阅读说明：本技术 芳香族聚噁二唑薄膜及其制备方法 (Aromatic polyoxadiazole film and preparation method thereof ) 是由 张再兴 林红卫 乔志勇 李文涛 舒友 胡扬剑 于 2019-12-09 设计创作，主要内容包括：本发明涉及一种芳香族聚噁二唑薄膜及其制备方法,包括以下步骤：以芳香族二甲酸化合物和肼盐为单体,在发烟硫酸中进行缩聚反应得到芳香族聚噁二唑溶液；将所述芳香族聚噁二唑溶液经衣架式流延模具挤出,然后输送至稀硫酸凝固浴中进行凝固成型,得到凝固的含酸湿态初生流延薄膜；将所述含酸湿态初生流延薄膜进行洗涤后,得到不含硫酸的初生流延薄膜；将所述不含硫酸的初生流延薄膜进行张紧干燥,在200～350℃进行热定型处理,并进行切边、卷绕,得到所述芳香族聚噁二唑薄膜。该芳香族聚噁二唑薄膜可广泛用作耐高温电绝缘薄膜、耐高温绝缘纸/薄膜复合材料、覆铜薄膜、耐高温渗透膜、碳膜基材及航空航天材料等。(The invention relates to an aromatic polyoxadiazole film and a preparation method thereof, wherein the preparation method comprises the following steps: carrying out polycondensation reaction in fuming sulfuric acid by taking an aromatic dicarboxylic acid compound and a hydrazine salt as monomers to obtain an aromatic polyoxadiazole solution; extruding the aromatic polyoxadiazole solution through a coat hanger type casting die, and then conveying the solution into a dilute sulfuric acid solidification bath for solidification forming to obtain a solidified acid-containing wet primary casting film; washing the acid-containing wet primary casting film to obtain a primary casting film without sulfuric acid; and tensioning and drying the sulfuric acid-free nascent casting film, carrying out heat setting treatment at 200-350 ℃, and carrying out edge cutting and winding to obtain the aromatic polyoxadiazole film. The aromatic polyoxadiazole film can be widely used as a high-temperature-resistant electric insulating film, a high-temperature-resistant insulating paper/film composite material, a copper-clad film, a high-temperature-resistant permeable film, a carbon film base material, an aerospace material and the like.)

1. A preparation method of an aromatic polyoxadiazole film is characterized by comprising the following steps:

carrying out polycondensation reaction in fuming sulfuric acid by taking an aromatic dicarboxylic acid compound and a hydrazine salt as monomers to obtain an aromatic polyoxadiazole solution;

extruding the aromatic polyoxadiazole solution through a coat hanger type casting die, and then conveying the solution into a dilute sulfuric acid solidification bath for solidification forming to obtain a solidified acid-containing wet primary casting film; the extrusion process of the coat hanger type casting die comprises the following steps: carrying out high-efficiency vacuum defoaming on the aromatic polyoxadiazole solution, conveying the aromatic polyoxadiazole solution to a coarse filter for coarse filtration, conveying the aromatic polyoxadiazole solution to a fine filter for fine filtration, conveying the aromatic polyoxadiazole solution to a coat hanger type mold, and extruding the aromatic polyoxadiazole solution in a slit of the mold onto a solidification carrier roller to form a sheet polyoxadiazole solution;

washing the acid-containing wet primary casting film to obtain a primary casting film without sulfuric acid;

and tensioning and drying the sulfuric acid-free nascent casting film, carrying out heat setting treatment at 200-350 ℃, and carrying out edge cutting and winding to obtain the aromatic polyoxadiazole film.

2. The preparation method according to claim 1, wherein the coarse filter has a filter mesh pore size of 40 μm to 80 μm and a filtration pressure of 1.0MPa or less, and the fine filter has a filter mesh pore size of 30 μm to 50 μm and a filtration pressure of 3.0MPa or less.

3. The preparation method according to claim 1, wherein the mass concentration of the dilute sulfuric acid in the dilute sulfuric acid coagulation bath is 20-50%, and the temperature of the dilute sulfuric acid in the dilute sulfuric acid coagulation bath is 20-60 ℃.

4. The preparation method according to claim 3, wherein the mass concentration of the dilute sulfuric acid in the dilute sulfuric acid coagulation bath is 40-45%, and the temperature of the dilute sulfuric acid in the dilute sulfuric acid coagulation bath is 40-50 ℃.

5. The method of claim 1, further comprising, before the step of washing, the steps of: and performing wet hot bath plasticization on the acid-containing wet primary casting film, and then performing unidirectional or bidirectional stretching.

