Preparation method of bio-based cross-linked polyurethane

Abstract

The invention relates to a preparation method of bio-based cross-linked polyurethane. The preparation method comprises the following steps: firstly, modifying a double bond of a side chain of urushiol to prepare epoxy urushiol, further mixing the epoxy urushiol with polyol and graphene oxide, reacting with polyisocyanate, and after casting molding, crosslinking epoxy groups on the side chain of the epoxy urushiol and the graphene oxide to obtain the casting polyurethane with an interpenetrating network. According to the invention, by utilizing the plasticizing performance of a benzene ring and a long side chain in the urushiol structure, the interaction force between prepolymer molecules is weakened, the viscosity of the prepolymer is reduced, the fluidity of the prepolymer is improved, and the uniformity of the casting polyurethane is further improved; meanwhile, modified epoxy groups of unsaturated long carbon chains in urushiol can be cross-linked with the graphene oxide under the action of a catalyst, so that an IPN interpenetrating network structure is quickly formed in a polyurethane matrix, and the mechanical property of the pouring type polyurethane is improved.

Description

Technical Field

[0001] The invention relates to the technical field of polyurethane elastomer preparation, in particular to a method for preparing bio-based cross-linked polyurethane. Background Art

[0002] Casting polyurethane (CPU) for shoes has become an ideal outsole material in the manufacture of high-end leather shoes and sports shoes due to its advantages of high wear resistance, high anti-slip, high toughness, comfortable and soft wearing, and good processability. At present, CPU for shoes mainly adopts the prepolymer method or semi-prepolymer process, involving a two-component or three-component system. Component A is usually composed of polyols and chain extenders; component B is a terminal isocyanate prepolymer generated by the reaction of polyols and isocyanates; component C is a catalyst, which is often mixed with component A. In the CPU casting process, components A and B are rapidly mixed in a very short time (usually a few seconds) in liquid form and induce a violent chemical reaction. In this process, accurate metering and uniform mixing are crucial to ensure the quality of the final product. However, the existing process has some limitations. In order to improve the comprehensive performance of elastomers, prepolymers often have higher viscosity and poor fluidity, which may cause uneven mixing of components A and B in the automated rapid blending casting process, affecting the stability of product quality.

[0003] In view of this, the inventor conducted in-depth research on the above-mentioned issues, and thus the present case was produced. Summary of the invention

[0004] In order to effectively solve the above problems, the present invention provides a method for preparing a bio-based cross-linked polyurethane, firstly, the double bonds of the urushiol side chain are epoxidized to obtain epoxy urushiol. Then, the epoxy urushiol is reacted with polyol, graphene oxide, and isocyanate, and after casting, the epoxy groups on the urushiol side chain are cross-linked with graphene oxide to obtain a cast polyurethane with an interpenetrating network.

[0005] The present invention adopts the following technical solution:

[0006] A method for preparing a bio-based cross-linked polyurethane comprises the following steps:

[0007] 1) mixing the polyol, epoxy urushiol, graphene oxide and a catalyst to obtain a mixture A;

[0008] 2) Mixing mixture A and polyisocyanate uniformly, reacting at 60-85° C. for 15-30 minutes, and controlling the viscosity to be 2000-5000 cps, to obtain prepolymer B;

[0009] 3) The prepolymer B and the chain extender are mixed evenly and injected into a mold, and molded at 60-110° C. for 15-60 minutes; the product is then placed in an environment of 33-37° C. and 45-55% for aging for 12-24 hours to obtain the above-mentioned bio-based cross-linked polyurethane.

[0010] Furthermore, the mass ratio of the above-mentioned polyol, epoxy lacquer phenol, graphene oxide, polyisocyanate, chain extender and catalyst is 85-95:5-15:1-5:25-50:20-40:0.1-0.5.

[0011] Furthermore, the epoxy lacquer phenol is prepared according to the following method:

[0012] (i) Urushiol, xylene, acetic anhydride and pyridine are mixed evenly in a mass ratio of 100:50:30:75, heated at 90°C, and reacted for 1.5 hours. After the reaction is completed, the mixture is washed with water until neutral, the oil layer is separated, and the pyridine is removed by evaporation under reduced pressure to obtain acetylated urushiol;

[0013] (ii) Add urushiol and formic acid in a mass ratio of 1:1 to 3 into a three-necked flask, use magnetic stirring, heat to 60°C, and then add hydrogen peroxide dropwise. Keep the temperature constant for 6 to 12 hours, then cool to room temperature, wash with deionized water until neutral, and distill under reduced pressure to obtain the above-mentioned epoxy urushiol.

