Bio-based polyurethane as well as preparation method and application thereof

Abstract

The invention discloses bio-based polyurethane as well as a preparation method and application thereof, and belongs to the technical field of polyurethane. The bio-based polyurethane is prepared from bio-based silicon-based polyester polyol, diisocyanate and a bio-based chain extender, wherein the molar ratio of the bio-based silicon-based polyester polyol to the diisocyanate to the bio-based chain extender is 1.0: (3.0-5.0): (2.0-4.0); wherein the bio-based silicon-based polyester polyol is prepared by taking bio-based dibasic acid and single-ended dihydroxy siloxane as raw materials, and carrying out esterification reaction on the bio-based dibasic acid and the single-ended dihydroxy siloxane. In the bio-based polyurethane, siloxane antifouling groups are suspended on side chains of polyurethane macromolecules, so that the bio-based polyurethane is endowed with excellent antifouling and hydrophobic properties; the mechanical property of polyurethane is good, the compatibility of siloxane and polyurethane is improved, and the polyurethane slurry has good pigment dispersion stability. In general, the comprehensive performance of the bio-based polyurethane is excellent, and the bio-based polyurethane has important economic and application significance for obtaining high-quality polyurethane products.

Description

Technical Field

[0001] The present application belongs to the technical field of polyurethane, and specifically relates to a bio-based polyurethane and a preparation method and application thereof. Background Art

[0002] Bio-based polyurethane is a type of polyurethane material that uses cellulose, starch, vegetable oil and their derivatives to prepare biopolyols. It can reduce the consumption of petrochemical resources and environmental pollution, and lower the cost of preparation and application.

[0003] In practical applications, polyurethane coatings commonly used in construction, automobiles, homes and other fields need to have excellent adhesion, hardness or toughness, wear resistance and chemical resistance. However, since polyurethane molecules have high polarity and strong adsorption, they are easily contaminated and difficult to clean, so polyurethane needs to be modified to achieve surface protection and anti-fouling effects.

[0004] In general, the wetting ability of pollutants to stick to their surfaces can be reduced by generating complex surface microstructures or introducing low surface energy chemistry, such as simulating the surface structure of lotus leaves or using silicon-based or fluorine-based components as lubricating ingredients. Although fluoride can give coatings good antifouling properties, its bioaccumulation is a big environmental problem. The main chain of silicon is a linear structure of silicon and oxygen, and the side groups are decorated with a large number of non-polar methyl groups, which makes the silicon component have low roughness and glass transition temperature, good flexibility at low temperatures, and its low surface energy structural characteristics can reduce the adhesion of pollutants to the surface, so it is an environmentally friendly lubricating component.

[0005] However, most of the current silicon-based polyurethanes are introduced into the ends of the macromolecular chains by end-capping, but the content of silicon introduced by the end-capping reaction is limited. Alternatively, siloxanes and the like are directly introduced into the polyurethane main chain as diols. The mobility of silicon groups in this structure is limited, which in turn affects its antifouling activity. Moreover, when siloxanes and the like are directly used as polyols to react with isocyanates, there will be unreacted free monomer silicones, which have poor compatibility with polyurethanes and are prone to phase separation problems. Phase separation has a significant impact on the transparency of polyurethane coatings and the stable dispersion of pigments.

[0006] Therefore, the development of new bio-based polyurethanes is of great significance and great economic value. Summary of the invention

[0007] In view of this, the primary purpose of the present application is to provide a bio-based polyurethane, which is prepared based on bio-based silicon-based polyester polyols, and suspends siloxane anti-fouling groups on the side chains of polyurethane macromolecules, thereby giving the bio-based polyurethane excellent anti-fouling and hydrophobic properties, and the polyurethane slurry formed therefrom has excellent pigment dispersion stability.

[0008] In order to achieve the above objectives, this application adopts the following technical solutions: In one aspect of the present application, a bio-based polyurethane is disclosed, which is prepared from a bio-based silicon-based polyester polyol, a diisocyanate, and a bio-based chain extender in a molar ratio of 1.0:(3.0-5.0):(2.0-4.0); The bio-based silicon-based polyester polyol is prepared by esterification reaction using bio-based dibasic acid and single-terminal dihydroxysiloxane as raw materials.

