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CN-122006610-A - Phase-change microcapsule material based on polyolefin shell structure

CN122006610ACN 122006610 ACN122006610 ACN 122006610ACN-122006610-A

Abstract

The invention provides a phase change microcapsule material based on a polyolefin shell structure, which is characterized in that an olefin wall material monomer, a phase change material core material, an emulsifier, an anionic auxiliary emulsifier, a cross-linking agent and an initiator are dispersed in deionized water, an oil-in-water microemulsion is obtained through emulsification, the oil-in-water microemulsion is added into a chitosan solution, ionic micelle reaction is carried out at 40-60 ℃ and 100-1000 r/min to obtain microcapsule precursor suspension with a chitosan micelle template shell, the microcapsule precursor suspension is subjected to polyolefin shell polymerization reaction at the stirring rate of 65-85 ℃ and 100-600 r/min to obtain microcapsule suspension, and the microcapsule suspension is centrifuged at 1000-8000 rpm to obtain the phase change microcapsule material based on the polyolefin shell structure.

Inventors

  • ZHANG GUOLIANG
  • ZHANG QIANZHE
  • XU ZEHAI

Assignees

  • 浙江工业大学

Dates

Publication Date
20260512
Application Date
20260325

Claims (10)

  1. 1. The phase-change microcapsule material based on the polyolefin shell structure is characterized by being prepared by the following steps: (1) Dispersing an olefin wall material monomer, a phase change material core material, an emulsifying agent, an anionic co-emulsifying agent, a cross-linking agent and an initiator in deionized water for 10-30 min at the stirring speed of 40-60 ℃ and 600-6000 r/min to obtain an oil-in-water microemulsion, wherein the olefin wall material monomer is one or more of acrylic acid and derivatives thereof, acrylonitrile and derivatives thereof or styrene, the phase change material core material is one or more of linear alkane, fatty alcohol or fatty acid, the emulsifying agent is one or more of nonionic surfactants, the anionic co-emulsifying agent is one or more of fatty acid salt, polyol carboxylate salt, phosphate salt or alkyl benzene sulfonate, the initiator is one or more of organic peroxide, azo compound or persulfate, the mass ratio of the total mass of the olefin wall material monomer to the phase change material core material is 0.5-1.5:1, the mass ratio of the total mass of the olefin wall material monomer to the phase change material core material is one or more of linear alkane, the fatty alcohol or fatty acid, the mass ratio of the anionic co-emulsifying agent to the phase change material core material is one or more of 1-1.1:1, the mass ratio of the anionic co-emulsifying agent to the total mass of the olefin material monomer to the phase change material is 1:1:1; (2) Dissolving chitosan in an organic acid aqueous solution with the mass fraction of 0.5-2% to obtain a chitosan solution, wherein the mass fraction of chitosan in the chitosan solution is 1-10%, and the organic acid in the organic acid aqueous solution is formic acid, acetic acid, oxalic acid or citric acid; (3) Adding the oil-in-water microemulsion of the step (1) into the chitosan solution of the step (2), and carrying out ionic micelle reaction for 10-30 min at the stirring speed of 100-1000 r/min at the temperature of 40-60 ℃ to obtain microcapsule precursor suspension with a chitosan micelle template shell, wherein the volume ratio of the oil-in-water microemulsion to the chitosan solution is 1-3:1; (4) Carrying out polyolefin shell polymerization reaction on the microcapsule precursor suspension obtained in the step (3) for 2-10 hours at the stirring speed of 100-600 r/min at the temperature of 65-85 ℃ to obtain microcapsule suspension; (5) Centrifuging the microcapsule suspension in the step (4) at 1000-8000 rpm for 1-10 min to obtain a microcapsule cake cover suspended at the top of the centrifugate, taking out the microcapsule cake cover, respectively washing the microcapsule cake cover with deionized water and absolute ethyl alcohol, and then drying the microcapsule cake cover at 30-60 ℃ for 2-5 h to obtain the phase-change microcapsule material based on the polyolefin shell structure.
  2. 2. The phase change microcapsule material based on a polyolefin shell structure according to claim 1, wherein the phase change material core material in the step (1) is a linear alkane, and the linear alkane is one or more of n-tetradecane, n-hexadecane and n-octadecane.
  3. 3. The phase change microcapsule material based on a polyolefin shell structure according to claim 1, wherein the olefin wall material monomer in the step (1) is one or more of methyl methacrylate, methacrylic acid, butyl acrylate, acrylonitrile or styrene.
  4. 4. The phase change microcapsule material based on a polyolefin shell structure according to claim 1, wherein the emulsifier in step (1) is one or more of tween-80, tween-20, polyvinyl alcohol-0588 or span-20.
