Preparation method and application of functionalized carbon fiber in-situ polymerization modified polyurethane elastomer

Abstract

The invention relates to the technical field of new materials, and discloses a functionalized carbon fiber in-situ polymerization modified polyurethane elastomer, which takes ethanolamine phosphate modified carbon fiber as a growth site and hydroxyl of phosphate as a polymerization site, so that polycarbonate dihydric alcohol and 4, 4 '-dihydroxy-4, 4'-dihydroxy-4, 4 '-dihydroxy-4, 4'-dihydroxy-4, 4 '-dihydroxy-4, 4'-dihydroxy-4, 4 In-situ graft polymerization is carried out on 4, 4 '-diphenylmethane diisocyanate on the surface of the carbon fiber to obtain the functionalized carbon fiber in-situ polymerization modified polyurethane elastomer, three-dimensional chemical crosslinking sites are formed in the carbon fiber and the polyurethane elastomer, movement of a polyurethane molecular chain is hindered, the glass transition temperature and the thermal decomposition temperature of the polyurethane elastomer are increased, and the mechanical properties of the polyurethane elastomer are improved. And phosphate ester micromolecules modified on the surface of the carbon fiber are used as a phosphorus-containing flame retardant, can be decomposed to generate a phosphoric acid derivative during combustion, can capture combustion chain reaction free radicals and absorb water to promote carbonization, and the polyurethane elastomer has excellent flame retardance.

Description

Technical Field

[0001] The invention relates to the technical field of new materials, and in particular to a preparation method and application of a functionalized carbon fiber in-situ polymerization-modified polyurethane elastomer. Background Art

[0002] Carbon fiber (CNF) has the advantages of large specific surface area, high strength, good conductivity, and strong thermal stability. It is widely used in polymer materials, electrochemical energy devices, pollutant adsorption and other fields. Patent CN103214792B "A carbon fiber / epoxy resin composite material and its preparation method" discloses that carbon fiber and organic phosphorus flame retardants are used to modify epoxy resin, which has excellent flame retardancy and other comprehensive properties. Composite carbon fiber with polymer materials such as polyurethane and epoxy resin can improve the thermal stability, mechanical strength and other properties of the material.

[0003] Polyurethane elastomers can be made into shoes, clothing, medical devices, defense products and other products and are widely used. Polyurethane elastomers have excellent elasticity, good mechanical strength, and good chemical resistance, but their flame retardancy is poor and they are easy to burn. Therefore, improving the flame retardancy of polyurethane elastomers has important industrial significance. Combining carbon fiber and organophosphorus flame retardants and applying them to polyurethane elastomer materials can improve their comprehensive properties such as flame retardancy. Summary of the invention

[0004] 1. Technical issues to be resolved In view of the deficiencies in the prior art, the present invention provides a method for preparing and applying a functionalized carbon fiber in-situ polymerization-modified polyurethane elastomer, which significantly enhances the flame retardancy and thermal stability of the polyurethane elastomer.

[0005] (II) Technical solution To achieve the above object, the present invention provides the following technical solution: a functionalized carbon fiber in-situ polymerization-modified polyurethane elastomer, the preparation method comprising the following steps: (1) Prepare a mixed solution of concentrated sulfuric acid and concentrated nitric acid, add chopped carbon fibers, oxidize at 50-80 °C for 3-8 h, filter, wash with deionized water and dry to obtain oxidized carbon fibers.

[0006] (2) Add oxidized carbon fiber and toluene-2,4-diisocyanate to a toluene solvent, heat to 75-100 °C in a nitrogen atmosphere, react for 2-6 h, filter, wash with acetone and dry to obtain isocyanate-modified carbon fiber.

[0007] (3) Add isocyanate modified carbon fiber and diethanolamine phosphate compound (C 16 H 20NO5P) and a catalyst dibutyltin dilaurate are reacted at elevated temperature, filtered after the reaction, washed with ethanol and acetone and dried to obtain ethanolamine phosphate modified carbon fiber.