[0009] Another aspect of the present application discloses a method for preparing the bio-based polyurethane as described above, comprising the following steps: The bio-based silicon-based polyester polyol and the bio-based chain extender are mixed and dispersed uniformly at 30-50°C, diisocyanate and a catalyst are added, reacted at 60-80°C for 6-10 hours, diluted and adjusted to a solid content of 25±1% and a viscosity of 30-60 Pa·s / 25°C to obtain a bio-based polyurethane.

[0010] Another aspect of the present application discloses a polyurethane film comprising the bio-based polyurethane described above.

[0011] Beneficial effects of this application: The bio-based polyurethane in this application is prepared from bio-based silicon-based polyester polyols and bio-based diols, wherein the bio-based silicon-based polyester polyols are derived from dibasic acids of renewable biomass and silicon oxygen resources with rich mineral deposits, and have significant environmental protection and cost advantages. The single-ended dihydroxy siloxane is first prepared into a bio-based silicon-based polyester polyol, and a water-repellent and antifouling siloxane chain is suspended on the side chain. The main chain of the obtained bio-based silicon-based polyester polyol has reactive hydroxyl groups at both ends, and the bio-based polyurethane is prepared by using it to obtain excellent antifouling and water-repellent effects; and the bio-based silicon-based polyester polyol is liquid at room temperature, and has obvious compatibility advantages. At the same time, the bio-based polyurethane can give the polyurethane slurry good pigment dispersion stability, and the mechanical properties of the polyurethane are improved; a surface brush-like antifouling structure is formed in the polyurethane coating, and the antifouling effect is better than that of the double-ended single hydroxyl polyurethane coating. DETAILED DESCRIPTION

[0012] The following will clearly and completely describe the implementation methods of the present application. The technical solutions in the implementation methods described below are exemplary and are only possible technical implementations of the present application, not all possible implementations. Those skilled in the art can fully combine the implementation methods of the present application to obtain other implementation methods without creative work, and these implementation methods are also within the scope of protection of the present application.

[0013] The first aspect of the present application discloses a bio-based polyurethane, which is prepared from a bio-based silicon-based polyester polyol, a diisocyanate and a bio-based chain extender in a molar ratio of 1.0:(3.0-5.0):(2.0-4.0).

[0014] The bio-based polyurethane in the present application is prepared by reacting bio-based silicon-based polyester polyols and bio-based chain extenders with diisocyanates, wherein the bio-based silicon-based polyester polyols and bio-based chain extenders are both raw material components derived from renewable biomass, and therefore can reduce petrochemical resource consumption and environmental pollution, and reduce the cost of preparation and application of polyurethane.

[0015] In this application, bio-based silicon-based polyester polyol is used as the raw material of bio-based polyurethane, and a water-repellent and anti-fouling siloxane chain is suspended on the side chain. The siloxane chain is a linear structure of silicon and oxygen, and the side group is decorated with a large number of non-polar methyl groups, so that the silicon component has low roughness and glass transition temperature, and has good flexibility at low temperatures. Its structural characteristics of low surface energy can reduce the adhesion of pollutants to the surface. In this application, the siloxane chain is suspended on the side chain of the polyurethane macromolecule, so it has better mobility, can more effectively exert its anti-fouling effect, and give the bio-based polyurethane excellent anti-fouling and water-repellent effects. At the same time, the bio-based polyurethane can also give the polyurethane slurry good pigment dispersion stability, overcome the problem of phase separation, and improve the mechanical properties.

[0016] The composition of bio-based polyurethane will be described in detail below.

[0017] <Bio-based Silicone Polyester Polyol> In the present application, the bio-based silicon-based polyester polyol is prepared by esterification reaction using bio-based dibasic acid and single-terminal dihydroxy siloxane as raw materials.

[0018] The bio-based dibasic acid is an organic compound containing two carboxyl groups (—COOH) in its molecular structure, and is extracted and prepared from renewable biomass (such as plants, etc.). Specific examples include at least one of bio-based succinic acid and bio-based sebacic acid, but are not limited thereto. In some examples, the bio-based dibasic acid is bio-based succinic acid.

[0019] In the present application, the general structural formula of the single-terminal dihydroxy siloxane is as follows: ; Wherein, n is the number of repeating units of siloxane, which is an integer of 1 to 10, and R' is an alkane group.

