A method for utilizing byproduct resins in decommissioned carbon fiber reinforced resin matrix composites and the preparation of an anti-corrosion coating.

Abstract

This invention provides a method for utilizing byproduct resins in decommissioned carbon fiber reinforced resin matrix composites and the preparation of an anti-corrosion coating. First, in a molten salt bath, the decommissioned carbon fiber reinforced resin matrix composite is mixed with molten salt containing CeO2, heated and kept at a constant temperature to separate the carbon fibers and collect the liquid phase product. The liquid phase product is then distilled to separate an aqueous phase and a phenol-rich phase. Epichlorohydrin is added to the phenol-rich phase for conditioning. Finally, epoxy resin and a solvent are added to the conditioned phenol-rich phase to obtain a metal anti-corrosion paint. The obtained metal anti-corrosion paint is then applied to a metal surface and cured to obtain an anti-corrosion layer. Compared with existing technologies, the Ce-based catalyst of this invention can effectively increase the reaction rate, reduce the yield of coke, increase the yield of liquid phase products, and has good anti-coking properties. This invention also uses phenol-rich oil prepared by cracking, which is then used as a metal anti-corrosion coating.

Description

Technical Field

[0001] This invention belongs to the field of resin material recycling, specifically relating to a method for utilizing byproduct resins in decommissioned carbon fiber reinforced resin matrix composites and the preparation of an anti-corrosion coating. Background Technology

[0002] Carbon fiber, with its excellent low-density and high-strength properties, has been widely used in aerospace, wind power generation, and hydrogen storage containers in recent years. As the application of carbon fiber increases dramatically year by year, the necessity of its recycling is becoming increasingly prominent. In the carbon fiber matrix market, thermosetting resins occupy a dominant position due to their superior mechanical properties and synthetic advantages. Their crosslinking characteristics give their synthesized carbon fiber composites superior overall performance. However, the stable three-dimensional network structure formed by crosslinking makes it more difficult to break down during recycling, thus making the targeted recycling of carbon fiber a challenge.

[0003] To address this challenge, existing recycling technologies often employ more drastic methods to break down the three-dimensional network structure. Taking pyrolysis technology, currently the only technology with preliminary commercial application, as an example, the products generated after the pyrolysis of thermosetting resins have complex compositions, poor homogeneity, and low economic value, making it difficult to develop high-value utilization pathways.

[0004] The patent CN 108779284 A, published on November 9, 2018, entitled "Method for Recovering Decomposition Products of Thermosetting Resin Cured Materials and Method for Manufacturing Recycled Materials," discloses a process of contacting a sample containing thermosetting resin cured materials with a treatment liquid containing an alkali metal compound and an alcohol solvent to decompose and dissolve the thermosetting resin cured materials; a process of mixing the treatment liquid containing the decomposition products of the thermosetting resin cured materials with an acidic aqueous solution and separating it into an aqueous layer and an organic layer containing the decomposition products; and a process of recovering the organic layer. However, it does not disclose how to solve the problem of homogenization of resin decomposition products.

[0005] If efficient dissociation of resin in composite materials can be achieved and key components of resin decomposition products can be targetedly enhanced, the economic value of by-product resins will be further improved, and the full recycling of carbon fiber composite materials will be promoted. Summary of the Invention

[0006] The purpose of this invention is to provide a method for utilizing byproduct resins in decommissioned carbon fiber reinforced resin matrix composites and to prepare an anti-corrosion coating. The method involves recovering carbon fibers using cerium oxide and molten salt to obtain a phenol-rich phase, followed by conditioning with epichlorohydrin, compounding with epoxy resin, and curing to obtain an anti-corrosion coating suitable for metal corrosion protection. This invention effectively solves the problems of complex composition, poor homogeneity, and low economic value of products generated after the thermal decomposition of thermosetting resins. The method for utilizing byproduct resins in decommissioned carbon fiber reinforced resin matrix composites provided by this invention achieves efficient resin dissociation and targeted enhancement of key components in resin decomposition products.

[0007] The specific technical solution of this invention is as follows:

[0008] A method for utilizing the byproduct resin in a decommissioned carbon fiber reinforced resin matrix composite material, specifically as follows:

[0009] 1) In a molten salt bath, the decommissioned carbon fiber reinforced resin matrix composite material is mixed with molten salt containing CeO2, heated and kept at a constant temperature, the carbon fiber is separated, and the liquid phase product is collected;

[0010] 2) The liquid phase product is distilled to separate the aqueous phase and the phenol-rich phase;

[0011] 3) Add epichlorohydrin to the phenol-rich phase and condition it;

[0012] 4) Add epoxy resin and solvent to the conditioned phenol-rich phase to obtain metal anti-corrosion paint.

