阅读说明：本技术 一种基于巯基-烯点击反应的丁香酚基环氧树脂固化剂、制备方法及应用 (Eugenol-based epoxy resin curing agent based on mercapto-alkene click reaction, preparation method and application ) 是由 张跃宏 翟梦姣 吕斌 王田田 张雷 刘晨阳 于 2019-10-11 设计创作，主要内容包括：本发明提供一种环氧树脂用生物质基固化剂的制备方法,所述固化剂为丁香酚基环氧树脂用二元胺类固化剂。本发明以天然可再生的丁香酚为主要原料,通过“烯丙基溴取代反应”和“巯基-烯点击反应”两步法,制备得到一种产率高、纯度高的丁香酚基二元胺。本发明设计的丁香酚基二元胺可以作为环氧树脂的固化剂,这种固化剂具有制备工艺简单、反应条件温和、低毒环保、环境友好等特性,符合新型绿色环保型固化剂的开发要求,有效改善了环氧树脂脆性高、抗冲击性差的问题。(The invention provides a preparation method of a biomass-based curing agent for epoxy resin, wherein the curing agent is a diamine curing agent for eugenol-based epoxy resin. The eugenol diamine with high yield and high purity is prepared by taking natural reproducible eugenol as a main raw material through a two-step method of allyl bromide substitution reaction and mercapto-alkene click reaction. The eugenol diamine designed by the invention can be used as a curing agent of epoxy resin, has the characteristics of simple preparation process, mild reaction conditions, low toxicity, environmental protection and the like, meets the development requirements of novel green environment-friendly curing agents, and effectively solves the problems of high brittleness and poor impact resistance of epoxy resin.)

1. The eugenol diamine curing agent for the epoxy resin is characterized by having the following structural formula:

（Ⅰ）。

2. the method for preparing the eugenol-based diamine curing agent for epoxy resin as claimed in claim 1, comprising the steps of:

two alkenyl groups in the 4-allyl-1- (allyloxy) -2-methoxybenzene AEG respectively react with sulfydryl groups in two cysteamine hydrochlorides, the pH value is adjusted to be alkaline, and the eugenol diamine curing agent is obtained through purification.

3. The method for preparing eugenol-based diamine curing agent for epoxy resin as claimed in claim 2, wherein the reaction is a click chemistry synthesis method of mercapto group and alkenyl group under ultraviolet light irradiation.

4. The method for preparing eugenol-based diamine curing agent for epoxy resin as claimed in claim 3, wherein the reaction comprises reacting excess cysteamine hydrochloride with 4-allyl-1- (allyloxy) -2-methoxybenzene AEG in a suitable organic solvent, and using 2, 2-dimethoxy-2-phenylacetophenone DMPA as a photoinitiator; the reaction system is irradiated by an ultraviolet lamp of 50 mw for 0.5 to 4 hours while stirring.

5. The method for preparing the eugenol-based diamine curing agent for epoxy resin as claimed in claim 3, wherein the amount of each component is, by mass: 50 parts of 4-allyl-1- (allyloxy) -2-methoxybenzene AEG, 300 parts of cysteamine hydrochloride and 2.5-5 parts of 2, 2-dimethoxy-2-phenylacetophenone DMPA.

6. The method for preparing eugenol-based diamine curing agent for epoxy resin as claimed in claim 2, wherein a proper amount of methanol is used as solvent to make cysteamine hydrochloride, 4-allyl-1- (allyloxy) -2-methoxybenzene AEG, 2-dimethoxy-2-phenylacetophenone DMPA to perform click chemistry reaction in methanol under the induction of ultraviolet light; after the reaction is finished, adjusting the pH value of the system to 10-10.5, and removing methanol by reduced pressure distillation; extracting and washing to neutrality, and finally drying, filtering and decompressing and rotary steaming to obtain the target product eugenyl diamine curing agent.

