CN1321734C - Synthesizing inorganic microcapsules of storing energy through phase change by using method of solution precipitation polymerization - Google Patents

Abstract

The invention is a technique for synthesizing inorganic phase change energy storage microcapsules by adopting a polymer solution precipitation polymerization method. The phase change core material of the present invention mainly uses inorganic hydrates with a phase transition temperature of 10-90°C, uses vinyl and bisvinyl free radical monomers as the source of shell polymers, and uses hydrocarbons, alcohols, ketones, ethers, The ester organic solvent is used as the polymerization medium, the non-ionic surfactant is used as the dispersion protection agent of the phase change substance, and the peroxide or azo compound is used as the initiator, and the inorganic compound is obtained by precipitating and polymerizing at a temperature of 20-100°C. Phase change microcapsules. The microcapsule is especially suitable for mixing, compounding, coating and pouring of flexible textile materials.

Description

Synthesis of Inorganic Phase Change Energy Storage Microcapsules by Solution Precipitation Polymerization

Technical field:

The invention relates to a technique for synthesizing inorganic phase change energy storage microcapsules by adopting a polymer solution precipitation polymerization method.

Background technique:

Phase-change energy storage materials are smart materials that improve energy utilization and can self-adaptively release and store heat, and have shown application prospects in environmental temperature control (Chen Aiying, Jiang Xueying, Cao Xuezeng. Research progress and application of phase change energy storage materials . Materials Bulletin. 2003, 17(5): 42-44). Using phase-change energy storage materials to make building interior decoration materials can make full use of environmental energy and obtain the effect of warming in winter and cooling in summer (Liang Caihang and Huang Xiang, Application of phase-change materials in buildings. Building Thermal Ventilation and Air Conditioning. 2004, 23(4) :23-26). Used in the interior decoration of space stations and manned spacecraft, it can not only reduce the temperature fluctuation in the cabin and obtain a comfortable space environment, but also effectively reduce energy dissipation and save energy (Ye Sihua, Guo Yuanqiang, Lu Shehui, Chen Mingcai, microcapsule phase change materials And Its Application, Polymer Materials Science and Engineering. 2004, 20(5): 6-9).

With the increase and diversification of people's requirements for clothing, in addition to the appearance and comfort of clothing, they also hope to have multiple functions, such as far infrared, anti-ultraviolet, negative ions, antibacterial, anti-mite, flame retardant, radiation, etc. Shielding, thermal isolation and other functions. The phase-change energy storage microcapsule is a basic material that can be used as a coating or filler for clothing materials, and can be used to adaptively adjust the temperature of the human body environment. Zhang Xingxiang. Research and Application of Phase Change Material Microcapsules. Materials Herald. 2002, 16(12): 61-64). When wearing this type of clothing containing phase-change energy storage microcapsules and entering a higher-temperature environment from a normal room temperature environment, the phase-change material in the microcapsules will change from solid to liquid due to the temperature and absorb heat, thereby slowing down the energy consumption. An increase in body temperature. Conversely, when entering a lower temperature environment from a normal room temperature environment, the phase change material changes from a liquid state to a solid state and releases heat, thereby slowing down the reduction of the body surface temperature. Thus, the human body is automatically kept comfortable under high and low temperatures.