[0020] In some examples, the number average molecular weight of the single-ended dihydroxy siloxane is 290-1000.

[0021] It is understandable that in the raw material composition of bio-based silicon-based polyester polyol, its specific amount is not particularly limited and can be determined by experimental methods according to the target object. In some examples, the weight percentages of the components required to prepare the bio-based silicon-based polyester polyol are: 75-95% single-end dihydroxy siloxane, 5-25% bio-based dibasic acid, 0-0.05% antioxidant, and 0-0.02% catalyst. Among them, antioxidants and catalysts are added as needed, and their specific types are not particularly limited, and common types in the art can be used. In some specific examples, the antioxidant is UHS-8080LF and the catalyst is tetraisopropyl titanate (TPT), but it is not limited to this.

[0022] The preparation of the bio-based silicon-based polyester polyol described in this application can be carried out based on the conventional polyol preparation process in the art. The specific process parameters and conditions can be determined by experiments, and those skilled in the art have such capabilities. In some examples, the preparation method of the bio-based silicon-based polyester polyol includes the following steps: S1, taking single-ended dihydroxy siloxane, bio-based dibasic acid and antioxidant, stirring and mixing them evenly, and then introducing protective gas; S2, controlling the top temperature of the distillation tower not to exceed 100°C, gradually heating to 205°C, and after detecting that the acid value is reduced to 10mgKOH / g, adding a catalyst, continuing the reaction, and starting a vacuum pumping; S3. When the acid value is less than 1.0 mgKOH / g, set the reactor temperature to 220-240°C and start secondary vacuuming; S4. After 5-10 hours of ester exchange reaction, the water and small molecule silicone oil in the system are extracted, and when the acid value is ≤0.3 mgKOH / g, the hydroxyl value is 56±4 mgKOH / g, the water content is ≤0.02%, and the viscosity reaches 400~600 mPa·s / 75°C, the bio-based silicon-based polyester polyol is obtained.

[0023] It is understandable that the protective gas is a gas known in the art that is inert or inactive to reactions, raw materials and products, such as at least one of rare gases (such as helium, argon, etc.) or nitrogen, which will not be elaborated here.

[0024] <Bio-based chain extenders> In the present application, the bio-based chain extender refers to a C2-C4 bio-based diol, which is an organic compound containing two hydroxyl groups (—OH) in the molecular structure and obtained by biological fermentation, natural oil modification or sugar conversion. Specific examples include at least one of bio-based 1,3-propylene glycol (PDO), bio-based 1,4-butanediol (BDO), and bio-based ethylene glycol, but are not limited thereto. In some examples, the bio-based chain extender is 1,3-propylene glycol (PDO).

[0025] <Diisocyanate> In the present application, the diisocyanate is an organic compound having two isocyanate groups (-NCO) in its molecular structure, which is a common raw material component of polyurethane. Specific examples include but are not limited to at least one of toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI).

[0026] The second aspect of the present application discloses a method for preparing the bio-based polyurethane as described above, which can be carried out with reference to the polyurethane preparation process well known in the art, and the specific process conditions and parameters can be adjusted or optimized as needed.

[0027] In some examples, the method for preparing the bio-based polyurethane comprises the following steps: The bio-based silicon-based polyester polyol and the bio-based chain extender are mixed and dispersed uniformly at 30-50°C, diisocyanate and a catalyst are added, reacted at 60-80°C for 6-10 hours, diluted and adjusted to a solid content of 25±1% and a viscosity of 30-60 Pa·s / 25°C to obtain a bio-based polyurethane.

[0028] The catalyst is a commonly used component in the preparation of polyurethane in the art, and is not particularly limited. Common examples include amine catalysts, metal catalysts (such as tin, bismuth) or environmentally friendly catalysts. In some specific examples, the catalyst used is MB20. There is no special requirement for the amount of the catalyst, and it can be added according to the conventional amount.

[0029] In the present application, the dilution and viscosity adjustment are carried out using solvents well known in the art, and specific examples include dimethylformamide, etc., but are not limited thereto.

