A polyurethane composition, its preparation method and application

Abstract

This invention provides a polyurethane composition comprising the following raw materials: Component A: 70-90 parts polyether polyol, 10-30 parts polyester polyol, 5-10 parts chain extender, 2.5-4.5 parts catalyst, 2-5 parts foam leveling agent, and 15.5-36 parts blowing agent; Component B: 145-147 parts isocyanate; the chain extender includes a first chain extender and a second chain extender, wherein the first chain extender is a compound shown in structural formula 1 and the second chain extender is a compound shown in structural formula 2. The polyurethane composition provided by this application has strong compressive strength and hydrophobicity, and good heat resistance.

Description

Technical Field

[0001] This invention relates to the field of polyurethane preparation technology, and in particular to a polyurethane composition, its preparation method, and its application. Background Technology

[0002] Polyurethane insulation material is a high-performance synthetic material with advantages such as high specific strength and low thermal conductivity, and is mainly used as a thermal insulation material. Polyurethane, also known as urethane, is a polymer compound characterized by numerous repeating urethane groups in its main chain. Polyurethane is obtained through the stepwise addition reaction of polyisocyanates and polyhydroxy compounds. By changing the number and type of functional groups, polyurethane materials with different properties and forms can be obtained.

[0003] Polyurethane is typically prepared by polymerization of polyether diols or polyester diols with isocyanates and other raw materials. Polyurethane insulation materials prepared from polyether diols exhibit hydrolysis resistance and low water absorption, but their compressive strength is low. Polyurethane insulation materials prepared from polyester diols have high compressive strength, but are prone to hydrolysis and have high water absorption. To address these issues, polyurethane is prepared using polyether diols, polyester diols, and isocyanates as raw materials, with the addition of chain extenders. Commonly used chain extenders include fluorinated chain extenders. However, the use of fluorinated chain extenders, due to the low surface energy and strong hydrophobicity of the fluorocarbon chains, results in weak molecular-level interactions with other components in the polyurethane, such as polyether polyols and polyester polyols. This leads to poor compatibility when the fluorinated chain extender reacts with other components, affecting cell formation and reducing mechanical properties. Consequently, the resulting polyurethane composition cannot simultaneously achieve high compressive strength, low water absorption, and good heat resistance. Summary of the Invention

[0004] To address the problem that existing polyurethane preparations using polyester diols, polyether diols, and isocyanates as raw materials, with the addition of fluorinated chain extenders, result in reduced mechanical properties and an inability to achieve a balance of high compressive strength, low water absorption, and good heat resistance, this application provides a polyurethane composition, its preparation method, and its application.

[0005] In a first aspect, the present invention provides a polyurethane composition comprising the following raw materials:

[0006] Component A: 70-90 parts polyether polyol, 10-30 parts polyester polyol, 5-10 parts chain extender, 2.5-4.5 parts catalyst, 2-5 parts foam stabilizer, 15.5-36 parts foaming agent;

[0007] Component B: 145-147 parts isocyanate;

[0008] The chain extender includes a first chain extender and a second chain extender, wherein the first chain extender is a compound shown in structural formula 1:

[0009]

[0010] R1, R2, R3, R4, and R5 are each independently selected from at least one of an alkyl group in which at least one hydrogen atom is substituted by fluorine, a hydroxyl-terminated alkyl chain, or an alkyl group, and at least one of R3 and R4 is selected from a hydroxyl-terminated alkyl chain.

[0011] The second chain extender is the compound shown in structural formula 2:

[0012]

[0013] Among them, R 11 R 12 R 13 R 14 R 15 R 16 R 17 R 18 R 21 R 22 R 23 R 24 R 25 R 26 R 27 R 28 Each is independently selected from alkyl groups;

[0014] R6 and R7 are selected from at least one of hydroxyl-terminated alkyl chains and alkyl groups, and at least one of R6 and R7 is selected from a hydroxyl-terminated alkyl chain.

[0015] Preferably, R1, R2, R3, R4, and R5 are each independently selected from at least one of C3-C15 alkyl groups in which at least one hydrogen atom is substituted by fluorine, a hydroxyl-terminated C1-C5 alkyl chain, and a C1-C5 alkyl group, and at least one of R3 and R4 is selected from a hydroxyl-terminated C1-C5 alkyl chain.

[0016] R 11 R 12 R 13 R 14 R 15 R 16 R 17 R 18 R 21 R 22 R 23 R 24 R 25 R 26 R 27 R28 Selected from C1~C5 alkyl groups;

[0017] R6 and R7 are selected from at least one of hydroxyl-terminated C1-C5 alkyl chains and C1-C5 alkyl groups, and at least one of R6 and R7 is selected from a hydroxyl-terminated C1-C5 alkyl chain.

[0018] Preferably, the mass ratio of the first chain extender to the second chain extender is 1:(0.1~0.3).

[0019] Preferably, R5 is selected from C6-C12 perfluoroalkyl groups.

[0020] Preferably, the polyether polyol includes polyether polyol I with a hydroxyl value of 440~460 mgKOH / g and polyether polyol II with a hydroxyl value of 745~775 mgKOH / g;

[0021] In the polyurethane composition, the polyether polyol I is 40-50 parts and the polyether polyol II is 30-40 parts; the mass ratio of the polyether polyol I, the polyether polyol II and the polyester polyol is (1.2-5):(1-4):1.

[0022] And / or, the hydroxyl value of the polyester polyol is 230~250 mgKOH / g.

[0023] Preferably, the catalyst includes at least one of organic salt catalysts and tertiary amine catalysts;

[0024] The organic salt catalyst includes one or more of the following: dibutyltin dilaurate, potassium acetate, potassium isooctanoate, potassium oleate, stannous octoate, and dibutyltin dilaurate acetate;

[0025] The tertiary amine catalysts include one or more of triethylenediamine, triethylenediamine, dimethylcyclohexylamine, triethanolamine, triethylamine, trimethylbenzylamine, and dimethylethanolamine;

[0026] The foam stabilizer includes one or more of the following: silicone oil, bis-(γ-triethoxysilylpropyl)tetrasulfide, γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, vinyltriethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane.

[0027] The foaming agent includes one or both of water and dichlorofluoroethane.