[0013] In step 1), the mass ratio of the decommissioned carbon fiber reinforced resin matrix composite to the molten salt containing CeO2 is greater than 10:1.

[0014] In step 1), the carbon fiber reinforced resin matrix composite material refers to a carbon fiber and epoxy resin matrix composite material; preferably, the carbon fiber reinforced resin matrix composite material is selected from carbon fiber reinforced resin matrix composite materials used in hydrogen storage containers or wind turbine blades.

[0015] In step 1), the molten salt contains CeO2, and the mass ratio of CeO2 in the molten salt is 5-10%, preferably 8%.

[0016] In step 1), the molten salt is selected from one or more of chloride salts, alkali salts or carbonate salts. Preferably, the molten salt is selected from ZnCl2-KCl molten salt or Li2CO3-Na2CO3-K2CO3 molten salt.

[0017] In step 1), the heating and heat preservation temperature is 400-800℃, and the time is 0.5-1h.

[0018] In step 1), the separation of carbon fibers specifically involves: setting up a winding device in the molten salt pool, which can rotate clockwise at a low speed to wind the carbon fibers onto the winding device, and then the winding device leaves the molten salt pool, enters the water pool, and rotates counterclockwise to unwind the fibers, thus completing the recovery of carbon fibers after the molten salt electrolysis reaction.

[0019] In step 1), the liquid phase product is obtained by condensation separation.

[0020] In step 2), the liquid product is distilled to separate the aqueous phase and the phenol-rich phase. The aqueous phase has a boiling point of 100°C and is discarded. The phenol-rich phase has a boiling point of 200-300°C and is collected for further use.

[0021] In step 3), epichlorohydrin is added to the phenol-rich phase, with a mass ratio of phenol-rich phase to epichlorohydrin of 1:6 to 1:10. The phenol-rich phase consists of p-isopropylphenol, bisphenol A, bisphenol F, etc. The purpose of step 3) is to enable it to undergo a polymerization reaction to generate bisphenol A epoxy resin.

[0022] Step 3) specifically involves: mixing epichlorohydrin and the phenol-rich phase, then heating in a water bath to 70-80°C. Adding a 25-30 wt% sodium hydroxide solution at a total volume ratio of epichlorohydrin and phenol-rich phase to sodium hydroxide solution of 1:1, and maintaining the water bath for 2 hours. Adding an equal volume of benzene and distilled water, stirring and mixing, and then allowing the mixture to stand and separate into layers. Distilling the resulting oily substance to remove water, benzene, and excess epichlorohydrin yields the conditioned phenol-rich phase.

[0023] In step 4), the mass ratio of the conditioned phenolic phase, epoxy resin, and solvent is 1:10:1.

[0024] In step 4), the epoxy resin is selected from E-44 or E-51.

[0025] In step 4), the solvent is selected from strongly polar solvents, preferably acetone.

[0026] This invention uses a CeO2 catalyst, dispersed at a mass ratio of 5-10% in a molten salt system, to catalyze the cracking of a resin matrix, preparing a phenol-rich component. This component is then fractionated according to its boiling point and used as a raw material for re-resin preparation. This invention develops methods for preparing metal coatings and recombining fibers to manufacture composite materials. Furthermore, this invention mixes the distilled phenol-rich phase with epichlorohydrin, and then with epoxy resin to produce an anti-corrosion paint, achieving the recycling and reuse of decommissioned materials.

[0027] The present invention provides an anti-corrosion coating, which is obtained by using the method of utilizing the byproduct resin in the above-mentioned decommissioned carbon fiber reinforced resin matrix composite material, coating the metal surface with the anti-corrosion paint, and curing it to obtain the anti-corrosion coating.

[0028] The curing process involves heating to 150-180℃ at a rate of 3-5℃ / min and holding at that temperature for 0.5-1h.

[0029] The thickness of the anti-corrosion coating is 3-5 mm.

[0030] The metal anti-corrosion paint prepared by utilizing the byproduct resin in the decommissioned carbon fiber reinforced resin matrix composite provided by this invention has good anti-corrosion effect and stable coating properties after curing.

