Polyurethane composition, polyurethane foam, preparation method of polyurethane foam and refrigeration equipment

Abstract

The invention provides a polyurethane composition, polyurethane foam, a preparation method of the polyurethane foam and refrigeration equipment. The polyurethane composition comprises polyether polyol, modified epoxy resin, a foaming agent and isocyanate, wherein the modified epoxy resin is epoxy resin modified by gamma-aminopropyl triethoxy silane and gamma-glycidyl ether oxypropyl trimethoxy silane. According to the invention, the embrittlement resistance of the polyurethane foam in an environment of-60 DEG C can be improved.

Description

Technical Field

[0001] This application belongs to the field of polyurethane technology, and particularly relates to a polyurethane composition, polyurethane foam and its preparation method, and refrigeration equipment. Background Technology

[0002] The transport of biological samples (such as stem cells and viral strains) usually requires ultra-deep cryogenic insulation conditions of -60°C. Currently, polyurethane foam is a commonly used insulation material. However, the shrinkage rate of existing polyurethane foam in the -60°C environment is ≥2.5%. This high shrinkage rate can easily cause the insulation layer to become brittle and crack, thus exposing the biological sample to an unstable temperature environment, ultimately leading to sample failure.

[0003] Therefore, there is an urgent need to develop a polyurethane foam material with higher resistance to embrittlement in order to reduce the shrinkage rate of polyurethane foam in an environment of -60℃. Summary of the Invention

[0004] This application provides a polyurethane composition, a polyurethane foam, a method for preparing the same, and a refrigeration device to improve the anti-embrittlement properties of polyurethane foam at -60°C.

[0005] In a first aspect, embodiments of this application provide a polyurethane composition comprising a polyether polyol, a modified epoxy resin, a foaming agent, and an isocyanate, wherein the modified epoxy resin is an epoxy resin modified with γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane.

[0006] Optionally, the polyurethane composition comprises, by weight parts: 100 parts of the polyether polyol; 10 to 14 parts of the modified epoxy resin; 10.3 to 11.9 parts of the foaming agent; and 140 to 150 parts of the isocyanate.

[0007] Optionally, the modified epoxy resin has a silicon content of 1.8% to 2.2%; and / or, the modified epoxy resin includes one or more of modified bisphenol A epoxy resin and modified phenolic epoxy resin.

[0008] Optionally, the polyether polyol comprises sucrose polyether polyol, hydroxyl-terminated polybutadiene, and nano-SiO2-modified hydroxyl-terminated polybutadiene, wherein the mass ratio of the sucrose polyether polyol, the hydroxyl-terminated polybutadiene, and the nano-SiO2-modified hydroxyl-terminated polybutadiene is (28~32):(6~10):(3~7); and / or, the foaming agent comprises methyl formate, dimethyl carbonate, methyl lactate, and polyglycerol ricinoleate, wherein the mass ratio of the methyl formate, dimethyl carbonate, methyl lactate, and polyglycerol ricinoleate is (6~7):(3~4):(1~2):(0.3~0.5); wherein the methyl lactate is prepared by fermentation of plant starch, and the plant starch comprises One or more of corn starch, rice starch, and wheat starch; and / or, by weight, the polyurethane composition further comprises 2.75 to 4.05 parts of a catalyst; the catalyst comprises pentamethyldiethylenetriamine, a diol solution of modified bis(dimethylaminoethyl) ether, bis(dimethylaminoethyl) ether, and 2-hydroxy-N,N,N-trimethyl-1-propylcarbamate, wherein the mass ratio of pentamethyldiethylenetriamine, the diol solution of modified bis(dimethylaminoethyl) ether, bis(dimethylaminoethyl) ether, and 2-hydroxy-N,N,N-trimethyl-1-propylcarbamate is (0.45~0.55):(0.25~0.35):(1.5~2.5):(0.55~ 0.65); and / or, by weight, the polyurethane composition further comprises 0.35 to 0.55 parts of an antioxidant, the antioxidant comprising pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris(2,4-di-tert-butylphenyl) phosphite, and vitamin E, wherein the mass ratio of pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris(2,4-di-tert-butylphenyl) phosphite, and vitamin E is (0.2 to 0.3):(0.1 to 0.15):(0.05 to 0.1); and / or, by weight, the polyurethane composition further comprises 2.5 to 3.0 parts of silicone oil containing Si-C bonds; and / or, by weight, the polyurethane composition further comprises 2.2 to 2.6 parts of deionized water.

[0009] Secondly, embodiments of this application also provide a polyurethane foam, which is obtained by foaming the above-mentioned polyurethane composition.

[0010] Optionally, the polyurethane foam has a thermal conductivity of less than 22.3 mW / (mK) at 10℃, a thermal conductivity of less than 22.8 mW / (mK) at -60℃, and an interfacial bonding strength greater than 1.02 MPa.

[0011] Thirdly, embodiments of this application also provide a method for preparing polyurethane foam, the method comprising the following steps: S100. Mix polyether polyol and modified epoxy resin to obtain a premixed liquid, wherein the modified epoxy resin is an epoxy resin modified with γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane. S200. The premixed liquid is mixed with a foaming agent to obtain a foamed mixture; S300. The foaming mixture is mixed with isocyanate to obtain a polyurethane composition; S400. The polyurethane composition is subjected to foaming treatment to obtain polyurethane foam.

[0012] Optionally, the modified epoxy resin is prepared by the following method: first, γ-aminopropyltriethoxysilane is mixed with epoxy resin and reacted at a first temperature for a first time; then, γ-glycidoxypropyltrimethoxysilane is added and reacted at the first temperature for a second time to obtain the modified epoxy resin.

[0013] Optionally, the mass ratio of the epoxy resin, the γ-aminopropyltriethoxysilane, and the γ-glycidoxypropyltrimethoxysilane is 100:(2.5~3.5):(1.5~2.5); and / or, the first temperature is 80℃~90℃, the first time is 30min~35min, and the second time is 60min~65min; and / or, the epoxy resin includes one or more of bisphenol A epoxy resin and phenolic epoxy resin.

[0014] Optionally, step S100 includes: adding polyether polyol and modified epoxy resin into a microwave high-pressure reactor and stirring evenly at a second temperature to obtain a premixed solution; The foaming agent includes methyl formate, dimethyl carbonate, methyl lactate, and polyglycerol ricinoleate, and step S200 includes: S201. Add methyl formate to the premixed liquid, control the microwave high-pressure reactor to start dual-frequency microwave coupling heating, and perform gradient pressure increase and stirring; S202. Continue to add dimethyl carbonate, methyl lactate and polyglycerol ricinoleate, control the microwave high-pressure reactor to start dual-frequency microwave coupling heating, and perform gradient pressure increase and stirring.