[0030] The third aspect of the present application discloses a polyurethane film, which refers to a polymer film or coating material made of polyurethane. In the present application, it refers to a polymer film or coating material made of the bio-based polyurethane described above. It is understood that other functional additives or components for optimizing its performance may be added to the polyurethane film as needed to give it corresponding properties, and there is no special limitation here.

[0031] The following are specific embodiments of the present application. It should be noted that the following specific embodiments are only for illustrative purposes and do not limit the scope of the present application in any way.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0033] In addition, unless otherwise specified, methods without specific conditions or steps are conventional methods, and the reagents and materials used are all commercially available.

[0034] The main raw materials used in the following examples and comparative examples are as follows: Bio-based 1,3-propanediol (PDO), DuPont Biotech.

[0035] Bio-based succinic acid, Shandong Landian Biotechnology Co., Ltd.

[0036] Single-ended dihydroxy siloxane SL-472X, Hangzhou Chongyao Technology Development Co., Ltd., its molecular weight can be customized according to needs.

[0037] Antioxidant UHS-8080LF, Yuanhe Industrial Co., Ltd.

[0038] Example 1 This embodiment provides a method for preparing a bio-based silicon-based polyester polyol, and the specific steps are as follows: Single-end dihydroxy siloxane, bio-based dibasic acid, and antioxidant UHS-8080LF were added to the reactor, stirred and mixed evenly, and then nitrogen was introduced; the top temperature of the distillation tower was controlled not to exceed 100°C, and after gradient heating to 205°C, the acid value was detected to be reduced to 10 mgKOH / g, and then the catalyst TPT was added, the reaction was continued, and the first vacuum was started; when the acid value was less than 1.0 mgKOH / g, the reactor temperature was set to 225°C, and the second vacuum was started; after 7 hours of transesterification reaction, the water and small molecule silicone oil in the system were pumped out to obtain bio-based silicon-based polyester polyol, whose acid value was 0.29 mgKOH / g, hydroxyl value was 56.12 mgKOH / g, water content was 0.017%, and viscosity was 470 Pa·s / 75°C. The raw material composition and dosage are shown in Table 1.

[0039] Example 2 This embodiment provides a method for preparing a bio-based silicon-based polyester polyol, and the specific steps are as follows: Add single-end dihydroxy siloxane, bio-based dibasic acid, and antioxidant UHS-8080LF into the reactor, stir and mix evenly, and then introduce nitrogen; control the top temperature of the distillation tower not to exceed 100°C, and after gradient heating to 205°C, detect that the acid value is reduced to 10mgKOH / g, add catalyst TPT, continue the reaction, and start the first vacuum pumping; when the acid value is less than 1.0mgKOH / g, set the reactor temperature to 225°C, and start the second vacuum pumping; after 7h of ester exchange reaction, remove the water and small molecule silicone oil in the system to obtain bio-based silicon-based polyester polyol, whose acid value is 0.23mgKOH / g, hydroxyl value is 56.32mgKOH / g, water content is 0.019%, and viscosity is 480Pa·s / 75°C. Its raw material composition and dosage are shown in Table 1.

[0040] Example 3 This embodiment provides a method for preparing a bio-based silicon-based polyester polyol, and the specific steps are as follows: Single-end dihydroxy siloxane, bio-based dibasic acid, and antioxidant UHS-8080LF were added to the reactor, stirred and mixed evenly, and then nitrogen was introduced; the top temperature of the distillation tower was controlled not to exceed 100°C, and after gradient heating to 205°C, the acid value was detected to be reduced to 10 mgKOH / g, and then the catalyst TPT was added, the reaction was continued, and the first vacuum was started; when the acid value was less than 1.0 mgKOH / g, the reactor temperature was set to 225°C, and the second vacuum was started; after 7 hours of transesterification reaction, the water and small molecule silicone oil in the system were pumped out to obtain bio-based silicon-based polyester polyol, whose acid value was 0.25 mgKOH / g, hydroxyl value was 55.96 mgKOH / g, water content was 0.016%, and viscosity was 470 Pa·s / 75°C. The raw material composition and dosage are shown in Table 1.