[0031] In this invention, when the fiber is removed, a rotating machine is set in the molten salt pool. The machine can rotate clockwise at a low speed to wind the fiber onto the machine. Then the machine leaves the molten salt pool, enters the water pool, and rotates counterclockwise to remove the fiber. After the molten salt reaction is completed, the fiber is recovered and removed.

[0032] Compared with existing technologies, the addition of a Ce-based catalyst to the molten salt system in this invention effectively increases the reaction rate, reduces coke yield, increases the yield of liquid-phase products, and exhibits good anti-coking properties. It demonstrates strong selectivity in the pyrolysis of the resin matrix, lowering the energy barrier and selectively breaking CO ether single bonds, thereby enabling the resin matrix to depolymerize and generate more short-chain compounds. Furthermore, it possesses high oxygen exchange and storage capacity, effectively reducing the amount of free oxygen and promoting the formation of hydroxyl radicals through thermal activation, thus increasing the oxygen-containing component content in the liquid-phase products. Cerium oxide particles exhibit high dispersibility and suspension stability in viscous liquids; therefore, molten salt and cerium oxide particles can be combined to form a more stable and efficient dispersion system, thereby improving the efficiency of resin catalytic pyrolysis. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Unless otherwise specified, all test materials and reagents used in the following examples are commercially available.

[0035] Unless otherwise specified in the embodiments, the techniques or conditions described in the literature in this field or in accordance with the product manual may be followed.

[0036] Example 1

[0037] A method for utilizing the byproduct resin in a decommissioned carbon fiber reinforced resin matrix composite material, specifically as follows:

[0038] 1) In a molten salt pool, ZnCl2-KCl molten salt containing 8wt% CeO2 is first heated to a preset temperature of 600℃ and held for 1 hour. Then, decommissioned carbon fiber reinforced epoxy resin composite material is added and held at 600℃ for 0.5 hours, yielding a liquid phase product with a yield of 63%. The mass ratio of decommissioned carbon fiber reinforced resin composite material to CeO2-containing molten salt is 12:1. The carbon fiber reinforced resin composite material used is wind turbine blade material. Taking a wind turbine blade with a length of 50 meters as an example, the mass proportion of carbon fiber composite material in the main beam is about 20%, and the ratio of carbon fiber to resin is about 7:3. Simultaneously, a winding device is installed in the molten salt pool. This device rotates clockwise at a low speed to wind the carbon fiber onto the winding device. Then, the winding device leaves the molten salt pool, enters a water pool, and rotates counterclockwise to unwind the fiber, completing the recovery of carbon fiber after the molten salt electrolysis reaction.

[0039] 2) Distill the liquid product obtained in step 1) and condense it to separate the aqueous phase and the phenol-rich phase; discard the aqueous phase and the phenol-rich phase accounts for 71% of the liquid product.

[0040] 3) Add epichlorohydrin to the phenol-rich phase at a mass ratio of 1:6. Heat in a water bath to 80°C. Add a 30wt% sodium hydroxide solution at a total volume ratio of epichlorohydrin to phenol-rich phase to sodium hydroxide solution of 1:1. Maintain the water bath for 2 hours. Add an equal volume of benzene and distilled water, stir to mix, and allow to stand for separation. Distill the resulting oily substance to remove water, benzene, and excess epichlorohydrin, yielding the conditioned phenol-rich phase.

[0041] 4) Add epoxy resin E-44 and solvent acetone to the conditioned phenol-rich phase, wherein the mass ratio of the conditioned phenol-rich phase, epoxy resin and solvent is 1:10:1, mix well, and obtain metal anti-corrosion paint.

[0042] The metal anti-corrosion paint prepared in Example 1 was applied to a metal surface, and the temperature was increased to 150°C at a rate of 3-5°C / min and held at that temperature for 1 hour to cure, thus obtaining an anti-corrosion coating. The thickness of the formed anti-corrosion coating was 4 mm.

[0043] Comparative Example 1

[0044] A method for utilizing the byproduct resin in a decommissioned carbon fiber reinforced resin matrix composite material, specifically as follows:

[0045] 1) In a molten salt bath, ZnCl2-KCl molten salt is first heated to a preset temperature of 600℃ and held for 1 hour. Then, decommissioned carbon fiber reinforced epoxy resin matrix composite material is added and held at 600℃ for 0.5 hours, yielding a liquid phase product with a yield of 37%. The mass ratio of decommissioned carbon fiber reinforced resin matrix composite material to molten salt is 12:1, and the carbon fiber reinforced resin matrix composite material used is the same as in Example 1. Simultaneously, a winding device is installed in the molten salt bath, capable of rotating clockwise at low speed to wind the carbon fiber onto the device. The winding device then leaves the molten salt bath, enters a water tank, and rotates counterclockwise to unwind the fiber, completing the recovery of carbon fiber after the molten salt electrolysis reaction.

