Polyurethane composite thermal insulation foam material, preparation method thereof and refrigerator

Abstract

The invention discloses a polyurethane composite thermal insulation foam material, a preparation method thereof and a refrigerator, and belongs to the field of foam thermal insulation materials. The polyurethane composite thermal insulation foam material comprises regenerated polyether polyol, phase change microcapsules, a lipid foaming agent, a catalyst and polymerized MDI, the phase change microcapsule takes long alkyl chain alcohol or alkane as a core and takes silica coupling agent modified silicon dioxide or polyurethane as a shell; the melting points of the long alkyl chain alcohol and the alkane are selected from any one value of 5-20 DEG C; the catalyst comprises an organic metal salt catalyst. The polyurethane heat insulation foam material is applied to the aspect of refrigerator heat insulation materials, solves the problems of high heat conductivity coefficient and poor heat insulation performance of the existing polyurethane heat insulation foam material, and has the characteristics of low foam heat conductivity coefficient and good durability.

Description

Technical Field

[0001] The present invention belongs to the field of foam thermal insulation materials, and particularly relates to a polyurethane composite thermal insulation foam material, a preparation method thereof, and a refrigerator. Background Art

[0002] Polyurethane rigid foam has excellent thermal insulation performance and high specific strength, and is widely used in the refrigeration industry. In the face of the urgent need to continuously improve the thermal insulation performance of refrigerators, the existing mainstream technology is to add VIP boards (vacuum insulation panels) to each outer shell surface of the refrigerator. However, due to the high price of VIP boards, it is of great significance to improve the thermal insulation performance of polyurethane rigid foam in the refrigerator industry.

[0003] Chinese Patent CN116811398A discloses a polyurethane composite board based on phase change thermal insulation and a manufacturing method thereof, including a first panel and a second panel. A phase change polyurethane thermal insulation layer is provided between the first panel and the second panel, and the phase change polyurethane thermal insulation layer has a honeycomb-like porous structure; the phase change polyurethane thermal insulation layer is formed by mixing a phase change composite material and a polyurethane foaming material in a mass ratio of 1:2 and then foaming; the phase change composite material is a third-order phase change composite material, and the third-order phase change composite material is composed of one or more of tetradecane, octadecane, paraffin, and graphene aerogel. It cleverly integrates adiabatic thermal insulation and phase change thermal insulation, not only saving energy but also realizing the recycling of energy, and effectively regulating the indoor living environment of people.

[0004] However, the above-mentioned polyurethane composite board is formed by foaming a phase change aerogel material and a polyurethane foaming material, and there is a problem of leakage after phase change, which affects the reuse of the material. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the technical problem to be solved by the present invention is to overcome the problems of high thermal conductivity and poor thermal insulation performance of the existing polyurethane thermal insulation foam materials, and to provide a polyurethane composite thermal insulation foam material with low foam thermal conductivity and good durability, a preparation method thereof, and a refrigerator.

[0006] To solve the above technical problem, the technical solution adopted by the present invention is as follows:

[0007] On the one hand, the present invention provides a polyurethane composite thermal insulation foam material, including recycled polyether polyol, phase change microcapsules, lipid foaming agent, catalyst, and polymeric MDI;

[0008] The phase change microcapsules have a long alkyl chain alcohol or alkane as the core and silica modified with a siloxane coupling agent or polyurethane as the shell; the melting points of the long alkyl chain alcohol and the alkane are selected from any value in the range of 5-20 °C; the catalyst includes an organic metal salt catalyst.

[0009] Preferably, the long-chain alkyl alcohol is selected from decanol or dodecanol; the alkane is selected from tetradecane and pentadecane; the organometallic salt catalysts include potassium isooctanoate, potassium neodecanoate, and potassium acetate.

[0010] Preferably, the lipid blowing agent includes methyl formate, ethyl formate, and methyl acetate.

[0011] Preferably, the catalyst further includes a blowing catalyst, a gel catalyst, and a trimerization catalyst, and the ratio of the blowing catalyst, the gel catalyst, and the trimerization catalyst is 0.5-1:2-3:1-1.5.

[0012] Preferably, the blowing catalyst includes one or more mixtures of pentamethyldiethylenetriamine, N-methyldicyclohexylamine, tetramethylhexamethylenediamine, bis(dimethylaminoethyl) ether, triethanolamine, dimethylethanolamine, and dibutyltin diol acid ester; the gel catalyst includes one or more mixtures of triethylenediamine, dimethylcyclohexylamine, dibutyltin acetate, methylimidazole, and dimethylimidazole; the trimerization catalyst includes one or more mixtures of N,N',N”-tris(dimethylaminopropyl)-hexahydrotriazine and 2,4,6-tris(dimethylaminomethyl)phenol.

