Method for decomposing and recycling epoxy resin-based carbon fiber composite material

Abstract

This invention relates to a superior method for decomposing and recycling epoxy resin carbon fiber composite materials. The method involves mixing carbon fiber sheets with an alkaline solution, heating in a sealed environment, and then washing and drying to obtain intact carbon fibers. The filtrate is then separated to obtain bisphenol A salt compounds. This method can be used for the recovery of carbon fibers from carbon fiber sheets and has broad application prospects.

Description

Technical Field

[0001] This invention relates to the field of decomposition and recycling of epoxy resin-based carbon fiber composite materials, specifically to a method for decomposing and recycling epoxy resin-based carbon fiber composite materials, belonging to the field of functional polymer materials technology. Background Technology

[0002] Epoxy resin-based carbon fiber sheets are widely used in aerospace, new energy vehicles, and high-end sporting goods due to their high strength, high modulus, lightweight, and excellent fatigue resistance. Applications include aircraft fuselage components, wind turbine blade load-bearing structures, and racing car chassis. However, the recycling of these composite materials faces significant challenges. The core problem lies in the extremely strong chemical stability of the three-dimensional cross-linked network formed after epoxy resin curing, and its tight interfacial bonding with carbon fiber. This structure makes epoxy resin carbon fiber sheets virtually non-degradable in the natural environment, leading to a continuous accumulation of decommissioned products. Traditional disposal methods have significant drawbacks: landfilling not only wastes land resources, but the residual curing agent in the epoxy resin may also slowly leach out and pollute the soil; simple incineration, while reducing volume, releases toxic gases such as furan and benzene compounds at high temperatures, and the carbon fiber is easily oxidized during incineration, losing its recycling value.

[0003] Currently, the mainstream processing methods include pyrolysis, mechanical crushing, and chemical solvent methods. Pyrolysis decomposes epoxy resin by heating in an inert atmosphere (400-800℃), which can recover carbon fibers, but requires large equipment investments and consumes a lot of energy. Mechanical crushing uses the crushed waste as a low-value filler, but the fiber length is severely damaged, making it unusable for high-end structural components, and the resin matrix is ​​completely wasted. Chemical solvent methods use strong acids or organic solvents to dissolve the resin, which can preserve the strength of the carbon fibers, but the solvent costs are high, recycling is difficult, and it easily causes secondary pollution. These methods either cannot efficiently recover high-value carbon fibers or make it difficult to achieve the recycling of the resin matrix. Therefore, developing a waste carbon fiber epoxy resin board recycling technology that is both environmentally friendly and economical has become an urgent need for the industry. Summary of the Invention

[0004] The purpose of this invention is to provide a hydrolysis and recycling method for epoxy resin carbon fiber composite materials. This method has the advantages of simple process, good decomposition effect, high recycling efficiency, controllable process and low cost. The hydrolyzed glass fiber has good integrity, is easy to peel off, and can realize the recycling of polyester, which has broad application prospects.

[0005] To achieve the objectives of this invention, the following technical solutions are provided: A method for hydrolyzing and recycling epoxy resin-based carbon fiber composite materials is characterized by the following steps: mixing epoxy resin-based carbon fiber boards with alkaline solution, heating in a sealed environment, and then washing and drying to obtain complete carbon fibers; separating the filtrate to obtain bisphenol A salt compounds.

[0006] Furthermore, the alkaline solution used for hydrolysis is prepared by mixing a strong base and a weak base in a certain proportion.

[0007] Furthermore, the strong base used in preparing the alkaline solution is sodium hydroxide, and the weak base is sodium carbonate.

[0008] Furthermore, the mass ratio of strong base to weak base in the prepared alkaline solution is 1:1~5.

[0009] Furthermore, the ratio of carbon fiber plate to alkaline solution during the decomposition of the carbon fiber plate is 1g: 5 ml to 50 ml, preferably 1g: 10 ml to 20 ml.

