Compositions and methods for preparing microencapsulated phase change materials

Abstract

The present disclosure relates to compositions and methods for preparing microencapsulated phase change materials, the compositions including an oil phase component and an aqueous phase component, the oil phase component having, based on the total weight of the oil phase component, 40% to 99% by weight of a phase change material; - 0.5% to 30% by weight of an aliphatic isocyanate having at least two NCO-functional groups, - 0.5% to 30% by weight of an aromatic isocyanate having at least two NCO-functional groups, (2) the aqueous phase component comprises water in an amount at least three times the total weight of the oil phase ingredients; - a water-soluble amine compound having at least two NH-functional groups, the molar ratio of NH- ​​to NCO- being between 0.5:1 and 3:1; The method is a robust and efficient process that does not require organic solvents or surfactants.

Description

[Technical Field]

[0001] The present disclosure relates to compositions and methods for preparing microencapsulated phase change materials, which are robust and efficient processes that do not require solvents or surfactants. [Background technology]

[0002] Phase change materials (PCMs) have been widely studied and used in various types of applications. In building systems, many studies have demonstrated the ability of PCMs to reduce energy consumption. Solid-liquid PCMs are the most commonly used materials and have been extensively studied. Because solid-liquid PCMs melt after absorbing heat, they need to be encapsulated before being applied to building structures to prevent leakage. Generally, PCMs can be stabilized by impregnation, marco-encapsulation, and microencapsulation methods. The two main characteristics are their stabilization and heat transfer coefficient. A well-encapsulated PCM should have excellent stability and high heat transfer coefficient.

[0003] Impregnation is a method of imbibing a PCM using a porous matrix. However, there is still a risk of leakage during the melting and solidification cycles. Organic PCMs typically exhibit lower heat transfer coefficients. Therefore, the heat transfer coefficient of the impregnated material is highly dependent on the thermal conductivity of the matrix skeleton. Macroencapsulation (less than 1 mm) is also a simple and inexpensive method. However, heat transfer coefficients are typically low. Simulation work revealed that it takes 169.2 minutes to melt a 50 mm macrocapsule of wax. While the core may remain solid, the edges melt into a liquid form, thus preventing effective heat transfer. Microencapsulation (1-1000 μm) has proven to be an effective method for achieving high heat transfer coefficients due to its large surface area. Simulations showed that only 2.2 seconds were required for a capsule with a diameter of 500 μm.

[0004] Various encapsulation methods have been developed in recent decades to prepare PCM microcapsules. The three main methods are in situ polymerization, interfacial polymerization, and emulsion polymerization. During interfacial polymerization, an organic PCM is emulsified in an aqueous phase with an isocyanate by a surfactant. Sometimes, a solvent is added to the oil phase. A curing agent, such as an alcohol or amine, is slowly added to react with the NCO groups, resulting in a polyurea or polyurethane shell.

[0005] However, interfacial polymerization requires carefully controlled polymerization parameters, such as stirring speed and curing agent addition rate. Furthermore, phase change materials are typically immiscible with reactive aromatic isocyanates, which preferentially react quickly to form stable shells, often necessitating the use of solvents. Solvents may be added to aid in the dissolution of other isocyanates into the organic PCM. Solvents are not preferred for regulatory, environmental, and process efficiency reasons. Another important, yet less obvious, reason for removing solvents is wastewater treatment considerations if the system must be filtered to recover the microcapsule powder. Such solvent-free reactor systems allow both easy separation of the encapsulated material and easy reuse of the reactor effluent water. Aqueous surfactants or colloidal stabilizers may not be preferred in processes that recycle the reactor effluent, as their concentrations must be monitored and corrected to ensure the microcapsules maintain the desired particle size.

[0006] Therefore, there is still an urgent need for a unique method for preparing microencapsulated phase change materials that can overcome the above-mentioned drawbacks and meet all requirements regarding PCM microcapsules, environmental regulations and process efficiency.

[0007] After persistent research, the present inventors have surprisingly developed a unique composition for preparing microencapsulated phase change materials by using a specially designed formulation that can overcome the above-mentioned drawbacks in the production of PCM microcapsules. Summary of the Invention

[0008] The present disclosure provides a unique composition for preparing microencapsulated phase change materials and a method for preparing microencapsulated phase change materials using the composition.

[0009] In a first aspect of the present disclosure, the present disclosure provides a composition for preparing a microencapsulated phase change material, the composition comprising an oil phase component and an aqueous phase component; (1) The oil phase components are, based on the total weight of the oil phase components, 40% to 99% by weight of a phase change material; 0.5% to 30% by weight of an aliphatic isocyanate having at least two NCO-functional groups, 0.5% to 30% by weight of an aromatic isocyanate having at least two NCO-functional groups, Including, (2) The aqueous phase component is water in an amount at least three times the total weight of the oil phase ingredients; a water-soluble amine compound having at least two NH-functional groups, the molar ratio of NH- ​​to NCO- being between 0.5:1 and 3:1; The present invention provides a composition comprising:

[0010] In a second aspect of the present disclosure, the present disclosure provides a composition for preparing a microencapsulated phase change material, wherein the oil phase component further comprises 5 wt % to 25 wt % of an inorganic filler, based on the total weight of the oil phase component.

