Microcapsules containing bio-based phase change materials

Abstract

The composition exhibits good thermal stability and contains microcapsules comprising a core and a shell. The core comprises (A) a phase change material component, which comprises (A1) a fatty acid ester, (A2) 1 to 6 weight percent of a fatty acid having 10 to 18 carbon atoms based on the weight of the fatty acid ester, and (A3) 0 to 10 weight percent of a fatty alcohol based on the weight of the fatty acid ester. The shell comprises the reaction product of an isocyanate component and an amine compound, which comprises (B1) 1 to 20 weight percent of an aliphatic isocyanate having at least two isocyanate groups, and (B2) 1 to 20 weight percent of an aromatic isocyanate having at least two isocyanate groups, based on the weight of the phase change material component. The weight ratio of aliphatic isocyanate to aromatic isocyanate is in the range of 8.5:1.5 to 1.5:8.5. The amine compound comprises at least two amino functional groups selected from primary amino groups, secondary amino groups, or combinations thereof. The amine compound is present in an amount that provides a molar ratio of primary amino groups to secondary amino groups and isocyanate groups in the range of 0.3:1 to 1.5:1. Methods for preparing the composition are also disclosed.

Description

[Technical Field]

[0001] The present invention relates to microcapsules containing a bio-based phase change material as a core, and to a method for preparing such microcapsules. [Background technology]

[0002] Introduction Phase change materials (PCMs) are widely used in many applications, including building materials. Before being incorporated into the matrix of building materials, PCMs such as paraffin wax are typically microencapsulated to prevent leakage using various microcapsule manufacturing techniques, including interfacial polymerization and in-situ polymerization. A typical interfacial polymerization technique for preparing PCM-containing microcapsules may involve: forming an oil phase mixture containing the PCM as the core material, an isocyanate, and optionally an organic solvent; emulsifying the oil phase mixture in an aqueous solution with an emulsifier under high shear mixing (i.e., mixing at a rate exceeding 1500 revolutions per minute); and then adding a reactive alcohol or amine to the aqueous solution, which is then reacted with the isocyanate at the interface of the two phases to form a polyurethane or polyurea shell that encapsulates the core material. The emulsification step is crucial for successful encapsulation of PCMs using interfacial polymerization. However, high shear mixing typically results in increased energy consumption, as well as increased equipment and manufacturing costs. Furthermore, aqueous surfactants or colloidal stabilizers are undesirable due to the difficulty in recycling reactor effluents, and may also adversely affect the mechanical properties of building materials into which PCM microcapsules are incorporated. Moreover, the use of solvents poses more environmental problems than aqueous compositions.

[0003] Paraffin wax is widely used as a core material for PCM microcapsules due to its advantages in energy storage density, chemical stability, and volume change during phase transition processes. However, paraffin wax is neither renewable nor biodegradable. It is even more desirable to use renewable raw materials instead of fossil raw materials, thereby reducing greenhouse gas emissions and contributing to sustainability. Bio-based phase transition materials may be good candidates. However, it is difficult to encapsulate bio-based PCMs derived from plant and animal fats in the resulting microcapsules while providing the desired encapsulation performance, such as thermal stability and particle size, which is particularly suitable for building applications.

[0004] It is desirable to discover a novel method for producing encapsulated PCMs that can still provide PCM microcapsules containing bio-based PCMs and having good thermal stability, without the aforementioned problems. [Overview of the project]

[0005] The present invention solves the problem of discovering a method that is suitable for preparing microencapsulated bio-based phase change materials (PCMs) without the aforementioned problems, and that can form microcapsules particularly suitable for use in building materials.

[0006] The present invention provides a composition comprising a microcapsule (used interchangeably as "microencapsulated PCM" or "PCM microcapsule") comprising a novel combination of at least one fatty acid ester and a specific amount of at least one fatty acid as a core material, and a polyurea shell containing a reaction product of a mixture of at least one aliphatic isocyanate and at least one aromatic isocyanate with an amine compound. The microcapsule exhibits good thermal stability and density, as indicated, for example, by a weight loss of less than 20 weight percent when heated at 105 degrees Celsius (°C) for 24 hours (further details are provided in the thermal stability tests described in the Examples section below). Surprisingly, it has been found that such microcapsules can be prepared by a method involving the addition of an oil phase mixture containing isocyanates and PCM to an aqueous amine solution, without requiring a step of emulsifying the oil phase mixture using emulsifiers and / or high-shear mixing. Preferably, since the oil phase mixture is a self-emulsifying component, this method is carried out in the absence of emulsifiers and / or organic solvents.

[0007] In a first embodiment, the present invention relates to a composition comprising a microcapsule having a core and a shell, The core contains phase change material components, and the phase change material components are (A1) Fatty acid ester, (A2) 1 to 6 weight percent of fatty acids having 10 to 18 carbon atoms, based on the weight of fatty acid esters, and (A3) Contains 0 to 10 weight percent fatty alcohols based on the weight of fatty acid esters, The shell contains the reaction product of an isocyanate component and an amine compound. The isocyanate component comprises, based on the weight of the phase change material component, (B1) 1 to 20 weight percent of an aliphatic isocyanate having at least two isocyanate groups, and (B2) 1 to 20 weight percent of an aromatic isocyanate having at least two isocyanate groups, wherein the weight ratio of the aliphatic isocyanate to the aromatic isocyanate is in the range of 8.5:1.5 to 1.5:8.5. The composition comprises an amine compound containing at least two amino functional groups selected from primary amino groups, secondary amino groups, or combinations thereof, and the amine compound is present in an amount that provides a molar ratio of the total primary and secondary amino groups to the isocyanate group in the range of 0.3:1 to 1.5:1.

[0008] In a second embodiment, the present invention is a method for preparing the composition of the first embodiment. This method is (I) To provide an oil phase mixture, the oil phase mixture is (A) A phase change material component, (A1) Fatty acid ester, (A2) 1 to 6 weight percent of fatty acids having 10 to 18 carbon atoms, based on the weight of fatty acid esters, and (A3) Phase change material components comprising 0 to 10 weight percent fatty alcohols based on the weight of fatty acid esters, (B) An isocyanate component comprising, based on the weight of the phase change material component, (B1) 1 to 20 weight percent of an aliphatic isocyanate having at least two isocyanate groups, and (B2) 1 to 20 weight percent of an aromatic isocyanate having at least two isocyanate groups, wherein the weight ratio of the aliphatic isocyanate to the aromatic isocyanate is in the range of 8.5:1.5 to 1.5:8.5, to provide an oil phase mixture. (II) To provide an aqueous amine solution containing an amine compound and water, wherein the amine compound comprises at least two amino functional groups selected from primary amino groups, secondary amino groups, or combinations thereof, and the amine compound is present in an amount that provides a molar ratio of the total primary and secondary amino groups in the amine compound to the total isocyanate groups in the isocyanate component, in the range of 0.3:1 to 1.5:1. (III) Adding the oil phase mixture to the amine aqueous solution while stirring to form a reaction mixture, (IV) Maintaining the reaction mixture obtained from step (III) for the period until microcapsules are obtained.