7. The method for preparing eugenol-based diamine curing agent for epoxy resin according to claim 2, wherein the 4-allyl-1- (allyloxy) -2-methoxybenzene AEG is obtained by a method comprising the following steps: uniformly mixing 100 parts of eugenol, 600-700 parts of organic solvent and 25-35 parts of alkaline substance, and heating to 65-80 ℃ while stirring for reaction for 10-30 min; then slowly dripping 110-150 parts of allyl bromide, and reacting for 4-12 h at the temperature; after the reaction is finished, cooling to room temperature, and respectively extracting and washing by using dichloromethane and water; finally, decompressing and rotary-steaming to remove dichloromethane, and drying and removing water to obtain an intermediate product 4-allyl-1- (allyloxy) -2-methoxybenzene AEG; the organic solvent is one or more of acetone, ethanol, ether and chloroform; the alkaline substance is sodium hydroxide, potassium carbonate or calcium oxide.

8. The use of the eugenol-based diamine curing agent for epoxy resin as set forth in claim 1 in an epoxy resin system.

9. The use of the eugenol-based diamine curing agent for epoxy resin as claimed in claim 8 in an epoxy resin system, comprising the steps of:

1) uniformly mixing 100 parts of epoxy resin and 20-80 parts of eugenol diamine curing agent, pouring the mixture into a self-made mold for molding, heating the mixture to 80-90 ℃ for curing for 1-3h, and curing the mixture at 100-120 ℃ for 2-4h to obtain a pre-cured product;

2) curing the pre-cured product at the temperature of 160-190 ℃ for 1-3h to obtain the cured epoxy resin.

10. The use of the eugenol-based diamine curing agent for epoxy resin as claimed in claim 9, wherein the epoxy resin is one or more of bisphenol a epoxy resin E51, bisphenol a epoxy resin E44 and novolac epoxy resin F44.

Technical Field

The invention belongs to the technical field of epoxy resin thermosetting high polymer materials, and particularly relates to a preparation method of a eugenol diamine curing agent and application of the eugenol diamine curing agent in epoxy resin.

Background

Epoxy resin is the most common thermosetting polymer material, and is widely applied to the fields of traffic, machinery, petrochemical industry, buildings and the like by virtue of the characteristics of excellent dimensional stability, chemical corrosion resistance, outstanding thermal stability, mechanical property and the like, so that great convenience is brought to the production and the life of people. The epoxy resin has a thermoplastic linear structure, and can be crosslinked to form an insoluble and infusible three-dimensional network structure after a proper curing agent is added, so that the material is endowed with excellent performance. Among them, amine-based curing agents are an important curing agent for epoxy resins.

At present, although many researches and patents are made on amine curing agents for epoxy resins, these curing agents (such as ethylenediamine, diethylenetriamine, triethylenetetramine, isophoronediamine, 1, 2-diaminocyclohexane, and the like) are mainly prepared from non-renewable petrochemical resources, and have the problems of complex and tedious preparation method, harsh process conditions, strong volatility, high toxicity, high reaction speed, and the like, and the cured products have the defects of poor toughness, low impact resistance, and the like, and are not beneficial to application and popularization. Researchers at home and abroad have less research on the biomass-based amine curing agent. Eugenol (Eugenol) is a biomass feedstock with a rigid structure. It has three main acquisition pathways: the first is obtained from plants such as clove, nutmeg and laurel; secondly, the lignin is obtained from hydrolysis or pyrolysis of lignin; thirdly, allyl chloride and guaiacol are used for synthesis. With the realization of industrial production of the method for obtaining the eugenol from the lignin, the cost of the eugenol can be further reduced, and the problem of high cost of preparing the epoxy resin curing agent by using the eugenol as the raw material is expected to be solved. In addition, the mercapto-alkene click reaction' is a green and environment-friendly novel synthesis method, the method has the advantages of simple operation, mild condition, quick reaction, insensitivity to water and oxygen, high yield, easy separation and purification of products and the like, and the development of the novel amine curing agent by using the method is expected to solve the problems of complex preparation method and harsh process conditions. Therefore, the method for preparing the novel amine curing agent for the epoxy resin by using the renewable resources as raw materials instead of petrochemical resources and adopting the mercapto-alkene click reaction has important significance for saving resources and protecting the environment.