There are many patent reports on phase change energy storage materials and their application materials. There are nearly 750 patents in the United States alone; there are nearly 150 patents in China. There are also patent reports on phase-change energy storage microcapsule materials and their application materials and technologies. There are nearly 60 patents in the United States; only 6-7 in China. Among them, reports on the preparation technology of phase-change energy storage microcapsules are quite limited at home and abroad. For example, foreign K.K.Mistry et al. use repellent solution to separate the shell as a polymer and the core as a microparticle of a phase change, and prepare a microcapsule method (Mistry K K, Preston J A, Symes K C, Particles, USP-6,753,083.Ciba Specialty Chemicals Water Treatments Ltd., June 22, 2004); M.C.Magill et al processed multi-component phase change fibers with thermal phase change microcapsules as a composite of fibers (Magill M C, Hartmann M H, Haggard J S.Multi-component fibers having enhanced reversible thermal properties and methods of manufacturing thereof, USP-6,855,422.February 15, 2005); D.A.Davis et al. used large capsules to coat microcapsules to form solid-solid phase change materials in a stable form, but only briefly mentioned microcapsules The scale is 2-50 μm and the content can reach 80% (Davis D A, Hart R L, Work D E, et al., Macrocapsules containing microencapsulated phase change materials, USP-6,835,334. Microtek Laboratories, Inc., December 28, 2004); R.C Weston and H.R Dungworth introduced a microcapsule preparation method (Weston R C, Dungworth H R, Particulate compositions and their manufacture, USP- 6,716,526.Ciba Specialty Chemicals Water Treatments Ltd., April 6, 2004); D.P.Colvin and others only described the hard and epoxy materials that can prepare phase-change microcapsule materials with a diameter of 1-100 μm and are used for endothermic and exothermic occasions. In resins (Colvin D P, Bryant Y G, Mulligan J C, Method of using thermal energy absorbing and conducting potting materials, USP-5,224,356. Triangle Research & Development Corp., July 6, 1993); Chen and Eichelberger introduced the size in 1/8-1 inch microcapsules containing phase-change materials and their preparation method for mechanical separation (Chen J CH, Eichelberger J L, Encapsulated phase change thermal energy storage materials and process, USP-4,513,053. Pennwalt Corporation, April 23, 1985). For example, "a microcapsule-coated phase-change material and its preparation method (patent application number: 03130587.3, publication date: 2004.07.21)" by Wang Lixin et al. is a technique for coating phase-change materials with polymers by emulsification. "Automatic temperature-regulating fiber and its products (Chinese patent-ZL00105837.1, date of authorization announcement: March 19, 2003)" by Zhang Xingxiang and others is a capsule wall synthesized by in-situ polymerization, and the phase change material is capsule Core microcapsules, for preparing temperature-regulating fibers; Y.G. Bryant et al. "A heat-insulating coating and method using microencapsulated phase-change materials (Chinese patent-ZL98804081.6, publication date: 2000.05.03)" , is a coating-based method, not a preparation method of microcapsule phase change materials. Obviously, there is no similar or similar patent report on the method of synthesizing inorganic phase change energy storage microcapsules by polymer solution precipitation polymerization.

The invention is a method for synthesizing inorganic phase change energy storage microcapsules by adopting a polymer solution precipitation polymerization method.

The phase change energy storage material prepared by the microcapsule method has the characteristics and performance of solid-solid phase change in shape. Generally, solid-solid phase change energy storage materials at medium and low temperatures, because the end groups at one or both ends of the molecular chain are fixed, the phase change temperature will change, and the heat per unit mass of the phase change is higher than that of solid-liquid phase change materials. to be low. Although the solid-liquid phase change material has a large phase change energy, it is prone to leakage of the material and failure of the overall mechanical properties in the liquid state, especially for the application of flexible textile materials.

Using microcapsule technology to fix medium and low temperature phase change materials inside the microcapsules, the phase change materials are still free, and their phase change temperature and phase change calorific value will not change. It can not only maintain the appearance of the material, but also have a large phase change energy. The invention uses inorganic compounds as phase-change energy storage materials, and adopts the technology of polymer solution precipitation polymerization to synthesize microcapsules. Inorganic phase change materials have the characteristic of higher thermal efficiency than organic phase change materials.

Solution precipitation polymerization technology is a polymer synthesis technology in which the polymer is insoluble in a solvent, but the monomer can be dissolved in the solvent. The invention utilizes the polymer synthesis technology to prepare phase change microcapsules. The technical key of the present invention is that there is a solvent capable of dissolving the monomers used for synthesizing polymers but not dissolving the synthesized polymers and the encapsulated phase-change materials.

Invention content:

The purpose of the present invention is to relate to a kind of technology that adopts the method for polymer solution precipitation polymerization to synthesize inorganic phase change energy storage microcapsules.

The use of inorganic phase change materials has higher thermal efficiency than organic phase change materials; the preparation of microcapsules by polymer solution precipitation polymerization can use a variety of radical polymerized vinyl monomers, and the source of monomers is wide; special functional units can also be used body. The size of the microcapsules can be adjusted arbitrarily.

Main technique of the present invention can be expressed as follows:

Disperse the inorganic phase change core material at the required phase transition temperature in an organic solvent dissolved in a surfactant at a temperature above its phase transition temperature, add a metered monomer containing an initiator, and polymerize at a certain temperature, The polymer is deposited on the surface of the small particle or droplet of the inorganic phase change material to obtain the phase change microcapsule with the required phase change temperature.

