A bio-based polyurethane and its preparation method and application

Abstract

The present application discloses a bio-based polyurethane and its preparation method and application, belonging to the technical field of polyurethanes. The bio-based polyurethane is prepared from a bio-based silicon-based polyester polyol, a diisocyanate and a bio-based chain extender with a molar ratio of 1.0:(3.0-5.0):(2.0-4.0); wherein, the bio-based silicon-based polyester polyol is prepared from a bio-based dibasic acid and a mono-terminal dihydroxy siloxane through an esterification reaction. In this bio-based polyurethane, the siloxane antifouling group is suspended on the side chain of the polyurethane macromolecule, endowing the bio-based polyurethane with excellent antifouling and hydrophobic properties; the polyurethane has good mechanical properties, and the compatibility between the siloxane and the polyurethane is improved, and the polyurethane slurry has good pigment dispersion stability. Generally speaking, the comprehensive performance of this bio-based polyurethane is excellent, which has important economic and application significance for obtaining high-quality polyurethane products.

Description

Technical Field

[0001] This application belongs to the technical field of polyurethanes, and particularly relates to a bio-based polyurethane and its preparation method and application. Background Art

[0002] Bio-based polyurethanes are a type of polyurethane material that applies cellulose, starch, vegetable oils and their derivatives to the preparation of bio-polyols, which can reduce the consumption of petrochemical resources and environmental pollution, and reduce the costs of preparation and application.

[0003] In practical applications, polyurethane coatings commonly used in multiple fields such as construction, automobiles, and household furnishings need to have excellent adhesion, hardness or toughness, wear resistance, and chemical resistance. However, due to the high polarity of polyurethane molecules, they have strong adsorption properties, are easily contaminated, and are not conducive to cleaning. Therefore, it is necessary to modify polyurethanes to achieve the effects of surface protection and anti-fouling.

[0004] Generally speaking, it is possible to reduce the wetting ability of pollutants adhering to its surface by generating complex surface microstructures or introducing low surface energy chemistry, such as mimicking the surface structure of lotus leaves or using silicon-based or fluorine-based components as lubricating components. Although fluorides can endow the coating with good anti-fouling performance, their bioaccumulation is a major environmental problem. The main chain of silicon is a linear structure of silicon oxygen, and the side groups are decorated with a large number of non-polar methyl groups, making the silicon component have low roughness and glass transition temperature, and have good flexibility at low temperatures. The structural characteristics of its low surface energy can reduce the adhesion of pollutants to the surface, so it is an environmentally friendly lubricating component.

[0005] However, currently, for silicon-based polyurethanes, most of them introduce silicon-based groups into the ends of macromolecular chains through capping, but the amount of silicon-based groups introduced by the capping reaction is limited. Or siloxanes, etc. are directly introduced into the polyurethane main chain as diols. The mobility of the silicon-based groups in this structure is limited, which in turn affects their anti-fouling activity; and when siloxanes, etc. are directly used as polyols to react with isocyanates, there will be unreacted free monomer organosilicons, and their compatibility with polyurethanes is poor, and phase separation is likely to occur. Phase separation has a significant impact on the transparency of polyurethane coatings, the stable dispersion of pigments, etc.

[0006] Therefore, developing new bio-based polyurethanes has important significance and great economic value. Summary of the Invention

[0007] In view of this, the primary object of this 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 endowing the bio-based polyurethane with excellent anti-fouling and hydrophobic properties, and the formed polyurethane slurry has excellent pigment dispersion stability.

[0008] To achieve the above object, the present application adopts the following technical solutions:

[0009] One 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 with a molar ratio of 1.0: (3.0 - 5.0): (2.0 - 4.0);

[0010] Wherein, the bio-based silicon-based polyester polyol is prepared by an esterification reaction using a bio-based dibasic acid and a mono-terminal dihydroxy siloxane as raw materials.

[0011] Another aspect of the present application discloses a method for preparing the bio-based polyurethane as described above, comprising the following steps:

[0012] Mix and disperse the bio-based silicon-based polyester polyol and the bio-based chain extender evenly at 30 - 50 °C, add the diisocyanate and a catalyst, react at 60 - 80 °C for 6 - 10 hours, dilute and adjust the viscosity to a solid content of 25 ± 1% and a viscosity of 30 - 60 Pa·s / 25 °C to obtain the bio-based polyurethane.

