阅读说明：本技术 一种高固含量低粘度聚酰胺酸溶液的制备方法 (Preparation method of high-solid-content low-viscosity polyamic acid solution ) 是由 孙利滨 于 2020-09-30 设计创作，主要内容包括：本发明涉及一种高固含量低粘度聚酰胺酸溶液的制备方法,包括：将羧酸铵盐双子表面活性剂与极性非质子溶剂混合,搅拌,加入二胺单体,继续搅拌,加入部分二酐单体反应,再加入剩余二酐单体继续反应。该方法操作简单,工艺环保,有利于大批量制备,具有很好的产业化前景,制备得到的聚酰胺酸溶液固含量高且粘度低,具有优良的流涎、旋涂、涂布加工性,可应用于柔性显示用电路基板制造、电子器件封装等多个领域。(The invention relates to a preparation method of a high-solid-content low-viscosity polyamic acid solution, which comprises the following steps: mixing ammonium carboxylate gemini surfactant with polar aprotic solvent, stirring, adding diamine monomer, continuously stirring, adding part dianhydride monomer for reaction, and adding the rest dianhydride monomer for continuous reaction. The method is simple to operate, environment-friendly in process, beneficial to large-scale preparation, good in industrialization prospect, high in solid content and low in viscosity of the prepared polyamide solution, excellent in drooling, spin coating and coating processability, and capable of being applied to multiple fields of manufacturing of circuit substrates for flexible display, packaging of electronic devices and the like.)

1. A method for preparing a high-solid-content low-viscosity polyamic acid solution, comprising:

mixing an ammonium carboxylate gemini surfactant with a polar aprotic solvent, stirring, adding a diamine monomer, continuously stirring, adding a part of dianhydride monomer for reaction, and then adding the rest dianhydride monomer for continuous reaction to obtain a polyamide acid solution, wherein the molar concentration of the ammonium carboxylate gemini surfactant in the polar aprotic solvent is 0.0001-0.1 mol/L, the mol of the part of dianhydride monomer accounts for 80-100% of the total mol of the diamine monomer, and the molar ratio of the ammonium carboxylate gemini surfactant to the diamine monomer is 1: 24-1: 67.

2. The method of claim 1, wherein said ammonium carboxylate gemini surfactant has the formula: wherein R is CH₃(CH₂) n, n ═ 7, 9, 11, 13, 15, or 17.

3. The method of claim 1, wherein the polar aprotic solvent comprises one of N, N '-dimethylformamide, N' -dimethylacetamide, N-methyl-2-pyrrolidone, dimethylsulfoxide.

4. The method of claim 1, wherein the diamine monomer comprises one or more of p-phenylenediamine, 2,5 '-bis 4- (aminophenyl) pyrimidine, m-phenylenediamine, 4' -diaminodiphenyl ether, 3 '-diaminodiphenyl ether, 2- (4-aminophenyl) -5-aminobenzimidazole, and 3,4' -diaminodiphenyl ether; the total mass of the diamine monomer accounts for 8-17% of the total mass of the reaction system.

5. The method of claim 1, wherein the agitating is: stirring at 50-60 ℃ to dissolve the ammonium carboxylate gemini surfactant; the continuous stirring time is 2-4 h.

6. The method of claim 1, wherein the dianhydride monomer comprises one or more of pyromellitic dianhydride, 2,3,3',4' -biphenyltetracarboxylic dianhydride, 3,3',4,4' -biphenyltetracarboxylic dianhydride, hexafluoro dianhydride, 3,3',4,4' -benzophenone tetracarboxylic dianhydride, 3,3',4,4' -diphenyl ether tetracarboxylic dianhydride, 2,3,3',4' -diphenyl ether tetracarboxylic dianhydride; the total mole ratio of diamine monomer to dianhydride monomer was 1: 1.

7. The method of claim 1, wherein the reaction is: cooling to 10-40 ℃ and reacting for 6-12 h; the continuous reaction time is 2-18 h.

8. The method according to claim 1, wherein the mass fraction of polyamic acid in the polyamic acid solution is 16 to 35%; the viscosity of the polyamide acid solution is 2000-25000 cP.

9. A polyamic acid solution prepared according to the method of claim 1.

10. Use of the polyamic acid solution prepared according to the process of claim 1.

Technical Field

The invention belongs to the field of preparation of polyamic acid solution, and particularly relates to a preparation method of polyamic acid solution with high solid content and low viscosity.