[0011] In a third aspect of the present disclosure, the present disclosure provides a method for preparing a microencapsulated phase change material, the method comprising: (1) blending a mixture of an aliphatic isocyanate having at least two NCO-functional groups and an aromatic isocyanate having at least two NCO-functional groups with a phase change material to form an oil phase component, wherein the oil phase component comprises, based on the total weight of the oil phase component: 40% to 99% by weight of a phase change material; 0.5% to 30% by weight of an aliphatic isocyanate having at least two NCO-functional groups, 0.5% to 30% by weight of an aromatic isocyanate having at least two NCO-functional groups, blending, (2) dissolving an amine compound having at least two NH-functional groups in water to form an aqueous phase component, the aqueous phase component comprising: water in an amount at least three times the total weight of the oil phase ingredients; a water-soluble amine compound having at least two NH-functional groups, the molar ratio of NH- ​​to NCO- being between 0.5:1 and 3:1; and (3) adding the oil phase component to the water phase component under agitation to form a microencapsulated phase change material.

[0012] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is an optical microscope photograph of a comparative example in the present disclosure. [Figure 2] 1 is an optical microscope photograph of an embodiment of the present invention in the present disclosure. [Figure 3] 1A shows an optical microscope photograph of Inventive Example 1 of the present disclosure at room temperature (a), a polarized light microscope photograph at room temperature (b), and a polarized light microscope photograph at 50° C. (c). [Figure 4] 1 is a DSC curve of 20 freeze-thaw cycles in the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0014] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Additionally, all publications, patent applications, patents, and other references mentioned herein are incorporated by reference.

[0015] As disclosed herein, "and / or" means "and, or alternatively" or "in addition, or alternatively." All ranges are inclusive of the endpoints unless otherwise indicated.

[0016] In certain embodiments of the present disclosure, the composition for preparing the microencapsulated phase change material comprises an oil phase component and a water phase component (ie, a two-component system). The oil phase component comprises 40 wt% to 99 wt%, 40 wt% to 90 wt%, 40 wt% to 80 wt%, 40 wt% to 70 wt%, 40 wt% to 60 wt%, 40 wt% to 50 wt%, 50 wt% to 99 wt%, 50 wt% to 90 wt%, 50 wt% to 80 wt%, 50 wt% to 70 wt%, 50 wt% to 60 wt%, 60 wt% to 99 wt%, 60 wt% to 90 wt%, 60 wt% to 80 wt%, 60 wt% to 70 wt%, 70 wt% to 99 wt%, 470 wt% to 90 wt%, 70 wt% to 80 wt%, 80 wt% to 99 wt%, 80 wt% to 90 wt%, or 90 wt% to 99 wt%, based on the total weight of the oil phase component, of a phase change material. The oil phase component comprises, based on the total weight of the oil phase component, 0.5 wt % to 30 wt %, 0.5 wt % to 25 wt %, 0.5 wt % to 20 wt %, 0.5 wt % to 15 wt %, 0.5 wt % to 10 wt %, 0.5 wt % to 5 wt %, 5 wt % to 30 wt %, 5 wt % to 25 wt %, 5 wt % to 20 wt %, 5 wt % to 15 wt %, 5 wt % to 10 wt %, 10 wt % to 30 wt %, 10 wt % to 25 wt %, 1.0 wt % to 20 wt %, 1.0 wt % to 15 wt %, 15 wt % to 30 wt %, 15 wt % to 25 wt %, 15 wt % to 20 wt %, 20 wt % to 30 wt %, 20 wt % to 25 wt %, or 25 wt % to 30 wt % of an aliphatic isocyanate having at least two NCO-functional groups. The oil phase component comprises, based on the total weight of the oil phase component, 0.5 wt % to 30 wt %, 0.5 wt % to 25 wt %, 0.5 wt % to 20 wt %, 0.5 wt % to 15 wt %, 0.5 wt % to 10 wt %, 0.5 wt % to 5 wt %, 5 wt % to 30 wt %, 5 wt % to 25 wt %, 5 wt % to 20 wt %, 5 wt % to 15 wt %, 5 wt % to 10 wt %, 10 wt % to 30 wt %, 10 wt % to 25 wt %, 1.0 wt % to 20 wt %, 1.0 wt % to 15 wt %, 15 wt % to 30 wt %, 15 wt % to 25 wt %, 15 wt % to 20 wt %, 20 wt % to 30 wt %, 20 wt % to 25 wt %, or 25 wt % to 30 wt % of an aromatic isocyanate having at least two NCO-functional groups.

[0017] In some embodiments of the present disclosure, the aqueous phase component comprises water in an amount at least 3 times, at least 4 times, or at least 5 times the total weight of the oil phase component, and the amine compound having at least two NH-functional groups is used in a molar ratio of NH- ​​to NCO- of 0.5:1 to 3:1, 0.5:1 to 2:1, 0.5:1 to 1:1, 0.5:1 to 0.7:1, 0.7:1 to 3:1, 0.7:1 to 2:1, 0.7:1 to 1:1, 1:1 to 3:1, 1:1 to 2:1, or 2:1 to 3:1.

