffin, normal paraffin); fatty acid ester compounds such as tri(caprylic / capric acid) glyceryl, methyl myristate (melting point 16-19°C), isopropyl myristate (melting point 167°C), and dibutyl phthalate (melting point -35°C); alkylnaphthalene compounds such as diisopropylnaphthalene (melting point 67-70°C), and 1-phenyl-1-xylylethane (melting point less than -50°C). Examples include diarylalkane compounds, alkylbiphenyl compounds such as 4-isopropylbiphenyl (melting point 11°C), triarylmethane compounds, alkylbenzene compounds, benzylnaphthalene compounds, diarylalkylene compounds, and arylindan compounds; aromatic hydrocarbons; natural animal and vegetable oils such as camellia oil, soybean oil, corn oil, cottonseed oil, rapeseed oil, olive oil, coconut oil, castor oil, and fish oil; mineral oils; diethyl ethers; aliphatic diols; sugars; sugar alcohols, etc.

[0024] The phase change temperature of the heat storage material is not particularly limited and can be appropriately selected depending on the type of heat-generating element, the heat-generating temperature of the element, the temperature after cooling or the holding temperature, and the cooling method. It is preferable to select a heat storage material that has a phase change temperature (preferably its melting point) within the target temperature range (for example, the operating temperature of the heating element; hereinafter also referred to as the "thermal control range"). The phase change temperature (melting point) of the heat storage material varies depending on the thermal control region, and may be, for example, 0 to 100°C, preferably 10 to 100°C, and more preferably 30 to 100°C. Among these, 50 to 95°C is even more preferable, 60 to 95°C is particularly preferable, and 65 to 95°C is most preferable, as it provides superior heat storage capabilities for controlling the heat quantity of a heat-generating element or utilizing heat in a high-temperature environment.

[0025] In terms of superior heat storage capacity of the heat storage sheet, aliphatic hydrocarbons are preferred as latent heat storage materials, and paraffin is more preferred. The melting point of the aliphatic hydrocarbon (preferably paraffin) is not particularly limited and is suitable for various applications. For example, it is 0°C or higher, preferably 10°C or higher, and more preferably 30°C or higher. For applications in high-temperature environments such as electronic components, it is even more preferable to have a melting point of 50°C or higher, particularly preferable to have a melting point of 60°C or higher, and most preferably 65°C or higher. There is no particular upper limit, but it is preferably 100°C or lower, more preferably 95°C or lower, and even more preferably 90°C or lower. As for aliphatic hydrocarbons, linear aliphatic hydrocarbons are preferred because they provide superior heat storage capacity for the heat storage sheet. The number of carbon atoms in linear aliphatic hydrocarbons is not particularly limited, but 18 or more is preferred, 23 or more is more preferred, 26 or more is even more preferred, and 28 or more is particularly preferred. There is no particular upper limit, but 60 or less is preferred, and 52 or less is more preferred. The content of linear aliphatic hydrocarbons is preferably 50 to 100% by mass, more preferably 70 to 100% by mass, even more preferably 80 to 100% by mass, and particularly preferably 90 to 100% by mass, relative to the content of the heat storage material. Furthermore, the content of linear aliphatic hydrocarbons is preferably 80 to 100% by mass, more preferably 90 to 100% by mass, and even more preferably 95 to 100% by mass, relative to the content of paraffin.

[0026] Examples of linear aliphatic hydrocarbons (linear paraffins) with a melting point above 0°C include n-tetradecane (C14 H 30 , melting point: 6°C), n-pentadecane (C 15 H 32 , melting point: 10°C), n-hexadecane (C 16 H 34 , melting point: 18°C), n-heptadecane (C 17 H 36 , melting point: 22°C), n-octadecane (C 18 H 38 , melting point: 28°C), n-nonadecane (C 19 H 40 , melting point: 32°C), n-eicosane (C 20 H 42 , melting point: 37°C), n-henicosane (C 21 H 44 , melting point: 40°C), n-docosane (C 22 H 46 , melting point: 44°C), n-tricosane (C 23 H 48 , melting point: 48 to 50°C), n-tetracosane (C 24 H 50 , melting point: 52°C), n-pentacosane (C 25 H 52 , melting point: 53 to 56°C), n-hexacosane (C 26 H 54 , melting point: 57°C), n-heptacosane (C 27 H 56 , melting point: 60°C), n-octacosane (C 28 H 58 , melting point: 62°C), n-nonacosane (C 29 H 60 , melting point: 63 to 66°C), n-triacontane (C 30 H 62 , melting point: 66°C), hentriacontane (C 31 H 64 , melting point: 68°C), dotriacontane (C 32 H 66 , melting point: 69°C), tritriacontane (C 33 H 68 , melting point: 71°C), n-tetratriacontane (C 34 H 70 , melting point: 73°C), pentatriacontane (C 35 H 72(melting point 75℃), n-hexatriacontane (C 36 H 74 (melting point 77°C), heptatriacontane (C) 37 H 76 , melting point 78℃) and n-octatricontane (C 38 H 78 Examples include a melting point of 78°C.

[0027] When using paraffin as a heat storage material, one type of paraffin may be used alone, or two or more types may be mixed together. When using multiple paraffins with different melting points, the temperature range in which heat storage properties are exhibited can be broadened.

[0028] When using multiple paraffins, the content of the main paraffin is not particularly limited in terms of the temperature range in which heat storage properties are exhibited and the amount of heat stored, but 50 to 100% by mass is preferred, 70 to 100% by mass is more preferred, 70 to 100% by mass is even more preferred, and 90 to 100% by mass is particularly preferred, relative to the total mass of paraffins. The term "primary paraffin" refers to the paraffin that is present in the largest quantity among the various paraffins contained. The primary paraffin content is preferably 50% by mass or more of the total paraffin mass. Furthermore, while the paraffin content is not particularly limited, it is preferably 80 to 100% by mass, more preferably 90 to 100% by mass, even more preferably 95 to 100% by mass, and particularly preferably 98 to 100% by mass, relative to the total mass of the heat storage material (preferably latent heat storage material).

[0029] As inorganic salts, inorganic hydrated salts are preferred, and examples include alkali metal chloride hydrates (e.g., sodium chloride dihydrate), alkali metal acetate hydrates (e.g., sodium acetate hydrate), alkali metal sulfate hydrates (e.g., sodium sulfate hydrate), alkali metal thiosulfate hydrates (e.g., sodium thiosulfate hydrate), alkaline earth metal sulfate hydrates (e.g., calcium sulfate hydrate), and alkaline earth metal chloride hydrates (e.g., calcium chloride hydrate). Examples of aliphatic diols include 1,6-hexanediol and 1,8-octanediol. Examples of sugars and sugar alcohols include xylitol, erythritol, galactitol, and dihydroxyacetone.

[0030] The heat storage material may be used alone or in a mixture of two or more types. By using one type of heat storage material or multiple materials with different melting points, the temperature range in which heat storage is exhibited and the amount of heat stored can be adjusted according to the application. By mixing a heat storage material with a melting point at the desired core temperature, and other heat storage materials with melting points before and after it, the temperature range over which heat can be stored can be broadened. To explain this specifically using paraffin as a heat storage material, if paraffin a, which has a melting point at the desired core temperature, is used as the core material, and paraffin a is mixed with other paraffins that have carbon atoms before and after paraffin a, the heat storage sheet can be designed to have a wide temperature range (thermal control range).

[0031] The amount of heat storage material contained in the heat storage sheet is not particularly limited, for example, 5% by mass or more relative to the total mass of the heat storage sheet. In particular, for superior heat storage performance, 15% by mass or more is preferred, 20% by mass or more is more preferred, 32% by mass or more is even more preferred, and 40% by mass or more is especially preferred, relative to the total mass of the heat storage sheet. There is no particular upper limit; for example, it is 80% by mass or less of the total mass of the heat storage sheet, and preferably 70% by mass or less.

[0032] The amount of heat storage material in the microcapsules is not particularly limited, but in terms of superior heat storage performance, it is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more, relative to the total mass of the microcapsules. While there is no particular upper limit, a percentage of 95% by mass or less is preferred, more preferably 85% by mass or less, and even more preferably 70% by mass or less, in terms of the durability and heat resistance of the microcapsules, and in particular, in terms of suppressing the bleeding (leakage) of the heat storage material when the heat storage sheet is exposed to a high-temperature environment.

[0033] (Other core materials) The microcapsules may contain other components besides the heat storage material described above as core materials. Examples of other components that can be contained in the microcapsules as core materials include additives such as solvents, ultraviolet absorbers, light stabilizers, antioxidants, waxes, odor suppressants, and flame retardants. The amount of heat storage material in the core material is not particularly limited, but 80 to 100% by mass and 90 to 100% by mass are preferred, and more preferably, of the total mass of the core material, in terms of providing superior heat storage performance for the heat storage sheet.

[0034] The microcapsules may contain a solvent as a core material. In this case, the solvent refers to the aforementioned heat storage material whose melting point falls outside the temperature range in which the heat storage sheet is used (thermal control range; for example, the operating temperature of the heat-generating element). In other words, the solvent refers to a substance that does not undergo a phase change in a liquid state within the thermal control range, and is distinguished from heat storage materials that undergo a phase transition and undergo heat absorption / release reactions within the thermal control range. The solvent content in the core material is not particularly limited, but is preferably less than 30% by mass, more preferably less than 10% by mass, and even more preferably 1% by mass or less, relative to the total mass of the core material. The lower limit is not particularly limited, but 0% by mass is an example.

