阅读说明：本技术 一种聚酰亚胺的绿色制备方法 (Green preparation method of polyimide ) 是由 刘丽 苑成策 李达志 杜韫哲 黄玉东 于 2019-11-22 设计创作，主要内容包括：本发明公开了一种聚酰亚胺的绿色制备方法,属于高分子材料领域,具体方案如下：一种聚酰亚胺的绿色制备方法包括如下步骤：步骤一、单体与溶剂的除水处理；步骤二、有机溶剂体系中聚酰胺酸的合成；步骤三、聚酰胺酸与有机溶剂的分离；步骤四、聚酰胺酸的热亚胺化；步骤五、溶剂的回收再利用。本发明操作简便,产物与溶剂分离率高,溶剂回收率高,亚胺化工序节约能量,可以较为绿色环保的制备聚酰亚胺。(The invention discloses a green preparation method of polyimide, belonging to the field of high polymer materials, and the specific scheme is as follows: the green preparation method of the polyimide comprises the following steps: step one, water removal treatment of a monomer and a solvent; step two, synthesizing polyamic acid in an organic solvent system; step three, separating the polyamic acid from the organic solvent; step four, thermal imidization of polyamic acid; and step five, recycling the solvent. The method has the advantages of simple and convenient operation, high separation rate of the product and the solvent, high solvent recovery rate, energy saving in the imidization process and capability of preparing the polyimide in a green and environment-friendly way.)

1. A green preparation method of polyimide is characterized by comprising the following steps: the method comprises the following steps:

step one, water removal treatment of a monomer and a solvent, namely performing water removal treatment on a dianhydride monomer, a diamine monomer and an organic solvent;

step two, synthesis of polyamic acid in an organic solvent system: the dianhydride monomer and the diamine monomer are mixed according to a molar ratio of 0.95-1.05: dissolving the polyamide acid 1 in an organic solvent according to the proportion, wherein the mass concentration of the system is 8-18%, the reaction temperature is 10-35 ℃, and the reaction time is 1-12 h to obtain an organic solution of polyamide acid;

step three, separating polyamic acid from organic solvent: adding an ethanol aqueous solution with the ethanol volume fraction of 0-50% into the organic solution of the polyamic acid at the speed of 10-60 drops per minute until no precipitate is generated; filtering and separating the precipitate and the clear solution, washing the precipitate for 5-10 times by using deionized water, and drying the precipitate to obtain polyamide acid after separation;

step four, thermal imidization of polyamic acid: heating polyamide acid to 150-180 ℃ from room temperature in inert gas or air atmosphere, and preserving heat for 0.5-3 h; then heating to 190-210 ℃ and preserving the heat for 0.5-3 h; then heating to 230-300 ℃ and preserving the heat for 0.5-3 h; and finally, slowly cooling to room temperature to obtain the polyimide.

2. The green preparation method of polyimide according to claim 1, wherein: the method also comprises the following steps of recycling and reusing the solvent: and (3) heating the clear solution obtained in the third step to 75-120 ℃ gradually to evaporate the mixed water or ethanol water solution to obtain the organic solvent which can be used for the polyimide synthesis continuously.

3. The green preparation method of polyimide according to claim 1, wherein: in the first step, the dianhydride monomer is one or more of pyromellitic benzoic anhydride, 2,3, 3', 4' -diphenyl ether tetracarboxylic dianhydride, 3,3', 4' -benzophenone tetracarboxylic dianhydride, 4,4' -diphenyl ether dianhydride and 1,2,3, 4-cyclopentane tetracarboxylic dianhydride; the diamine monomer is one or more of 4,4 '-diaminodiphenyl ether, p-phenylenediamine, 3,3' -dimethyl-4, 4 '-diaminodicyclohexylmethane, 3,3' -methylene diphenylamine, 4,4 '-diaminobenzophenone and 4,4' -ethylene diphenylamine; the organic solvent is one or more of dimethylformamide, dimethylacetamide and dimethyl sulfoxide.

4. The green preparation method of polyimide according to claim 1, wherein: in the first step, a common oven or a vacuum oven is adopted to carry out dehydration treatment on the dianhydride monomer, the diamine monomer and the organic solvent, the drying temperature is 40-90 ℃, and the drying time is 2-12 hours.

5. The green preparation method of polyimide according to claim 1, wherein: in the third step, the temperature of the dried precipitate is 75-95 ℃ and the time is 3-6 h.

Technical Field

The invention relates to the field of high polymer materials, in particular to a preparation method of environment-friendly polyimide.