[0018] In some embodiments of the present disclosure, the phase change material may include an organic PCM or a eutectic PCM. Examples of phase change materials include paraffin hydrocarbons (e.g., C14 to C45 paraffin hydrocarbons, e.g., paraffin wax, C14, C18, C22 to C45 hydrocarbons, e.g., tetradecane, pentadecane, hexadecane, heptadecane, octadecane), carboxylic acid esters (e.g., fatty acid esters, methyl laurate, ethyl laurate, methyl stearate, ethyl stearate, methyl behenate, and ethyl behenate), carboxylic acids (e.g., fatty acids, capric acid, lauric acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, octadecanoic acid), polyalcohols (e.g., polyethylene glycol (PEG)), and the like.

[0019] In certain embodiments of the present disclosure, the aliphatic isocyanates having at least two NCO-functional groups include aliphatic diisocyanates and their dimers and trimers, C2-C8 alkylene diisocyanates, such as tetramethylene diisocyanate and hexamethylene diisocyanate (HDI), 1,12-dodecane diisocyanate, 2,2,4-trimethyl-hexamethylene diisocyanate, 2,4,4-trimethyl-hexamethylene diisocyanate, 2-methyl-1,5-pentamethylene diisocyanate; alicyclic diisocyanates and their dimers and trimers, such as isophorone diisocyanate (IPDI) and dicyclohexyl methane diisocyanate. diisocyanate (HMDI), 1,4-cyclohexane diisocyanate, and 1,3-bis-(isocyanatomethyl)cyclohexane; aromatic diisocyanates and their dimers and trimers, such as toluene diisocyanate (TDI) and diphenyl methane diisocyanate (MDI). Preferably, the aliphatic isocyanate is a hexamethylene diisocyanate homopolymer, a hexamethylene diisocyanate adduct, an isophorone diisocyanate homopolymer, an isophorone diisocyanate adduct, or a mixture thereof. Most preferably, the aliphatic isocyanate having at least two NCO-functional groups is selected from the group consisting of methylene-bis(cyclohexylisocyanate) (HMDI), hexamethylene-diisocyanate (HDI), tetramethylene-diisocyanate, cyclohexane-diisocyanate, hexahydrotoluene diisocyanate, isophorone diisocyanate (IPDI), and any mixture thereof.

[0020] In one embodiment of the present disclosure, the aromatic isocyanate compound is a C6-C6 aromatic isocyanate having at least two isocyanate (NCO-) groups. 15 Aromatic isocyanate compounds. C6-C15 The aromatic isocyanate compound may be selected from the group consisting of diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), naphthalene diisocyanate (NDI), phenylene diisocyanate, any isomer thereof, and any combination thereof. MDI isomers include 4,4'-MDI, 2,4'-MDI, 2,2'-MDI, etc. TDI isomers include 2,3-TDI, 2,4-TDI, 2,5-TDI, 2,6-TDI, 3,4-TDI, 3,5-TDI, etc. NDI isomers include 1,5-NDI, 1,2-NDI, 1,3-NDI, 1,4-NDI, 1,6-NDI, 1,7-NDI, 1,8-NDI, 2,3-NDI, 2,6-NDI, 2,7-NDI, etc. Isomers of phenylene diisocyanate include 1,2-phenylene diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, etc. The aromatic isocyanate compound may contain any one or more of the isomers shown above. According to one embodiment of the present invention, the aromatic isocyanate compound is MDI, for example, a mixture of 4,4'-MDI and 2,4'-MDI, specifically, a mixture of 50 to 99% by weight of 4,4'-MDI and 1 to 50% by weight of 2,4'-MDI, or a mixture of 98% by weight of 4,4'-MDI and 2% by weight of 2,4'-MDI. Preferably, the aromatic isocyanate compound is selected from the group consisting of polymethylene polyphenylisocyanate, diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), naphthalene diisocyanate (NDI), phenylene diisocyanate, and any combination thereof.

[0021] In some embodiments of the present disclosure, the amine compound is water-soluble and includes an aromatic polyamine having at least two NH-functional groups, with the primary amino group directly bonded to a carbon atom of the aromatic ring. Examples of such aromatic polyamines include 2,4- and / or 2,6-toluene diamine (TDA), 4,4'-, 2,4'-, and 2,2'-diphenylmethane diamine (MDA), or a mixture of any two or more thereof. Examples of water-soluble amine compounds having at least two NH-functional groups include alicyclic polyamines such as hydrogenated MDA, 1-methyl-2,4-diaminocyclohexane, and 1-methyl-2,6-diaminocyclohexane. The amine compound is water-soluble and has at least two NH-functional groups, and examples thereof include aliphatic polyamines such as tetramethylene-1,4-diamine, hexamethylene-1,6-diamine, trimethylhexanediamine, tetramethylhexanediamine, isophoronediamine, 1,3- and / or 1,4-bis(aminomethyl)cyclohexane, and 2,4- or 2,6-diamine-1-methylecyclohexane. Preferably, the amine compound is selected from the group consisting of diethylenetriamine (DETA), triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, ethylenediamine (EDA), propylenediamine and triethylenediamine, 2,4- and / or 2,6-toluenediamine (TDA), 4,4'-, 2,4'- and 2,2'-diphenylmethanediamine (MDA), 1-methyl-2,4-diaminocyclohexane, 1-methyl-2,6-diaminocyclohexane, tetramethylene-1,4-diamine, hexamethylene-1,6-diamine, trimethylhexanediamine, tetramethylhexanediamine, isophoronediamine, 1,3- and / or 1,4-bis(aminomethyl)cyclohexane and 2,4- or 2,6-diamine-1-methylecyclohexane, and any combination thereof.