[0008] (4) The ethanolamine phosphate modified carbon fiber and polycarbonate diol are mixed evenly, and then 4,4'-diphenylmethane diisocyanate is added, and the catalyst dibutyltin dilaurate is added dropwise. The reaction is carried out at 65-75 °C in a nitrogen atmosphere for 2-3 h, and then the temperature is reduced to 40-50 °C, 1,4-butanediol is added, and the reaction is carried out for 20-40 min. The product is placed in an oven and aged at 100-120 °C for 6-12 h to obtain a functionalized carbon fiber in situ polymerization modified polyurethane elastomer.

[0009] Preferably, in the step (3), the isocyanate-modified carbon fiber is 100 parts, the diethanolamine phosphate compound is 15-60 parts, and the dibutyltin dilaurate is 0.5-2 parts by weight.

[0010] Preferably, the reaction in step (3) is carried out at 60-90° C. for 4-10 h.

[0011] Preferably, in the step (4), the weight ratio of ethanolamine phosphate modified carbon fiber is 0.5-3 parts, polycarbonate diol is 100 parts, 4,4'-diphenylmethane diisocyanate is 40-65 parts, dibutyltin dilaurate is 0.5-1.2 parts, and 1,4-butanediol is 3-8 parts.

[0012] Preferably, the functionalized carbon fiber in-situ polymerization-modified polyurethane elastomer is applied to flame-retardant polyurethane materials.

[0013] 3. Beneficial technical effects Compared with the prior art, the present invention has the following beneficial technical effects: The invention discloses a functionalized carbon fiber in-situ polymerized modified polyurethane elastomer. The hydroxyl and carboxyl functional groups on the surface of the carbon fiber are oxidized, and are modified with toluene-2,4-diisocyanate to introduce isocyanate functional groups on the surface of the carbon fiber. The isocyanate functional groups further react with a hydroxyl group of a diethanolamine phosphate compound under the catalytic action of dibutyltin dilaurate, thereby modifying the surface of the carbon fiber with ethanolamine phosphate small molecules to obtain functional ethanolamine phosphate modified carbon fiber.

[0014] With ethanolamine phosphate modified carbon fiber as the growth site and the hydroxyl group of phosphate as the polymerization site, polycarbonate diol and 4,4'-diphenylmethane diisocyanate are in situ grafted and polymerized on the surface of carbon fiber to obtain functionalized carbon fiber in situ polymerization modified polyurethane elastomer. Carbon fiber and polyurethane elastomer are grafted through chemical bonding, which enhances the interface bonding between the two and enables carbon fiber to better play the reinforcing modification effect. Three-dimensional chemical crosslinking sites are formed in carbon fiber and polyurethane elastomer, which hinders the movement of polyurethane molecular chains and increases the glass transition temperature and thermal decomposition temperature of polyurethane elastomer. In addition, carbon fiber has excellent thermal conductivity and is evenly dispersed in polyurethane, which has a good heat conduction effect and further improves the thermal stability of polyurethane elastomer. In addition, the phosphate small molecules modified on the surface of carbon fiber are used as phosphorus-containing flame retardants. When burned, they will decompose to generate phosphoric acid derivatives, which can capture the combustion chain reaction free radicals and inhibit the combustion reaction. At the same time, the phosphoric acid derivatives can absorb water to promote carbonization and form a continuous carbon barrier layer with carbon fiber to inhibit combustion and smoke, so that the polyurethane elastomer has excellent flame retardant properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is the reaction diagram of isocyanate modified carbon fiber and diethanolamine phosphate compound. DETAILED DESCRIPTION

[0016] To achieve the above object, the present invention provides the following embodiments and examples: A functionalized carbon fiber in-situ polymerization-modified polyurethane elastomer, the preparation method comprising the following steps: (1) Prepare a mixed solution of concentrated sulfuric acid and concentrated nitric acid, add chopped carbon fibers, oxidize at 50-80 °C for 3-8 h, filter, wash with deionized water and dry to obtain oxidized carbon fibers.

[0017] (2) Add oxidized carbon fiber and toluene-2,4-diisocyanate to a toluene solvent, heat to 75-100 °C in a nitrogen atmosphere, react for 2-6 h, filter, wash with acetone and dry to obtain isocyanate-modified carbon fiber.