[0013] Another aspect of the present application discloses a polyurethane film containing the bio-based polyurethane as described above.

[0014] Advantages of the present application:

[0015] The bio-based polyurethane in the present application is prepared from a bio-based silicon-based polyester polyol and a bio-based diol. Among them, the bio-based silicon-based polyester polyol is derived from dibasic acids of renewable biomass and silicon oxygen resources with rich reserves, having significant environmental protection and cost advantages. First, the mono-terminal dihydroxy siloxane is prepared into a bio-based silicon-based polyester polyol, and a water-repellent and stain-resistant siloxane chain is suspended on the side chain. The obtained bio-based silicon-based polyester polyol has reactive hydroxyl groups at both ends of the main chain. Using it to prepare the bio-based polyurethane can obtain excellent anti-fouling and water-repellent effects; and this bio-based silicon-based polyester polyol is liquid at room temperature, having obvious compatibility advantages. At the same time, this bio-based polyurethane can endow the polyurethane slurry with good pigment dispersion stability, and the mechanical properties of the polyurethane are improved; a surface brush-like anti-fouling structure is formed in the polyurethane coating, and the anti-fouling effect is better than that of a polyurethane coating with double-terminal mono-hydroxy groups. Specific Embodiments

[0016] The embodiments of the present application will be clearly and completely described below. The technical solutions in the following described embodiments are exemplary and only possible technical implementations of the present application, not all possible implementations. Those skilled in the art can fully combine the embodiments of the present application to obtain other embodiments without creative labor, and these embodiments are also within the protection scope of the present application.

[0017] 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).

[0018] The bio-based polyurethane in the present application is prepared by reacting a bio-based silicon-based polyester polyol and a bio-based chain extender with a diisocyanate. Among them, both the bio-based silicon-based polyester polyol and the bio-based chain extender are raw material components derived from renewable biomass. Therefore, it can reduce the consumption of petrochemical resources and environmental pollution, and reduce the cost of polyurethane preparation and application.

[0019] In the present application, the bio-based silicon-based polyester polyol is used as a raw material for the bio-based polyurethane, and a water-repellent and stain-resistant siloxane chain is suspended on the side chain. The siloxane chain is a linear structure of silicon and oxygen, and the side groups are decorated with a large number of non-polar methyl groups, making the silicon component have a low roughness and a glass transition temperature, and having good flexibility at low temperatures. Its low surface energy structural characteristics can reduce the adhesion of pollutants to the surface. In the present application, the siloxane chain is suspended on the side chain of the polyurethane macromolecule, so it has better mobility and can more effectively exert its anti-fouling effect, endowing the bio-based polyurethane with excellent anti-fouling and water-repellent effects. At the same time, the bio-based polyurethane can also endow the polyurethane slurry with good pigment dispersion stability, overcome the problem of phase separation, and improve the mechanical properties.

[0020] Next, the composition of the bio-based polyurethane will be specifically described.

[0021] <Bio-based silicon-based polyester polyol>

[0022] In the present application, the bio-based silicon-based polyester polyol is prepared by an esterification reaction using a bio-based dibasic acid and a mono-terminal dihydroxy siloxane as raw materials.

[0023] Among them, the bio-based dibasic acid is a class of organic compounds containing two carboxyl groups (—COOH) in the molecular structure, and it is prepared by extracting 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.

[0024] In the present application, the structural general formula of the mono-terminal dihydroxy siloxane is as follows:

[0025] ;

[0026] Among them, n is the number of repeating units of the siloxane, which is an integer from 1 to 10, and R’ is an alkyl group.

[0027] In some examples, the number average molecular weight of the mono-terminal dihydroxy siloxane is 290 - 1000.

[0028] It is understandable that in the raw material composition of the bio-based silicon-based polyester polyol, its specific dosage is not particularly limited and can be determined by experimental methods according to the target product. In some examples, the weight percentages of the components required for preparing the bio-based silicon-based polyester polyol are as follows: mono-terminal dihydroxy siloxane 75-95%, bio-based dibasic acid 5-25%, antioxidant 0-0.05%, catalyst 0-0.02%. Among them, the antioxidant and the catalyst 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 tetra-isopropyl titanate (TPT), but it is not limited thereto.

