CN111621265A - Phase change microcapsule based on inorganic shell layer and manufacturing method and application thereof - Google Patents

Abstract

The present invention provides a phase-change microcapsule based on an inorganic shell layer and a manufacturing method and application thereof. The invention stabilizes the emulsion by Janus particles and utilizes the sol-gel reaction at the water-oil interface to obtain phase-change microcapsules based on inorganic shell layers covered by composite wall materials containing Janus particles. The phase-change microcapsule based on the inorganic shell layer of the present invention has a controllable phase-change temperature, high enthalpy retention rate, and effectively reduces the degree of supercooling of the solid-liquid phase change material. The phase change microcapsule based on the inorganic shell layer of the present invention has a low breakage rate during use, no leakage of the phase change material, no generation of volatile gas, excellent use stability, safety and environmental protection. In addition, the phase-change microcapsules covered by the composite wall material of the present invention can be prepared in a green manner, and no toxic and volatile substances are produced during the preparation process. The phase-change microcapsule of the invention has simple process and short production period, and has the prospect of industrial mass production.

Description

Phase-change microcapsules based on inorganic shell layers and their manufacturing methods and applications

technical field

The invention relates to a phase change microcapsule based on an inorganic shell layer, a manufacturing method and application thereof, and in particular to an inorganic shell layer-based microcapsule with controllable phase transition temperature, high heat storage density and high enthalpy retention rate. Phase-change microcapsules and their manufacturing methods and applications.

Background technique

Microencapsulation of phase change materials is considered to be one of the most important technical means to solve major defects such as leakage and deformation of solid-liquid phase change materials. Due to the small particles, large specific surface area, large latent heat of phase change and collisional heat exchange between particles, phase change microcapsules are widely used in solar energy industry, industrial waste heat and waste heat recovery, air conditioning energy saving, building heating and other fields. The preparation of phase change microcapsules generally first obtains an emulsion with homogeneous phase change material droplets (particles) as the dispersed phase; and then uses chemical or physical methods to obtain a stable shell layer to coat the phase change material particles; During the phase change process of the phase change microcapsules, the phase change core material undergoes a solid-liquid transition, while the shell layer remains solid, thus solving the leakage and deformation of the phase change material. Therefore, the key points of this microcapsule technology lie in the emulsification of phase change materials and the preparation of stable shell layers.

In recent years, because Janus particles have both the ability of traditional surfactants to weaken the interfacial energy of water-oil and the mechanical barrier of solid nanoparticles at the water-oil interface (Pickering effect), their emulsifying ability has been widely concerned, and the obtained Janus particles are stable The emulsion has excellent performance. The Janus particles with different morphologies and compositions are mentioned in Patent Documents 1 to 4, and the prepared Janus particles can well stabilize the emulsion.

As the shell material (wall material) of the phase change microcapsules, the organic-inorganic composite wall material is considered to have higher practical value. It has the characteristics of certain flame retardancy and constant phase transition temperature. Patent Document 5 designs a kaolin/polyurea composite wall material, Patent Document 6 provides a zirconium carbide/melamine-formaldehyde resin composite wall material, and Patent Document 7 mentions a series of nanoparticle/polymer composite wall materials.

However, the phase change microcapsules covered by the composite wall material disclosed at present still have certain defects, which are mainly concentrated in that the encapsulation effect and the enthalpy retention rate cannot be well balanced.

prior art literature

Patent Literature

Patent Document 1: CN 105777998 A

Patent Document 2: CN 104209505 A

Patent Document 3: CN 101885813 A

Patent Document 4: CN 103204508 A

Patent Document 5: CN 110215885 A

Patent Document 6: CN 110343511 A

Patent Document 7: CN 106367031 A

SUMMARY OF THE INVENTION

Invention to solve problem

One of the objectives of the present invention is to provide phase change microcapsules based on inorganic shell layers, which have controllable phase transition temperature, high heat storage density and high enthalpy retention rate, and can effectively take into account the encapsulation effect and enthalpy retention rate.

In addition, another object of the present invention is to provide a method for manufacturing the phase-change microcapsules based on the inorganic shell layer, which can freely control the phase-change temperature of the phase-change material and efficiently control the phase-change material and Janus particles. In addition, the process is simple, the production cycle is short, and it has the prospect of industrial mass production.

In addition, another object of the present invention is to provide the inorganic shell-based phase change microcapsules for textile materials, building energy-saving materials, materials in the fields of thermal management of electronic components and waste heat recovery, space thermal protection materials, weapons The application of temperature control materials for equipment warehouse walls or wearable equipment materials in the military field.

solution to the problem

In order to solve the above-mentioned problems, the inventors of the present invention have conducted intensive research, starting from the designability of Janus particles, and found that by using Janus particles as an emulsion stabilizer, a phase change microstructure can be obtained through a sol-gel reaction at the water-oil interface. Capsules can obtain phase-change microcapsules based on inorganic shell layers with adjustable phase-change temperature and high enthalpy retention rate, and can solve the above-mentioned problems, thereby completing the present invention.

The present invention has been completed based on the above findings. That is, the present invention is as follows.

[1] A phase-change microcapsule based on an inorganic shell layer, comprising: a phase-change core material, and a composite wall material covering the phase-change core material,

Wherein, the composite wall material is formed from a wall material composition comprising Janus particles and shell inorganic matter.

[2] The phase-change microcapsules according to [1], wherein the Janus particles include inorganic-polymer Janus particles, polymer-polymer Janus particles, or inorganic-inorganic Janus particles.

[3] The phase change microcapsules according to [1] or [2], wherein the shell inorganic substance is obtained by a sol-gel reaction at a water-oil interface,

Preferably, the shell inorganic substance includes at least one selected from the group consisting of silicon dioxide, titanium dioxide, zirconium dioxide, tin dioxide, aluminium oxide and boron trioxide.

[4] The phase-change microcapsule according to any one of [1] to [3], wherein the phase-change core material is formed of a phase-change composition containing a phase-change material including a selected At least one selected from the group consisting of hydrocarbon-based compounds, fatty acid-based compounds, alcohol-based compounds, and ester-based compounds.

[5] The phase-change microcapsule according to [4], wherein the hydrocarbon-based compound includes a hydrocarbon-based compound selected from the group consisting of aliphatic hydrocarbon-based compounds having 8 to 100 carbon atoms, and aromatic hydrocarbon-based compounds having 6 to 120 carbon atoms , at least one of the group consisting of alicyclic hydrocarbyl compounds having 6 to 100 carbon atoms and paraffins,

The fatty acid compound includes at least one selected from the group consisting of capric acid, lauric acid, tetradecanoic acid, pentadecanoic acid, stearic acid and eicosanoic acid,

The alcohol compound includes at least one selected from the group consisting of butane erythritol, dodecanol, tetradecanol, hexadecanol and erythritol,

The ester compound includes at least one selected from the group consisting of cellulose laurate and cetyl stearate.

[6] The phase change microcapsules according to any one of [1] to [5], wherein the phase change latent heat of the phase change microcapsules is 20 to 250 J/g,

Preferably, the enthalpy retention rate of the phase change microcapsules is 20-99%,

Preferably, the phase transition temperature of the phase transition microcapsules is -50 to 150°C,

Preferably, the average particle size of the phase change microcapsules is 0.1-500 μm.