[0018] (3) Add 100 parts by weight of isocyanate-modified carbon fiber and 15-60 parts by weight of diethanolamine phosphate compound (C 16 H 20 NO5P) and 0.5-2 parts of catalyst dibutyltin dilaurate (DBTDL), heating to 60-90 ° C, reacting for 4-10 hours, filtering after the reaction, washing with ethanol and acetone and drying to obtain ethanolamine phosphate modified carbon fiber.

[0019] (4) 0.5-3 parts by weight of ethanolamine phosphate modified carbon fiber and 100 parts of polycarbonate diol are mixed evenly, and then 40-65 parts of 4,4'-diphenylmethane diisocyanate are added, and 0.5-1.2 parts of catalyst dibutyltin dilaurate are added dropwise. The mixture is reacted at 65-75 °C in a nitrogen atmosphere for 2-3 h, and then the temperature is reduced to 40-50 °C. 3-8 parts of 1,4-butanediol are added and reacted for 20-40 min. The product is placed in an oven and aged at 100-120 °C for 6-12 h to obtain a functionalized carbon fiber in-situ polymerization modified polyurethane elastomer, which is used in flame-retardant polyurethane materials.

[0020] Example 1

[0021] (1) Prepare a mixed solution of 60 mL of concentrated sulfuric acid and 20 mL of concentrated nitric acid, add 0.5 g of chopped carbon fiber, oxidize at 50 °C for 3 h, filter, wash with deionized water and dry to obtain oxidized carbon fiber.

[0022] (2) Add 0.5 g of oxidized carbon fiber and 2 g of toluene-2,4-diisocyanate to 80 mL of toluene solvent, heat to 75 °C in a nitrogen atmosphere, react for 2 h, filter, wash with acetone and dry to obtain isocyanate-modified carbon fiber.

[0023] (3) Add 1 g of isocyanate-modified carbon fiber and 0.15 g of diethanolamine phosphate compound (C 16 H 20 NO5P) and 0.005 g of catalyst dibutyltin dilaurate, heated to 60 °C, reacted for 4 h, filtered after the reaction, washed with ethanol and acetone and dried to obtain ethanolamine phosphate modified carbon fiber.

[0024] (4) 0.5 g of ethanolamine phosphate modified carbon fiber and 5 g of polycarbonate diol were mixed evenly, and then 2 g of 4,4'-diphenylmethane diisocyanate was added, and 0.025 g of catalyst dibutyltin dilaurate was added dropwise. The mixture was reacted at 65 °C in a nitrogen atmosphere for 2 h. Then the temperature was lowered to 40 °C, 0.14 g of 1,4-butanediol was added, and the reaction was carried out for 20 min. The product was placed in an oven and aged at 100 °C for 6 h to obtain a functionalized carbon fiber in situ polymerization modified polyurethane elastomer.

[0025] Example 2

[0026] (1) Prepare a mixed solution of 80 mL of concentrated sulfuric acid and 30 mL of concentrated nitric acid, add 0.5 g of chopped carbon fiber, oxidize at 60 °C for 4 h, filter, wash with deionized water and dry to obtain oxidized carbon fiber.

[0027] (2) Add 0.5 g of oxidized carbon fiber and 3 g of toluene-2,4-diisocyanate to 120 mL of toluene solvent, heat to 80 °C in a nitrogen atmosphere, react for 4 h, filter, wash with acetone and dry to obtain isocyanate-modified carbon fiber.

[0028] (3) Add 1 g of isocyanate-modified carbon fiber and 0.25 g of diethanolamine phosphate compound (C 16 H 20 NO5P) and 0.01 g of catalyst dibutyltin dilaurate, heated to 70 °C, reacted for 8 h, filtered after the reaction, washed with ethanol and acetone and dried to obtain ethanolamine phosphate modified carbon fiber.

[0029] (4) 1.5 g of ethanolamine phosphate modified carbon fiber and 5 g of polycarbonate diol were mixed evenly, and then 2.5 g of 4,4'-diphenylmethane diisocyanate was added, and 0.04 g of catalyst dibutyltin dilaurate was added dropwise. The mixture was reacted at 75 °C in a nitrogen atmosphere for 2 h. Then the temperature was lowered to 50 °C, 0.2 g of 1,4-butanediol was added, and the reaction was carried out for 20 min. The product was placed in an oven and aged at 110 °C for 8 h to obtain a functionalized carbon fiber in situ polymerization modified polyurethane elastomer.