[0013] Preferably, the hydroxyl value of the recycled polyether polyol is 440-570 mgKOH / g, and the viscosity is 900-1900 mPa·s; the polymeric MDI is polymethylene polyphenyl polyisocyanate obtained by polymerizing MDI, and the NCO% is 30-32%.

[0014] On the other hand, the present invention provides a method for preparing the polyurethane composite thermal insulation foam material according to any one of the above technical solutions, including:

[0015] Step 1, fully mixing the phase change microcapsules, the recycled polyether polyol, the catalyst, the surfactant, and water to obtain a dry white material;

[0016] Step 2, fully mixing the dry white material with the hydrocarbon blowing agent and the lipid blowing agent to obtain a white material;

[0017] Step 3, respectively injecting the white material and the polymeric MDI into a high-pressure foaming machine, and injecting them into a mold for foaming to obtain the polyurethane composite thermal insulation foam material.

[0018] Preferably, in Step 1, the surfactant includes at least one of polydimethylsiloxane, polyorganosiloxane-polyoxyethylene copolymer, polyoxyethylene alcohol, polyoxyethylene-polypropylene ketone copolymer, and phosphate ester; the water is deionized water, and the resistivity at 25°C is greater than 18.2 MΩ·cm;

[0019] By weight, the amount of the recycled polyether polyol is selected from any value in the range of 85-91 parts, the amount of the catalyst is selected from any value in the range of 5-8 parts; the amount of the surfactant is selected from any value in the range of 3-5 parts; the amount of water is selected from any value in the range of 1-2 parts; the amount of the organometallic salt catalyst in the catalyst is any value in the range of 1-2 parts; the ratio of the phase change microcapsules to the dry white material is 5-15:100;

[0020] In the second step, the hydrocarbon blowing agent includes a conventional blowing agent and a low-boiling blowing agent. The conventional blowing agent is one or a mixture of cyclopentane, LBA, and HFC-245fa, and the low-boiling blowing agent is one or a mixture of butane, isobutane, tetrafluoroethane, and propane; the ratio of the hydrocarbon blowing agent to the dry white material is 10-20:100; the ratio of the lipid blowing agent to the dry white material is 5-10:100;

[0021] In the third step, the mass ratio of the polymeric MDI to the white material is 1.25-1.50.

[0022] Preferably, in the first step, the phase change microcapsules, the recycled polyether polyol, the catalyst, the surfactant, and water are fully mixed at 18-22 °C and 0.5-1.5 MPa for 2-3 h to obtain the dry white material;

[0023] In the second step, the dry white material is fully mixed with the hydrocarbon blowing agent and the lipid blowing agent at 18-22 °C and 1.5-3.5 MPa to obtain the white material;

[0024] In the third step, the white material and the polymeric MDI are respectively injected into a high-pressure foaming machine, and foamed at 18-22 °C and 120-140 bar into a mold with a mold temperature of 45-50 °C to obtain a polyurethane composite thermal insulation foam material; the mold includes a laboratory standard evaluation mold, a refrigerator cabinet foaming mold, and a refrigerator door body foaming mold.

[0025] The present invention also provides a refrigerator, and the freezer of the refrigerator uses the polyurethane composite thermal insulation foam material described in any of the above technical solutions as the thermal insulation material.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] The present invention provides a polyurethane composite thermal insulation foam material. Through the reaction between the hydroxyl groups of the phase change microcapsules and the isocyanate groups, the microcapsules are fixed in the polyurethane foam to ensure good compatibility. At the same time, by utilizing its unique phase change endothermic property, the thermal insulation effect of the foam is further enhanced. On this basis, a lipid foaming agent is further introduced to reduce the thermal conductivity of the foam and improve the thermal insulation performance. At the same time, aiming at the poor demoulding property caused by recycled polyether and lipid foaming agent, the present invention introduces an organometallic salt catalyst to improve the demoulding performance of the foam and ensure the overall performance of the polyurethane composite thermal insulation foam material. Detailed implementation mode

[0028] The technical solutions in the specific embodiments of the present invention will be described in detail and completely below. Obviously, the described embodiments are only partial specific implementation manners of the overall technical solution of the present invention, rather than all implementation manners. Based on the overall concept of the present invention, all other embodiments obtained by those of ordinary skill in the art fall within the protection scope of the present invention.