It is characterized by using inorganic hydrate with a phase transition temperature of 10-90°C as the source of the phase change material, together with anti-supercooling agent and anti-phase separation agent to form a phase change core material; vinyl and divinyl free radicals Body is the source of shell polymer; hydrocarbon, alcohol, ketone, ether, ester organic solvent is used as polymerization medium; non-ionic surfactant is used as dispersion protection agent of phase change substance; peroxide or azo compound is used as initiator , at a temperature of 10-100 ° C to carry out precipitation polymerization encapsulation to obtain phase change microcapsules. This polymerization is a free radical polymerization, and a high activation energy initiator is used at a high temperature, and a low activation energy initiator is used at a low temperature, so the polymerization time is basically the same, between 4-8 hours.

The phase change core material is composed of inorganic hydrate, anti-overcooling agent and anti-phase separation agent.

The inorganic hydrate is sodium sulfate hydrate, potassium sulfate hydrate, ammonium sulfate hydrate, sodium bisulfate hydrate, sodium acetate hydrate, potassium acetate hydrate, ammonium acetate hydrate, calcium chloride hydrate, sodium carbonate hydrate, potassium carbonate hydrate, Ammonium carbonate, hydrated ammonium bicarbonate, hydrated disodium hydrogen phosphate, hydrated dipotassium hydrogen phosphate, hydrated diammonium hydrogen phosphate, hydrated sodium dihydrogen phosphate, hydrated potassium dihydrogen phosphate, hydrated ammonium dihydrogen phosphate, hydrated sodium phosphate, hydrated phosphoric acid Potassium, hydrated ammonium phosphate, hydrated sodium nitrate, hydrated potassium nitrate, hydrated ammonium nitrate, and mixtures of the foregoing hydrates.

The anti-supercooling agent is borax, zinc acetate, lead acetate, lithium titanium hexafluoride, barium sulfide, calcium phosphate hydrate, sodium metaphosphate hydrate, calcium hydrogen phosphate, calcium sulfate, calcium acetate, calcium hydroxide, calcium carbonate or graphite.

Described anti-phase separation agent is superabsorbent resin, sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium stearate, ammonium stearate, potassium stearate, polyethylene glycol, polyethylene alcohol, ammonium polyacrylamide, polyvinylpyrrolidone, sodium polyacrylate, gelatin, carboxymethylcellulose, silica, bentonite or attapulgite.

The above three substances together constitute the phase change core material, wherein the weight percentage of the inorganic hydrate, anti-supercooling agent and anti-phase separation agent is 90-99:0.5-6:0.5-4.

The organic solvent is C _6-40 straight chain or branched alkanes, C _1-6 fatty alcohols, benzene, toluene, xylene, petroleum ether, acetone, butanone, ethyl acetate, butyl acetate or acetic acid Amyl esters.

The monomer is styrene, methylstyrene, vinyl acetate, acrylonitrile, methyl methacrylate, ethyl methacrylate, divinylbenzene, ethylene glycol dimethacrylate or terephthalate Diallyl formate can be one or a mixture of several monomers.

The dispersion protection agent is a variety of nonionic surfactants with molecular formula R(OCH ₂ CH ₂ ) _n OH, wherein R is C _8-18 alkylphenol, alkyl and acyl alkyl, and n is 3- 20, and the nonionic surfactants of Siben series and Tween series, which can be used alone or in combination.

Described initiator is benzoyl peroxide, lauryl peroxide, tert-butyl peroxypivalate, diisopropyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, azobisisobutyl Nitrile or azobisisoheptanonitrile.

The dispersion temperature of the inorganic phase change material in the polymerization medium is 20-100°C.

The said polymerization coating temperature is 10-100°C.

The average size of the obtained phase-change energy storage microcapsules can be adjusted arbitrarily between 0.2-10 μm, as shown in Fig. 1 . It is especially suitable for mixing, compounding, coating and pouring of flexible textile materials.

The weight ratio of the core material, vinyl monomer, dispersion protection agent and initiator is 10～30:10～20:0.05～0.5:0.01～0.3, and the weight ratio of core material and organic solvent is 10～30: 50~90.

Description of drawings:

Figure 1 is a transmission electron microscope image of phase change microcapsules

Detailed ways:

The following examples will help to understand the present invention, but do not limit the content of the present invention.

Example 1

Disperse the inorganic phase change core material at the required phase transition temperature in an organic solvent dissolved in a surfactant at a temperature above its phase transition temperature, add a metered monomer containing an initiator, and polymerize at a certain temperature, The polymer is deposited on the surface of the small particle or droplet of the inorganic phase change material to obtain the phase change microcapsule with the required phase change temperature. The specific phase change core material formula, polymer wrapping formula, process and results are shown in the table below.