[7] The method for producing a phase-change microcapsule based on an inorganic shell layer according to any one of [1] to [6], comprising:

(a) preparation of dispersed phase: the inorganic precursor is dissolved in the molten phase change material, and the dispersed system is used as the dispersed phase;

(b) Preparation of continuous phase: disperse the Janus particles in water, adjust the pH value to 2-12, and use the dispersion system as the continuous phase;

(c) dispersing the dispersed phase obtained in the step (a) in the continuous phase obtained in the step (b) to form a Pickering emulsion; and

(d) subjecting the Pickering emulsion obtained in the step (c) to a sol-gel reaction at the water-oil interface under normal temperature or heating conditions to obtain the phase-change microcapsules.

[8] The production method according to [7], wherein, in the step (a), the phase change material includes a compound selected from the group consisting of hydrocarbon-based compounds, fatty acid-based compounds, alcohol-based compounds, and ester-based compounds at least one of the

Preferably, the inorganic precursor comprises at least one selected from the group consisting of silicon alkoxide, titanium alkoxide, tin alkoxide, zirconium alkoxide, aluminum alkoxide and boric acid,

Preferably, the mass ratio of the inorganic precursor to the phase change material is 0.1:100-50:100, preferably 0.5:100-25:100.

[9] The production method according to [8], wherein the inorganic precursor includes methyl orthosilicate, ethyl orthosilicate, glycidyltrimethoxysilane, and phenyltriethoxysilane Silane, aminopropyltrimethoxysilane, phenyltrimethoxysilane, n-octyltriethoxysilane, tetra-n-butyl titanate, tetraisopropyl titanate, tetrabutyl stannate, tetrazirconate At least one selected from the group consisting of butyl ester, triisopropyl aluminate, tribenzyl aluminate, and boric acid.

[10] The production method according to [7], wherein, in the step (b), the concentration of the Janus particles is 0.05 to 5%,

Preferably, the Janus particles include inorganic-polymeric Janus particles, polymer-polymeric Janus particles or inorganic-inorganic Janus particles.

[11] The production method according to [7], wherein, in the step (c), the volume ratio of the dispersed phase to the continuous phase is 1:1 to 1:100, preferably 1:1 ~1:50,

Preferably, the Pickering emulsion is formed by high shear emulsification or ultrasonic emulsification,

Preferably, the shearing speed of the high-speed shearing emulsification is 1000-25000 rpm, and the shearing time is 0.5-30 min,

Preferably, the ultrasonic frequency of the ultrasonic emulsification is 1000-40000 Hz, and the ultrasonic emulsification time is 10-60 min.

[12] The production method according to [7], wherein, in the step (d), the reaction temperature of the sol-gel reaction at the water-oil interface is 23 to 100° C., and the reaction time is 0.5 to 100° C. 72h.

[13] The manufacturing method according to [7], wherein the manufacturing method further comprises:

(e) a post-processing step, in which the phase-change microcapsules obtained in the step (d) are separated, washed and dried.

[14] The inorganic shell-based phase-change microcapsules according to any one of [1] to [7] are used in textile materials, building energy-saving materials, thermal management of electronic components and materials in the fields of waste heat recovery, The application of space thermal protection materials, weapon equipment warehouse wall temperature control materials or wearable equipment materials in the military field.

effect of invention

The invention uses Janus particles as emulsion stabilizers, uses Janus particles to stabilize the phase change material emulsion in water, obtains phase change microcapsules based on inorganic shell layers through sol-gel reaction at the water-oil interface, and realizes phase change core materials. At the same time, as part of the wall material, Janus particles participate in the preparation of phase change microcapsules, so that phase change microcapsules based on inorganic shell layers with stable structure, stable performance and controllable cost can be obtained.

The phase-change microcapsules based on the inorganic shell layer of the present invention have the characteristics of controllable phase-change temperature, high heat storage density and high enthalpy retention rate, and can excellently take into account the encapsulation effect and the enthalpy retention rate.

In addition, the manufacturing method of the phase change microcapsule based on the inorganic shell layer of the present invention can freely adjust the phase change temperature of the phase change material, and can efficiently control the ratio of the phase change material and Janus particles, so as to realize the phase change microcapsule well. Controllable in structure and composition. In addition, the manufacturing method of the phase-change microcapsules of the present invention has the advantages of simple process, short production period, high raw material conversion rate, convenient operation, and has the prospect of industrial mass production. Moreover, the raw materials are non-polluting and meet the needs of environmental friendliness.

Description of drawings

FIG. 1 is a partial flow chart of a manufacturing method of an inorganic shell-based phase change microcapsule according to an exemplary embodiment of the present invention.

2 is a scanning electron microscope image of SiO ₂ -PS Janus particles in Example 1 of the present invention.

FIG. 3 is a scanning electron microscope image under different magnifications of the phase-change microcapsules according to Example 1 of the present invention.

4 is a scanning electron microscope image of the shell layer of the phase-change microcapsule according to Example 1 of the present invention.

5 is a scanning electron microscope image of SiO ₂ -PS Janus particles in Example 2 of the present invention.

FIG. 6 is a scanning electron microscope image under different magnifications of the phase-change microcapsules according to Example 2 of the present invention.

7 is a scanning electron microscope image of the shell layer of the phase change microcapsule according to Example 2 of the present invention.

Detailed ways

Hereinafter, the content of the present invention will be described in detail. The description of the technical features described below is based on typical embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted:

In the present specification, the numerical range represented by "numerical value A to numerical value B" means a range including numerical values A and B at the endpoints.

In this specification, the numerical range expressed using "above" or "below" means a numerical range including this number.

In this specification, the meaning expressed by "may" includes both the meaning of performing a certain processing and not performing a certain processing.

In this specification, the use of "optional" or "optional" means that certain substances, components, execution steps, application conditions and other factors are used or not used.

In this specification, the unit names used are all international standard unit names, and if there is no special statement, the used "%" means weight or mass percentage.

In this specification, unless otherwise stated, the "particle size" used refers to the "average particle size", which can be measured by a commercial particle size analyzer.

In this specification, references to "some specific/preferred embodiments", "other specific/preferred embodiments", "embodiments", etc. refer to the specific elements described in relation to the embodiment (eg, features, structures, properties, and/or characteristics) are included in at least one embodiment described herein, and may or may not be present in other embodiments. Additionally, it should be understood that the described elements may be combined in any suitable manner in the various embodiments.

<Phase Change Microcapsules Based on Inorganic Shells>

The phase-change microcapsule based on the inorganic shell layer of the present invention comprises: a phase-change core material, and a composite wall material covering the phase-change core material,

Wherein, the composite wall material is formed from a wall material composition comprising Janus particles and shell inorganic matter.

In the present invention, the phase-change core material is encapsulated in the composite wall material, and the composite wall material of the present invention is formed from the wall material composition comprising Janus particles and shell inorganic substances, so that an inorganic-based inorganic material with stable structure and performance can be obtained. phase change microcapsules in the shell layer.

The Janus particles used in the present invention have strong design properties and can meet various industrial design requirements. In addition, Janus particles have extremely strong emulsifying properties, and the different physical and chemical properties at both ends can reduce the water-oil interfacial energy like an emulsifier. Moreover, Janus particles can exhibit Pickering effect at the water-oil interface like traditional nanoparticles. Therefore, Janus particles combine the advantages of traditional emulsifiers and nanoparticles to obtain a very stable emulsion in a very small amount.