  5. 5. The phase change microcapsule material based on a polyolefin shell structure according to claim 1, wherein the anionic co-emulsifier in the step (1) is alkylbenzene sulfonate, and the alkylbenzene sulfonate is one or more of sodium dodecylbenzene sulfonate, sodium dodecylsulfonate or sodium alpha-alkenyl sulfonate.
  6. 6. The phase change microcapsule material based on a polyolefin shell structure according to claim 1, wherein the crosslinking agent in step (1) is one or more of divinylbenzene, diallyl phthalate, pentaerythritol acrylate or ethylene glycol diacrylate.
  7. 7. The phase change microcapsule material based on a polyolefin shell structure according to claim 1, wherein the initiator in the step (1) is one or more of azobisisobutyronitrile, dimethyl azobisisobutyrate, dibenzoyl peroxide, potassium persulfate or ammonium persulfate.
  8. 8. The phase-change microcapsule material based on a polyolefin shell structure according to claim 1, wherein the volume of deionized water in the step (1) is 10-30 ml/g based on the mass of the phase-change material core material.
  9. 9. The phase-change microcapsule material based on a polyolefin shell structure as claimed in claim 1, wherein the microcapsule suspension in the step (4) is further treated by adding an acidic substance into the microcapsule suspension in the step (4) to adjust the pH to 2-4, reacting at a stirring rate of 40-60 ℃ and 100-1000 r/min for 10-60 min to obtain a suspension of shell microcapsules with the outer-layer ion micelle shell removed, centrifuging the shell microcapsule suspension at 1000-8000 rpm for 1-10 min to obtain a shell microcapsule cake cover suspended on top of the centrifugate, taking out the shell microcapsule cake cover, washing with deionized water and absolute ethyl alcohol respectively, and then drying at a temperature of 30-60 ℃ for 2-5 h to obtain the phase-change microcapsule based on the polyolefin shell structure.
  10. 10. The phase-change microcapsule material based on a polyolefin shell structure according to claim 1, which is prepared by the following method: (1) Dispersing an olefin wall material monomer, a phase change material core material, an emulsifying agent, an anionic auxiliary emulsifying agent, a cross-linking agent and an initiator in deionized water, emulsifying for 10-30 min at a stirring rate of 40-60 ℃ and 600-6000 r/min to obtain an oil-in-water microemulsion, wherein the olefin wall material monomer is methyl methacrylate, the phase change material core material is n-octadecane, the emulsifying agent is one or more of nonionic surfactants, the anionic auxiliary emulsifying agent is sodium dodecyl benzene sulfonate, the initiator is azobisisobutyronitrile, the cross-linking agent is pentaerythritol acrylic ester, the mass ratio of the olefin wall material monomer to the phase change material core material is 0.5-1.5:1, the mass ratio of the olefin wall material monomer to the cross-linking agent is 2-4:1, the mass ratio of the emulsifying agent to the anionic auxiliary emulsifying agent to the phase change material core material is 0.1-1:1, the mass ratio of the emulsifying agent to the anionic auxiliary emulsifying agent to the phase change material core material is 30-1:1, and the mass ratio of the cross-linking agent to the phase change material is 150-50 ml of deionized water based on the total volume of the core material; (2) Dissolving chitosan in an organic acid aqueous solution with the mass fraction of 0.5-2% to obtain a chitosan solution, wherein the mass fraction of chitosan in the chitosan solution is 1-10%, and the organic acid in the organic acid aqueous solution is formic acid, acetic acid, oxalic acid or citric acid; (3) Adding the oil-in-water microemulsion of the step (1) into the chitosan solution of the step (2), and carrying out ionic micelle reaction for 10-30 min at the stirring speed of 100-1000 r/min at the temperature of 40-60 ℃ to obtain microcapsule precursor suspension with a chitosan micelle template shell, wherein the volume ratio of the oil-in-water microemulsion to the chitosan solution is 1-3:1; (4) Carrying out polyolefin shell polymerization reaction on the microcapsule precursor suspension obtained in the step (3) for 2-10 hours at the stirring speed of 100-600 r/min at the temperature of 65-85 ℃ to obtain microcapsule suspension; (5) Centrifuging the microcapsule suspension in the step (4) at 1000-8000 rpm for 1-10 min to obtain a microcapsule cake cover suspended at the top of the centrifugate, taking out the microcapsule cake cover, respectively washing the microcapsule cake cover with deionized water and absolute ethyl alcohol, and then drying the microcapsule cake cover at 30-60 ℃ for 2-5 h to obtain the phase-change microcapsule material based on the polyolefin shell structure.