[0029] 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, and the specific process parameters and conditions can be determined by experimental means, 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:

[0030] S1. Take mono-terminal dihydroxy siloxane, bio-based dibasic acid and antioxidant, stir and mix them evenly, and then introduce a protective gas;

[0031] S2. Control the top temperature of the distillation column not to exceed 100 °C, gradually heat up to 205 °C, after detecting that the acid value drops to 10 mgKOH / g, add the catalyst, continue the reaction, and start the first vacuum pumping;

[0032] S3. When the acid value is less than 1.0 mgKOH / g, set the reaction kettle temperature at 220-240 °C and start the second vacuum pumping;

[0033] S4. After the transesterification reaction for 5-10 h, remove the water and small molecule silicone oil in the system. When the acid value ≤ 0.3 mgKOH / g, the hydroxyl value is 56 ± 4 mgKOH / g, the water content ≤ 0.02%, and the viscosity reaches 400-600 mPa·s / 75 °C, the bio-based silicon-based polyester polyol is obtained.

[0034] It is understandable that the protective gas mentioned above is a gas well-known in the art that is inert or inactive towards the reaction, raw materials and products, etc., such as at least one of rare gases (such as helium, argon, etc.) or nitrogen, and will not be specifically elaborated here.

[0035] <Bio-based chain extender>

[0036] In the present application, the bio-based chain extender refers to a bio-based diol having 2 to 4 carbon atoms, which is an organic compound containing two hydroxyl groups (—OH) in its molecular structure and obtained through such routes as biological fermentation, modification of natural oils, or conversion of sugars. Specific examples include but are not limited to at least one of bio-based 1,3-propanediol (PDO), bio-based 1,4-butanediol (BDO), and bio-based ethylene glycol. In some examples, the bio-based chain extender is 1,3-propanediol (PDO).

[0037] <Diisocyanate>

[0038] 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 polyurethanes. 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).

[0039] 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 well-known polyurethane preparation processes in the art, and the specific process conditions and parameters can be adjusted or optimized as needed.

[0040] In some examples, the method for preparing the bio-based polyurethane includes the following steps:

[0041] Mix and disperse the bio-based silicon-based polyester polyol and the bio-based chain extender evenly at 30 to 50 °C, add the diisocyanate and the catalyst, react at 60 to 80 °C for 6 to 10 hours, dilute and adjust the viscosity to a solid content of 25 ± 1% and a viscosity of 30 to 60 Pa·s / 25 °C to obtain the bio-based polyurethane.

[0042] Among them, the catalyst is a commonly used component in the preparation of polyurethanes in the art and is not particularly limited. Common examples include amine catalysts, metal catalysts (such as tin-based and bismuth-based), or environmentally friendly catalysts. In some specific examples, the catalyst used is MB20. There is no special requirement for the dosage of the catalyst, and it can be added according to the conventional dosage.

[0043] In the present application, dilution and viscosity adjustment are carried out using solvents well-known in the art. Specific examples include dimethylformamide, etc., but are not limited thereto.

[0044] 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 can be understood that other functional additives or components for optimizing its performance can also be added to the polyurethane film as needed to endow it with corresponding properties, and there is no special limitation here.

[0045] The following are specific examples of the present application. It should be noted that the following specific examples are only for illustrative purposes and do not limit the scope of the present application in any way.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used in the specification of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0047] In addition, unless otherwise specified, the methods without specific conditions or steps recorded are conventional methods, and the reagents and materials used can be obtained from commercial channels.

[0048] The specific information of the main raw materials used in the following examples and comparative examples is as follows:

[0049] Bio-based 1,3-propanediol (PDO), DuPont Biotechnology Co., Ltd.

[0050] Bio-based succinic acid, Shandong Landian Biotechnology Co., Ltd.

[0051] Mono-terminal dihydroxy siloxane SL-472X, Hangzhou Chongyao Technology Development Co., Ltd., and its molecular weight can be customized as needed.

[0052] Antioxidant UHS-8080LF, Yuanhe Industry Co., Ltd.