[0029] On the one hand, the present invention provides a polyurethane composite thermal insulation foam material, which includes recycled polyether polyol, phase change microcapsules, lipid foaming agent, catalyst, and polymeric MDI; the phase change microcapsules have a long alkyl chain alcohol or alkane as the core and silica modified with a siloxane coupling agent or polyurethane as the shell; the melting points of the long alkyl chain alcohol and alkane are selected from any value in the range of 5-20 °C; the catalyst includes an organometallic salt catalyst. The phase change microcapsules in the polyurethane composite thermal insulation foam material are successfully incorporated into the polyurethane foam by means of chemical bond embedding, showing excellent compatibility, thus significantly reducing the thermal conductivity of the foam. At the same time, by introducing a lipid foaming agent, the thermal insulation performance of the foam is further optimized. In addition, using a trimerization catalyst effectively improves the problem of insufficient demoulding performance caused by the introduction of recycled polyether and lipid foaming agent.

[0030] Phase change materials are a class of materials that can absorb or release a large amount of latent heat during the phase change process. Phase change materials can store or release heat during the phase change process (such as from solid to liquid or from liquid to solid), so they are widely used in applications such as temperature regulation, thermal management, and energy storage. Conventional phase change materials have poor stability during use due to the morphological changes involved in the heat absorption and release processes. Phase change microcapsules are a technology that encapsulates phase change materials in tiny capsules. This encapsulation method can effectively control the process of heat release and absorption of the phase change materials, while improving their stability and service life. The microencapsulation technology can prevent the leakage of phase change materials during use and improve their compatibility in various applications.

[0031] In the above technical solution of the present invention, phase change microcapsules carrying hydroxyl groups are introduced into the recycled polyether polyurethane foam. The phase change microcapsules with a hydroxyl-containing shell can react with the isocyanate in the polyurethane formulation and be embedded in the polyurethane foam through chemical bonds, improving the compatibility between the phase change microcapsules and the polyurethane foam. In the working environment, the polyurethane foam is in contact with the cold plate and the hot plate respectively. There is a gradient temperature distribution in the heat-insulating foam along the heat transfer direction. The overall thermal conductivity of the foam is composed of the thermal conductivities of the foams at different temperature gradients. The thermal conductivity of the polyurethane foam is closely related to the material temperature, and the thermal conductivity of the foam is the lowest at about 10°C. The introduction of the phase change microcapsules can improve the thermal distribution of the foam in the working state, construct a constant temperature zone, ensure that the thermal conductivity of the foam in this area reaches the lowest, and contribute to the optimization of the overall thermal conductivity. Moreover, during the heat transfer process, the phase change material will also absorb a part of the heat for its own phase change, reducing the heat transfer from the hot side to the cold side and improving the heat insulation performance of the foam. Therefore, between the cold and hot plates, the phase change microcapsules absorb part of the heat through their own phase change, and at the same time form a constant temperature zone in the polyurethane foam, reducing the overall thermal conductivity and enhancing the heat insulation performance, thereby reducing the energy consumption of the refrigerator or freezer.

[0032] In addition, in the above polyurethane composite heat-insulating foam material, the reaction between the hydroxyl group of the phase change microcapsules and the isocyanate group fixes the phase change component inside the capsule, avoiding leakage after phase change, improving the durability of the material, meeting the requirements of long-term use of the refrigerator or freezer, and at the same time using the phase change microcapsules to improve the thermal conductivity during the use of the polyurethane foam. Specifically, the phase change microcapsules are used to improve the temperature gradient during the use of the polyurethane heat-insulating foam to reduce the thermal conductivity of the polyurethane foam.

[0033] On this basis, a lipid foaming agent is further introduced into the composite foam. The lipid foaming agent has a small surface tension during the foaming process, promotes the formation and stability of bubbles, produces uniform and dense bubbles, gives the foam a lower thermal conductivity, and improves the heat insulation performance. Using 100% recycled polyether polyol instead of petroleum-based polyether polyol endows the foam with low-carbon environmental protection properties. At the same time, the lipid foaming agent can usually be biodegraded and also has good environmental protection. However, the introduction of recycled polyether polyol will lead to an increase in the heat of reaction of the foam material, which is not conducive to maintaining the inherent shape of the foam after demolding. The introduction of the lipid foaming agent will also exacerbate the severity of this problem. In response, this technical solution introduces a trimerization catalyst of imidazole and organic metal salts into the foam formulation to strengthen the curing process in the later stage of the foam material reaction and ensure the demolding performance of the foam.

[0034] It should be noted that the above technical solution also limits that the melting points of the long-chain alkyl alcohols and alkanes are selected from any value in the range of 5-20 °C. The reason is that the thermal conductivity of the foaming agent is directly related to the ambient temperature. At 5-20 °C, the thermal conductivity of the foaming agent is the lowest, which can reduce the thermal conductivity contribution of the overall foam the most. It can be understood that the melting points of the long-chain alkyl alcohols and alkanes can also be 10 °C, 15 °C and any point value within this range.