[0028] The isocyanate includes one or more of diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate, dicyclohexylmethane diisocyanate, diphenylmethane-4,4'-diisocyanate, phenylmethylene diisocyanate, naphthalene-1,5-diisocyanate, terephthalic diisocyanate, and tetramethylphenylmethylene diisocyanate.

[0029] Secondly, this application provides a method for preparing the polyurethane composition described above, comprising the following steps:

[0030] Prepare component A and component B according to the parts by weight;

[0031] The polyurethane composition is obtained by mixing the A component and the B component evenly.

[0032] Preferably, the preparation method of the first chain extender includes the following steps:

[0033] Under a protective atmosphere, compound 1 and compound 2 are mixed evenly with a first solvent, and a first heating reaction is carried out to obtain a first mixture. The first mixture is then extracted and distilled under reduced pressure to obtain the first chain extender.

[0034] The reaction temperature in the first heating reaction is 60~80℃, and the reaction time is 12~24h;

[0035] Compound 1 is the compound shown in structural formula 3, and compound 2 is the compound shown in structural formula 4.

[0036] ,

[0037] Wherein, R3 and R4 are each independently selected from alkyl and hydroxyl-terminated alkyl chains; and at least one of R3 and R4 is selected from a hydroxyl-terminated alkyl chain; R2' is selected from an alkenyl group; R1 is selected from an alkyl group; and R5 is selected from an alkyl group in which at least one hydrogen atom is substituted by fluorine.

[0038] The molar ratio of compound 1 to compound 2 is 1:(1.1~1.3).

[0039] The first solvent includes one or more of alcohol solvents, ethyl acetate, N-methylpyrrolidone, and dipropylene glycol dimethyl ether.

[0040] Preferably, the preparation method of the second chain extender includes the following steps:

[0041] Under a protective atmosphere, compounds 3 and 4 are mixed evenly with a second solvent, and a second heating reaction is carried out to obtain a second mixture. The second mixture is then extracted and distilled under reduced pressure to obtain the second chain extender.

[0042] The reaction temperature in the second heating reaction is 60~80℃, and the reaction time is 12~24h;

[0043] Compound 3 is the compound shown in structural formula 5, and compound 4 is the compound shown in structural formula 6.

[0044] ,

[0045] R6 and R7 are each independently selected from alkyl or hydroxyl-terminated alkyl chains; and at least one of R6 and R7 is selected from a hydroxyl-terminated alkyl chain; R2 is selected from an alkenyl group; R1 is selected from an alkyl group; and R5 is selected from an alkyl group in which at least one hydrogen atom is substituted by fluorine.

[0046] R 11 R 12 R 13 R 14 R 15 R 16 R 17 R 18 Each is independently selected from alkyl groups;

[0047] R 21 ', R 22 ', R 23 ', R 24 ', R 25 ', R 26 ', R 27 ', R 28 Each is independently selected from alkenyl groups;

[0048] The molar ratio of compound 3 to compound 4 is 1:(8.2~8.5).

[0049] The second solvent includes one or more of alcohol solvents, ethyl acetate, N-methylpyrrolidone, and dipropylene glycol dimethyl ether.

[0050] Thirdly, this application provides an application of the polyurethane composition described above or the polyurethane composition prepared by the method described above in thermal insulation materials.

[0051] The polyurethane composition provided in this application has the following effects:

[0052] 1) Adding 70-90 parts of polyether polyol and 10-30 parts of polyester polyol is beneficial to obtaining a polyurethane composition that has the characteristics of compressive strength, low water absorption and heat resistance.

[0053] 2) The addition of the first and second chain extenders increases the compatibility of the system. The two chain extenders work synergistically to react with the isocyanate groups in the polyurethane prepolymer. The first and second chain extenders are introduced into the polyurethane molecular chain, which elongates the molecular chain and helps to improve the strength of the polyurethane cell. This makes the cells in the polyurethane composition less susceptible to compression by external influences, thus optimizing the best hydrophobic properties. The polyurethane composition has strong hydrophobicity and can maintain a low water absorption rate even in humid environments.

[0054] 3) The polyurethane composition provided in this application has strong compressive strength, good hydrophobicity, and can effectively maintain continuous thermal insulation function. The polyurethane composition has low thermal conductivity and good heat resistance. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0056] To illustrate the technical solution of the present invention, specific embodiments are described below.

[0057] In a first aspect, in one embodiment of the present invention, a polyurethane composition is provided, comprising the following raw materials:

[0058] Component A: 70-90 parts polyether polyol, 10-30 parts polyester polyol, 5-10 parts chain extender, 2.5-4.5 parts catalyst, 2-5 parts foam stabilizer, 15.5-36 parts foaming agent;

[0059] Component B: 145-147 parts isocyanate;

[0060] The chain extender includes a first chain extender and a second chain extender, wherein the first chain extender is a compound shown in structural formula 1:

[0061]

[0062] R1, R2, R3, R4, and R5 are each independently selected from at least one of an alkyl group in which at least one hydrogen atom is substituted by fluorine, a hydroxyl-terminated alkyl chain, or an alkyl group, and at least one of R3 and R4 is selected from a hydroxyl-terminated alkyl chain.

[0063] The second chain extender is the compound shown in structural formula 2:

[0064]

[0065] Among them, R 11 R 12 R 13 R14 R 15 R 16 R 17 R 18 R 21 R 22 R 23 R 24 R 25 R 26 R 27 R 28 Each is independently selected from alkyl groups;

[0066] R6 and R7 are selected from at least one of hydroxyl-terminated alkyl chains and alkyl groups, and at least one of R6 and R7 is selected from a hydroxyl-terminated alkyl chain.

[0067] Specifically, alkyl groups include straight-chain alkyl groups or branched alkyl groups, such as straight-chain alkyl groups like methyl, ethyl, and propyl, or branched alkyl groups like isobutyl and isopropyl.

[0068] At least one of R3 and R4 is selected from a hydroxyl-terminated alkyl chain, meaning that R3 or R4 is selected from a hydroxyl-terminated alkyl chain, or both R3 and R4 are selected from hydroxyl-terminated alkyl chains.