[0041] Table 1 Raw material composition and dosage of bio-based silicon-based polyester polyols in Examples 1-3

[0042] Example 4 This embodiment provides a method for preparing bio-based polyurethane, and the specific steps are as follows: The bio-based silicon-based polyester polyol (100 g) prepared in Example 1 and the bio-based chain extender 1,3-propylene glycol (7.6 g) were mixed and dispersed uniformly at 35° C., diisocyanate MDI (37.5 g) and catalyst MB20 (57 ppm) were added, and the mixture was reacted at 65° C. for 8 hours. The solvent dimethylformamide was used to dilute and adjust the viscosity to obtain a bio-based polyurethane with a solid content of 25% and a viscosity of 49 Pa·s / 25° C.

[0043] Example 5 This embodiment provides a method for preparing bio-based polyurethane, and the specific steps are as follows: The bio-based silicon-based polyester polyol (100 g) prepared in Example 1 and the bio-based chain extender 1,3-propylene glycol (15.2 g) were mixed and dispersed uniformly at 35° C., diisocyanate MDI (62.5 g) and catalyst MB20 (70 ppm) were added, and the mixture was reacted at 65° C. for 8 hours. The solvent dimethylformamide was used to dilute and adjust the viscosity to obtain a bio-based polyurethane with a solid content of 25% and a viscosity of 53 Pa·s / 25° C.

[0044] Example 6 This embodiment provides a method for preparing bio-based polyurethane, and the specific steps are as follows: The bio-based silicon-based polyester polyol (100 g) prepared in Example 2 and the bio-based chain extender 1,3-propylene glycol (7.6 g) were mixed and dispersed uniformly at 35° C., diisocyanate MDI (37.5 g) and catalyst MB20 (57 ppm) were added, and the mixture was reacted at 65° C. for 8 hours. The solvent dimethylformamide was used to dilute and adjust the viscosity to obtain a bio-based polyurethane with a solid content of 25% and a viscosity of 52 Pa·s / 25° C.

[0045] Example 7 This embodiment provides a method for preparing bio-based polyurethane, and the specific steps are as follows: The bio-based silicon-based polyester polyol (100 g) prepared in Example 2 and the bio-based chain extender 1,3-propylene glycol (15.2 g) were mixed and dispersed uniformly at 35° C., diisocyanate MDI (62.5 g) and catalyst MB20 (70 ppm) were added, and the mixture was reacted at 65° C. for 8 hours. The solvent dimethylformamide was used to dilute and adjust the viscosity to obtain a bio-based polyurethane with a solid content of 25% and a viscosity of 49 Pa·s / 25° C.

[0046] Example 8 This embodiment provides a method for preparing bio-based polyurethane, and the specific steps are as follows: The bio-based silicon-based polyester polyol (100 g) prepared in Example 3 and the bio-based chain extender 1,3-propylene glycol (7.6 g) were mixed and dispersed uniformly at 35° C., diisocyanate MDI (37.5 g) and catalyst MB20 (57 ppm) were added, and the mixture was reacted at 65° C. for 8 hours. The solvent dimethylformamide was used to dilute and adjust the viscosity to obtain a bio-based polyurethane with a solid content of 25% and a viscosity of 56 Pa·s / 25° C.

[0047] Example 9 This embodiment provides a method for preparing bio-based polyurethane, and the specific steps are as follows: The bio-based silicon-based polyester polyol (100 g) prepared in Example 3 and the bio-based chain extender 1,3-propylene glycol (15.2 g) were mixed and dispersed uniformly at 35° C., diisocyanate MDI (62.5 g) and catalyst MB20 (70 ppm) were added, and the mixture was reacted at 65° C. for 8 hours. The solvent dimethylformamide was used to dilute and adjust the viscosity to obtain a bio-based polyurethane with a solid content of 25% and a viscosity of 48 Pa·s / 25° C.

[0048] Table 2 Bio-based polyurethane raw material components and amounts in Examples 4-9

[0049] Comparative Example 1 This comparative example discloses another method for preparing bio-based polyurethane, which adopts the same implementation as Example 4, except that: a double-terminal monohydroxy silicone oil with a molecular weight of 2000 is used to replace the bio-based silicon-based polyester polyol. Other raw material compositions and process conditions are the same as those in Example 4.

[0050] Comparative Example 2 This comparative example discloses another method for preparing bio-based polyurethane, which adopts the same implementation as Example 4, except that: a single-terminal dihydroxy silicone oil with a molecular weight of 2000 is used to replace the bio-based silicon-based polyester polyol. Other raw material compositions and process conditions are the same as those in Example 4.