[0053] Example 1

[0054] In this example, a preparation method of bio-based silicon-based polyester polyol is provided, and the specific steps are as follows:

[0055] Add the mono-terminal dihydroxy siloxane, bio-based dibasic acid, and antioxidant UHS-8080LF into the reaction kettle, stir and mix them evenly, and then introduce nitrogen; control the temperature at the top of the rectifying column not to exceed 100 °C, gradually heat up to 205 °C, after detecting that the acid value drops to 10 mgKOH / g, add the catalyst TPT, continue the reaction, and start the first vacuum pumping; when the acid value is less than 1.0 mgKOH / g, set the temperature of the reaction kettle to 225 °C and start the second vacuum pumping; after the transesterification reaction for 7 h, remove the water and small molecular silicone oil in the system to obtain the bio-based silicon-based polyester polyol, whose acid value is 0.29 mgKOH / g, hydroxyl value is 56.12 mgKOH / g, water content is 0.017%, and viscosity is 470 Pa·s / 75 °C. The raw material composition and dosage are shown in Table 1.

[0056] Example 2

[0057] A preparation method of a bio-based silicon-based polyester polyol is provided in this example, and the specific steps are as follows:

[0058] Add the mono-terminal dihydroxy siloxane, bio-based dibasic acid, and antioxidant UHS-8080LF into the reaction kettle, stir and mix them evenly, and then introduce nitrogen; control the temperature at the top of the rectifying column not to exceed 100 °C, gradually heat up to 205 °C, after detecting that the acid value drops to 10 mgKOH / g, add the catalyst TPT, continue the reaction, and start the first vacuum pumping; when the acid value is less than 1.0 mgKOH / g, set the temperature of the reaction kettle to 225 °C and start the second vacuum pumping; after the transesterification reaction for 7 h, remove the water and small molecular silicone oil in the system to obtain the bio-based silicon-based polyester polyol, whose acid value is 0.23 mgKOH / g, hydroxyl value is 56.32 mgKOH / g, water content is 0.019%, and viscosity is 480 Pa·s / 75 °C. The raw material composition and dosage are shown in Table 1.

[0059] Example 3

[0060] A preparation method of a bio-based silicon-based polyester polyol is provided in this example, and the specific steps are as follows:

[0061] Add single-end dihydroxy siloxane, bio-based dibasic acid, and antioxidant UHS-8080LF into a reaction kettle. After stirring and mixing evenly, introduce nitrogen gas. Control the temperature at the top of the rectifying column not to exceed 100 °C. After gradually increasing the temperature to 205 °C, when the acid value is detected to have decreased to 10 mgKOH / g, add catalyst TPT and continue the reaction. Start the first vacuum pumping. When the acid value is less than 1.0 mgKOH / g, set the temperature of the reaction kettle to 225 °C and start the second vacuum pumping. After 7 hours of transesterification reaction, remove the water and small molecule silicone oil in the system to obtain bio-based silicon-based polyester polyol with an acid value of 0.25 mgKOH / g, a hydroxyl value of 55.96 mgKOH / g, a moisture content of 0.016%, and a viscosity of 470 Pa·s / 75 °C. The raw material composition and dosage are shown in Table 1.

[0062] Table 1 Raw material composition and dosage of bio-based silicon-based polyester polyol in Examples 1-3

[0063]

[0064] Example 4

[0065] In this example, a preparation method of bio-based polyurethane is provided, and the specific steps are as follows:

[0066] Mix and disperse the bio-based silicon-based polyester polyol (100 g) prepared in Example 1 and bio-based chain extender 1,3-propanediol (7.6 g) evenly at 35 °C. Add diisocyanate MDI (37.5 g) and catalyst MB20 (57 ppm), and react at 65 °C for 8 hours. Dilute and adjust the viscosity with solvent dimethylformamide to obtain bio-based polyurethane with a solid content of 25% and a viscosity of 49 Pa·s / 25 °C.

[0067] Example 5

[0068] In this example, a preparation method of bio-based polyurethane is provided, and the specific steps are as follows:

[0069] Mix and disperse the bio-based silicon-based polyester polyol (100 g) prepared in Example 1 and bio-based chain extender 1,3-propanediol (15.2 g) evenly at 35 °C. Add diisocyanate MDI (62.5 g) and catalyst MB20 (70 ppm), and react at 65 °C for 8 hours. Dilute and adjust the viscosity with solvent dimethylformamide to obtain bio-based polyurethane with a solid content of 25% and a viscosity of 53 Pa·s / 25 °C.