[0015] Optionally, in step S100, the second temperature is 23℃~28℃, the stirring speed is 550r / min~600r / min, and the stirring time is 1h~1.2h; and / or, adding the polyether polyol and modified epoxy resin to the microwave high-pressure reactor includes: adding the polyether polyol, modified epoxy resin, catalyst, antioxidant, and deionized water to the microwave high-pressure reactor.

[0016] Optionally, in step S201, controlling the microwave high-pressure reactor to activate dual-frequency microwave coupled heating and perform gradient pressurization and stirring includes: controlling the microwave high-pressure reactor to activate two microwave frequencies of 2.4GHz~2.5GHz and 0.91GHz~0.92GHz respectively for coupled heating, with a microwave power of 140W~160W, the pressure increasing from 0.75bar~0.85bar at a rate of 0.15bar / min~0.25bar / min to 1.45bar~1.55bar, stirring at a speed of 550r / min~600r / min, and maintaining the temperature at 23℃~28℃ for 1h~1.2h. h; In step S202, controlling the microwave high-pressure reactor to start dual-frequency microwave coupling heating and perform gradient pressure increase and stirring includes: controlling the microwave high-pressure reactor to start two microwaves with frequencies of 2.4GHz~2.5GHz and 0.91GHz~0.92GHz respectively for coupled heating, with microwave power of 170W~190W, pressure increasing from 1.95bar~2.05bar at a rate of 0.25bar / min~0.35bar / min to 2.95bar~3.05bar, stirring at a speed of 650r / min~700r / min, and holding at 23℃~28℃ for 0.5h~0.6h.

[0017] Optionally, step S400 includes: injecting the polyurethane composition into a mold through a high-pressure foaming machine, and sequentially performing hot air curing treatment, low-temperature setting treatment, and room temperature curing treatment to obtain polyurethane foam; wherein the temperature of the hot air curing treatment is 58℃~62℃, the temperature of the low-temperature setting treatment is -8℃~-12℃, and the time of the room temperature curing treatment is 23℃~28℃. Optionally, the hot air curing treatment time is 2h~2.2h; and / or, the low temperature setting treatment time is 1h~1.2h; and / or, the room temperature curing treatment time is 20h~22h.

[0018] Fourthly, embodiments of this application also provide a refrigeration device, the refrigeration device comprising the polyurethane foam described above, or the refrigeration device comprising polyurethane foam prepared by the polyurethane foam preparation method described above.

[0019] The polyurethane composition, polyurethane foam, preparation method, and refrigeration equipment provided in this application utilize a modified epoxy resin obtained by modifying γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane. γ-aminopropyltriethoxysilane provides flexible siloxane chains, while γ-glycidoxypropyltrimethoxysilane provides epoxy groups to increase the crosslinking density with polyurethane. The combination of γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane enables the polyurethane foam to form a gradient IPN (Interpenetrating Polymer Network) structure with high epoxy content in the cell walls and high polyurethane content in the cell core. This improves the anti-brittleness of the cell walls, while the high toughness of the polyurethane in the cell core buffers cryogenic stress, reduces stress concentration in the cell walls, and further reduces the risk of brittleness. This results in no cell rupture at -60°C, reduced shrinkage, and more stable thermal conductivity, thereby improving the anti-brittleness performance of the polyurethane foam at -60°C. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of this application. Those skilled in the art can obtain other drawings based on these drawings without creative effort. In the following description, the same reference numerals denote the same parts.

[0021] Figure 1 This is a flowchart illustrating the preparation method of polyurethane foam provided in an embodiment of this application. Detailed Implementation

[0022] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0023] In the description of this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Additionally, in the description of this application, the term "comprising" means "including but not limited to". The term "exemplary" is used to mean "serving as an example, illustration, or description," and any embodiment described as "exemplary" is not necessarily to be construed as being more preferred or advantageous than other embodiments. The term "and / or" includes any and all combinations of one or more of the associated listed items. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features; thus, features defined as "first" or "second" may explicitly or implicitly include one or more of the stated features.

[0024] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, which applies regardless of the range.

[0025] This application provides a polyurethane composition comprising a polyether polyol, a modified epoxy resin, a foaming agent, and an isocyanate. The modified epoxy resin is an epoxy resin modified with γ-aminopropyltriethoxysilane (KH-550) and γ-glycidoxypropyltrimethoxysilane (KH-560).

[0026] The polyurethane composition provided in this application uses a modified epoxy resin obtained by modifying γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane. γ-aminopropyltriethoxysilane provides flexible siloxane chains, while γ-glycidoxypropyltrimethoxysilane provides epoxy groups to increase the crosslinking density with the polyurethane. The combination of γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane allows the polyurethane foam to form a gradient IPN (Interpenetrating Polymer Network) structure with "high epoxy content in the cell walls and high polyurethane content in the cell core." This improves the anti-brittleness of the cell walls, while the high toughness of the polyurethane in the cell core buffers cryogenic stress, reduces stress concentration in the cell walls, and further reduces the risk of brittleness. This results in no cell rupture at -60°C, reduced shrinkage, and more stable thermal conductivity, thereby improving the anti-brittleness performance of the polyurethane foam at -60°C. In some embodiments of this application, the modified epoxy resin may include one or more of modified bisphenol A epoxy resin and modified phenolic epoxy resin. Specifically, the modified epoxy resin may include one or more of bisphenol A epoxy resin modified with γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane, and one or more of phenolic epoxy resin modified with γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane. The modified bisphenol A epoxy resin may include one or more of modified bisphenol A epoxy resin E-44 and modified bisphenol A epoxy resin E-51, and the modified phenolic epoxy resin may include one or more of modified phenolic epoxy resin F-44 and modified phenolic epoxy resin F51.

[0027] Specifically, the modified epoxy resin has a molecular weight of 550-650 and a viscosity of 6500 mPa. s~7500mPa For example, the molecular weight of the modified epoxy resin can be 550, 560, 570, 580, 590, 600, 610, 620, 630, 640, 650 or any range between two of the aforementioned values, and the viscosity can be 6500 mPa. s, 6600mPa s, 6700mPa s, 6800mPa s, 6900mPa s, 7000mPa s, 7100mPa s, 7200mPa s, 7300mPa s, 7400mPa s, 7500mPa s or the range between any two of the aforementioned values, etc.

[0028] Optionally, the modified epoxy resin has a silicon content of 1.8% to 2.2%. By controlling the silicon content of the modified epoxy resin to be between 1.8% and 2.2%, a silicon content of 1.8% to 2.2% can form a uniform "island structure," dispersing stress concentration points, thereby reducing the risk of brittle fracture and improving the brittleness resistance of the polyurethane foam. For example, the silicon content of the modified epoxy resin can be 1.8%, 1.9%, 2%, 2.1%, 2.2%, or any range between two of the aforementioned values.

[0029] In some embodiments of this application, the polyurethane composition comprises, by weight, 100 parts of the polyether polyol, 10 to 14 parts of the modified epoxy resin, 10.3 to 11.9 parts of the blowing agent, and 140 to 150 parts of the isocyanate. By controlling the proportions of each raw material in the polyurethane composition within the above-mentioned range, it is beneficial to improve the brittleness resistance of the polyurethane foam.