Background

Polyimide is one of engineering plastics, has more excellent mechanical properties, heat resistance, processability and recyclability compared with common thermosetting epoxy resin, and has been widely applied to high-end fields such as novel automobiles, aerospace, microelectronics, separation membranes and the like.

Polyimide was first reported in 1908, but was not really developed as a polymer material until 50 s, and in particular, DuPont applied for a large number of patents on polyimide since 60 s, and commercialized polyimide appeared gradually. At present, the synthesis method of polyimide is very mature, and the most common synthesis method is a two-step method, namely, firstly, dianhydride and diamine monomers are used in an aprotic polar organic solvent to synthesize polyamic acid, and then the polyamic acid is imidized to prepare the polyimide. Imidization is the most critical step in the synthesis of polyimide, and the common methods are thermal imidization and chemical imidization, wherein thermal imidization is the most common method because the method has a wide application range and high imidization degree.

The synthetic method of polyimide is very mature, and the problem is very obvious. That is, the use of aprotic polar organic solvent is usually dimethylformamide, dimethylacetamide and the like, and has strong toxicity and boiling point of over 150 ℃; the residue of the organic solvent also affects the determination of the temperature rising system of the thermal imidization, and causes energy waste. Therefore, it is required to develop a method for preparing polyimide having both product and solvent separation efficiency and solvent recyclability.

Disclosure of Invention

In order to overcome the limitation of the prior art and aim at recycling organic solvent and saving energy, the invention provides a green preparation method of polyimide, which has the advantages of simple and convenient operation, high separation rate of products and solvent, high solvent recovery rate, energy saving in imidization process and capability of preparing polyimide in a green and environment-friendly way.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a green preparation method of polyimide comprises the following steps:

step one, water removal treatment of a monomer and a solvent, namely performing water removal treatment on a dianhydride monomer, a diamine monomer and an organic solvent;

step two, synthesis of polyamic acid in an organic solvent system: the dianhydride monomer and the diamine monomer are mixed according to a molar ratio of 0.95-1.05: dissolving the polyamide acid 1 in an organic solvent according to the proportion, wherein the mass concentration of the system is 8-18%, the reaction temperature is 10-35 ℃, and the reaction time is 1-12 h to obtain an organic solution of polyamide acid;

step three, separating polyamic acid from organic solvent: adding an ethanol aqueous solution with the ethanol volume fraction of 0-50% into the organic solution of the polyamic acid at the speed of 10-60 drops per minute until no precipitate is generated; filtering and separating the precipitate and the clear solution, washing the precipitate for 5-10 times by using deionized water, and drying the precipitate to obtain polyamide acid after separation;

step four, thermal imidization of polyamic acid: heating polyamide acid to 150-180 ℃ from room temperature in inert gas or air atmosphere, and preserving heat for 0.5-3 h; then heating to 190-210 ℃ and preserving the heat for 0.5-3 h; then heating to 230-300 ℃ and preserving the heat for 0.5-3 h; and finally, slowly cooling to room temperature to obtain the polyimide.

Further, the method also comprises the following steps of recycling and reusing the solvent: and (3) heating the clear solution obtained in the third step to 75-120 ℃ gradually to evaporate the mixed water or ethanol water solution to obtain the organic solvent which can be used for the polyimide synthesis continuously.

Further, in the first step, the dianhydride monomer is one or more of pyromellitic benzoic anhydride, 2,3, 3', 4' -diphenyl ether tetracarboxylic dianhydride, 3,3', 4' -benzophenone tetracarboxylic dianhydride, 4,4' -diphenyl ether dianhydride, and 1,2,3, 4-cyclopentane tetracarboxylic dianhydride; the diamine monomer is one or more of 4,4 '-diaminodiphenyl ether, p-phenylenediamine, 3,3' -dimethyl-4, 4 '-diaminodicyclohexylmethane, 3,3' -methylene diphenylamine, 4,4 '-diaminobenzophenone and 4,4' -ethylene diphenylamine; the organic solvent is one or more of dimethylformamide, dimethylacetamide and dimethyl sulfoxide.

Further, in the first step, a common oven or a vacuum oven is adopted to carry out dewatering treatment on the dianhydride monomer, the diamine monomer and the organic solvent, the drying temperature is 40-90 ℃, and the drying time is 2-12 hours.

Further, in the third step, the temperature for drying the precipitate is 75-95 ℃ and the time is 3-6 h.

The invention has the following advantages:

the invention solves the problems of separation of the polyamic acid and the organic solvent and recycling of the organic solvent by using a simple and convenient method, provides a feasible green and environment-friendly polyimide synthesis method, and has important significance for green production of polyimide.

Detailed Description

The technical solutions of the present invention are further described below with reference to the following examples, but the present invention is not limited thereto, and any modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.