Hydrogel composite coating and hydrogel composite coating for heat dissipation
By developing hydrogel composite coatings, using hydrogel microcapsules with core-shell structures, the problem that existing hydrogel materials cannot be directly combined with coating resins is solved, and efficient heat dissipation effect suitable for outdoor coating processes is achieved.
Patent Information
- Application Number
- CN202411673422.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-21
- Publication Date
- 2025-02-25
AI Technical Summary
The existing hydrogel materials cannot be directly combined with coating resins and are not suitable for outdoor coating processes, resulting in high production complexity and cost.
A hydrogel composite coating was developed, including hydrogel microcapsules with aqueous resin and core-shell structure. The shell layer consists of surfactant, epoxy resin, melamine resin, etc. The hydrogel microcapsules were prepared through a specific process so that they could be mixed uniformly with the aqueous resin.
The independent dispersion of hydrogel microcapsules is achieved, which significantly improves the surface area of heat dissipation or return water, enhances mechanical properties and dispersion, is suitable for outdoor coating processes, and achieves long-term and repeated cooling effect through moisture evaporation or absorption.
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of heat dissipation coatings, and in particular to a hydrogel composite coating and a hydrogel composite coating for heat dissipation. Background Art
[0002] Hydrogel is a polymer material rich in water and with a three-dimensional network structure. It exhibits good structural designability, mechanical flexibility and water retention. Hydrogel materials exhibit good cooling and heat dissipation capabilities through water evaporation, and are increasingly widely used in consumer electronic devices, battery thermal management systems, photovoltaics and energy storage. However, existing hydrogel materials often exhibit weak mechanical properties, weak interfacial bonding with plastic or ceramic materials, and have a certain corrosive effect on metals. Therefore, in actual use, multiple materials need to be stacked and packaged to prepare heat dissipation components, which increases the complexity of the production process of heat dissipation components and increases the production cost of heat dissipation components. Most of the existing hydrogel materials used for heat dissipation are prepared through the process of casting, potting and molding to prepare the heat dissipation layer in the form of sheets and tubes. They cannot be directly compounded with coating resins and are not suitable for outdoor coating processes. Therefore, it is expected to develop a material that can be used in outdoor coating processes and can be directly compounded with coating resins to prepare heat dissipation coatings. Summary of the invention
[0003] In view of the technical problem that the existing hydrogel materials cannot be directly compounded with coating resins and are not suitable for outdoor coating processes, the present invention provides a hydrogel composite coating and a hydrogel composite coating for heat dissipation.
[0004] On the one hand, the present invention provides a hydrogel composite coating, including a water-based resin and a hydrogel microcapsule, wherein the hydrogel microcapsule is a core-shell structure, including a core layer and a shell layer, the core layer is a hydrogel particle, and the shell layer includes one or more of a surfactant, an epoxy resin, a melamine resin, and a water-based polyurethane.
[0005] Preferably, the raw materials for preparing the hydrogel microcapsules include the following components: 50-70 parts of organic solvent, 1-4 parts of shell material, 5-10 parts of water-soluble monomer, 0.2-0.5 parts of cross-linking agent, 10-15 parts of hygroscopic component, 0.3-1 parts of initiator, 0.1-0.5 parts of catalyst, and 15-20 parts of water. The shell material includes one or more of surfactant, epoxy resin, melamine resin, and water-based polyurethane.
[0006] Preferably, the particle size of the hydrogel microcapsule is 50-150 μm.
[0007] Preferably, the organic solvent comprises petroleum ether and alkanes, and the alkanes comprise C6-C10 cycloalkanes and C5-C16 straight-chain alkanes; The catalyst includes tetramethylethylenediamine; The surfactant includes one or more of Span 80, Tween 60, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, cetyltrimethylammonium bromide, and sodium vegetable oleate; The water-soluble monomer includes one or more of acrylamide, acrylic acid, hydroxyethyl acrylate, sodium alginate, polyvinyl alcohol, carboxymethyl chitosan, and guar gum; The cross-linking agent includes one or more of methylene bisacrylamide and ethylene glycol diacrylate; The hygroscopic component includes one or more of calcium chloride and lithium chloride; The initiator includes one or more of ammonium persulfate, phenylpropionamide peroxide, and 1-hydroxycyclohexyl phenyl ketone.
[0008] Preferably, the method for preparing the hydrogel microcapsules comprises the following steps: Mixing the organic solvent and the shell material to obtain a first mixed solution; Mixing the water-soluble monomer, the cross-linking agent, the initiator, the hygroscopic component and the water to obtain a second mixed solution; The second mixed solution and the first mixed solution are mixed evenly, the catalyst is added to react, and post-processing is performed to obtain the hydrogel microcapsules.
[0009] Preferably, adding a catalyst to react comprises the following steps: reacting while stirring after adding the catalyst, the stirring speed is 300-500rpm / min, the reaction temperature is 30-60°C, and the reaction time is 5-10min.
[0010] Preferably, the post-treatment to obtain the hydrogel microcapsules comprises the following steps: filtering, washing and drying in sequence after the reaction to obtain the hydrogel microcapsules; The washing liquid used for washing includes an alcohol solvent.
[0011] Preferably, the water-based resin includes one or more of epoxy resin, polyurethane resin and silicone resin. The mass ratio of the aqueous resin to the hydrogel microcapsule is (1:10) to (4:6); The solid content of the water-based resin is 20-35%.