[0030] For example, by weight, the modified epoxy resin can be 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, or any range between any two of the aforementioned values; the foaming agent can be 10.3 parts, 10.5 parts, 10.7 parts, 10.9 parts, 11.1 parts, 11.3 parts, 11.5 parts, 11.7 parts, 11.9 parts, or any range between any two of the aforementioned values; and the isocyanate can be 140 parts, 141 parts, 142 parts, 143 parts, 144 parts, 145 parts, 146 parts, 147 parts, 148 parts, 149 parts, 150 parts, or any range between any two of the aforementioned values.

[0031] Optionally, the polyether polyol includes sucrose polyether polyol, hydroxyl-terminated polybutadiene (HTPB), and nano-SiO2-modified hydroxyl-terminated polybutadiene. The particle size of the nano-SiO2-modified hydroxyl-terminated polybutadiene is 45 nm to 55 nm, and the mass ratio of the sucrose polyether polyol, the hydroxyl-terminated polybutadiene, and the nano-SiO2-modified hydroxyl-terminated polybutadiene is (28~32):(6~10):(3~7). By setting the polyether polyol to include sucrose polyether polyol, hydroxyl-terminated polybutadiene, and nano-SiO2-modified hydroxyl-terminated polybutadiene within the above-mentioned mass ratio range, the viscosity of the polyurethane composition can be reduced, thereby improving the interfacial adhesion of the polyurethane foam and reducing the void ratio.

[0032] For example, the mass ratio of the sucrose polyether polyol, the hydroxyl-terminated polybutadiene, and the nano-SiO2 modified hydroxyl-terminated polybutadiene can be 30:8:5, 28:10:3, 32:6:5, or 30:6:7, etc.; the particle size of the nano-SiO2 modified hydroxyl-terminated polybutadiene can be 45nm, 46nm, 47nm, 48nm, 49nm, 50nm, 51nm, 52nm, 53nm, 54nm, 55nm, or any range between the aforementioned two values, etc.

[0033] Optionally, the viscosity of the polyurethane composition is between 1900 mPa·s and 2100 mPa·s, for example, it can be 1900 mPa·s, 1950 mPa·s, 2000 mPa·s, 2050 Pa·s, 2100 mPa·s, or any range between two of the aforementioned values. Testing has shown that, within the viscosity range of 1900 mPa to 2100 mPa·s, the polyurethane composition achieves a filling flow rate of 12 mL / s in a 6 mm to 8 mm mold, with a void ratio ≤0.5%. The hydroxyl value of the sucrose polyether polyol can be 380 mg KOH / g to 400 mg KOH / g, for example, 380 mg KOH / g, 385 mg KOH / g, 390 mg KOH / g, 395 mg KOH / g, 400 mg KOH / g, or any range between two of the aforementioned values; the hydroxyl value of the terminal hydroxyl polybutadiene can be 45 mg KOH / g to 55 mg KOH / g, for example, 45 mg KOH / g, 46 mg KOH / g, 47 mg KOH / g, 48 mg KOH / g, 49 mg KOH / g, 55 mg KOH / g, or any range between two of the aforementioned values.

[0034] The nano-SiO2 modified hydroxyl-terminated polybutadiene can be prepared by the following method: (1) Raw material preparation: Weigh out 93-96 parts of hydroxyl-terminated polybutadiene, 3-5 parts of nano-SiO2 (particle size 45nm-55nm), 0.2-0.5 parts of surfactant (e.g., Span 80), 2-4 parts of plasticizer (e.g., dioctyl adipate), and 4.0-4.5 parts of curing agent (e.g., isophorone diisocyanate); (2) Pretreatment: Preheat the hydroxyl-terminated polybutadiene to 50℃~55℃, stir for 2h~3h under vacuum degree ≤-0.090MPa to dehydrate and remove bubbles; dissolve the surfactant in the plasticizer, add nano SiO2 and stir evenly, heat to 50℃~55℃ to make a mixture; (3) Mixing reaction: The dehydrated hydroxyl-terminated polybutadiene is stirred evenly with the mixture, and then a curing agent is added and stirring is continued. The mixture is kept at a constant temperature of 50℃~55℃ to obtain the mixture. (4) Molding and curing: The mixture is vacuum cast (temperature 53℃~58℃, vacuum degree ≤-0.092MPa), and then heated at 50℃~60℃ for 12h~15h to cure, thus obtaining nano-SiO2 modified hydroxyl-terminated polybutadiene.

[0035] Optionally, the foaming agent includes methyl formate, dimethyl carbonate, methyl lactate, and polyglycerol ricinoleate, wherein the mass ratio of methyl formate, dimethyl carbonate, methyl lactate, and polyglycerol ricinoleate is (6~7):(3~4):(1~2):(0.3~0.5); wherein the methyl lactate is prepared by fermentation of plant starch, and the plant starch includes one or more of corn starch, rice starch, and wheat starch. This configuration can increase the bio-based content of the polyurethane composition (≥30%), thereby making the polyurethane foam prepared using the polyurethane composition of this application more environmentally friendly and in line with sustainable development requirements.

[0036] Furthermore, the methyl lactate possesses a high dipole moment, which allows it to form strong intermolecular forces with the methyl formate and dimethyl carbonate, inhibiting the escape of the foaming agent at -60°C and thus reducing the escape rate of the foaming agent at this temperature. Simultaneously, the high dipole moment of the methyl lactate also helps reduce the stratification rate. The polyglycerol ricinoleate improves the compatibility between the methyl lactate and the methyl formate, ensuring uniform cell structure and thereby reducing or avoiding stratification, resulting in a stratification rate ≤0.2%.

[0037] For example, the mass ratio of methyl formate, dimethyl carbonate, methyl lactate, and polyglycerol ricinoleate can be 7:3:1.5:0.4, 6:4:1:0.3, or 6.5:3.5:2:0.5, etc., and can be adjusted according to the application scenario. Methyl formate can be prepared by corn fermentation, and polyglycerol ricinoleate can be prepared by castor oil extraction, thereby increasing the bio-based content of the polyurethane foam and making it more environmentally friendly.

[0038] Optionally, the polyurethane composition further comprises 2.75 to 4.05 parts by mass of a catalyst; the catalyst comprises pentamethyldiethylenetriamine (PC-5), a diol solution of modified bis(dimethylaminoethyl) ether (DY-225), bis(dimethylaminoethyl) ether (PC-8), and 2-hydroxy-N,N,N-trimethyl-1-propylcarbamate (TMR-2), wherein the mass ratio of the pentamethyldiethylenetriamine, the diol solution of modified bis(dimethylaminoethyl) ether, bis(dimethylaminoethyl) ether, and 2-hydroxy-N,N,N-trimethyl-1-propylcarbamate is (0.45 to 0.55):(0.25 to 0.35):(1.5 to 2.5):(0.55 to 0.65). By setting the catalyst to include pentamethyldiethylenetriamine, a diol solution of modified bis(dimethylaminoethyl) ether, bis(dimethylaminoethyl) ether, and 2-hydroxy-N,N,N-trimethyl-1-propylcarbamate in the above-mentioned mass ratio range, the reaction rate can be controlled, thereby improving the anti-embrittlement performance of polyurethane foam at -60°C.