[0035] In a preferred embodiment, the long-chain alkyl alcohol is selected from decanol or dodecanol; the alkane is selected from tetradecane and pentadecane; the organometallic salt catalysts include potassium isooctanoate, potassium neodecanoate, and potassium acetate. This technical solution specifically limits the types of long-chain alkyl alcohols. The reason is that lipid materials are solid-liquid phase change materials with high latent heat and good effects; it limits that the alkane is selected from tetradecane and pentadecane. The reason is that the melting point of lipids is directly related to the number of carbon atoms. To ensure that the phase change temperature of the phase change material is within the range of 5-20 °C, the carbon number should be 14 or 15; it limits that the organometallic salt catalysts include potassium isooctanoate, potassium neodecanoate, and potassium acetate. The reason is that organometallic catalysts have high activity, and potassium isooctanoate, potassium neodecanoate, and potassium acetate have better usage effects.

[0036] In a preferred embodiment, the lipid foaming agent includes methyl formate, ethyl formate, and methyl acetate. This technical solution specifically limits the types of lipid foaming agents. Small molecule lipids have low boiling points, which is beneficial to keeping the gas phase components of the lipid foaming agent in the foam.

[0037] In a preferred embodiment, the catalyst also includes a foaming catalyst, a gel catalyst, and a trimerization catalyst, and the ratio of the foaming catalyst, the gel catalyst, and the trimerization catalyst is 0.5-1:2-3:1-1.5. Further, the foaming catalyst includes one or a mixture of more of pentamethyldiethylenetriamine, N-methyldicyclohexylamine, tetramethylhexamethylenediamine, bis(dimethylaminoethyl) ether, triethanolamine, dimethylethanolamine, and dibutyltin glycolate; the gel catalyst includes one or a mixture of more of triethylenediamine, dimethylcyclohexylamine, dibutyltin acetate, methylimidazole, and dimethylimidazole; the trimerization catalyst includes one or a mixture of more of N,N',N”-tris(dimethylaminopropyl)-hexahydrotriazine and 2,4,6-tris(dimethylaminomethyl)phenol.

[0038] In a preferred embodiment, the hydroxyl value of the recycled polyether polyol is 440-570 mgKOH / g, and the viscosity is 900-1900 mPa·s; the polymeric MDI is a polymethylene polyphenyl polyisocyanate obtained by polymerizing MDI, and the NCO% is 30-32%. This technical solution specifically limits the composition of the recycled polyether polyol and the polymeric MDI. The reason is that polyurethane rigid foam materials require a high proportion of rigid structures in the molecular chain and a high degree of crosslinking. Therefore, high-NCO% polymeric MDI and polyols with high hydroxyl values are required.

[0039] On the other hand, the present invention provides a method for preparing the polyurethane composite thermal insulation foam material of any one of the above technical solutions, including:

[0040] Step 1: Fully mix the phase change microcapsules, recycled polyether polyol, catalyst, surfactant, and water to obtain a dry white material;

[0041] Step 2: Fully mix the dry white material with hydrocarbon blowing agents and lipid blowing agents to obtain a white material;

[0042] Step 3: Inject the white material and polymeric MDI into a high-pressure foaming machine respectively, and inject them into a mold for foaming to obtain the polyurethane composite thermal insulation foam material.

[0043] The above technical solution defines that the phase change microcapsules are added in Step 1 instead of in Step 2 or Step 3. The reason is that the compatibility between the blowing agent components mixed in the second step and the dry white material is poor. If the phase change microcapsules are mixed at the same time, the mixing effect is very poor. The third step is the process of foam material reaction and molding. After the black and white materials are mixed, they react to form foam, and the overall process is only 40 - 60 s, and the phase change microcapsules cannot be mixed in.