[0035] <Capsule wall (wall section)> Microcapsules have a capsule wall that encloses a core material. The capsule wall of the microcapsule contains at least one resin W selected from the group consisting of polyurethane urea, polyurethane, and polyurea. Polyurethane is a polymer having multiple urethane bonds, and the reaction product of polyol and polyisocyanate is preferred. Furthermore, polyurea is a polymer having multiple urea bonds, and the reaction product of polyamine and polyisocyanate is preferred. Furthermore, polyurethane urea is a polymer having urethane bonds and urea bonds, and is preferably a reaction product of a polyol, a polyamine, and a polyisocyanate, or a reaction product of a polyol and a polyisocyanate. Furthermore, when polyurethane urea is obtained by reacting a polyol with a polyisocyanate, a portion of the polyisocyanate reacts with water to form a polyamine, which then yields the polyurethane urea.

[0036] The capsule walls of the microcapsules preferably have urethane bonds. Capsule walls having urethane bonds can be obtained, for example, using the polyurethane urea or polyurethane described above.

[0037] Polyurethane, polyurea, and polyurethane urea are preferably formed using polyisocyanate.

[0038] Polyisocyanates are compounds having two or more isocyanate groups, and include aromatic polyisocyanates and aliphatic polyisocyanates. Examples of aromatic polyisocyanates include m-phenylenediisocyanate, p-phenylenediisocyanate, 2,6-tolylenediisocyanate, 2,4-tolylenediisocyanate, naphthalene-1,4-diisocyanate, diphenylmethane-4,4'-diisocyanate, 3,3'-dimethoxy-biphenyldiisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, xylylene-1,4-diisocyanate, xylylene-1,3-diisocyanate, 4-chloroxylylene-1,3-diisocyanate, 2-methylxylylene-1,3-diisocyanate, 4,4'-diphenylpropanediisocyanate, and 4,4'-diphenylhexafluoropropanediisocyanate.

[0039] Examples of aliphatic polyisocyanates include trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-1,3-diisocyanate, cyclohexylene-1,4-diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,4-bis(isocyanate-methyl)cyclohexane, 1,3-bis(isocyanate-methyl)cyclohexane, isophorone diisocyanate, lysine diisocyanate, and hydrogenated xylylene diisocyanate.

[0040] While the above examples include bifunctional aromatic polyisocyanates and aliphatic polyisocyanates, polyisocyanates can also include those with three or more functions (for example, trifunctional triisocyanates and tetrafunctional tetraisocyanates). More specifically, examples of polyisocyanates include biuret or isocyanurate compounds, which are trimers of the above-mentioned bifunctional polyisocyanates; adducts (compounds) of polyols such as trimethylolpropane and bifunctional polyisocyanates; formalin condensates of benzene isocyanates; polyisocyanates having polymerizable groups such as methacryloyloxyethyl isocyanate; and lysine triisocyanate. Polyisocyanates are described in the "Polyurethane Resin Handbook" (edited by Keiji Iwata, published by Nikkan Kogyo Shimbun (1987)).

[0041] Among these, polyisocyanates with three or more functionalities are preferred. Examples of polyisocyanates with three or more functions include aromatic polyisocyanates with three or more functions, and aliphatic polyisocyanates with three or more functions. Specific examples of polyisocyanates with three or more functions include trimethylolpropane adducts of polyisocyanates such as 2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate, and hexamethylene diisocyanate (e.g., "Barnock® D-750" manufactured by DIC Corporation), as well as trimers (biuret or isocyanurate) of the above-mentioned bifunctional polyisocyanates. The polyisocyanates described in paragraph

[0038] of International Publication No. 2020 / 110662 are also examples.

[0042] Furthermore, polymethylene polyphenyl polyisocyanate is also preferred as the polyisocyanate. As the polymethylene polyphenyl polyisocyanate, the compound represented by formula (X) is preferred.

[0043] [ka]

[0044] In equation (X), n represents the number of repeating units. The number of repeating units n is, for example, an integer of 1 or more, preferably an integer between 1 and 10, and more preferably an integer between 1 and 5.

[0045] Examples of polyisocyanates containing polymethylene polyphenyl polyisocyanate include Myrionate® MR-100, MR-200, MR-400 (manufactured by Tosoh Corporation); WANNATE® PM-200, PM-400 (manufactured by Manka Japan Co., Ltd.); Cosmonate® M-50, M-100, M-200, M-300 (manufactured by Mitsui Chemicals, Inc.); and Boranate® M-595 (manufactured by Dow Chemical Company Limited).

[0046] Polyols are compounds having two or more hydroxyl groups, and examples include low molecular weight polyols (e.g., aliphatic polyols, aromatic polyols), polyether polyols, polyester polyols, polylactone polyols, castor oil polyols, polyolefin polyols, and hydroxyl group-containing amine compounds. Low molecular weight polyols refer to polyols with a molecular weight of 500 or less. Examples include bifunctional low molecular weight polyols such as ethylene glycol, diethylene glycol, and propylene glycol, as well as trifunctional or more low molecular weight polyols such as glycerin, trimethylolpropane, hexanetriol, pentaerythritol, and sorbitol. In terms of improving heat resistance, low molecular weight polyols are preferred as the above polyol, trifunctional or more low molecular weight polyols are more preferred, and trifunctional low molecular weight polyols are even more preferred.

[0047] Examples of hydroxyl group-containing amine compounds include amino alcohols, such as oxyalkylated derivatives of amino compounds. Examples of amino alcohols include N,N,N',N'-tetrakis[2-hydroxypropyl]ethylenediamine and N,N,N',N'-tetrakis[2-hydroxyethyl]ethylenediamine, which are propylene oxide or ethylene oxide adducts of amino compounds such as ethylenediamine.

[0048] Polyamines are compounds having two or more amino groups (primary or secondary amino groups), and include aliphatic polyhydric amines such as diethylenetriamine, triethylenetetramine, 1,3-propylenediamine, tetraethylenepentamine, and hexamethylenediamine; epoxy compound adducts of aliphatic polyhydric amines; alicyclic polyhydric amines such as piperazine; and heterocyclic diamines such as 3,9-bis-aminopropyl-2,4,8,10-tetraoxaspiro-(5,5)undecane. In terms of improving the heat resistance of the resin, low molecular weight polyamines are preferred as the polyamines, trifunctional or higher low molecular weight polyamines are more preferred, and trifunctional to tetrafunctional low molecular weight polyamines are even more preferred. Low molecular weight polyamines refer to polyamines with a molecular weight of 500 or less.

[0049] In particular, the resin W contained in the capsule wall preferably has a polymethylene polyphenyl structure, as this can further suppress the bleeding of the heat storage material when the heat storage sheet is exposed to a high-temperature environment. An example of a polymethylene polyphenyl structure is the structure represented by the following formula (Y). The structure represented by formula (Y) corresponds to the structure contained in the resin obtained when the compound represented by the above-mentioned formula (X) is used as a raw material for polyisocyanate.

[0050] [ka]

[0051] In formula (Y), n represents the number of repeating units. The number of repeating units n is, for example, an integer of 1 or more, preferably an integer between 1 and 10, and more preferably an integer between 1 and 5.

[0052] In particular, resin W is preferably a resin obtained by reacting an aromatic or alicyclic diisocyanate with a compound having three or more active hydrogen groups in one molecule (hereinafter also simply referred to as "polyisocyanate A") and polymethylene polyphenyl polyisocyanate (hereinafter also simply referred to as "polyisocyanate B"), in order to further suppress the bleeding of the heat storage material when the heat storage sheet is exposed to a high-temperature environment. Of the aromatic or aliphatic diisocyanates mentioned above, aromatic diisocyanates are preferred from the viewpoint of heat resistance. Furthermore, as compounds having three or more active hydrogen groups in one molecule, polyols are preferred, and low molecular weight polyols are more preferred.

[0053] When polyisocyanate A and polyisocyanate B are used in combination, the mass ratio of polyisocyanate A to polyisocyanate B (mass of polyisocyanate A / mass of polyisocyanate B) is not particularly limited, but 98 / 2 to 10 / 90 is preferred, 80 / 20 to 10 / 90 is more preferred, and 50 / 50 to 20 / 80 is even more preferred.

[0054] While there are no particular limitations on the content of the capsule wall in the microcapsules, it is preferable that the content is 5 to 60% by mass, more preferably 15 to 60% by mass, and even more preferably 30 to 55% by mass, based on the total mass of the microcapsules, in order to achieve a good balance between the heat storage properties of the heat storage sheet and the effect of suppressing the bleeding of the heat storage material when the heat storage sheet is exposed to a high-temperature environment.

[0055] (Physical properties of microcapsules) The particle size of the microcapsules is not particularly limited, but the median diameter (Dm) of the microcapsules based on volume is preferably 1 to 500 μm, more preferably 1 to 200 μm, even more preferably 1 to 100 μm, and particularly preferably 2 to 50 μm. Smaller microcapsule sizes result in a better appearance of the heat storage sheet. Furthermore, while there are no particular limitations on the average inner diameter of the microcapsules, it is preferably 200 μm or less, more preferably 1 to 100 μm, and even more preferably 2 to 50 μm. The inner diameter of the microcapsule refers to the diameter of the core portion. The particle size and inner diameter of the microcapsules can be controlled by changing the dispersion conditions in the emulsification process, which will be described later in the microcapsule manufacturing method section.

