阅读说明：本技术 一种植物油基柔性胺固化剂及其制备方法和植物油基韧性环氧树脂 (Vegetable oil-based flexible amine curing agent, preparation method thereof and vegetable oil-based tough epoxy resin ) 是由 林宇腾 施小妹 吴金彪 于 2020-07-16 设计创作，主要内容包括：本发明提供一种基于环氧大豆油和腰果酚的植物油基柔性胺固化剂及其制备方法和植物油基韧性环氧树脂,该固化剂通过在促进剂的存在下,使式I所示化合物和环氧大豆油发生反应制得,式I所示化合物的结构式为：<Image he="198" wi="700" file="DDA0002587340300000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>本发明通过对环氧树脂固化剂进行分子结构设计,在分子结构中引入柔性的长链大分子大豆油链段和柔性腰果酚链段,得到增韧改性的植物油基柔性胺固化剂,增加环氧树脂分子的柔性链段,达到增韧目的,改善环氧树脂的柔韧性。且环氧大豆油来源于大豆油,腰果酚来源于腰果壳油,均为可再生原料。(The invention provides a vegetable oil-based flexible amine curing agent based on epoxidized soybean oil and cardanol, a preparation method thereof and vegetable oil-based tough epoxy resin, wherein the curing agent is prepared by reacting a compound shown in a formula I with the epoxidized soybean oil in the presence of an accelerant, and the structural formula of the compound shown in the formula I is as follows: according to the invention, the epoxy resin curing agent is subjected to molecular structure design, and a flexible long-chain macromolecular soybean oil chain segment and a flexible cardanol chain segment are introduced into a molecular structure to obtain the toughening modified plant oil-based flexible amine curing agent, so that the flexible chain segment of an epoxy resin molecule is increased, the toughening purpose is achieved, and the flexibility of the epoxy resin is improved.The epoxidized soybean oil is derived from soybean oil, the cardanol is derived from cashew nut shell oil, and the epoxidized soybean oil and the cardanol are renewable raw materials.)

1. The preparation method of the plant oil-based flexible amine curing agent is characterized by comprising the step of reacting a compound shown in a formula I with epoxy soybean oil in the presence of an accelerator to prepare the plant oil-based flexible amine curing agent, wherein the compound shown in the formula I has a structural formula:

in the formula I, the compound has the following structure,

R₁is-CH₂-CH₂-、-CH₂-CH₂-NH-CH₂-CH₂-、-CH₂-CH₂-NH-CH₂-CH₂-NH-CH₂-CH₂-、-CH₂-CH₂-NH-CH₂-CH₂-NH-CH₂-CH₂-NH-CH₂-CH₂-, phenyl group,

n is 2 or 3.

2. The method of preparing the vegetable oil-based flexible amine curing agent of claim 1, wherein: the accelerant is one or more of triphenylphosphine, tetrabutylammonium bromide, benzyltrimethylammonium chloride, N-dimethylbenzylamine, methyltriphenylphosphonium bromide and 2,4, 6-tris (dimethylaminomethyl) phenol.

3. The method of preparing the vegetable oil-based flexible amine curing agent of claim 1, wherein: the reaction is carried out at 60-120 ℃, and the reaction time is 5-8 hours.

4. The method of preparing the vegetable oil-based flexible amine curing agent of claim 1, wherein: the compound shown in the formula I and epoxidized soybean oil are mixed in a molar ratio of active hydrogen equivalent to epoxy equivalent of 2-10: 1, feeding, wherein the mass ratio of the accelerator to the epoxidized soybean oil is (0.01-0.02): 1.

5. the method of preparing the vegetable oil-based flexible amine curing agent of claim 1, wherein the reaction is carried out as follows: and (2) adding the intermediate prepared in the step (1) into a reaction kettle, heating to 60-120 ℃, adding the epoxidized soybean oil and the accelerator dropwise or in an equivalent manner for 2-8 times, and reacting for 5-8 hours.