[0012] In a second aspect, the present application provides a hydrogel composite coating for heat dissipation, wherein the hydrogel composite coating is obtained by drying the above-mentioned hydrogel composite coating, and the hydrogel microcapsules are arranged in the hydrogel composite coating.
[0013] Preferably, the drying temperature is 60-80°C and the drying time is 15-30 minutes; And / or, the thickness of the hydrogel composite coating is 10 μm to 300 μm.
[0014] The hydrogel composite coating provided by the present application has the following effects: 1) Different from conventional crushed gel particles, the hydrogel microcapsules are independently dispersed and will not absorb water and bond, which significantly increases the surface area of the hydrogel for heat dissipation or water return; 2) The shell layer also improves the mechanical properties and dispersibility of the hydrogel microcapsules, so that the hydrogel microcapsules can be evenly mixed with the water-based resin to prepare the composite coating, which is suitable for outdoor coating processes; 3) The water-based resin in the coating has a high viscosity with the substrate, which improves the adhesion between the coating and the substrate. The hydrogel microcapsules achieve surface heat dissipation and cooling through the evaporation or absorption of water. Different from the conventional radiation heat dissipation or solid-liquid phase change heat dissipation principle, it can achieve a long-term and repeated cooling effect. The water-based resin can also improve the mechanical strength of the coating to meet the use requirements of outdoor coatings. DETAILED DESCRIPTION
[0015] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.
[0016] In order to illustrate the technical solution of the present invention, specific embodiments are provided below for illustration.
[0017] The present application provides a hydrogel composite coating, comprising a water-based resin and a hydrogel microcapsule, wherein the hydrogel microcapsule is a core-shell structure, comprising a core layer and a shell layer, wherein the core layer is a hydrogel particle, and the shell layer comprises one or more of a surfactant, an epoxy resin, and a melamine resin.
[0018] Specifically, the hydrogel microcapsules are of a core-shell structure, the shell layer material includes one or more of a surfactant, an epoxy resin, and a melamine resin, the core layer is a hydrogel particle, the hydrogel particles of this structure are in the inner layer, and the outer layer of the hydrogel particles is a shell layer including a surfactant, an epoxy resin and other materials, which can prevent the hydrogel particles from sticking together, forming an independently dispersed microcapsule structure, improving the dispersibility of the hydrogel microcapsules, and the setting of the shell layer prevents the hydrogel microcapsules from absorbing water and bonding, significantly increasing the surface area of the hydrogel for heat dissipation or water return; at the same time, the shell layer also improves the mechanical properties of the hydrogel microcapsules, so that the hydrogel microcapsules can be evenly mixed with the water-based resin to prepare a composite coating.
[0019] The hydrogel composite coating includes hydrogel microcapsules, which can be used for heat dissipation and cooling. The cooling principle is as follows: as the temperature rises, the water in the hydrogel particles will gradually evaporate, taking away a large amount of heat, thereby playing a good cooling role on the heat source of the material that needs to be cooled; when the temperature drops, the hydrogel particles will actively absorb and replenish water from the air, and the water in the core layer of the hydrogel microcapsule can be replenished, which can realize the circulation effect of evaporative heat dissipation and low-temperature water return, so that the hydrogel composite coating used for heat dissipation can achieve a long-term and repeated cooling effect.
[0020] The hydrogel composite coating provided by the present application has the following effects: 1) Different from conventional crushed gel particles, the hydrogel microcapsules are independently dispersed microcapsules, which will not absorb water and bond, and significantly increase the surface area of the hydrogel for heat dissipation or water return; 2) The shell layer also improves the mechanical properties and dispersibility of the hydrogel microcapsules, so that the hydrogel microcapsules can be evenly mixed with the water-based resin to prepare the composite coating, which is suitable for outdoor coating processes; 3) The water-based resin in the coating has a high viscosity with the substrate, which improves the adhesion between the coating and the substrate. The hydrogel microcapsules achieve surface heat dissipation and cooling through the evaporation or absorption of water. Different from the conventional radiation heat dissipation or solid-liquid phase change heat dissipation principle, it can achieve a long-term and repeated cooling effect. The water-based resin can also improve the mechanical strength of the coating to meet the use requirements of outdoor coatings.
[0021] In some embodiments, the raw materials for preparing the hydrogel microcapsules include the following components: 50-70 parts of an organic solvent, 1-4 parts of a shell material, 5-10 parts of a water-soluble monomer, 0.2-0.5 parts of a cross-linking agent, 10-15 parts of a hygroscopic component, 0.3-1 parts of an initiator, 0.1-0.5 parts of a catalyst, and 15-20 parts of water. The shell material includes one or more of a surfactant, an epoxy resin, a melamine resin, and an aqueous polyurethane.
[0022] Among them, water is used to dissolve water-soluble monomers, cross-linking agents, hygroscopic components and initiators to obtain an aqueous mixed solution, and an organic solvent is used to dissolve shell materials such as surfactants to obtain an organic mixed solution; the aqueous mixed solution and the organic mixed solution are mixed and reacted to obtain a core-shell structure, in which the core layer is hydrogel particles, and the shell layer is one or more of a surfactant, epoxy resin, melamine resin, and water-based polyurethane.