Background

Polyimide (PI) is a high-performance polymer with a molecular chain containing an imide ring structure, and the high-performance polymer has the characteristics of excellent mechanical strength, dimensional temperature property, high temperature resistance, irradiation resistance, corrosion resistance, insulation and the like due to a highly conjugated molecular structure, and high-performance materials prepared from the Polyimide (PI) such as films, fibers, resins, coatings and the like are widely applied to high-tech fields such as flexible display, semiconductor packaging, photovoltaic energy, aerospace, military industry and the like. Polyimide films are the most widely and successfully used polyimide products, and have been the focus of attention in various countries, especially in recent years, the industries such as OLED and flexible electronic display have been in the wake, and the polyimide films have been researched recently. Polyimide which is usually used in the field of OLED has a highly conjugated chemical structure and is difficult to dissolve in a conventional organic solvent, so the polyimide film material is usually prepared by a two-step technical route, namely a precursor (polyamic acid) of polyimide is used for film preparation processing, and the polyamic acid is subjected to a ring-closing reaction through subsequent imidization treatment to obtain the polyimide film material. Currently, films such as the Kapton series film from Dupont, the apicai series film from Kaneka, and the U-pilex series film from Ube are produced by this technology route.

When the two-step processing is adopted, although polyamic acid has certain solubility in polar aprotic solvents, strong interaction between polymer molecular chains easily leads to rapid increase of solution viscosity when the solid content is higher, and even gelation occurs to lose the processability. Therefore, the preparation of the polyamic acid solution with high solid content and good fluidity is the key for preparing the high-performance polyimide film. From the structural analysis, strong hydrogen bonding interaction between molecular chains is an important cause of poor flow of the high-solid content polyamic acid solution. Based on the principle, Chinese patent CN201410023969.0 discloses that trimethyl silane with a certain mass is added when diamine and dianhydride are polymerized, so that hydrogen bonds among polyamic acid molecular chains are destroyed, and a polyamic acid solution with the solid content of 12-20% and the viscosity of 0.5-1.5 ten thousand centipoise is obtained. Chinese patent CN201410557628.1 discloses the addition of silicone based adhesion promoters to polyamic acid solutions, also resulting in high content of low viscosity polyamic acid solutions.

Besides silane micromolecules, the surfactant serving as an amphiphilic substance can also be effectively used for regulating and controlling the rheological property of the solution, and the surfactant usually has the characteristic of low Critical Micelle Concentration (CMC), and the property of the solution can be obviously changed by adding a trace amount of the surfactant, so that the surfactant has obvious advantages compared with a method for adding micromolecules, and for example, complex systems such as polyelectrolyte/surfactant, biological polysaccharide/surfactant and the like are widely applied in the fields of crude oil displacement, cosmetic rheological control, lubricants and the like.

Disclosure of Invention

The invention aims to solve the technical problem of providing a preparation method of a high-solid-content low-viscosity polyamic acid solution so as to overcome the defects of high viscosity and difficult processing of the high-solid-content polyamic acid solution in the prior art.

The invention provides a preparation method of a high-solid-content low-viscosity polyamic acid solution, which comprises the following steps:

mixing an ammonium carboxylate gemini surfactant with a polar aprotic solvent, stirring, adding a diamine monomer, continuously stirring to a homogeneous phase, adding a part of dianhydride monomer for reaction, and then adding the rest dianhydride monomer for continuous reaction to obtain a polyamide acid solution, wherein the molar concentration of the ammonium carboxylate gemini surfactant in the polar aprotic solvent is 0.0001-0.1 mol/L, the mol of the part of dianhydride monomer accounts for 80-100% of the total mol of the diamine monomer, and the molar ratio of the ammonium carboxylate gemini surfactant to the diamine monomer is 1: 24-1: 67.

The structural formula of the ammonium carboxylate gemini surfactant is as follows:

wherein R is CH₃(CH₂) n, n ═ 7, 9, 11, 13, 15, or 17.

The polar aprotic solvent comprises one of N, N '-dimethylformamide, N' -dimethylacetamide, N-methyl-2-pyrrolidone and dimethyl sulfoxide.

The diamine monomer comprises one or more of p-phenylenediamine, 2,5 '-di-4- (aminophenyl) pyrimidine, m-phenylenediamine, 4' -diaminodiphenyl ether, 3 '-diaminodiphenyl ether, 2- (4-aminophenyl) -5-aminobenzimidazole and 3,4' -diaminodiphenyl ether.