[0039] For example, the mass fraction of the catalyst can be 2.75 parts, 3.05 parts, 3.4 parts, 3.75 parts, 4.05 parts, or any range between two of the aforementioned values; the mass ratio of the pentamethyldiethylenetriamine, the modified bis(dimethylaminoethyl) ether diol solution, the bis(dimethylaminoethyl) ether, and 2-hydroxy-N,N,N-trimethyl-1-propylaminocarbamate can be 0.5:0.3:2.0:0.6, 0.55:0.35:1.5:0.55, or 0.45:0.25:2.5:0.65, etc.

[0040] In some embodiments of this application, the polyurethane composition further includes 0.35 to 0.55 parts by weight of antioxidants, which include pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (referred to as antioxidant 1010), tris(2,4-di-tert-butylphenyl) phosphite (referred to as antioxidant 168) and vitamin E. The mass ratio of pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris(2,4-di-tert-butylphenyl) phosphite and vitamin E is (0.2 to 0.3):(0.1 to 0.15):(0.05 to 0.1). Among them, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] captures free radicals and inhibits the initiation of oxidation chains; tris(2,4-di-tert-butylphenyl)phosphite can decompose hydrogen peroxide, prevent chain growth, and improve antioxidant efficiency; vitamin E can supplement antioxidant activity, prolong the antioxidant cycle, and also further increase the content of bio-based components.

[0041] It is understandable that the existing polyurethane foam has a 2000-hour high temperature and high humidity (60℃+95%RH) compressive strength retention rate of ≤75%, which cannot meet the requirements of long-term use (i.e., 10-year service life) of refrigeration equipment; however, this application can improve the 2000-hour compressive strength retention rate of polyurethane foam (up to about 88%) by using the aforementioned antioxidant, thus meeting the requirements of long-term use.

[0042] For example, the mass ratio of the tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] pentaerythritol ester, the tris(2,4-di-tert-butylphenyl) phosphite, and the vitamin E can be 0.25:0.12:0.08, 0.2:0.15:0.05, or 0.3:0.1:0.1, etc.

[0043] Optionally, the polyurethane composition further comprises 2.5 to 3.0 parts by weight of silicone oil containing Si-C bonds. Using silicone oil containing Si-C bonds as a foam stabilizer can improve cell stability and facilitate the formation of a cross-linked framework. Exemplarily, the mass fraction of the silicone oil containing Si-C bonds can be 2.5 parts, 2.6 parts, 2.7 parts, 2.8 parts, 2.9 parts, 3.0 parts, or any range between any two of the aforementioned values. Specifically, the silicone oil containing Si-C bonds can be selected from one or more silicone oils with the following specifications: AK8812, B8465, B8474, B8481, AK8830, LK665, AK8801, AK8805, and AK8803.

[0044] Optionally, the polyurethane composition further includes 2.2 to 2.6 parts by weight of deionized water. Adding deionized water facilitates the adaptation of the polyurethane composition to high-pressure foaming, enabling the production of polyurethane foam through foaming. Exemplarily, the weight of the deionized water can be 2.2, 2.3, 2.4, 2.5, 2.6 parts, or any range between the aforementioned values.

[0045] This application also provides a polyurethane foam, which is obtained by foaming the above-described polyurethane composition. Since this polyurethane foam adopts all the technical solutions of all the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated upon here.

[0046] Specifically, the thermal conductivity of the polyurethane foam at 10℃ is less than 22.3 mW / (mK), the thermal conductivity of the polyurethane foam at -60℃ is less than 22.8 mW / (mK), and the interfacial bonding strength of the polyurethane foam is greater than 1.02 MPa.

[0047] This application also provides a method for preparing polyurethane foam, which can be applied to the preparation of the polyurethane foam provided in this application. For example... Figure 1 As shown, the method for preparing the polyurethane foam includes the following steps: S100. Mix polyether polyol and modified epoxy resin to obtain a premixed liquid, wherein the modified epoxy resin is an epoxy resin modified with γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane. S200. The premixed liquid is mixed with a foaming agent to obtain a foamed mixture; S300. The foaming mixture is mixed with isocyanate to obtain a polyurethane composition; S400. The polyurethane composition is subjected to foaming treatment to obtain polyurethane foam.

[0048] In some embodiments of this application, the modified epoxy resin can be prepared by the following method: first, γ-aminopropyltriethoxysilane is mixed with epoxy resin and reacted at a first temperature for a first time; then, γ-glycidoxypropyltrimethoxysilane is added, and the reaction continues at the first temperature for a second time to obtain the modified epoxy resin. By controlling the order of addition of γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane, i.e., adding γ-aminopropyltriethoxysilane first to react with the epoxy resin, and then adding γ-glycidoxypropyltrimethoxysilane for further reaction, it is beneficial to form a gradient distribution of silicon content from the foam surface to the core layer, construct a gradient IPN structure, and thus improve the anti-embrittlement performance of polyurethane foam at -60°C.

[0049] Optionally, the epoxy resin includes one or more of bisphenol A epoxy resin and phenolic epoxy resin. Specifically, the bisphenol A epoxy resin may include one or more of bisphenol A epoxy resin E-44 and bisphenol A epoxy resin E-51, and the phenolic epoxy resin may include one or more of phenolic epoxy resin F-44 and phenolic epoxy resin F51.

[0050] Optionally, in step S100, the mass ratio of the epoxy resin, the γ-aminopropyltriethoxysilane, and the γ-glycidoxypropyltrimethoxysilane is 100:(2.5~3.5):(1.5~2.5). Exemplarily, the mass ratio of the epoxy resin, the γ-aminopropyltriethoxysilane, and the γ-glycidoxypropyltrimethoxysilane can be 100:3:2, 100:3.5:1.5, or 100:2.5:2.5, etc.

[0051] Optionally, the first temperature is 80℃~90℃, the first time is 30min~35min, and the second time is 60min~65min. For example, the first temperature can be 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, 86℃, 87℃, 88℃, 89℃, 90℃, or any range between any two of the aforementioned values; the first time can be 30min, 31min, 32min, 33min, 34min, 35min, or any range between any two of the aforementioned values; and the second time can be 60min, 61min, 62min, 63min, 64min, 65min, or any range between any two of the aforementioned values.

[0052] In some embodiments of this application, step S100 includes: adding polyether polyol and modified epoxy resin into a microwave high-pressure reactor, stirring evenly at a second temperature to obtain a premixed solution.