[0046] 2) The liquid phase product is distilled and condensed to separate the aqueous phase and the phenol-rich phase; the aqueous phase is discarded, and the phenol-rich phase accounts for 31% of the liquid phase product.

[0047] 3) Add epichlorohydrin to the phenol-rich phase, and the conditioning reaction process is the same as in Example 1;

[0048] 4) Add epoxy resin and solvent to the conditioned phenol-rich phase. The specific raw materials and methods are the same as in Example 1 to obtain metal anti-corrosion paint.

[0049] Following the same method and parameters as in Example 1, the metal anti-corrosion paint prepared in Comparative Example 1 was applied to the metal surface and cured to obtain an anti-corrosion coating.

[0050] A comparison of Example 1 and Comparative Example 1 shows that the molten salt system in Example 1, containing CeO2, exhibits a high yield of liquid-phase products and a high proportion of phenol-rich components after distillation. The reaction only requires 0.5 hours, indicating that the CeO2-containing catalyst of this invention can effectively improve the reaction rate and increase the yield of liquid-phase products. It also demonstrates strong selectivity in the pyrolysis of the resin matrix, lowering the energy barrier and selectively breaking CO ether single bonds. This allows the resin matrix to depolymerize and generate more short-chain compounds (phenol-rich phase), which is beneficial for the recycling of numerical materials.

[0051] Example 2

[0052] A method for utilizing the byproduct resin in a decommissioned carbon fiber reinforced resin matrix composite material, specifically as follows:

[0053] 1) In a molten salt bath, a Li₂CO₃-Na₂CO₃-K₂CO₃ molten salt containing 8 wt% CeO₂ is first heated to a preset temperature of 700°C and held for 1 hour. Then, a decommissioned carbon fiber reinforced epoxy resin composite material is added and held for 0.5 hours, yielding a liquid phase product with a yield of 84%. The mass ratio of the decommissioned carbon fiber reinforced resin composite material to the Li₂CO₃-Na₂CO₃-K₂CO₃ molten salt containing 8 wt% CeO₂ is 15:1. The carbon fiber reinforced resin composite material used is wind turbine blade material, as in Example 1. Simultaneously, a winding device is installed in the molten salt bath, capable of rotating clockwise at low speed to wind the carbon fiber onto the device. The winding device then leaves the molten salt bath, enters a water tank, and rotates counterclockwise to unwind the fiber, completing the recovery of the carbon fiber after the molten salt electrolysis reaction.

[0054] 2) The liquid product is distilled and condensed to separate the aqueous phase and the phenol-rich phase; the aqueous phase is discarded, and the phenol-rich phase accounts for 83% of the liquid product.

[0055] 3) Add epichlorohydrin to the phenol-rich phase at a mass ratio of 1:10. Heat in a water bath to 70°C. Add a 25wt% sodium hydroxide solution at a total volume ratio of epichlorohydrin to phenol-rich phase to sodium hydroxide solution of 1:1. Maintain the water bath for 2 hours. Add an equal volume of benzene and distilled water, stir to mix, and allow to stand for separation. Distill the resulting oily substance to remove water, benzene, and excess epichlorohydrin, yielding the conditioned phenol-rich phase.

[0056] 4) Add E-51 epoxy resin and solvent acetone to the conditioned phenol-rich phase. The mass ratio of E-51 epoxy resin to solvent acetone in the conditioned phenol-rich phase is 1:10:1. Stir and mix well to obtain metal anti-corrosion paint.

[0057] The metal anti-corrosion paint prepared in Example 2 was applied to the metal surface, and the temperature was increased to 180°C at a rate of 5°C / min and held for 0.5h to obtain the anti-corrosion coating.