[0010] Furthermore, the reaction conditions for the decomposition of the epoxy resin carbon fiber composite material are as follows: temperature is 160 ℃~220 ℃, preferably 190 ℃~220 ℃; time is 4 h~24 h, preferably 8 h~16 h.

[0011] Compared with the prior art, the present invention has the following beneficial effects: The hydrolysis and recycling method for epoxy resin-based carbon fiber composite materials described in this invention has low raw material costs, low carbon fiber loss rate, and good mechanical properties. It can be used for the recycling and reuse of waste epoxy resin-based carbon fiber composite materials, is easy to promote and use, and has broad application prospects. Detailed Implementation

[0012] The present invention will be further described below through specific embodiments. The following examples are intended to illustrate the invention and not to further limit it. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0013] Implementation Case 1 1.444g of carbon fiber composite material, 0.131g of sodium hydroxide, and 0.129g of sodium carbonate were weighed. The sodium hydroxide and sodium carbonate were dissolved in 30ml of deionized water to prepare an alkaline solution. The raw materials were added to a reaction vessel and then placed in an oven. The oven temperature was adjusted to 210℃, and the reaction time was 8 hours under sealed conditions. After the reaction was completed, the carbon fiber was obtained after filtration, washing, and drying. The mechanical properties of the recovered carbon fiber were 74% of those of the original fiber.

[0014] Implementation Case 2 Weigh 1.461 g of carbon fiber composite material, 0.133 g of sodium hydroxide, and 0.099 g of sodium carbonate. Dissolve the sodium hydroxide and sodium carbonate in 30 ml of deionized water to prepare an alkaline solution. Add the raw materials to a reaction vessel and then place it in an oven. Adjust the oven temperature to 210 ℃ and react for 8 hours in a sealed environment. After the reaction is complete, filter, wash, and dry to obtain carbon fiber. The mechanical properties of the recovered carbon fiber are 76% of those of the original fiber.

[0015] Implementation Case 3 Weigh out 1.425 g of carbon fiber, 0.137 g of sodium hydroxide, and 0.126 g of sodium carbonate. Dissolve the sodium hydroxide and sodium carbonate in 30 ml of deionized water to prepare an alkaline solution. Add the raw materials to a reaction vessel and then place it in an oven. Adjust the oven temperature to 210 ℃ and react for 8 hours in a sealed environment. After the reaction is complete, filter, wash, and dry to obtain carbon fiber. The mechanical properties of the recovered carbon fiber are 71% of those of the original fiber.

Claims

1. A method for decomposing and recycling an epoxy resin-based carbon fiber composite material, characterized by the following steps: After mixing epoxy resin-based carbon fiber sheets with alkaline solution, the mixture is heated in a sealed environment, and then washed and dried to obtain complete carbon fibers. The filtrate is then separated to obtain bisphenol A salt compounds.

2. The method for decomposing and recycling epoxy resin carbon fiber composite materials as described in claim 1, characterized in that... The alkaline solution used for hydrolysis is prepared by mixing strong and weak bases in a certain proportion.

3. The method for decomposing and recycling epoxy resin carbon fiber composite materials as described in claim 2, characterized in that... The strong base used to prepare the alkaline solution is sodium hydroxide, and the weak base is sodium carbonate.

4. The method for decomposing and recycling epoxy resin-based carbon fiber composite materials as described in claim 3, characterized in that... The mass ratio of strong base to weak base is 1:1~5.

5. The method for recycling epoxy resin-based carbon fiber plates as described in claim 1, characterized in that... The ratio of carbon fiber sheet to alkaline solution during carbon fiber sheet decomposition is 1g:5 ml~50 ml, preferably 1g:10 ml~20 ml.

6. The method for decomposing and recycling epoxy resin carbon fiber composite materials as described in claim 1, characterized in that... The reaction conditions for the decomposition of epoxy resin carbon fiber composite material are as follows: temperature is 160 ℃~220 ℃, preferably 190 ℃~220 ℃; time is 4 h~24 h, preferably 8 h~16 h.