[0070] Example 6

[0071] In this example, a preparation method of bio-based polyurethane is provided, and the specific steps are as follows:

[0072] The bio-based silicon-based polyester polyol (100 g) prepared in Example 2 and the bio-based chain extender 1,3-propanediol (7.6 g) were mixed and dispersed evenly at 35 °C. Then, diisocyanate MDI (37.5 g) and catalyst MB20 (57 ppm) were added, and the reaction was carried out at 65 °C for 8 hours. The viscosity was adjusted by diluting with the solvent dimethylformamide to obtain a bio-based polyurethane with a solid content of 25% and a viscosity of 52 Pa·s / 25 °C.

[0073] Example 7

[0074] In this example, a preparation method of a bio-based polyurethane is provided, and the specific steps are as follows:

[0075] The bio-based silicon-based polyester polyol (100 g) prepared in Example 2 and the bio-based chain extender 1,3-propanediol (15.2 g) were mixed and dispersed evenly at 35 °C. Then, diisocyanate MDI (62.5 g) and catalyst MB20 (70 ppm) were added, and the reaction was carried out at 65 °C for 8 hours. The viscosity was adjusted by diluting with the solvent dimethylformamide to obtain a bio-based polyurethane with a solid content of 25% and a viscosity of 49 Pa·s / 25 °C.

[0076] Example 8

[0077] In this example, a preparation method of a bio-based polyurethane is provided, and the specific steps are as follows:

[0078] The bio-based silicon-based polyester polyol (100 g) prepared in Example 3 and the bio-based chain extender 1,3-propanediol (7.6 g) were mixed and dispersed evenly at 35 °C. Then, diisocyanate MDI (37.5 g) and catalyst MB20 (57 ppm) were added, and the reaction was carried out at 65 °C for 8 hours. The viscosity was adjusted by diluting with the solvent dimethylformamide to obtain a bio-based polyurethane with a solid content of 25% and a viscosity of 56 Pa·s / 25 °C.

[0079] Example 9

[0080] In this example, a preparation method of a bio-based polyurethane is provided, and the specific steps are as follows:

[0081] The bio-based silicon-based polyester polyol (100 g) prepared in Example 3 and the bio-based chain extender 1,3-propanediol (15.2 g) were mixed and dispersed evenly at 35 °C. Then, diisocyanate MDI (62.5 g) and catalyst MB20 (70 ppm) were added, and the reaction was carried out at 65 °C for 8 hours. The viscosity was adjusted by diluting with the solvent dimethylformamide to obtain a bio-based polyurethane with a solid content of 25% and a viscosity of 48 Pa·s / 25 °C.

[0082] Table 2 Raw material components and dosages of bio-based polyurethanes in Examples 4-9

[0083]

[0084] Comparative Example 1

[0085] Another preparation method of bio-based polyurethane is disclosed in this comparative example. The same implementation manner as in Example 4 is adopted, and the only difference is that the bio-based silicon-based polyester polyol is replaced with bis-terminal mono-hydroxy silicone oil with a molecular weight of 2000 in equal mass. The compositions of other raw materials and process conditions are the same as those in Example 4.

[0086] Comparative Example 2

[0087] Another preparation method of bio-based polyurethane is disclosed in this comparative example. The same implementation manner as in Example 4 is adopted, and the only difference is that the bio-based silicon-based polyester polyol is replaced with mono-terminal di-hydroxy silicone oil with a molecular weight of 2000 in equal mass. The compositions of other raw materials and process conditions are the same as those in Example 4.

[0088] Comparative Example 3

[0089] Another preparation method of bio-based polyurethane is disclosed in this comparative example. The specific steps are as follows:

[0090] First, mono-terminal di-hydroxy siloxane (50 g with a molecular weight of 2000) and isocyanate MDI (10 g) are mixed and dispersed evenly at 35°C, and reacted at 65°C for 1 h to obtain an organosilicon polyurethane prepolymer. Then, bio-based chain extender 1,3-propanediol (7.6 g) and bio-based polyester polyol (50 g with a molecular weight of 2000) are added and dispersed evenly. Finally, diisocyanate MDI (27.5 g) and catalyst MB20 (57 ppm) are added, and the reaction is carried out at 65°C for 8 hours. The bio-based polyurethane is prepared by diluting and adjusting the viscosity with solvent dimethylformamide, and its solid content is 25% and the viscosity is 47 Pa·s / 25°C.

