CN-121975086-A - Solvent-free preparation method and recovery method of dynamic cross-linked epoxy resin

Abstract

The invention relates to the technical field of high polymer materials, and in particular provides a solvent-free preparation method and a recovery method of dynamic cross-linked epoxy resin, wherein the preparation method comprises the steps of reacting diamine compound with olefine acid ester, then reacting with hydrazine hydrate to prepare oily hydrazide monomer, and then carrying out solvent-free mixing, defoaming, injection molding and curing on the monomer, modified amine curing agent, blocked isocyanate and epoxy resin monomer according to a specific molar ratio to obtain epoxy resin based on amido urea dynamic bond; the recovery method comprises the steps of degrading the obtained epoxy resin, diamine compound and organic solvent into degradation liquid under heating, and then adding epoxy resin monomer into the degradation liquid to obtain regenerated resin after curing. The invention realizes the green and efficient preparation of the epoxy resin, and breaks through the improvement of the tensile strength of the recovered resin by more than 28.56 percent, the improvement of the glass transition temperature by more than 45 percent, and the closed loop recovery of the performance upgrading.

Inventors

• XIA HESHENG
• ZHOU LIN
• NIE YUAN
• ZHANG ZAIXUE
• GAO HONG

Assignees

• 四川大学
• 中航(成都)无人机系统股份有限公司

Dates

Publication Date

20260505

Application Date

20260120

Claims (9)

1. 1. A solvent-free preparation method of a dynamic cross-linked epoxy resin is characterized by comprising the following steps: the method comprises the steps of mixing oily hydrazide monomer, modified amine curing agent, blocked isocyanate and epoxy resin monomer in a solvent-free manner to form a uniform mixture, defoaming, injection molding and curing to obtain the dynamic cross-linked epoxy resin, wherein the oily hydrazide monomer is prepared by reacting diamine compound with olefine acid ester and then reacting with hydrazine hydrate.
2. 2. The solvent-free preparation method of the dynamic cross-linked epoxy resin according to claim 1, wherein the molar ratio of the oily hydrazide monomer to the modified amine curing agent to the blocked isocyanate to the epoxy resin monomer is 1:1-2:1-1.5:4-6.
3. 3. The solvent-free process for producing a dynamically crosslinked epoxy resin according to claim 1, wherein the diamine compound is one or more selected from the group consisting of ethylenediamine, hexamethylenediamine, m-xylylenediamine, 1, 3-xylylenediamine, isophoronediamine, 4 '-diaminodiphenylmethane, 4' -diaminodiphenylsulfone, and polyetheramine, and the mixture is mixed in any ratio.
4. 4. The solvent-free preparation method of the dynamic cross-linked epoxy resin according to claim 1, wherein the acrylic acid ester is formed by mixing one or two or more selected from methyl acrylate, ethyl acrylate, butyl acrylate, methyl 3-butenoate and ethyl 2-butenoate in any proportion.
5. 5. The solvent-free preparation method of the dynamic cross-linked epoxy resin according to claim 1, wherein the blocked isocyanate is selected from one or two or more of blocked-toluene diisocyanate, blocked-isophorone diisocyanate, blocked-diphenylmethane diisocyanate, blocked-hexamethylene diisocyanate, blocked-dicyclohexylmethane-4, 4' -diisocyanate and blocked-tetramethyl-m-xylylene diisocyanate, and the blocked isocyanate is formed by mixing the two or more of them in any proportion.
6. 6. The solvent-free preparation method of the dynamic cross-linked epoxy resin according to claim 1, wherein the epoxy resin monomer is formed by mixing one or two or more of bisphenol A diglycidyl ether, 1, 4-bis (ethylene oxide-2-ylmethoxy) benzene and resorcinol diglycidyl ether in any proportion.
7. 7. The solvent-free preparation method of the dynamic cross-linked epoxy resin according to claim 1, wherein the solvent-free mixing temperature is 80-100 ℃ for 10-15 min.
8. 8. The method for recycling the dynamic cross-linked epoxy resin is characterized by comprising the following steps of: Mixing the dynamic cross-linked epoxy resin, the diamine compound and an organic solvent, carrying out degradation reaction under the heating condition to obtain degradation liquid, adding the epoxy resin monomer into the degradation liquid, and curing to obtain the recovered epoxy resin.
9. 9. The method for recycling the dynamic cross-linked epoxy resin according to claim 8, wherein the heating condition is 150-180 ℃ and the reaction time is 6-8 hours.

