Method for recovering fiber from epoxy resin/fiber composite material

Abstract

The invention provides a method for recovering fiber from an epoxy resin / fiber composite material, which comprises the following steps: mixing the first epoxy resin / fiber composite material with reaction mother liquor for obtaining a first mixed material; heating the mixed material for decomposing the first epoxy resin / fiber composite material; and recovering the fiber from decomposition products of the first epoxy resin / fiber composite material, wherein the reaction mother liquor comprises phenolic compounds, water and a catalyst; and the catalyst in the reaction mother liquor is an alkali metal hydroxide. The method adopts the solvent decomposition method for decomposing the epoxy resin / fiber composite material without the need of carrying out breaking or smashing and other pretreatment on the epoxy resin / fiber composite material, thereby reducing the impacts on the mechanical properties of the fiber, reducing the loss of the mechanical properties of the fiber, being more conductive to carrying out plastic injection molding, hot compression molding or making into non-woven fabric for further application. Simultaneously, the method provided by the invention can realize higher decomposition efficiency of resin and lower cost.

Description

technical field [0001] The invention relates to the technical field of recycling waste polymers, in particular to a method for recycling fibers from epoxy resin / fiber composite materials. Background technique [0002] Epoxy resin composite materials, especially fiber-reinforced epoxy resin composite materials, have the advantages of high strength, light weight, heat resistance, chemical resistance, and high reliability, and are widely used in electronic power, transportation, aerospace, sports equipment, wind power, etc. Power generation and other fields. However, this kind of material has a certain service life, and it has a three-dimensional cross-linked network structure, so it cannot be re-melted and re-molded after being discarded. The traditional method of disposing of epoxy resin composite waste is landfill and incineration. These two treatment methods not only pollute the environment, but also waste materials. For example, fiber production in fiber-reinforced epoxy ...

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Problems solved by technology

Among them, physical recycling is to mechanically crush waste materials and use them as fillers to make recycled products, but this method is only applicable to uncontaminated materials, and the use value of recycled products is low; heat energy recovery refers to directly burning waste materials to obtain heat energy , suitable for waste materials with high resin content, but at the same time the fibers in them are also burned as fuel, wasting resources; chemical recycling is to decompose the matrix resin in waste materials into small molecules by heating or solvents so as to decompose fibers or other inorganic For material recovery, the pyrolysis method requires a higher temperature, and the properties of the fibers obtained after decomposition are greatly reduced. However, by solvent decomposition of waste materials, damage to the fibers in waste materials can be avoided by crushing or pulverization, and fibers with less loss of mechanical properties can be obtained. , and the resin can be recycled at the same time, therefore, the solvent decomposition method is one of the research hotspots in the recycling method of waste epoxy resin composite materials

[0004] The prior art has disclosed a variety of methods for solvent decomposition and recovery of waste epoxy resin composite materials. For example, Chinese patent document CN03132542.4 discloses a method for decomposing waste epoxy resin composite materials using nitric acid solution as a solvent. However, nitric acid The application range of the solution is limited, and it is only suitable for epoxy resin composite materials cured by amine curing agents; Chinese patent document CN200610151145.7 discloses a partially hydrogenated aromatic compound, mainly tetralin or decahydronaphthalene as a solvent for decomposition The method of thermosetting epoxy resin and its composite material, but the average loss of tensile strength of fiber monofilament obtained by this method is 31%, which is not conducive to the reuse of fibers; Chinese patent document CN200710144538.X discloses a method using water as a solvent , a method for decomposing thermosetting epoxy resin composite materials under high temperature and high pressure, but the amount of catalyst used in this method is large, and the requirements for reaction conditions are relatively high; Chinese patent document CN200910046524. The substance is a catalyst to decompose thermosetting epoxy resin or its composite materials, but heteropolyacid catalysts such as phosphotungstic acid, tungstosilicic acid or copper molybdophosphoric acid are expensive and the recovery cost is high

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