[0058] Comparative Example 2

[0059] A method for utilizing the byproduct resin in a decommissioned carbon fiber reinforced resin matrix composite material, specifically as follows:

[0060] 1) In a molten salt bath, Li2CO3-Na2CO3-K2CO3 molten salt is first heated to a preset temperature of 700℃ and held for 1 hour. Then, decommissioned carbon fiber reinforced epoxy resin composite material is added and held for 0.5 hours, yielding a liquid phase product with a yield of 52%. The mass ratio of decommissioned carbon fiber reinforced resin composite material to molten salt is 15:1, and the carbon fiber reinforced resin composite material used is the same as in Example 2. Simultaneously, a winding device is installed in the molten salt bath, capable of rotating clockwise at low speed to wind the carbon fiber onto the device. The winding device then leaves the molten salt bath, enters a water tank, and rotates counterclockwise to unwind the fiber, completing the recovery of carbon fiber after the molten salt electrolysis reaction.

[0061] 2) The liquid product is distilled and condensed to separate the aqueous phase and the phenol-rich phase; the aqueous phase is discarded, and the phenol-rich phase accounts for 44% of the liquid product.

[0062] 3) Add epichlorohydrin to the phenol-rich phase and condition it, following the same procedure as in Example 2.

[0063] 4) Add epoxy resin and solvent to the conditioned phenol-rich phase, and obtain metal anti-corrosion paint according to the same raw materials and methods as in Example 2.

[0064] Following the same parameters and methods as in Example 2, the metal anti-corrosion paint prepared in Comparative Example 2 was applied to the metal surface and cured to obtain an anti-corrosion coating.

[0065] A comparison of Example 2 and Comparative Example 2 shows that the molten salt in Example 2, containing 8% CeO2, exhibits a high yield of liquid-phase products and a high proportion of phenol-rich components after distillation. The reaction only requires 0.5 hours, indicating that the CeO2-containing catalyst of this invention can effectively improve the reaction rate and increase the yield of liquid-phase products. It also demonstrates strong selectivity in the pyrolysis of the resin matrix, lowering the energy barrier and selectively breaking CO ether single bonds. This allows the resin matrix to depolymerize and generate more short-chain compounds (phenol-rich phase), which is beneficial for the recycling of numerical materials.

[0066] The above description of the embodiments is intended to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for utilizing byproduct resin in decommissioned carbon fiber reinforced resin matrix composites, characterized in that, The utilization method includes the following steps: 1) In a molten salt bath, the decommissioned carbon fiber reinforced resin matrix composite material is mixed with molten salt containing CeO2, heated and kept at a constant temperature, the carbon fiber is separated, and the liquid phase product is collected; 2) The liquid phase product is distilled to separate the aqueous phase and the phenol-rich phase; 3) Add epichlorohydrin to the phenol-rich phase and condition it; 4) Add epoxy resin and solvent to the conditioned phenol-rich phase to obtain a metal anti-corrosion paint; In step 1), the mass ratio of the decommissioned carbon fiber reinforced resin matrix composite to the molten salt containing CeO2 is greater than 10:1; The molten salt containing CeO2 has a CeO2 content of 5-10% by mass. In step 3), epichlorohydrin is added to the phenol-rich phase, and the mass ratio of the phenol-rich phase to epichlorohydrin is 1:6-1:

10.

2. The utilization method according to claim 1, characterized in that, In step 1), the molten salt is selected from one or more of chloride salts, alkali salts, or carbonate salts.

3. The utilization method according to claim 1, characterized in that, In step 1), the heating and heat preservation temperature is 400-800℃ and the time is 0.5-1h.

4. The utilization method according to claim 1, characterized in that, Step 3) Specifically: Mix epichlorohydrin and phenol-rich phase, then heat in a water bath to 70-80℃. Add sodium hydroxide solution with a mass concentration of 25-30wt% at a total volume ratio of epichlorohydrin and phenol-rich phase to sodium hydroxide solution of 1:

1. Maintain the water bath for 2 hours. Add an equal volume of benzene and distilled water, stir and mix, and then allow to stand for separation. Distill the oily substance obtained from the separation to remove water, benzene and excess epichlorohydrin, thus obtaining the conditioned phenol-rich phase.

5. The method of utilization according to claim 1, characterized in that, In step 4), the mass ratio of the conditioned phenolic phase, epoxy resin, and solvent is 1:10:

1.

6. The utilization method according to claim 1 or 5, characterized in that, In step 4), the epoxy resin is selected from E-44 or E-51; the solvent is selected from acetone.

7. An anti-corrosion coating, characterized in that, The metal anti-corrosion paint obtained by utilizing the byproduct resin in the decommissioned carbon fiber reinforced resin matrix composite material according to any one of claims 1-6 is applied to the metal surface and cured to obtain an anti-corrosion coating.