[0044] In a preferred embodiment, in Step 1, the surfactant includes at least one of polydimethylsiloxane, polyorganosiloxane-polyoxyethylene copolymer, polyoxyethylene alcohol, polyoxyethylene-polyacrylketo copolymer, and phosphate ester (preferably at least one of silicone oil L6863 and silicone oil L6988); the water is deionized water with a resistivity greater than 18.2 MΩ·cm at 25°C; by weight, the dosage of the recycled polyether polyol is selected from any value in the range of 85 - 91 parts, the dosage of the catalyst is selected from any value in the range of 5 - 8 parts; the dosage of the surfactant is selected from any value in the range of 3 - 5 parts; the dosage of the water is selected from any value in the range of 1 - 2 parts; the dosage of the organometallic salt catalyst in the catalyst is selected from any value in the range of 1 - 2 parts; the ratio of the phase change microcapsules to the dry white material is 5 - 15:100; in Step 2, the hydrocarbon blowing agent includes a conventional blowing agent and a low-boiling blowing agent. The conventional blowing agent is one or a mixture of cyclopentane, LBA, and HFC-245fa, and the low-boiling blowing agent is one or a mixture of butane, isobutane, tetrafluoroethane, and propane; the ratio of the hydrocarbon blowing agent to the dry white material is 10 - 20:100; the ratio of the lipid blowing agent to the dry white material is 5 - 10:100; in Step 3, the mass ratio of the polymeric MDI to the white material is 1.25 - 1.50.

[0045] In a preferred embodiment, in step one, the phase change microcapsules, recycled polyether polyol, catalyst, surfactant, and water are fully mixed at 18 - 22°C and 0.5 - 1.5 MPa for 2 - 3 hours to obtain a dry white material; in step two, the dry white material is fully mixed with a hydrocarbon blowing agent and a lipid blowing agent at 18 - 22°C and 1.5 - 3.5 MPa to obtain a white material; in step three, the white material and polymeric MDI are respectively injected into a high-pressure foaming machine and injected into a mold with a mold temperature of 45 - 50°C at 18 - 22°C and 120 - 140 bar for foaming to obtain a polyurethane composite thermal insulation foam material; the mold includes a laboratory standard evaluation mold, a refrigerator cabinet foaming mold, and a refrigerator door body foaming mold.

[0046] The present invention also provides a refrigerator, wherein the freezer of the refrigerator uses the polyurethane composite thermal insulation foam material of any of the above technical solutions as the thermal insulation material. This refrigerator has the characteristics of good thermal insulation performance, environmental friendliness, and durability.

[0047] In order to more clearly and detailedly introduce the polyurethane composite thermal insulation foam material, its preparation method, and the refrigerator provided by the embodiments of the present invention, the following will be described in combination with specific embodiments.

[0048] Example 1

[0049] 1. By weight, the formula is as follows:

[0050] Dry white material (recycled polyether polyol: catalyst: surfactant: water: organometallic salt catalyst = 88:5:4:1.5:1.5)

[0051] Phase change microcapsules (shell layer carrying hydroxyl groups): 11 parts

[0052] Hydrocarbon blowing agent: 10 parts

[0053] Lipid blowing agent: 5 parts

[0054] Polymeric MDI: 143.75 parts

[0055] 2. Mix the materials according to the following steps:

[0056] Step one, fully mix the phase change microcapsules, recycled polyether polyol, catalyst, surfactant, and water to obtain a dry white material;

[0057] Step two, fully mix the dry white material with the hydrocarbon blowing agent and the lipid blowing agent to obtain a white material;

[0058] Step three, respectively inject the white material and polymeric MDI into a high-pressure foaming machine, inject into a mold for foaming, and obtain a polyurethane composite thermal insulation foam material.

[0059] 3. The foam preparation process is as follows:

[0060] After completing the above material mixing process, with a material temperature of 20°C, a gun pressure of 130 bar, and a mold temperature of 47°C, and in accordance with the foaming standard of Step 3, ensure that the gel time of the foam and the free rise density (FRD) are within the designed range. Subsequently, start to find the appropriate filling volume for the mold (size 2000mm * 200mm * 50mm), and then determine the test filling volume with a 15% overfill. Control the mold temperature at 47°C and the curing time at 7 minutes as the standard foaming conditions.

[0061] 4. Test standards:

[0062] Immediately after foaming, cut the foam along the central axis and measure the expansion rate of the foam cross-section. Divide the foam sample into 200mm * 200mm * 50mm sample blocks for standby. Cut off the skin of the standby sample blocks and cut them into 50mm * 50mm * 30mm for density and compressive strength tests, and 10% compressive strength test after aging; cut off the skin of the standby sample blocks and cut them into 200mm * 200mm * 25mm for thermal conductivity test.

[0063] Comparative Example 1

[0064] 1. Formula by weight:

[0065] Dry white material (recycled polyether polyol: catalyst: surfactant: water: organometallic salt catalyst = 89.5:5:4:1.5:0)

[0066] Phase change microcapsules (shell carrying hydroxyl groups): 11 parts

[0067] Hydrocarbon blowing agent: 15 parts

[0068] Lipid blowing agent: 0 parts

[0069] Polymeric MDI: 143.75 parts

[0070] 2. Mix the materials according to the following steps:

[0071] Step 1, fully mix the phase change microcapsules, recycled polyether polyol, catalyst, surfactant, and water to obtain the dry white material;

[0072] Step 2, fully mix the dry white material with the hydrocarbon blowing agent and lipid blowing agent to obtain the white material;

[0073] Step 3, respectively inject the white material and polymeric MDI into a high-pressure foaming machine, and inject them into the mold for foaming to obtain the polyurethane composite thermal insulation foam material.