[0069] R 11 R 12 R 13 R 14 R 15 R 16 R 17 R 18 R 21 R 22 R 23 R 24 R 25 R 26 R 27 R 28 Each is independently selected from alkyl groups, which can be understood as R 11 R 12 R 13 R 14 R 15 R 16 R 17 R 18 R 21 R 22 R 23 R 24 R 25 R 26 R 27 R 28 The selected groups can be the same or different.

[0070] At least one of R6 and R7 is selected from a hydroxyl-terminated alkyl chain, meaning that R6 or R7 is selected from a hydroxyl-terminated alkyl chain, or both R6 and R7 are selected from hydroxyl-terminated alkyl chains.

[0071] Specifically, polyurethane insulation materials prepared by reacting polyether polyols and isocyanates alone contain polyether segments and have low water absorption, but also low compressive strength. Polyurethane insulation materials prepared by reacting polyester polyols and isocyanates alone have high compressive strength, but are prone to hydrolysis and have high water absorption. The polyurethane composition provided in this application adds 70-90 parts of polyether polyol and 10-30 parts of polyester polyol. The combination of polyether polyol and polyester polyol is beneficial to obtaining a polyurethane composition that has the characteristics of compressive strength, low water absorption, and heat resistance.

[0072] The first chain extender is a fluorinated chain extender. Due to the small atomic radius and high electronegativity of fluorine, and the high bond energy of the carbon-fluorine bond, the formed pores are more difficult to compress. The fluorocarbon chain can also significantly reduce the surface tension of water. By adjusting the proportion of the chain extender, the polyurethane polymer can have a carbon-fluorine enriched surface layer, which has strong hydrophobicity. However, the inventors found that when the first chain extender is added alone during the preparation of the polyurethane composition, the first chain extender, due to its low surface energy and strong hydrophobicity caused by the fluorocarbon chain, has weak molecular-level interaction with other components in the polyurethane, such as polyether polyols, polyester polyols, and isocyanates. This results in poor compatibility between the first chain extender and other components, affecting the formation of pores and leading to a decrease in the mechanical properties of the polyurethane composition. The compound shown in structural formula 2 has a unique cage-like organosilicon framework structure. The cage-like structure composed of silicon-oxygen bonds can effectively block water vapor molecules and form a dense barrier layer on the surface of the polyurethane composition. If a second chain extender is added alone, the unique cage-like structure with a rigid core and hydrophobic region will make the polyurethane molecules too rigid, reducing the mechanical properties of the polyurethane composition.

[0073] To address the aforementioned problems, the inventors discovered that adding a first chain extender and a second chain extender during the preparation of the polyurethane composition, with similar structures, and the second chain extender having a main structure containing an organosilicon structure and flexible segments, exhibits good compatibility with polyurethane. Synergistically, the second chain extender can reduce its rigidity. The second chain extender contains the same amino alcohol segments as the first chain extender, which can improve the compatibility of the first chain extender. Therefore, the system of the second and first chain extenders can increase the compatibility of the system. The synergistic effect of the first and second chain extenders allows them to leverage their respective advantages, improving the strength of the polyurethane cells, optimizing hydrophobic properties, and resulting in a polyurethane composition with strong compressive strength and hydrophobicity. Simultaneously, it improves the heat resistance of the polyurethane composition, making it less prone to decomposition or deterioration at high temperatures.

[0074] The polyurethane composition provided in this application has the following effects:

[0075] 1) Adding 70-90 parts of polyether polyol and 10-30 parts of polyester polyol is beneficial to obtaining a polyurethane composition that has the characteristics of compressive strength, low water absorption and heat resistance.

[0076] 2) The addition of the first and second chain extenders increases the compatibility of the system. The two chain extenders work synergistically to react with the isocyanate groups in the polyurethane prepolymer. The first and second chain extenders are introduced into the polyurethane molecular chain, which elongates the molecular chain and helps to improve the strength of the polyurethane cell. This makes the cells in the polyurethane composition less susceptible to compression by external influences, thus optimizing the best hydrophobic properties. The polyurethane composition has strong hydrophobicity and can maintain a low water absorption rate even in humid environments.

[0077] 3) The polyurethane composition provided in this application has strong compressive strength, good hydrophobicity, and can effectively maintain continuous thermal insulation function. The polyurethane composition has low thermal conductivity and good heat resistance.

[0078] In some embodiments, R1, R2, R3, R4, and R5 are each independently selected from at least one of C3-C15 alkyl groups in which at least one hydrogen atom is substituted by fluorine, a hydroxyl-terminated C1-C5 alkyl chain, and a C1-C5 alkyl group, and at least one of R3 and R4 is selected from a hydroxyl-terminated C1-C5 alkyl chain.

[0079] Specifically, the hydroxyl-terminated C1~C5 alkyl chain can be a -CH2CH(CH3)OH group, -CH2CH2CH2OH, -CH2CH(CH2CH3)CH2OH, etc.

[0080] Both the first and second chain extenders contain -OH and -NH- groups. The first and second chain extenders work synergistically to increase the system's compatibility, allowing both to react well with the isocyanate groups. This consumes some of the isocyanate, shifting the reaction equilibrium between the polyether polyol, polyester polyol, and isocyanate, and promoting the reaction towards the formation of longer molecular chains in polyurethane. By adjusting the molecular chain structure, the entanglement and interaction forces between polyurethane molecular chains are enhanced, thereby improving the mechanical properties of the polyurethane composition.

[0081] In some preferred embodiments, R3 and R4 are selected from hydroxyl-terminated C2-C4 alkyl chains, R2 is selected from C2-C4 alkyl groups, R1 is selected from C2-C4 alkyl groups, and R5 is selected from C5-C10 alkyl groups in which at least one hydrogen atom is replaced by fluorine.

[0082] R1, R2, R3, R4, and R5 in the first chain extender are each selected from the above-mentioned groups. They contain more hydroxyl groups, which can react more hydroxyl groups with isocyanate groups. At the same time, the overall molecular structure of the chain extender is relatively compact, the intermolecular distance is relatively small, and the interaction force is enhanced. In synergy with the second chain extender, it helps to improve the hardness of the polyurethane composition and improve the mechanical properties.

[0083] In some preferred embodiments, R5 is selected from C6-C12 perfluoroalkyl groups, which contain more fluorine, thus improving the hydrophobic properties of the polyurethane composition.