In addition, the present invention utilizes Janus particles to assemble at the two-phase interface, obtains phase-change microcapsules based on inorganic shell layers through sol-gel reaction at the water-oil interface, and the obtained wall material is composed of inorganic materials including Janus particles and shell layers. The composition of the wall material of the material is formed, which can combine the advantages of the organic wall material and the inorganic wall material. The present invention can obtain phase change microcapsules with stable structure, stable performance and controllable cost by using the wall material composition comprising Janus particles and shell inorganic substances to form the wall material.

In some preferred embodiments, the average particle size of the inorganic shell-based phase change microcapsules of the present invention is 0.1-500 μm, preferably 1-250 μm, more preferably 10-100 μm. By controlling the average particle size of the phase change microcapsules within the above range, good interfacial compatibility can be obtained, and the enthalpy retention rate is high, which can further improve the thermal conductivity and expand its application fields and occasions.

In some preferred embodiments, the phase transition temperature of the inorganic shell-based phase transition microcapsules of the present invention is -50-150°C, preferably 10-120°C, more preferably 20-90°C. By making the phase transition temperature of the phase transition microcapsules fall within the above range, it can be more beneficial to applications such as energy allocation, temperature control, energy absorption, and memory storage in actual production and life.

In some preferred embodiments, the enthalpy retention rate of the inorganic shell-based phase change microcapsules of the present invention is 20-99%, preferably 50-97%, more preferably 75-95%. Compared with the phase-change microcapsules prepared by the traditional method, the phase-change microcapsules based on the inorganic shell layer of the present invention have a higher enthalpy retention rate, so that the phase-change microcapsules based on the inorganic shell layers of the present invention can absorb water during operation. More heat is released, so that the phase change microcapsule of the present invention has a wide range of applications in the fields of aerospace, construction, automobile, environmental protection, textile and clothing and the like.

The enthalpy retention rate of the phase change microcapsule based on the inorganic shell layer of the present invention is numerically similar to the content of the phase change material, and can be calculated by the melting enthalpy or the crystallization enthalpy, and the calculation method is as follows:

Enthalpy retention rate = ΔH _m /ΔH _m0 ×100%;

Enthalpy retention rate = ΔH _c /ΔH _c0 ×100%;

Among them, ΔH _m0 is the melting enthalpy of the phase change material, ΔH _m is the melting enthalpy of the obtained phase change microcapsules, ΔH _c0 is the crystallization enthalpy of the phase change material, and ΔH _c is the obtained crystallization enthalpy of the phase change microcapsules.

In some preferred embodiments, the phase transition latent heat of the inorganic shell-based phase transition microcapsules of the present invention is 20-250 J/g, preferably 30-240 J/g, more preferably 100-230 J/g, and further It is preferably 110 to 220 J/g. By making the phase-change latent heat of the phase-change microcapsules fall within the above range, a higher latent heat storage amount can be obtained.

Hereinafter, each configuration of the inorganic shell-based phase-change microcapsules constituting the present invention will be described in detail.

(composite wall material)

The composite wall material of the present invention is formed from a wall material composition comprising Janus particles and shell inorganics.

In the present invention, the composite wall material is prepared by the sol-gel reaction at the water-oil interface, and the dispersed phase change material is dissolved with an inorganic precursor. The inorganic precursor is oil-soluble. When it contacts the interface The sol-gel reaction occurs when the water is in the form of a cross-linked network. Since the cross-linked network is hydrophilic, it will phase-separate from the phase change material and deposit on the water-oil interface to form a shell layer. At the same time, the shell layer coats the Janus particles as emulsion stabilizer, thereby forming the composite profile wall material of the present invention.

In some preferred embodiments, the composite wall material of the present invention is composed of Janus particles and shell inorganics.

[Janus Granules]

In the present invention, the term "Janus particle" refers to a Janus particle in a broad sense in the art, that is, it can be not only asymmetric in structure and morphology (anisotropy), but also asymmetric in composition. Or both.

In some preferred embodiments of the present invention, the Janus particles comprise inorganic-polymers such as silica-polystyrene ( _SiO2 -PS) Janus particles, silica-polyacrylamide ( _SiO2 -PAM) Janus particles, and the like Material type Janus particles; such as polystyrene-polymethyl methacrylate (PS-PMMA) Janus particles, polystyrene-polyacrylonitrile (PS-PAN) Janus particles, polytrihydroxyacrylate-poly(polyethylene glycol) Alcohol diacrylate) (PTMPTA-POEGDA) Janus particles, etc. polymer-polymer type Janus particles; or such as silica-iron tetroxide (SiO ₂ -Fe ₃ O ₄ ) Janus particles, silica-silver Inorganic-inorganic Janus particles such as (SiO ₂ -Ag) Janus particles. Among these, inorganic-polymer-type Janus particles or inorganic-inorganic-type Janus particles are preferred. In some preferred embodiments, the inorganic-inorganic Janus particles are preferably inorganic-metallic Janus particles or metal-metallic Janus particles.

In some preferred embodiments, the Janus particles of the present invention have a hydrophilic portion and a hydrophobic portion.

In some preferred embodiments, the hydrophilic portion of the Janus particles of the present invention may have hydroxyl groups (eg, alcoholic hydroxyl groups, silanol hydroxyl groups, phenolic hydroxyl groups, etc.), ether groups, amide groups, carboxyl groups, anhydrides or salts thereof, and the like.

In some embodiments, the hydrophilic portion of the Janus particles of the present invention may be composed of organic or inorganic substances. Examples of monomers forming the organic substance constituting the hydrophilic part include, without limitation, acrylic monomers, pyrrolidone-based monomers, acrylamide-based monomers, (poly)ethylene glycol-based monomers, (poly)propylene glycol-based monomers, and the like . These monomers may be used alone or in combination of two or more. Examples of inorganic substances constituting the hydrophilic portion include, without limitation, silica, silica, titania, alumina, and the like. These inorganic substances may be used alone or in combination of two or more. In some preferred embodiments, the hydrophilic portion of the Janus particles of the present invention preferably comprises inorganic species, more preferably silica.

In some embodiments, the hydrophobic portion of the Janus particles of the present invention includes organic substances. Examples of monomers forming the organic substance constituting the hydrophobic portion include, without limitation, styrene-based monomers (eg, styrene, p-methylstyrene, α-methylstyrene, etc.), (meth)acrylate-based monomers Monomers (for example, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, etc.), silane-based monomers, siloxane-based monomers, olefin-based monomers, acetal Monomers, etc. These monomers may be used alone or in combination of two or more. In some preferred embodiments, the hydrophobic portion of the Janus particles of the present invention preferably comprises a polystyrene-based resin or a poly(meth)acrylate-based resin.

In some preferred embodiments, the combination of a hydrophilic part and a hydrophobic part (hydrophilic part/hydrophobic part) of the Janus particles of the present invention can be, for example, silica/polystyrene, silica /Poly(meth)acrylate-based monomer, silica/polystyrene-(meth)acrylate-based monomer, silica/polystyrene-divinylbenzene, silica/poly(meth)acrylate base) acrylate monomers-divinylbenzene, silica/polystyrene-(meth)acrylate monomers-divinylbenzene, titanium dioxide/polystyrene, titanium dioxide/polystyrene-divinyl base benzene, titanium dioxide/poly(meth)acrylate-based monomer-divinylbenzene, etc.