Brief Description of the Drawings

[0009] [Figure 1] This is an optical microscope photograph of a dispersion of the microcapsules of IE1 of the present invention described below, taken at room temperature (20 - 23°C). [Figure 2] This is an optical microscope photograph of a dispersion of the microcapsules of IE3 of the present invention described below, taken at room temperature. [Figure 3] This is a scanning electron microscope (SEM) image of a cross-section of the microcapsules of IE3 of the present invention described below.

Embodiments for Carrying Out the Invention

[0010] The test method refers to the most recent test method on the priority date of this document when the date is not indicated together with the number of the test method. References to test methods include both references to the test society and the test method number. In this specification, the following abbreviations and identifiers of test methods are applicable. ISO refers to the International Organization for Standards.

[0011] Products identified by trade names refer to the compositions available under those trade names on the priority date of this document.

[0012] 「and / or」 means 「and, or as an alternative」. All ranges include endpoints unless otherwise indicated.

[0013] Unless otherwise specified, all percentage (%) values are weight percentages based on the weight of the composition.

[0014] 「Interfacial polymerization」 is a process in which the microcapsule walls of polymers such as polyurea are formed at the interface between two immiscible phases by a polycondensation reaction.

[0015] "Phase change material" refers to a substance that can release or absorb energy during a phase transition to provide heat or cooling.

[0016] "Bio-based phase change material" (BPCM) typically refers to a phase change material derived from raw materials such as plants, vegetable oils (e.g., soybean oil, coconut oil, and palm oil), animal fats such as tallow, animal oils and fats, plant waxes, or combinations thereof.

[0017] "Microencapsulation" refers to a process of encapsulating solid, liquid, or gaseous materials into fine particles having a diameter in the range of 1 micrometer (μm) to 1000 μm.

[0018] A microcapsule is a particle having a core surrounded by a shell and having a diameter of 1 μm to 1000 μm. The composition of the shell is different from that of the core. The shell material, in this specification, when the microcapsule is formed by a combination of the shell material and the core material, the microcapsule accommodates some volume of the composition of the core particles, and based on the total surface area of the surface of the microcapsule, when at least 50% or more of the surface area of the microcapsule consists of the composition of the shell material, the core particles are said to be "surrounded".

[0019] The present invention relates to a composition constituting a microcapsule. The microcapsule includes a core and a shell (also known as a "wall") surrounding (or encapsulating) the core. The core of the microcapsule may include and may consist of the phase change material components described below and optionally the inorganic fillers described below. The shell of the microcapsule may include and may consist of the reaction product of the isocyanate component and the amine compound described below and optionally the inorganic fillers described below.

[0020] The phase change material components useful in the present invention ("PCM components") may include, or consist of, one or more fatty acid esters as the first PCM(A1), one or more fatty acids as the second PCM(A2), and optionally one or more fatty alcohols as the third PCM(A3), and / or additional PCMs other than (A1), (A2), and (A3) as the fourth PCM(A4), all of which are described below herein.

[0021] The fatty acid esters (A1) useful in the present invention are generally produced by the esterification reaction of an alcohol, diol, and / or polyol having one hydroxy(-OH) group with a fatty acid, and include, for example, esters of alcohols such as methanol, ethanol, isopropanol, propanol, butanol, isobutanol, pentanol, hexanol, and cyclohexanol; mono-, di-, or triglycerides of glycerol, esters of pentaerythritol, polyesters of polyhydric alcohols, esters or diesters of ethylene glycol; or mixtures thereof. Preferably, the fatty acid ester (A1) is a fatty acid ester of one or more alcohols. Fatty acids useful for forming the fatty acid ester (A1) may be saturated or unsaturated fatty acids having 10 to 18 carbon atoms and one carboxyl functional group (-COOH). Specific examples of fatty acids for preparing fatty acid esters (A1) include decanoic acid, lauric acid, myristic acid, palmitic acid, oleic acid, stearic acid, hydrates or hydrogenated acids of any of the aforementioned acids, and / or combinations of two or more of these.

[0022] In the present invention, useful fatty acid esters (A1) include fatty acid methyl esters, fatty acid ethyl esters, fatty acid propyl esters, fatty acid butyl esters, or mixtures thereof, preferably fatty acid methyl esters, fatty acid ethyl esters, or combinations thereof, more preferably fatty acid methyl esters. Specific examples of fatty acid esters include methyl palmitate, methyl laurate, methyl stearate, methyl myristate, ethyl laurate, ethyl palmitate, isopropyl stearate, isopropyl palmitate, butyl stearate, butyl palmitate, cetyl palmitate, or mixtures thereof. Preferably, fatty acid ester (A1) is one or any combination of two or more of the following fatty acid esters: methyl laurate, methyl palmitate, methyl stearate, ethyl laurate, ethyl palmitate, and butyl stearate. Preferably, fatty acid ester may be methyl palmitate, or a mixture of ethyl palmitate and methyl palmitate.

[0023] The fatty acid ester (A1) may be present in a concentration of 86% to 99% by weight based on the weight of PCM component (A), and may be 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 94% or more, 95% or more, 96% or more, and even 96.5% or more by weight, while also being 99% or less by weight, 98.5% or less, 98.4% or less, 98% or less by weight, or even 96.5% or less by weight, preferably 94% to 99% by weight. The weight of the phase change material component also refers to the total weight of PCM in the microcapsule (for example, the combined weight of the phase change materials (A1), (A2), (A3), and (A4) described below, if present).

[0024] In the present invention, the PCM component (A) useful is (A2) fatty acid. The fatty acid may include saturated or unsaturated fatty acids having 10 to 18 carbon atoms and 1 -COOH group. One or more of the fatty acids may be used. Examples of suitable fatty acids (A2) include those mentioned above for preparing fatty acid esters. Particularly suitable examples of fatty acids (A2) include palmitic acid (hexadecanoic acid), lauric acid (dodecanoic acid), stearic acid (octadecanoic acid), myristic acid (tetradecanoic acid), decanoic acid, or mixtures thereof.

[0025] The fatty acid (A2) may be present in a concentration of 1.0% to 6.0% by weight, based on the weight of the fatty acid ester (A1), and may be 1.0% or more, 1.2% or more, 1.4% or more, 1.5% or more, 1.6% or more, 2% or more, 2.2% or more, and even 2.4% or more by weight, while also being 6% or less by weight, 5.5% or less, 5% or less, 4.5% or less, 4% or less by weight, 3.5% or less by weight, 3.2% or less by weight, 3% or less by weight, 2.5% or less by weight, and even 2.4% or less by weight, preferably 1.0% to 3.2% or 1.2% to 2.4% by weight. The concentration of fatty acid (A2) is important for both emulsification and polymerization involved in the method of preparing PCM microcapsules in order to obtain the desired particle size distribution and good encapsulation properties (e.g., good thermal stability) described below.

[0026] The PCM component (A) useful in the present invention may or may not contain (A3) a fatty alcohol. A fatty alcohol refers to a linear primary alcohol containing 4 to 26 carbon atoms or 6 to 22 carbon atoms, which may be derived from natural oils and fats. A fatty alcohol may have one hydroxyl group. Preferred examples of fatty alcohols include 1-decanol, 1-dodecanol, 1-tetradecanol, 1-hexadecanol, 1-octadecanol, or mixtures thereof. The fatty alcohol (A3) may be present in an amount of 0 to 10% by weight based on the weight of the fatty acid ester (A1), and may be 0% or more, 0.1% or more, 0.5% or more, 1% or more, 2% or more, 3% or more, and even 4% or more by weight, while also being 10% or less by weight, 8% or less, 6% or less by weight, 5% or less by weight, 3% or less by weight, 1% or less by weight, 0.5% or less by weight, 0.1% or less by weight, or even 0% by weight, preferably 0 to 5% or 0 to 3% by weight.