[0091] Performance Test

[0092] 1. The bio-based polyurethanes in Examples 4 - 9 and Comparative Examples 1 - 3 are made into polyurethane films, that is, the bio-based polyurethanes in Examples 4 - 9 and Comparative Examples 1 - 3 are scraped on a glass plate and treated in an oven at 130°C for 3 hours to prepare a dry film with a thickness of 0.1 mm. After cooling and standing at room temperature for 72 hours, the mechanical properties, anti-fouling and water-repellent properties are tested. The test results are shown in Table 3.

[0093] Table 3 Test Results of Mechanical Properties, Anti-fouling and Water-repellent Properties of Polyurethane Films

[0094]

[0095] Among them, each test item is carried out according to the following method:

[0096] (1)The tensile property test was carried out according to the methods of GB / T 1040.1-2018 and GB / T 1040.3-2006.

[0097] (2)The water contact angle was measured according to the standard of GB / T 30693-2014.

[0098] (3)Anti-fouling performance test: A 30-mm square pollution spot was smeared on a square specimen with a side length of 200 mm, placed at room temperature for 24 h, wiped vigorously with a paper napkin (60 back-and-forth movements within 2 min), and the evaluation grade was carried out according to GB / T 251-2008. The polluting agents were tomato ketchup, gasoline engine oil, freshly squeezed orange juice, instant coffee, tea, and red wine.

[0099] As can be seen from Table 3, in Examples 4-9, polyols were prepared by the esterification reaction of mono-terminal dihydroxy siloxane and bio-based succinic acid. At the same time, the hydroxyl groups with reactive activity were located at both ends of the main chain, and the water-repellent and anti-fouling silicone oxygen chains were suspended on the side chains. Moreover, it was liquid at room temperature and had obvious compatibility advantages. When it was used as a polyol to prepare bio-based polyurethane, the mechanical properties were improved, and the bio-based silicon-based polyester polyol was introduced into the polyurethane to form a surface brush-like anti-fouling structure, with the water contact angle above 113°, and the anti-fouling and water-repellent effects were excellent. Generally speaking, the bio-based polyurethane in this application has excellent anti-fouling and water-repellent properties, high mechanical properties, and good comprehensive performance. In Comparative Examples 1, 2, and 3, due to the unmodified hydroxy siloxane directly reacting with isocyanate, there were obvious phase separation problems.

[0100] 2. The bio-based polyurethanes in Examples 4-9 and Comparative Examples 1-3 were formulated into slurries according to the following method:

[0101] 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, and stir in a blender for 5 minutes to disperse evenly to obtain a slurry.

[0102] By allowing the above-prepared slurry to stand at room temperature for the same time to observe the uniformity of the pigment at different time points, as well as whether there is flocculation, floating, stratification, etc. The results are shown in Table 4.

[0103] Table 4 Test results of the stability of polyurethane slurries

[0104]

[0105] As can be seen from Table 4, when a polyol is prepared by the esterification reaction of a mono-terminal dihydroxy siloxane and a bio-based succinic acid and used as a polyol for preparing a bio-based polyurethane, compared with the direct reaction of a two-terminal mono-hydroxy silicone oil or a mono-terminal dihydroxy silicone oil as a polyol and an isocyanate in Comparative Examples 1, 2 and 3, the compatibility of the siloxane and the polyurethane can be improved, good pigment dispersion stability can be imparted to the polyurethane slurry, which is of great significance to the color stability of the silicone-based polyurethane in the subsequent processing.

[0106] It should be noted that when the experimental process meets the following conditions, the purpose of this application can be achieved:

[0107] For the bio-based dicarboxylic acid, it can also be bio-based sebacic acid.

[0108] For the temperature of preparing the bio-based silicon-based diol, it can be 220 - 240 °C, specifically any temperature among 220 °C, 225 °C, 230 °C, 235 °C, 240 °C, etc. or the temperature between any two temperature ranges.