Description

Solvent-free preparation method and recovery method of dynamic cross-linked epoxy resin Technical Field The application relates to the technical field of high polymer materials, in particular to a solvent-free preparation method and a recovery method of dynamic cross-linked epoxy resin. Background The epoxy resin is used as a thermosetting polymer with a highly crosslinked three-dimensional network structure, has excellent mechanical property, chemical stability and water resistance, and is widely applied to high-end fields such as wind power blades, electronic packaging, aerospace and the like. However, this stable, permanently crosslinked structure, while imparting excellent properties to the material, also makes it difficult to repair, remodel and recycle after service failure. The traditional landfill or incineration treatment mode not only causes resource waste, but also brings severe environmental pressure, which is contrary to the current concept of green sustainable development. To solve this problem, researchers have successfully developed dynamically crosslinked epoxy resins by introducing dynamic covalent bonds into the polymer network. Under specific external stimulus, the cross-linking points of the materials can be reversibly broken and recombined, so that the materials show the reworkability, self-repairing property and degradable recycling property similar to thermoplastics. However, the key properties of the dynamic cross-linked epoxy resin such as mechanics, heat and the like are seriously lost after the dynamic cross-linked epoxy resin is subjected to a repairing or recycling process, so that the re-application requirement is difficult to meet, and the full life cycle application value of the dynamic cross-linked epoxy resin is greatly limited. In related researches in the prior art, like (CN 116003988A), although an epoxy resin based on an amido urea dynamic bond is provided, the raw materials are easy to obtain and the synthesis is simple and convenient, the scheme not only depends on a large amount of DMF solvents in the preparation process and brings about environmental and safety concerns, but also causes long preparation period and high energy consumption through stepwise reaction, and the mechanical property of the recycled resin can only be recovered to about 80% of the original value, so that the performance attenuation is remarkable. The other solvent-free preparation method (CN 117603434A) avoids the use of solvent and shortens the preparation period of resin by designing a specific oily hydrazide monomer, but the synthesis route of key monomers is complicated, the period is long, the cost is high, the industrialized popularization is not facilitated, the technology is not related to the performance of the recovered materials, and the pain point of the core industry, namely the recovery performance attenuation, cannot be overcome. Thus, there is a strong need in the art for a solution for a dynamically crosslinked epoxy resin that combines easy preparation with high performance closed loop circulation capabilities. The scheme not only requires easily available raw materials, simple and convenient process and environmental protection, but also can ensure that the key performance of the material is maintained or even improved after the material is recovered. Disclosure of Invention In order to solve the problems, the invention provides a solvent-free preparation method and a recovery method of dynamic cross-linked epoxy resin. The novel oily hydrazide monomer with easily available raw materials and simple process is synthesized by design, and the epoxy resin based on the amido urea dynamic bond is directly prepared by mixing and solidifying the novel oily hydrazide monomer with components such as blocked isocyanate, epoxy resin and the like under the condition of not using any organic solvent by utilizing the novel oily hydrazide monomer. The core innovation point of the method is that the method not only realizes the green and high-efficiency of the preparation process, but also is more critical that the closed-loop recovery of the resin is successfully realized through a specific degradation-resolidification recovery process, and the mechanical and thermal properties of the recovered resin are not attenuated, but are obviously superior to those of the original resin, so that the technical bottleneck that the performance of the recovered dynamic crosslinked material is inevitably reduced is broken through. The invention provides a solvent-free preparation method of dynamic cross-linked epoxy resin, which is characterized by comprising the following steps of carrying out solvent-free mixing on oily hydrazide monomer, modified amine curing agent, blocked isocyanate and epoxy resin monomer to form a uniform mixture, defoaming, injection molding and curing to obtain the dynamic cross-linked epoxy resin, wherein the oily hydrazide monomer is prepared by reacting diamine compound with