[0053] Optionally, in step S100, the second temperature is 23℃~28℃, the stirring speed is 550r / min~600r / min, and the stirring time is 1h~1.2h. This setting allows the polyether polyol and modified epoxy resin to be mixed uniformly to obtain a homogeneous premix. For example, the second temperature can be 23℃, 24℃, 25℃, 26℃, 27℃, 28℃, or any range between two of the aforementioned values; the stirring speed can be 550r / min, 560r / min, 570r / min, 580r / min, 590r / min, 600r / min, or any range between two of the aforementioned values; and the stirring time can be 1h, 1.05h, 1.1h, 1.15h, 1.2h, or any range between two of the aforementioned values.

[0054] Optionally, in step S100, adding the polyether polyol and modified epoxy resin to the microwave high-pressure reactor includes adding the polyether polyol, modified epoxy resin, catalyst, antioxidant and deionized water to the microwave high-pressure reactor.

[0055] In some embodiments of this application, the foaming agent includes methyl formate, dimethyl carbonate, methyl lactate, and polyglycerol ricinoleate, and step S200 includes: S201. Add methyl formate to the premixed liquid, control the microwave high-pressure reactor to start dual-frequency microwave coupling heating, and perform gradient pressure increase and stirring; S202. Continue to add dimethyl carbonate, methyl lactate and polyglycerol ricinoleate, control the microwave high-pressure reactor to start dual-frequency microwave coupling heating, and perform gradient pressure increase and stirring.

[0056] Understandably, by employing dual-frequency microwave coupling heating, this application can achieve a more uniform reaction temperature, avoiding localized temperature differences and resulting in more even dispersion of the foaming agent. This, in turn, helps to reduce the density standard deviation and increase the filling rate. Furthermore, dual-frequency microwave coupling heating can shorten the curing time and reduce product energy consumption.

[0057] Optionally, in step S201, controlling the microwave high-pressure reactor to activate dual-frequency microwave coupled heating and perform gradient pressurization and stirring includes: controlling the microwave high-pressure reactor to activate two microwave frequencies of 2.4GHz~2.5GHz (e.g., 2.4GHz, 2.45GHz, or 2.5GHz) and 0.91GHz~0.92GHz (e.g., 0.91GHz, 0.915GHz, or 0.92GHz) for coupled heating, with a microwave power of 140W~160W (e.g., 140W, 145W, or 160W), and the pressure increasing from 0.75bar~0.85bar (e.g., 0.75bar, 0.8bar, or 0.85bar) at a rate of 0.15bar / min~0.25bar / min (e.g., 0.15bar / min, 0.2bar / min, or 0.25bar / min) to 1.45bar~1.55bar. Stir at a speed of 550 r / min to 600 r / min (e.g., 550 r / min, 560 r / min, 570 r / min, 580 r / min, 590 r / min or 600 r / min) and keep warm at 23℃ to 28℃ (e.g., 23℃, 24℃, 25℃, 26℃, 27℃ or 28℃) for 1 h to 1.2 h (e.g., 1 h, 1.05 h, 1.1 h, 1.15 h or 1.2 h).

[0058] Optionally, in step S202, controlling the microwave high-pressure reactor to activate dual-frequency microwave coupled heating and perform gradient pressurization and stirring includes: controlling the microwave high-pressure reactor to activate two microwave frequencies of 2.4GHz~2.5GHz (e.g., 2.4GHz, 2.45GHz, or 2.5GHz) and 0.91GHz~0.92GHz (e.g., 0.91GHz, 0.915GHz, or 0.92GHz) for coupled heating, with a microwave power of 170W~190W (e.g., 170W, 180W, or 190W), and the pressure increasing from 1.95bar~2.05bar (e.g., 1.95bar, 2.0bar, or 2.05bar) at a rate of 0.25bar / min~0.35bar / min (e.g., 0.25bar / min, 0.3bar / min, or 0.35bar / min) to 2.95bar~3. Stir at 0.05 bar (e.g., 2.95 bar, 3.0 bar, or 3.05 bar) and at a speed of 650 r / min to 700 r / min (e.g., 650 r / min, 660 r / min, 670 r / min, 680 r / min, 690 r / min, or 700 r / min) and keep warm at 23℃ to 28℃ (e.g., 23℃, 24℃, 25℃, 26℃, 27℃, or 28℃) for 0.5 h to 0.6 h (e.g., 0.5 h, 0.55 h, or 0.6 h).

[0059] In some embodiments of this application, step S300 includes: mixing the foaming mixture with isocyanate at a mass ratio of 1:(1.31~1.33) to obtain a polyurethane composition. Exemplarily, the mass ratio of the foaming mixture to isocyanate can be 1:1.31, 1:1.32, or 1.33, etc.

[0060] In some embodiments of this application, step S400 includes: injecting the polyurethane composition into a mold using a high-pressure foaming machine, and sequentially performing hot air curing, low-temperature setting, and room-temperature curing treatments to obtain polyurethane foam; wherein the temperature of the hot air curing treatment is 58°C to 62°C, the temperature of the low-temperature setting treatment is -8°C to -12°C, and the time of the room-temperature curing treatment is 23°C to 28°C.

[0061] For example, the temperature of the hot air curing treatment can be 58℃, 59℃, 60℃, 61℃ or 62℃, etc.; the temperature of the low temperature setting treatment can be -8℃, -9℃, -10℃, -11℃, -12℃ or any range between two of the aforementioned values, etc.; and the time of the room temperature curing treatment can be 23℃, 24℃, 25℃, 26℃, 27℃, 28℃ or any range between two of the aforementioned values, etc.

[0062] Optionally, the hot air curing treatment time is 2 hours to 2.2 hours, for example, 2 hours, 2.05 hours, 2.1 hours, 2.15 hours, 2.2 hours, or any range between two of the aforementioned values. Optionally, the low-temperature setting treatment time is 1 hour to 1.2 hours, for example, 1 hour, 1.05 hours, 1.1 hours, 1.15 hours, 1.2 hours, or any range between two of the aforementioned values. Optionally, the room temperature curing treatment time is 20 hours to 22 hours, for example, 20 hours, 20.5 hours, 21 hours, 21.5 hours, 22 hours, or any range between two of the aforementioned values.

[0063] Optionally, in step S400, injecting the polyurethane composition into the mold using a high-pressure foaming machine includes: injecting the polyurethane composition into the mold with a filler factor of 1.13 to 1.17 using a high-pressure foaming machine, and demolding after curing. For example, the filler factor can be 1.13, 1.14, 1.15, 1.16, 1.17, or a range between any two of the aforementioned values.

[0064] This application also provides a refrigeration device, which includes polyurethane foam, the specific structure of which is described in the above embodiments. Since this refrigeration device employs all the technical solutions of the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated upon here.