[0014] (iii) The product obtained in (ii) was dissolved in ethanol, and sodium hydroxide was added in an amount of 5% by weight of the total solution, and the mixture was reacted at 45° C. for 0.5 h. After the reaction was completed, dilute hydrochloric acid was added to adjust the pH to 7, and the mixture was filtered, and the solvent was removed by evaporation under reduced pressure, and the mixture was dried in vacuo to obtain the product epoxy urushiol.

[0015] Furthermore, the mass percentage concentration of the above hydrogen peroxide is 30-70%, and the total added amount is 150%-300% of the mass of urushiol.

[0016] Furthermore, the above-mentioned polyol is polyester diol and / or polyether diol.

[0017] Furthermore, the polyisocyanate is an aliphatic diisocyanate and / or an aromatic diisocyanate.

[0018] Furthermore, the catalyst is an organic tin and / or titanate compound.

[0019] Furthermore, the chain extender is a small molecule diol and / or a diamine.

[0020] It can be seen from the above description of the present invention that, compared with the prior art, the present invention has the following advantages:

[0021] 1. Cardanol is the main component of raw lacquer, with the characteristics of wide sources, renewability, low toxicity and biodegradability. Urushiol is a catechol with unsaturated long side carbon chains. Its molecules have both polar groups and non-polar groups, and are natural amphiphilic compounds. As a derivative of catechol, the special chemical structure of the phenolic hydroxyl group and the unsaturated C=C on the long side chain of urushiol and the resulting physical and chemical properties also provide many other advantages of improvement and modification. Polyoxyethylene ether or polyoxypropylene ether prepared by the addition reaction of phenolic hydroxyl groups of urushiol with ethylene oxide or propylene oxide has been well applied in the synthesis of polymer materials such as thermosetting epoxy resins and phenolic resins as a new generation of safe, mild and green environmentally friendly surfactants. The benzene ring and long side chain in its structure have good plasticizing properties, which can increase the distance between prepolymer polyol molecules, weaken the interaction between molecules, reduce the viscosity of the prepolymer, increase the fluidity of the prepolymer, and improve the uniformity of cast polyurethane.

[0022] 2. The present application performs epoxidation modification on the double bonds of the urushiol side chain to obtain epoxy urushiol, and then further reacts the epoxy urushiol with polyols, graphene oxide, and isocyanate. After casting and molding, the epoxy groups on the urushiol side chains are cross-linked with graphene oxide to obtain a cast polyurethane with an interpenetrating network, which is beneficial to improving the mechanical properties of the modified CPU, and producing an environmentally friendly shoe CPU product with low manufacturing difficulty, stable quality, storage resistance, fast cross-linking, and excellent performance.

[0023] 3. The present application utilizes the plasticizing properties of the benzene ring and long side chains in the lacquer phenol structure to weaken the interaction between prepolymer molecules, reduce the viscosity of the prepolymer, increase the fluidity of the prepolymer, and thereby improve the uniformity of the cast polyurethane.

[0024] 4. The unsaturated long carbon chain in the epoxy lacquer phenol of the present application can be polymerized with the modified epoxy group and graphene oxide under the action of a small molecule chain extender, thereby quickly forming an IPN interpenetrating network structure in the polyurethane matrix, thereby improving the mechanical properties of the cast polyurethane. DETAILED DESCRIPTION

[0025] The following examples can help those skilled in the art to better understand the present invention, but they are not intended to limit the present invention in any form.

[0026] Example 1

[0027] 1. The preparation method of epoxy lacquer phenol is as follows:

[0028] (i) Urushiol, xylene, acetic anhydride and pyridine are mixed evenly in a mass ratio of 100:50:30:75, heated at 90°C, and reacted for 1.5 hours. After the reaction is completed, the mixture is washed with water until neutral, the oil layer is separated, and the pyridine is removed by evaporation under reduced pressure to obtain acetylated urushiol;

[0029] (ii) Add urushiol and formic acid in a mass ratio of 1:2.2 into a three-necked flask, use magnetic stirring, heat to 60° C., and begin to dropwise add 50% hydrogen peroxide, with the total added amount being 200% of the mass of urushiol. Keep the reaction at a constant temperature for 8 hours, then cool to room temperature, wash with deionized water until neutral, and distill under reduced pressure to obtain the epoxy urushiol.

[0030] (iii) The product obtained in (ii) was dissolved in ethanol, and sodium hydroxide was added in an amount of 5% by weight of the total solution, and the mixture was reacted at 45° C. for 0.5 h. After the reaction was completed, dilute hydrochloric acid was added to adjust the pH to 7, and the mixture was filtered, and the solvent was removed by evaporation under reduced pressure, and the mixture was dried in vacuo to obtain the product epoxy urushiol.