[0056] The average particle size and average inner diameter of microcapsules are measured by the following method. First, a cross-sectional section of the heat storage sheet or resin pellet is prepared, and the cross-section is observed at 1000x magnification using a scanning electron microscope (SEM). Figure 1 shows a schematic diagram of a portion of the image obtained by observing the cross-section of the heat storage sheet with an SEM. In the SEM image of the cross-section of the heat storage sheet 13 shown in Figure 1, the inside of the microcapsule 10 (inclusions 10b), the capsule wall 10a, and the outer region of the microcapsule (resin 12) are observed separately. The particle size and inner diameter of up to 20 microcapsules 10 present in the observed field of view are measured in order from the largest microcapsule 10, and the average value is obtained by arithmetic mean. If the number of microcapsules 10 present in the above field of view is less than 20, the particle size and inner diameter of all microcapsules are measured, and the average value is obtained by arithmetic mean. This operation is performed in 5 fields of view, and the average of the average values ​​obtained at each location is calculated to obtain the average particle size and average inner diameter of the microcapsules. The inner diameter measured above is the longest inner diameter observed when viewing the microcapsule.

[0057] The thickness of the capsule wall of the microcapsule is not particularly limited, but is preferably 10.00 μm or less, more preferably 5.00 μm or less, and even more preferably 2.00 μm or less, as this provides superior heat storage performance for the heat storage sheet. On the other hand, a certain thickness is preferable, more preferably 0.10 μm or more, and even more preferably 0.2 μm or more, as this suppresses bleeding of the heat storage material when the heat storage sheet is exposed to a high-temperature environment and maintains the strength of the capsule wall. The wall thickness refers to the average value obtained by measuring the individual wall thickness (μm) of any 20 microcapsules using a scanning electron microscope (SEM) and averaging the resulting measurements. Specifically, cross-sectional sections of a heat storage sheet or resin pellet are prepared, and the cross-sections are observed using a scanning electron microscope (SEM). Twenty microcapsules are selected from those with a particle size of ±10% of the particle size calculated using the measurement method described above. The wall thickness of each of these selected microcapsules is measured by observing its cross-section, and the arithmetic mean is calculated by adding the 20 measured values ​​together to determine the wall thickness of the microcapsule.

[0058] When the particle size of the microcapsule described above is Dm [unit: μm] and the thickness of the capsule wall of the microcapsule described above is δ [unit: μm], the ratio of the thickness of the capsule wall of the microcapsule to the particle size of the microcapsule (δ / Dm) is preferably 0.300 or less, more preferably 0.200 or less, and even more preferably 0.100 or less. The lower limit of δ / Dm is preferably 0.001 or higher, more preferably 0.005 or higher, and even more preferably 0.010 or higher, in order to maintain the strength of the microcapsules.

[0059] The glass transition temperature of the capsule wall of a microcapsule is not particularly limited, but it is preferable that it is 150°C or higher, or that the capsule wall does not exhibit a glass transition temperature. In other words, it is preferable that the glass transition temperature of the material constituting the capsule wall of the microcapsule is 150°C or higher, or that the material constituting the capsule wall of the microcapsule does not exhibit a glass transition temperature. Furthermore, if the capsule wall of the microcapsule exhibits a glass transition temperature, that temperature is preferably 160°C or higher, more preferably 180°C or higher, and even more preferably 200°C or higher, in terms of superior heat resistance. When the capsule wall of the microcapsule exhibits a glass transition temperature, there is no particular upper limit to that temperature, but it is often below the thermal decomposition temperature of the capsule wall of the microcapsule, and is generally 250°C or lower. In particular, it is preferable that the capsule wall of the microcapsule does not exhibit a glass transition temperature, as this provides superior heat resistance.

[0060] Furthermore, the statement that the capsule wall of a microcapsule does not exhibit a glass transition temperature means that the capsule wall of the microcapsule (the material constituting the capsule wall of the microcapsule) does not exhibit a glass transition temperature from 25°C to a temperature obtained by subtracting 5°C from the thermal decomposition temperature of the capsule wall (thermal decomposition temperature - 5°C), as described later. In other words, it means that the glass transition temperature is not observed in the range from "25°C" to "(thermal decomposition temperature (°C) - 5°C)". The glass transition temperature of the capsule wall of a microcapsule is 150°C or higher, or the method for preventing the capsule wall from exhibiting a glass transition temperature is not particularly limited and can be adjusted by appropriately selecting the raw materials used in the manufacture of the microcapsule. For example, since polyurea exhibits a high glass transition temperature, one method is to construct the capsule wall from polyurea. Another method is to increase the crosslinking density in the material constituting the capsule wall. Furthermore, another method is to introduce aromatic ring groups (for example, benzene ring groups found in a polymethylene-polyphenylene structure) into the material constituting the capsule wall.

[0061] The following methods can be used to measure the glass transition temperature of the capsule wall of a microcapsule. For example, ethyl acetate is placed in powdered microcapsules before melting and kneading, and the mixture is stirred at 25°C for 24 hours. Then, the resulting solution is filtered, and the resulting residue is vacuum-dried at 60°C for 48 hours to obtain microcapsules that contain nothing inside (hereinafter simply referred to as "measurement material"). In other words, the capsule wall material of the microcapsules, which is the target of glass transition temperature measurement, is obtained. Next, the thermal decomposition temperature of the obtained material is measured using a thermogravimetric differential thermal analyzer (TG-DTA) (instrument name: DTG-60, Shimadzu Corporation). The thermal decomposition temperature is defined as the temperature at which the mass of the material is reduced by 5% by mass compared to the mass of the material before heating, when the material is heated from room temperature at a constant heating rate (10°C / min) in a thermogravimetric analysis (TGA) in an atmospheric environment. Next, the glass transition temperature of the material to be measured is measured using a differential scanning calorimeter (DSC-60a Plus, Shimadzu Corporation) in a sealed pan at a heating rate of 5°C / min in the range of 25°C to (thermal decomposition temperature (°C) - 5°C). The glass transition temperature of the microcapsule wall is taken from the value obtained during the second heating cycle.

[0062] The thermal decomposition temperature of the microcapsule wall is not particularly limited, but it is preferably 200°C or higher, more preferably 220°C or higher, and even more preferably 230°C or higher, as this provides superior heat resistance. The thermal decomposition temperature of the capsule wall refers to the temperature at which the capsule wall is reduced by 5% by mass. One measurement method is to use the thermogravimetric differential thermal analyzer TG-DTA (instrument name: DTG-60, Shimadzu Corporation), which is used when measuring the glass transition temperature as described above.

[0063] The content of microcapsules in the heat storage sheet is not particularly limited, and the content of the heat storage material is adjusted to fall within the range described above. More specifically, the microcapsule content is preferably 20 to 90% by mass, more preferably 30 to 80% by mass, even more preferably 40 to 75% by mass, and particularly preferably 45 to 70% by mass, relative to the total mass of the heat storage sheet, in order to provide a good balance between the heat storage capacity and conformability of the heat storage sheet. Generally, increasing the microcapsule content in a heat storage sheet improves its heat storage capacity. However, if the microcapsule content increases too much, the sheet's conformability decreases. As a result, the degree of adhesion to the object may decrease, and the improved heat absorption function may not be properly utilized. In contrast, this heat storage sheet has excellent conformability, so even with a higher microcapsule content, it can conform to the object to which it is applied and fully utilize its heat absorption function.

[0064] (Method of manufacturing microcapsules) The method for manufacturing microcapsules is not particularly limited, and known methods can be used. For example, an interfacial polymerization method can be described as comprising the steps of: preparing an emulsion by dispersing an oil phase containing at least a heat storage material and a capsule wall material in an aqueous phase containing at least an emulsifier (emulsification step); and forming a capsule wall and a microcapsule by polymerizing the capsule wall material at the interface between the oil phase and the aqueous phase (encapsulation step). Furthermore, the term "capsule wall material" refers to a material capable of forming a capsule wall. The capsule wall material contains at least the above-mentioned compounds that serve as raw materials for resin W. For details of each step of the interfacial polymerization method, please refer to paragraphs

[0051] to

[0057] of International Publication No. 2020 / 110662, the contents of which are incorporated herein by reference.

[0065] [First resin] This heat storage sheet contains a first resin having repeating units derived from olefin and having hydrophilic groups. Olefins are aliphatic hydrocarbons having at least one ethylenically unsaturated group. Preferably, olefins consist of aliphatic hydrocarbons having at least one ethylenically unsaturated group. The olefin may be an α-olefin (a linear or branched aliphatic hydrocarbon having one ethylenically unsaturated group at one terminal), a β-olefin, or a γ-olefin (a linear or branched aliphatic hydrocarbon having one ethylenically unsaturated group at a non-terminal position), with α-olefins or β-olefins being preferred, and α-olefins being more preferred. The number of carbon atoms in the olefin is, for example, 2 to 10, preferably 2 to 6, and more preferably 2 to 4. The olefins mentioned above are preferably ethylene, propylene, i-butene, or n-butene, with ethylene or propylene being more preferred.

