阅读说明：本技术 基于乙二胺四乙酸的支化聚酰胺环氧固化剂的合成方法 (Method for synthesizing branched polyamide epoxy curing agent based on ethylene diamine tetraacetic acid ) 是由 李保君 付绍祥 洪杰 于 2020-12-31 设计创作，主要内容包括：本发明涉及基于乙二胺四乙酸的支化聚酰胺环氧固化剂的合成方法,以脂肪胺、芳香胺、乙二胺四乙酸和二环己基碳二亚胺为原料,通过酰胺化反应制得小分子支化聚酰胺,本发明制备聚酰胺固化剂的方法简便,使用二环己基碳二亚胺催化酰胺化反应,大幅降低了反应温度,使得反应能够在常温常压下进行。(The invention relates to a synthesis method of a branched polyamide epoxy curing agent based on ethylene diamine tetraacetic acid, which takes aliphatic amine, aromatic amine, ethylene diamine tetraacetic acid and dicyclohexylcarbodiimide as raw materials to prepare micromolecule branched polyamide through amidation reaction.)

1. The synthesis method of the branched polyamide epoxy curing agent based on the ethylene diamine tetraacetic acid is characterized in that aliphatic amine, aromatic amine, ethylene diamine tetraacetic acid and dicyclohexylcarbodiimide are used as raw materials, and micromolecule branched polyamide is prepared through amidation reaction, wherein the reaction formula is as follows:

the specific synthesis steps are as follows:

firstly, weighing aliphatic amine, aromatic amine and dicyclohexylcarbodiimide, feeding the weighed aliphatic amine, aromatic amine and dicyclohexylcarbodiimide into a mixing reactor, controlling the temperature at 30-50 ℃, and stirring for 2 minutes under the protection of industrial nitrogen;

step two, adding ethylene diamine tetraacetic acid into the mixture evenly and for three times within 30 minutes, stirring the mixture to slowly dissolve the ethylene diamine tetraacetic acid into the system, and keeping the temperature for 3 hours to obtain viscous liquid;

thirdly, dripping the viscous liquid obtained after the reaction in the second step into cold tetrahydrofuran which accounts for 10 times of the mass of the viscous liquid, and filtering off waste residues to obtain filtrate;

fourthly, distilling the filtrate at 30 ℃ under reduced pressure to remove tetrahydrofuran, and obtaining the branched polyamide epoxy curing agent.

2. The method of synthesizing an ethylenediaminetetraacetic acid-based branched polyamide epoxy hardener, as claimed in claim 1, wherein the fatty amine: aromatic amine: ethylene diamine tetraacetic acid: the molar ratio of dicyclohexylcarbodiimide is 3.0-5.0:1.0-1.6:1.0: 4.2.

3. The method for synthesizing the ethylenediamine tetraacetic acid-based branched polyamide epoxy hardener as claimed in claim 1, wherein the aliphatic amine is ethylenediamine, hexamethylenediamine, diethylenetriamine or triethylenetetramine.

4. The method for synthesizing an ethylenediaminetetraacetic acid-based branched polyamide epoxy hardener as claimed in claim 1, wherein the aromatic amine is m-xylylenediamine, m-phenylenediamine or diaminodiphenylmethane.

Technical Field

The invention relates to the technical field of curing agent preparation, in particular to a method for synthesizing a branched polyamide epoxy curing agent based on ethylenediamine tetraacetic acid.

Background

The epoxy resin curing agent is an extremely important material in the technical field of epoxy resin application, and is also a key component for determining the process technology and characteristics of epoxy products. The development of the epoxy resin application technology is closely related to the structure, specification and quality of the curing agent, and the application of the curing agent to realize the ideal application effect of the epoxy resin is the main task of formula design.