[0027] The above fatty acid esters (A1), fatty acids (A2), and fatty alcohols (A3) are bio-based phase change materials and may be derived from renewable resources such as animal fat sources (e.g., lard or beef tallow), poultry fat sources, soybean oil, rapeseed oil, peanut oil, vegetable oil, yellow fats, or combinations of two or more thereof. The concentration of bio-based PCM in the PCM components may range from 95% to 100% by weight, based on the weight of the PCM components, and may be 96% or more, 97% or more, 98% or more, 99% or more, or even 100% by weight.

[0028] The PCM component (A) useful in the present invention may include, and preferably substantially does not include, additional organic phase-changing materials (A4) other than (A1), (A2), and (A3) above. The additional organic phase-changing materials (A4) may include paraffinic hydrocarbons (also known as "linear alkanes") such as N-dodecane, N-tridecane, N-tetradecane, N-pentadecane, N-hexadecane, N-heptadecane, N-octadecane, or mixtures thereof. "Substantially absent" means that the concentration of the additional organic phase-changing material (e.g., paraffinic hydrocarbon) is at most 5% by weight, based on the weight of the PCM component, and may be less than 5% by weight, less than 4% by weight, less than 3% by weight, less than 2% by weight, less than 1% by weight, less than 0.1% by weight, or even zero.

[0029] Preferably, the PCM component comprises or consists of a fatty acid ester (A1) selected from methyl palmitate, methyl laurate, methyl stearate, ethyl laurate, ethyl palmitate, or a mixture thereof; 1.2% to 2.4% by weight of a fatty acid (A2) selected from lauric acid, palmitic acid, or a mixture thereof, based on the weight of the fatty acid ester; and 0% to 5.0% by weight of a fatty alcohol (A3).

[0030] Preferably, the PCM components are (ai)~(a-vi), i.e., (ai) Fatty acid ester (A1) is methyl palmitate, and fatty acid (A2) is palmitic acid. (a-ii) The fatty acid ester (A1) is methyl palmitate, the fatty acid (A2) is palmitic acid, and the fatty alcohol (A3) is selected from the group consisting of tetradecanol, dodecanol, and mixtures thereof. (a-iii) The fatty acid ester (A1) is methyl laurate, and the fatty acid (A2) is lauric acid. (a-iv) Fatty acid ester (A1) is methyl stearate, and fatty acid (A2) is palmitic acid. (av) Fatty acid ester (A1) is ethyl laurate, and fatty acid (A2) is lauric acid, and (a-vi) The fatty acid ester (A1) is selected from one of the following based on the total weight of the fatty acid ester: a mixture of 10% to 100% by weight of ethyl palmitate and 0% to 90% by weight of methyl palmitate, and the fatty acid (A2) is palmitic acid.

[0031] The core of the PCM microcapsule may contain bio-based PCM at a concentration of 95-100% based on the total weight of PCM in the core, and may be 95% or more by weight, 96% or more by weight, 97% or more by weight, 98% or more by weight, 99% or more by weight, or even 100% by weight.

[0032] The shell of the PCM microcapsule of the present invention contains, or consists of, a reaction product of an isocyanate component and an amine compound, obtained by polycondensation reaction between the isocyanate component and the amine compound, for example, to form polyurea by interfacial polymerization. The isocyanate component useful in the present invention includes a mixture of (B1) one or more aliphatic isocyanates and (B2) one or more aliphatic isocyanates. "Aliphatic isocyanate" refers to an isocyanate containing an isocyanate (NCO) group bound to an aliphatic residue. The aliphatic isocyanate (B1) useful in the present invention has at least two NCO groups. The average NCO functional value of the aliphatic isocyanate can be at least 2, 2 or more, 2.5 or more, or even 2.7 or more, and at the same time generally 4 or less, and also 3.5 or less, 3 or less, 2.8 or less, or even 2.7 or less. Aliphatic isocyanates may include aliphatic diisocyanates, their dimers, their trimers, or combinations thereof. Aliphatic diisocyanates are X 1 (NCO)2(wherein, X 1The structure may be a linear or branched alkylene residue having typically 3 to 16 carbon atoms or 4 to 12 carbon atoms, or a cycloalkylene residue having typically 4 to 18 carbon atoms or 6 to 15 carbon atoms. Examples of suitable aliphatic isocyanates include aliphatic diisocyanates, such as tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), cyclohexane diisocyanate, methylcyclohexane diisocyanate, ethylcyclohexane diisocyanate, propylcyclohexane diisocyanate, methyldiethylcyclohexane diisocyanate, propane diisocyanate, butane diisocyanate, pentane diisocyanate, hexane diisocyanate, heptane diisocyanate, octanedine diisocyanate, and nona Diisocyanate, 1,12-dodecane diisocyanate, 2-methyl-1,5-pentamethylene diisocyanate; 4-isocyanatomethyl-1,8-octanediisocyanate (TIN), decanediisocyanate, undecane diisocyanate and dodecane diisocyanate, isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (HMDI), 1,4-cyclohexane diisocyanate and 1,3-bis(isocyanatomethyl)cyclohexane; diisocyanate dicyclohexylmethane (H 12Examples include MDI, 2-methylpentane diisocyanate (MPDI), 2,2,4-trimethylhexamethylene diisocyanate / 2,4,4-trimethylhexamethylene diisocyanate (TMDI), norbornane diisocyanate (NBDI); xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate; dimers of these aliphatic diisocyanates; trimers of these aliphatic diisocyanates such as HDI trimers; homopolymers of these such as HDI homopolymers and IPDI homopolymers; adducts, e.g., isophorone diisocyanate adducts, or mixtures thereof. A mixture of two or more aliphatic isocyanates may be used, provided that the average functional value of these aliphatic isocyanates is 2 or greater. Preferably, the aliphatic isocyanates are selected from the group consisting of IPDI, HDI, HDI trimers, IPDI trimers, and mixtures thereof.

[0033] Aliphatic isocyanates may be present in amounts ranging from 1% to 20% by weight, based on the weight of the PCM components, and may be 1% or more, 3% or more, 5% or more, 6% or more, 7% or more, 8% or more, 9% or more by weight, and at the same time, 20% or less by weight, 18% or less by weight, 15% or less by weight, 14% or less by weight, 12% or less by weight, or even 10% or less by weight.