Specific examples of Janus particles include silica-polystyrene Janus particles (SiO ₂ -PS), silica-polyacrylamide Janus particles (SiO ₂ -PAM), polystyrene-polyacrylonitrile Janus particles (PS-PAN), polystyrene-polyacrylate Janus particles (PS-polyacrylate), silica-silver Janus particles (SiO ₂ -Ag), and the like.

The form of the Janus particles of the present invention is not particularly limited, and examples thereof include spherical, snowman, dumbbell, rod, butterfly, mushroom, bullet, half-raspberry, raspberry, cone, flake, and columnar shapes. shape, hamburger shape and other types. From the viewpoint of better achieving the technical effect of the present invention, the Janus particles of the present invention are preferably Janus particles that are asymmetric in structure and morphology, for example, those having a snowman shape, a dumbbell shape, a half raspberry shape, and a mushroom shape can be listed. particles of equal shape.

In some preferred embodiments, the Janus particles in the present invention are preferably Janus particles having a snowman shape. In the present invention, the term "snowman shape" refers to a three-dimensional structure formed by stacking two spheres (or approximate spheres) with different sizes in a partially overlapping manner (as shown in FIG. 2 ).

In some preferred embodiments, the size of the Janus particles of the present invention is preferably 20-2000 nm, more preferably 100-1000 nm. When the Janus particles of the present invention are snowman-shaped Janus particles, the diameter ratio of the two spheres constituting the "snowman-shaped" is preferably 1:9 to 9:1, and more preferably 1:4 to 4:1.

The preparation method of the Janus particles is not particularly limited, and the Janus particles can be prepared by methods commonly used in the art. For example, it can be prepared by surface selective modification method, emulsion polymerization method, seed emulsion polymerization method, phase separation method, microfabrication and self-assembly, dispersion polymerization method and the like.

In some preferred embodiments, for the preparation method of the Janus particles of the present invention, for example, reference can be made to the preparation method of Janus particles disclosed in Chinese Patent Application CN105440218A. Specifically, the preparation method of the Janus particles of the present invention includes the following steps: dispersing the polymer particles in water to obtain a seed solution; emulsifying and adding a silane coupling agent, an emulsifier, an initiator, etc. into the seed solution, under mechanical stirring Carry out a polymerization reaction to obtain a suspension of Janus particles; the obtained suspension of Janus particles is spray-drying or freeze-drying to obtain Janus particles.

[Shell inorganic matter]

In the present invention, the inorganic matter in the shell layer is obtained by the sol-gel reaction of the inorganic matter precursor at the water-oil interface. The inorganic precursors encapsulated in the phase change material migrate to the water-oil interface during the reaction process, and undergo a hydrolysis-condensation reaction to form inorganic oxides, and finally deposit a stable inorganic material shell layer at the water-oil interface.

Examples of the inorganic precursors include silicon alkoxides, titanium alkoxides, tin alkoxides, zirconium alkoxides, aluminum alkoxides, boric acid, and the like. These may be used individually by 1 type, or may be used in combination of 2 or more types. Among these, silicon alkoxide, titanium alkoxide or aluminum alkoxide is preferable.

Specific examples of the inorganic precursor include methyl orthosilicate, ethyl orthosilicate, glycidyltrimethoxysilane, phenyltriethoxysilane, and aminopropyltrimethoxysilane. , phenyltrimethoxysilane, n-octyltriethoxysilane, tetra-n-butyl titanate, tetraisopropyl titanate, tetrabutyl stannate, tetrabutyl zirconate, triisopropyl aluminate, Tribenzyl aluminate, boric acid, etc. These may be used individually by 1 type, or may be used in combination of 2 or more types. In some preferred embodiments, the inorganic precursor is preferably methyl orthosilicate, ethyl orthosilicate, tetra-n-butyl titanate or triisopropyl aluminate, and the raw materials of these inorganic precursors are readily available, and The sol-gel reaction is controllable, which can ensure the product stability while controlling the preparation cost of phase change microcapsules.

In some preferred embodiments, the compounding amount of the inorganic precursor is 50 to 2500 parts by mass relative to 100 parts by mass of the Janus particles. By setting the content ratio of the inorganic precursor within the above-mentioned range, it is possible to obtain a phase-change microcapsule in which the encapsulation effect and the enthalpy retention ratio are balanced.

In some preferred embodiments, the shell inorganic material includes at least one selected from the group consisting of silicon dioxide, titanium dioxide, zirconium dioxide, tin dioxide, aluminum oxide, and boron oxide.

(phase change core material)

In the present invention, the phase-change core material is formed from a phase-change composition comprising a phase-change material.

As used herein, the term "phase change material" refers to a material that has the ability to absorb or release heat in or within a temperature stable range to modulate heat transfer. The temperature stable range may include a specific transition temperature or a range of transition temperatures. In some cases, the phase change material may be able to inhibit heat transfer for a period of time when the phase change material absorbs or releases heat, typically when the phase change material undergoes a transition between two states. This effect is typically temporary and does not occur until the latent heat of the phase change material is absorbed or released during the heating or cooling process. Heat can be stored or removed from the phase change material, and the phase change material can typically be efficiently replenished by a source that emits or absorbs heat. For some embodiments, the phase change material may be a mixture of two or more materials. By selecting two or more different materials and forming a mixture, the temperature stability range can be adjusted for any desired application. The resulting mixture, when incorporated into the phase change microcapsules described herein, can exhibit two or more different transition temperatures or a single modified transition temperature.

In the present invention, the phase change material includes hydrocarbon compounds, fatty acid compounds, alcohol compounds, ester compounds and the like. These may be used individually by 1 type, or may be used in combination of 2 or more types. Among these, the phase change material is preferably a hydrocarbon compound, which can effectively improve thermal conductivity. In addition, when a hydrocarbon compound is used, it is easy to obtain, and a phase-change microcapsule with stable characteristics can be obtained by using an inexpensive material.

Examples of the hydrocarbon compound include aliphatic hydrocarbon compounds having 8 to 100 carbon atoms (preferably an aliphatic hydrocarbon compound having 10 to 80 carbon atoms, more preferably aliphatic having 15 to 50 carbon atoms) aliphatic hydrocarbon-based compounds, more preferably an aliphatic hydrocarbon-based compound having 18 to 30 carbon atoms), an aromatic hydrocarbon-based compound having 6 to 120 carbon atoms (preferably an aromatic hydrocarbon-based compound having 8 to 100 carbon atoms, more It is preferably an aromatic hydrocarbon compound having 10 to 50 carbon atoms, more preferably an aromatic hydrocarbon compound having 12 to 30 carbon atoms), an alicyclic hydrocarbon compound having 6 to 100 carbon atoms (preferably having 6 to 80 carbon atoms alicyclic hydrocarbon compound, more preferably 6 to 50 carbon atom alicyclic hydrocarbon compound, further preferably 6 to 30 carbon atom alicyclic hydrocarbon compound), paraffin (melting point 5～80℃) and so on.