[0084] In some embodiments, R 11 R 12 R 13 R 14 R 15 R 16 R 17 R 18 R 21 R 22 R 23 R 24 R 25 R 26 R 27 R 28 R6 and R7 are selected from C1-C5 alkyl groups; R7 and R8 are selected from at least one of hydroxyl-terminated C1-C5 alkyl chains and C1-C5 alkyl groups. Specifically, the second chain extender obtained by selecting the above groups has a shorter molecular chain and stronger intermolecular forces with the molecular chain of the first chain extender, which is more conducive to increasing the compatibility of the system, increasing the hardness of the polyurethane composition, and improving the mechanical properties of the polyurethane composition.

[0085] In some preferred embodiments, R6 and R7 are selected from hydroxyl-terminated C1-C5 alkyl chains.

[0086] Specifically, R6 and R7 are both selected from hydroxyl-terminated C1~C5 alkyl chains. The second chain extender contains more hydroxyl groups, which increases the compatibility of the reaction system and enables it to react with more isocyanate groups, thus linking more polyurethane prepolymer molecules together. It works synergistically with the first chain extender to improve the mechanical properties of the polyurethane composition.

[0087] In some embodiments, the mass ratio of the first chain extender to the second chain extender is 1:(0.1~0.3).

[0088] Specifically, the mass ratio of the first chain extender to the second chain extender is in the range of 1:(0.1~0.3). The amount of the second chain extender used is small, which reduces the rigidity of the polyurethane composition and can also increase the compatibility of the system. This is conducive to the first and second chain extenders playing a better synergistic role, improving the mechanical properties and hydrophobic properties of the polyurethane composition, improving the heat resistance of the polyurethane composition, and making the polyurethane composition less prone to decomposition or deterioration at high temperatures.

[0089] Specifically, the mass ratio of the first chain extender to the second chain extender can be 1:0.1, 1:0.15, 1:0.18, 1:0.2, 1:0.25, 1:0.3, etc., as long as the mass ratio of the first chain extender to the second chain extender is within the range of 1:(0.1~0.3).

[0090] If the mass ratio of the first chain extender to the second chain extender in the polyurethane composition is less than 1:(0.1~0.3), the content of the second chain extender is too high, resulting in high rigidity of the polyurethane and reduced mechanical properties. If the mass ratio of the first chain extender to the second chain extender is higher than 1:(0.1~0.3), the content of the second chain extender is low, resulting in poor compatibility between the first chain extender and components such as isocyanate, affecting cell formation and reducing the compatibility of the polyurethane composition.

[0091] In some embodiments, the polyether polyol includes polyether polyol I with a hydroxyl value of 440~460 mgKOH / g and polyether polyol II with a hydroxyl value of 745~775 mgKOH / g;

[0092] In the polyurethane composition, the polyether polyol I is 40-50 parts and the polyether polyol II is 30-40 parts; the mass ratio of the polyether polyol I, the polyether polyol II and the polyester polyol is (1.2-5):(1-4):1.

[0093] Specifically, in the polyurethane composition, the polyether polyol I comprises 40-50 parts, and the polyether polyol II comprises 30-40 parts. In the polyurethane composition, the mass ratio of polyether polyol I, polyether polyol II, and polyester polyol is (1.2-5):(1-4):1, which can better control the reaction rate and the molecular weight of the generated polyurethane, adjust the balance of hardness and flexibility of the polyurethane composition, and ensure good water resistance and heat resistance.

[0094] In some embodiments, the hydroxyl value of the polyester polyol is 230~250 mgKOH / g.

[0095] Similarly, limiting the hydroxyl value of the polyester polyol to the range of 230~250 mgKOH / g is beneficial for regulating the reaction rate, controlling the molecular weight of the generated polyurethane, and ensuring that the obtained polyurethane composition has the characteristics of compressive strength, low water absorption and heat resistance.

[0096] In some embodiments, the catalyst includes at least one of an organic salt catalyst and a tertiary amine catalyst;

[0097] The organic salt catalyst includes one or more of the following: dibutyltin dilaurate, potassium acetate, potassium isooctanoate, potassium oleate, stannous octoate, and dibutyltin dilaurate acetate;

[0098] The tertiary amine catalysts include one or more of triethylenediamine, triethylenediamine, dimethylcyclohexylamine, triethanolamine, triethylamine, trimethylbenzylamine, and dimethylethanolamine.

[0099] The catalyst is selected from at least one of organic salt catalysts and tertiary amine catalysts, which is beneficial to increasing the reaction rate.

[0100] The foaming agent includes one or more of silicone oil, bis-(γ-triethoxysilylpropyl)tetrasulfide, γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, vinyltriethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane.

[0101] Specifically, the foam leveling agent is selected from at least one of the above types, which helps to improve the cell structure, making the cells more uniform and fine, and improving foam stability.

[0102] In some embodiments, the foaming agent comprises one or both of water and dichlorofluoroethane.

[0103] Specifically, the foaming agent is selected from at least one of the above types. In the preparation of the polyurethane composition, the foaming agent generates gas, and the generated gas forms cells in the polyurethane.

[0104] In some embodiments, the isocyanate includes one or more of diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate, dicyclohexylmethane diisocyanate, diphenylmethane-4,4'-diisocyanate, phenylmethylene diisocyanate, naphthalene-1,5-diisocyanate, terephthalic diisocyanate, and tetramethylphenylmethylene diisocyanate.

[0105] Secondly, this application provides a method for preparing the polyurethane composition described above, comprising the following steps:

[0106] Prepare component A and component B according to the parts by weight;

[0107] The polyurethane composition is obtained by mixing the A component and the B component evenly.

[0108] The polyurethane composition provided in this application is obtained by directly mixing component A and component B. The preparation method is simple. The resulting polyurethane composition has strong compressive strength and hydrophobicity, and can effectively maintain continuous thermal insulation function. The polyurethane composition has low thermal conductivity and good heat resistance.

[0109] The specific preparation method of the polyurethane composition is as follows:

[0110] Prepare components A and B according to their weight proportions;

[0111] Component A: 70-90 parts polyether polyol, 10-30 parts polyester polyol, 5-10 parts chain extender, 2.5-4.5 parts catalyst, 2-5 parts foam leveling agent, and 15.5-36 parts foaming agent; the chain extender includes a first chain extender and a second chain extender.