[0034] The aromatic isocyanate (B2) useful in the present invention contains at least two NCO groups. The average NCO value of the aromatic isocyanate can be at least 2, 2 or more, 2.5 or more, or even 2.7 or more, and at the same time generally 4 or less, and also 3.5 or less, 3 or less, 2.8 or less, or even 2.7 or less. The aromatic isocyanate is X 2 (NCO)2(wherein, X 2The aromatic isocyanates may include aromatic diisocyanates having the structure of an aromatic hydrocarbon radical having 6 to 15 carbon atoms, their dimers, their trimers, or combinations thereof. Examples of suitable aromatic isocyanates include diphenylmethane diisocyanate (MDI), e.g., 2,2'-MDI, 2,4'-MDI, 4,4'-MDI, or mixtures thereof; 1,3- and 1,4-phenylenediisocyanate, 1,5-naphthylene diisocyanate, toluene diisocyanate (TDI), e.g., 2,6-TDI, 2,4-TDI, or mixtures thereof; 3,3'-dimethyl-4,4'-biphenyl diisocyanate (TODI), phenyl Examples include diphenyl diisocyanates; carbodiimide-modified diphenylmethane diisocyanates, including carbodiimide-modified isomers of the above MDI such as carbodiimide-modified 4,4'-MDI and polycarbodiimide-modified diphenylmethane diisocyanate; polymer derivatives of the above monomer diisocyanates, such as polymer methylene diphenyl diisocyanates ("polymer MDI"), which contain polymethylene polyphenyl isocyanate; or combinations thereof. A mixture of 2,4'-MDI and 4,4'-MDI may also be used. A suitable commercially available carbodiimide-modified MDI is ISONATE® 143L polycarbodiimide-modified MDI, available from The Dow Chemical Company (ISONATE is a trademark of The Dow Chemical Company). Polymer MDI may be a mixture of diphenylmethane diisocyanate and polymethylene polyphenyl isocyanate.

[0035] A mixture of two or more aromatic isocyanates can be used, provided that the average functional value of these aromatic isocyanates is 2 or higher. Preferably, aromatic isocyanate (B2) is selected from the group consisting of polymethylene polyphenyl isocyanate, methylene diphenyl diisocyanate, polycarbodiimide-modified MDI, and mixtures thereof. The average NCO functional value of polymethylene polyphenyl isocyanates useful in the present invention may be 2 to 4, and may be 2 or higher, 2.2 or higher, 2.3 or higher, and even 2.5 or higher, while also being 4 or lower, and also 3.5 or lower, 3 or lower, 2.8 or lower, or even 2.7 or lower. The number-average molecular weight of polymethylene polyphenyl isocyanate, when measured by gel permeation chromatography (GPC), may be 250 to 400, and may be 250 or higher, 270 or higher, and even 290 or higher, while also being 400 or lower, and also 380 or lower, or even 360 or lower. Suitable commercially available polymethylene polyphenyl isocyanates include PAPI® PB-219, PAPI 27, PAPI 20, PAPI 580N, VORANATE® M229, VORANATE M220, VORANATE 290, VORANATE M595, and VORANATE M600 isocyanates, all of which are available from The Dow Chemical Company (PAPI and VORANATE are trademarks of The Dow Chemical Company).

[0036] A prepolymer of the above-mentioned monomer aliphatic or aromatic isocyanate, comprising at least two isocyanate groups (used interchangeably with "isocyanate prepolymer"), can be used. The isocyanate prepolymer can be obtained by reacting the above-mentioned monomer isocyanate with an isocyanate-reactive compound known in the art. The average NCO functional value of the isocyanate prepolymer may be 3 or higher.

[0037] Aromatic isocyanate (B2) may be present in amounts of 1% to 20% by weight based on the weight of the PCM component, and may be 1% or more, 3% or more, 5% or more, 6% or more, 7% or more, 8% or more, 9% or more by weight, and at the same time 20% or less by weight, and may also be 18% or less by weight, 15% or less by weight, 14% or less by weight, 12% or less by weight, or even 10% or less by weight.

[0038] The aliphatic isocyanate (B1) and aromatic isocyanate (B2) may be in amounts that provide a weight ratio of aliphatic isocyanate to aromatic isocyanate (also called the "B1 / B2 ratio") in the range of 8.5:1.5 to 1.5:8.5, 7:3 to 3:7, 6:4 to 4:6, 5:5 to 3:7, or even further in the range of 4:6 to 5:5, preferably in the range of 4:6 to 5:5.

[0039] Preferably, the isocyanate component (B) useful in the present invention is (bi) to (b-iii) below, namely, (bi) A mixture of IPDI and polymethylene polyphenyl isocyanate, wherein the weight ratio of IPDI to polymethylene polyphenyl isocyanate is in the range of 3:7 to 7:3, preferably 4:6 to 6:4, and more preferably 4:6 to 5:5. (b-ii) A mixture of HDI trimer and polymethylene polyphenyl isocyanate, wherein the weight ratio of HDI trimer to polymethylene polyphenyl isocyanate is in the range of 3:7 to 7:3, preferably 4:6 to 6:4, and more preferably 4:6 to 5:5, and (b-iii) A mixture of an IPDI trimer and a polymethylene polyphenyl isocyanate, wherein the weight ratio of the IPDI trimer to the polymethylene polyphenyl isocyanate is in the range of 3:7 to 7:3, preferably 4:6 to 6:4, and more preferably 4:6 to 5:5, comprising one of these mixtures.

[0040] The amine compounds useful in the present invention have at least two or three amino functional groups selected from primary amino groups (-NH2), secondary amino groups (-NH-), or combinations thereof. The amine compounds may include two or more -NH2 groups, two or more -NH- groups, or a combination of at least one -NH2 group and at least one -NH- group. The amine compounds are useful as curing agents and typically contain up to eight carbon atoms, and are therefore usually water-soluble amines. The amine compounds usually have a molecular weight of 32 to 500 grams / mol (g / mol) or 60 to 300 g / mol. The amine compounds may be aromatic polyamines, aliphatic polyamines, or mixtures thereof. "Aromatic polyamine" refers to an organic compound containing an aromatic ring bonded to an amine. Examples of suitable aromatic polyamines include 2,4- and / or 2,6-toluenediamine (toluene diamine, TDA), 4,4'-, 2,4'- and 2,2'-diphenylmethanediamine (methane diamine, MDA), or mixtures thereof. "Aliphatic polyamine" refers to a polyamine containing two or more primary or secondary amino groups separated by aliphatic hydrocarbon chains, which may be linear or branched. Preferably, the amine compound contains or consists of one or more aliphatic polyamines.Suitable examples of aliphatic polyamines include diamines, e.g., diaminoethane, diaminopropane, diaminobutane; diaminohexanes, e.g., 1,6-diaminohexane and trimethylhexanediamine; amino-3-aminomethyl-3,5,5-trimethylcyclohexane (isophoronediamine, IPDA); 2,4- or 2,6-diamine-1-methylcyclohexane (methylecyclohexane); 1,3- and / or 1,4-bis(aminomethyl)cyclohexane; 4,4'-diaminodicyclohexylmethane; 1,4-diaminocyclohexane; piperazine; 2,5-dimethylpiperazine; triamines, e.g., diethylenetriamine (DETA); 1,3,5-cyclohexanetriamine; 1,2,3-propanetriamine; and 1,8-diamino-4-aminomethyloctane; triethylenetetramine; tetraethylenepentamine; pentaethylenehexamine; or mixtures thereof. Preferably, the amine compound is a triamine. More preferably, the amine compound is selected from the group consisting of DETA, 1,3,5-cyclohexanetriamine, 1,2,3-propanetriamine, or a mixture thereof.