[0023] Specifically, the amount of organic solvent added can be the following values: 50, 52, 55, 58, 60, 63, 66, 68, 70, etc., as long as the organic solvent is in the range of 50 to 70 parts. The amount of shell material added can be the following values: 1, 1.4, 1.7, 2.0, 2.3, 2.6, 3.0, 3.3, 3.5, 3.8, 4.0, etc., as long as the shell material is in the range of 1 to 4 parts. The amount of water-soluble monomer added can be the following values: 5, 6.0, 6.8, 7.5, 8.0, 8.6, 9.2, 10.0, etc., as long as the water-soluble monomer is in the range of 5 to 10 parts. The amount of cross-linking agent added can be the following values: 0.2, 0.3, 0.4, 0.5, etc., as long as the cross-linking agent is in the range of 0.2 to 0.5 parts. The amount of the hygroscopic component added can be the following values: 10, 10.5, 11, 12, 13, 14, 15, etc., as long as the hygroscopic component is within the range of 10 to 15 parts. The amount of the initiator added can be the following values: 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, etc., as long as the initiator is within the range of 0.3 to 1 part. The amount of the catalyst added can be the following values: 0.1, 0.2, 0.3, 0.4, 0.5, etc., as long as the catalyst is within the range of 0.1 to 0.5 parts. The amount of water added can be the following values: 15, 16, 17, 18, 19, 20, etc., as long as the water is within the range of 15 to 20 parts.
[0024] In some embodiments, the hydrogel microcapsules have a particle size of 50-150 μm.
[0025] Specifically, the particle size of the hydrogel microcapsules is 50-150 μm. The small-sized microcapsules have a larger specific surface area, a larger surface area for heat dissipation or water return, and are conducive to being evenly mixed with the water-based resin to prepare a composite coating. The composite coating is coated on the surface of the substrate, and the small-sized hydrogel microcapsules can be evenly distributed in the coating, which has a better cooling effect on the substrate.
[0026] Specifically, the particle size of the hydrogel microcapsule can be 50 μm, 80 μm, 100 μm, 120 μm, 130 μm, 140 μm, 150 μm, etc., as long as the particle size of the hydrogel microcapsule is within the range of 50-150 μm.
[0027] In some embodiments, the organic solvent includes petroleum ether and alkanes, and the alkanes include C6-C10 cycloalkanes and C5-C16 straight-chain alkanes; The catalyst includes tetramethylethylenediamine; The surfactant includes one or more of Span 80, Tween 60, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, cetyltrimethylammonium bromide, and sodium vegetable oleate; The water-soluble monomer includes one or more of acrylamide, acrylic acid, hydroxyethyl acrylate, sodium alginate, polyvinyl alcohol, carboxymethyl chitosan, and guar gum; The cross-linking agent includes one or more of methylene bisacrylamide and ethylene glycol diacrylate; The hygroscopic component includes one or more of calcium chloride and lithium chloride; The initiator includes one or more of ammonium persulfate, phenylpropionamide peroxide, and 1-hydroxycyclohexyl phenyl ketone.
[0028] Specifically, the organic solvent plays a role in dissolving the surfactant. C6-C10 cycloalkanes include cyclohexane, cycloheptane, cyclononane, etc., and C5-C16 straight-chain alkanes include n-hexane, n-heptane, undecane, tridecane, etc.
[0029] The hygroscopic component includes one or more of calcium chloride and lithium chloride, which helps the hydrogel particles in the hydrogel capsule absorb moisture from the air and store the moisture inside the hydrogel microcapsule, so that the water inside the hydrogel microcapsule can be replenished, and the circulation of evaporative heat dissipation and low-temperature water return can be achieved, so that the hydrogel composite coating used for heat dissipation can achieve a long-term and repeated cooling effect.
[0030] Initiators are used to initiate polymerization reactions of water-soluble monomers and crosslinking agents.
[0031] In some embodiments, the method for preparing the hydrogel microcapsules comprises the following steps: Mixing the organic solvent and the shell material to obtain a first mixed solution; Mixing the water-soluble monomer, the cross-linking agent, the initiator, the hygroscopic component and the water to obtain a second mixed solution; The second mixed solution and the first mixed solution are mixed evenly, the catalyst is added to react, and post-processing is performed to obtain the hydrogel microcapsules.
[0032] The method for preparing hydrogel microcapsules provided in the present application comprises mixing a first mixed solution and a second mixed solution evenly, polymerizing under the action of a catalyst to obtain hydrogel microcapsules having a core layer and a shell layer structure, and the operation process is simple and the cost is low.
[0033] In some embodiments, adding a catalyst to react comprises the following steps: reacting while stirring after adding the catalyst, the stirring speed is 300-500 rpm / min, the reaction temperature is 30-60°C, and the reaction time is 5-10 min.