[0031] 2. The preparation method of bio-based cross-linked polyurethane is as follows:

[0032] (1) mixing polybutylene adipate, epoxy lacquer phenol, graphene oxide, and stannous octoate in a formula ratio to obtain a mixture A;

[0033] (2) Mixing mixture A and TDI uniformly, reacting at 65° C. for 25 min, and controlling the viscosity to be 4000 cps, to obtain prepolymer B;

[0034] (3) Prepolymer B and butanediol are mixed evenly and injected into a mold, and molded at 90° C. for 20 minutes; the product is then placed in an environment at 37° C. and 50% humidity for aging for 24 hours to obtain a cardanol-based cross-linked polyurethane.

[0035] The mass ratio of polybutylene adipate, TDI, epoxy lacquer phenol, graphene oxide, butanediol and stannous octoate is 95:40:5:1:40:0.1.

[0036] Example 2

[0037] 1. The preparation method of epoxy lacquer phenol is as follows:

[0038] (i) Urushiol, xylene, acetic anhydride and pyridine are mixed evenly in a mass ratio of 100:50:30:75, heated at 90°C, and reacted for 1.5 hours. After the reaction is completed, the mixture is washed with water until neutral, the oil layer is separated, and the pyridine is removed by evaporation under reduced pressure to obtain acetylated urushiol;

[0039] (ii) Add urushiol and formic acid in a mass ratio of 1:2.2 into a three-necked flask, use magnetic stirring, heat to 60° C., and begin to dropwise add 50% hydrogen peroxide, with the total added amount being 200% of the mass of urushiol. Keep the reaction at a constant temperature for 8 hours, then cool to room temperature, wash with deionized water until neutral, and distill under reduced pressure to obtain the epoxy urushiol.

[0040] (iii) The product obtained in (ii) was dissolved in ethanol, and sodium hydroxide was added in an amount of 5% by weight of the total solution, and the mixture was reacted at 45° C. for 0.5 h. After the reaction was completed, dilute hydrochloric acid was added to adjust the pH to 7, and the mixture was filtered, and the solvent was removed by evaporation under reduced pressure, and the mixture was dried in vacuo to obtain the product epoxy urushiol.

[0041] 2. The preparation method of bio-based cross-linked polyurethane is as follows:

[0042] (1) mixing polybutylene adipate, epoxy lacquer phenol, graphene oxide, and stannous octoate in a formula ratio to obtain a mixture A;

[0043] (2) Mixing mixture A and TDI uniformly, reacting at 65° C. for 25 min, and controlling the viscosity to be 4000 cps, to obtain prepolymer B;

[0044] (3) Prepolymer B and butanediol are mixed evenly and injected into a mold, and molded at 90° C. for 20 minutes; the product is then placed in an environment at 37° C. and 50% humidity for aging for 24 hours to obtain a cardanol-based cross-linked polyurethane.

[0045] The mass ratio of polybutylene adipate, TDI, epoxy lacquer phenol, graphene oxide, butanediol and stannous octoate is 90:40:10:2:40:0.1.

[0046] Example 3

[0047] 1. The preparation method of epoxy lacquer phenol is as follows:

[0048] (i) Urushiol, xylene, acetic anhydride and pyridine are mixed evenly in a mass ratio of 100:50:30:75, heated at 90°C, and reacted for 1.5 hours. After the reaction is completed, the mixture is washed with water until neutral, the oil layer is separated, and the pyridine is removed by evaporation under reduced pressure to obtain acetylated urushiol;

[0049] (ii) Add urushiol and formic acid in a mass ratio of 1:2.2 into a three-necked flask, use magnetic stirring, heat to 60° C., and begin to dropwise add 50% hydrogen peroxide, with the total added amount being 200% of the mass of urushiol. Keep the reaction at a constant temperature for 8 hours, then cool to room temperature, wash with deionized water until neutral, and distill under reduced pressure to obtain the epoxy urushiol.

[0050] (iii) The product obtained in (ii) was dissolved in ethanol, and sodium hydroxide was added in an amount of 5% by weight of the total solution, and the mixture was reacted at 45° C. for 0.5 h. After the reaction was completed, dilute hydrochloric acid was added to adjust the pH to 7, and the mixture was filtered, and the solvent was removed by evaporation under reduced pressure, and the mixture was dried in vacuo to obtain the product epoxy urushiol.

[0051] 2. The preparation method of bio-based cross-linked polyurethane is as follows:

[0052] (1) mixing polybutylene adipate, epoxy lacquer phenol, graphene oxide, and stannous octoate in a formula ratio to obtain a mixture A;

[0053] (2) Mixing mixture A and TDI uniformly, reacting at 65° C. for 25 min, and controlling the viscosity to be 4000 cps, to obtain prepolymer B;

[0054] (3) Prepolymer B and butanediol are mixed evenly and injected into a mold, and molded at 90° C. for 20 minutes; the product is then placed in an environment at 37° C. and 50% humidity for aging for 24 hours to obtain a cardanol-based cross-linked polyurethane.