[0041] The amine compound is present in an amount sufficient to ensure that the molar ratio (hereinafter also referred to as the "amino / NCO ratio") of the total primary and secondary amino groups in the amine compound to the total -NCO groups in the isocyanate component is in the range of 0.3:1 to 1.5:1, and may be 0.3:1 or greater, 0.4:1 or greater, 0.5:1 or greater, 0.7:1 or greater, 0.8:1 or greater, 0.9:1 or greater, and even 1:1, while simultaneously being 1:5:1 or less, and also 1.4:1 or less, 1.3:1 or less, 1.2:1 or less, 1.1:1 or less, or even 1:1 or less, preferably 0.9:1 to 1:1.1.

[0042] Furthermore, the microcapsule shell may contain reaction products of isocyanate and water, especially when the amino / NCO ratio is less than 1. The microcapsule core and / or shell may independently contain or not contain one or more inorganic fillers. Suitable inorganic fillers include, for example, natural calcium carbonate including chalk, calcite and marble, synthetic carbonates, magnesium and calcium salts, dolomite, magnesium carbonate, zinc carbonate, lime, magnesia, barium sulfate, barite, calcium sulfate, silica, magnesium silicate, talc, wollastonite, clay and aluminum silicate, kaolin, mica, oxides or hydroxides of metals or alkaline earths, magnesium hydroxide, iron oxide, zinc oxide, glass or carbon fiber or powder, or powders or mixtures thereof. Preferably, inorganic fillers include CaCO3, talc, mica, SiO2, TiO2, kaolin, coal dust powder, sepiolite powder, attapulgite powder, montmorillonite, or mixtures thereof. The inorganic filler in the PCM microcapsules may be present in a total concentration of 0 to 30% by weight, based on the weight of the PCM components, and may be 0% or more, 2% or more, 5% or more, 8% or more, 10% or more, 12% or more, and even 15% or more by weight, while also being 30% or less by weight, and also 28% or less by weight, 25% or less by weight, 22% or less by weight, 20% or less by weight, or even 18% or less by weight, preferably 2% to 30% by weight, 5% to 20% by weight, or 8% to 15% by weight.

[0043] The microcapsules of the present invention may or may not contain an emulsifier (described later in the Method section). The concentration of the emulsifier may be less than 0.1% by weight, and may be 0.05% by weight or less, 0.001% by weight or less, or even zero, based on the weight of the microcapsules.

[0044] The average weight ratio of the core to the shell of the microcapsule of the present invention (hereinafter also referred to as the "core / shell ratio") may be in the range of 2.0:1 to 10:1, 3.0:1 to 9:1, 3.5:1 to 8:1, 4.0:1 to 7:1, 4.0:1 to 6.2:1, 4.0:1 to 5.5:1, preferably 4.0:1 to 5.0:1. The core / shell ratio can be determined by analyzing the thermal enthalpy of the PCM microcapsule using differential scanning calorimetry (DSC), for example, by using a DSC-Q2000 (TA Instruments) at 1 to 10°C (°C / min) for heating and cooling at 0 to 60°C / min.

[0045] The D90 particle size of the microcapsules of the present invention may be in the range of 10 micrometers (μm) to 500, and may be 10 μm or more, 20 μm or more, 30 μm or more, 50 μm or more, 60 μm or more, 80 μm or more, 90 μm or more, and even 100 μm or more, while also being a D90 of 500 μm or less, and may also be 400 μm or less, 300 μm or less, 250 μm or less, 220 μm or less, or even 200 μm or less, preferably 30 μm to 250 μm. The D10 particle size of the microcapsules of the present invention may be in the range of 1 μm to 50 μm, and may be 1 μm or more, 2 μm or more, 3 μm or more, 5 μm or more, 6 μm or more, 8 μm or more, 9 μm or more, and even 10 μm or more, while simultaneously being 50 μm or less, and also 40 μm or less, 30 μm or less, 25 μm or less, 22 μm or less, or even 20 μm or less, preferably 5 μm to 30 μm. D10 and D90 refer to the volume-based particle size distribution, and indicate that the particle diameters corresponding to 10% and 90% of the distribution are below these diameters, respectively. The diameter can be measured according to focused beam reflectance measurement techniques (further details are provided in the Examples section below).

[0046] The microcapsules of the present invention may comprise a PCM and a plurality of different phases or layers formed by the reaction products of an amine compound and an isocyanate component. The microcapsules have a core-shell structure. The structure of the PCM microcapsules can be characterized by SEM. Figure 3 is a representative SEM image of a cross-section of the PCM microcapsule of the present invention (IE 3 described below), showing the core-shell structure of the microcapsule.

[0047] The composition of the present invention may be an aqueous dispersion or powder containing microcapsules. The composition containing microcapsules exhibits good thermal stability, which indicates good encapsulation density. "Good thermal stability" means that when heated at 105°C for 24 hours (hereinafter also referred to as "thermal aging"), the composition exhibits a weight loss of less than 20% by weight, preferably less than 10% by weight, less than 9% by weight, less than 8% by weight, less than 7% by weight, less than 6% by weight, and more preferably less than 5% by weight, relative to the weight of the microcapsules (before thermal aging), as measured according to the thermal stability test of microcapsules described in the Examples section below.

[0048] A method for preparing the composition of the microcapsules of the present invention may include the steps of (I) providing an oil phase mixture, (II) providing an aqueous amine solution, (III) adding the oil phase mixture to the aqueous amine solution while stirring, and (IV) maintaining the reaction mixture for the period until microcapsules are obtained.

[0049] An oil phase mixture useful in the present invention may contain the above-mentioned PCM component (A), the above-mentioned isocyanate component (B), and optionally the above-mentioned inorganic filler. The oil phase mixture may or may not contain the above-mentioned inorganic filler. In step (I), the oil phase mixture can be prepared by mixing the PCM components (e.g., (A1), (A2), and optionally (A3) and (A4)) with the isocyanate component (B) and optionally the inorganic filler. Preferably, the PCM components are first subjected to a temperature high enough to melt the PCM (e.g., methyl palmitate, ethyl palmitate, and palmitic acid) before the addition of the remaining components in the oil phase mixture. The temperature for melting the PCM may be in the range of 30 to 70°C, depending on the melting point of the PCM. Preferably, the temperature of the oil phase mixture in step (I) is in the range of 40 to 60°C. If used, the inorganic filler may be included in the oil phase mixture in step (I). When inorganic fillers are used, the oil phase mixture may further contain one or more dispersants. Preferably, the oil phase mixture includes a blend of one of the above PCM components (ai) to (a-vi) with the above isocyanate component (bi), a blend of one of the above PCM components (ai) to (a-vi) with the above isocyanate component (b-ii), or a blend of one of the above PCM components (ai) to (a-vi) with the above isocyanate component (b-iii), each blend which may or may not contain the above inorganic fillers. The concentrations of each component in the oil phase mixture are the same as those described in the section on PCM microcapsules.