[0065] Optionally, the refrigeration equipment can be a refrigerator, freezer, biological sample transport box, or cold chain container, etc., and the polyurethane foam can be used as a heat insulation material for the refrigeration equipment.

[0066] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0067] The technical solutions and effects of this application will be described in detail below through specific embodiments and comparative examples. The following embodiments are only some embodiments of this application and are not intended to limit this application.

[0068] Example 1 This embodiment 1 provides a polyurethane foam, the preparation method of which includes the following steps: S101. By mass, 100 parts of polyether polyol, 12 parts of modified epoxy resin, 3.4 parts of catalyst, 0.45 parts of antioxidant, 2.8 parts of silicone oil (model AK8812), and 2.4 parts of deionized water are added to a microwave high-pressure reactor and stirred at 25°C and 500 r / min for 1.2 h to obtain a premixed solution. S102. Add 7 parts of methyl formate, control the microwave high-pressure reactor to turn on dual-frequency microwave coupling heating (power is 150W, the frequencies of the two microwaves are 2.45GHz and 0.915GHz respectively), and increase the pressure from 0.7bar to 1.5bar at a rate of 0.2bar / min, keep at 25℃ for 1h, and stir at a speed of 600r / min at the same time. S103. Add 3 parts of dimethyl carbonate, 1.5 parts of methyl lactate obtained from corn starch fermentation, and 0.4 parts of polyglycerol ricinoleate. Control the microwave power of the microwave high-pressure reactor to 180W, and gradually increase the pressure from 2.0 bar to 3.0 bar at a rate of 0.3 bar / min. Keep at 25°C for 0.5h, while stirring at a speed of 700 r / min to obtain a foamed mixture. S104. The foaming mixture and polymethyl polyphenyl polyisocyanate PM-200 are mixed at a mass ratio of 1:1.32, and then injected into a 6mm thin-walled mold (45℃) through a high-pressure foaming machine (160bar, 22℃) with a filler factor of 1.15. After curing for 3.5 minutes, the mixture is demolded and then subjected to hot air curing at 60℃ for 2 hours, low temperature setting at -20℃ for 2 hours, and room temperature curing at 25℃ for 22 hours in sequence to obtain polyurethane foam.

[0069] The preparation methods for some of the raw materials are as follows: Nano-SiO2 modified hydroxyl-terminated polybutadiene: 93-96 parts of hydroxyl-terminated polybutadiene were preheated to 50°C and stirred for 2.5 hours under vacuum of -0.090 MPa to remove water and bubbles; 0.2-0.5 parts of Span 80 (i.e., sorbitan monooleate) and 2-4 parts of dioctyl adipate were mixed, and nano-SiO2 (particle size 50 nm) was added and stirred evenly, and heated to 50°C to prepare a mixture; the dehydrated hydroxyl-terminated polybutadiene was stirred evenly with the mixture, and then a curing agent was added and stirred continuously at a constant temperature of 50°C to obtain a mixture; the mixture was vacuum cast (temperature 55°C, vacuum of -0.092 MPa) and then heated at 60°C for 12 hours to cure, thus obtaining nano-SiO2 modified hydroxyl-terminated polybutadiene.

[0070] Polyether polyol: Sucrose polyether polyol, hydroxyl-terminated polybutadiene and nano-SiO2 modified hydroxyl-terminated polybutadiene (particle size of 50nm) are mixed in a mass ratio of 30:8:5 to obtain polyether polyol.

[0071] Modified epoxy resin: γ-aminopropyltriethoxysilane is mixed with bisphenol A epoxy resin E-44 and reacted at 85°C for 30 min. Then, γ-glycidoxypropyltrimethoxysilane is added, and the reaction is continued for 60 min to obtain the modified epoxy resin. The mass ratio of bisphenol A epoxy resin E-44, γ-aminopropyltriethoxysilane, and γ-glycidoxypropyltrimethoxysilane is 100:3:2.

[0072] Catalyst: Pentamethyldiethylenetriamine, a diol solution of modified bis(dimethylaminoethyl) ether, bis(dimethylaminoethyl) ether, and 2-hydroxy-N,N,N-trimethyl-1-propylaminocarbamate were mixed in a mass ratio of 0.5:0.3:2.0:0.6 to obtain the catalyst.

[0073] Antioxidant: The antioxidant is obtained by mixing pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris(2,4-di-tert-butylphenyl)phosphite and vitamin E in a mass ratio of 0.25:0.12:0.08.

[0074] Example 2 Example 2 is basically the same as Example 1, except that: when preparing the modified epoxy resin, the mass ratio of bisphenol A epoxy resin E-44, γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane is 100:3.5:1.5.

[0075] Example 3 Example 3 is basically the same as Example 1, except that: when preparing the modified epoxy resin, the mass ratio of bisphenol A epoxy resin E-44, γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane is 100:2.5:2.5.

[0076] Example 4 Example 4 is basically the same as Example 1, except that when preparing the modified epoxy resin, bisphenol A epoxy resin E-44 is replaced with bisphenol A epoxy resin E-51.

[0077] Example 5 Example 5 is basically the same as Example 1, except that when preparing the modified epoxy resin, the bisphenol A epoxy resin E-44 is replaced with phenolic epoxy resin F-44.

[0078] Example 6 Example 6 is basically the same as Example 1, except that when preparing the modified epoxy resin, the bisphenol A epoxy resin E-44 is replaced with phenolic epoxy resin F-51.

[0079] Comparative Example 1 Comparative Example 1 is basically the same as Example 1, except that: In preparing the modified epoxy resin, γ-aminopropyltriethoxysilane is mixed with bisphenol A epoxy resin E-44 and reacted at 85°C for 90 min to obtain the modified epoxy resin. The mass ratio of bisphenol A epoxy resin E-44 to γ-aminopropyltriethoxysilane is 100:3. When preparing the antioxidant, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris(2,4-di-tert-butylphenyl) phosphite are mixed at a mass ratio of 0.25:0.12. In step S103, only 3 parts of dimethyl carbonate were added, and methyl lactate and polyglycerol ricinoleate were not added. The microwave was not turned on in either step S102 or step S103.

[0080] Comparative Example 2 Comparative Example 2 is basically the same as Example 1, except that: In step S101, the modified epoxy resin is replaced with bisphenol A epoxy resin E-44, and no antioxidant is added. In step S102, 7 parts of methyl formate are replaced with 8 parts of HFC-245fa (i.e., 1,1,1,3,3-pentafluoropropane), and in step S103, dimethyl carbonate, methyl lactate and polyglycerol ricinoleate are not added. The microwave was not turned on in either step S102 or step S103.