[0074] 3. The foam preparation process is as follows:

[0075] After completing the above material mixing process, using a material temperature of 20°C, a gun pressure of 130 bar, and a mold temperature of 47°C, according to the foaming standard in Step 3, determine that the gel time of the foam and the free rise density (FRD) are within the design range. Subsequently, start to find the appropriate filling volume for the mold (size 2000mm * 200mm * 50mm), and then determine the test filling volume with a 15% overfill. Control the mold temperature at 47°C and the curing time at 7 minutes, which are the standard foaming conditions.

[0076] 4. Test standards:

[0077] Immediately after foaming, cut the foam along the central axis and measure the expansion rate of the foam cross-section. Divide the foam sample into 200mm * 200mm * 50mm sample blocks for standby. Cut off the skin of the standby sample blocks and cut them into 50mm * 50mm * 30mm for density and compressive strength tests, and 10% compressive strength test after aging; cut off the skin of the standby sample blocks and cut them into 200mm * 200mm * 25mm for thermal conductivity test.

[0078] Comparative Example 2

[0079] 1. By weight, the formula:

[0080] Dry white material (recycled polyether polyol: catalyst: surfactant: water: organometallic salt catalyst = 89.5:5:4:1.5:0)

[0081] Phase change microcapsules (shell layer carrying hydroxyl groups): 11 parts

[0082] Hydrocarbon blowing agent: 10 parts

[0083] Lipid blowing agent: 5 parts

[0084] Polymeric MDI: 143.75 parts

[0085] 2. Mix the materials according to the following steps:

[0086] Step 1, fully mix the phase change microcapsules, recycled polyether polyol, catalyst, surfactant, and water to obtain the dry white material;

[0087] Step 2, fully mix the dry white material with the hydrocarbon blowing agent and lipid blowing agent to obtain the white material;

[0088] Step 3, respectively inject the white material and polymeric MDI into a high-pressure foaming machine, and inject them into the mold for foaming to obtain the polyurethane composite thermal insulation foam material.

[0089] 3. The foam preparation process is as follows:

[0090] After completing the above material mixing process, using a material temperature of 20°C, a gun pressure of 130 bar, and a mold temperature of 47°C, according to the foaming standard in Step 3, determine that the gel time of the foam and the free rise density (FRD) are within the design range. Subsequently, start to find the appropriate filling volume for the mold (size 2000mm * 200mm * 50mm), and then determine the test filling volume according to 15% overfill. Control the mold temperature at 47°C and the curing time at 7 min as the standard foaming conditions.

[0091] 4. Test standards:

[0092] Immediately after foaming, cut the foam along the central axis and measure the expansion rate of the foam cross-section. Divide the foam sample into 200mm * 200mm * 50mm sample blocks for standby. Cut off the skin of the standby sample blocks and cut them into 50mm * 50mm * 30mm for density and compressive strength testing, and 10% compressive strength testing after aging; cut off the skin of the standby sample blocks and cut them into 200mm * 200mm * 25mm for thermal conductivity testing.

[0093] Comparative Example 3

[0094] 1. By weight, the formula:

[0095] Dry white material (petroleum-based polyether polyol: catalyst: surfactant: water: organometallic salt catalyst = 89.5:5:4:1.5:0)

[0096] Phase change microcapsules: 0 parts

[0097] Hydrocarbon blowing agent: 15 parts

[0098] Lipid blowing agent: 0 parts

[0099] Polymeric MDI: 143.75 parts

[0100] 2. Mix the materials according to the following steps:

[0101] Step 1, fully mix the phase change microcapsules, recycled polyether polyol, catalyst, surfactant, and water to obtain the dry white material;

[0102] Step 2, fully mix the dry white material with the hydrocarbon blowing agent and lipid blowing agent to obtain the white material;

[0103] Step 3, respectively inject the white material and polymeric MDI into a high-pressure foaming machine, and inject them into the mold for foaming to obtain the polyurethane composite thermal insulation foam material.