Description

Phase-change microcapsule material based on polyolefin shell structure Technical Field The invention belongs to the technical field of phase change material coating, relates to a phase change microcapsule prepared by a phase change material coating technology, and particularly relates to a phase change microcapsule material based on a polyolefin shell structure, which is prepared by a microemulsion process and has high yield and high heat storage performance. Background The wall materials of the phase change microcapsule products for realizing industrialized application at the present stage are mainly divided into amine aldehyde resins (such as formaldehyde resin, urea resin and the like) and polyolefin (such as polymethyl methacrylate and the like). On one hand, the lack of hardness of the amine aldehyde resin microcapsules leads to poor microscopic morphology and overall mechanical properties of microcapsule products, and on the other hand, toxic substances such as formaldehyde are released in the preparation and use processes of the amine aldehyde resin microcapsules, so that the safety and environmental friendliness of the products are reduced. The preparation process of the polyolefin microcapsule does not involve formaldehyde, and the product has excellent mechanical property and chemical stability, thus becoming a main direction of the research and development work of the phase-change microcapsule at present. In the conventional process for producing polyolefin microcapsules by the microemulsion method, the dispersed phase (oil drop) needs to contain a high concentration of wall material monomer (a low core-shell ratio, generally ranging from 1:1 to 2) to maintain the strength of the crosslinking reaction, so that a part of wall material monomer finally forms a compact shell, and the rest of wall material monomer generally generates plastic particles to become byproducts. However, a lower core-shell ratio results in lower conversion of the raw materials and lower yield of microcapsules (30-50%, mainly waste of wall material). At present, the effect of preparing the microcapsules with high yield (more than or equal to 90 percent) can be achieved only by tip technologies such as micro-flow control, rapid solvent volatilization and the like, but the technologies are still in a laboratory development stage, and strict parameter control and expensive equipment investment are required. In the process of preparing the phase-change microcapsule by the microemulsion method, the reason that the high core-shell ratio cannot be adopted is mainly that the olefin polymerization reaction belongs to a carbon-carbon double bond crosslinking reaction initiated by free radicals, and the first-order reaction kinetics rule is followed. Therefore, the polymerization rate and the crosslinking degree are low due to the insufficient concentration of the wall material monomer, so that the shell formed in the early stage is very weak and unstable, the phenomena of cracking, falling off and the like easily occur in the dynamic environment of the microemulsion, the core-shell structure of the early stage microcapsule cannot be maintained to a stage of compact shell formation, and finally, the microcapsule structure is easy to disintegrate in the reaction process to form byproduct fragments. Although the formation of dense shells can be accelerated by the schemes of increasing the temperature, the amount of initiator and cross-linking agent, and reducing the stirring rate, and the physical impact on the early microcapsules can be reduced, the problem that the shells of the microcapsules are easy to break is relieved. However, too severe reaction environment and polymerization process can cause problems of rough shell surface, hole generation, adhesion of microcapsules, etc., and the fragile shell structure formed at early stage cannot be effectively protected all the time, and the cost of energy and reagents can be remarkably increased, so that the method cannot be regarded as a better solution. In summary, how to cover a dense protective shell on the surface of the oil phase droplet before the synthesis reaction of the microcapsule, and to perform closed protection for the early-formed microcapsule core-shell structure during the reaction is a key point for solving the problem of low yield of the thin-wall microcapsule. The ionic micelle reaction has been widely paid attention as a novel method for designing a supermolecular material. Chitosan is the only electropositive aminopolysaccharide in nature, and is the first choice material for ionic micelle technology. The protonized chitosan can be reacted with a plurality of anionic high molecular substances through ionic micelle to quickly obtain supermolecular structures such as nanofibers, nanoparticles and the like, and the chitosan-based ion-exchange beam supermolecular material is widely applied to the preparation of novel film materials, gel materials, fiber nano materials an