[0051] Comparative Example 3 This comparative example discloses another method for preparing bio-based polyurethane, and the specific steps are as follows: Single-end dihydroxy siloxane (molecular weight 2000, 50g) was first mixed with isocyanate MDI (10g) at 35°C and dispersed evenly, and reacted at 65°C for 1h to obtain a silicone polyurethane prepolymer, and then the bio-based chain extender 1,3-propylene glycol (7.6g) and bio-based polyester polyol (molecular weight 2000, 50g) were added and mixed and dispersed evenly. Finally, diisocyanate MDI (27.5g) and catalyst MB20 (57ppm) were added, and the mixture was reacted at 65°C for 8 hours. The solvent dimethylformamide was used to dilute and adjust the viscosity to obtain a bio-based polyurethane with a solid content of 25% and a viscosity of 47Pa·s / 25°C.

[0052] Performance Testing 1. The bio-based polyurethanes in Examples 4-9 and Comparative Examples 1-3 were made into polyurethane films, that is, the bio-based polyurethanes in Examples 4-9 and Comparative Examples 1-3 were scraped on a glass plate, treated in an oven at 130°C for 3 hours to prepare a dry film with a thickness of 0.1 mm, cooled and placed at room temperature for 72 hours, and then tested for mechanical properties and antifouling and water repellency. The test results are shown in Table 3.

[0053] Table 3 Test results of mechanical properties, antifouling and water repellency of polyurethane films

[0054] Among them, each test item is carried out according to the following method: (1) The tensile properties test was carried out according to the methods of GB / T1040.1-2018 and GB / T1040.3-2006.

[0055] (2) The water contact angle was measured according to GB / T 30693-2014.

[0056] (3) Antifouling performance test: Smear a 30 mm square stain on a 200 mm square sample, place it at room temperature for 24 hours, wipe it vigorously with a napkin (60 times within 2 minutes), and judge the grade according to GB / T 251-2008. The staining agents include ketchup, gasoline engine oil, freshly squeezed orange juice, instant coffee, tea and red wine.

[0057] As shown in Table 3, Examples 4 to 9 use single-end dihydroxy siloxane and bio-based succinate esterification reaction to prepare polyols, and the reactive hydroxyl groups are located at both ends of the main chain, and the side chains are suspended with water-repellent and antifouling siloxane chains, which are liquid at room temperature and have obvious compatibility advantages. When it is used as a polyol to prepare bio-based polyurethane, the mechanical properties are improved, and the bio-based silicon-based polyester polyol is introduced into the polyurethane to form a surface brush-like antifouling structure, with a water contact angle of more than 113︒, and excellent antifouling and water-repellent effect. In general, the bio-based polyurethane in this application has excellent antifouling and water-repellent properties, high mechanical properties, and good comprehensive properties. However, in Comparative Examples 1, 2 and 3, since the hydroxy siloxane directly reacts with isocyanate without modification, there is an obvious phase separation problem.

[0058] 2. The bio-based polyurethanes in Examples 4-9 and Comparative Examples 1-3 were prepared into slurries according to the following method: Weigh 120 g of bio-based polyurethane, 60 g of DMF solvent, 20 g of PU white, 0.5 g of PU black, 0.5 g of PU yellow, 0.5 g of PU red and 1 g of TB030 blue, stir in a blender for 5 minutes to disperse evenly, and obtain a slurry.

[0059] The prepared slurry was allowed to stand at room temperature for the same period of time to observe the uniformity of the pigment at different time points, as well as whether it was flocculated, floated, or layered. The results are shown in Table 4.

[0060] Table 4 Polyurethane slurry stability test results

[0061] As can be seen from Table 4, when a polyol is prepared by reacting a single-ended dihydroxy siloxane with a bio-based succinate and used as a polyol to prepare a bio-based polyurethane, the compatibility of the siloxane and the polyurethane can be improved, and the polyurethane slurry can be given good pigment dispersion stability, which is of great significance to the color stability of the silicon-based polyurethane during subsequent processing.

[0062] It should be noted that the purpose of this application can be achieved when the experimental process meets the following conditions: As for the bio-based dibasic acid, it can also be bio-based sebacic acid.