[0022] In some embodiments of the present disclosure, the oil phase component further comprises 5 wt. % to 25 wt. %, 5 wt. % to 20 wt. %, 5 wt. % to 15 wt. %, 5 wt. % to 10 wt. %, 10 wt. % to 25 wt. %, 10 wt. % to 20 wt. %, 10 wt. % to 15 wt. %, 15 wt. % to 25 wt. %, 15 wt. % to 20 wt. %, or 20 wt. % to 25 wt. % of an inorganic filler, based on the total weight of the oil phase component. Exemplary inorganic fillers include, but are not limited to, natural calcium carbonates 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, metal or alkaline earth oxides or hydroxides, magnesium hydroxide, iron oxide, zinc oxide, glass, or carbon fibers or powders, or powders or mixtures of these compounds. Preferably, the inorganic filler is selected from the group consisting of CaCO3, talc, mica, SiO2, TiO2, kaolin, coal gangue powder, sepiolite powder, attapulgite powder, montmorillonite, and any combination thereof.

[0023] In some embodiments of the present disclosure, there is no need to add a surfactant to the composition, so there is no emulsification process. An amine compound as a curing agent is first added and dissolved in the water phase. Then, the oil phase components are added to the water phase components. During the addition, the isocyanate in the oil phase components reacts rapidly with the curing agent to form a thin film, maintaining the shape of the microcapsules. Oil phase dispersion and shell formation occur almost simultaneously. This process is straightforward and robust. The composition for preparing microencapsulated phase change materials is substantially free of any surfactants (e.g., sulfate surfactants, sulfonate surfactants, nonionic surfactants, etc.), stabilizers, organic solvents, and emulsifiers (e.g., sodium salt of styrene-maleic anhydride copolymer, sodium dodecylbenzenesulfonate, alkylphenol polyoxyethylene ether (OP-10), etc.). Generally, surfactants include anionic surfactants, cationic surfactants, amphoteric surfactants or nonionic surfactants, such as sulfate salts of ethoxylated phenols, such as poly(oxy-1,2-ethanediyl) α-sulfo-ω(nonylphenoxy) salts; alkali metal fatty acid salts, such as alkali metal oleates and stearates; 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 sulfate, or triethanolamine lauryl sulfate; alkali metal C 12 ~C 16 Alkylbenzene sulfonates, such as branched and linear sodium dodecylbenzene sulfonate; amines such as triethanolamine dodecylbenzene sulfonate; 12 ~C 16 Alkylbenzene sulfonates; fluorinated C4-C 16 Alkyl esters and alkali metals C4-C 16 These include anionic and nonionic fluorocarbon emulsifiers such as perfluoroalkylsulfonates; and organosilicon emulsifiers such as modified polydimethylsiloxanes.

[0024] In some embodiments of the present invention, the microcapsule structure comprises one or a combination of a core-shell structure, a single-shell structure, a multi-shell structure, a single-cavity-single-core structure, a single-cavity-multi-core structure, a multi-cavity-multi-core structure, a porous structure, a skeletal structure, and a three-dimensional network structure.

[0025] The present disclosure provides an exemplary composition for preparing a microencapsulated phase change material, the composition comprising an oil phase component and an aqueous phase component, (1) The oil phase components are, based on the total weight of the oil phase components, 40% to 99% by weight of paraffin wax; 0.5% to 30% by weight of isophorone diisocyanate (IPDI) and / or dicyclohexylmethane-4,4'-diisocyanate (HMDI), 0.5% to 30% by weight of polymethylene polyphenyl isocyanate; 5% to 25% by weight of CaCO3 and / or talc, Including, (2) The aqueous phase component is water in an amount at least three times the total weight of the oil phase ingredients; diethylenetriamine (DETA) in which the molar ratio of NH— to NCO— is from 0.5:1 to 3:1; A composition comprising:

[0026] In an embodiment of the present disclosure, there is provided a method for preparing a microencapsulated phase change material, comprising: (1) blending a mixture of an aliphatic isocyanate having at least two NCO-functional groups and an aromatic isocyanate having at least two NCO-functional groups with a phase change material to form an oil phase component; (2) dissolving an amine compound having at least two NH-functional groups in water to form an aqueous phase component; (3) adding, under agitation, the oil phase component to the water phase component to form a dispersion of microencapsulated phase change material.

[0027] In a further embodiment of the present disclosure, step (1) further comprises blending the mixture of the aliphatic isocyanate having at least two NCO-functional groups and the aromatic isocyanate having at least two NCO-functional groups, and the phase change material with an inorganic filler. In an alternative embodiment of the present disclosure, step (3) further comprises adding an inorganic filler to the water phase component separately from or together with the oil phase component.

[0028] In a further embodiment of the present disclosure, the method for preparing a microencapsulated phase change material further comprises, after step (3), step (4) of filtering the dispersion to provide a microencapsulated phase change material powder, which step (4) also produces a filtrate.

[0029] In a further embodiment of the present disclosure, the method for preparing a microencapsulated phase change material further comprises, after step (4), recycling the filtrate to step (3).