[0034] Specifically, the stirring speed affects the particle size of the hydrogel microcapsules. By controlling the stirring speed within the range of 300-500rpm / min, and adjusting 1-4 parts of the shell material and 15-20 parts of water at the same time, hydrogel microcapsules with a particle size of 50-150μm can be prepared. Specifically, the stirring speed can be 300rpm / min, 350rpm / min, 400rpm / min, 450rpm / min, 500rpm / min, etc., as long as the stirring speed is within the range of 300-500rpm / min. If the stirring speed is lower than 300rpm / min, the particle size of the generated hydrogel microcapsules is larger, the specific surface area is reduced, and the water return or heat dissipation area of the core layer hydrogel particles is reduced, affecting the heat dissipation effect of the hydrogel microcapsules. If the stirring speed is higher than 500rpm / min, the stirring speed is too high, the particle size of the generated hydrogel microcapsules is smaller, and the particles are easy to agglomerate, affecting the mixing uniformity of the hydrogel composite coating.
[0035] The reaction temperature is 30-60°C, and the reaction time is 5-10 minutes, which is conducive to the polymerization of hydrogel microcapsules with a particle size of 50-150 μm. If the reaction temperature is too low, the reaction cannot be performed; if the reaction temperature is too high, the reactants are hydrolyzed and the stability is reduced. Specifically, the reaction temperature can be 30°C, 35°C, 40°C, 50°C, 60°C, etc., as long as the reaction temperature is within the range of 30-60°C.
[0036] In some preferred embodiments, the stirring speed is 350-450 rpm / min.
[0037] In some preferred embodiments, the stirring speed is 400 rpm / min.
[0038] In some preferred embodiments, the reaction temperature is 30-50° C., and the reaction time is 5-10 min.
[0039] In some preferred embodiments, the reaction temperature is 30° C. and the reaction time is 5 to 10 min.
[0040] In some embodiments, post-processing to obtain the hydrogel microcapsules comprises the following steps: filtering, washing and drying in sequence after the reaction to obtain the hydrogel microcapsules; The washing liquid used for washing includes an alcohol solvent.
[0041] Specifically, after the reaction is completed, the filter is filtered to obtain a filter residue, the filter residue is washed with an alcohol solvent to remove organic matter and water on the surface, and dried to obtain independent granular hydrogel microcapsules; wherein the drying temperature is 70-80° C. and the drying time is 60-90 min.
[0042] Alcohol solvents include ethanol, propanol and the like.
[0043] In some embodiments, the water-based resin includes one or more of epoxy resin, polyurethane resin, and silicone resin. The mass ratio of the aqueous resin to the hydrogel microcapsule is (1:10) to (4:6); The solid content of the water-based resin is 20-35%.
[0044] Specifically, the water-based resin added to the composite coating is the main film-forming substance in the coating, which helps the coating to form a film and improve the hardness and wear resistance of the coating; the water-based resin also has strong adhesion and can be firmly combined with ingredients such as hydrogel microcapsules to form a uniform composite coating, which is beneficial to improve the adhesion between the substrate and the coating.
[0045] The mass ratio of the water-based resin to the hydrogel microcapsules is in the range of (1:10) to (4:6). The more hydrogel microcapsules are added, the more hydrogel microcapsules are contained in the prepared coating. The hydrogel microcapsules evenly distributed in the coating achieve heat dissipation and cooling on the coating surface through evaporation or absorption of water, thereby improving the heat dissipation effect of the coating. Specifically, the mass ratio of the water-based resin to the hydrogel microcapsules can be 1:10, 1:9, 1:5, 1:4, 2:6, 3:6, 4:6, etc., as long as the mass ratio of the water-based resin to the hydrogel microcapsules is in the range of (1:10) to (4:6).
[0046] Solid content refers to the weight percentage of solid components in water-based resin. The solid content of water-based resin is in the range of 20~35%. The viscosity of water-based resin is high, which improves the adhesion between the coating and the substrate, and is conducive to the formation of a dense and durable film layer of the composite coating.
[0047] In some embodiments, the mass ratio of the aqueous resin to the hydrogel microcapsule is 1:(10-20).
[0048] In some embodiments, the mass ratio of the aqueous resin to the hydrogel microcapsules is (1:9) to (4:6).
[0049] In some embodiments, the hydrogel composite coating includes one or more of a thickener, a colorant, and a stabilizer. The thickener, colorant, and stabilizer are commonly used, such as thickeners such as cellulose, polyvinyl alcohol, thickeners, etc., colorants include inorganic pigments (such as iron oxide, carbon black, etc.) and organic pigments (such as phthalocyanine green and phthalocyanine blue, etc.), stabilizers such as commonly used defoamers, leveling agents, adhesion promoters, etc. Stabilizers include cellulose acetate, etc.
[0050] In a second aspect, the present application provides a hydrogel composite coating for heat dissipation, wherein the hydrogel composite coating is obtained by drying the above-mentioned hydrogel composite coating, and the hydrogel microcapsules are arranged in the hydrogel composite coating.
[0051] Specifically, the hydrogel composite coating is formed by coating the hydrogel composite coating on the surface of the substrate by processes such as scraping, spraying, and dipping, and then drying the coating to obtain the hydrogel composite coating.
[0052] The material of the substrate is one of PET, PC, PU, PVC, ABS, silicone, ceramic, and metal alloy.
[0053] The hydrogel microcapsules are arranged in the hydrogel composite coating. As the temperature rises, the water in the inner layer of the hydrogel microcapsules will gradually evaporate, taking away a large amount of heat, and having a good cooling effect on the heat source of the material that needs to be cooled; when the temperature drops, the hydrogel microcapsules will actively absorb and replenish water from the air, and the water in the inner layer of the hydrogel microcapsules can be replenished, which can realize the circulation effect of evaporative heat dissipation and low-temperature water return, and meet the long-term and repeated cooling effect of the hydrogel composite coating used for heat dissipation.