[0112] Component B: 145-147 parts isocyanate;

[0113] The polyurethane composition is obtained by mixing component A and component B evenly.

[0114] Specifically, in the polyurethane composition, the amount of polyether polyol can be 70 parts, 72 parts, 75 parts, 78 parts, 80 parts, 83 parts, 85 parts, 87 parts, 90 parts, etc., as long as the amount of polyether polyol is within the range of 70 to 90 parts. In the polyurethane composition, the amount of polyester polyol can be 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, 20 parts, 23 parts, 26 parts, 29 parts, 30 parts, etc., as long as the amount of polyester polyol is within the range of 10 to 30 parts. In the polyurethane composition, the amount of chain extender can be 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, etc., as long as the amount of chain extender is within the range of 10 to 30 parts. In the polyurethane composition, the amount of catalyst can be 2.5 parts, 2.8 parts, 3.0 parts, 3.2 parts, 3.5 parts, 3.7 parts, 3.9 parts, 4.0 parts, 4.2 parts, 4.5 parts, etc., as long as the amount of catalyst is in the range of 2.5 to 4.5 parts.

[0115] In the polyurethane composition, the isocyanate content is 145, 146, 147, etc.

[0116] In polyurethane compositions, the amount of foam leveling agent can be 2 parts, 2.3 parts, 2.5 parts, 2.8 parts, 3.0 parts, 3.3 parts, 3.5 parts, 4.0 parts, 4.3 parts, 4.5 parts, 5.0 parts, etc., as long as the amount of foam leveling agent is within the range of 2 to 5 parts. In polyurethane compositions, the amount of foaming agent can be 15.5, 17, 17.5, 18, 19, 20, 23, 25, 26, 28, 30, 32, 35, 36 parts, etc., as long as the amount of foaming agent is within the range of 15.5 to 36 parts.

[0117] In some embodiments, the preparation method of the first chain extender includes the following steps:

[0118] Under a protective atmosphere, compound 1 and compound 2 are mixed evenly with a first solvent, and a first heating reaction is carried out to obtain a first mixture. The first mixture is then extracted and distilled under reduced pressure to obtain the first chain extender.

[0119] Compound 1 is the compound shown in structural formula 3, and compound 2 is the compound shown in structural formula 4.

[0120] ,

[0121] R3 and R4 are each independently selected from alkyl chains with alkyl or hydroxyl-terminated ends; and at least one of R3 and R4 is selected from alkyl chains with hydroxyl-terminated ends; R2' is selected from alkenyl; R1 is selected from alkyl; and R5 is selected from alkyl groups in which at least one hydrogen atom is replaced by fluorine.

[0122] Specifically, a protective atmosphere refers to filling a vacuum with a protective gas. The protective gas includes one of the rare gases and nitrogen. Rare gases include helium, argon, etc.

[0123] Compound 1 is the compound shown in structural formula 3, and compound 2 is the compound shown in structural formula 4. In the compound shown in structural formula 4, R2 is selected from an alkenyl group and contains a carbon-carbon double bond. When compound 1 and compound 2 react, the carbon-carbon double bond reacts with the amino group in compound 1 to generate the compound shown in structural formula 1.

[0124] After the first heating reaction is completed, a first mixture is obtained. The first mixture is extracted with distilled water or deionized water to remove unreacted reactant compound 1 and the first solvent. The extraction is performed at least once, preferably more than once. After extraction, the mixture is distilled under reduced pressure to remove excess compound 2 and water, thus obtaining the first chain extender.

[0125] In some embodiments, the reaction temperature in the first heating reaction is 60~80°C, and the reaction time is 12~24h.

[0126] Specifically, the reaction temperature in the first heating reaction can be 60℃, 62℃, 65℃, 67℃, 68℃, 70℃, 73℃, 75℃, 77℃, 79℃, 80℃, etc., as long as the reaction temperature of the first heating reaction is within the range of 60℃ to 80℃. If the reaction temperature of the first heating reaction is below 60℃, compound 1 and compound 2 cannot react effectively; if the reaction temperature of the first heating reaction is above 80℃, the reaction temperature is too high, and the reaction byproducts increase.

[0127] In some embodiments, the molar ratio of compound 1 to compound 2 is 1:(1.1~1.3).

[0128] Specifically, when the molar ratio of compound 1 to compound 2 is within the range of 1:(1.1~1.3), the compound shown in structural formula 1 can be generated at a lower cost.

[0129] In some embodiments, the first solvent includes one or more of alcohol solvents, ethyl acetate, N-methylpyrrolidone, and dipropylene glycol dimethyl ether.

[0130] Alcohol solvents include methanol, ethanol, isopropanol, etc.

[0131] In some preferred embodiments, compound 1 is diisopropanolamine and compound 2 is perfluorooctyl ethyl acrylate.

[0132] It should be noted that compound 1 and compound 2 were mixed evenly under a protective atmosphere; and the reaction was carried out under a protective atmosphere and heated to a temperature of 60~80℃.

[0133] In some embodiments, the preparation method of the second chain extender includes the following steps:

[0134] Under a protective atmosphere, compounds 3 and 4 are mixed evenly with a second solvent, and a second heating reaction is carried out to obtain a second mixture. The second mixture is then extracted and distilled under reduced pressure to obtain the second chain extender.

[0135] Compound 3 is the compound shown in structural formula 5, and compound 4 is the compound shown in structural formula 6.

[0136] ,

[0137] R6 and R7 are each independently selected from alkyl or hydroxyl-terminated alkyl chains; and at least one of R6 and R7 is selected from a hydroxyl-terminated alkyl chain; R2 is selected from an alkenyl group; R1 is selected from an alkyl group; and R5 is selected from an alkyl group in which at least one hydrogen atom is substituted by fluorine.

[0138] R 11 R12 R 13 R 14 R 15 R 16 R 17 R 18 Each is independently selected from alkyl groups;

[0139] R 21 ', R 22 ', R 23 ', R 24 ', R 25 ', R 26 ', R 27 ', R 28 Each is independently selected from alkenyl groups.

