CN-118852586-B - Preparation method of recyclable and easily-repairable epoxy resin, and product and recycling process thereof

Abstract

The invention discloses a preparation method of recoverable and easily-repairable epoxy resin, which is prepared by solidifying epoxy resin containing a borate structure or mixed resin consisting of epoxy resin containing a borate structure and conventional epoxy resin, wherein the structural formula of the epoxy resin containing the borate structure is shown as the following formula (I), R is one or more selected from the following formulas (II-1), (II-2) and (II-3), the preparation method disclosed by the invention is applicable to the conventional epoxy resin in the field, has universality, and the prepared product has recoverable and repairable properties and high strength.

Inventors

• ZHENG JIEYUAN
• WANG WENJUN
• YU ZONGGUI
• FAN HONG
• SHI SHENGBIN
• WANG DELIANG
• LIU PINGWEI

Assignees

• 浙江大学衢州研究院

Dates

Publication Date

20260508

Application Date

20240702

Claims (8)

1. 1. The preparation method of the recoverable and easily-repairable epoxy resin is characterized in that the recoverable and easily-repairable epoxy resin is prepared by solidifying epoxy resin containing a borate structure or mixed resin consisting of epoxy resin containing a borate structure and conventional epoxy resin; the structural formula of the epoxy resin containing the borate structure is shown as the following formula (I): (I); Wherein R is selected from one or more of the following formulas (II-1), (II-2) and (II-3); (II-1) (II-2) (II-3); the preparation method of the epoxy resin containing the borate structure specifically comprises the following steps: step 1, uniformly mixing 1-thioglycerol, an epoxy monomer containing unsaturated double bonds, a photoinitiator and a solvent I, and performing mercapto-alkene click chemical reaction; the epoxy monomer containing unsaturated double bonds is selected from one or more of eugenol glycidyl ether, allyl glycidyl ether and 1, 2-epoxy-4-vinylcyclohexane; step 2, adding 1,4 phenyldiboronic acid, a drying agent and a solvent II into a reactor, and obtaining the epoxy resin containing the boric acid ester structure after dehydration condensation reaction; The conventional epoxy resin is selected from one or more of aromatic epoxy resin, aliphatic epoxy resin and alicyclic epoxy resin.
2. 2. The method for preparing the recyclable and repairable epoxy resin as set forth in claim 1, wherein in step 1: The feeding mole ratio of the 1-thioglycerol to the epoxy monomer containing unsaturated double bonds is (0.95-1.05): 1; The ratio of the photoinitiator is 0.3-2.0 wt% based on the total mass of the 1-thioglycerol and the epoxy monomer containing unsaturated double bonds; The solvent I is one or more selected from methanol, tetrahydrofuran, toluene and acetone; the mass ratio of the solvent I to the total mass of the 1-thioglycerol and the epoxy monomer containing unsaturated double bonds is (0.5-10): 1.
3. 3. The method for preparing the recyclable and easily repairable epoxy resin according to claim 1, wherein in the step 1, the mercapto-alkene click chemical reaction is performed under ultraviolet irradiation, the reaction temperature is 10-50 ℃, and the reaction time is 1-5 h.
4. 4. The method for preparing the recyclable and repairable epoxy resin as set forth in claim 1, wherein in step 2: the feeding mole number of the 1, 4-phenyldiboronic acid is (48-52) percent of the mole number of the 1-thioglycerol in the step 1; the drying agent is one or more selected from anhydrous sodium sulfate, anhydrous magnesium sulfate and molecular sieves; The mass of the drying agent is (50-150) weight percent of the sum of the mass of the 1-thioglycerol, the unsaturated double bond-containing epoxy monomer and the mass of the 1, 4-phenyldiboronic acid; the solvent II is one or more selected from methanol, tetrahydrofuran, toluene and acetone; The mass ratio of the solvent II to the total mass of the 1-thioglycerol, the epoxy monomer containing unsaturated double bonds and the 1, 4-phenyldiboronic acid is (2-10): 1.
5. 5. The method for preparing the recyclable and repairable epoxy resin according to claim 1, wherein in the step 2, the dehydration condensation reaction is performed at a temperature of 10-50 ℃ for 12-48 hours.
6. 6. The method for preparing a recoverable and easily repairable epoxy resin according to claim 1, wherein a curing agent is further added into the raw materials.
7. 7. A recyclable, easily repairable epoxy resin prepared according to the method of any one of claims 1-6.
8. 8. The process for recycling the recyclable and easily-repairable epoxy resin according to claim 7, wherein the recyclable and easily-repairable epoxy resin is subjected to heating and molding, the temperature is 160-200 ℃, the pressure is 2-10 Mpa, and the time is less than or equal to 240 min.