[0055] The mass ratio of polybutylene adipate, TDI, epoxy lacquer phenol, graphene oxide, butanediol and stannous octoate is 85:40:10:3:40:0.1.

[0056] Comparative Example 1:

[0057] (1) polybutylene adipate and stannous octoate are uniformly stirred according to a formula ratio to obtain a mixture A, and the mixture is stored in an oven at 75° C.;

[0058] (2) Butanediol and TDI are mixed evenly, reacted at 75°C for 15 to 30 minutes to obtain prepolymer B, and stored in an oven at 75°C;

[0059] (3) Mixing mixture A and prepolymer B uniformly, injecting into a mold, and molding at 75° C. for 20 minutes; then placing the product in an environment of 37° C. and 50% humidity for aging for 24 hours to obtain a cast polyurethane.

[0060] The mass ratio of polybutylene adipate, TDI, butanediol and stannous octoate is 100:40:40:0.1.

[0061] Table 1 CPU performance test

[0062]

[0063] It can be seen from Examples 1 to 3 in the table that with the increase in the amount of epoxy lacquer phenol and graphene oxide, the Shore A hardness, tensile strength, and right-angle tear of the CPU gradually increase, and the elongation at break decreases. Compared with Comparative Example 1, the mechanical strength is significantly improved, indicating that the polyurethane / lacquer phenol / graphene oxide IPN interpenetrating network structure formed by cross-linking epoxy lacquer phenol and graphene oxide in the embodiments is beneficial to improving the rigidity of the CPU, but with the increase in the degree of crosslinking, its flexibility will be affected to a certain extent. In general, the comprehensive performance of the CPU modified by cardanol polyether is better than that of the ordinary CPU.

[0064] The above is only a specific implementation of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial changes to the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. A method for preparing a bio-based cross-linked polyurethane, characterized in that: The following steps are involved: 1) mixing the polyol, epoxy urushiol, graphene oxide and a catalyst to obtain a mixture A; 2) Mixing mixture A and polyisocyanate uniformly, reacting at 60-85° C. for 15-30 minutes, and controlling the viscosity to be 2000-5000 cps, to obtain prepolymer B; 3) The prepolymer B and the chain extender are mixed evenly and injected into a mold, and molded at 60-110° C. for 15-60 minutes; the product is then placed in an environment at 33-37° C. and 45-55% for aging for 12-24 hours to obtain the bio-based cross-linked polyurethane.

2. The method for preparing a bio-based cross-linked polyurethane according to claim 1, characterized in that: The mass ratio of the polyol, epoxy lacquer phenol, graphene oxide, polyisocyanate, chain extender and catalyst is 85-95:5-15:1-5:25-50:20-40:0.1-0.

5.

3. The method for preparing a bio-based cross-linked polyurethane according to claim 1, characterized in that: The epoxy lacquer phenol is prepared according to the following method: (i) Urushiol, xylene, acetic anhydride and pyridine are mixed evenly in a mass ratio of 100:50:30:75, heated at 90°C, and reacted for 1.5 hours. After the reaction is completed, the mixture is washed with water until neutral, the oil layer is separated, and the pyridine is removed by evaporation under reduced pressure to obtain acetylated urushiol; (ii) Add urushiol and formic acid in a mass ratio of 1:1 to 3 into a three-necked flask, use magnetic stirring, heat to 60° C., start to dropwise add hydrogen peroxide, react at a constant temperature for 6 to 12 hours, then cool to room temperature, wash with deionized water until neutral, and distill under reduced pressure to obtain the epoxy urushiol. (iii) The product obtained in (ii) was dissolved in ethanol, and sodium hydroxide was added in an amount of 5% by weight of the total solution, and the mixture was reacted at 45° C. for 0.5 h. After the reaction was completed, dilute hydrochloric acid was added to adjust the pH to 7, and the mixture was filtered, and the solvent was removed by evaporation under reduced pressure, and the mixture was dried in vacuo to obtain the product epoxy urushiol.

4. The method for preparing a bio-based cross-linked polyurethane according to claim 1, characterized in that: The mass percentage concentration of the hydrogen peroxide is 30-70%, and the total added amount is 150-300% of the mass of urushiol.

5. The method for preparing a bio-based cross-linked polyurethane according to claim 1, characterized in that: The polyol is polyester diol and / or polyether diol.

6. The method for preparing a bio-based cross-linked polyurethane according to claim 1, characterized in that: The polyisocyanate is an aliphatic diisocyanate and / or an aromatic diisocyanate.

7. The method for preparing a bio-based cross-linked polyurethane according to claim 1, characterized in that: The catalyst is an organic tin and / or titanate compound.

8. The method for preparing a bio-based cross-linked polyurethane according to claim 1, characterized in that: The chain extender is a small molecule diol and / or a diamine.

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