A modified polyurethane with a long-chain branched structure and a modified polyurethane foam material prepared therefrom.

Abstract

This invention relates to the field of polyurethane technology, specifically to a modified polyurethane with a long-chain branched structure and a modified polyurethane foam material prepared therefrom. The invention first reacts a first polyurethane (such as thermoplastic polyurethane) with an excess of diisocyanate, introducing multiple isocyanate groups onto the side chains of the first polyurethane molecular chain to prepare a polyurethane polyisocyanate, i.e., a first polyurethane-grafted isocyanate copolymer. Using this polyurethane polyisocyanate as a modifier, it is then reacted with a second polyurethane (such as thermoplastic polyurethane) to obtain a modified polyurethane with a long-chain branched structure. Because the prepared polyurethane polyisocyanate has better compatibility with the second polyurethane, it is beneficial to improve the foaming performance of the modified polyurethane with the long-chain branched structure, resulting in a modified polyurethane foam material with higher expansion ratio, more uniform cell structure, and lower thermal conductivity.

Description

Technical Field

[0001] This invention relates to the field of polyurethane technology, specifically to a modified polyurethane with a long-chain branched structure and a modified polyurethane foam material prepared therefrom. Background Technology

[0002] Thermoplastic polyurethane elastomer (TPU) is a type of elastomer that can be plasticized by heat and dissolved by solvents. It possesses excellent comprehensive properties such as high strength, high toughness, wear resistance, and oil resistance. Due to its good processability, it is currently widely used in defense, medical, and food industries. TPU is an (AB) n TPU is a block linear polymer, specifically composed of flexible soft segments and rigid hard segments. Different segment structures in TPU exhibit different properties, and the type of segment structure is primarily determined by the raw material. Introducing side groups into the molecular structure reduces the orientation and crystallinity between macromolecules, leading to decreased mechanical properties and poorer swelling performance; conversely, certain chemical crosslinking can improve the elastomer's tensile stress and solvent resistance, and reduce permanent deformation. In TPU, A is a high molecular weight polyester or polyether of 1,000–6,000 g / mol, and B is a diol containing 2–12 straight-chain carbon atoms. The chemical structure between the A and B segments is a diisocyanate. Thermoplastic polyurethane relies on intermolecular hydrogen bonding or mild crosslinking between macromolecular chains. These two crosslinking structures are reversible with increasing or decreasing temperature. In the molten or solution state, intermolecular forces weaken, but after cooling or solvent evaporation, strong intermolecular forces reconnect them, restoring the original solid properties. Due to its excellent elasticity, flexibility, and skin-friendliness, TPU is widely used in the clothing industry.

[0003] Flexible foam materials are made from raw materials such as plastics (PE, EVA, etc.) and rubber (SBR, CR, etc.), along with additives such as catalysts, foam stabilizers, and foaming agents. Through physical foaming or cross-linking foaming, a large number of fine foam particles are created within the plastics and rubber, increasing their volume and decreasing their density. Flexible foam materials are lightweight, flexible, and possess functions such as cushioning, sound absorption, shock absorption, heat insulation, and filtration. They are widely used in industries such as electronics, home appliances, automobiles, and sports and leisure.

[0004] After foaming, TPU has advantages such as sound absorption, heat insulation, and increased softness, making it particularly suitable for the apparel industry, such as shoe sole materials and thermal clothing materials. However, there are some problems during the TPU foaming process. For example, the melt strength of ordinary TPU is limited, which restricts the foaming ratio, causing TPU foam materials to be prone to pore breakage at high foaming ratios. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a modified polyurethane with a long-chain branched structure and a modified polyurethane foam material prepared therefrom. The modified polyurethane features a long-chain branched structure, and the modified polyurethane foam material prepared therefrom has the characteristics of high foaming ratio, uniform cell size, good warmth retention, and good flexibility, making it particularly suitable for the field of clothing insulation.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: A method for preparing a modified polyurethane with a long-chain branched structure, the method comprising the following steps: (1) The first polyurethane and diisocyanate are mixed and reacted to prepare the first polyurethane-grafted isocyanate copolymer; (2) The first polyurethane grafted isocyanate copolymer and the second polyurethane from step (1) are mixed and reacted to prepare the modified polyurethane with the long-chain branched structure.