[0050] The amine aqueous solution useful in the present invention contains the above amine compound and water. The amount of the amine compound used is an amount to provide the same amino / NCO ratio as described in the section of the above PCM microcapsules. The water in the amine aqueous solution typically provides an aqueous phase containing an amine compound that reacts with the isocyanate in the oil phase, and is present in an amount sufficient to control the viscosity of the mixture of the amine aqueous solution and the oil phase mixture and give the resulting microcapsules a desirable particle size distribution. For example, the water may be present in an amount of at least 3 times the total weight of the oil phase mixture, and may be 3.1 times or more, 3.2 times or more, 3.3 times or more, 3.4 times or more, or even 4 times or more. In step (II) of the method, the amine aqueous solution can be prepared by mixing the amine compound with water. The amine aqueous solution can be further heated to a temperature in the range of 30 to 80°C, and can be 40 to 70°C or 50 to 70°C, before the addition of the oil phase mixture. Desirably, the temperature of the amine aqueous solution in step (II) is in the range of 50 to 70°C.

[0051] The oil phase mixture and / or the amine aqueous solution used for preparing the PCM microcapsules may not substantially contain an emulsifier. Surprisingly, when a specific amount of the above fatty acid (A2) is used in combination with the fatty acid ester (A1), a self-emulsifying PCM component essential for good encapsulation of the PCM using the method of the present invention can be obtained. The emulsifier can be cationic, anionic, or nonionic. Examples of the emulsifier include nonionic surfactants such as sulfates of ethoxylated phenols such as secondary alcohol ethoxylate, poly(oxy-1,2-ethanediyl), α-sulfo-ω-(nonylphenoxy) salts; alkali metal fatty acid salts such as alkali metal oleates, alkali metal stearates, alkali metal palmitates; alkali metal C 12 ~C 16 alkyl sulfates such as alkali metal lauryl sulfates; amine C 12 ~C 16 alkyl sulfates such as amine lauryl sulfates, more preferably triethanolamine lauryl sulfate; alkali metal C 12 ~C 16Alkylbenzenesulfonates, such as branched-chain and linear sodium dodecylbenzenesulfonate; amine C 12 ~C 16 Alkylbenzenesulfonates, e.g., triethanolamine dodecylbenzenesulfonate; anionic and nonionic fluorocarbon emulsifiers, e.g., fluorinated C4-C 16 Alkyl esters and alkali metals C4-C 18 Perfluoroalkyl sulfonates; organosilicon emulsifiers, such as modified polydimethylsiloxane. "Substantially absent" means less than 0.1% by weight, based on the total solids weight of the oil phase mixture and the amine aqueous solution, and may be 0.05% by weight or less, 0.001% by weight or less, or even zero.

[0052] In step (III) of this method, the oil phase mixture is added to the amine aqueous solution with stirring to form a reaction mixture. The oil phase mixture may be added at temperatures in the range of 30-80°C, 10-75°C, 20-70°C, 30-70°C, or even 40-70°C. While the oil phase mixture is being added, the amine aqueous solution may be at temperatures in the range of 30-80°C, 40-70°C, or even 50-70°C. Preferably, if the (A1) fatty acid ester is methyl palmitate, ethyl palmitate, or a mixture thereof, the oil phase mixture is added to the amine aqueous solution at a temperature of 50-70°C, while the amine aqueous solution is at a temperature of 50-70°C.

[0053] In step (IV) of this method, the reaction mixture is maintained at a temperature typically in the range of 30–80°C, 40–70°C, or 50–70°C until microcapsules are obtained. The time must be sufficient for interfacial polymerization to be completed, for example, in the range of 0.1 to 5 hours, 0.5 to 4 hours, or 1 to 3 hours. After the reaction, the aqueous dispersion of the obtained microcapsules can be cooled to room temperature. In this specification, “aqueous” dispersion means that the particles are dispersed in an aqueous medium. In this specification, “aqueous medium” means water and, based on the weight of the medium, 0–30% by weight of a water-miscible compound, such as an alcohol, glycol, glycol ether, glycol ester, or a mixture thereof. The resulting aqueous dispersion may have a solid content of 5%–60% by weight, 10%–50% by weight, or 20%–40% by weight, based on the weight of the aqueous dispersion.

[0054] One, two or more, or all of the above steps (I) to (IV) in this method, particularly step (III), can be carried out by standard power mixing provided by an overhead mixer having 3 cm stirring blades at a low speed, i.e., less than 1500 revolutions per minute (rpm), which may be 100 to 1400 rpm, 200 to 1000 rpm, less than 1000 rpm, or 300 to 700 rpm.

[0055] The method of the present invention may further include the step of (V) drying an aqueous dispersion of microcapsules to obtain microcapsule powder (i.e., solid microcapsules). Drying can be carried out by spray drying. Preferably, the aqueous dispersion obtained from step (IV) is filtered to obtain a microcapsule paste, which is further dried. The filtering step also yields a filtrate that can be recycled to step (III) as an oil phase mixture, and the amine aqueous solution may be substantially free of emulsifiers.

[0056] The method of the present invention does not require a pre-emulsification step before step (III), and preferably does not require a pre-emulsification step. In this specification, a pre-emulsification step refers to any approach that can emulsify the oil phase mixture, for example, by using the emulsifiers described above and / or by high-shear mixing (i.e., mixing at a mixing speed greater than 1500 rpm). The method of the present invention provides a self-emulsifying approach for microencapsulating PCM.

[0057] The oil phase mixture and amine aqueous solution used in this method may be substantially free of organic solvents. The substantially absence of solvent means that the method for preparing microencapsulated PCMs does not involve (i.e., does not include) extra steps for solvent removal, such as solvent stripping.

[0058] Compositions containing microcapsules obtained by this method can be used in a wide range of applications, including building and construction, bedding, textiles, foams, automobiles, heating, ventilation, and air conditioning (HVAC), and batteries and electronic equipment. [Examples]

[0059] Herein, some embodiments of the present invention are described in the following examples. Unless otherwise specified, wt% refers to a weight percentage relative to the weight of the composition. Table 1 lists materials for use in the microencapsulation of the phase change materials (PCMs) described below in this specification. Note: PAPI, ISONATE, and TERGITOL are trademarks of The Dow Chemical Company.

[0060] [Table 1]

[0061] NCO content refers to the weight percentage of NCO groups relative to the weight of the isocyanate compound, as measured according to ISO 14896's determination of isocyanate content in polyurethane raw materials.

[0062] Examples of the present invention (Inventive Examples, IE) 1-14 and comparative examples (Comparative Examples, CE) 1-15 The formulations of these samples are shown in Tables 2 and 3, and the amount of each component is reported in grams (grams, g). The samples were prepared using an SFJ 400 Multi / Functional Lab Mixer equipped with a hot water circulation bath for mixing the components together.

[0063] General procedure for sample preparation First, PCM (A1), (A2), and (A3) if used were melted in an oven at 50-70°C to obtain molten PCM ("pre-melting step"). Next, other components of the oil phase mixture (including isocyanates (B1) and (B2), surfactants, and fillers if used) were added to the molten PCM obtained above, thereby forming a high-temperature oil phase mixture. It should be noted that when preparing the IE 8, IE 10, CE 12, and CE 13 samples, the step of pre-melting the PCM was omitted, and the oil phase mixture was prepared by mixing all the components of the oil phase mixture.

[0064] Secondly, DETA, deionized (DI) water, and a surfactant, if used, were mixed to form an amine aqueous solution (also called "DETA solution"), which was then heated to 50-70°C.