[0030] Example 3

[0031] (1) Prepare a mixed solution of 120 mL of concentrated sulfuric acid and 40 mL of concentrated nitric acid, add 0.5 g of chopped carbon fiber, oxidize at 70 °C for 5 h, filter, wash with deionized water and dry to obtain oxidized carbon fiber.

[0032] (2) Add 0.5 g of oxidized carbon fiber and 4.5 g of toluene-2,4-diisocyanate to 150 mL of toluene solvent, heat to 80 °C in a nitrogen atmosphere, react for 4 h, filter, wash with acetone and dry to obtain isocyanate-modified carbon fiber.

[0033] (3) Add 1 g of isocyanate-modified carbon fiber and 0.45 g of diethanolamine phosphate compound (C 16 H 20 NO5P) and 0.015 g of catalyst dibutyltin dilaurate, heated to 70 °C, reacted for 8 h, filtered after the reaction, washed with ethanol and acetone and dried to obtain ethanolamine phosphate modified carbon fiber.

[0034] (4) 2.2 g of ethanolamine phosphate modified carbon fiber and 5 g of polycarbonate diol were mixed evenly, and then 2.8 g of 4,4'-diphenylmethane diisocyanate was added, and 0.045 g of catalyst dibutyltin dilaurate was added dropwise. The mixture was reacted at 70 °C in a nitrogen atmosphere for 2.5 h. The temperature was then lowered to 45 °C, and 0.3 g of 1,4-butanediol was added. The mixture was reacted for 30 min. The product was placed in an oven and aged at 110 °C for 8 h to obtain a functionalized carbon fiber in situ polymerization modified polyurethane elastomer.

[0035] Example 4

[0036] (1) Prepare a mixed solution of 150 mL of concentrated sulfuric acid and 50 mL of concentrated nitric acid, add 0.5 g of chopped carbon fiber, oxidize at 80 °C for 8 h, filter, wash with deionized water and dry to obtain oxidized carbon fiber.

[0037] (2) Add 0.5 g of oxidized carbon fiber and 6 g of toluene-2,4-diisocyanate to 200 mL of toluene solvent, heat to 100 °C in a nitrogen atmosphere, react for 6 h, filter, wash with acetone and dry to obtain isocyanate-modified carbon fiber.

[0038] (3) Add 1 g of isocyanate-modified carbon fiber and 0.6 g of diethanolamine phosphate compound (C 16 H 20 NO5P) and 0.02 g of catalyst dibutyltin dilaurate, heated to 90 °C, reacted for 10 h, filtered after the reaction, washed with ethanol and acetone and dried to obtain ethanolamine phosphate modified carbon fiber.

[0039] (4) 3 g of ethanolamine phosphate modified carbon fiber and 5 g of polycarbonate diol were mixed evenly, and then 3.25 g of 4,4'-diphenylmethane diisocyanate was added, and 0.06 g of catalyst dibutyltin dilaurate was added dropwise. The mixture was reacted at 75 °C in a nitrogen atmosphere for 3 h, and then the temperature was reduced to 50 °C. 0.4 g of 1,4-butanediol was added and the reaction was carried out for 40 min. The product was placed in an oven and aged at 120 °C for 12 h to obtain a functionalized carbon fiber in situ polymerization modified polyurethane elastomer.

[0040] Comparative Example 1 (1) Prepare a mixed solution of 60 mL of concentrated sulfuric acid and 20 mL of concentrated nitric acid, add 0.5 g of chopped carbon fiber, oxidize at 60 °C for 3 h, filter, wash with deionized water and dry to obtain oxidized carbon fiber.

[0041] (2) Add 0.5 g of oxidized carbon fiber and 3 g of toluene-2,4-diisocyanate to 80 mL of toluene solvent, heat to 80 °C in a nitrogen atmosphere, react for 4 h, filter, wash with acetone and dry to obtain isocyanate-modified carbon fiber.