[0030] In the present disclosure, an exemplary method for preparing a microencapsulated phase change material includes: 1) blending a mixture of an aliphatic isocyanate having at least two NCO-functional groups and an aromatic isocyanate having at least two NCO-functional groups with paraffin wax and an inorganic filler (e.g., an anti-caking agent, e.g., CaCO3 and / or talc) to form an oil phase; 2) dissolving an amine compound having at least two NH-functional groups (as a curing agent) in water to provide an aqueous phase; 3) Pour the oil phase into the water phase while stirring, alternatively, do not use surfactants, colloidal stabilizers, or internal stabilizers (such as DMPA); 4) curing the mixture obtained in 3) for several hours (e.g., 8 hours) to provide a microcapsule dispersion; 5) filtering the dispersion to form a microcapsule powder and a filtrate; 6) recycling the filtrate to 3) for polymerization.

[0031] The present disclosure provides a feasible microencapsulation method for obtaining organic PCM microcapsules, which has the following advantages: a) robust and efficient processes; b) does not use solvents or surfactants; c) the filtrate is reusable, and d) The shell thickness can be controlled to balance cost and leak protection. The present specification includes the following aspects. Section 1: A composition for preparing a microencapsulated phase change material, the composition comprising an oil phase component and an aqueous phase component; (1) The oil phase component, based on the total weight of the oil phase component, 40% to 99% by weight of a phase change material; 0.5% to 30% by weight of an aliphatic isocyanate having at least two NCO-functional groups, 0.5% to 30% by weight of an aromatic isocyanate having at least two NCO-functional groups, Including, (2) The aqueous phase component is water in an amount at least three times the total weight of the oil phase components; a water-soluble amine compound having at least two NH-functional groups, the molar ratio of NH- ​​to NCO- being 0.5:1 to 3:1; A composition comprising: Section 2: The oil phase component, based on the total weight of the oil phase component, 50% to 90% by weight of a phase change material; 5% to 25% by weight of an aliphatic isocyanate having at least two NCO-functional groups, 5% to 25% by weight of aromatic isocyanates having at least two NCO-functional groups, Item 1. The composition according to item 1, comprising: Section 3: The aqueous phase component water in an amount at least four times the total weight of the oil phase components; Item 1. The composition according to item 1, comprising: an amine compound having at least two NH-functional groups, wherein the molar ratio of NH- ​​to NCO- is 0.7:1 to 2:1. Section 4: the aliphatic isocyanate is selected from the group consisting of methylene-bis(cyclohexylisocyanate) (HMDI), hexamethylene-diisocyanate (HDI), tetramethylene-diisocyanate, cyclohexane-diisocyanate, hexahydrotoluene diisocyanate, isophorone diisocyanate (IPDI), and any mixture thereof; the aromatic isocyanate compound is selected from the group consisting of polymethylene polyphenylisocyanate, diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), naphthalene diisocyanate (NDI), phenylene diisocyanate, and any combination thereof; and / or The composition according to any one of items 1 to 3, wherein the amine compound is selected from the group consisting of diethylenetriamine (DETA), triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, ethylenediamine (EDA), propylenediamine and triethylenediamine, 2,4- and / or 2,6-toluenediamine (TDA), 4,4'-, 2,4'- and 2,2'-diphenylmethanediamine (MDA), 1-methyl-2,4-diaminocyclohexane, 1-methyl-2,6-diaminocyclohexane, tetramethylene-1,4-diamine, hexamethylene-1,6-diamine, trimethylhexanediamine, tetramethylhexanediamine, isophoronediamine, 1,3- and / or 1,4-bis(aminomethyl)cyclohexane and 2,4- or 2,6-diamine-1-methylecyclohexane, and any combination thereof. Section 5: Item 4. The composition according to any one of Items 1 to 3, wherein the oil phase component further comprises 5 wt % to 25 wt % of an inorganic filler based on the total weight of the oil phase component, and the inorganic filler is selected from the group consisting of CaCO, talc, mica, SiO, TiO, kaolin, coal gangue powder, sepiolite powder, attapulgite powder, montmorillonite, and any combination thereof. Item 6: Item 4. The composition according to any one of Items 1 to 3, wherein the composition does not contain a surfactant, a stabilizer, an organic solvent, or an emulsifier. Section 7: 1. A method for preparing a microencapsulated phase change material, comprising: (1) blending a mixture of an aliphatic isocyanate having at least two NCO-functional groups and an aromatic isocyanate having at least two NCO-functional groups with a phase change material to form an oil phase component, the oil phase component comprising, based on the total weight of the oil phase component: 40% to 99% by weight of a phase change material; 0.5% to 30% by weight of an aliphatic isocyanate having at least two NCO-functional groups, 0.5% to 30% by weight of an aromatic isocyanate having at least two NCO-functional groups, blending, (2) dissolving an amine compound having at least two NH-functional groups in water to form an aqueous phase component, the aqueous phase component comprising: water in an amount at least three times the total weight of the oil phase components; an amine compound having at least two NH-functional groups, the molar ratio of NH- ​​to NCO- being 0.5:1 to 3:1; and (3) adding, under agitation, the oil phase component to the water phase component to form a dispersion of microencapsulated phase change material; A method comprising: Section 8: The oil phase component, based on the total weight of the oil phase component, 50% to 90% by weight of a phase change material; 5% to 25% by weight of an aliphatic isocyanate having at least two NCO-functional groups, 5% to 25% by weight of aromatic isocyanates having at least two NCO-functional groups, Item 7. The method according to Item 7, comprising: Section 9: The aqueous phase component water in an amount at least four times the total weight of the oil phase components; an amine compound having at least two NH-functional groups, the molar ratio of NH- ​​to NCO- being 0.7:1 to 2:1; Item 7. The method according to Item 7, comprising: Section 10: the aliphatic isocyanate is selected from the group consisting of methylenebis(cyclohexylisocyanate) (HMDI), hexamethylenediisocyanate (HDI), tetramethylenediisocyanate, cyclohexanediisocyanate, hexahydrotoluenediisocyanate, isophoronediisocyanate (IPDI), and any mixture thereof; the aromatic isocyanate compound is selected from the group consisting of polymethylene polyphenylisocyanate, diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), naphthalene diisocyanate (NDI), phenylene diisocyanate, and any combination thereof; and / or Item 10. The method according to any one of Items 7 to 9, wherein the amine compound is selected from the group consisting of diethylenetriamine (DETA), triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, ethylenediamine (EDA), propylenediamine and triethylenediamine, 2,4- and / or 2,6-toluenediamine (TDA), 4,4'-, 2,4'- and 2,2'-diphenylmethanediamine (MDA), 1-methyl-2,4-diaminocyclohexane, 1-methyl-2,6-diaminocyclohexane, tetramethylene-1,4-diamine, hexamethylene-1,6-diamine, trimethylhexanediamine, tetramethylhexanediamine, isophoronediamine, 1,3- and / or 1,4-bis(aminomethyl)cyclohexane and 2,4- or 2,6-diamine-1-methylecyclohexane, and any combination thereof. Section 11: Item 10. The method according to any one of items 7 to 9, wherein step (1) further comprises blending the mixture, the phase change material, with an inorganic filler such that the oil phase component further comprises 5 wt% to 25 wt% of the inorganic filler based on the total weight of the oil phase component. Section 12: Item 10. The method according to any one of Items 7 to 9, wherein step (3) further comprises adding an inorganic filler in an amount of 5 wt% to 25 wt% based on the total weight of the oil phase components, and the inorganic filler is selected from the group consisting of CaCO, talc, mica, SiO, TiO, kaolin, coal gangue powder, sepiolite powder, attapulgite powder, montmorillonite, and any combination thereof. Section 13: Item 10. The method according to any one of Items 7 to 9, wherein the method does not contain surfactants, stabilizers, organic solvents, or emulsifiers. Section 14: Item 10. The method of any one of items 7 to 9, wherein the method further comprises, after step (3), step (4) of filtering the dispersion to provide a microencapsulated phase-change material powder, and step (4) also produces a filtrate. Section 15: Item 15. The method of item 14, further comprising, after step (4), recycling the filtrate to step (3). [Example]