[0007] According to an embodiment of the present invention, in step (1), the first polyurethane is selected from thermoplastic polyurethane, which is either polyester-type or polyether-type thermoplastic polyurethane. The specific structure of the polyester-type or polyether-type thermoplastic polyurethane is not particularly limited. The source of the thermoplastic polyurethane is not particularly limited; it can be obtained through commercial purchase or prepared using methods known in the art.

[0008] According to an embodiment of the present invention, in step (1), the molecular weight of the first polyurethane is greater than or equal to 5,000 g / mol; preferably, the molecular weight of the first polyurethane is 5,000-50,000 g / mol, for example, 5,000 g / mol, 10,000 g / mol, 20,000 g / mol, 30,000 g / mol, 40,000 g / mol or 50,000 g / mol. Surprisingly, it has been found that when the molecular weight of the first polyurethane is greater than or equal to 5,000 g / mol, it can be guaranteed that a modified polyurethane with a long-chain branched structure is finally obtained, and at the same time, it can be guaranteed that the foamed material prepared from the obtained modified polyurethane has the characteristics of high foaming ratio, uniform cell size, good heat retention and flexibility.

[0009] According to an embodiment of the present invention, in step (1), the diisocyanate includes, but is not limited to, at least one of toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate (HMDI), diphenylmethane diisocyanate (MDI), and lysine diisocyanate (LDI).

[0010] According to an embodiment of the present invention, in step (1), the molar amount of diisocyanate is 2-10 times the molar amount of NH bonds in the first polyurethane, for example, 2, 3, 4, 5, 6, 7, 8, 9, or 10 times. In this case, the molar amount of diisocyanate is excessive relative to the molar amount of NH bonds in the first polyurethane. By adding excess diisocyanate, it can be ensured that all NH bonds in the first polyurethane react completely (generating -NH-CO-NH- bonds), obtaining a first polyurethane grafted isocyanate copolymer. This is beneficial for obtaining a modified polyurethane with a long-chain branched structure.

[0011] According to an embodiment of the present invention, in step (1), the reaction of the first polyurethane and the diisocyanate is carried out under the condition of an added organic solvent; wherein the added organic solvent is an organic solvent that is free of active hydrogen and water and can dissolve the first polyurethane and the diisocyanate, such as at least one of methyl ethyl ketone (MEK), cyclohexanone (CHN), tetrahydrofuran (THF), dioxane and dimethylformamide (DMF).

[0012] According to an embodiment of the present invention, in step (1), the reaction temperature is 20-100°C, for example, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, or 100°C. The reaction time is 1-10 hours, for example, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, or 10 hours.

[0013] According to an embodiment of the present invention, in step (1), after the reaction is completed, unreacted diisocyanate is washed away to obtain a first polyurethane-grafted isocyanate copolymer. Preferably, after the reaction is completed, an organic solvent that does not dissolve the first polyurethane but can dissolve the diisocyanate, such as at least one of ethyl acetate, methyl tert-butyl ether, etc., which does not contain active hydrogen and water, is added to the reactants to precipitate the polymer, and the polymer is washed with the organic solvent to remove unreacted diisocyanate, thereby obtaining the first polyurethane-grafted isocyanate copolymer.

[0014] According to an embodiment of the present invention, in step (2), the second polyurethane is selected from thermoplastic polyurethane, which is either polyester-type or polyether-type thermoplastic polyurethane. The specific structure of the polyester-type or polyether-type thermoplastic polyurethane is not particularly limited. The source of the thermoplastic polyurethane is not particularly limited; it can be obtained through commercial purchase or prepared using methods known in the art.

[0015] According to an embodiment of the present invention, in step (2), the first polyurethane and the second polyurethane may be the same or different.