1. Phase change core material formula

plan  Inorganic phase change material concentration%   Anti-supercooling agent concentration%  Concentration of anti-phase separation agent% 1   Sodium Sulfate Decahydrate 95 Borax 3   Macrogol 2 2   Sodium acetate trihydrate 96.5   Zinc acetate 2 Gelatin 1.5 3  Calcium chloride hexahydrate 95.7   Calcium Hydroxide 3.5  Carboxymethylcellulose 0.8 4   Disodium hydrogen phosphate dodecahydrate 95.9 Graphite 0.9 Sodium dodecylbenzenesulfonate 3.2 5   Magnesium Sulfate Hexahydrate 95.4   Calcium sulfate 0.6   Polyvinyl alcohol 4 6   Dipotassium hydrogen phosphate hexahydrate 96.5 Calcium carbonate 1   Polyacrylamide 2.5

2. Polymerized package formula:

plan Phase change core material concentration% Concentration of organic solvent%   Dispersion protective agent concentration % Monomer Concentration % Initiator Concentration % 1 14 7# white oil 72.9   OP-3+OP-100.06+0.01 Acrylonitrile + divinylbenzene 10 + 3 Azobisisobutyronitrile 0.03 2 twenty two Ethyl acetate 61.68 JFC+OP-40.02+0.25 Methyl methacrylate+ethylene glycol dimethacrylate 15+1 Diisopropyl peroxydicarbonate 0.05 3 12 Butanol 77.75   MOA-3+MOA-80.16+0.02 Methyl styrene 10 Azobisisoheptanonitrile 0.07 4 16 Kerosene 70.61 MOA-60.25 Styrene 13 Benzoyl peroxide 0.14 5 12 Xylene 71.7 AEO-9+MOA-30.02+0.2 Methyl methacrylate 16 Lauryl peroxide 0.08 6 20 Petroleum ether 65.64 T80+S400.03+0.27 Styrene + divinylbenzene 12 + 2 Benzoyl peroxide 0.06

The raw materials used in the formula are commercially available products, and the names of the surfactants are all the trade names of the surfactants described above.

3. Process and result:

plan   Dissolution and dispersion temperature (°C)   Polymerization coating temperature (°C) Aggregation time (hour)   Phase transition temperature (°C)   Average particle size μm 1 35 80 4-6 32 0.35 2 62 40 5-6 58 0.6 3 33 30 4-6 29 1.8 4 38 75 5-7 35 0.75 5 71 35 4-7 67 0.8 6 52 80 4-6 48 0.5

Example 2

Take 15-16 grams of calcium chloride hexahydrate, 0.1-0.2 grams of calcium hydroxide, and 0.5-0.7 grams of carboxymethyl cellulose for mixing. At a temperature of 40°C, disperse in 70-75 grams of butanone dissolved with 0.06 grams of OP-3 and 0.01 grams of OP-10, and then add monomers containing 0.02-0.07 grams of azobisisoheptanonitrile (styrene 10 -14 grams and 1-3 grams of divinylbenzene), control the temperature at 35°C to carry out polymerization, so that the polymer is deposited on the surface of the small particles or droplets of the inorganic phase change material, and the phase change microcapsules with a phase change temperature of 29°C are obtained. .

The above polymerization product was distilled off under reduced pressure to remove butanone. The dry powdery substance obtained is pure phase-change microcapsules. Disperse 40 grams of the above-mentioned microcapsules in 60 grams of 2D resin, then put the cotton knitted fabric into the above-mentioned resin liquid, after padding, bake to obtain the knitted fabric containing the phase change material.

The phase change temperature of the coated phase change knitted fabric is 31-34° C., the weight gain rate relative to the original fabric is 11.8%, and the phase change energy of the coated fabric is about 4.6 joules/gram. The weight gain rate after 10 standard washings was 10.9%; the phase transition energy was 4.1 J/g. It shows that the temperature regulation of phase change after coating treatment of phase change microcapsule material is obvious.

Example 3

Taking the phase-change core material formulation, polymeric encapsulation formulation and microcapsule forming preparation process of Scheme 6 in Example 1, phase-change microcapsules with a phase transition temperature of 48°C were obtained.

The above polymerization product was distilled off under reduced pressure to remove petroleum ether. The dry powdery substance obtained is pure phase-change microcapsules. Disperse 40 grams of the above-mentioned microcapsules in 1000 grams of 15% polyvinyl alcohol aqueous solution, and spin them with a wet spinning process to obtain vinylon composite fibers containing phase change materials. The fiber can be spun into a variety of temperature-adjusted fabrics with a phase transition temperature of 48°C.