[0140] Specifically, R 21 ', R 22 ', R 23 ', R 24 ', R 25 ', R 26 ', R 27 ', R 28 Each compound is independently selected from alkenyl groups, containing carbon-carbon double bonds, and structural formula 5 contains an amino group. The amino group in compound 3 reacts with the carbon-carbon double bond in compound 4 to generate the compound shown in structural formula 2. Similarly, the second mixture is extracted to remove unreacted reactant compound 3, while also removing the second solvent. The extraction is performed at least once, preferably more than once. After extraction, the mixture is distilled under reduced pressure to remove excess compound 4 and water, yielding the second chain extender.

[0141] In some embodiments, the reaction temperature in the second heating reaction is 60~80℃, and the reaction time is 12~24h.

[0142] Specifically, the reaction temperature in the second heating reaction can be 60℃, 62℃, 65℃, 67℃, 68℃, 70℃, 73℃, 75℃, 77℃, 79℃, 80℃, etc., as long as the reaction temperature of the second heating reaction is within the range of 60℃ to 80℃. If the reaction temperature of the second heating reaction is below 60℃, compounds 3 and 4 cannot react effectively; if the reaction temperature of the second heating reaction is above 80℃, the reaction temperature is too high, and the reaction byproducts increase.

[0143] In some embodiments, the molar ratio of compound 3 to compound 4 is 1:(8.2~8.5).

[0144] Specifically, when the molar ratio of compound 3 to compound 4 is within the range of 1:(8.2~8.5), the compound shown in structural formula 2 can be generated at a lower cost.

[0145] In some embodiments, the second solvent includes one or more of alcohol solvents, ethyl acetate, N-methylpyrrolidone, and dipropylene glycol dimethyl ether.

[0146] Specifically, alcohol solvents include methanol, ethanol, isopropanol, etc.

[0147] In some preferred embodiments, compound 3 is diisopropanolamine. R in compound 4 11 R 12 R 13 R 14 R 15 R 16 R 17 R 18 Each is independently selected from ethyl, R 21 R 22 R 23 R 24 R 25 R 26 R 27 R 28 Each is independently selected from vinyl.

[0148] It should be noted that compounds 3 and 4 were mixed thoroughly under a protective atmosphere; and the reaction was carried out under a protective atmosphere at a temperature of 60-80°C.

[0149] Thirdly, this application provides an application of the polyurethane composition described above or the polyurethane composition prepared by the method described above in thermal insulation materials.

[0150] The polyurethane composition provided in this application can be used in thermal insulation materials, such as for thermal insulation in the building sector, industrial thermal insulation sector, and cold chain logistics sector.

[0151] More preferably, the polyurethane composition is used as an insulation material in the building sector, such as by injecting the polyurethane composition into the interlayer between the working pipe and the outer protective pipe for use as an insulation material.

[0152] The present invention will be further illustrated by the following examples.

[0153] Example 1

[0154] S1 Preparation of the first chain extender:

[0155] Raw materials: Compound 1 is diisopropanolamine, Compound 2 is perfluorooctyl ethyl acrylate; the first solvent is methanol;

[0156] Preparation: 100g of perfluorooctyl ethyl acrylate, 30g of diisopropanolamine, and 800mL of methanol were added to a clean three-necked flask and stirred evenly under a nitrogen atmosphere. The mixture was then transferred to an oil bath at 60℃ and reacted for 12 hours. After cooling to room temperature, the mixture was extracted multiple times with distilled water to remove methanol and unreacted diisopropanolamine. Excess perfluorooctyl ethyl acrylate and deionized water were then removed by vacuum distillation to obtain the first chain extender product.

[0157] S2: Preparation of the second chain extender:

[0158] Raw materials: Compound 3 is diisopropanolamine, and R in compound 4 11 R 12 R 13 R 14 R 15 R 16 R 17 R 18 Each is independently selected from ethyl, R 21 R 22 R 23 R 24 R 25 R 26 R 27 R 28 Each component is independently selected from vinyl groups. The second solvent is isopropanol.

[0159] Preparation: 100g of the above compound 4, 83.6g of diisopropanolamine, and 700mL of isopropanol were added to a clean three-necked flask and stirred evenly under a nitrogen atmosphere. The mixture was then transferred to an oil bath at 80℃ and reacted for 24 hours. After cooling to room temperature, the mixture was extracted multiple times with distilled water to remove the solvent isopropanol and unreacted diisopropanolamine. The excess compound 4 and deionized water were then removed by vacuum distillation to obtain the second chain extender product.

[0160] S3: Preparation of polyurethane

[0161] S31: Raw materials: Polyether polyol I is Lanxing Dongda DV-125, with a hydroxyl value of 440~460 KOH / g. Polyether polyol II is Jining Liduo 403, with a hydroxyl value of 745~775 KOH / g. Polyester polyol is Jining Liduo NLD-240B, with a hydroxyl value of 230~250 KOH / g. The organic salt catalyst is dibutyltin dilaurate, a product of Jinan Dahui Chemical T-2; the tertiary amine catalyst is triethylenediamine, a product of Henan Bangrun Chemical TEDA; the first chain extender prepared in step S1 and the second chain extender prepared in step S2; the foaming agent is water and dichlorofluoroethane, which was purchased from Jinan Decheng Chemical; the foam leveling agent was purchased from Jiangsu Meiside Company.

[0162] The isocyanate is polymethylene polyphenyl polyisocyanate, a product of Wanhua PM-200.

[0163] S32: Preparation

[0164] Component A: 45 parts polyether polyol I, 35 parts polyether polyol II, 20 parts polyester polyol, 8 parts chain extender, 2.5 parts dibutyltin dilaurate, 1 part triethylenediamine, 0.8 parts water, 25 parts dichlorofluoroethane, and 3 parts foam stabilizer; the mass ratio of the first chain extender to the second chain extender is 1:0.2.

[0165] Component B: 150 parts of polymethylene polyphenyl polyisocyanate.

[0166] The polyurethane composition is obtained by uniformly mixing component A and component B. The polyurethane composition is then injected into the interlayer between the working pipe and the outer protective pipe for use as an insulation material.

[0167] Examples 2-14 and Comparative Examples 1-7

[0168] Examples 2-14 and Comparative Examples 1-7 are largely the same as those in Example 1, except that the number of components in polyether polyol I, polyether polyol II, polyester polyol, chain extender, dibutyltin dilaurate, triethylenediamine, water, dichlorofluoroethane, foam stabilizer, and polymethylene polyphenyl polyisocyanate are different; and the mass ratio of the first chain extender to the second chain extender is different. See Table 1 for details.