The total mass of the diamine monomer accounts for 8-17% of the total mass of the reaction system.

The stirring is as follows: stirring at 50-60 ℃ to dissolve the ammonium carboxylate gemini surfactant.

And the continuous stirring time is 2-4 h.

The dianhydride monomer comprises one or more of pyromellitic dianhydride, 2,3,3',4' -biphenyl tetracarboxylic dianhydride, 3,3',4,4' -biphenyl tetracarboxylic dianhydride, hexafluoro dianhydride, 3,3',4,4' -benzophenone tetracarboxylic dianhydride, 3,3',4,4' -diphenyl ether tetracarboxylic dianhydride and 2,3,3',4' -diphenyl ether tetracarboxylic dianhydride.

The molar ratio of the total moles of diamine monomer to the total moles of dianhydride monomer is 1: 1.

The reaction is as follows: cooling to 10-40 ℃ and reacting for 6-12 h.

The continuous reaction time is 2-18 h.

The mass fraction of the polyamide acid in the polyamide acid solution is 16-35%; the viscosity of the polyamide acid solution is 2000-25000 cP.

The invention also provides the polyamic acid solution prepared by the method.

The invention also provides application of the polyamic acid solution prepared by the method. For example, for the preparation of polyimide films.

The invention firstly introduces a novel ammonium carboxylate gemini surfactant into a polyamic acid synthesis system, and coats aromatic diamine by utilizing the hydrophobic core of micelle, thereby effectively controlling the degree of polycondensation reaction and obtaining the polyamic acid solution with high solid content and low viscosity.

Advantageous effects

(1) The added ammonium carboxylate gemini surfactant has low molar concentration, the molar quantity of diamine is equal to that of dianhydride, the prepared polyamide acid solution has high solid content and low viscosity, and the polyamide acid solution has excellent salivation, spin coating and coating processability and can be applied to a plurality of fields of manufacturing of circuit substrates for flexible display, packaging of electronic devices and the like. The prepared polyimide film has excellent mechanical property and heat resistance.

(2) The method is simple to operate, environment-friendly in process, beneficial to mass preparation and good in industrialization prospect.

Detailed Description

The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.

Primary reagents such as p-phenylenediamine, 2,5 '-bis 4- (aminophenyl) pyrimidine, m-phenylenediamine, 4,4' -diaminodiphenyl ether, 3,3 '-diaminodiphenyl ether, 2- (4-aminophenyl) -5-aminobenzimidazole, 3,4' -diaminodiphenyl ether, pyromellitic dianhydride, 2,3,3',4' -biphenyltetracarboxylic dianhydride, 3,3',4,4' -biphenyltetracarboxylic dianhydride, hexafluorodianhydride, 3,3',4,4' -benzophenonetetracarboxylic dianhydride, 3,3',4,4' -diphenylethertetracarboxylic dianhydride, 2,3,3',4' -diphenylethertetracarboxylic dianhydride, and ammonium carboxylate gemini surfactants are commercially available from commercial products or reagents, and are required to have a purity of 99% or more.

The strength test method is carried out according to the determination of tensile properties of plastics of national standard GB/T1040.3-2006.

Example 1

(1) In a 250mL three-neck flask, 150mL of N-methyl-2-pyrrolidone (the water content is less than 100ppm) and 1.568g of benzophenone carboxylic acid ammonium salt surfactant (0.002mol, the structure is shown as the following, the synthesis reference is Langmuir2017,33, 3304-; subsequently, 9.4547g of p-phenylenediamine (0.0874mol) and 7.64g of 2,5' -bis 4- (aminophenyl) pyrimidine (0.0291 mol; synthetic reference Journal of Materials science52.16(2017):9895-9906.) were added and stirred at constant temperature for 2 hours until they were completely dissolved.

(2) 29.12g (0.0991mol) of 3,3',4,4' -biphenyltetracarboxylic dianhydride was added to the reaction system, and after 10 hours at 35 ℃, 5.146g (0.0175mol) of 3,3',4,4' -biphenyltetracarboxylic dianhydride was added, and the mixture was stirred at constant temperature for 15 hours, and then the stirring was stopped, and the temperature was reduced to obtain a polyamic acid solution having a solid content of 25% and a viscosity of 8142cP (20 ℃) as measured by a DV-S rotor viscometer.