[0016] According to an embodiment of the present invention, in step (2), the melt index of the second polyurethane is 5-150 g / 10 min, for example, 5 g / 10 min, 10 g / 10 min, 20 g / 10 min, 50 g / 10 min, 60 g / 10 min, 80 g / 10 min, 100 g / 10 min, 120 g / 10 min or 150 g / 10 min.

[0017] According to an embodiment of the present invention, in step (2), the mass of the first polyurethane grafted isocyanate copolymer accounts for 0.5-20 wt% of the total mass of the first polyurethane grafted isocyanate copolymer and the second polyurethane, preferably 0.6-10 wt%, and even more preferably 0.8-6 wt%, for example 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, 5.5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 15 wt%, 16 wt%, 18 wt%, or 20 wt%. Surprisingly, when the mass of the first polyurethane grafted isocyanate copolymer accounts for 0.5-20 wt% of the total mass of the first polyurethane grafted isocyanate copolymer and the second polyurethane, the modified polyurethane with a long-chain branched structure obtained has excellent foaming properties, and modified polyurethane foam materials with higher foaming ratio, more uniform cell structure, and lower thermal conductivity can be prepared.

[0018] According to an embodiment of the present invention, in step (2), the reaction of the first thermoplastic polyurethane grafted isocyanate copolymer and the second thermoplastic polyurethane is carried out in a heated molten state without the addition of solvent, such as in a mixer or screw extruder.

[0019] According to an embodiment of the present invention, in step (2), the reaction temperature is 100-200°C, for example, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, or 200°C. The reaction time is 5 minutes to 10 hours, for example, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, or 10 hours.

[0020] The present invention also provides a modified polyurethane with a long-chain branched structure prepared by the above method.

[0021] According to an embodiment of the present invention, the softening point of the modified polyurethane with a long-chain branched structure is 60-130°C, for example, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C or 130°C; the Shore hardness is 60-95A, for example, 60A, 65A, 70A, 75A, 80A, 85A, 90A or 95A; and the melt flow index is 2-150 g / 10 min, for example, 2 g / 10 min, 3 g / 10 min, 5 g / 10 min, 10 g / 10 min, 15 g / 10 min, 20 g / 10 min, 50 g / 10 min, 60 g / 10 min, 80 g / 10 min, 100 g / 10 min, 120 g / 10 min or 150 g / 10 min.

[0022] The present invention also provides a method for preparing a modified polyurethane foam material, the method comprising the following steps: After drying the modified polyurethane with the long-chain branched structure, it was added to an autoclave and carbon dioxide was injected. The autoclave was heated to the foaming temperature and held for a certain period of time. Then, the pressure was released to atmospheric pressure and cooled to room temperature to obtain the modified polyurethane foam material.

[0023] According to an embodiment of the present invention, the drying time does not exceed 48 hours, preferably 6-48 hours. The purpose of the drying is to dehydrate the modified polyurethane with a long-chain branched structure, which is beneficial to obtaining a modified polyurethane foam material with high foaming rate, better heat retention and better flexibility.

[0024] According to an embodiment of the present invention, the drying can be carried out under normal pressure or under vacuum conditions.

[0025] According to an embodiment of the present invention, the drying temperature is preferably such that the materials do not stick together; for example, the drying temperature is 50-90°C.

[0026] According to an embodiment of the present invention, the foaming temperature is 130-250°C, for example, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C or 250°C.

[0027] According to an embodiment of the present invention, the pressure of the carbon dioxide is 2-20 MPa, for example, 2 MPa, 3 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, 10 MPa, 11 MPa, 12 MPa, 15 MPa, 16 MPa, 18 MPa or 20 MPa.

[0028] According to an embodiment of the present invention, the stay time is 1-8 hours, for example, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours or 8 hours.

[0029] According to an embodiment of the present invention, the pressure relief rate is 2-20 MPa / 60s, for example, 2 MPa / 60s, 3 MPa / 60s, 4 MPa / 60s, 5 MPa / 60s, 6 MPa / 60s, 7 MPa / 60s, 8 MPa / 60s, 9 MPa / 60s, 10 MPa / 60s, 11 MPa / 60s, 12 MPa / 60s, 15 MPa / 60s, 16 MPa / 60s, 18 MPa / 60s, or 20 MPa / 60s.