6. The method for preparing the alloy material according to claim 5, wherein the process of the unidirectional or bidirectional stretching is as follows: and carrying out 1.1-4 times of unidirectional stretching on the acid-containing wet nascent casting film in unidirectional stretching equipment or carrying out 1.1-3 times of bidirectional stretching in bidirectional stretching equipment, wherein the stretching temperature is 40-50 ℃.

7. The preparation method according to claim 1, wherein the roughness of the inner surface of the runner of the coat hanger type mold is Ra ≤ 0.8 μm.

8. The preparation method according to claim 1, wherein the coat hanger type mold is made of 904 stainless steel, 904L stainless steel, Hastelloy B-2 alloy or Hastelloy C-276 alloy.

9. The manufacturing method according to claim 8, wherein the inner surface of the runner of the coat hanger type mold is finely ground, or is plated with a platinum layer or a gold layer of yellow platinum, and the plating thickness is 20 μm to 100 μm.

10. An aromatic polyoxadiazole film produced by the production method according to any one of claims 1 to 9.

Technical Field

The invention relates to the technical field of film preparation, in particular to an aromatic polyoxadiazole film and a preparation method thereof.

Background

Aromatic polyoxadiazole (POD for short) is an aromatic heterocyclic polymer material with good electrical insulation, heat resistance, oxidation resistance and other properties, is insoluble in general organic solvents and most inorganic solvents, is only decomposed at high temperature and is not melted, and therefore, has wide application prospects in the fields of high temperature resistance, electrical insulation and the like. However, because of the severe synthesis conditions, poor flowability and poor processability, the development efforts in the synthesis of POD polymers and the molding of materials such as films and fibers have been relatively small, and particularly the efforts in the film molding have been rare.

In the 60 s of the 20 th century, american scientists first initiated research on the preparation, structure and properties of aromatic polyoxadiazoles, and then POD polymers received much attention for their good properties. The POD is prepared by a two-step method generally, namely, polyhydrazide is synthesized firstly, and the POD material is formed by high-temperature dehydration and cyclization after processing and molding. The method has the advantages of complex technical route, high raw material cost, more structural defects of the material and poor mechanical property. At present, the two-step method is mainly limited to laboratory research and is used for preparing photoelectric materials and the like, but documents for preparing high-temperature resistant and functional films by using POD are not reported.

Disclosure of Invention

Accordingly, there is a need for a method for producing an aromatic polyoxadiazole film having better properties.

A preparation method of an aromatic polyoxadiazole film comprises the following steps:

carrying out polycondensation reaction in fuming sulfuric acid by taking an aromatic dicarboxylic acid compound and a hydrazine salt as monomers to obtain an aromatic polyoxadiazole solution;

extruding the aromatic polyoxadiazole solution through a coat hanger type casting die, and then conveying the solution into a dilute sulfuric acid solidification bath for solidification forming to obtain a solidified acid-containing wet primary casting film; the extrusion process of the coat hanger type casting die comprises the following steps: carrying out high-efficiency vacuum defoaming on the aromatic polyoxadiazole solution, conveying the aromatic polyoxadiazole solution to a coarse filter for coarse filtration, conveying the aromatic polyoxadiazole solution to a fine filter for fine filtration, conveying the aromatic polyoxadiazole solution to a coat hanger type mold, and extruding the aromatic polyoxadiazole solution in a slit of the mold onto a solidification carrier roller to form a sheet polyoxadiazole solution;

washing the acid-containing wet primary casting film to obtain a primary casting film without sulfuric acid;

and tensioning and drying the sulfuric acid-free nascent casting film, carrying out heat setting treatment at 200-350 ℃, and carrying out edge cutting and winding to obtain the aromatic polyoxadiazole film.

In one embodiment, the aperture of the filter screen of the coarse filter is 40-80 μm, the filtering pressure is less than or equal to 1.0MPa, the aperture of the filter screen of the fine filter is 30-50 μm, and the filtering pressure is less than or equal to 3.0 MPa.

In one embodiment, the mass concentration of the dilute sulfuric acid in the dilute sulfuric acid coagulation bath is 20-50%, and the temperature of the dilute sulfuric acid in the dilute sulfuric acid coagulation bath is 20-60 ℃.

In one embodiment, the mass concentration of the dilute sulfuric acid in the dilute sulfuric acid coagulation bath is 40-45%, and the temperature of the dilute sulfuric acid in the dilute sulfuric acid coagulation bath is 40-50 ℃.

In one embodiment, the step of washing further comprises the following steps: and performing wet hot bath plasticization on the acid-containing wet primary casting film, and then performing unidirectional or bidirectional stretching.

In one embodiment, the process of unidirectional or bidirectional stretching is: and carrying out 1.1-4 times of unidirectional stretching on the acid-containing wet nascent casting film in unidirectional stretching equipment or carrying out 1.1-3 times of bidirectional stretching in bidirectional stretching equipment, wherein the stretching temperature is 40-50 ℃.