[0109] For the bio-based chain extender, it can also be bio-based 1,4-butanediol or ethylene glycol.

[0110] For the reaction conditions of the bio-based polyurethane, among them, the bio-based silicon-based polyester polyol and the bio-based chain extender are preferably mixed and dispersed evenly at 30 - 50 °C, and it can also be any temperature among 30 °C, 35 °C, 40 °C, 45 °C or 50 °C or the temperature between any two temperature ranges; after adding the diisocyanate and the catalyst, it is preferably reacted at 60 - 80 °C for 6 - 10 hours, the temperature can be any temperature among 60 °C, 65 °C, 70 °C, 75 °C or 80 °C or the temperature between any two temperature ranges, and the time can be adjusted as needed, such as 6 h, 7 h, 8 h, 9 h or 10 h, etc.

[0111] For the above process parameters, those skilled in the art can make appropriate selections according to actual needs, and all of them can achieve the purpose of this application.

[0112] It should be noted that this application is not limited to the above embodiments. The above embodiments are only examples, and the embodiments with the same composition and the same effect as the technical idea within the technical solution scope of this application are all included in the technical scope of this application. In addition, within the scope not departing from the gist of this application, various deformations that those skilled in the art can think of are imposed on the embodiments, and other ways constructed by combining some constituent elements in the embodiments are also included in the scope of this application.

Claims

1. A bio-based polyurethane, characterized in that, It is prepared from a bio-based silicon-based polyester polyol, a diisocyanate, and a bio-based chain extender with a molar ratio of 1.0:(3.0 - 5.0):(2.0 - 4.0); Among them, the bio-based silicon-based polyester polyol is prepared by an esterification reaction using a bio-based dibasic acid and a mono-terminal dihydroxy siloxane. The weight percentages of the components required for preparing the bio-based silicon-based polyester polyol are respectively: mono-terminal dihydroxy siloxane 75 - 95%, bio-based dibasic acid 5 - 25%, antioxidant 0 - 0.05%, catalyst 0 - 0.02%; The structural general formula of the mono-terminal dihydroxy siloxane is as follows: ； Among them, n is an integer from 1 to 10, and R' is an alkyl group.

2. The bio-based polyurethane according to claim 1, wherein 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-propanediol, bio-based 1,4-butanediol, and bio-based ethylene glycol.

4. The bio-based polyurethane according to claim 1, wherein 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 number-average molecular weight of the mono-terminal dihydroxy siloxane is 290 - 1000.

6. The bio-based polyurethane according to claim 1, characterized in that, The preparation method of the bio-based silicon-based polyester polyol includes the following steps: S1. Take the mono-terminal dihydroxy siloxane, bio-based dibasic acid, and antioxidant, stir and mix them evenly, and then introduce a protective gas; S2. Control the temperature at the top of the rectifying column not to exceed 100°C, gradually heat up to 205°C, after detecting that the acid value has decreased to 10 mgKOH / g, add the catalyst, continue the reaction, and start the first vacuum pumping; S3. When the acid value is less than 1.0 mgKOH / g, set the temperature of the reaction kettle at 220 - 240°C, and start the second vacuum pumping; S4. After an ester exchange reaction for 5 - 10 h, remove the water and mono-terminal dihydroxy siloxane in the system. When the acid value ≤ 0.3 mgKOH / g, the hydroxyl value is 56 ± 4 mgKOH / g, the water content ≤ 0.02%, and the viscosity reaches 400 - 600 mPa·s / 75°C, a bio-based silicon-based polyester polyol is obtained.

7. A method for preparing a bio-based polyurethane according to any one of claims 1-6, characterized in that, It includes the following steps: Mix and disperse the bio-based silicon-based polyester polyol and the bio-based chain extender evenly at 30 - 50°C, add the diisocyanate and the catalyst, react at 60 - 80°C for 6 - 10 hours, dilute and adjust the viscosity to a solid content of 25 ± 1% and a viscosity of 30 - 60 Pa·s / 25°C to prepare a bio-based polyurethane.

8. A polyurethane film, characterized in that, Containing the bio-based polyurethane according to any one of claims 1 - 6.

Images