[0081] Comparative Example 3 Comparative Example 3 is basically the same as Example 1, except that: In preparing the modified epoxy resin, γ-glycidoxypropyltrimethoxysilane is mixed with bisphenol A epoxy resin E-44 and reacted at 85°C for 90 min to obtain the modified epoxy resin. The mass ratio of bisphenol A epoxy resin E-44 to γ-glycidoxypropyltrimethoxysilane is 100:2. When preparing the antioxidant, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris(2,4-di-tert-butylphenyl) phosphite are mixed at a mass ratio of 0.25:0.12. In step S103, only 3 parts of dimethyl carbonate were added, and methyl lactate and polyglycerol ricinoleate were not added. The microwave was not turned on in either step S102 or step S103.

[0082] Performance tests were conducted on the polyurethane foams of Examples 1-6 and Comparative Examples 1-3, and the test results are detailed in Table 1 below. The performance test items included: shrinkage rate at -60℃, thermal conductivity at 10℃, thermal conductivity at -60℃, interfacial bond strength, bio-based content, 2000h compressive strength retention rate, 6mm filler content, and density standard deviation.

[0083] The testing methods for each performance aspect are as follows: -60℃ Shrinkage rate: According to GB / T 8811-2008, the volume change rate of polyurethane foam at -60℃ for 24 hours was tested; Thermal conductivity: The thermal conductivity of polyurethane foam at 10°C and -60°C was tested using the hot wire method according to ISO 12939-01. Interfacial bond strength: The tensile bond strength between polyurethane foam and VIP board (aluminum-plastic film) was tested according to GB / T 7124-2021. Bio-based content: The bio-based content of polyurethane foam was tested using the radiocarbon method according to ASTM D6866-22. 2000h compressive strength retention rate: According to GB / T 8813-2022, the compressive strength retention rate of polyurethane foam at 60℃×95%RH×2000h was tested; 6mm fill rate: The polyurethane foam was scanned using CT scans to test the percentage of void area.

[0084] Density standard deviation: Take 5 pieces of polyurethane foam, test the density of the 5 pieces of polyurethane foam according to GB / T 6343-2009, and calculate the density standard deviation based on the density of these 5 pieces of polyurethane foam.

[0085] Table 1

[0086] As shown in Table 1, the thermal conductivity at 10℃ and -60℃ of the polyurethane foams in Examples 1-6 are all lower than those of the polyurethane foams in Comparative Examples 1-3. The shrinkage rate at -60℃ of the polyurethane foams in Examples 1-6 is also lower than that of the polyurethane foams in Comparative Examples 1-3. This indicates that the ultracrystic anti-embrittlement properties of the polyurethane foams in Examples 1-6 are all superior to those of the polyurethane foams in Comparative Examples 1-3. The differences in thermal conductivity and shrinkage rate at -60℃ may be due to the following: The modified epoxy resins used in Examples 1-6 are epoxy resins modified with γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane. The combination of γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane can form a gradient IPN structure, which is beneficial to reducing the thermal conductivity and shrinkage rate at -60℃ of polyurethane foam. In contrast, the modified epoxy resin used in Comparative Example 1 is an epoxy resin modified only with γ-aminopropyltriethoxysilane, Comparative Example 2 uses an unmodified epoxy resin, and Comparative Example 3 uses an epoxy resin modified only with γ-glycidoxypropyltrimethoxysilane.

[0087] The interfacial bonding strength of the polyurethane foams in Examples 1-6 is greater than that of the polyurethane foams in Comparative Examples 1-3, indicating that the polyurethane foams in Examples 1-6 have a lower risk of falling off after bonding with the substrate, which is beneficial to ensuring the thermal insulation effect and the structural stability of the refrigeration equipment.

[0088] The polyurethane foams in Examples 1-6 had a bio-based content between 35.6% and 40.5%, while the polyurethane foams in Comparative Examples 1-3 all had a bio-based content of 0%, indicating that the polyurethane foams in Examples 1-6 were more environmentally friendly than those in Comparative Examples 1-3. The difference in bio-based content may be due to the fact that the blowing agents used in Examples 1-6 included bio-based methyl lactate (obtained from corn starch fermentation) and polyglycerol ricinoleate, thus increasing the bio-based content of the system; while the blowing agents used in Comparative Examples 1-3 did not include methyl lactate and polyglycerol ricinoleate obtained from corn starch fermentation.

[0089] The 2000-hour compressive strength retention rates of the polyurethane foams in Examples 1-6 were all greater than those in Comparative Examples 1-3, indicating that the polyurethane foams in Examples 1-6 better meet the long-term requirements. The reason for the difference in compressive strength retention rates may be that the antioxidants used in Examples 1-6 included pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris(2,4-di-tert-butylphenyl) phosphite, and vitamin E. Vitamin E can supplement antioxidant activity and prolong the antioxidant cycle, which is beneficial to improving the 2000-hour compressive strength retention rate of the polyurethane foam. In contrast, Comparative Examples 1 and 3 used only pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris(2,4-di-tert-butylphenyl) phosphite as antioxidants, while Comparative Example 2 did not use any antioxidants.

[0090] The density standard deviation of the polyurethane foams in Examples 1-6 is smaller than that of the polyurethane foams in Comparative Examples 1-3, and the 6mm fill rate of the polyurethane foams in Examples 1-6 is larger than that of the polyurethane foams in Comparative Examples 1-3. The reason may be that Examples 1-6 adopted a process combining dual-frequency microwave coupled heating and gradient pressurization. Dual-frequency microwave coupled heating can make the reaction temperature more uniform, avoid local temperature differences, and make the foaming agent more uniformly dispersed, which is conducive to reducing the density standard deviation and increasing the fill rate. In contrast, Comparative Examples 1-3 only adopted the gradient pressurization process and did not adopt the dual-frequency microwave coupled heating process, resulting in local temperature differences and uneven dispersion of the foaming agent, which led to a larger density standard deviation and a lower fill rate.

[0091] The polyurethane composition, polyurethane foam, preparation method, and refrigeration equipment provided in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A polyurethane composition, characterized in that, The polyurethane composition comprises a polyether polyol, a modified epoxy resin, a foaming agent, and an isocyanate, wherein the modified epoxy resin is an epoxy resin modified with γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane.

2. The polyurethane composition according to claim 1, characterized in that, The polyurethane composition comprises, by parts by weight: 100 parts of the polyether polyol; The modified epoxy resin is 10 to 14 parts; The foaming agent is 10.3 to 11.9 parts; The isocyanate is 140 to 150 parts.

3. The polyurethane composition according to claim 1, characterized in that, The modified epoxy resin has a silicon content of 1.8% to 2.2%. And / or, the modified epoxy resin includes one or more of modified bisphenol A epoxy resin and modified phenolic epoxy resin.