[0066] Examples of hydrophilic groups contained in the first resin include hydroxyl groups, amino groups, alkylamino groups, alkoxy groups, aryloxy groups, cyano groups, nitro groups, acylamino groups, arylamino groups, ureido groups, sulfamoylamino groups, alkylthio groups, arylthio groups, alkoxycarbonylamino groups, sulfonamide groups, carbamoyl groups, sulfamoyl groups, sulfonyl groups, alkoxycarbonyl groups, heterocyclic oxy groups, acyloxy groups, carbamoyloxy groups, aryloxycarbonyl groups, aryloxycarbonylamino groups, imide groups, heterocyclic thio groups, phosphoryl groups, acyl groups, carboxyl groups, carboxylic anhydride groups, sulfo groups, and salts thereof. In particular, in terms of compatibility with the first resin and the more uniform arrangement of microcapsules, carboxyl groups, carboxylic anhydride groups, hydroxyl groups, amino groups, phosphoryl groups, alkoxy groups, or sulfonamide groups are preferred, carboxyl groups, carboxylic anhydride groups, hydroxyl groups, amino groups, phosphoryl groups, ethyleneoxy groups, or propyleneoxy groups are more preferred, carboxyl groups, carboxylic anhydride groups, hydroxyl groups, or amino groups are even more preferred, and carboxyl groups or carboxylic anhydride groups are particularly preferred. Note that a carboxylic acid anhydride group refers to a monovalent substituent obtained by removing any hydrogen atom from carboxylic acid anhydrides such as maleic anhydride, itaconic anhydride, phthalic anhydride, pyromellitic anhydride, and trimellitic anhydride.

[0067] The first resin may have hydrophilic groups in either the main chain or the side chains, but it is preferable that the hydrophilic groups be in the side chains. Furthermore, the first resin preferably has a main chain consisting of a polyolefin structure. In particular, the first resin is more preferably a form having hydrophilic groups in at least one of the side chains branching from a main chain made of polyolefin structure and in the terminal portion of the main chain, and even more preferably a form having hydrophilic groups in at least the side chains. The first resin may be a resin obtained by copolymerizing the above-mentioned olefin with a monomer having a hydrophilic group, or a resin obtained by adding a compound having a hydrophilic group to a polymer obtained by polymerization of the above-mentioned olefin.

[0068] The first resin preferably has repeating units derived from olefins, specifically repeating unit A represented by the following formula (1) (hereinafter also simply referred to as "repeating unit A"). *-{CHR 11 -CR 12 R 13}-* (1) In formula (1), R 11 , R 12 and R 13 Each of these independently represents either a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. * indicates the connection position with an adjacent repeating unit.

[0069] R in equation (1) 11 and R 12 Each of these is independently preferably a hydrogen atom or a methyl group, with a hydrogen atom being more preferable. R in equation (1) 13 The component is preferably a hydrogen atom, a methyl group, or an ethyl group, and more preferably a hydrogen atom or a methyl group.

[0070] The first resin preferably has, in addition to the repeating unit A described above, at least one selected from the group consisting of a repeating unit B represented by the following formula (2-1) (hereinafter also simply referred to as "repeating unit B") and an end group represented by the following formula (2-2). *-{CHR 21 -CR 23 (LX n )}-* (2-1) *-LX n (2-2) In the formula, R 21 and R 23 Each of these independently represents either a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. L represents a single bond or a (n+1) valence linking group. X represents a carboxyl group, an anhydride carboxylic acid group, a hydroxyl group, an amino group, a phosphoryl group, an alkoxy group, or a sulfonamide group. n represents an integer between 1 and 5. If n is an integer between 2 and 5, then multiple X values ​​may be the same or different. * indicates the connection position with an adjacent repeating unit.

[0071] R in equation (2-1) 21 R is preferably a hydrogen atom or a methyl group, and more preferably a hydrogen atom. 11 and R 21 It is preferable that they are the same. R in equation (2-1) 23 The hydrogen atom, methyl group, or ethyl group is preferred, and the hydrogen atom or methyl group is more preferred. Also, R 13 and R 23 It is preferable that they are the same. The (n+1) valency linking group represented by L is not particularly limited as long as it has a valency corresponding to the number of X. Examples include aliphatic hydrocarbon groups, groups in which at least one methylene group contained in an aliphatic hydrocarbon group is substituted with a group selected from the group consisting of -O-, -CO-, -NH- and -NR- (where R represents an alkyl group), aromatic hydrocarbon rings, heterocyclic rings, and groups formed by combining these. Aliphatic hydrocarbon groups having 1 to 6 carbon atoms, or aliphatic hydrocarbon groups having 2 to 6 carbon atoms in which at least one methylene group contained in an aliphatic hydrocarbon group having 2 to 6 carbon atoms is substituted with a group selected from the group consisting of -O-, -CO- and -NH-, and aliphatic hydrocarbon groups having 1 to 4 carbon atoms are more preferred. X is preferably a carboxyl group, a carboxylic anhydride group, a hydroxyl group, an amino group, a phosphoryl group, an ethylene oxy group, or a propylene oxy group, and more preferably a carboxyl group or a carboxylic anhydride group. n is preferably an integer between 1 and 3, and more preferably 1 or 2. The repeating unit B is preferably a repeating unit that is different from both the repeating unit derived from acrylic acid and the repeating unit derived from methacrylic acid. Furthermore, when L represents a single bond, X preferably represents a carboxylic anhydride group.

[0072] Furthermore, "terminal group" refers to a group located at the terminal end of the main chain of the first resin containing the repeating unit A mentioned above. The preferred embodiments of L, X, and n in formula (2-2) are the same as those of L, X, and n in formula (2-1). When the first resin has both repeating units B and terminal groups represented by formula (2-2), L, X, and n in formula (2-1) and L, X, and n in formula (2-2) may be the same or different. The first resin more preferably has the repeating unit A and the repeating unit B.

[0073] Furthermore, the bonding pattern of the multiple repeating units in the first resin is not particularly limited. For example, the multiple repeating units may be bonded randomly (so-called random copolymer), alternately (so-called alternating copolymer), or in a block-like manner (so-called block copolymer).

[0074] Furthermore, it is preferable that the first resin is substantially free of halogen atoms. Here, "substantially free of halogen atoms" means that the halogen atom content is 1% by mass or less relative to the total mass of the first resin. More preferably, the halogen atom content in the first resin is 0.5% by mass or less, and even more preferably 0% by mass (below the detection limit). The halogen atom content in the first resin and the second resin described later can be measured, for example, by ion chromatography in accordance with IEC62321-3-2.

[0075] The acid value of the first resin is preferably 1 to 150 mg KOH / g, and more preferably 3 to 120 mg KOH / g, in that it provides better compatibility between the capsule and the second resin. Here, the acid value is the mass [mg] of potassium hydroxide required to neutralize 1 g of the sample, and in this specification, the unit is expressed as mgKOH / g. The acid value of the first resin can be measured in accordance with the method described in JIS K0070. Alternatively, when using a commercially available resin, the acid value listed in the catalog of that commercially available resin may be used as the acid value of that resin.

[0076] The weight-average molecular weight Mw of the first resin is not particularly limited, and is, for example, 500 to 100,000, with 1,000 to 80,000 being preferred. In this specification, unless otherwise specified, the weight-average molecular weight Mw is a value calculated using polystyrene as the standard substance, measured by a gel permeation chromatography (GPC) analyzer using TSKgel GMHxL, TSKgel G4000HxL, or TSKgel G2000HxL (all manufactured by Tosoh Corporation) as the column, tetrahydrofuran as the eluent, a differential refractometer as the detector, and polystyrene as the standard substance. In this specification, unless otherwise specified, the molecular weight of a compound having a molecular weight distribution is the weight-average molecular weight.

[0077] The melting point of the first resin is not particularly limited, but is preferably 90°C or higher, and more preferably 100°C or higher, from the standpoint of superior heat resistance of the heat storage sheet. The upper limit is not particularly limited, but is preferably 300°C or lower, and more preferably 250°C or lower, from the standpoint of superior moldability of the heat storage sheet. One method for measuring the melting point of resins and other materials is to use a differential scanning calorimeter (DSC).

[0078] The first resin contained in the heat storage sheet may be used alone or in combination of two or more types. The content of the first resin in the heat storage sheet is not particularly limited, but is preferably 1 to 30% by mass, more preferably 3 to 20% by mass, and even more preferably 3 to 15% by mass, relative to the total mass of the heat storage sheet.

[0079] [Second resin] This heat storage sheet contains a second resin, which is a different resin from the first resin and has repeating units derived from olefin.

[0080] The olefin in the second resin is the same as the olefin in the first resin, including its preferred embodiment. As the second resin, a resin having repeating units derived from olefins and lacking hydrophilic groups is preferred.

[0081] The second resin preferably has repeating units derived from olefins, specifically repeating unit C represented by the following formula (3) (hereinafter also simply referred to as "repeating unit C"). *-{CH2-CHR 3}-* (3) In formula (3), R 3 This represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. * indicates the connection position with an adjacent repeating unit.

[0082] R in equation (3) 3 The component is preferably a hydrogen atom, a methyl group, or an ethyl group, and more preferably a hydrogen atom or a methyl group. The second resin may have one repeating unit C alone, or it may have two or more repeating units C. The second resin may have repeating units other than repeating unit C.

[0083] The first resin and the second resin contained in the heat storage sheet preferably have repeating units derived from the same olefin, as this provides superior effects for the present invention. In particular, it is more preferable that the repeating units derived from olefin in the first resin include repeating units derived from ethylene, and the repeating units derived from olefin in the second resin include repeating units derived from ethylene, or that the repeating units derived from olefin in the first resin include repeating units derived from propylene, and the repeating units derived from olefin in the second resin include repeating units derived from propylene, and it is even more preferable that the repeating units derived from olefin in the first resin include repeating units derived from propylene, and the repeating units derived from olefin in the second resin include repeating units derived from propylene.