The aliphatic hydrocarbon-based compound having 8 to 100 carbon atoms may be a straight-chain or branched-chain aliphatic hydrocarbon-based compound, examples of which include, but are not limited to, n-octadecane, n-nonadecane, n-eicosane, n-hexadecane alkane, n-docosane, n-docosane, n-tetracosane, n-pentacosane, n-hexadecane, n-heptadecane, n-octacosane, etc.

Examples of aromatic hydrocarbon-based compounds having 6 to 120 carbon atoms include, but are not limited to, benzene, naphthalene, biphenyl, o-terphenyl, n-terphenyl, and the like. In some embodiments, the aromatic hydrocarbyl compound having 6 to 120 carbon atoms may be a substituted aromatic hydrocarbyl compound having 6 to 100 carbon atoms, preferably a C ₁ -C ₄₀ alkyl substituted aromatic hydrocarbyl compound having 6 to 100 carbon atoms Aromatic hydrocarbon compounds of 100 carbon atoms. Examples of _C1 - _C40 alkyl substituted aromatic hydrocarbyl compounds include, but are not limited to, dodecylbenzene, tetradecylbenzene, hexadecylbenzene, hexylnaphthalene, decylnaphthalene, and the like.

Examples of alicyclic hydrocarbon-based compounds having 6 to 100 carbon atoms include, but are not limited to, cyclohexane, cyclooctane, cyclodecane, and the like.

As the fatty acid compound, it is preferably saturated or unsaturated C ₆ -C ₃₀ fatty acid, examples of which include but are not limited to caprylic acid, capric acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, octadecanoic acid, lauric acid, meat Myristic acid, palmitic acid, stearic acid, behenic acid, etc. These may be used individually by 1 type, or may be used in combination of 2 or more types.

As the alcohol compound, it is preferably a C ₃ -C ₂₀ aliphatic alcohol, examples of which include but are not limited to glycerol, butane erythritol, dodecanol, tetradecanol, cetyl alcohol, erythritol, stearyl alcohol, Oleyl alcohol, mixtures such as coconut fatty alcohol, and so-called oxo alcohols obtained by hydroformylation of alpha-olefins and further reaction, etc. These may be used individually by 1 type, or may be used in combination of 2 or more types.

As the ester compound, C ₁ -C ₃₀ alkyl esters of fatty acids are preferred, examples of which include but are not limited to cetyl stearate, cellulose laurate, propyl palmitate, methyl stearate, palm Methyl acid, etc. These may be used individually by 1 type, or may be used in combination of 2 or more types.

The choice of phase change material may depend on the latent heat and transition temperature of the phase change material. The latent heat of a phase change material is typically related to its ability to reduce or eliminate heat transfer. In some cases, the latent heat of the phase change material can be at least about 40 J/g, such as at least about 50 J/g, at least about 60 J/g, at least about 70 J/g, preferably at least about 80 J/g, particularly preferably at least about 90 J/g g, and most preferably at least about 100 J/g. Thus, for example, the latent heat of the phase change material may range from 40 to 400 J/g, preferably 60 to 400 J/g, particularly preferably 80 to 400 J/g, and most preferably 100 to 400 J/g. The transition temperature of the phase change material is typically related to the desired temperature or desired temperature range that can be maintained by the phase change material. In some cases, the transition temperature range of the phase change material may be -10 to 110°C, such as 0 to 100°C, 0 to 50°C, 10 to 50°C, preferably 15 to 45°C, particularly preferably 22 to 40°C, and Most preferably, it is 22 to 28°C.

<Method for producing phase-change microcapsules based on inorganic shell layers>

The manufacturing method of the phase change microcapsule of the present invention comprises:

(a) preparation of dispersed phase: the inorganic precursor is dissolved in the molten phase change material, and the dispersed system is used as the dispersed phase;

(b) Preparation of continuous phase: disperse the Janus particles in water, adjust the pH value to 2-12, and use the dispersion system as the continuous phase;

(c) dispersing the dispersed phase obtained in the above step (a) in the continuous phase obtained in the above step (b) to form a Pickering emulsion; and

(d) subjecting the Pickering emulsion obtained in the above step (c) to a sol-gel reaction at the water-oil interface under normal temperature or heating conditions to obtain the phase change microcapsules.

In addition, in addition to the above-mentioned steps, optional pre-treatment and post-treatment may be used in combination according to actual production conditions or needs without affecting the effect of the present invention.

In a preferred embodiment of the present invention, the method for producing phase-change microcapsules of the present invention further comprises: (e) a post-processing step, in which the phase-change microcapsules obtained in the above step (d) are separated, washed and dried.

FIG. 1 is a partial flow chart of a manufacturing method of an inorganic shell-based phase change microcapsule according to an exemplary embodiment of the present invention. As shown in FIG. 1 , after preparing the dispersed phase, in the preparation of the continuous phase described in the step (b), the Janus particles are dispersed in water, and the dispersion system is used as the continuous phase. Then, the dispersed phase is dispersed in the continuous phase to form a Pickering emulsion, and the sol-gel reaction at the water-oil interface is carried out under normal temperature or heating conditions to obtain phase change microcapsules based on the inorganic shell layer.

Each of the above steps will be described in detail below.

Process (a)

In the step (a) of the present invention, the dispersed phase is prepared: the inorganic precursor is dissolved in the molten phase change material, and the dispersed system is used as the dispersed phase.

Examples of the inorganic precursors include silicon alkoxides, titanium alkoxides, tin alkoxides, zirconium alkoxides, aluminum alkoxides, boric acid, and the like. These may be used individually by 1 type, or may be used in combination of 2 or more types. Among these, silicon alkoxide, titanium alkoxide or aluminum alkoxide is preferable.

Specific examples of the inorganic precursor include methyl orthosilicate, ethyl orthosilicate, glycidyltrimethoxysilane, phenyltriethoxysilane, and aminopropyltrimethoxysilane. , phenyltrimethoxysilane, n-octyltriethoxysilane, tetra-n-butyl titanate, tetraisopropyl titanate, tetrabutyl stannate, tetrabutyl zirconate, triisopropyl aluminate, Tribenzyl aluminate, boric acid, etc. These may be used individually by 1 type, or may be used in combination of 2 or more types. In some preferred embodiments, the inorganic precursor is preferably methyl orthosilicate, ethyl orthosilicate, tetra-n-butyl titanate or triisopropyl aluminate, and the raw materials of these inorganic precursors are readily available, and The sol-gel reaction is controllable, which can ensure the product stability while controlling the preparation cost of phase change microcapsules.

As a phase change material, a hydrocarbon type compound, a fatty acid type compound, an alcohol type compound, an ester type compound etc. are mentioned, for example. These may be used individually by 1 type, or may be used in combination of 2 or more types. Among these, it is preferable that the phase change material is a hydrocarbon compound from the viewpoint of further increasing the phase change enthalpy value.

Examples of the hydrocarbon-based compound, fatty acid-based compound, alcohol-based compound, and ester-based compound include the same hydrocarbon-based compound, fatty acid-based compound, alcohol-based compound, and ester-based compound used in the phase-change material for the aforementioned phase-change microcapsules. The substances that can be used can also be listed in the same way.

In the present invention, the mass ratio of the inorganic precursor and the phase change material is preferably 0.1:100 to 50:100, preferably 0.5:100 to 25:100. By setting the mass ratio of the inorganic precursor to the phase-change material within the above-mentioned range, it is possible to obtain phase-change microcapsules with a relatively balanced encapsulation effect and enthalpy retention rate.