Claims (6)

1. A method for synthesizing inorganic phase-change energy storage microcapsules by polymer solution precipitation polymerization, characterized in that inorganic hydrates with a phase-change temperature of 10-90°C are used as the source of phase-change materials and anti-supercooling agents and anti-overcooling agents. The phase separation agent together constitutes the phase change core material; vinyl and bisvinyl free radical monomers are used as the shell polymer source; hydrocarbons, alcohols, ketones, ethers or ester organic solvents are used as the polymerization medium; nonionic surface active The agent is the dispersion protection agent of the phase change substance; the phase change microcapsules are obtained by precipitating polymerization coating with peroxide or azo compound as the initiator; The polymer coating is at a temperature above the phase transition temperature of the inorganic phase change core material, and the inorganic phase change core material with a phase transition temperature of 10-90°C is dispersed in an organic solvent dissolved in a surfactant to form an inorganic phase change core material. Phase-change core material droplets, and then adjusted to a polymerization temperature of 10-100°C, adding monomers containing initiators for polymerization, so that the polymer is deposited on the surface of the inorganic phase-change core material to form microcapsules; the inorganic phase-change The temperature at which the core material is dispersed in an organic solvent is 20-100°C; Wherein the weight ratio of inorganic hydrate, anti-supercooling agent and anti-phase separation agent is 90～99:0.5～6.0:0.5～4, and the weight ratio of core material, monomer, dispersion protection agent and initiator is 10～30: 10～20:0.05～0.5:0.01～0.3, the weight ratio of core material and organic solvent is 10～30:50～90; The monomer is styrene, methylstyrene, vinyl acetate, acrylonitrile, methyl methacrylate, ethyl methacrylate, divinylbenzene, ethylene glycol dimethacrylate or terephthalate A mixture of one or several monomers in diallyl formate; the organic solvent is straight-chain or branched alkanes with carbon numbers of C _6-40 , fatty alcohols with C _1-6 , benzene, toluene, di Toluene, petroleum ether, acetone, methyl ethyl ketone, ethyl acetate, butyl acetate or pentyl acetate; The initiator is benzoyl peroxide, lauryl peroxide, tert-butyl peroxypivalate, peroxide Oxidized diisopropyl dicarbonate, dicyclohexyl peroxydicarbonate, azobisisobutyronitrile or azobisisoheptanonitrile; the inorganic hydrates are sodium sulfate hydrate, potassium sulfate hydrate, ammonium sulfate hydrate, Sodium bisulfate hydrate, Sodium acetate hydrate, Potassium acetate hydrate, Ammonium acetate hydrate, Calcium chloride hydrate, Sodium carbonate hydrate, Potassium carbonate hydrate, Ammonium carbonate hydrate, Ammonium bicarbonate hydrate, Disodium hydrogen phosphate hydrate, Dipotassium hydrogen phosphate hydrate , diammonium hydrogen phosphate hydrate, sodium dihydrogen phosphate hydrate, potassium dihydrogen phosphate hydrate, ammonium dihydrogen phosphate hydrate, sodium phosphate hydrate, potassium phosphate hydrate, ammonium phosphate hydrate, sodium nitrate hydrate, potassium nitrate hydrate or ammonium nitrate hydrate A mixture of one or more hydrates. 2. The method according to claim 1, characterized in that the anti-supercooling agent is borax, zinc acetate, lead acetate, lithium titanium hexafluoride, barium sulfide, calcium phosphate hydrate, sodium metaphosphate hydrate, calcium hydrogen phosphate , calcium sulfate, calcium acetate, calcium hydroxide, calcium carbonate or graphite. 3. The method according to claim 1, characterized in that the anti-phase separation agent is superabsorbent resin, sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium stearate, stearic acid Ammonium, potassium stearate, polyethylene glycol, polyvinyl alcohol, polyacrylamide, polyvinylpyrrolidone, sodium polyacrylate, gelatin, carboxymethylcellulose, silicon dioxide, bentonite, or attapulgite. 4. The method according to claim 1, characterized in that the dispersion protection agent is a variety of non-ionic surfactants with the molecular formula R(OCH ₂ CH ₂ ) _n OH, wherein R is a C _8-18 alkane phenol, alkyl or acyl alkyl, n is 3-20, and nonionic surfactants of Spen series or Tween series, used alone or in combination. 5. The method according to claim 1, characterized in that said microcapsules have a diameter of 0.2-10 μm. 6. The method according to claim 1, characterized in that the microcapsules prepared by the method are suitable for mixing, compounding, coating and pouring of flexible textile materials.

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