Disclosure of Invention

The invention aims to provide a preparation method of an amine curing agent for epoxy resin by using biomass resource eugenol as a raw material. The curing agent for eugenol diamine epoxy resin prepared by mercapto-alkene click reaction has the advantages of low volatility, mild reaction conditions, simple preparation method and the like, and can improve the impact resistance of an epoxy resin curing system and endow materials with certain toughness after being compounded and cured with epoxy resin.

The structural formula of the curing agent for eugenol diamine epoxy resin is as follows:

（1）

the preparation method of the diamine curing agent for eugenol epoxy resin comprises the following steps:

the method comprises the following steps: uniformly mixing 100 parts of eugenol, 600-700 parts of organic solvent and 25-35 parts of alkaline substance, heating to 65-80 ℃ while stirring, reacting for 10-30 min, then slowly dropwise adding 150 parts of allyl bromide, reacting for 4-12 h at the temperature, cooling to room temperature after the reaction is finished, respectively extracting and washing with dichloromethane and water, finally carrying out reduced pressure rotary evaporation to remove dichloromethane, and drying to remove water to obtain an intermediate product AEG.

And step two, dissolving 50 parts of intermediate product AEG and 300 parts of 200-cysteamine hydrochloride in 1000 parts of 600-cysteamine methanol, irradiating for 0.5-4 h by using a 50 mw ultraviolet lamp while stirring in the presence of 2.5-5 parts of photoinitiator 2, 2-dimethoxy-2-phenylacetophenone (DMPA), filtering, adding a potassium carbonate solution to adjust the pH of the system to 10-10.5, distilling under reduced pressure to remove the methanol, extracting for three times by using dichloromethane, washing with saturated salt water to be neutral, drying, filtering and carrying out reduced pressure rotary evaporation to obtain the target product eugenol diamine curing agent.

The synthetic route is shown in FIG. 2.

The organic solvent in the step one is a common solvent, and preferably acetone, ethanol, diethyl ether and chloroform.

In the first step, the alkaline substance is sodium hydroxide, potassium carbonate or calcium oxide.

The concentration of the potassium carbonate solution in the first step is 10-40%.

The technological conditions for curing the epoxy resin by the curing agent prepared by the invention are as follows:

the method comprises the following steps: 100 parts of epoxy Bisphenol A diglycidyl ether DGEBA (Bisphenol A diglycidyl ether, C)₂₁H₂₄O₄340.41 g/mol) and 10-80 parts of eugenol diamine curing agent are evenly mixed and then poured into a self-made mould for molding, and the mixture is heated to 80-90 ℃ for curing for 1-3h and 100-120 ℃ for curing for 2-4h to obtain a pre-cured product.

Step two: curing the pre-cured product at the temperature of 160-190 ℃ for 1-3h to obtain the cured epoxy resin.

Compared with the prior art, the invention at least has the following beneficial effects:

(1) the raw material eugenol used in the invention has the characteristics of abundant resources, low cost, reproducibility, environmental protection and the like, and is beneficial to realizing industrial application.

(2) The invention provides a preparation method of an epoxy resin curing agent, which adopts a sulfydryl-alkene ultraviolet light click synthesis method in the preparation process, has the advantages of simple preparation process, mild reaction conditions, high yield, environmental friendliness and the like, and meets the development requirements of novel green and environment-friendly curing agents for epoxy resins.

(3) The eugenol-based curing agent provided by the invention has a linear flexible long-chain structure with a certain length, so that the impact toughness of the cured epoxy resin material is improved.

Drawings

FIG. 1 is a structural formula of eugenol diamine.

FIG. 2 is a synthetic route of eugenol diamine;

FIG. 3 is a nuclear magnetic spectrum of the product eugenol diamine;

FIG. 4 is a DSC spectrum of the cured epoxy resin DGEBA and eugenol diamine sample.

Detailed Description

The present invention is further described with reference to the following specific embodiments, and the technical solutions of the present invention are not limited to the specific embodiments listed below, and include any combination of the specific embodiments.