[0032] Some embodiments of the present invention are now described in the following examples, in which all parts and percentages are by weight unless otherwise specified.

[0033] Information on the raw materials used in the examples is listed in Table 1 below.

[0034] [Table 1]

[0035] Examples 1 to 5 of the present invention and Comparative Examples 1 to 4 In the following Inventive Examples (IE) 1 to 5 and Comparative Examples (CE) 1 to 4, microencapsulated phase change materials were prepared according to the compositions and processes set forth in Table 2.

[0036] A. Oil Phase Preparation For IE1-4 and CE1-4, the wax was heated to about 50° C. to obtain a hot liquid wax. The aliphatic and aromatic isocyanate mixture and filler (if present) were added to the hot liquid wax according to the composition set forth in Table 2.

[0037] In IE5, the wax was heated to about 50° C. to obtain a hot liquid wax. An aliphatic and aromatic isocyanate mixture was added to the hot liquid wax according to the composition set forth in Table 2.

[0038] B. Preparation of the aqueous phase For IE1-5 and CE1-4, the water was heated to about 50°C and then the curing agent was added according to the composition listed in Table 2.

[0039] C. Mixing of oil and water phases In IE1-5 and CE1-4, the hot oil phase was poured into the water phase while stirring at about 500 rpm.

[0040] D. Curing by interfacial polymerization For IE1-4 and CE1-4, aliphatic and aromatic isocyanate mixtures were cured with a curing agent via interfacial polymerization at about 50° C. for 6 hours to obtain dispersions of microencapsulated phase change materials.

[0041] In IE5, a mixture of aliphatic and aromatic isocyanates was cured with a curing agent via interfacial polymerization at approximately 50°C for 6 hours to obtain a dispersion of microencapsulated phase-change material. After 6 hours of interfacial polymerization, 10 g of 800 mesh mica powder was added.

[0042] E. Filtration of the dispersion The dispersions of the microencapsulated phase-change materials (IE1 to 4) or the microcapsule aggregates (CE3 to 4) were filtered to obtain microcapsule powders.

[0043] [Table 2]

[0044] Testing and Evaluation The morphology of the microencapsulated phase-change materials obtained in IE1-5 and CE1-4 was examined using an optical microscope. In IE1-5 and CE1-4, a droplet of the cured PCM dispersion was taken and placed on a glass slide. The droplet was then dried at room temperature and placed under an optical microscope for observation.

[0045] Figure 1 shows optical microscope photographs of Comparative Examples CE1-4. Figure 2 shows optical microscope photographs of Examples IE1-5 of the present invention. Figure 3(a) shows an optical microscope photograph of IE1 at room temperature. Figure 3(b) shows a polarized light microscope photograph of IE1 at room temperature. Figure 3(c) shows a polarized light microscope photograph of IE1 at 50°C. Figure 4 shows DSC curves for 20 freeze-thaw cycles.