[0084] Furthermore, the bonding pattern of the multiple repeating units in the second resin is not particularly limited. For example, the multiple repeating units may be bonded randomly (so-called random copolymer), alternately (so-called alternating copolymer), or in a block-like manner (so-called block copolymer).

[0085] Furthermore, it is preferable that the second resin is substantially free of halogen atoms. In particular, the halogen atom content in the second resin is more preferably 1% by mass or less, and even more preferably 0% by mass (below the detection limit).

[0086] The melting point of the second resin is not particularly limited, but is preferably 110°C or higher, and more preferably 130°C or higher, from the standpoint of superior heat resistance of the heat storage sheet. The upper limit is not particularly limited, but is preferably 300°C or lower, and more preferably 250°C or lower, from the standpoint of superior moldability of the heat storage sheet. The softening point of the second resin is not particularly limited, but from the viewpoint of having better heat resistance and moldability of the heat storage sheet, 90 to 300°C is preferred, 100 to 250°C is more preferred, and 110 to 200°C is even more preferred.

[0087] The melt flow rate (MFR) of the second resin is preferably 1.0 to 15.0 g / 10 min, more preferably 3.0 to 10.0 g / 10 min, and even more preferably 3.0 to 8.0 g / 10 min. The MFR of the resin can be measured by a method in accordance with JIS K 7210. The density of the second resin is 800-1000 kg / m³. 3 Preferably, 850-950 kg / m 3 This is more preferable. The density of the resin can be measured by a method in accordance with JIS K 7112. The tensile modulus of the second resin is preferably 1 to 3000 MPa, more preferably 5 to 1500 MPa, and even more preferably 10 to 1000 MPa. The tensile modulus of the resin can be measured by a method in accordance with ASTM D638.

[0088] The second resin contained in the heat storage sheet may be used alone or in combination of two or more types. The content of the second resin in the heat storage sheet is not particularly limited, but it is preferably 10% by mass or more, more preferably 15% by mass or more, more preferably 18% by mass or more, and even more preferably 20% by mass or more, relative to the total mass of the heat storage sheet. There is no particular upper limit, but in terms of having better heat storage properties for the heat storage sheet, it is preferably 70% by mass or less, and more preferably 50% by mass or less.

[0089] In the heat storage sheet, it is preferable that the content of the second resin is greater than the content of the first resin. That is, the ratio of the content of the first resin to the total content of the first and second resins (content of the first resin / total content of the first and second resins) is preferably less than 50% by mass, more preferably less than 40% by mass, and even more preferably 35% by mass or less, in terms of achieving superior effects of the present invention.

[0090] The total content of the first resin and the second resin in the heat storage sheet is not particularly limited, but it is preferable that the content of the heat storage material be adjusted to fall within the range described above. The total content of the first resin and the second resin is preferably 10 to 90% by mass, more preferably 15 to 70% by mass, and even more preferably 20 to 65% by mass, relative to the total mass of the heat storage sheet, in terms of achieving superior effects of the present invention and superior heat storage properties of the heat storage sheet.

[0091] <Other ingredients> The heat storage sheet may contain the above-mentioned microcapsules, the first resin, and other components of the second resin. Other components include, for example, fillers, stabilizers, oxidation-reduction agents, molding aids, decomposition inhibitors, lubricants, mold release agents, colorants such as pigments, dispersants, and plasticizers. The filler is not particularly limited and includes, for example, inorganic fillers composed of glass, silica, wollastonite, aluminum hydroxide, kaolin, titanium oxide, alumina, mica, talc, carbon, and potassium titanate, as well as metallic fillers composed of copper and the like. The filler may be in particulate, fibrous, or whisker form.

[0092] Furthermore, the heat storage sheet may contain resins other than the first and second resins. Other resins include, for example, AS (acrylonitrile styrene) resin, ABS (acrylonitrile butadiene styrene) resin, polyester resin (polyether ester elastomer, etc.), polyvinyl chloride, polyvinylidene chloride, polyamide, acetal resin, polycarbonate resin, polyphenylene sulfide resin, polyetherimide resin, aromatic polyether ketone resin, polysulfone resin, fluororesin (polyvinylidene fluoride, etc.), polyamide-imide resin, and thermoplastic resins such as acrylic resin. The content of other resins is preferably 30% by mass or less, and more preferably 15% by mass or less, relative to the total mass of the heat storage sheet. There is no particular lower limit, and it may be 0% by mass. It is preferable that the heat storage sheet does not contain the above-mentioned other resins.

[0093] [Physical properties of heat storage sheets] The thickness of the heat storage sheet is, for example, 100 μm or more. In particular, 200 μm or more is preferred, 300 μm or more is more preferred, 500 μm or more is even more preferred, and 1.0 mm or more is especially preferred in terms of superior heat storage performance. There is no particular upper limit, but in terms of superior effects of the present invention, 1 cm or less is preferred, 5 mm or less is more preferred, and 3.5 mm or less is even more preferred. The thickness of the heat storage sheet is determined by measuring five arbitrary points with a contact-type thickness gauge and using the arithmetic mean obtained by adding the measured values ​​together.

[0094] While there are no particular limitations on the latent heat capacity of the heat storage sheet, 50 kJ / m is suitable because the heat storage material has high heat storage capacity and is suitable for temperature control of heat-generating elements. 2 The above is preferable, and 100 kJ / m³ 2 The above is more preferable, 130 kJ / m 2 The above is more preferable, with a 200 kJ / m³ 2 The above is even more preferable. There is no particular upper limit, but 500 kJ / m³ is preferable. 2 The following are common cases. Latent heat capacity is the amount of heat stored per unit mass (J / g) measured by differential scanning calorimetry (DSC), and the density of the heat storage sheet (g / cm³). 3 The heat storage capacity per unit area of ​​the heat storage sheet is calculated from the area and thickness (mm) of the heat storage sheet. The density of the heat storage sheet is measured from the mass and volume of the sample. The mass of the sample is measured using an electronic balance. The volume of the sample is calculated by measuring the area and thickness with calipers and a contact-type thickness measuring instrument, or by immersing it in a solvent that does not dissolve or swell (water, alcohol, etc.) and determining the volume increase.

[0095] It is preferable that the microcapsules are uniformly arranged in the heat storage sheet, as this improves the conformability of the heat storage sheet and further enhances the effects of the present invention. The inter-surface distance of the microcapsules contained in the heat storage sheet is preferably 1 nm or more, more preferably 10 nm or more, even more preferably 50 nm or more, and particularly preferably 100 nm or more. A larger inter-surface distance means that the particles exist without agglomerating in the resin. The upper limit is, for example, 500 μm.

[0096] The inter-surface distance of microcapsules can be measured by the following method. The inside of the microcapsule, the capsule wall, and the outer region of the microcapsule are observed separately using a scanning electron microscope (SEM), similar to the method used to measure the average particle size and average inner diameter of microcapsules. The outer circumference of the microcapsules present in the observed field of view is traced, and the average inter-surface distance of each microcapsule is measured from the traced image using an image analysis device. The value calculated by averaging the total of 20 measurement points obtained from each observation image is defined as the "inter-surface distance" of the microcapsule.

[0097] [Method for manufacturing heat storage sheets] The method for manufacturing the heat storage sheet is not particularly limited and known methods can be used. A method for manufacturing a heat storage sheet includes a resin pellet manufacturing step for producing resin pellets containing microcapsules, a first resin, and a second resin, and a film forming step for forming the obtained resin pellets into a sheet.

[0098] <Resin Pellet Manufacturing Process> The method for producing resin pellets containing microcapsules, a first resin, and a second resin is not particularly limited and includes known methods. For example, one method involves melt-kneading a mixture containing microcapsules, a first resin, and a second resin in an extruder, and then cutting the strand extruded from the extruder to form pellets. As the extruder used in the production of resin pellets, known devices can be used, such as known extrusion molding machines like twin-screw extruders.

[0099] It is preferable to handle the microcapsules as a powder. One method for obtaining the microcapsule powder is to remove the solvent from the microcapsule dispersion obtained by the interfacial polymerization method described above. One method for removing the solvent is to use a spray dryer to obtain the microcapsule powder from the microcapsule dispersion.

[0100] In particular, a method is preferred in which the first resin and the second resin are melt-kneaded in an extruder, microcapsules are added to the molten mixture of the first and second resins in the extruder and further melt-kneaded, and the strands extruded from the extruder are cut to produce resin pellets, as this method can further suppress the destruction of microcapsules during melt-kneading. The above method can be carried out by using an extruder equipped with multiple raw material supply ports. For example, a first resin and a second resin can be supplied to an extruder equipped with multiple raw material supply ports and melt-mixed, microcapsules can be supplied to the extruder from a raw material supply port located downstream of the raw material supply ports from which the first and second resins were supplied and melt-mixed further, and the strands extruded from the extruder can be cut to produce resin pellets. The above method corresponds to a method of side-feeding microcapsules into an extruder and mixing them with the softened first and second resins. Side-feeding is a method in which a feeder for supplying microcapsules is installed separately from the feeders for supplying the first and second resins, and the microcapsules are introduced into the first and second resins, which have been pre-mixed in the extruder.

