阅读说明：本技术 一种高性能聚苯并咪唑纤维及其制备方法 (High-performance polybenzimidazole fiber and preparation method thereof ) 是由 武德珍 孙国华 牛鸿庆 张梦颖 田国峰 于 2019-09-27 设计创作，主要内容包括：本发明涉及一种高性能聚苯并咪唑纤维及其制备方法,包括如下步骤：在氮气保护下,将二酸与四胺单体或者二酯与四胺单体在多聚磷酸中进行聚合反应,制备固含量为3-20％的聚苯并咪唑(PBI)纺丝溶液、将溶剂为多聚磷酸的聚苯并咪唑纺丝溶液进行过滤和真空脱气,然后由氮气加压或者螺杆挤出机输送至纺丝组件中,按照一体化纺丝工艺进行纺丝,所得纤维经空气段后进入凝固浴,经导丝辊牵引在凝固浴中凝固,进行充分洗涤后,再经三段或以上的炉段进行干燥和热牵伸,最后进行收丝,即可获得聚苯并咪唑纤维。本发明的制备方法对于制备聚苯并咪唑纤维而言是一种开创性的方法,最终得到了高品质的聚苯并咪唑纤维。(The invention relates to a high-performance polybenzimidazole fiber and a preparation method thereof, and the preparation method comprises the following steps: under the protection of nitrogen, diacid and a tetramine monomer or diester and a tetramine monomer are subjected to polymerization reaction in polyphosphoric acid to prepare a Polybenzimidazole (PBI) spinning solution with the solid content of 3-20%, the polybenzimidazole spinning solution with the polyphosphoric acid as a solvent is subjected to filtration and vacuum degassing, then the polybenzimidazole spinning solution is conveyed to a spinning assembly through a nitrogen pressurizing or screw extruder, spinning is carried out according to an integrated spinning process, the obtained fiber enters a coagulating bath after passing through an air section, is drawn by a godet roller to be coagulated in the coagulating bath, is fully washed, is dried and thermally drawn through three or more furnace sections, and finally, the polybenzimidazole fiber is obtained. The preparation method of the invention is an innovative method for preparing polybenzimidazole fiber, and finally high-quality polybenzimidazole fiber is obtained.)

1. A high-performance polybenzimidazole fiber is characterized in that diacid and a tetramine monomer or diester and a tetramine monomer are polymerized in polyphosphoric acid and then spun to obtain the high-performance polybenzimidazole fiber, wherein the skeleton structure of the polybenzimidazole fiber comprises a benzimidazole structural unit, the tensile strength of the high-performance polybenzimidazole fiber is 0.1-2.0GPa, and the thermal decomposition temperature is 400-650 ℃.

2. A preparation method of high-performance polybenzimidazole fiber is characterized in that polybenzimidazole fiber is obtained by starting from a polybenzimidazole solution with polyphosphoric acid as a synthetic solvent, continuously performing solidification, cleaning, drying and hot drawing processes on the fiber according to an integrated spinning process, and finally rolling the fiber, and specifically comprises the following steps:

a: degassing, feeding and prepolymerization

Under the protection of nitrogen, heating by using a heating device, heating polyphosphoric acid at 60-150 ℃ for 0.5-2h for degassing, then sequentially adding diacid and tetramine monomer or diester monomer and tetramine monomer and phosphorus pentoxide into a reaction vessel, wherein the diacid and tetramine monomer or diester and tetramine monomer are respectively proportioned according to the total molar ratio of 1: 0.85-1: 1.15, and carrying out prepolymerization on the reaction system at 140-180 ℃ for 0.5-5h to obtain a prepolymerization material;

b: post-polymerization and deaeration

After the step A is finished, setting the temperature of a heating device to be 200-250 ℃ for polymerization, wherein the reaction time is 0.5-20h, supplementing phosphorus pentoxide for 1-5 times in the polymerization process, finally obtaining the polybenzimidazole spinning solution with the solid content of 3-20% and the solvent of polyphosphoric acid, and then filtering and vacuum degassing;