6. The preparation method of the vegetable oil-based flexible amine curing agent as claimed in claim 1, wherein the compound represented by the formula I is prepared by reacting cardanol, diamine and formaldehyde, wherein the cardanol has a structural formula as follows:n is 2 or 3.

7. The method of preparing the vegetable oil-based flexible amine curing agent of claim 6, wherein: the diamine is one or more of ethylenediamine, diethylenetriamine, triethylene tetramine, tetraethylene pentamine, m-phenylenediamine, m-xylylenediamine and isophorone diamine.

8. The method for preparing the vegetable oil-based flexible amine curing agent as claimed in claim 6, wherein the compound represented by the formula I is prepared by: under the protection of inert gas, mixing cardanol and diamine, reacting for 1-2 hours at 60-120 ℃, then adding formaldehyde, and reacting for 3-6 hours at 80-140 ℃; the charging molar ratio of the cardanol, the diamine and the formaldehyde is 1: 2-10: 1.5 to 2.5.

9. The method of preparing the vegetable oil-based flexible amine curing agent of claim 6, wherein: the preparation method of the compound shown in the formula I also comprises the step of carrying out post-treatment on the reaction liquid after the reaction is finished, wherein the post-treatment is vacuum-pumping to remove moisture and unreacted diamine.

10. The plant-based tough epoxy resin is prepared by mixing a curing agent and epoxy resin and then curing and molding, and is characterized in that: the curing agent is the plant oil-based flexible amine curing agent prepared by the preparation method of any one of claims 1 to 9.

Technical Field

The invention belongs to the technical field of epoxy curing agent preparation, and particularly relates to a vegetable oil-based flexible amine curing agent, a preparation method thereof and vegetable oil-based tough epoxy resin.

Background

The traditional epoxy resin has high brittleness, is limited in application in the application fields of plastic bonding and electronic encapsulation, and can expand the application range of the epoxy resin by toughening design of the molecular structure of the epoxy resin.

At present, two ways of matrix resin toughening and flexible curing agent use are mainly adopted for epoxy resin toughening:

matrix resin toughening is mainly realized by introducing a tough molecular chain to form a phase separation structure so as to increase the toughness of the whole material.

The flexible curing agent is used for introducing long chains and ether bonds to improve the toughness of the cured material, and the curing characteristic and the cured performance of the epoxy resin can be adjusted by the flexible curing agent, so that the modification has certain controllability.

At present, the flexible curing agent such as an amine curing agent modified by epoxidized soybean oil needs an intermediate medium solvent (such as alcohols, benzenes, ketones and the like) in the synthesis process, and has the advantages of low environmental protection, higher safety required by equipment, large energy consumption and low production efficiency.

For example, chinese patent CN201410325963.9 discloses a method for preparing a soybean oil-based epoxy resin curing agent, which comprises adding solvent-diluted epoxidized soybean oil dropwise into xylylenediamine under the protection of nitrogen, recovering the solvent under reduced pressure, and cooling to room temperature to obtain the soybean oil-based epoxy resin curing agent. In the synthesis process, ethyl acetate, acetone, butanone, cyclohexane or normal hexane is used as a solvent for diluting epoxidized soybean oil, and the operation of recovering the solvent under reduced pressure is carried out after the curing agent is synthesized, so that the hidden danger of partial solvent residue cannot be eliminated, and the material performance after the resin is mixed is further influenced. Meanwhile, the pressure reduction operation reduces the safety of equipment and increases energy consumption. Solvent recovery in turn has prompted the need for devices and accessories connected to the equipment to meet solvent resistance requirements.

Disclosure of Invention

The invention aims to solve the technical problem of overcoming the defects of the existing epoxy soybean oil modified amine curing agent and provides a preparation method of an improved vegetable oil-based flexible amine curing agent.

The second purpose of the invention is to provide the vegetable oil-based tough epoxy resin.