The straight-chain polyamine is the simplest curing agent and the most diverse curing agent, and is characterized in that the curing agent can generally carry out curing reaction with epoxy resin at room temperature, but primary ammonia can react with carbon dioxide in air to generate carbonate, so that the coating application and the performance of a cured product are seriously influenced, and the large-area construction can be adversely influenced. In order to solve the above problems, polyamide curing agents have been developed. Polyamide curing agents, also known as low molecular weight polyamides or polyamidopolyamines, are generally prepared by reacting dimer acids such as linoleic acid with aliphatic polyamines to produce low molecular weight polyamide compounds. The addition amount of the polyamide curing agent is wide in allowable range, and the curing agent is almost non-toxic, nonvolatile and has little irritation to skin. The cured epoxy resin has balanced mechanical and electrical properties, excellent impact resistance and especially good cohesiveness. The epoxy resin cured material cured by the low molecular polyamide has better comprehensive performance, so the method is also a hot spot modification method of the polyamine curing agent.

The polycarboxylic acid raw materials for producing low molecular weight polyamide at home usually adopt vegetable oil fatty acid dimers, such as eleostearic acid dimer, linoleic acid dimer and the like, the polycarboxylic acid needs to react with poly primary amine at high temperature (300 ℃), and high-pressure environment is often needed during synthesis, so that the polycarboxylic acid has higher safety risk during actual production. In addition, although polyamide curing agents have a good toughening effect on epoxy cured products, there is still an increasing demand for applications in the field of high impact strength (e.g., coatings for automobiles, bridges, and steel frame structures). Therefore, the development of polyamide curing agents with simple production process and excellent impact resistance is a research hotspot in the academic and industrial fields at present.

The conventional vegetable oil fatty acid dimer has harsh synthesis conditions and needs high temperature and high pressure; the molecules of the conventional polyamide curing agent are in a linear chain structure, and the toughening effect on the epoxy cured product can be further improved.

Disclosure of Invention

Technical problem to be solved

In order to solve the problems in the prior art, the invention provides a method for synthesizing a branched polyamide epoxy curing agent based on ethylene diamine tetraacetic acid.

(II) technical scheme

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

the synthesis method of the branched polyamide epoxy curing agent based on the ethylene diamine tetraacetic acid takes aliphatic amine, aromatic amine, ethylene diamine tetraacetic acid and dicyclohexylcarbodiimide as raw materials, and prepares the micromolecule branched polyamide through amidation reaction, wherein the reaction formula is as follows:

the specific synthesis steps are as follows:

firstly, weighing aliphatic amine, aromatic amine and dicyclohexylcarbodiimide, feeding the weighed aliphatic amine, aromatic amine and dicyclohexylcarbodiimide into a mixing reactor, controlling the temperature at 30-50 ℃, and stirring for 2 minutes under the protection of industrial nitrogen;

step two, adding ethylene diamine tetraacetic acid into the mixture evenly and for three times within 30 minutes, stirring the mixture to slowly dissolve the ethylene diamine tetraacetic acid into the system, and keeping the temperature for 3 hours to obtain viscous liquid;

thirdly, dripping the viscous liquid obtained after the reaction in the second step into cold tetrahydrofuran which accounts for 10 times of the mass of the viscous liquid, and filtering off waste residues to obtain filtrate;

fourthly, distilling the filtrate at 30 ℃ under reduced pressure to remove tetrahydrofuran, and obtaining the branched polyamide epoxy curing agent.

Further, the fatty amine: aromatic amine: ethylene diamine tetraacetic acid: the molar ratio of dicyclohexylcarbodiimide is 3.0-5.0:1.0-1.6:1.0: 4.2.

Further, the aliphatic amine is ethylenediamine, hexamethylenediamine, diethylenetriamine or triethylenetetramine.

Further, the aromatic amine is m-xylylenediamine, m-phenylenediamine or diaminodiphenylmethane.

(III) advantageous effects

The invention has the beneficial effects that: 1. the method for preparing the polyamide curing agent is simple and convenient, and the Dicyclohexylcarbodiimide (DCC) is used for catalyzing amidation reaction, so that the reaction temperature is greatly reduced, and the reaction can be carried out at normal temperature and normal pressure.

2. The ethylene diamine tetraacetic acid is cheap, easily available, nontoxic and harmless four-functionality polybasic acid, and can be used for preparing a branched polyamide compound with polyamine.