[0054] The hydrogel composite coating for heat dissipation provided in the present application contains an aqueous resin and hydrogel microcapsules. The aqueous resin contained in the hydrogel composite coating has high mechanical strength, and the hydrogel microcapsules contained in the hydrogel composite coating make the hydrogel composite coating have a good heat dissipation effect. At the same time, the shell layer also improves the mechanical properties of the hydrogel microcapsules, overcoming the problems of poor mechanical properties and difficult packaging of existing hydrogel materials, and can be applied to consumer electronics, photovoltaics, energy storage and other fields.
[0055] In some embodiments, the drying temperature is 60-80°C and the drying time is 15-30 min; And / or, the thickness of the hydrogel composite coating is 10 μm to 300 μm.
[0056] Specifically, the hydrogel composite coating formed on the surface of the substrate can be dried at a temperature of 60 to 80° C. to obtain a hydrogel composite coating. Specifically, the drying temperature can be 60° C., 65° C., 70° C., 73° C., 78° C., 80° C., etc., as long as the drying temperature is within the range of 60 to 80° C.
[0057] The thickness of the hydrogel composite coating is in the range of 10 μm to 300 μm, which can cool and dissipate heat on the substrate.
[0058] Specifically, the thickness of the hydrogel composite coating can be 10 μm, 30 μm, 50 μm, 80 μm, 100 μm, 150 μm, 200 μm, 230 μm, 280 μm, 300 μm, etc., as long as the thickness of the hydrogel composite coating is within the range of 10 μm to 300 μm.
[0059] The present invention is further described below by way of examples.
[0060] Example 1 The raw materials were obtained as follows: 60 parts of organic solvent cyclohexane, 3 parts of surfactant Span 80 as shell material, 8 parts of water-soluble monomer hydroxyethyl acrylate, 0.3 parts of cross-linking agent methylenebisacrylamide, 12 parts of hygroscopic component calcium chloride, 0.7 parts of initiator peroxide phenylpropionamide, 0.3 parts of catalyst tetramethylethylenediamine, and 18 parts of water.
[0061] 1) Prepare hydrogel microcapsules as follows: S1: mixing cyclohexane and Span 80 evenly to obtain a first mixed solution; S2: mixing hydroxyethyl acrylate, methylenebisacrylamide, phenylacrylamide peroxide, calcium chloride and water to obtain a second mixed solution; S3: adding the second mixed solution to the first mixed solution, adding tetramethylethylenediamine and reacting with stirring, the stirring speed is 400 rpm / min, the reaction temperature is 30°C, and the reaction time is 10 min; after the reaction, filtering the mixed solution, collecting the filter residue and washing it with ethanol, and drying it after washing to obtain hydrogel microcapsules.
[0062] The particle size of the hydrogel microcapsules prepared in Example 1 is 100 μm.
[0063] 2) Prepare a hydrogel composite coating for heat dissipation as follows: S11: preparing a hydrogel composite coating: uniformly mixing the above-prepared hydrogel microcapsules, water-based resin polyurethane resin, water-soluble red dye and cellulose acetate to obtain a hydrogel composite coating, wherein the mass ratio of the water-based resin to the hydrogel microcapsules is 2:6, and the mass ratio of the water-based resin to the dye and cellulose acetate is 20:0.2:1.
[0064] S21: preparing a hydrogel composite coating for heat dissipation: coating the above-mentioned hydrogel composite coating on the surface of the substrate, and drying at 70° C. for 20 min to obtain a hydrogel composite coating with a thickness of 200 μm.
[0065] Example 2 Most of the steps in this embodiment are the same as those in embodiment 1, except that different raw material components are added, specifically as follows: 70 parts of organic solvent cyclohexane, 1 part of surfactant Span 80, 5 parts of water-soluble monomer hydroxyethyl acrylate, 0.2 parts of cross-linking agent methylene bisacrylamide, 10 parts of hygroscopic component calcium chloride, 0.3 parts of initiator peroxide phenylpropionamide, 0.1 parts of catalyst tetramethylethylenediamine, and 15 parts of water. The hydrogel microcapsules prepared in embodiment 2 have a particle size of 50 μm.
[0066] Example 3 Most of the steps in this embodiment are the same as those in embodiment 1, except that different raw material components are added, specifically as follows: 50 parts of organic solvent cyclohexane, 4 parts of surfactant Span 80, 10 parts of water-soluble monomer hydroxyethyl acrylate, 0.5 parts of cross-linking agent methylenebisacrylamide, 15 parts of hygroscopic component calcium chloride, 1 part of initiator peroxide phenylpropionamide, 0.5 parts of catalyst tetramethylethylenediamine, and 20 parts of water. The hydrogel microcapsules prepared in embodiment 3 have a particle size of 150 μm.
[0067] Example 4 Most of the steps in this example are the same as those in Example 1, except that the stirring speed in step S3 is different, and the stirring speed is 500 rpm / min. The particle size of the hydrogel microcapsules prepared in Example 4 is 80 μm.