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of a vegetable oil-based flexible amine curing agent comprises the step of reacting a compound shown in a formula I with epoxy soybean oil in the presence of an accelerator to prepare the vegetable oil-based flexible amine curing agent, wherein the compound shown in the formula I has a structural formula:

in the formula I, the compound has the following structure,

R₁is-CH₂-CH₂-、-CH₂-CH₂-NH-CH₂-CH₂-、-CH₂-CH₂-NH-CH₂-CH₂-NH-CH₂-CH₂-、-CH₂-CH₂-NH-CH₂-CH₂-NH-CH₂-CH₂-NH-CH₂-CH₂-, phenyl group,n is 2 or 3.

In the invention, the compound shown in the formula I and the epoxidized soybean oil react as follows:

wherein R is₂Is composed of

According to some embodiments of the invention, the promoter is one or more of triphenylphosphine, tetrabutylammonium bromide, benzyltrimethylammonium chloride, N-dimethylbenzylamine, methyltriphenylphosphonium bromide, 2,4, 6-tris (dimethylaminomethyl) phenol.

According to some embodiments of the invention, the reaction is carried out at 60 to 120 ℃ for 5 to 8 hours.

Further, the reaction is specifically carried out as follows: adding the compound shown in the formula I into a reaction kettle, heating to 60-120 ℃, adding the epoxidized soybean oil and the accelerator dropwise or in an equivalent manner for 2-8 times, and reacting for 5-8 hours.

According to some embodiments of the invention, the compound of formula I and epoxidized soybean oil are present in a molar ratio of active hydrogen equivalents to epoxy equivalents of from 2 to 10: 1, feeding, wherein the mass ratio of the accelerator to the epoxidized soybean oil is (0.01-0.02): 1.

the active hydrogen equivalent is calculated by the following method: the total amine was determined by acid-base titration, and the primary and secondary amine values were measured by the 2-ethylhexanal-carbon disulfide method, and the active hydrogen equivalent was converted.

According to some embodiments of the invention, the compound of formula I is prepared by reacting cardanol, diamine and formaldehyde, wherein the cardanol has the following structural formula:

n is 2 or 3.

In the invention, the cardanol, diamine and formaldehyde react as follows:

further, the diamine is any one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, m-phenylenediamine, m-xylylenediamine and isophorone diamine.

Further, the preparation method of the compound shown in the formula I comprises the following steps: under the protection of inert gas, mixing cardanol and diamine, reacting for 1-2 hours at 60-120 ℃, then adding formaldehyde, and reacting for 3-6 hours at 80-140 ℃.

Further, the preparation method of the compound shown in the formula I also comprises a step of carrying out post-treatment on the reaction liquid after the reaction is finished, wherein the post-treatment is vacuum-pumping to remove moisture and unreacted diamine.

Further, the cardanol, diamine and formaldehyde are fed in a molar ratio of 1: 2-10: 1.5-2.5, preferably 1: 2-10: 2.

the other technical scheme adopted by the invention is as follows: the plant-based tough epoxy resin is prepared by mixing a curing agent and epoxy resin and then curing and molding, wherein the curing agent is the plant-oil-based flexible amine curing agent prepared by the preparation method.

Due to the implementation of the scheme, compared with the prior art, the invention has the following advantages:

according to the invention, the epoxy resin curing agent is subjected to molecular structure design, and a flexible long-chain macromolecular soybean oil chain segment and a flexible cardanol chain segment are introduced into a molecular structure to obtain the toughening modified plant oil-based flexible amine curing agent, so that the flexible chain segment of an epoxy resin molecule is increased, the toughening purpose is achieved, and the flexibility of the epoxy resin is improved. The epoxidized soybean oil is derived from soybean oil, the cardanol is derived from cashew nut shell oil, and the epoxidized soybean oil and the cardanol are renewable raw materials.

The preparation method of the vegetable oil-based flexible amine curing agent disclosed by the invention has the advantages that the vegetable oil-based flexible amine curing agent is prepared by reacting the compound shown in the formula I with the epoxy soybean oil under the action of the accelerator under the condition of no solvent, no solvent is involved in the reaction, the equipment requirement is reduced, and the hidden danger of solvent residue is eliminated.

Detailed Description

The invention is further illustrated by the following specific examples.