[0101] (Resin pellets) The resin pellets produced by the above resin pellet process include the microcapsules, the first resin, and the second resin as described above. In other words, the resin pellet manufacturing process described above allows for the production of the present invention, which includes microcapsules containing a heat storage material, the first resin, and the second resin, wherein the capsule walls of the microcapsules contain the resin W. The components contained in the resin pellets of the present invention, including their preferred embodiments, may be the same as those already described for each component contained in the heat storage sheet. The resin pellets of the present invention can be used in the manufacture of this heat storage sheet, and can also be used in the manufacture of molded products as described later. The present invention is not limited to the resin pellet manufacturing process described above, and known resin pellet manufacturing methods can be applied.

[0102] The shape of the resin pellets is not particularly limited, nor is their size. The resin pellets are preferably cylindrical or prismatic in shape, with cylindrical being more preferred. For cylindrical resin pellets, a cylindrical pellet with a height of 0.01 to 100 mm (more preferably 0.05 to 10 mm) and a diameter of 0.01 to 50 mm (more preferably 0.05 to 30 mm) is preferred. A higher heat storage capacity for the resin pellets is preferable. The heat storage capacity of the resin pellets is preferably 30 J / g or more, more preferably 50 J / g or more, even more preferably 65 J / g or more, and particularly preferably 80 J / g or more. There is no particular upper limit, but it is often 300 J / g or less. The heat storage capacity can be measured by DSC in accordance with the method for measuring the heat storage capacity of the heat storage sheet described above.

[0103] <Film forming process> The film formation process involves molding the resin pellets produced by the above process into a sheet to produce a heat storage sheet containing microcapsules, a first resin, and a second resin. The method for forming the resin pellets into a sheet during the film formation process is not particularly limited, and known molding methods such as extrusion molding, injection molding, blow molding, compression molding, press molding, and molding with a 3D printer are examples of such methods. Extrusion molding is preferred because it offers superior productivity.

[0104] In the film-forming process by extrusion molding, for example, a heat storage sheet, which is a sheet-shaped extruded product, is manufactured by melting resin pellets using a molten extruder, extruding the molten material from an extrusion die, and then cooling the extruded molten material. Methods for cooling the molten material include, for example, a method of cooling the molten material by allowing it to cool from the time the single film of the molten material is extruded from the extrusion die until it is wound up, and a method of bringing the molten material extruded from the extrusion die into contact with a casting roll and cooling the molten material on the casting roll. Furthermore, when cooling the molten material, it is preferable to blow air (preferably cold air) onto the molten material. For heat storage sheets, it is preferable that they be extruded products manufactured by extrusion molding, as this offers superior productivity.

[0105] Furthermore, as a method for manufacturing a heat storage sheet, separate from the resin pellet manufacturing process and film formation process described above, there is a method comprising a coating solution preparation step of mixing the microcapsules, the first resin, the second resin, and a solvent to prepare a coating solution; a coating step of applying the obtained coating solution onto a substrate to form a coating film; and a drying step of drying the formed coating film. For the method of manufacturing the heat storage sheet described above, please refer to paragraphs

[0086] to

[0092] of International Publication No. 2020 / 110662, the contents thereof are incorporated herein by reference.

[0106] [Uses of heat storage sheets] The heat storage sheet can be applied to a variety of uses, such as electronic devices (e.g., mobile phones (especially smartphones), personal information terminals, personal computers (especially portable personal computers), game consoles, wireless chargers, cameras, projectors, hard disks, wearable devices (smartwatches, smart glasses, headphones), and remote controls); automotive parts (e.g., batteries (especially lithium-ion batteries), control devices such as power ICs (Integrated Circuits), car navigation systems, LCD monitors, LED (Light Emitting Diode) lamps, and heat retention for canisters); building materials suitable for temperature control during rapid temperature increases in the day or when heating and cooling indoors (e.g., flooring materials, roofing materials, and wall materials); clothing suitable for temperature control in response to changes in ambient temperature or changes in body temperature during exercise or rest (e.g., underwear, jackets, winter clothing, and gloves); air conditioners; bedding; and waste heat utilization systems that store unwanted exhaust heat and use it as thermal energy.

[0107] In particular, heat storage sheets are preferably used in electronic devices (especially portable electronic devices). By introducing the above-mentioned heat storage sheet into an electronic device, it is possible to suppress the temperature rise of the electronic device while maintaining the airtightness and waterproofness of the electronic device. In other words, the heat storage sheet creates a part in the electronic device where heat can be stored for a certain period of time, so the surface temperature of the heating element inside the electronic device can be maintained within a desired temperature range.

[0108] [Heat storage material] The heat storage sheet used for the above applications may also be in the form of a heat storage member, which is a combination of the heat storage sheet and other components. Examples of components other than the heat storage sheet include an adhesive layer and a protective layer. The heat storage material can be applied to the applications listed above for the heat storage sheet.

[0109] The heat storage member may be a resin sheet with an adhesive layer, wherein an adhesive layer is provided on at least one surface of the heat storage sheet for the purpose of improving adhesion to the object. Examples of adhesive layers in a resin sheet with an adhesive layer include a tacky layer and a bonding layer.

[0110] The material of the adhesive layer is not particularly limited and includes known adhesives. Examples of adhesives include acrylic adhesives, rubber adhesives, and silicone adhesives. Furthermore, examples of adhesives include acrylic adhesives, UV-curing adhesives, and silicone adhesives described in Chapter 2 of "Characterization and Control Technology for Release Paper, Release Film, and Adhesive Tape," Information Organization, 2004. Furthermore, acrylic adhesives refer to adhesives that contain polymers of (meth)acrylic monomers ((meth)acrylic polymers). The adhesive layer may further contain a tackifier.

[0111] The material of the adhesive layer is not particularly limited and includes known adhesives. Examples of adhesives include urethane resin adhesives, polyester adhesives, acrylic resin adhesives, ethylene vinyl acetate resin adhesives, polyvinyl alcohol adhesives, polyamide adhesives, and silicone adhesives.

[0112] The thickness of the adhesion layer is not particularly limited, but is preferably 0.5 to 100 μm, more preferably 1 to 25 μm, and even more preferably 1 to 15 μm. Alternatively, the amount of adhesive or bonding agent applied to the bonding layer relative to the area of ​​the heat storage sheet is 0.1 to 100 g / m². 2 Preferably, it is 1 to 50 g / m 2 It is preferable that it be so. The method for forming the adhesion layer is not particularly limited. Examples include a method of forming the adhesion layer by applying a composition containing an adhesive or bonding agent onto a heat storage sheet, and a method of transferring the adhesion layer onto a heat storage sheet.

[0113] The protective layer is a layer that serves to protect the heat storage sheet. As the protective layer, for example, a layer or hard coat film containing a known hard coat agent as described in Japanese Patent Publication No. 2018-202696, Japanese Patent Publication No. 2018-183877, and Japanese Patent Publication No. 2018-111793 may be used. Alternatively, from the viewpoint of heat storage, a protective layer having a heat-storing polymer as described in International Publication No. 2018 / 207387 and Japanese Patent Publication No. 2007-031610 may be used.

[0114] [Molded products] The molded article of the present invention (hereinafter also referred to as "this molded article") comprises a microcapsule containing a heat storage material, a first resin having repeating units derived from olefins and having hydrophilic groups, and a second resin different from the first resin, which also has repeating units derived from olefins. Furthermore, the capsule wall of the microcapsule contains at least one resin W selected from the group consisting of polyurethane urea, polyurethane, and polyurea. Because this molded product has excellent conformability, it deforms to follow the surface shape of the object, adhering tightly to the object without gaps and allowing the heat storage material to fully exert its heat absorption function. Furthermore, because this molded product has excellent heat resistance, deformation is less likely to occur even when used in high-temperature environments, and a decrease in adhesion to the surface of the object can be suppressed. Based on the above, this molded product can further improve the heat absorption function when applied to an object.

[0115] The components contained in this molded product, as well as its physical properties, including preferred embodiments, may be the same as those already described for this heat storage sheet. The shape of the molded product is not particularly limited and may be a solid form (three-dimensional shape) such as a sheet, film, plate, cylindrical, spherical, lump, tube, tubular, or box.

[0116] This molded product can be used for a variety of applications. In addition to the same applications as the heat storage sheet described above, other applications of the molded product include, for example, automotive parts, electronic equipment parts, and textiles (clothing). Examples of automotive parts include engine covers, battery cases, heat exchangers, interior components, and vehicle intake system piping. Examples of components for electronic devices include housings and battery cases.

[0117] This molded product can be manufactured, for example, using resin pellets obtained in the resin pellet manufacturing process described above. The method for manufacturing this molded product using resin pellets is not particularly limited, and known molding methods can be applied. Examples of molding methods include extrusion molding, injection molding, blow molding, compression molding, press molding, and molding with a 3D printer.

[0118] The method for manufacturing the molded product is not limited to the molding method using the resin pellets described above. The molded product may also be manufactured by directly molding a mixture containing microcapsules, a first resin, and a second resin into the desired shape. The mixture used in the manufacture of the molded product and the heat storage sheet is not particularly limited as long as it includes a combination of microcapsules having a capsule wall containing a predetermined resin W, a predetermined first resin, and a predetermined second resin. The mixture containing the above combination may be in the form of, for example, a paste, liquid, powder, clay, or gel. [Examples]

[0119] The features of the present invention will be further described below with reference to examples and comparative examples. The materials, amounts used, proportions, processing content, and processing procedures shown in the following examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted restrictively by the specific examples shown below.