[0068] Example 5 Most of the steps in this embodiment are the same as those in embodiment 1, except that the stirring speed in step S3 is different, and the stirring speed is 300 rpm / min. The particle size of the hydrogel microcapsules prepared in embodiment 5 is 120 μm.
[0069] Example 6 Most of the steps in this embodiment are the same as those in embodiment 1, except that the stirring speed in step S3 is different, and the stirring speed is 800 rpm / min. The particle size of the hydrogel microcapsules prepared in embodiment 6 is 20 μm.
[0070] Example 7 Most of the steps in this example are the same as those in Example 1, except that the reaction temperature in step S3 is different, and the reaction temperature is 60° C. The particle size of the hydrogel microcapsules prepared in Example 7 is 180 μm.
[0071] Example 8 Most of the steps in this embodiment are the same as those in embodiment 1, except that the reaction temperature in step S3 is different, and the reaction temperature is 80° C. The particle size of the hydrogel microcapsules prepared in embodiment 8 is 280 μm.
[0072] Example 9 Most of the steps in this example are the same as those in Example 1, except that different raw material components are added, specifically as follows: 2.5 parts of surfactant Span 80. The particle size of the hydrogel microcapsules prepared in Example 9 is 130 μm.
[0073] Example 10 Most of the steps in this example are the same as those in Example 1, except that different raw material components are added, as follows: 20 parts of water. The particle size of the hydrogel microcapsules prepared in Example 10 is 140 μm.
[0074] Embodiment 11 Most of the steps in this embodiment are the same as those in Embodiment 1, except that the types of the components are different. The type of the hygroscopic component is lithium chloride; the surfactant is sodium dodecyl sulfate; the water-soluble monomers are acrylamide, polyvinyl alcohol and carboxymethyl chitosan; and the crosslinking agent is ethylene glycol diacrylate.
[0075] Example 12 Most of the steps in this embodiment are the same as those in Embodiment 1, except that the types of the components are different, the shell material is epoxy resin, the water-soluble monomer is sodium alginate, and the cross-linking agent is ethylene glycol diacrylate.
[0076] Example 13 Most of the steps in this embodiment are the same as those in Embodiment 1, except that in step S11, the mass ratio of the aqueous resin to the hydrogel microcapsule is 1:10; in step S21, the drying temperature is 60° C., the drying time is 15 min, and a hydrogel composite coating with a thickness of 50 μm is obtained.
[0077] Embodiment 14 Most of the steps in this embodiment are the same as those in Embodiment 1, except that in step S11, the mass ratio of the aqueous resin to the hydrogel microcapsule is 4:6; in step S21, the drying temperature is 80° C., the drying time is 30 min, and a hydrogel composite coating with a thickness of 300 μm is obtained.
[0078] Embodiment 15 Most of the steps in this embodiment are the same as those in Embodiment 1, except that in step S11, the mass ratio of the aqueous resin to the hydrogel microcapsule is 1:9; in step S21, the drying temperature is 75° C., the drying time is 22 min, and a hydrogel composite coating with a thickness of 230 μm is obtained.
[0079] Example 16 Most of the steps in this example are the same as those in Example 1, except that different raw material components are added, specifically as follows: 0.5 parts of surfactant Span 80. The particle size of the hydrogel microcapsules prepared in this comparative example is 400 μm.
[0080] Embodiment 17 Most of the steps in this example are the same as those in Example 1, except that different raw material components are added, specifically as follows: 5 parts of surfactant Span 80. The particle size of the hydrogel microcapsules prepared in this comparative example is 106 μm.
[0081] Embodiment 18 Most of the steps in this example are the same as those in Example 1, except that different raw material components are added, as follows: 10 parts of water. The particle size of the hydrogel microcapsules prepared in this comparative example is 80 μm.
[0082] Embodiment 19 Most of the steps in this example are the same as those in Example 1, except that different raw material components are added, specifically as follows: 25 parts of water. The particle size of the hydrogel microcapsules prepared in this comparative example is 210 μm.
[0083] Embodiment 20 Most of the steps in this example are the same as those in Example 1, except that different raw material components are added, specifically as follows: 40 parts of organic solvent cyclohexane, 1 part of surfactant Span 80, 4 parts of water-soluble monomer hydroxyethyl acrylate, 0.1 parts of cross-linking agent methylenebisacrylamide, 9 parts of hygroscopic component calcium chloride, 0.2 parts of initiator peroxide phenylpropionamide, 0.1 parts of catalyst tetramethylethylenediamine, and 15 parts of water. The hydrogel microcapsules prepared in this comparative example have a particle size of 240 μm.
[0084] Embodiment 21 Most of the steps in this example are the same as those in Example 1, except that no hygroscopic component is added. The particle size of the hydrogel microcapsules prepared in this example is 96 μm.
[0085] Embodiment 22 Most of the steps in this example are the same as those in Example 1, except that in step S11, the mass ratio of the aqueous resin to the hydrogel microcapsules is 1:12. The hydrogel composite coating prepared in this comparative example has a thickness of 12 μm.
[0086] Embodiment 23 Most of the steps in this example are the same as those in Example 1, except that the mass ratio of the aqueous resin to the hydrogel microcapsules in step S11 is 4:5; the hydrogel composite coating with a thickness of 450 μm prepared in this comparative example.