[0030] According to an embodiment of the present invention, the modified polyurethane foam material is cooled to room temperature by introducing cooling water into the autoclave.

[0031] The present invention also provides a modified polyurethane foam material prepared by the above method.

[0032] According to an embodiment of the present invention, the expansion ratio of the modified polyurethane foam material is in the range of 25-30 times, where the expansion ratio refers to the ratio of the volume of the modified polyurethane foam material after foaming to the volume of the modified polyurethane foam material before foaming.

[0033] According to an embodiment of the present invention, the thermal conductivity of the modified polyurethane foam material is 0.020-0.030 W / (m·K).

[0034] The present invention also provides the use of the above-mentioned modified polyurethane foam material in the field of clothing thermal insulation.

[0035] According to an embodiment of the present invention, the modified polyurethane foam material is cut to prepare a foam sheet with a thickness of 0.5-3 mm for use in the field of clothing insulation.

[0036] The beneficial effects of this invention are: This invention first reacts a first polyurethane (such as thermoplastic polyurethane) with an excess of diisocyanate, introducing multiple isocyanate groups onto the side chains of the first polyurethane molecular chain to prepare a polyurethane polyisocyanate, namely a first polyurethane-grafted isocyanate copolymer. Using this polyurethane polyisocyanate as a modifier, it is then reacted with a second polyurethane (such as thermoplastic polyurethane) to obtain a modified polyurethane with a long-chain branched structure. Because the prepared polyurethane polyisocyanate has better compatibility with the second polyurethane, it is beneficial to improve the foaming performance of the modified polyurethane with a long-chain branched structure, resulting in a modified polyurethane foam material with higher foaming ratio, more uniform cell structure, and lower thermal conductivity. Detailed Implementation

[0037] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0038] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0039] Thermal conductivity test: according to the protective hot plate method of GB / T 10294-2008.

[0040] Melt flow index test: Tested according to GB / T 3682.1-2023, the test temperature is 210℃, and the total test load is 2.16kg.

[0041] Example 1 10g of commercially available BASF thermoplastic polyurethane TPU S85A (polyester type, hardness 84A, molecular weight 26,000g / mol, melt index 35g / 10min) was dissolved in 100mL of tetrahydrofuran. 10g of MDI was dissolved in 100mL of tetrahydrofuran. The TPU S85A solution was added dropwise to the stirred MDI solution at room temperature. After the addition was complete, the reaction was carried out at 50℃ for 3h. After the reaction was complete, 1000mL of methyl tert-butyl ether was added to precipitate the polymer. After the liquid was extracted, 500mL of methyl tert-butyl ether was added twice to wash the polymer. The polymer was then vacuum dried at 60℃ for 24h to obtain the TPU-grafted MDI copolymer.

[0042] Take 2g of the TPU-grafted MDI copolymer prepared above and 50g of commercially available BASF thermoplastic polyurethane TPUS85A, and mix them in a mixer at 180°C for 15min. Remove the polymer. Repeat the above operation several times to prepare a sufficient amount of TPU with a long-chain branched structure. The melt index was tested to be 10.5g / 10min.

[0043] 100g of the TPU with long-chain branched structure prepared above was added to a 10L autoclave, heated to 150℃, and filled with carbon dioxide. The pressure was maintained at 15MPa for 3 hours, and then the autoclave pressure was reduced to atmospheric pressure within 60s. After reducing to atmospheric pressure, cooling water was immediately introduced to cool the sample, resulting in foamed TPU. The foaming ratio of this foamed TPU was 25.

[0044] The obtained foamed TPU sample was rotary cut to obtain a sheet with a thickness of 1 mm. The thermal conductivity of the sheet was tested to be 0.028 W / (m·K).