[0104] 3. The foam preparation process is as follows:

[0105] After completing the above material mixing process, with a material temperature of 20°C, a gun pressure of 130 bar, and a mold temperature of 47°C, according to the foaming standard in Step 3, ensure that the gel time of the foam and the free rise density (FRD) are within the designed range. Subsequently, start to find the appropriate filling volume for the mold (size 2000mm * 200mm * 50mm), and then determine the test filling volume with a 15% overfill. Control the mold temperature at 47°C and the curing time at 7 minutes, which are the standard foaming conditions.

[0106] 4. Test Standards:

[0107] Immediately after foaming, cut the foam along the central axis and measure the expansion rate of the foam cross-section. Divide the foam sample into 200mm * 200mm * 50mm sample blocks for standby. Cut off the skin of the standby sample blocks and cut them into 50mm * 50mm * 30mm for density and compressive strength tests, and 10% compressive strength test after aging; cut off the skin of the standby sample blocks and cut them into 200mm * 200mm * 25mm for thermal conductivity test.

[0108] Comparative Example 4

[0109] 1. By weight, the formula:

[0110] Dry white material (recycled polyether polyol: catalyst: surfactant: water: organometallic salt catalyst = 89.5:5:4:1.5:0)

[0111] Phase change microcapsules (shell layer without hydroxyl groups): 11 parts

[0112] Hydrocarbon blowing agent: 15 parts

[0113] Lipid blowing agent: 0 parts

[0114] Polymeric MDI: 143.75 parts

[0115] 2. Mix the materials according to the following steps:

[0116] Step 1, fully mix the phase change microcapsules, recycled polyether polyol, catalyst, surfactant, and water to obtain the dry white material;

[0117] Step 2, fully mix the dry white material with the hydrocarbon blowing agent and lipid blowing agent to obtain the white material;

[0118] Step 3, separately inject the white material and polymeric MDI into a high-pressure foaming machine, and inject them into the mold for foaming to obtain the polyurethane composite thermal insulation foam material.

[0119] 3. The foam preparation process is as follows:

[0120] After completing the above material mixing process, using a material temperature of 20°C, a gun pressure of 130 bar, and a mold temperature of 47°C, according to the foaming standard in Step 3, ensure that the gel time of the foam and the free rise density (FRD) are within the design range. Subsequently, start to find the appropriate filling volume for the mold (size 2000mm * 200mm * 50mm), and then determine the test filling volume with a 15% overfill. Control the mold temperature at 47°C and the curing time at 7 minutes as the standard foaming conditions.

[0121] 4. Test Standards:

[0122] Immediately after foaming, cut the foam along the central axis and measure the expansion rate of the foam cross-section. Divide the foam sample into 200mm * 200mm * 50mm sample blocks for standby. Cut off the skin of the standby sample blocks and cut them into 50mm * 50mm * 30mm for density and compressive strength tests, and 10% compressive strength test after aging; cut off the skin of the standby sample blocks and cut them into 200mm * 200mm * 25mm for thermal conductivity test.

[0123] Performance Test

[0124] The test results of the above examples and comparative examples are shown in Table 1.

[0125] Table 1 Test Results of Foam Performance

[0126]

[0127] It can be found from Table 1 that compared with the existing foam without introducing phase change microcapsules (Comparative Example 3), after introducing phase change microcapsules (without hydroxyl groups on the surface), the thermal conductivity of the foam (Comparative Example 4) decreased significantly, but the compressive strength attenuation was too obvious after the foam aging test. While using phase change microcapsules with hydroxyl groups on the surface, the lower thermal conductivity of the foam (Comparative Example 1) was preserved, and the mechanical property attenuation reached the same level as that of Comparative Example 1. On this basis, further introducing a lipid foaming agent, the thermal conductivity of the foam (Comparative Example 2) decreased further. However, the demolding expansion rates of Comparative Example 1, Comparative Example 2, and Comparative Example 4 were relatively high. In this regard, an organometallic salt catalyst was introduced in Example 1, which improved the demolding expansion rate of the foam while maintaining low thermal conductivity.

Claims

1. A polyurethane composite thermal insulation foam material, characterized in that: Including recycled polyether polyols, phase change microcapsules, lipid blowing agents, catalysts, and polymeric MDI; The phase-change microcapsule has a long alkyl chain alcohol or alkane as a core and a silicon dioxide or polyurethane modified by a silicone coupling agent as a shell; the melting points of the long alkyl chain alcohol and the alkane are selected from any value in the range of 5-20°C; and the catalyst includes an organic metal salt catalyst.

2. The polyurethane composite thermal insulation foam material according to claim 1, characterized in that: The long alkyl chain alcohol is selected from decanol or dodecanol; the alkane is selected from tetradecane and pentadecane; the organic metal salt catalyst includes potassium isooctanoate, potassium neodecanoate and potassium acetate.