[0087] Comparative Example 1 Existing hydrogel materials were purchased and hydrogel particles with a particle size ranging from 50 to 150 μm were obtained by crushing. The method for preparing the hydrogel composite coating for heat dissipation in Comparative Example 1 was the same as that in Example 1, except that the hydrogel particles replaced the hydrogel microcapsules in Example 1.
[0088] Comparative Example 2 Most of the steps in this comparative example are the same as those in Example 1, and the coating thickness is the same, except that no hydrogel microcapsules are added to the composite coating.
[0089] Performance Testing The hydrogel composite coatings prepared in the above comparative examples and embodiments were tested for heat dissipation effect, and the testing method was as follows.
[0090] 1) On a heating plate at a temperature of 50°C, the hydrogel composite coating samples prepared in the above comparative examples and embodiments were respectively pasted, and the size of the samples was (100mm*150mm*0.5mm). The temperature of the sample surface was recorded using a thermocouple, and the maximum cooling temperature and sustainable cooling time of the test samples were tested; the water recovery rate of the sample that can be absorbed from the air after the test sample was left to stand for 1 hour at room temperature (25°C, 60%RH). The sustainable cooling time refers to the total time that the hydrogel microcapsule sample is effectively cooled compared with the blank control group (i.e., comparative example 2) before the hydrogel microcapsules absorb water.
[0091] 2) Test the peel strength between the hydrogel composite coating and the substrate.
[0092] The results of the above tests are shown in Table 1.
[0093] Table 1 From the test results in Table 1, it can be seen that, compared with Example 1 and Comparative Examples 1 and 2, no hydrogel microcapsules are added to Comparative Example 2, and the obtained composite coating has no heat dissipation effect. In Comparative Example 1, directly crushed hydrogel particles are added. Although there is a heat dissipation effect, the crushed hydrogel particles cannot be evenly dispersed in the composite coating, and are very easy to absorb water and bond together, and the peel strength of the coating is poor; the composite coating obtained by the composite coating of Example 1 has a high maximum cooling temperature, a long sustainable cooling time, a high water return rate, and a high peel strength, indicating that hydrogel microcapsules are added to the composite coating, which is a core-shell structure, and the hydrogel particles are in the core layer. The hydrogel microcapsules are independently dispersed microcapsules, will not absorb water and bond, can be evenly dispersed in the composite coating, and increase the surface area of heat dissipation or water return. The hydrogel microcapsules achieve surface heat dissipation and cooling by evaporation or absorption of water, and can achieve a long-term and repeated cooling effect. The shell layer also improves the mechanical properties of the hydrogel microcapsules, so that the hydrogel microcapsules can be mixed with the aqueous resin to prepare the composite coating, thereby improving the mechanical strength of the coating.
[0094] Comparing Examples 1, 4, and 5 with Example 6, the stirring speed of Example 6 is higher than the range of 300-500 rpm / min, the maximum cooling temperature of the composite coating is low, the water return rate is low, and the heat dissipation effect is poor. It is speculated that the stirring speed is too high, the particle size of the hydrogel microcapsules is too small, and adhesion may occur. It means that when the stirring temperature is within the range of 300-500 rpm / min, the particle size of the prepared hydrogel microcapsules is within the range of 50-150 μm, the obtained hydrogel microcapsules have a large heat dissipation or water return surface area, a good heat dissipation effect, and can be cooled repeatedly for a long time.
[0095] Comparing Examples 1 and 7 with Example 8, during the preparation of hydrogel microcapsules, if the reaction temperature is higher than 30-60°C, the temperature is too high, the stability of the gel particles during the preparation process becomes worse and it is easier to agglomerate, resulting in a larger final capsule particle size and a worse bonding strength of the coating.
[0096] By comparing Examples 1 and 9 with Examples 16 and 17, when preparing hydrogel microcapsules, if the amount of shell material added is less than 1-4 parts, the particle size of the obtained hydrogel microcapsules is greater than 50-150 μm, and the water return rate is reduced. It is speculated that the particle size is too large, the specific surface area is reduced, and the water return rate is poor; if the amount of shell material added is higher than 1-4 parts, although the particle size of the obtained hydrogel microcapsules is within the range of 50-150 μm, the thickness of the shell layer is too large, and the water return rate is reduced; This indicates that when the shell material is 1-4 parts, the particle size of the obtained hydrogel microcapsules is within the range of 50-150 μm, and the obtained composite coating has good heat dissipation effect and high water return rate.
[0097] Comparing Examples 1, 10, 18 and 19, when preparing hydrogel microcapsules, if the amount of water added is higher than 10-20 parts, the particle size of the obtained hydrogel microcapsules is greater than 50-150 μm, and the size of the prepared gel particles is greater than 150 um, which does not affect the heat dissipation effect of the coating, but the bonding strength will be reduced, which is not conducive to the coating process.
[0098] Compared with Example 1 and Examples 11 and 12, as long as the organic solvent, catalyst, surfactant, water-soluble monomer, crosslinking agent, hygroscopic component and initiator are within the scope of the present application, a composite coating with good heat dissipation effect, high water return rate and high peel strength can be obtained.
[0099] Compared with Example 20, when preparing hydrogel microcapsules, 50-70 parts of organic solvent, 1-4 parts of shell material, 5-10 parts of water-soluble monomer, 0.2-0.5 parts of cross-linking agent, 10-15 parts of hygroscopic component, 0.3-1 parts of initiator, 0.1-0.5 parts of catalyst, and 15-20 parts of water are used. The obtained composite coating has high water recovery rate, high maximum cooling temperature, high peel strength, and long sustainable cooling time.