[0045] Example 2 10g of commercially available BASF thermoplastic polyurethane TPU 1185A (polyether type, hardness 87A, molecular weight 38,000g / mol, melt index 15g / 10min) was dissolved in 100mL of tetrahydrofuran. 10g of HDI was dissolved in 100mL of tetrahydrofuran. The TPU 1185A solution was added dropwise to the stirred HDI solution at room temperature. After the addition was complete, the reaction was carried out at 50℃ for 3h. After the reaction was complete, 1000mL of methyl tert-butyl ether was added to precipitate the polymer. After the liquid was extracted, 500mL of methyl tert-butyl ether was added twice to wash the product. The product was then vacuum dried at 60℃ for 24h to obtain the TPU-grafted HDI copolymer.

[0046] Take 3g of the TPU-grafted HDI copolymer prepared above and 50g of commercially available BASF thermoplastic polyurethane TPU1185A, and mix them in a mixer at 180°C for 15min. Remove the polymer. Repeat the above operation several times to prepare a sufficient amount of TPU with a long-chain branched structure. The melt index was tested to be 4.8g / 10min.

[0047] 100g of the TPU with long-chain branched structure prepared above was added to a 10L autoclave, heated to 160℃, and filled with carbon dioxide. The pressure was maintained at 15MPa for 3 hours, and then the autoclave pressure was reduced to atmospheric pressure within 60s. After reducing to atmospheric pressure, cooling water was immediately introduced to cool the sample, resulting in foamed TPU. The foaming ratio of this foamed TPU was 26.

[0048] The obtained foamed TPU sample was rotary cut to obtain a sheet with a thickness of 1 mm. The thermal conductivity of the sheet was tested to be 0.028 W / (m·K).

[0049] Example 3 Take 3g of the TPU-grafted HDI copolymer prepared in Example 2 and 50g of commercially available BASF thermoplastic polyurethane TPU 1154 D (polyether type, hardness 53D, molecular weight 42,000 g / mol, melt index 10.4 g / 10 min), and mix them in an internal mixer at 180°C for 15 min. Remove the polymer. Repeat the above operation multiple times to prepare a sufficient amount of TPU with a long-chain branched structure. Its melt index was tested to be 3.1 g / 10 min.

[0050] 100g of the TPU with long-chain branched structure prepared above was added to a 10L autoclave, heated to 130℃, and filled with carbon dioxide. The pressure was maintained at 15MPa for 3 hours, and then the autoclave pressure was reduced to atmospheric pressure within 60s. After reducing to atmospheric pressure, cooling water was immediately introduced to cool the sample, resulting in foamed TPU. The foaming ratio of this foamed TPU was 28.

[0051] The obtained foamed TPU sample was rotary cut to obtain a sheet with a thickness of 1 mm. The thermal conductivity of the sheet was tested to be 0.026 W / (m·K).

[0052] Comparative Example 1 100g of commercially available BASF thermoplastic polyurethane (TPU) 1185A was added to a 10L autoclave, heated to 160°C, and filled with carbon dioxide. The pressure was maintained at 15MPa for 3 hours, and then the autoclave pressure was reduced to atmospheric pressure within 60 seconds. After reducing to atmospheric pressure, cooling water was immediately introduced to cool the sample, resulting in foamed TPU. The foaming ratio of this foamed TPU was 16.

[0053] The obtained foamed TPU sample was rotary cut to obtain a sheet with a thickness of 1 mm. The thermal conductivity of the sheet was tested to be 0.045 W / (m·K).

[0054] Comparative Example 2 100g of the TPU-grafted HDI copolymer prepared in Example 2 was added to a 10L autoclave, heated to 160°C, and carbon dioxide was introduced. The pressure was maintained at 15MPa for 3 hours, and then the autoclave pressure was reduced to atmospheric pressure within 60s. After reducing to atmospheric pressure, cooling water was immediately introduced to cool the sample, resulting in foamed TPU. The foaming ratio of this foamed TPU was 18.

[0055] The obtained foamed TPU sample was rotary cut to obtain a sheet with a thickness of 1 mm. The thermal conductivity of the sheet was tested to be 0.042 W / (m·K).