[0120] [Preparation of microcapsule A] As a heat storage material, 100 parts by mass of paraffin wax (Paraffin Wax-155, manufactured by Nippon Seiro Co., Ltd., melting point 69°C) was added to 120 parts by mass of ethyl acetate and heated to 75°C to dissolve and obtain solution A. Furthermore, 16 parts by mass of trimethylolpropane adduct of tolylene diisocyanate (Barnock D-750, containing 25% ethyl acetate, manufactured by DIC Corporation) and 40 parts by mass of polymethylene polyphenyl polyisocyanate (Millionate MR-200, manufactured by Tosoh Corporation) were added to the stirred solution A to obtain solution B. 170 parts by mass of a 3% by mass aqueous solution of polyvinyl alcohol (Kuraray Poval 25-88KL, manufactured by Kuraray Co., Ltd.) was added to 970 parts by mass of water. The resulting mixture was kept warm at 75°C and, while stirring, solution B was added to emulsify and disperse. The emulsion after dispersion was heated to 85°C while stirring, stirred for 3 hours, and then cooled. Furthermore, water was added to the obtained solution to adjust the concentration, and a microcapsule solution containing a heat storage material with a solid content of 15% was obtained.

[0121] As shown in the following structural formula, the above-mentioned Barnock D-750 is a trifunctional polyisocyanate, which is an adduct of an aromatic diisocyanate and trimethylolpropane. The above-mentioned Millionate MR-200 is a mixture of diphenylmethane diisocyanate and polymethylene polyphenyl polyisocyanate (corresponding to the compound represented by formula (X)).

[0122] [ka]

[0123] Next, the liquid containing the heat storage material in microcapsules prepared above was powdered using a spray dryer (mini spray dryer B-290, manufactured by Büch) to obtain powder of the heat storage material containing microcapsules A. The particle size of the obtained microcapsules A was 15 μm.

[0124] [Preparation of microcapsules B-C] Microcapsules B and C were prepared in the same manner as microcapsule A, except that the amount of heat storage material contained in the microcapsules was changed as shown in Table 1.

[0125] [Preparation of Microcapsule D] In the preparation of the heat storage material-containing capsule liquid in Example 1, microcapsule D was prepared in the same manner as microcapsule A, except that myrionate MR-200 was not added as the wall material of the microcapsule, and the amount of Barnock D-750 (containing 25% ethyl acetate) added was changed to 65.3 parts by mass.

[0126] [Preparation of microcapsule E] Microcapsule E was prepared using the same method as microcapsule A, except that the heat storage material was changed from paraffin wax (Paraffin Wax-155) to paraffin wax with a melting point of 75°C (HNP-9, manufactured by Nippon Seiro Co., Ltd., melting point 75°C).

[0127] [Preparation of microcapsules F-I] Microcapsule F was prepared using the same method as microcapsule A, except that the heat storage material was changed from paraffin wax with a melting point of 69°C (Paraffin Wax-155) to paraffin wax with a melting point of 63°C (Paraffin Wax-145, manufactured by Nippon Seiro Co., Ltd.). Similarly, microcapsules G, which were created by changing the paraffin wax with a melting point of 69°C (Paraffin Wax-155) to a paraffin wax with a melting point of 61°C (Paraffin Wax-140, manufactured by Nippon Seiro Co., Ltd.), microcapsule H, which was created by changing the paraffin wax with a melting point of 56°C (Paraffin Wax-130, manufactured by Nippon Seiro Co., Ltd.), and microcapsule I, which was created by changing the paraffin wax with a melting point of 48°C (Paraffin Wax-115, manufactured by Nippon Seiro Co., Ltd.), were each prepared using the same method as microcapsule A.

[0128] [Create microcapsules J-K] A microcapsule J was obtained containing 50% by mass of paraffin wax with a melting point of 48°C as a heat storage material, and having melamine resin as the capsule wall. A microcapsule K was obtained containing 50% by mass of paraffin wax with a melting point of 48°C as a heat storage material, and having polymethyl methacrylate (PMMA) resin as the capsule wall.

[0129] [Example 1] Using a twin-screw extruder (2D25S, manufactured by Toyo Seiki Seisakusho Co., Ltd.) equipped with a first raw material supply port located upstream and a second raw material supply port located downstream, 10 parts by mass of resin A (described later) and 25 parts by mass of PO-A (described later) were fed into the twin-screw extruder from the first raw material supply port and melted at a melting temperature of 180°C. In addition, 65 parts by mass of the powder of the heat storage material-containing microcapsule A were fed into the twin-screw extruder from the second raw material supply port, and the molten thermoplastic resin and the powder of the heat storage material-containing microcapsule were kneaded together. The molten material obtained in the twin-screw extruder was extruded from the die to form strands, and the strands were cut to form pellets, thereby producing cylindrical resin pellets (3 mm in diameter x 3 mm in height).

[0130] The above resin pellets were fed into a melt extrusion molding machine ("GT-20-A", manufactured by Plastics Engineering Research Institute Co., Ltd.), and melt extrusion molding was performed at an extrusion temperature of 180°C and a take-up speed of 1 m / min to produce a heat storage sheet with a thickness of 3 mm. Furthermore, an adhesive ("SK Dyne® 1717DT", manufactured by Soken Chemical Co., Ltd.) is applied to the heat storage sheet at a rate of 10 g / m². 2 A heat-storage sheet with adhesive was fabricated by coating it with the specified amount of material.

[0131] [Examples 2-22, Comparative Example 1] As shown in Table 1 described later, resin pellets, a heat storage sheet, and an adhesive-coated heat storage sheet were manufactured following the same procedure as in Example 1, except that at least one of the following was changed: the type of microcapsules used, the amount of heat storage material in the microcapsules, the type of heat storage material, the type of resin, the amount of each component, and the thickness of the heat storage sheet to be manufactured.

[0132] The contents of each column in Table 1, which will be described later, are as follows: In the "Resin W" column of "Microcapsules," "Urethane A" refers to polyurethane resin A, which is formed by the reaction of a trimethylolpropane adduct of tolylene diisocyanate with polymethylene polyphenyl polyisocyanate, and has a polymethylene polyphenylene structure. In the "Resin W" column of "Microcapsules," "Urethane B" refers to polyurethane resin B, which is formed by the reaction of tolylene diisocyanate with a trimethylolpropane adduct. This polyurethane resin B does not have a polymethylene polyphenylene structure. The "Heat Storage Material / Capsule" column for "Microcapsules" indicates the amount of heat storage material relative to the total mass of the microcapsules. The "Heat Storage Material (Melting Point)" column under "Microcapsules" shows the melting point (phase change temperature) (°C) of the heat storage material used in the manufacture of the microcapsules in each example. The "Quantity" column for "Microcapsules" indicates the amount of microcapsules relative to the total mass of the heat storage sheet or resin pellet (unit: mass%).

[0133] In the table, the "Component 1" column indicates the first resin or reference component. The "Type" column under "Component 1" indicates the component used in each example. • Resin A: "Yumex 5200" manufactured by Sanyo Chemical Industries, Ltd. (maleic anhydride-modified polypropylene, melting point 124°C, acid value 11 mg KOH / g, Mw 70,000) • Resin B: "Yumex 1001" manufactured by Sanyo Chemical Industries, Ltd. (maleic acid-modified polypropylene, melting point 142℃, acid value 26 mgKOH / g, Mw 45,000) • Resin C: Mitsui Chemicals, Inc. "High Wax 1105A" (maleic acid-modified polyolefin, melting point 104°C, acid value 60 mg KOH / g, Mw 1,500) • Resin D: DuPont's "ELVALOY AC 3427" (butyl acrylic acid polymer) The resins A through D described above all correspond to the first resin. The acid values ​​of resins A and B were measured using the method described above. The "Quantity" column for "Component 1" indicates the amount of Component 1 relative to the total mass of the heat storage sheet or resin pellet (unit: mass%). The "Ratio" column for "Component 1" shows the ratio (in mass %) of the content of Component 1 to the total content of Component 1 and Component 2.

[0134] In the table, the "Component 2" column indicates the second resin or reference component. The "Type" column in "Component 2" indicates the component used in each example. • PO-A: Polyolefin-modified resin ("Tafmer® PN-2070" manufactured by Mitsui Chemicals, Inc., thermoplastic resin, melting point 140°C, softening point 125°C, density 867 kg / m³) 3 (MFR 7.0g / 10 min, tensile modulus 14 MPa) • PO-B: Polyolefin modified resin ("Tafmer PN-3560" manufactured by Mitsui Chemicals, Inc., thermoplastic resin, melting point 160℃, softening point 135℃, density 866 kg / m³) 3 (MFR 6.0g / 10 min, tensile modulus 11 MPa) • PO-C: Polyolefin-modified resin ("Tafmer PN-2060" manufactured by Mitsui Chemicals, Inc., thermoplastic resin, melting point 160°C, softening point 120°C, density 868 kg / m³) 3 (MFR 6.0g / 10 min, tensile modulus 22 MPa) • PP: Polypropylene resin (Novatec® PP MA-3 manufactured by Nippon Polypropylene Co., Ltd., thermoplastic resin, melting point 170℃, density 900kg / m³) 3 (MFR 11.0g / 10 min, tensile modulus 1500 MPa) All of the above resins correspond to the second type of resin. The "Quantity" column for "Component 2" indicates the content of Component 2 relative to the total mass of the heat storage sheet or resin pellet (unit: mass%).