In some preferred embodiments, the content of the inorganic precursor is preferably 0.5-25 parts by mass, more preferably 2-15 parts by mass, relative to 100 parts by mass of the phase change material.

If the compounding amount of the inorganic precursor is 0.5 parts by mass or more, phase change microcapsules excellent in mechanical strength and toughness can be obtained well. In addition, when the compounding amount of the inorganic precursor is 25 parts by mass or less, the enthalpy retention rate of the phase change microcapsules of the present invention can be further improved.

In the present invention, the formulation of the dispersed phase can be carried out by conventional methods. For example, it is possible to easily prepare a dispersed phase by mixing the above-mentioned components and performing sufficient stirring and mixing. There is no particular limitation on the way of adding the inorganic precursor, and the inorganic precursor can be added at one time or in batches.

The preparation time and preparation temperature are not particularly limited. In some preferred embodiments of the present invention, from the viewpoint of thorough mixing to obtain an excellent dispersed phase, preferably higher than the melting temperature of the phase change material, the inorganic precursor is dissolved in the molten phase change material, and the preparation time is 1 to 30 minutes.

Process (b)

In the step (b) of the present invention, the continuous phase is prepared: the Janus particles are dispersed in water, the pH value thereof is adjusted to 2-12, and the dispersion system is used as the continuous phase.

As the Janus particles, the same ones as the Janus particles used in the composite wall material of the phase-change microcapsules described above can be mentioned, and the same aspects can be mentioned as the modes that can be used.

In the present invention, the concentration of Janus particles, the difference in the size of the two ends, the difference in the hydrophilicity and hydrophobicity of the two ends, etc. all affect the prepared Pickering emulsion. In the step (b) of the present invention, the concentration of the Janus particles is preferably 0.05 to 5%, and more preferably 0.2 to 2%. The size ratio of both ends of the Janus particles is preferably 0.2:1 to 2:1, more preferably 0.5:1 to 1.5:1. In some preferred embodiments, the Janus particles are preferably inorganic-polymeric Janus particles.

In the present invention, soluble salts such as sodium chloride, potassium chloride, barium chloride, calcium chloride, sodium carbonate, sodium bicarbonate, sodium sulfate, potassium sulfate, sodium nitrate, potassium nitrate and calcium nitrate can be added by adding ) regulates the surface charge state of Janus particles.

In the present invention, in order to better control the sol-gel reaction, the pH value of the system is adjusted to 2-12, preferably 3-10.

In the present invention, the preparation of the continuous phase can be carried out by conventional methods. For example, the formulation of the continuous phase is carried out by mixing the above-mentioned ingredients and dispersing them uniformly by ultrasonication.

The preparation time and preparation temperature are not particularly limited. In some preferred embodiments of the present invention, from the viewpoint of uniform dispersion to obtain an excellent continuous phase, the Janus particles are preferably dispersed in water at room temperature (eg, 20-25° C.), and the preparation time is 1-30 min .

Process (c)

In the step (c) of the present invention, the dispersed phase obtained in the above step (a) is dispersed in the continuous phase obtained in the above step (b) to form a Pickering emulsion.

More specifically, in the step (c) of the present invention, the dispersed phase obtained in the above step (a) is dispersed in the continuous phase obtained in the above step (b), and with the assistance of a shearing machine, the Janus particles are It assembles at the two-phase interface and plays a role in emulsion stabilization to form Pickering emulsion.

In the step (c) of the present invention, the volume ratio of the dispersed phase to the continuous phase is preferably 1:1 to 1:100, and more preferably 1:1 to 1:50. By making the volume ratio of the dispersed phase to the continuous phase fall within the above range, it is possible to obtain a more stable emulsion, better control the size of the dispersed phase, and improve production efficiency.

In the step (c) of the present invention, the emulsification is preferably selected from high-speed shear emulsification or ultrasonic emulsification. In the case of using high-speed shearing emulsification, the shearing speed of high-speed shearing emulsification is in the range of 1000-25000rpm, and the shearing time is in the range of 0.5-30min. In the case of using ultrasonic emulsification, the ultrasonic frequency during ultrasonic emulsification is 1000-40000 Hz, and the time of ultrasonic emulsification is 10-60 min.

Process (d)

In the step (d) of the present invention, the Pickering emulsion obtained in the above step (c) is subjected to a sol-gel reaction at the water-oil interface at normal temperature (23-25° C.) or under heating conditions to obtain phase-change microcapsules .

According to the present invention, in the step (d), the conditions of the sol-gel reaction are usually determined by the selected inorganic precursor and the pH value of the system. Under the conditions of normal temperature (23-25°C), the reaction time is preferably 8-72 h, more preferably 12-48 h. Under heating conditions, the reaction temperature is preferably 40-100° C., more preferably 50-80° C., and the reaction time is preferably 0.5-72 h, more preferably 4-24 h.

Process (e)

In the step (e) of the present invention, the phase-change microcapsules obtained in the above-mentioned step (d) are separated, washed and dried.

The separation method is not particularly limited, and means such as centrifugation and suction filtration can be used alone or in combination according to the specific conditions of the actual system.

In some specific embodiments, in the step (e) of the present invention, the phase-change microcapsule mixing system mixed with Janus particles is centrifuged or suction filtered to obtain a solid-phase product, and then washed and dried to obtain the present invention. Invented phase change microcapsules.

In some specific embodiments of the present invention, a centrifuge can be used for centrifugation to separate the above-mentioned mixed system to obtain the phase-change microcapsules of the present invention. The centrifugation conditions are not particularly limited. For example, the centrifugation speed is 3,000 to 15,000 rpm, and the centrifugation time is 2 to 30 minutes. The suction filtration treatment can use a suction filtration device to separate the above mixed system to obtain the phase change microcapsules of the present invention. The suction filtration conditions are not particularly limited. For example, the pore size of the filter paper for suction filtration may be 50 to 500 μm.

The drying method is not particularly limited, and for example, conventional drying methods such as freeze drying and spray drying can be used.

<application>

The phase change microcapsule based on the inorganic shell layer of the present invention is used for textile materials, building energy-saving materials, materials in the fields of thermal management of electronic components and waste heat recovery, space thermal protection materials, weapons and equipment warehouse wall temperature control materials or military Application of wearable equipment materials in the field.

Example

Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited to these examples.

[The mass percentage of phase change material in phase change microcapsules]

Thermogravimetric analysis (TGA) was used to obtain the mass percentage of the phase change material in the phase change microcapsules. Specifically, the dried phase change microcapsules were placed in an alumina crucible and the thermogravimetric curve of the sample under air atmosphere was tested by TGA (TA Q500). The test temperature range is 25 to 800°C, and the heating rate is 10°C/min. Finally, the mass percentage of the phase change microcapsules can be obtained by comparing the thermal weight loss value of the phase change material with the mass of the original phase change microcapsules:

The mass percentage of the phase change material in the phase change microcapsules = m _PCM /m ₀ ×100%;

Among them, m _PCM is the thermal weight loss value of the phase change material, and m ₀ is the mass of the original phase change microcapsules.