[0046] Comparing CE1 in Figure 1 with IE1 in Figure 2 reveals that microcapsules cannot be obtained if the aqueous phase does not contain an amine curing agent. The isocyanate mixture in CE1 reacts with water, but the reaction rate is not fast enough to form a solid shell to protect the microcapsules, even when the temperature is raised to approximately 50°C. The amine in the aqueous phase is an essential component for immediately reacting with the isocyanate to form a solid shell when the oil phase is dispersed in the aqueous phase.

[0047] Microcapsules can also be formed when the oil phase does not contain a filler (CE2 in Figure 1). However, the dispersion becomes thick after the reaction, which means that the polymer from the reaction between the isocyanate and the amine or water in the aqueous phase thickens the dispersion. Furthermore, the resulting microcapsules cannot be filtered due to their weak shell. The added inorganic filler not only helps the polyurea polymer settle on the microcapsule surface, but also plays an important role in preventing caking of the filtered microcapsules. Different types of inorganic fillers can be used, such as CaCO3, mica powder, talcum powder, etc.

[0048] Aliphatic isocyanates such as IPDI, HMDI, and HDI are miscible with wax liquids, but aromatic isocyanates typically have relatively low solubility in wax liquids. Therefore, a mixture of aliphatic and aromatic isocyanates was used to balance solubility, reaction rate, and crosslink density. Microcapsules were obtained using these compositions, as shown in Figure 2. The microcapsule sizes ranged from 1 to 200 mm.

[0049] IPDI was used to prepare microcapsules. The product morphology is shown in Figure 1, CE3. Only microcapsule aggregates were obtained. This is thought to be due to the hydrophilic IPDI-DETA prepolymer that formed diffusing into the aqueous phase and the aggregation of the microdroplets. PAPI27 was also used in the product form shown in Figure 1, CE4. Due to its low solubility in the wax liquid and the rapid reaction rate, aggregation of the microcapsules also occurred.

[0050] IE1 to IE3 in FIG. 2 indicate the following. -Mixtures of aliphatic and aromatic isocyanates can provide a good balance between solubility and reaction rate to produce microcapsules rather than agglomeration of microcapsules (CE3-4 in Figure 1 vs. IE1-3 in Figure 2). - An amine curing agent in the water phase is an essential component (CE1 in Figure 1 versus IE1-3 in Figure 2). With the aid and reinforcement of inorganic fillers, the microcapsules can be filtered to form a powder or slurry (CE2 in Figure 1 vs. IE1-3 in Figure 2). - Different types of fillers can be used (IE2 in Figure 1 vs. IE1 in Figure 2). -PCMs with different melting points can be used (IE3 in Figure 1 vs. IE1 and IE2 in Figure 2).

[0051] As shown in IE4 of Figure 2, the filtrate can be recycled and used in the aqueous phase so that the method of the present invention for preparing microencapsulated PCM is environmentally friendly. As shown in IE5, a filler anti-cake aid may be added after the reaction, which may provide more latitude in the manufacturing process.

[0052] The resulting microcapsules can achieve good solidification-melting stability, as shown in Figure 3. Figure 3(a) shows an optical microscope image of IE1 in Figure 2 at room temperature. When the wax is in a crystalline phase, it exhibits bright crystalline domains under a polarizing microscope, as shown in Figure 3(b). When the wax in the microcapsules melts after heating, the bright crystalline domains disappear, as shown in Figure 3(c). The stability is also demonstrated by DSC testing. As shown in IE3 in Figure 2, after 20 cycles of heating and cooling the microcapsules, no latent heat reduction occurs, as shown in Figure 4.

Claims

1. A composition for preparing a microencapsulated phase change material, the composition comprising an oil phase component and an aqueous phase component; (1) The oil phase component contains, based on the total weight of the oil phase component, 40% to 99% by weight of a phase change material; 0.5% to 30% by weight of an aliphatic isocyanate having at least two NCO-functional groups, 0.5% to 30% by weight of an aromatic isocyanate having at least two NCO-functional groups, Including, (2) The aqueous phase component is Water in an amount at least three times the total weight of the oil phase components; a water-soluble amine compound having at least two NH-functional groups, the molar ratio of NH- ​​to NCO- being from 0.5:1 to 3:1; Including, A composition wherein the oil phase component further comprises 5% to 25% by weight of an inorganic filler, based on the total weight of the oil phase component.

2. The oil phase component, based on the total weight of the oil phase component, 50% to 90% by weight of a phase change material; 5% to 25% by weight of an aliphatic isocyanate having at least two NCO-functional groups, 5% to 25% by weight of an aromatic isocyanate having at least two NCO-functional groups, The composition of claim 1 comprising:

3. The aqueous phase component Water in an amount at least 4 times the total weight of the oil phase components; a water-soluble amine compound having at least two NH-functional groups, the molar ratio of NH- ​​to NCO- being from 0.7:1 to 2:1; The composition of claim 1 comprising:

4. the aliphatic isocyanate is selected from the group consisting of methylene-bis(cyclohexylisocyanate) (HMDI), hexamethylene-diisocyanate (HDI), tetramethylene-diisocyanate, cyclohexane-diisocyanate, hexahydrotoluene diisocyanate, isophorone diisocyanate (IPDI), and any mixture thereof; the aromatic isocyanate compound is selected from the group consisting of polymethylene polyphenylisocyanate, diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), naphthalene diisocyanate (NDI), phenylene diisocyanate, and any combination thereof; and / or 4. The composition of claim 1, wherein the water-soluble amine compound is selected from the group consisting of diethylenetriamine (DETA), triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, ethylenediamine (EDA), propylenediamine and triethylenediamine, 2,4- and / or 2,6-toluenediamine (TDA), 4,4'-, 2,4'- and 2,2'-diphenylmethanediamine (MDA), 1-methyl-2,4-diaminocyclohexane, 1-methyl-2,6-diaminocyclohexane, tetramethylene-1,4-diamine, hexamethylene-1,6-diamine, trimethylhexanediamine, tetramethylhexanediamine, isophoronediamine, 1,3- and / or 1,4-bis(aminomethyl)cyclohexane and 2,4- or 2,6-diamine-1-methylecyclohexane, and any combination thereof.

5. The inorganic filler is CaCO ３ , talc, mica, SiO ２ , TiO ２ 4. The composition of claim 1, wherein the inorganic filler is selected from the group consisting of kaolin, coal gangue powder, sepiolite powder, attapulgite powder, montmorillonite, and any combination thereof.

6. The composition according to any one of claims 1 to 3, wherein the composition is free of surfactants, stabilizers, organic solvents and emulsifiers.

7. 1. A method for preparing a microencapsulated phase change material, comprising: (1) blending a mixture of an aliphatic isocyanate having at least two NCO-functional groups and an aromatic isocyanate having at least two NCO-functional groups with a phase change material to form an oil phase component, wherein the oil phase component comprises, based on the total weight of the oil phase component: 40% to 99% by weight of a phase change material; 0.5% to 30% by weight of an aliphatic isocyanate having at least two NCO-functional groups, 0.5% to 30% by weight of an aromatic isocyanate having at least two NCO-functional groups, Step (1), (2) dissolving a water-soluble amine compound having at least two NH-functional groups in water to form an aqueous phase component, the aqueous phase component comprising: Water in an amount at least three times the total weight of the oil phase components; a water-soluble amine compound having at least two NH-functional groups, the molar ratio of NH- ​​to NCO- being from 0.5:1 to 3:1; Step (2) including: (3) adding the oil phase component to the water phase component under stirring to form a dispersion of microencapsulated phase change material; Including, The method, wherein step (1) further comprises blending an inorganic filler such that the oil phase component further comprises 5% to 25% by weight of an inorganic filler based on the total weight of the oil phase component, or wherein step (3) further comprises adding 5% to 25% by weight of an inorganic filler based on the total weight of the oil phase component.

8. The oil phase component, based on the total weight of the oil phase component, 50% to 90% by weight of a phase change material; 5% to 25% by weight of an aliphatic isocyanate having at least two NCO-functional groups, 5% to 25% by weight of an aromatic isocyanate having at least two NCO-functional groups, The method of claim 7, comprising:

9. The aqueous phase component Water in an amount at least 4 times the total weight of the oil phase components; a water-soluble amine compound having at least two NH-functional groups, the molar ratio of NH- ​​to NCO- being from 0.7:1 to 2:1; The method of claim 7, comprising:

10. the aliphatic isocyanate is selected from the group consisting of methylenebis(cyclohexylisocyanate) (HMDI), hexamethylenediisocyanate (HDI), tetramethylenediisocyanate, cyclohexanediisocyanate, hexahydrotoluenediisocyanate, isophoronediisocyanate (IPDI), and any mixture thereof; the aromatic isocyanate compound is selected from the group consisting of polymethylene polyphenylisocyanate, diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), naphthalene diisocyanate (NDI), phenylene diisocyanate, and any combination thereof; and / or 10. The method of any one of claims 7 to 9, wherein the water-soluble amine compound is selected from the group consisting of diethylenetriamine (DETA), triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, ethylenediamine (EDA), propylenediamine and triethylenediamine, 2,4- and / or 2,6-toluenediamine (TDA), 4,4'-, 2,4'- and 2,2'-diphenylmethanediamine (MDA), 1-methyl-2,4-diaminocyclohexane, 1-methyl-2,6-diaminocyclohexane, tetramethylene-1,4-diamine, hexamethylene-1,6-diamine, trimethylhexanediamine, tetramethylhexanediamine, isophoronediamine, 1,3- and / or 1,4-bis(aminomethyl)cyclohexane and 2,4- or 2,6-diamine-1-methylecyclohexane, and any combination thereof.

11. The inorganic filler is CaCO ３ , talc, mica, SiO ２ , TiO ２ 10. The method of any one of claims 7 to 9, wherein the inorganic fine particles are selected from the group consisting of kaolin, coal gangue powder, sepiolite powder, attapulgite powder, montmorillonite, and any combination thereof.

12. The method according to any one of claims 7 to 9, wherein the method is free of surfactants, stabilizers, organic solvents and emulsifiers.

13. 10. The method of claim 7, wherein the method further comprises, after step (3), step (4) of filtering the dispersion to provide a microencapsulated phase change material powder, wherein step (4) also produces a filtrate.

14. 14. The method of claim 13, wherein the method further comprises, after step (4), recycling the filtrate to step (3).

Images