3. The branched polyamide compound prepared by the invention overcomes the high toxicity of polyamine, and the amide and branched structure of the branched polyamide compound are beneficial to increasing the flexibility and the adhesiveness of cured epoxy resin, so that the branched polyamide compound has good comprehensive performance.

Detailed Description

For a better understanding of the present invention, reference will now be made in detail to the present invention by way of specific embodiments thereof.

The synthesis method of the branched polyamide epoxy curing agent based on the ethylene diamine tetraacetic acid takes aliphatic amine, aromatic amine, Ethylene Diamine Tetraacetic Acid (EDTA) and Dicyclohexylcarbodiimide (DCC) as raw materials, and prepares the micromolecule branched polyamide through amidation reaction, wherein the reaction formula is as follows:

the specific synthesis steps are as follows:

firstly, weighing aliphatic amine, aromatic amine and dicyclohexylcarbodiimide, feeding the weighed aliphatic amine, aromatic amine and dicyclohexylcarbodiimide into a mixing reactor, controlling the temperature at 30-50 ℃, and stirring for 2 minutes under the protection of industrial nitrogen;

step two, adding ethylene diamine tetraacetic acid into the mixture evenly and for three times within 30 minutes, stirring the mixture to slowly dissolve the ethylene diamine tetraacetic acid into the system, and keeping the temperature for 3 hours to obtain viscous liquid;

thirdly, dripping the viscous liquid obtained after the reaction in the second step into cold Tetrahydrofuran (THF) which accounts for 10 times of the mass of the viscous liquid, placing the viscous liquid in a refrigerator for one hour, and filtering off waste residues to obtain filtrate;

fourthly, distilling the filtrate at 30 ℃ under reduced pressure to remove tetrahydrofuran, and obtaining the branched polyamide epoxy curing agent.

Further, the fatty amine: aromatic amine: ethylenediaminetetraacetic acid (EDTA): the molar ratio of Dicyclohexylcarbodiimide (DCC) is 3.0-5.0:1.0-1.6:1.0: 4.2.

Further, the aliphatic amine is ethylenediamine, hexamethylenediamine, diethylenetriamine or triethylenetetramine.

Further, the aromatic amine is m-xylylenediamine, m-phenylenediamine or diaminodiphenylmethane.

Polyamides synthesized from conventional vegetable oil dimers are linear polymers; ethylene Diamine Tetraacetic Acid (EDTA) is a cheap, easily-obtained, nontoxic and harmless four-functionality polybasic acid, and can be reacted with diamine to prepare a branched polyamide compound; compared with linear polymers, the branched polymer has the characteristics of low viscosity, high functionality, good solubility, no chain entanglement and the like, and provides a new effective method for toughening and modifying the epoxy resin.

In addition, based on the principle of similar compatibility, the partial aromatic amine is introduced into the system, so that the compatibility of the curing agent component and the epoxy resin can be enhanced, and the hardness and the strength of a cured product can be improved.

Example 1

1. In a 200ml reaction flask, a stirrer, a thermometer, a charging port and a vent tube were installed. 29.20g of triethylene tetramine, 10.20g of m-xylylenediamine and 43.26g of dicyclohexyl carbodiimide are added and mixed, and the mixture is kept at 40 ℃ for 2 minutes under the protection of nitrogen;

2. slowly adding 14.60g of ethylenediamine tetraacetic acid through a feed inlet, and controlling the time to be 30 minutes;

3. reacting for 3 hours to obtain viscous liquid, taking out the viscous liquid, dripping the viscous liquid into 500ml of cold Tetrahydrofuran (THF), standing the viscous liquid in a refrigerator for 1 hour, and filtering out filter residues;

4. finally, the filtrate was distilled under reduced pressure at 30 ℃ to remove tetrahydrofuran, to obtain 45.24g of a yellow viscous liquid, i.e., a branched polyamide epoxy hardener, with a yield of 89.7% (using ethylenediaminetetraacetic acid as a substrate) and an amine value of 730 mgKOH/g.

The above description is only a preferred embodiment of the present invention, and all equivalent changes and modifications made in accordance with the claims of the present invention should be covered by the present invention.