[0056] Comparative Example 3 Take 6g of HDI and 100g of commercially available BASF thermoplastic polyurethane TPU 1185A, and mix them in an internal mixer at 180°C for 15 minutes. Remove the polymer.

[0057] 100g of the polymer prepared above was added to a 10L autoclave, heated to 160℃, and carbon dioxide was introduced. The pressure was maintained at 15MPa for 3 hours, and then the autoclave pressure was reduced to atmospheric pressure within 60s. After reducing to atmospheric pressure, cooling water was immediately introduced to cool the sample, resulting in foamed TPU. The foaming ratio of this foamed TPU was 16.

[0058] The obtained foamed TPU sample was rotary cut to obtain a sheet with a thickness of 1 mm. The thermal conductivity of the sheet was tested to be 0.043 W / (m·K).

[0059] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a modified polyurethane having a long chain branched structure, wherein, The preparation method includes the following steps: (1) The first polyurethane and diisocyanate are mixed and reacted to prepare the first polyurethane-grafted isocyanate copolymer; (2) The first polyurethane grafted isocyanate copolymer and the second polyurethane from step (1) are mixed and reacted to prepare the modified polyurethane with the long-chain branched structure.

2. The production method according to claim 1, wherein In step (1), the first polyurethane is selected from thermoplastic polyurethane, and the thermoplastic polyurethane is polyester type or polyether type thermoplastic polyurethane. And / or, in step (1), the molecular weight of the first polyurethane is greater than or equal to 5,000 g / mol; And / or, in step (1), the diisocyanate includes at least one of toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate (HMDI), diphenylmethane diisocyanate (MDI), and lysine diisocyanate (LDI); And / or, in step (1), the molar amount of the diisocyanate is 2-10 times the molar amount of NH bonds in the first polyurethane; And / or, in step (1), the temperature of the reaction is 20-100°C; the reaction time is 1-10 hours.

3. The production method according to claim 1 or 2, wherein In step (2), the second polyurethane is selected from thermoplastic polyurethane, wherein the thermoplastic polyurethane is polyester-type or polyether-type thermoplastic polyurethane; And / or, in step (2), the melt index of the second polyurethane is 5-150 g / 10 min; And / or, in step (2), the mass of the first polyurethane grafted isocyanate copolymer accounts for 0.5-20 wt% of the total mass of the first polyurethane grafted isocyanate copolymer and the second polyurethane; And / or, in step (2), the reaction of the first thermoplastic polyurethane grafted isocyanate copolymer and the second thermoplastic polyurethane is carried out in a heated molten state without the addition of solvent; And / or, in step (2), the temperature of the reaction is 100-200°C; the reaction time is 5 minutes to 10 hours.

4. The modified polyurethane with a long-chain branched structure prepared by the method according to any one of claims 1-3.

5. The modified polyurethane with a long-chain branched structure according to claim 4, wherein the softening point of the modified polyurethane with a long-chain branched structure is 60-130℃; the Shore hardness is 60-95A; and the melt flow index is 2-150g / 10min.

6. A process for the preparation of a modified polyurethane foam, wherein, The method includes the following steps: After drying the modified polyurethane with a long-chain branched structure as described in claim 4 or 5, it is added to an autoclave and carbon dioxide is injected. The autoclave is heated to the foaming temperature, held for a certain period of time, and then depressurized to atmospheric pressure and cooled to room temperature to obtain the modified polyurethane foam material.

7. The production method according to claim 6, wherein The foaming temperature is 130-250℃; And / or, the pressure of the carbon dioxide is 2-20 MPa; And / or, the duration of the stay is 1-8 hours; And / or, the rate of pressure relief is 2-20 MPa / 60 s.

8. The modified polyurethane foam material prepared by the method of claim 6 or 7.

9. The modified polyurethane foam material according to claim 8, wherein, The expansion ratio of the modified polyurethane foam material is in the range of 25-30 times; And / or, the thermal conductivity of the modified polyurethane foam material is 0.020-0.030 W / (m·K).

10. Use of the modified polyurethane foam material according to claim 8 or 9 in the field of clothing thermal insulation.