[0065] The oil phase mixture obtained above was directly poured into the amine aqueous solution obtained above while stirring at a mixing speed of 200 to 700 revolutions per minute (rpm). The resulting mixture was maintained at 50 to 70°C for 1 to 4 hours, and then cooled to room temperature to obtain an aqueous dispersion of PCM microcapsules. The aqueous dispersion of microcapsules was filtered using filter paper with pores of 3 to 5 μm to obtain a microcapsule paste, which was further dried overnight at 50°C to obtain a microcapsule powder.

[0066] The aqueous dispersion of the microcapsules obtained above was evaluated using the following test methods, and particle size distribution analysis was performed. Furthermore, the thermal stability was evaluated using the microcapsule powder obtained above.

[0067] Microcapsule particle size and particle size distribution The particle size and particle size distribution of PCM microcapsules in dispersion samples were analyzed using the ParticleTrack® G400 system with FBRM® (Focused Beam Reflectance Measurement) technology. The ParticleTrack G400 system includes a base unit and probe connected by a flexible outer conduit. The measurement range is 0.5–2000 μm.

[0068] The dispersion sample was placed in a beaker and maintained under stirring (200-250 rpm) during particle size measurement. A 14 mm probe was inserted vertically into the dispersion sample, and the measurement was started. Each sample was tested for 3-5 minutes. The D10 and D90 results were given at the end of the measurement.

[0069] Thermal stability of microcapsules Approximately 1 gram of PCM microcapsule powder was weighed using an analytical balance (recorded as "W1") and placed in a Thermo Scientific Heratherm OMH60 Advanced Lab Oven. The oven temperature was set to 105°C. The sample was placed in the oven and thermal aged at 105°C for 24 hours. After thermal aging, the sample was weighed again and recorded as "W2". The weight loss of the sample can be calculated as (W1-W2) / W1. A weight loss of less than 20% after thermal aging indicates good thermal stability, which indicates good density. Notably, aggregates, large clumps, and / or gels were observed with the naked eye in some CE samples, so the thermal stability properties of these samples were not measured and were therefore reported as "NA".

[0070] As shown in Table 2, IE1 to IE14 all provided good encapsulation of PCM, and all resulting PCM microcapsules met the requirements for good thermal stability (i.e., weight loss after thermal aging was less than 20%). For all IEs, when an oil phase mixture containing fatty acid esters (A1), fatty acids (A2), isocyanates (B1) and (B2), and optionally fatty alcohols (A3) and / or inorganic fillers in claimed amounts was added to an aqueous DETA solution, a well-dispersed dispersion (without coarse particles) was obtained. In IE1 to IE4, polymer MDI and IPDI were used together as isocyanates, and all resulting microcapsules met the thermal stability requirements. The IE5 microcapsule with a lower core / shell ratio (4:1) showed even better thermal stability than IE4 (core / shell ratio = 5:1). The IE6 microcapsule without inorganic fillers also showed slightly better thermal stability than IE3. IE7, which used a mixture of MDI and HDI trimer as the isocyanate component and methyl palmitate combined with palmitic acid as the PCM component, provided even better thermal stability than IE1-IE4, indicating that the combination of trifunctional HDI trimer and polymer MDI can contribute to the formation of a denser shell than the use of bifunctional IPDI and polymer MDI. IE9, which used methyl stearate combined with palmitic acid, formed the PCM core of the microcapsules. By blending with lauric acid, methyl laurate and ethyl laurate in IE8 and IE10 can be emulsified and encapsulated, respectively, based on the same process as in IE7. In this way, methyl laurate and ethyl laurate, combined with lauric acid, each formed the PCM core of the microcapsules formed in IE8 and IE10. In IE11, by blending with palmitic acid, ethyl palmitate can be emulsified and encapsulated, respectively, based on the same process as in IE7. In IE12, methyl palmitate was partially replaced with ethyl palmitate and blended with palmitic acid to form the PCM core of the resulting microcapsules.By blending with palmitic acid, the methyl palmitate-ethyl palmitate binary ester can be emulsified and encapsulated to form the core of the resulting microcapsule of IE12. The addition of palmitic acid allowed the blend of methyl palmitate with a low level of fatty alcohol (i.e., a ratio of methyl palmitate to tetradecanol of 96:4 by mass) to be well encapsulated and together form the core of the resulting microcapsule of IE13. IE14, with an amino / NCO molar ratio of 0.5, provided a microcapsule with the required thermal stability. All aqueous dispersions of the microcapsules obtained from IE1 to IE14 were observed under an optical microscope to confirm the formation of microcapsule particles for all IEs. Figures 1 and 2 are representative optical microscope images of IE1 and IE3, respectively. Some of these aqueous dispersions of the microcapsules of IE were further evaluated according to the particle size distribution test described above. The results are shown in Table 2.

[0071] As shown in Table 3, when a blend of methyl palmitate and isocyanates (B1) and (B2) was added to an aqueous DETA solution, no emulsion was formed in CE1. In CE2 and CE3, each oil phase mixture was prepared by simply mixing a nonionic secondary alcohol ethoxylate surfactant, methyl palmitate, and isocyanates (B1) and (B2). Adding such oil phase mixtures to an aqueous DETA solution formed an emulsion, which, after filtration, produced a thick, sticky mass. This indicates that a considerable amount of methyl palmitate was not encapsulated. In contrast to CE3, in CE4, nonionic and anionic surfactants (15-S-5 and SDBS) were first incorporated into the DETA-containing aqueous phase, followed by the addition of the oil phase mixture while mixing. CE4 did not yield an emulsion, but formed a large mass. In CE5 and CE6, sodium palmitate and ammonium palmitate were added to an aqueous DETA solution, respectively. Then, an oil phase mixture consisting of methyl palmitate, isocyanate, and a filler was added to the resulting aqueous solution while stirring. Methyl palmitate was not emulsified, and large aggregates were formed in both CE5 and CE6. All microcapsules obtained in CE7-CE9 and CE11 showed a weight loss of more than 20% after thermal aging. This indicates insufficient encapsulation. In CE7 and CE8, palmitic acid was incorporated into methyl palmitate at a lower concentration than the claimed amount. Methyl palmitate could not be emulsified, and large aggregates were formed in CE7. CE8 yielded an emulsion, but encapsulation was insufficient, and the thermal stability requirements could not be met. In CE9, when palmitic acid was incorporated into the oil phase mixture at a higher concentration than the claimed amount, the PCM was insufficiently encapsulated and could not meet the thermal stability requirements. CE10, which used IPDI as the sole isocyanate (and no aromatic isocyanates), was unable to encapsulate the PCM, and only large chunks were obtained.In CE11, PCM microcapsules were obtained using polymer MDI alone without aliphatic isocyanates, but the thermal stability shown was poor. In CE12-CE15, decanol, dodecanol, tetradecanol, and octadecane were used instead of methyl palmitate, respectively. However, none of them could be encapsulated. When the oil phase mixture was added to an aqueous DETA solution, viscous gel-like samples were obtained for all of CE12-CE15.