[Enthalpy retention rate (heat storage retention rate)]

Differential scanning calorimetry (DSC) was used to analyze and test the enthalpy retention rate of phase change microcapsules. Specifically, the dried phase change microcapsules were placed in an aluminum crucible to test the melting phase transition enthalpy, crystallization phase transition enthalpy, melting phase transition temperature and crystallization phase transition temperature of the sample by DSC (TA Q2000). The test temperature range is 10 to 80 °C, and the temperature rise and fall rate is 10 °C/min. Finally, the enthalpy retention rate of the phase change microcapsules can be obtained by comparing the phase change point enthalpy of the phase change microcapsules with that of the original phase change material:

Enthalpy retention rate = ΔH _m /ΔH _m0 ×100%;

Enthalpy retention rate = ΔH _c /ΔH _c0 ×100%;

Among them, ΔH _m0 is the melting enthalpy of the phase change material, ΔH _m is the melting enthalpy of the obtained phase change microcapsules, ΔH _c0 is the crystallization enthalpy of the phase change material, and ΔH _c is the obtained crystallization enthalpy of the phase change microcapsules.

Example 1

Preparation of SiO ₂ - PS Janus Particles

0.15 g of azobisisobutyronitrile (AIBN) was dissolved in 15.00 g of divinylbenzene (DVB) and 0.15 g of sodium dodecyl sulfate (SDS) was dissolved in 800.00 g of water. The above two solutions were mixed and ultrasonically emulsified for 3 min to obtain DVB monomer emulsion. Then 25.00 g of freeze-dried HP-433 polystyrene (PS) hollow spheres were dispersed into the above monomer emulsion. Stir at room temperature for 8h to promote the swelling of PS hollow spheres with DVB. Subsequently, the temperature was raised to 70° C. and reacted for 12 h to obtain a cross-linked PS hollow sphere dispersion. Finally, the dry powder of seed balls was obtained by washing with ethanol and water and freeze-drying. 10.00 g of seed ball dry powder was dispersed in 200.00 g of water, and the temperature of the system was raised to 70°C. 6.00g of 3-(methacryloyloxy)propyltrimethoxysilane (MPS), 6.00g of 1wt% potassium persulfate (KPS) aqueous solution and 0.20g of SDS were added to 100.00g of water, phacoemulsification An MPS monomer emulsion is obtained. The MPS monomer emulsion was gradually dropped into the dispersion of seed balls within 30min, and the reaction was kept stirring for 24h. Subsequently, 10.00 mL of 28wt% ammonia water was added to the above mixed solution, and the reaction was continued for 1 h to ensure that the reaction was complete. The product was washed with ethanol and deionized water, and lyophilized to obtain _SiO2 -PS Janus particles.

The scanning electron microscope photograph of the SiO ₂ -PS Janus particles produced above is shown in FIG. 2 .

Preparation of Phase Change Microcapsules Based on Inorganic Shells

2g of tetraethyl orthosilicate, 0.2g of glycidyl trimethoxysilane and 0.2g of phenyltriethoxysilane were added to 10g of molten paraffin (T _m = 50-52°C), mixed well and used as a dispersion Mutually. 0.2 g of the SiO ₂ -PSJanus particles prepared above and 1 g of sodium chloride were added to 100 g of water as a continuous phase, and the pH of the continuous phase was adjusted to 3-4 with a concentration of 0.2 M hydrochloric acid. Add the dispersed phase to the continuous phase, use a high-speed shear emulsifier to shear and emulsify at 12,000 rpm for 3 minutes, transfer the obtained emulsion to a three-necked bottle, and react at 70° C. for 12 hours under mechanical stirring. Phase change microcapsules are obtained by separation, washing and further drying.

Figure 3 shows the scanning electron microscope photos of the phase-change microcapsules based on the inorganic shell layer prepared in this example under different magnifications. It can be seen from FIG. 3 that the phase change microcapsules based on the inorganic shell layer prepared in this example are relatively uniform in particle size and have good encapsulation properties. Further, it can be seen from the enlarged view shown in (b) of FIG. 3 that the phase change core material is well encapsulated in the composite wall material. From Figure 4, the composite wall material formed by Janus particles and shell inorganic matter was confirmed.

The particle size of the phase-change microcapsules based on the inorganic shell layer prepared in this example is 27.3±6.8 μm; the mass percentage of the phase-change material in the phase-change microcapsules is 80.9%; the phase-change microcapsules based on the inorganic shell layer are The enthalpy retention rate of 80.1%; the phase transition temperatures of the phase change microcapsules based on the inorganic shell layer are 36.0 ℃ and 54.8 ℃; the phase change latent heat of the phase change microcapsules based on the inorganic material shell layer is 142.7 J/g.

Example 2

Preparation of SiO ₂ - PS Janus Particles

_SiO2 -PS Janus particles were prepared similarly to Example 1, except that the amount of 3-(methacryloyloxy)propyltrimethoxysilane (MPS) used was changed to obtain larger silica ends. The specific steps are as follows: 0.15 g of azobisisobutyronitrile (AIBN) is dissolved in 15.00 g of divinylbenzene (DVB), and 0.15 g of sodium dodecyl sulfate (SDS) is dissolved in 800.00 g of water. The above two solutions were mixed and ultrasonically emulsified for 3 min to obtain DVB monomer emulsion. Then 25.00 g of freeze-dried HP-433 polystyrene (PS) hollow spheres were dispersed into the above monomer emulsion. Stir at room temperature for 8h to promote the swelling of PS hollow spheres with DVB. Subsequently, the temperature was raised to 70° C. and reacted for 12 h to obtain a cross-linked PS hollow sphere dispersion. Finally, the dry powder of seed balls was obtained by washing with ethanol and water and freeze-drying. 10.00 g of seed ball dry powder was dispersed in 200.00 g of water, and the temperature of the system was raised to 70°C. 9.00g of 3-(methacryloyloxy)propyltrimethoxysilane (MPS), 9.00g of 1wt% potassium persulfate (KPS) aqueous solution and 0.20g of SDS were added to 100.00g of water, phacoemulsification An MPS monomer emulsion is obtained. The MPS monomer emulsion was gradually dropped into the dispersion of seed balls within 30min, and the reaction was kept stirring for 24h. Subsequently, 10.00 mL of 28wt% ammonia water was added to the above mixed solution, and the reaction was continued for 1 h to ensure that the reaction was complete. The product was washed with ethanol and deionized water, and lyophilized to obtain _SiO2 -PS Janus particles.

The scanning electron microscope photograph of the SiO ₂ -PS Janus particles produced above is shown in FIG. 5 .

Preparation of Phase Change Microcapsules

1 g of tetrabutyl titanate, 0.2 g of aminopropyltrimethoxysilane and 0.2 g of n-octyltriethoxysilane were added to 10 g of molten hexadecane, mixed well and used as a dispersed phase. 0.5 g of the SiO ₂ -PS Janus particles produced above and 1 g of sodium chloride were added to 100 g of water as a continuous phase, and the pH of the continuous phase was adjusted to 2.5 with a concentration of 2M hydrochloric acid. The dispersed phase was added to the continuous phase, and a high-speed shearing emulsifier was used for shearing and emulsification at 12,000 rpm for 5 min. The resulting emulsion was transferred to a three-necked bottle, and the reaction was carried out at room temperature for 12 hours under mechanical stirring. Phase change microcapsules are obtained by separation, washing and further drying.