[0169] Table 1

[0170]

[0171] Comparative Example 8

[0172] This comparative example is similar to Example 1 in most steps, except that the second chain extender does not conform to the compound shown in structural formula 2; the second chain extender is... The rest is the same as in Example 1.

[0173] Performance testing

[0174] Test samples were prepared from the polyurethane compositions obtained in the above embodiments and comparative examples, and the following tests were conducted.

[0175] 1. Compressive strength

[0176] The specimen size is 50 mm × 50 mm × 50 mm. Measure the specimen dimensions to an accuracy of 0.05 mm, at least three points, and take the average value. Place the specimen between the pressure plates and apply a compressive load at the rate specified in GB / T8813-2018. The relative deformation must reach at least 10%. After the specimen fails, record the load count.

[0177] 2. Density

[0178] Cut a regularly shaped cuboid from the polyurethane composition, calculate its volume, and then weigh it on a balance to avoid the pressure around the sample affecting the measurement results; density = mass / volume.

[0179] 3. Water absorption rate

[0180] After preparing polyurethane foam from the polyurethane composition, immerse it in boiling water at normal pressure for 90 minutes, calculate the mass difference before and after, and the water absorption rate = mass difference / original mass.

[0181] 4. Thermal conductivity

[0182] The heat flow meter method is a comparative method based on the principle of one-dimensional steady-state heat conduction. A sample is inserted between two plates, and a constant unidirectional heat flow is introduced perpendicularly. A calibrated heat flow sensor, positioned between the plates and the sample, measures the heat flow through the sample. The heat flow method is suitable for materials with low thermal conductivity. During testing, the sample is sandwiched between two heat flow sensors. After the temperature gradient stabilizes, the sample thickness, the temperature gradient between the plates, and the heat flow through the sample are measured to calculate the absolute value of the thermal conductivity. It is suitable for testing materials with thermal conductivity ranging from 0.001 to 50 W / m•K. The thermal conductivity of the sample is tested at 50°C.

[0183] 5. Heat resistance test

[0184] The sample size of the above polyurethane composition was 100*100*50mm. After preparing polyurethane foam, it was placed in a 200℃ oven and stored for 120 hours before the heat resistance was tested.

[0185] The test results are shown in Table 2. It should be noted that the requirements in Table 2 are based on the requirements for thermal insulation materials in the building industry.

[0186] Table 2

[0187]

[0188] As shown in Tables 1 and 2, compared with Comparative Examples 1-3, Comparative Example 1, lacking both the first and second chain extenders, exhibits low compressive strength, high water absorption, and poor heat resistance. Comparative Example 2, containing only polyether polyol and a large amount of it (greater than 70-90 parts), results in increased thermal conductivity, poor heat resistance, and low compressive strength in the polyurethane composition. Comparative Example 3, with a polyester polyol content greater than 10-30 parts and polyether polyol content in the 70-90 part range, yields a polyurethane composition with high compressive strength but poor water absorption, high thermal conductivity, and poor thermal insulation performance. The comparison between Examples 1 and Comparative Examples 1-3 demonstrates that adding 70-90 parts of polyether polyol, 10-30 parts of polyester polyol, and 145-147 parts of isocyanate to the polyurethane composition, under the action of a catalyst, first chain extender, second chain extender, foam leveler, and foaming agent, results in a polyurethane composition with high compressive strength and a density ≥60 kg / m³. 3 It has low water absorption, low thermal conductivity, good thermal insulation performance, and good heat resistance.

[0189] Comparing Examples 1-3 and Comparative Examples 4-7, Comparative Examples 6 and 7, with the addition of either the first chain extender or the second chain extender alone, showed slightly lower compressive strength and higher water absorption. Comparative Example 4, with a total chain extender content of less than 5-10 parts, presumably contained less chain extender, resulting in poor system compatibility and high water absorption, poor heat resistance, and low compressive strength in the resulting polyurethane composition. Comparative Example 5, with a total chain extender content of more than 5-10 parts, presumably contained too much chain extender, altering the molecular chain stacking pattern, reducing free volume, and weakening the heat insulation effect, resulting in a polyurethane composition with high thermal conductivity and poor heat insulation performance. The comparison between Examples 1 and Comparative Examples 4-7 shows that when the total chain extender content in the polyurethane composition is 5-10 parts, and the chain extender includes the first chain extender shown in structural formula 1 and the second chain extender shown in structural formula 2, the resulting polyurethane composition exhibits high compressive strength, high water absorption, good heat resistance, low thermal conductivity, and good heat insulation performance.

[0190] Comparing Examples 1 and 4-8 with Examples 11 and 12, the proportions of polyester polyol and isocyanate were adjusted according to the polyether polyol. It is shown that the proportions of polyether polyol I are 40-50 parts and the proportions of polyether polyol II are 30-40 parts. The mass ratio of polyether polyol I, polyether polyol II and polyester polyol is in the range of (1.2-5):(1-4):1. The resulting polyurethane composition has the effects of high compressive strength, high water absorption, good heat resistance, low thermal conductivity and good heat insulation effect.

[0191] Comparing Examples 1, 9, 10 and Examples 13, 14, when the mass ratio of the first chain extender to the second chain extender is less than 1:0.1, the second chain extender content is low, the incompatibility problem still exists, and the polyurethane has low compressive strength and high water absorption. When the mass ratio of the first chain extender to the second chain extender is greater than 1:0.3, the second chain extender content is high, the rigidity is strong, and the mechanical properties of the resulting polyurethane composition are poor. This indicates that when the mass ratio of the first chain extender to the second chain extender is in the range of 1:(0.1~0.3), the resulting polyurethane composition has better mechanical properties.