(3) Preparing a film by a coating method, wherein the thickness of a wet film coating is 120 mu m, drying and forming under reduced pressure, cyclizing at 100 ℃, 300 ℃ and 400 ℃ for 30min respectively, and naturally cooling to room temperature. The thickness of the obtained polyimide film is 25 mu m, the tensile strength is 350MPa, the glass transition temperature is 372 ℃, the TGA analysis 5% thermal decomposition temperature is 605 ℃, and excellent mechanical properties and heat resistance are shown.

Example 2

(1) Adding 180mL of N, N '-dimethylacetamide (the water content is less than 100ppm) and 4.06g of ammonium bifendate surfactant (0.005mol, the structure is shown as follows, and the synthesis refers to chemistry select,2018,3(17):4712-4719.) into a 250mL three-neck flask in sequence, heating to 50 ℃, and stirring until the N, N' -dimethylacetamide and the ammonium bifendate surfactant are completely dissolved; then, 14.63g (0.0732mol) of 4,4' -diaminodiphenyl ether and 10.9431g (0.0488mol) of 2- (4-aminophenyl) -5-aminobenzimidazole were added thereto, and stirred at a constant temperature for 2 hours until they were completely dissolved.

(2) 26.60g (0.122mol) of pyromellitic dianhydride was added to the reaction system, and after 12 hours at 30 ℃ the reaction was carried out, 2.6609g (0.0122mol) of pyromellitic dianhydride was added, and after stirring at constant temperature for 15 hours, the temperature was lowered to obtain a polyamic acid solution having a solid content of 22% and a reaction solution viscosity of 7039cP (20 ℃) as measured by DV-S rotor viscometer.

(3) The film is prepared by coating method, the wet film thickness is 120 μm, after decompression drying and forming, processing for 10min at 100 ℃, 280 ℃ and 350 ℃, and naturally cooling to obtain the polyimide film. The film thickness is 22 μm, the tensile strength is 220MPa, the glass transition temperature is 368 ℃, the TGA analysis 5% thermal decomposition temperature is 582 ℃, and the excellent mechanical property and heat resistance are shown.

Example 3

(1) Adding 180mL of N, N' -dimethylacetamide (the water content is less than 100ppm) and 2.32g of diphenyl ether carboxylic acid ammonium salt surfactant (0.003mol, the structure is shown as follows, and the synthesis is referred to chemistry select,2018,3(17):4712-4719.) in sequence into a 250mL three-neck flask, heating to 50 ℃, and stirring until the mixture is completely dissolved; then, 12.86g (0.1189mol) of m-phenylenediamine and 15.85g (0.0793mol) of 4,4' -diaminodiphenyl ether were added thereto and stirred at a constant temperature for 2 hours until they were completely dissolved.

(2) 38.91g (0.1784mol) of pyromellitic dianhydride was added to the reaction system, and after 12 hours at 30 ℃, 4.324g (0.0198mol) of pyromellitic dianhydride was added, and after stirring at constant temperature for 18 hours, the temperature was lowered to obtain a polyamic acid solution having a solid content of 28%, and a reaction solution viscosity of 9150cP (20 ℃) as measured by a DV-S rotor viscometer.

(3) The film is prepared by coating method, the wet film thickness is 100 μm, after decompression drying and forming, processing for 10min at 100 ℃, 280 ℃ and 350 ℃, and naturally cooling to obtain the polyimide film. The film has a thickness of 25 μm, a tensile strength of 230MPa, a glass transition temperature of 348 ℃, a TGA analysis 5% thermal decomposition temperature of 570 ℃, and shows excellent mechanical properties and heat resistance.

Comparative example 1

When 2,5 '-bis 4- (aminophenyl) pyrimidine and 3,3',4,4 '-biphenyltetracarboxylic dianhydride were polymerized in N, N' -dimethylacetamide as a solvent at 10 ℃ for 6 hours to give a polymer having a viscosity of about 1170000cP (20 ℃) at a diamine/dianhydride molar ratio of 1:1 and a solid content of 13.5%, it was difficult to perform coating processing.

Comparative example 2

Referring to the Kapton-series film of Dupont, 4 '-diaminodiphenyl ether and pyromellitic dianhydride were polymerized in N, N' -dimethylacetamide as a solvent at 10 ℃ for 10 hours to obtain a polyamic acid having a viscosity of about 870000cP (20 ℃) when the molar ratio of diamine to dianhydride was 1:1 and the polyamic acid had a solid content of 20%, which made it difficult to perform coating processing.