3. The polyurethane composite thermal insulation foam material according to claim 1, characterized in that: The lipid foaming agent includes methyl formate, ethyl formate and methyl acetate.

4. The polyurethane composite thermal insulation foam material according to claim 1, characterized in that: The catalyst also includes a foaming catalyst, a gel catalyst and a trimerization catalyst. The ratio of the foaming catalyst, the gel catalyst and the trimerization catalyst is 0.5-1:2-3:1-1.

5.

5. The polyurethane composite thermal insulation foam material according to claim 4, characterized in that: The foaming catalyst includes one or more mixtures of pentamethyldiethylenetriamine, N-methyldicycloethylamine, tetramethylhexanediamine, bis(dimethylaminoethyl)ether, triethanolamine, dimethylethanolamine, and dibutyltin glycolate; the gelling catalyst includes one or more mixtures of triethylenediamine, dimethylcyclohexylamine, dibutyltin acetate, methylimidazole, and dimethylimidazole; the trimerization catalyst includes one or more mixtures of N,N',N"-tris(dimethylaminopropyl)-hexahydrotriazine and 2,4,6-tris(dimethylaminomethyl)phenol.

6. The polyurethane composite thermal insulation foam material according to claim 1, characterized in that: The regenerated polyether polyol has a hydroxyl value of 440-570 mgKOH / g and a viscosity of 900-1900 mPa·s; the polymeric MDI is polymethylene polyphenyl polyisocyanate obtained by polymerizing MDI, and the NCO% is 30-32%.

7. A method for preparing the polyurethane composite thermal insulation foam material according to any one of claims 1 to 6, characterized in that: include: Step 1, fully mixing the phase change microcapsules, the regenerated polyether polyol, the catalyst, the surfactant and water to obtain a dry white material; Step 2, fully mixing the dry white material with the hydrocarbon foaming agent and the lipid foaming agent to obtain a white material; Step three, respectively putting the white material and the polymerized MDI into a high-pressure foaming machine, injecting them into a mold for foaming, and obtaining a polyurethane composite thermal insulation foam material.

8. The method for preparing the polyurethane composite thermal insulation foam material according to claim 7, characterized in that: In the step 1, the surfactant includes at least one of polydimethylsiloxane, polysiloxane-polyoxyethylene copolymer, polyoxyethylene alcohol, polyoxyethylene-polypropylene ketone copolymer, and phosphate ester; the water is deionized water, and the resistivity at 25° C. is greater than 18.2 MΩ·cm; In parts by weight, the amount of the regenerated polyether polyol is selected from any value in the range of 85-91 parts, the amount of the catalyst is selected from any value in the range of 5-8 parts; the amount of the surfactant is selected from any value in the range of 3-5 parts; the amount of water is selected from any value in the range of 1-2 parts; the amount of the organic metal salt catalyst in the catalyst is any value in the range of 1-2 parts; the ratio of the phase change microcapsules to the dry white material is 5-15:100; In the step 2, the hydrocarbon foaming agent comprises a conventional foaming agent and a low-boiling-point foaming agent, the conventional foaming agent is a mixture of one or more of cyclopentane, LBA, and HFC-245fa, and the low-boiling-point foaming agent is a mixture of one or more of butane, isobutane, tetrafluoroethane, and propane; the ratio of the hydrocarbon foaming agent to the dry white material is 10-20:100; the ratio of the lipid foaming agent to the dry white material is 5-10:100; In the step three, the mass ratio of the polymeric MDI to the white material is 1.25-1.

50.

9. The method for preparing the polyurethane composite thermal insulation foam material according to claim 7, characterized in that: In the step 1, the phase change microcapsules, the regenerated polyether polyol, the catalyst, the surfactant and the water are fully mixed at 18-22° C. and 0.5-1.5 MPa for 2-3 hours to obtain the dry white material; In the step 2, the dry white material is fully mixed with the hydrocarbon foaming agent and the lipid foaming agent at 18-22° C. and 1.5-3.5 MPa to obtain the white material; In the step three, the white material and the polymerized MDI are respectively injected into a high-pressure foaming machine, and injected into a mold with a mold temperature of 45-50°C at 18-22°C and 120-140 bar for foaming to obtain a polyurethane composite thermal insulation foam material; the mold includes a laboratory standard evaluation mold, a refrigerator body foaming mold, and a refrigerator door body foaming mold.

10. A refrigerator, characterized in that: The freezer of the refrigerator adopts the polyurethane composite thermal insulation foam material according to any one of claims 1 to 6 as the thermal insulation material.

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