In one embodiment, the roughness of the inner surface of the flow channel of the coat hanger type mould is Ra less than or equal to 0.8 μm.

In one embodiment, the coat hanger type die is made of 904 stainless steel, 904L stainless steel, Hastelloy B-2 alloy or Hastelloy C-276 alloy.

In one embodiment, the inner surface of the flow channel of the clothes rack type mould is finely ground, or is plated with a platinum layer or a yellow platinum layer, and the plating thickness is 20-100 μm.

The invention also provides an aromatic polyoxadiazole film which is prepared according to the preparation method.

The POD polymer solution is easy to solidify and form in the dilute sulphuric acid solution, and has tensile property (can be stretched by more than 3 times) incomparable with the solidification process of polyimide, aromatic polyamide and the like, and the POD can be processed into a high-temperature resistant, electric insulating and functional film with the thickness of dozens of micrometers to hundreds of micrometers through the technical route of POD polymerization → casting → solidification and forming → washing → drying and shaping → winding and forming, and the mechanical property, the high-temperature resistant, the electric insulating and other properties of the POD polymer solution are comparable with those of a polyimide film (such as Kapton), but the POD polymer solution has good price advantage. The preparation method of the invention uses the production technology of the viscose cellophane for reference, fully utilizes the characteristics of POD that POD is easy to be uniformly solidified and formed and can be highly stretched, and can achieve the expected purpose through high-temperature shaping. The prepared film has the thickness of 20-1000 microns, the tensile strength of 50-400 MPa, the elongation at break of 20-80 percent, the initial decomposition temperature of more than 480 ℃ and the electric breakdown strength of 100-300 kV. The film can be widely used as a high-temperature-resistant electric insulating film, a high-temperature-resistant insulating paper/film composite material, a copper-clad film, a high-temperature-resistant permeable film, a carbon film base material, an aerospace material and the like.

Detailed Description

In order that the invention may be more fully understood, a more particular description of the invention will now be rendered by reference to specific embodiments thereof that are illustrated in the appended drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

The preparation method of the aromatic polyoxadiazole film of the embodiment of the invention comprises the following steps of S1-S4:

s1, carrying out polycondensation reaction in fuming sulfuric acid by taking an aromatic dicarboxylic acid compound and a hydrazine salt as monomers to obtain an aromatic polyoxadiazole solution.

And S2, extruding the aromatic polyoxadiazole solution through a coat hanger type casting die, and conveying the solution into a dilute sulfuric acid solidification bath for solidification forming to obtain a solidified acid-containing wet primary casting film. The extrusion process of the coat hanger type casting die comprises the following steps: the preparation method comprises the steps of carrying out efficient vacuum defoaming on the aromatic polyoxadiazole solution, conveying the aromatic polyoxadiazole solution to a coarse filter for coarse filtration, conveying the aromatic polyoxadiazole solution to a fine filter for fine filtration, conveying the aromatic polyoxadiazole solution to a coat hanger type mold, and extruding the aromatic polyoxadiazole solution in a slit of the mold onto a solidification carrier roller to form the sheet polyoxadiazole solution.

And S3, washing the acid-containing wet primary casting film to obtain the primary casting film without sulfuric acid.

S4, tensioning and drying the sulfuric acid-free primary casting film, carrying out heat setting treatment at 200-350 ℃, and carrying out edge cutting and winding to obtain the aromatic polyoxadiazole film.

The POD polymer solution is easy to solidify and form in the dilute sulphuric acid solution, and has tensile property (can be stretched by more than 3 times) incomparable with the solidification process of polyimide, aromatic polyamide and the like, and the POD can be processed into a high-temperature resistant, electric insulating and functional film with the thickness of dozens of micrometers to hundreds of micrometers through the technical route of POD polymerization → casting → solidification and forming → washing → drying and shaping → winding and forming, and the mechanical property, the high-temperature resistant, the electric insulating and other properties of the POD polymer solution are comparable with those of a polyimide film (such as Kapton), but the POD polymer solution has good price advantage. The preparation method of the invention uses the production technology of the viscose cellophane for reference, fully utilizes the characteristics of POD that POD is easy to be uniformly solidified and formed and can be highly stretched, and can achieve the expected purpose through high-temperature shaping. The prepared film has the thickness of 20-1000 microns, the tensile strength of 50-400 MPa, the elongation at break of 20-80 percent, the initial decomposition temperature of more than 480 ℃ and the electric breakdown strength of 100-300 kV. The film can be widely used as a high-temperature-resistant electric insulating film, a high-temperature-resistant insulating paper/film composite material, a copper-clad film, a high-temperature-resistant permeable film, a carbon film base material, an aerospace material and the like.