[0135] [Comparative Example 2] A heat storage sheet was manufactured based on Example 1 of Patent Document 2. However, in Comparative Example 2, microcapsules K were used as the microcapsules contained in the heat storage sheet. Furthermore, the heat storage sheet of Comparative Example 2 contains the following components in addition to the microcapsule K mentioned above. • Polyvinyl chloride (PVC) resin (ZEST® PQ92 manufactured by Shin-Daiichi Vinyl Chloride Co., Ltd., thermoplastic resin): In Table 1, "PVC" is indicated in the "Type" column of "Component 2". • Dispersant (BYK's "Disperplast-1150," a polar acid ester of long-chain alcohols): In Table 1, under "Component 1," the "Type" column is labeled "Dispersant E." • Epoxy plasticizer (DIC Corporation's "Monosizer W-150", viscosity 85 mPa·s, gelation endpoint temperature 121℃) • Heat stabilizer (Grec ML-538, manufactured by Showa Varnish Co., Ltd.) • Viscosity reducer (VISCOBYK-5125, manufactured by BYK)

[0136] In the table, the "Heat Storage Material / Heat Storage Sheet" column indicates the amount of heat storage material relative to the total mass of the heat storage sheet. In the table, the "Thickness" column shows the thickness (in mm) of the heat storage sheets manufactured in each example and comparative example.

[0137] 〔evaluation〕 <Heat storage amount> The heat storage capacity of the heat storage sheets prepared in the examples and comparative examples was measured using a differential scanning calorimeter (DSC7020, manufactured by Hitachi High-Tech Science Corporation) with the method described above. The measurement results are shown in Table 1.

[0138] <Followability> The heat storage sheets prepared in the examples and comparative examples were wrapped around a 10 cm diameter cylinder so that the side opposite to the adhesive-coated side was in contact with the outer surface of the cylinder, and the wrapped state was fixed for 24 hours to maintain that state. After that, the fixing was removed, and the boundary between the cylinder and the heat storage sheet, as well as the appearance of the outer surface of the heat storage sheet, were visually observed, and the conformability of the heat storage sheet was evaluated according to the following criteria. A: The heat storage sheet is wrapped around the cylinder without any gaps, and a change in the surface morphology of the heat storage sheet is observed. B: A gap is observed between the heat storage sheet and the cylinder, or cracks are observed on the surface of the heat storage sheet. C: A gap was observed between the heat storage sheet and the cylinder, and cracks were observed on the surface of the heat storage sheet.

[0139] <Heat resistance> Each heat storage sheet prepared in the examples and comparative examples was heated at 80°C for 1 hour. The deformation of the heat storage sheets after heating was visually observed, and the heat resistance of the heat storage sheets was evaluated according to the following criteria. A: Little to no deformation is observed. B: Slight deformation is observed. C: Significant deformation is observed.

[0140] <Heat storage effect> A heat storage sheet with adhesive, the same size as the copper plate, was attached to one surface of a 10cm x 5cm x 0.5mm thick copper plate, with the adhesive side facing the copper plate. A ceramic heater was attached to the other surface of the copper plate. The copper plate was heated by the ceramic heater at an output of 6W, and the temperature change of the copper plate was measured using a thermocouple. The time it took to reach 80°C from the start of heating was measured. The temperature of the copper plate before heating was 25°C. The heat storage effect of each heat storage sheet was evaluated from the measured time according to the following criteria. A: Longer than 300 seconds. B: Longer than 200 seconds, but 300 seconds or less. C: Longer than 100 seconds, but 200 seconds or less. D: Less than 100 seconds.

[0141] <Breeding> Each heat storage sheet prepared in the examples and comparative examples was heat-treated at 80°C for 4 hours. The surface of the heat-treated heat storage sheets was visually inspected to see if any bleeding (leakage) of the heat storage material was observed, and evaluated according to the following criteria. A: No breeding was confirmed. B: A slight case of inbreeding was observed. C: Breeding was clearly confirmed.

[0142] [Table 1]

[0143] As shown in Table 1, the heat storage sheet and resin pellets of the present invention were confirmed to exhibit the desired effects compared to the heat storage sheets and resin pellets of Comparative Examples 1 and 2, which do not contain a combination of microcapsules with a specific resin W in their capsule walls, a first resin, and a second resin.

[0144] From a comparison of Examples 1-4 and 6, it was confirmed that the effects of the present invention are superior when the ratio of the content of the first resin to the total content of the first and second resins is less than 40% by mass (see reference). From a comparison of Examples 1 to 5 and 8 to 10, it was confirmed that bleeding of the heat storage material can be further suppressed when the content ratio of the heat storage material relative to the total mass of the microcapsules is 70 mass% or less.

[0145] From a comparison of Example 7 and Examples other than Example 7, it was confirmed that bleeding of the heat storage material can be further suppressed when the resin W has a polymethylene polyphenylene structure. From a comparison of Example 10 and Examples other than Example 10, when the content of the heat storage material is 20 mass% or more relative to the total mass of the heat storage sheet, 1 m 2 It was confirmed that the heat storage amount per unit is more excellent.

[0146] From a comparison of Example 1 and Examples 15 to 19, it was confirmed that when the melting point of the heat storage material is 50°C or higher, the heat storage effect is more excellent; when the melting point of the heat storage material is 60°C or higher, the heat storage effect is further excellent; and when the melting point of the heat storage material is 65°C or higher, the heat storage effect is particularly excellent.

[0147] From a comparison of Example 1 and Examples 20 to 22, it was confirmed that when the thickness of the heat storage sheet is 3.5 mm or less, the effect of the present invention is more excellent. Furthermore, from a comparison of Example 1 and Examples 20 to 22, it was confirmed that when the thickness of the heat storage sheet is 2.5 mm or more, the heat storage effect is more excellent. [Description of Reference Numerals]

[0148] 10 Microcapsule 10a Capsule wall 10b Inclusion 12 Thermoplastic resin 13 Heat storage sheet

Claims

1. Microcapsules containing heat storage material, A first resin having repeating units derived from olefins and having hydrophilic groups, A heat storage sheet comprising a second resin, which is different from the first resin and has repeating units derived from olefin, A heat storage sheet in which the capsule walls of the microcapsules contain at least one resin W selected from the group consisting of polyurethane urea, polyurethane, and polyurea.

2. The repeating units derived from the olefin in the first resin include repeating units derived from ethylene, and the repeating units derived from the olefin in the second resin include repeating units derived from ethylene, or The heat storage sheet according to claim 1, wherein the repeating units derived from the olefin in the first resin include repeating units derived from propylene, and the repeating units derived from the olefin in the second resin include repeating units derived from propylene.

3. The heat storage sheet according to claim 1, wherein the repeating units derived from the olefin in the first resin include repeating units derived from propylene, and the repeating units derived from the olefin in the second resin include repeating units derived from propylene.

4. The heat storage sheet according to any one of claims 1 to 3, wherein the hydrophilic group is at least one group selected from the group consisting of a carboxyl group, a carboxylic anhydride group, a hydroxyl group, and an amino group.

5. The heat storage sheet according to any one of claims 1 to 3, wherein the thickness of the heat storage sheet is 200 μm or more.

6. The heat storage sheet according to any one of claims 1 to 3, wherein the heat storage material has a melting point of 50 to 95°C.

7. The heat storage sheet according to any one of claims 1 to 3, wherein the content of the heat storage material is 15% by mass or more of the total mass of the heat storage sheet.

8. A heat storage sheet according to any one of claims 1 to 3, which is an extruded product.

9. The heat storage sheet according to any one of claims 1 to 3, wherein the content of the second resin is 15% by mass or more with respect to the total mass of the heat storage sheet.

10. The heat storage sheet according to any one of claims 1 to 3, wherein the content of the second resin is greater than the content of the first resin.

11. The heat storage sheet according to any one of claims 1 to 3, wherein the resin W has a polymethylene-polyphenylene structure.

12. Microcapsules containing heat storage material, A first resin having repeating units derived from olefins and having hydrophilic groups, A resin pellet comprising a second resin, which is different from the first resin and has repeating units derived from olefin, A resin pellet in which the capsule wall of the microcapsule contains at least one resin W selected from the group consisting of polyurethane urea, polyurethane, and polyurea.

13. The resin pellet according to claim 12, wherein the hydrophilic group is at least one group selected from the group consisting of a carboxyl group, a carboxylic anhydride group, a hydroxyl group, and an amino group.

14. The resin pellet according to claim 12 or 13, wherein the heat storage material has a melting point of 50 to 95°C.

15. The resin pellet according to claim 12 or 13, wherein the content of the heat storage material is 15% by mass or more with respect to the total mass of the resin pellet.

16. The resin pellet according to claim 12 or 13, wherein the second resin is a thermoplastic resin, and the content of the thermoplastic resin is 15% by mass or more with respect to the total mass of the resin pellet.

17. The resin pellet according to claim 12 or 13, wherein the content of the second resin is greater than the content of the first resin.

18. Microcapsules containing heat storage material, A first resin having repeating units derived from olefins and having hydrophilic groups, A molded article comprising a second resin, which is different from the first resin and has repeating units derived from olefin, A molded article in which the capsule wall of the microcapsule contains at least one resin W selected from the group consisting of polyurethane urea, polyurethane, and polyurea.

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