Description

Preparation method of recyclable and easily-repairable epoxy resin, and product and recycling process thereof Technical Field The invention relates to the technical field of epoxy resin modification, in particular to a preparation method of recyclable and easily-repairable epoxy resin, a product and a recycling process thereof. Background Epoxy resins, which are one of three traditional thermosetting resins (epoxy, phenolic and unsaturated polyesters), have good mechanical and adhesive properties and are widely used in various industries such as paints, adhesives, electronic packaging, engineering plastics, composites, and the like. Because epoxy resin is thermosetting resin, a permanent cross-linked network structure is formed after curing is completed, so that excellent thermal stability and mechanical properties are brought, but the problems of difficult repeated processing and recycling are also caused, and along with iteration of products and reaching the service life, a large amount of epoxy resin faces treatment. Therefore, the environment-friendly and efficient recycling of the epoxy resin is realized, and the method is a necessary development trend of the epoxy resin industry. In 2011, the Leibler group found that a cured product obtained by adding an alkali metal salt to a carboxylic acid-curable epoxy resin exhibits thermosetting polymer properties at ordinary temperature, but a significant stress relaxation phenomenon occurs at high temperature. Further studies have found that the ester linkages in the crosslinked network are in dynamic exchange equilibrium, and Leibler teaches that such thermoset polymers containing reversible dynamic linkages are designated as "vitrimer" which Zhang Xi academy translates into "glass-like polymers". Based on this concept, many dynamic covalent bonds such as C-C bonds (Diels-Alder reaction), disulfide bonds, ester bonds, borate bonds, siloxane bonds, etc. have been found to induce topological network rearrangements at the molecular level under appropriate conditions, such as under the action of light, heat, even after polymer crosslinking, to achieve structural tuning or reorganization, thereby imparting self-healing, weldability, reworkability, and recyclability properties. The boric acid ester bond can realize bond exchange at a lower temperature without a catalyst, so that the boric acid ester bond is introduced into the epoxy resin to realize the efficient recovery of the epoxy resin. The resin is prepared from epoxy resin, a curing agent and an accelerator through a curing reaction, wherein the curing agent is a modified polyamine curing agent bridged by dynamic boric acid ester, and is prepared by reacting an organic amine molecule A1 with a phenylboronic acid group at one end with a polybasic glycol molecule B1 or reacting an organic amine molecule A2 with a single glycol group at one end with a polybasic phenylboronic acid molecule B2. The resin prepared by the method can realize better recovery and repair performance under a certain heating condition, but according to the records, the recovery time is at least 6 hours. More importantly, the processing conditions and application range of the epoxy resin are limited by the specific curing agent adopted by the technical scheme. Disclosure of Invention Aiming at the defects of the prior art, the invention discloses a preparation method of recoverable and easily-repairable epoxy resin, which is applicable to the conventional epoxy resin types in the field, has universality, and the prepared product has the advantages of recoverability and repairability and high strength. The specific technical scheme is as follows: The preparation method of recoverable and easily-repaired epoxy resin comprises the steps of preparing the recoverable and easily-repaired epoxy resin by using epoxy resin containing a borate structure or using mixed resin consisting of epoxy resin containing a borate structure and conventional epoxy resin after curing; the structural formula of the epoxy resin containing the borate structure is shown as the following formula (I): Wherein R is selected from one or more of the following formulas (II-1), (II-2) and (II-3); The epoxy resin containing the borate structure disclosed by the invention is novel in structure, the end group of the epoxy resin is eugenol glycidyl ether, allyl glycidyl ether or 1, 2-epoxy-4-vinylcyclohexane, the epoxy resin is in a liquid state at normal temperature, has excellent compatibility with various types of epoxy resins, can be cured independently or is mixed with a certain proportion of various types of conventional epoxy resins and then cured, the prepared epoxy resin cured product has excellent transparency, the tensile strength of the epoxy resin cured product is obviously improved, and the cured epoxy resin can realize the characteristics of damage repair and recycling under certain conditions. The preparation method of the epoxy resin containing the borate stru