In a specific example, the aperture of the filter screen of the coarse filter is 40-80 μm, the filtering pressure is less than or equal to 1.0MPa, the aperture of the filter screen of the fine filter is 30-50 μm, and the filtering pressure is less than or equal to 3.0 MPa. Preferably, the material of the coarse filter and the fine filter is 316L stainless steel (standard designation 022Cr17Ni12Mo 2).

In a specific example, the mass concentration of the dilute sulfuric acid in the dilute sulfuric acid coagulation bath is 20-50%, and the temperature of the dilute sulfuric acid in the dilute sulfuric acid coagulation bath is 20-60 ℃. Preferably, the mass concentration of the dilute sulfuric acid in the dilute sulfuric acid coagulation bath is 40-45%, and the temperature of the dilute sulfuric acid in the dilute sulfuric acid coagulation bath is 40-50 ℃.

In one specific example, the step of washing is preceded by the steps of: and (3) performing wet hot bath plasticization on the acid-containing wet primary casting film, and then performing unidirectional or bidirectional stretching. Specifically, the process of unidirectional or bidirectional stretching is as follows: carrying out 1.1-4 times of unidirectional stretching on the acid-containing wet nascent casting film in unidirectional stretching equipment or carrying out 1.1-3 times of bidirectional stretching in bidirectional stretching equipment, wherein the stretching temperature is 40-50 ℃.

In one specific example, the roughness of the inner surface of the runner of the clothes hanger type mould is Ra less than or equal to 0.8 μm, namely, the precision of a dark gloss surface is achieved, the surface smoothness is more than ▽ 10, and preferably, the surface smoothness is more than ▽ 14, namely, the mirror surface requirement is achieved.

In one specific example, the coat hanger type mold is made of 904 stainless steel (with the standard mark of 0Cr20Ni25Mo5Cu2), 904L stainless steel (with the standard mark of 00Cr20Ni25Mo5Cu2), Hastelloy B-2 alloy or Hastelloy C-276 alloy.

In one specific example, the inner surface of the flow channel of the clothes rack type mould is finely ground, or is plated with a platinum layer or a yellow platinum layer, and the plating thickness is 20-100 μm. Preferably, the distance between the die openings of the clothes rack type die is adjustable within the range of 0.2-0.6 mm, the processing temperature of the clothes rack type die is adjustable within the range of 30-120 ℃, and the preferable processing temperature is 70-90 ℃.

In one specific example, the material of the solidification carrier roller is 904 stainless steel (standard mark is 0Cr20Ni25Mo5Cu2), 904L stainless steel (standard mark is 00Cr20Ni25Mo5Cu2) or Polytetrafluoroethylene (PTFE), the outer surface of the solidification carrier roller can be plated with platinum or platinum gold, the thickness of the plating layer is 20-100 μm, the surface roughness of the plating layer reaches the precision of a dark gloss surface and above, namely Ra is less than or equal to 0.8 μm (the surface finish is more than ▽ 10), preferably, the surface roughness reaches the precision of invisible marks and above, namely Ra is less than or equal to 1.6 μm (the surface finish is more than ▽ 9), preferably, the diameter of the solidification carrier roller is between 400-1000 mm, and the solidification carrier roller can be communicated with circulating heat preservation water to ensure that the temperature of the roller surface is 30-60 ℃.

In a specific example, the aromatic dicarboxylic acid compound contains one or more of the following groups, specifically, terephthalic acid, and the like.

In a specific example, the molar ratio of fuming sulfuric acid, the aromatic dicarboxylic acid compound and the hydrazine salt is (3-6): 1.0 (1.03-1.1). Preferably, the aromatic dicarboxylic acid compound comprises at least two compounds, one of which is terephthalic acid, and the molar ratio of the terephthalic acid to the other aromatic dicarboxylic acid is (0.50-1.00): (0.1-0.5). It will be understood that the molar amount of oleum is based on the SO contained in the oleum₃In terms of moles of (A), SO₃The mass percentage of the component (A) is 20-40%. Preferably, the hydrazonium salt is hydrazine sulfate.

In one particular example, the polycondensation reaction is carried out in a three-stage process:

1) the reaction temperature of the first stage is 80-120 ℃, and the reaction time is 2-5 h;

2) the reaction temperature of the second stage is 110-140 ℃, the reaction time is 1-5 h, and a chain terminator is added when the second stage is finished;

3) the reaction temperature of the third stage is 130-160 ℃, and the reaction time is 0.5-3 h.

Preferably, the chain terminator is benzoic acid, and the addition amount of the chain terminator is 0.5 to 3 mole percent of the aromatic dicarboxylic acid in the reaction system of the polycondensation reaction.

The following are specific examples.