[0100] Comparing Example 1 with Example 21, no hygroscopic component was added in Example 21, and the water return rate of the obtained composite coating was extremely low, and the sustainable cooling time was short, indicating that the addition of hygroscopic components in the range of 10 to 15 parts can help to increase the water return rate of the hydrogel microcapsules, so that the water in the core layer of the hydrogel microcapsules can be replenished, and the circulation effect of evaporative heat dissipation and low-temperature water return can be achieved.
[0101] Comparing Examples 1, 13-15 with Examples 22-23, the mass ratio of the aqueous resin to the hydrogel microcapsule is lower than 1:10, the thickness of the obtained hydrogel composite coating is relatively low, and the aqueous resin contained is too low, the peel strength of the coating is too low, and the mass ratio of the aqueous resin to the hydrogel microcapsule is higher than 4:6, the thickness of the obtained hydrogel composite coating is too thick, the lower the water return rate, the shorter the sustainable cooling time, and the lower the heat dissipation effect; this indicates that when the mass ratio of the aqueous resin to the hydrogel microcapsule is in the range of (1:10) to (4:6), the thickness of the obtained hydrogel composite coating is in the range of 10 μm to 300 μm, the obtained composite layer has good heat dissipation effect, high water return rate, high peel strength, and long sustainable cooling time.
[0102] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that the technical solutions described in the above embodiments can still be modified, or some of the technical features can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention.
Claims
1. A hydrogel composite coating, characterized in that: It comprises water-based resin and hydrogel microcapsules. The hydrogel microcapsules are of core-shell structure, including a core layer and a shell layer. The core layer is hydrogel particles, and the shell layer comprises one or more of surfactant, epoxy resin, melamine resin and water-based polyurethane.
2. The hydrogel composite coating according to claim 1, wherein the raw materials for preparing the hydrogel microcapsules include the following components: 50-70 parts of an organic solvent, 1-4 parts of a shell material, 5-10 parts of a water-soluble monomer, 0.2-0.5 parts of a cross-linking agent, 10-15 parts of a hygroscopic component, 0.3-1 parts of an initiator, 0.1-0.5 parts of a catalyst, and 15-20 parts of water, and the shell material includes one or more of a surfactant, an epoxy resin, a melamine resin, and an aqueous polyurethane.
3. The hydrogel composite coating according to claim 2, characterized in that: The organic solvent includes petroleum ether and alkanes, and the alkanes include C6-C10 cycloalkanes and C5-C16 straight-chain alkanes; The catalyst includes tetramethylethylenediamine; The surfactant includes one or more of Span 80, Tween 60, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, cetyltrimethylammonium bromide, and sodium vegetable oleate; The water-soluble monomer includes one or more of acrylamide, acrylic acid, hydroxyethyl acrylate, sodium alginate, polyvinyl alcohol, carboxymethyl chitosan, and guar gum; The cross-linking agent includes one or more of methylene bisacrylamide and ethylene glycol diacrylate; The hygroscopic component includes one or more of calcium chloride and lithium chloride; The initiator includes one or more of ammonium persulfate, phenylpropionamide peroxide, and 1-hydroxycyclohexyl phenyl ketone.
4. The hydrogel composite coating according to claim 2, characterized in that: The preparation method of the hydrogel microcapsule comprises the following steps: Mixing the organic solvent and the shell material to obtain a first mixed solution; Mixing the water-soluble monomer, the cross-linking agent, the initiator, the hygroscopic component and the water to obtain a second mixed solution; The second mixed solution and the first mixed solution are mixed evenly, the catalyst is added to react, and post-processing is performed to obtain the hydrogel microcapsules.
5. The hydrogel composite coating according to claim 4, characterized in that: The step of adding the catalyst to react comprises the following steps: reacting while stirring after adding the catalyst, the stirring speed is 300-500 rpm / min, the reaction temperature is 30-60°C, and the reaction time is 5-10 min.
6. The hydrogel composite coating according to claim 4, characterized in that: The post-processing to obtain the hydrogel microcapsules comprises the following steps: filtering, washing and drying in sequence after the reaction to obtain the hydrogel microcapsules; The washing liquid used for washing includes an alcohol solvent.
7. The hydrogel composite coating according to claim 1, characterized in that: The particle size of the hydrogel microcapsule is 50-150 μm.
8. The hydrogel composite coating according to claim 1, characterized in that: The water-based resin includes one or more of epoxy resin, polyurethane resin, and silicone resin; The mass ratio of the aqueous resin to the hydrogel microcapsule is (1:10) to (4:6); The solid content of the water-based resin is 20-35%.
9. A hydrogel composite coating for heat dissipation, characterized in that: The hydrogel composite coating is obtained by drying the hydrogel composite coating according to any one of claims 1 to 8, and the hydrogel microcapsules are arranged in the hydrogel composite coating.
10. The hydrogel composite coating for heat dissipation according to claim 9, characterized in that: The drying temperature is 60~80℃ and the drying time is 15~30min; And / or, the thickness of the hydrogel composite coating is 10 μm to 300 μm.