Figure 6 shows the scanning electron microscope photos of the phase-change microcapsules based on the inorganic shell layer prepared in this example under different magnifications. It can be seen from FIG. 6 that the phase change microcapsules based on the inorganic shell layer prepared in this example are relatively uniform in particle size and have good encapsulation properties. Further, it can be seen from the enlarged view shown in (b) of FIG. 6 that the phase change core material is well encapsulated in the composite wall material. From Figure 7, the composite wall material formed by Janus particles and shell inorganic matter was confirmed.

The particle size of the phase change microcapsules based on the inorganic shell layer prepared in this example is 29.9±7.5 μm; the mass percentage of the phase change material in the phase change microcapsules is 82.6%; the phase change microcapsules based on the inorganic shell layer The enthalpy retention rate of 81.8%; the phase transition temperature of the phase change microcapsules based on the inorganic shell layer is 18.6 ℃; the phase change latent heat of the phase change microcapsules based on the inorganic material shell layer is 193.8J/g.

Various embodiments of the present disclosure have been described above, and the foregoing descriptions are exemplary, not exhaustive, and not limiting of the disclosed embodiments. Numerous modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein was chosen to best explain the principles of the various embodiments, the practical application or improvement over the technology in the marketplace, or to enable others of ordinary skill in the art to understand the various embodiments disclosed herein.

Industrial Availability

The phase-change microcapsules based on the inorganic shell layer of the invention have the characteristics of controllable phase-change temperature, high heat storage density, excellent thermal conductivity and high enthalpy retention rate, and can be widely used in textiles, building energy-saving, electronic component heating Management and waste heat recovery and other fields, as well as space thermal protection materials, weapon equipment warehouse wall temperature control, wearable equipment and other military fields. In addition, the manufacturing method of the phase change microcapsule based on the inorganic shell layer of the present invention has the advantages of simple process, short production period, high conversion rate of raw materials, convenient operation, and has the prospect of industrial mass production.

Claims (14)

1. Phase-change microcapsules based on an inorganic shell, characterized in that they comprise: a phase-change core material and a composite wall material coating the phase-change core material,

wherein the composite wall material is formed from a wall material composition comprising Janus particles and a shell inorganic substance.

2. The phase change microcapsule according to claim 1, wherein said Janus particles comprise inorganic-polymeric Janus particles, polymer-polymeric Janus particles, or inorganic-inorganic Janus particles.

3. The phase-change microcapsule according to claim 1 or 2, wherein the shell inorganic substance is obtained by a sol-gel reaction at an oil-water interface,

preferably, the shell inorganic substance includes at least one selected from the group consisting of silicon dioxide, titanium dioxide, zirconium dioxide, tin dioxide, aluminum oxide and boron trioxide.

4. The phase-change microcapsule according to any one of claims 1 to 3, wherein the phase-change core material is formed of a phase-change composition containing a phase-change material comprising at least one selected from the group consisting of hydrocarbon compounds, fatty acid compounds, alcohol compounds and ester compounds.

5. The phase-change microcapsule according to claim 4, wherein said hydrocarbon compound comprises at least one selected from the group consisting of an aliphatic hydrocarbon-based compound having 8 to 100 carbon atoms, an aromatic hydrocarbon-based compound having 6 to 120 carbon atoms, an alicyclic hydrocarbon-based compound having 6 to 100 carbon atoms, and paraffin wax,

the fatty acid-series compound includes at least one selected from the group consisting of capric acid, lauric acid, myristic acid, pentadecanoic acid, stearic acid, and arachidic acid,

the alcohol compound includes at least one selected from the group consisting of erythritol, dodecanol, tetradecanol, hexadecanol, and erythritol,

the ester compound includes at least one selected from the group consisting of cellulose laurate and cetyl stearate.

6. The phase-change microcapsule according to any one of claims 1 to 5, wherein said phase-change microcapsule has a latent heat of phase change of 20 to 250J/g,

preferably, the enthalpy retention rate of the phase-change microcapsule is 20-99%,

preferably, the phase change temperature of the phase change microcapsule is-50 to 150 ℃,

preferably, the average particle size of the phase-change microcapsule is 0.1-500 μm.

7. The method for producing phase change microcapsules based on an inorganic shell layer according to any one of claims 1 to 6, comprising:

(a) preparing a dispersed phase: dissolving an inorganic matter precursor in a molten phase-change material, and taking the dispersion system as a disperse phase;

(b) preparing a continuous phase: dispersing Janus particles in water, adjusting the pH value of the Janus particles to 2-12, and taking the dispersion system as a continuous phase;

(c) dispersing the dispersed phase obtained in the step (a) in the continuous phase obtained in the step (b) to form a Pickering emulsion; and

(d) and (c) carrying out sol-gel reaction on the Pickering emulsion obtained in the step (c) at a water-oil interface under normal temperature or heating conditions to obtain the phase-change microcapsule.

8. The production method according to claim 7, wherein in the step (a), the phase change material comprises at least one selected from the group consisting of hydrocarbon compounds, fatty acid compounds, alcohol compounds, and ester compounds,

preferably, the inorganic precursor contains at least one selected from the group consisting of silicon alkoxide, titanium alkoxide, tin alkoxide, zirconium alkoxide, aluminum alkoxide, and boric acid,

preferably, the mass ratio of the inorganic substance precursor to the phase change material is 0.1: 100-50: 100, and preferably 0.5: 100-25: 100.

9. The method according to claim 8, wherein the inorganic precursor comprises at least one selected from the group consisting of methyl orthosilicate, ethyl orthosilicate, epoxypropyltrimethoxysilane, phenyltriethoxysilane, aminopropyltrimethoxysilane, phenyltrimethoxysilane, n-octyltriethoxysilane, tetra-n-butyl titanate, tetraisopropyl titanate, tetrabutyl stannate, tetrabutyl zirconate, triisopropyl aluminate, tribenzyl aluminate, and boric acid.

10. The production method according to claim 7, wherein in the step (b), the concentration of the Janus particles is 0.05 to 5%,

preferably, the Janus particles comprise inorgano-polymeric Janus particles, polymer-polymeric Janus particles, or inorgano-inorgano Janus particles.

11. The production method according to claim 7, wherein in the step (c), the volume ratio of the dispersed phase to the continuous phase is 1:1 to 1:100, preferably 1:1 to 1:50,

preferably, the Pickering emulsion is formed by high-speed shear emulsification or ultrasonic emulsification,

preferably, the shearing speed of the high-speed shearing emulsification is 1000-25000 rpm, the shearing time is 0.5-30 min,

preferably, the ultrasonic frequency during ultrasonic emulsification is 1000-40000 Hz, and the ultrasonic emulsification time is 10-60 min.

12. The process according to claim 7, wherein in the step (d), the reaction temperature of the sol-gel reaction at the water-oil interface is 23 to 100 ℃ and the reaction time is 0.5 to 72 hours.

13. The manufacturing method according to claim 7, further comprising:

(e) and (d) a post-treatment step of separating, washing and drying the phase-change microcapsules obtained in the step (d).

14. The application of the inorganic shell layer-based phase change microcapsule according to any one of claims 1 to 7 to textile materials, building energy-saving materials, materials in the fields of electronic component thermal management and waste heat recovery, space thermal protection materials, weapon equipment warehouse wall temperature control materials or wearable equipment materials in the military field.

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