[0063] The temperature for preparing bio-based silicon-based diols may be 220-240°C, specifically any temperature of 220°C, 225°C, 230°C, 235°C, 240°C, etc., or a temperature between any two temperature ranges.

[0064] As for the bio-based chain extender, it can also be bio-based 1,4-butanediol or ethylene glycol.

[0065] As for the reaction conditions of bio-based polyurethane, the bio-based silicon-based polyester polyol and the bio-based chain extender are preferably mixed and evenly dispersed at 30-50°C, and can also be any temperature of 30°C, 35°C, 40°C, 45°C or 50°C, or a temperature between any two temperature ranges; after adding diisocyanate and catalyst, the reaction is preferably carried out at 60-80°C for 6-10 hours, and the temperature can be any temperature of 60°C, 65°C, 70°C, 75°C or 80°C, or a temperature between any two temperature ranges, and the time can be adjusted as needed, for example, 6h, 7h, 8h, 9h or 10h, etc.

[0066] For the above process parameters, those skilled in the art can make appropriate selections according to actual needs, all of which can achieve the purpose of this application.

[0067] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A bio-based polyurethane, characterized in that: It is prepared from bio-based silicon-based polyester polyol, diisocyanate and bio-based chain extender in a molar ratio of 1.0:(3.0-5.0):(2.0-4.0); The bio-based silicon-based polyester polyol is prepared by esterification reaction using bio-based dibasic acid and single-terminal dihydroxysiloxane as raw materials.

2. The bio-based polyurethane according to claim 1, characterized in that The diisocyanate is at least one of toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate.

3. The bio-based polyurethane according to claim 1, characterized in that The bio-based chain extender is at least one of bio-based 1,3-propylene glycol, bio-based 1,4-butanediol, and bio-based ethylene glycol.

4. The bio-based polyurethane according to claim 1, characterized in that The bio-based dibasic acid is at least one of bio-based succinic acid and bio-based sebacic acid.

5. The bio-based polyurethane according to claim 1, characterized in that The general structural formula of the single-ended dihydroxy siloxane is as follows: ； Wherein, n is an integer of 1 to 10, and R' is an alkane group.

6. The bio-based polyurethane according to claim 1, characterized in that The number average molecular weight of the single-ended dihydroxysiloxane is 290-1000.

7. The bio-based polyurethane according to claim 1, characterized in that The weight percentages of the components required for preparing the bio-based silicon-based polyester polyol are: 75-95% of single-end dihydroxy siloxane, 5-25% of bio-based dibasic acid, 0-0.05% of antioxidant, and 0-0.02% of catalyst.

8. The bio-based polyurethane according to claim 1, characterized in that The preparation method of the bio-based silicon-based polyester polyol comprises the following steps: S1, taking single-ended dihydroxy siloxane, bio-based dibasic acid and antioxidant, stirring and mixing them evenly, and then introducing protective gas; S2, controlling the top temperature of the distillation tower not to exceed 100°C, gradually heating to 205°C, and after detecting that the acid value is reduced to 10mgKOH / g, adding the catalyst, continuing the reaction, and starting a vacuum pumping; S3. When the acid value is less than 1.0 mgKOH / g, set the reactor temperature to 220-240°C and start secondary vacuuming; S4. After 5-10 hours of ester exchange reaction, the water and small molecule silicone oil in the system are extracted, and when the acid value is ≤0.3 mgKOH / g, the hydroxyl value is 56±4 mgKOH / g, the water content is ≤0.02%, and the viscosity reaches 400~600 mPa·s / 75°C, the bio-based silicon-based polyester polyol is obtained.

9. A method for preparing the bio-based polyurethane according to any one of claims 1 to 8, characterized in that: The following steps are involved: The bio-based silicon-based polyester polyol and the bio-based chain extender are mixed and dispersed uniformly at 30-50°C, diisocyanate and a catalyst are added, reacted at 60-80°C for 6-10 hours, diluted and adjusted to a solid content of 25±1% and a viscosity of 30-60 Pa·s / 25°C to obtain a bio-based polyurethane.

10. A polyurethane film, characterized in that: Contains the bio-based polyurethane according to any one of claims 1 to 8.

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