[0192] Comparing Example 1 and Comparative Example 8, the second chain extender added in Comparative Example 8 does not satisfy the compound shown in Structural Formula 2. Although it also contains a cage-like structure composed of silicon-oxygen bonds, it does not conform to the compound shown in Structural Formula 2. The two chain extenders in Comparative Example 8 cannot achieve a good synergistic effect. The chain extender has poor compatibility with each component, high compressive strength, and high water absorption. This indicates that the added second chain extender satisfies the compound shown in Structural Formula 2, and the first chain extender satisfies the compound shown in Structural Formula 1. The first and second chain extenders work synergistically to improve the strength of polyurethane foam cells, optimize the best hydrophobic properties, and the resulting polyurethane composition has strong compressive strength, good hydrophobicity, and can effectively maintain continuous thermal insulation function. The polyurethane composition has low thermal conductivity and good heat resistance.

[0193] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A polyurethane composition, characterized in that, The polyurethane composition comprises the following raw materials: A component: 70-90 parts of polyether polyol, 10-30 parts of polyester polyol, 5-10 parts of chain extender, 2.5-4.5 parts of catalyst, 2-5 parts of cell regulator, 15.5-36 parts of foaming agent; B component: 145-147 parts of isocyanate; The chain extender comprises a first chain extender and a second chain extender, the first chain extender is a compound shown in structural formula 1: Wherein, R1, R2 are each independently selected from alkylene; R3, R4 are each independently selected from hydroxyl-terminated alkyl chain; R5 is selected from at least one hydrogen atom substituted with fluorine alkyl; The second chain extender is a compound shown in structural formula 2: wherein R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 , R 18 , R 21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 , R 28 are each independently selected from alkylene; R6, R7 are selected from at least one of hydroxyl-terminated alkyl chain, alkyl, and at least one of R6 and R7 is selected from hydroxyl-terminated alkyl chain; The polyether polyol comprises polyether polyol I with a hydroxyl value of 440-460 mgKOH / g and polyether polyol II with a hydroxyl value of 745-775 mgKOH / g; In the polyurethane composition, the fraction of the polyether polyol I is 40-50 parts, and the fraction of the polyether polyol II is 30-40 parts; the mass ratio of the polyether polyol I, the polyether polyol II and the polyester polyol is (1.2-5):(1-4):1; The polyester polyol has a hydroxyl value of 230-250 mgKOH / g.

2. The polyurethane composition according to claim 1, characterized in that, R1, R2 are each independently selected from C1-C5 alkylene; R3, R4 are each independently selected from C1-C5 alkyl chain terminated by hydroxyl; R5 is selected from C3-C15 alkyl with at least one hydrogen atom substituted by fluorine; R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 , R 18 , R 21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 , R 28 is selected from C1-C5 alkylene; R6, R7 are selected from at least one of C1-C5 alkyl chain terminated by hydroxyl, C1-C5 alkyl, and at least one of R6 and R7 is selected from C1-C5 alkyl chain terminated by hydroxyl.

3. The polyurethane composition according to claim 1 or 2, characterized in that, The mass ratio of the first chain extender to the second chain extender is 1:(0.1-0.3).

4. The polyurethane composition according to claim 3, characterized in that, R5 is selected from C6-C12 perfluoroalkyl.

5. The polyurethane composition according to claim 1, characterized in that, The catalyst comprises at least one of organic salt catalyst and tertiary amine catalyst; The organic salt catalyst comprises one or more of dibutyltin dilaurate, potassium acetate, potassium iso-octoate, potassium oleate, stannous octoate; The tertiary amine catalyst comprises one or more of triethylenediamine, triethylene diamine, dimethylcyclohexylamine, triethanolamine, triethylamine, trimethyl tertiary amine, dimethyl ethanolamine; The cell regulator comprises silicone oil; The foaming agent comprises one or both of water and monofluorodichloroethane; The isocyanate comprises one or more of diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate, dicyclohexylmethane diisocyanate, xylylene diisocyanate, naphthalene-1,5-diisocyanate, p-phenylene diisocyanate, tetramethylxylylene diisocyanate.

6. A process for the production of the polyurethane composition according to any one of claims 1 to 5, characterized in that, The method comprises the following steps: Preparation of the A component and the B component according to parts by weight; Mixing the A component and the B component uniformly to obtain the polyurethane composition.

7. The method of producing a polyurethane composition according to claim 6, characterized in that, The preparation method of the first chain extender comprises the following steps: The compound 1, the compound 2 and a first solvent are uniformly mixed under a protective atmosphere, and a first heating reaction is carried out to obtain a first mixture, and the first mixture is extracted and distilled under reduced pressure to obtain the first chain extender; The reaction temperature in the first heating reaction is 60-80 DEG C, and the reaction time is 12-24 h; The compound 1 is a compound shown in structural formula 3, and the compound 2 is a compound shown in structural formula 4, 、 Wherein, R3, R4 are each independently selected from a hydroxyl-terminated alkyl chain; R2' is selected from an alkenyl group; R1 is selected from an alkylene group, and R5 is selected from an alkyl group in which at least one hydrogen atom is replaced by fluorine; The molar ratio of the compound 1 to the compound 2 is 1: (1.1-1.3) ; The first solvent includes one or more of an alcohol solvent, ethyl acetate, N-methyl pyrrolidone and dipropylene glycol dimethyl ether.

8. The method of making a polyurethane composition according to claim 6, characterized in that, The preparation method of the second chain extender includes the following steps: The compound 3, the compound 4 and a second solvent are uniformly mixed under a protective atmosphere, and a second heating reaction is carried out to obtain a second mixture, and the second mixture is extracted and distilled under reduced pressure to obtain the second chain extender; The reaction temperature in the second heating reaction is 60-80 DEG C, and the reaction time is 12-24 h; The compound 3 is a compound shown in structural formula 5, and the compound 4 is a compound shown in structural formula 6, 、 Wherein, R6, R7 are each independently selected from an alkyl group and a hydroxyl-terminated alkyl chain; and at least one of R6 and R7 is selected from a hydroxyl-terminated alkyl chain; R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 , R 18 each independently is selected from alkylene; R 21 R 22 R 23 R 24 R 25 R 26 R 27 R 28 R each independently selected from alkenyl; The molar ratio of the compound 3 to the compound 4 is 1: (8.2-8.5) ; The second solvent includes one or more of an alcohol solvent, ethyl acetate, N-methyl pyrrolidone and dipropylene glycol dimethyl ether.

9. The application of the polyurethane composition prepared by the preparation method of the polyurethane composition of any one of claims 1-5 or any one of claims 6-8 in thermal insulation materials.

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