4. The polyurethane composition according to claim 1, characterized in that, The polyether polyol includes sucrose polyether polyol, hydroxyl-terminated polybutadiene, and nano-SiO2 modified hydroxyl-terminated polybutadiene, wherein the mass ratio of the sucrose polyether polyol, the hydroxyl-terminated polybutadiene, and the nano-SiO2 modified hydroxyl-terminated polybutadiene is (28~32):(6~10):(3~7). And / or, the foaming agent comprises methyl formate, dimethyl carbonate, methyl lactate, and polyglycerol ricinoleate, wherein the mass ratio of methyl formate, dimethyl carbonate, methyl lactate, and polyglycerol ricinoleate is (6~7):(3~4):(1~2):(0.3~0.5); wherein the methyl lactate is prepared by fermentation of plant starch, and the plant starch includes one or more of corn starch, rice starch, and wheat starch; And / or, by weight, the polyurethane composition further comprises 2.75 to 4.05 parts of catalyst; the catalyst comprises pentamethyldiethylenetriamine, a diol solution of modified bis(dimethylaminoethyl) ether, bis(dimethylaminoethyl) ether, and 2-hydroxy-N,N,N-trimethyl-1-propylcarbamate, wherein the mass ratio of pentamethyldiethylenetriamine, the diol solution of modified bis(dimethylaminoethyl) ether, bis(dimethylaminoethyl) ether, and 2-hydroxy-N,N,N-trimethyl-1-propylcarbamate is (0.45~0.55):(0.25~0.35):(1.5~2.5):(0.55~0.65); And / or, by weight, the polyurethane composition further comprises 0.35 to 0.55 parts of an antioxidant, said antioxidant comprising pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris(2,4-di-tert-butylphenyl) phosphite, and vitamin E, wherein the weight ratio of said pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], said tris(2,4-di-tert-butylphenyl) phosphite, and said vitamin E is (0.2 to 0.3):(0.1 to 0.15):(0.05 to 0.1); And / or, by weight, the polyurethane composition further comprises 2.5 to 3.0 parts of silicone oil containing Si-C bonds; And / or, by weight, the polyurethane composition further comprises 2.2 to 2.6 parts of deionized water.

5. A polyurethane foam, characterized in that, It is prepared by foaming the polyurethane composition according to any one of claims 1 to 4.

6. The polyurethane foam according to claim 5, characterized in that, The polyurethane foam has a thermal conductivity of less than 22.3 mW / (mK) at 10℃, a thermal conductivity of less than 22.8 mW / (mK) at -60℃, and an interfacial bonding strength greater than 1.02 MPa.

7. A method for preparing polyurethane foam, characterized in that, The method for preparing the polyurethane foam includes the following steps: S100. Mix polyether polyol and modified epoxy resin to obtain a premixed liquid, wherein the modified epoxy resin is an epoxy resin modified with γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane. S200. The premixed liquid is mixed with a foaming agent to obtain a foamed mixture; S300. The foaming mixture is mixed with isocyanate to obtain a polyurethane composition; S400. The polyurethane composition is subjected to foaming treatment to obtain polyurethane foam.

8. The method for preparing polyurethane foam according to claim 7, characterized in that, The modified epoxy resin is prepared by the following method: First, γ-aminopropyltriethoxysilane is mixed with epoxy resin and reacted at a first temperature for a first time. Then, γ-glycidoxypropyltrimethoxysilane is added and reacted at the first temperature for a second time to obtain modified epoxy resin.

9. The method for preparing polyurethane foam according to claim 8, characterized in that, The mass ratio of the epoxy resin, the γ-aminopropyltriethoxysilane, and the γ-glycidoxypropyltrimethoxysilane is 100:(2.5~3.5):(1.5~2.5). And / or, the first temperature is 80℃~90℃, the first time is 30min~35min, and the second time is 60min~65min; And / or, the epoxy resin includes one or more of bisphenol A epoxy resin and phenolic epoxy resin.

10. The method for preparing polyurethane foam according to claim 7, characterized in that, Step S100 includes: adding polyether polyol and modified epoxy resin into a microwave high-pressure reactor, stirring evenly at a second temperature to obtain a premixed solution; The foaming agent includes methyl formate, dimethyl carbonate, methyl lactate, and polyglycerol ricinoleate, and step S200 includes: S201. Add methyl formate to the premixed liquid, control the microwave high-pressure reactor to start dual-frequency microwave coupling heating, and perform gradient pressure increase and stirring; S202. Continue to add dimethyl carbonate, methyl lactate and polyglycerol ricinoleate, control the microwave high-pressure reactor to start dual-frequency microwave coupling heating, and perform gradient pressure increase and stirring.

11. The method for preparing polyurethane foam according to claim 10, characterized in that, In step S100, the second temperature is 23℃~28℃, the stirring speed is 550r / min~600r / min, and the stirring time is 1h~1.2h; And / or, the addition of polyether polyol and modified epoxy resin to the microwave high-pressure reactor includes: adding polyether polyol, modified epoxy resin, catalyst, antioxidant and deionized water to the microwave high-pressure reactor.

12. The method for preparing polyurethane foam according to claim 10, characterized in that, In step S201, controlling the microwave high-pressure reactor to activate dual-frequency microwave coupling heating and perform gradient pressure increase and stirring includes: controlling the microwave high-pressure reactor to activate two microwaves with frequencies of 2.4GHz~2.5GHz and 0.91GHz~0.92GHz respectively for coupled heating, with a microwave power of 140W~160W, the pressure increasing from 0.75bar~0.85bar at a rate of 0.15bar / min~0.25bar / min to 1.45bar~1.55bar, stirring at a speed of 550r / min~600r / min, and maintaining the temperature at 23℃~28℃ for 1h~1.2h; In step S202, controlling the microwave high-pressure reactor to activate dual-frequency microwave coupling heating and perform gradient pressure increase and stirring includes: controlling the microwave high-pressure reactor to activate two microwaves with frequencies of 2.4GHz~2.5GHz and 0.91GHz~0.92GHz respectively for coupled heating, with a microwave power of 170W~190W, increasing the pressure from 1.95bar~2.05bar at a rate of 0.25bar / min~0.35bar / min to 2.95bar~3.05bar, stirring at a speed of 650r / min~700r / min, and maintaining the temperature at 23℃~28℃ for 0.5h~0.6h.

13. The method for preparing polyurethane foam according to claim 7, characterized in that, Step S400 includes: injecting the polyurethane composition into a mold through a high-pressure foaming machine, and sequentially performing hot air curing treatment, low-temperature shaping treatment and room temperature curing treatment to obtain polyurethane foam; The hot air curing treatment is performed at a temperature of 58℃ to 62℃, the low temperature setting treatment is performed at a temperature of -8℃ to -12℃, and the room temperature curing treatment is performed at a time of 23℃ to 28℃.

14. The method for preparing polyurethane foam according to claim 13, characterized in that, The hot air curing process takes 2 hours to 2.2 hours. And / or, the low-temperature setting treatment time is 1h~1.2h; And / or, the room temperature aging process takes 20h to 22h.

15. A refrigeration device, characterized in that, The refrigeration device includes the polyurethane foam according to any one of claims 5 to 6, or the refrigeration device includes polyurethane foam prepared by the method for preparing polyurethane foam according to any one of claims 7 to 14.

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