[0072] [Table 2] In Tables 2 and 3 below, "Solid Content" refers to the weight percentage of solids in the dispersion of encapsulated PCM relative to the weight of the dispersion. "Core / Shell Ratio" refers to the weight ratio of PCM components to polyurea formed by the reaction of isocyanate and amine. "Fatty Acid Weight %" refers to the weight percentage of fatty acids relative to the weight of fatty acid esters in the sample. "B1 / B2 Ratio" refers to the weight ratio of aliphatic isocyanate to aromatic isocyanate. "D10" and "D90" refer to the D10 and D90 particle sizes of PCM microcapsules in the dispersion, measured according to the above-described test method for particle size and particle size distribution of PCM microcapsules. "Weight % Loss" refers to the percentage of weight loss of PCM microcapsules after heating at 105°C for 24 hours, relative to the weight of PCM microcapsules (before heating), measured according to the above-described test method for thermal stability of microcapsules. "NA" means that data is not available.

[0073] [Table 3]

Claims

1. A composition comprising a microcapsule including a core and a shell, The core comprises a phase change material component, and the phase change material component is (A1) Fatty acid esters, (A2) Based on the weight of the fatty acid ester, 1 to 6 weight percent of a fatty acid having 10 to 18 carbon atoms, and (A3) comprising 0 to 10 weight percent of fatty alcohol based on the weight of the fatty acid ester, The aforementioned shell contains a reaction product of an isocyanate component and an amine compound. The isocyanate component comprises, based on the weight of the phase change material component, (B1) 1 to 20 weight percent of an aliphatic isocyanate having at least two isocyanate groups, and (B2) 1 to 20 weight percent of an aromatic isocyanate having at least two isocyanate groups, wherein the weight ratio of the aliphatic isocyanate to the aromatic isocyanate is in the range of 8.5:1.5 to 1.5:8.

5. A composition in which the amine compound comprises at least two amino functional groups selected from primary amino groups, secondary amino groups, or combinations thereof, and the amine compound is present in an amount that provides a molar ratio of the total primary and secondary amino groups to the isocyanate group in the range of 0.3:1 to 1.5:

1.

2. The composition according to claim 1, wherein the fatty acid ester (A1) is present at a concentration of 86 to 99 percent by weight based on the weight of the phase change material component.

3. The composition according to claim 1 or 2, wherein the fatty acid ester (A1) is selected from the group consisting of methyl palmitate, methyl laurate, methyl stearate, methyl myristate, ethyl laurate, ethyl palmitate, isopropyl stearate, isopropyl palmitate, butyl stearate, butyl palmitate, cetyl palmitate, and mixtures thereof, and the fatty acid (A2) is selected from the group consisting of palmitic acid, lauric acid, palmitic acid, lauric acid, stearic acid, myristic acid, decanoic acid, and mixtures thereof.

4. The phase change material component (A) is one of the following (a-i) to (a-vi), (a-i) The fatty acid ester is methyl palmitate, and the fatty acid is palmitic acid. (a-ii) The fatty acid ester is methyl palmitate, the fatty acid is palmitic acid, and the fatty alcohol is selected from the group consisting of tetradecanol, dodecanol, and mixtures thereof. (a-iii) The fatty acid ester is methyl laurate, and the fatty acid is lauric acid. (a-iv) The fatty acid ester is methyl stearate, and the fatty acid is palmitic acid. (a-v) The fatty acid ester is ethyl laurate, and the fatty acid is lauric acid, (a-vi) The composition according to claim 1 or 2, wherein the fatty acid ester is selected from one of the following: (a-vi) a mixture of 10 to 100 weight percent of ethyl palmitate and 0 to 90 weight percent of methyl palmitate, based on the total weight of the fatty acid ester, and the fatty acid is palmitic acid.

5. The composition according to claim 1 or 2, wherein the aliphatic isocyanate is selected from the group consisting of isophorone diisocyanate, hexamethylene diisocyanate, its dimer, its trimer, and mixtures thereof, and the aromatic isocyanate is selected from the group consisting of polymethylene polyphenyl isocyanate, methylenediphenyl diisocyanate, polycarbodiimide-modified methylenediphenyl diisocyanate, and mixtures thereof.

6. The isocyanate component is one of the following (b-i) to (b-iii), (b-i) A mixture of isophorone diisocyanate and polymethylene polyphenyl isocyanate, wherein the weight ratio of isophorone diisocyanate to polymethylene polyphenyl isocyanate is in the range of 3:7 to 7:

3. (b-ii) A mixture of hexamethylene diisocyanate trimer and polymethylene polyphenyl isocyanate, wherein the weight ratio of hexamethylene diisocyanate trimer to polymethylene polyphenyl isocyanate is in the range of 3:7 to 7:3, and (b-iii) The composition according to claim 1 or 2, comprising one of the mixtures of isophorone diisocyanate trimer and polymethylene polyphenyl isocyanate, wherein the weight ratio of isophorone diisocyanate trimer to polymethylene polyphenyl isocyanate is in the range of 3:7 to 7:

3.

7. The composition according to claim 1 or 2, wherein the microcapsules have a D90 in the range of 10 to 500 micrometers.

8. The composition according to claim 1 or 2, wherein the core and / or the shell each independently contain an inorganic filler present at a total concentration of 2 to 30 weight percent based on the weight of the phase change material component.

9. The composition according to claim 1 or 2, wherein the microcapsule has an average weight ratio of core to shell in the range of 2.0:1 to 10:

1.

10. The composition according to claim 1 or 2, wherein the microcapsules contain less than 0.1 weight percent of an emulsifier based on the total weight of the microcapsules.

11. A method for preparing the composition comprising microcapsules according to any one of claims 1 to 10, (I) To provide an oil phase mixture, wherein the oil phase mixture is (A) Phase change material component, (A1) Fatty acid esters, (A2) Based on the weight of the fatty acid ester, 1 to 6 weight percent of a fatty acid having 10 to 18 carbon atoms, and (A3) A phase change material component comprising 0 to 10 weight percent of fatty alcohol based on the weight of the fatty acid ester, (B) An isocyanate component comprising, based on the weight of the phase change material component, (B1) 1 to 20 weight percent of an aliphatic isocyanate having at least two isocyanate groups, and (B2) 1 to 20 weight percent of an aromatic isocyanate having at least two isocyanate groups, wherein the weight ratio of the aliphatic isocyanate to the aromatic isocyanate is in the range of 8.5:1.5 to 1.5:8.5, to provide an oil phase mixture. (II) To provide an aqueous amine solution containing an amine compound and water, wherein the amine compound comprises at least two amino functional groups selected from primary amino groups, secondary amino groups, or combinations thereof, and the amine compound is present in an amount that provides a molar ratio of the total primary and secondary amino groups in the amine compound to the total isocyanate groups in the isocyanate component, in the range of 0.3:1 to 1.5:

1. (III) Adding the oil phase mixture to the amine aqueous solution while stirring to form a reaction mixture, (IV) A method comprising maintaining the reaction mixture obtained from step (III) for a period of time until the microcapsules are obtained.

12. The method according to claim 11, wherein the amine compound is selected from the group consisting of diethylenetriamine, 1,3,5-cyclohexanetriamine, 1,2,3-propanetriamine, and mixtures thereof.

13. The method according to claim 11, wherein the oil phase mixture further comprises 2 to 30 weight percent of an inorganic filler based on the weight of the phase change material component.

14. The method according to claim 11, wherein the stirring in step (III) is performed at a speed of less than 1,500 revolutions per minute.

15. The method according to claim 11, wherein the method is carried out without the step of emulsifying the oil phase mixture using an emulsifier.

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