[0042] (3) 1 g of isocyanate-modified carbon fiber and 5 g of polycarbonate diol were mixed evenly, and then 2.5 g of 4,4'-diphenylmethane diisocyanate was added, and 0.03 g of catalyst dibutyltin dilaurate was added dropwise. The mixture was reacted at 75 °C in a nitrogen atmosphere for 3 h. Then the temperature was lowered to 40 °C, 0.2 g of 1,4-butanediol was added, and the reaction was carried out for 30 min. The product was placed in an oven and aged at 100 °C for 8 h to obtain a carbon fiber modified polyurethane elastomer.

[0043] Comparative Example 2 (1) 5 g of polycarbonate diol was mixed evenly, and then 2.5 g of 4,4'-diphenylmethane diisocyanate was added, and 0.03 g of catalyst dibutyltin dilaurate was added dropwise. The mixture was reacted at 65 °C in a nitrogen atmosphere for 2 h. Then the temperature was lowered to 45 °C, 0.2 g of 1,4-butanediol was added, and the reaction was continued for 30 min. The product was placed in an oven and aged at 110 °C for 12 h to obtain a polyurethane elastomer.

[0044] The functionalized carbon fiber was in-situ polymerized to modify the polyurethane elastomer to make a square specimen with a size of 1 cm×1 cm×0.2 cm. The thermal decomposition temperature and residual carbon rate were tested in a TGA-601 thermogravimetric analyzer with a maximum test temperature of 800 ℃.

[0045] The polyurethane elastomer sample was placed in a PX-01-005 oxygen index tester to test the limiting oxygen index and flame retardant properties.

[0046]

Claims

1. A method for preparing a functionalized carbon fiber in-situ polymerization-modified polyurethane elastomer, characterized in that: The method comprises the following steps: (1) preparing a mixed solution of concentrated sulfuric acid and concentrated nitric acid, adding chopped carbon fibers, and oxidizing them at 50-80 °C for 3-8 h to obtain oxidized carbon fibers; (2) adding oxidized carbon fiber and toluene-2,4-diisocyanate to a toluene solvent, heating the mixture to 75-100° C. in a nitrogen atmosphere to obtain isocyanate-modified carbon fiber; (3) Add isocyanate modified carbon fiber and diethanolamine phosphate compound (C 16 H 20 NO5P) and a catalyst dibutyltin dilaurate are reacted at elevated temperature to obtain ethanolamine phosphate modified carbon fiber; (4) The ethanolamine phosphate modified carbon fiber and polycarbonate diol are mixed evenly, and then 4,4'-diphenylmethane diisocyanate is added, and the catalyst dibutyltin dilaurate is added dropwise. The mixture is reacted at 65-75 °C in a nitrogen atmosphere for 2-3 h, and then the temperature is reduced to 40-50 °C, 1,4-butanediol is added, and the reaction is carried out for 20-40 min. The product is placed in an oven and aged at 100-120 °C for 6-12 h to obtain a functionalized carbon fiber in situ polymerization modified polyurethane elastomer.

2. The method for preparing a functionalized carbon fiber in-situ polymerization-modified polyurethane elastomer according to claim 1, characterized in that: In the step (3), the isocyanate-modified carbon fiber is 100 parts, the diethanolamine phosphate compound is 15-60 parts, and the dibutyltin dilaurate is 0.5-2 parts by weight.

3. The method for preparing a functionalized carbon fiber in-situ polymerization-modified polyurethane elastomer according to claim 1, characterized in that: The reaction in step (3) is carried out at 60-90° C. for 4-10 h.

4. The method for preparing a functionalized carbon fiber in-situ polymerization-modified polyurethane elastomer according to claim 1, characterized in that: In the step (4), the weight ratio of ethanolamine phosphate modified carbon fiber is 0.5-3 parts, polycarbonate diol is 100 parts, 4,4'-diphenylmethane diisocyanate is 40-65 parts, dibutyltin dilaurate is 0.5-1.2 parts, and 1,4-butanediol is 3-8 parts.

5. A functionalized carbon fiber in-situ polymerization modified polyurethane elastomer, characterized in that: The functionalized carbon fiber in-situ polymerization-modified polyurethane elastomer is applied to flame-retardant polyurethane materials.

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