c: spinning and coagulating

And C, spinning according to an integrated spinning process, conveying the polybenzimidazole spinning solution into a spinning assembly by nitrogen pressurization or a screw extruder to obtain a slurry protofilament, firstly passing through a section of air gap, then solidifying the fiber in a coagulating bath after being drawn by a godet roller, fully cleaning the fiber by two or more sections of cleaning baths, then drying and hot drawing the fiber by three or more furnace sections, and finally collecting the fiber by winding equipment to obtain the polybenzimidazole fiber.

3. The method of claim 2, wherein: when the integrated spinning process is adopted, the coagulating bath and the cleaning bath are mixed solution of water or water and one or more of phosphoric acid, methanesulfonic acid, potassium hydroxide, sodium hydroxide and sodium bicarbonate.

4. The method of claim 2, wherein the diacid monomer of step a is: isophthalic acid (IPA), terephthalic acid (PTA), dipicolinic acid (DPA), 4-diphenyletherdicarboxylic acid (OBBA); the diester monomers are: dimethyl isophthalate (DMIP), dimethyl terephthalate (DMT); the tetramine monomer is as follows: 3,3' -Diaminobenzidine (DAB).

5. The method according to claim 2, wherein the heating device used in step A and step B is a microwave reaction heating device, a heat-collecting type constant temperature heating device or a digital display constant temperature electric jacket.

6. The process according to claim 2, characterized in that the phosphorus pentoxide content involved in step A and in step B is 80-86% of the total content of the mass at the end of the final reaction.

7. The method as claimed in claim 2, wherein in the spinning process of step C, the spinning temperature is controlled to be 140-220 ℃, and the spinning speed is controlled to be 2-200 m/min.

8. The process of claim 2, wherein the coagulation bath temperature in step C is 5-30 ℃ and the first and second sections of the cleaning bath are 10-100 ℃, and the number of furnace sections in the process can be adjusted according to the temperature setting and the time the fibers have passed in the cleaning bath.

9. The method according to claim 2, wherein the air gap in step C is 0.5-20cm, and the draft ratio during the heat treatment is 1-8.

10. The process of claim 2 wherein said furnace section of step C is comprised of a tubular furnace and the hot draw temperature is, in order: the first furnace section is 50-250 ℃, the second furnace section is 200-.

Technical Field

The invention relates to a polybenzimidazole fiber and a preparation method thereof, in particular to a method for continuously preparing high-performance organic fiber in one step by directly taking a polybenzimidazole solution of which a synthesis preparation solvent is polyphosphoric acid as a spinning solution.

Background

Polybenzimidazole fiber is an organic fiber with excellent comprehensive performance, has excellent performances of high temperature resistance, flame retardance, good chemical stability, good mechanical property, dielectric property, self-lubricating property, less toxic gas generation during combustion and the like, and is known as the king of flame retardance. The application field is very wide, and the method covers the fields of aerospace, military and national defense, fire protection, traffic communication, environmental protection and purification and the like.

The preparation method of the polybenzimidazole fiber at present utilizes a wet spinning process, firstly carries out polymerization to prepare polybenzimidazole, then obtains the solid such as polybenzimidazole powder or particles, then dissolves the obtained polybenzimidazole, prepares the polybenzimidazole fiber through the wet spinning, and carries out heat treatment after the fiber passes through a coagulating bath and a cleaning bath, thus obtaining the polybenzimidazole fiber. US patent nos. 3,619,453 and 4,814,228 both disclose wet spinning methods for preparing polybenzimidazole fibers, and mention that pressurized dissolution is required or a co-solvent such as lithium chloride is added to assist dissolution when preparing polybenzimidazole dope. The method is obviously complicated in process, and mainly needs to obtain polybenzimidazole firstly and then dissolve the polybenzimidazole to prepare spinning solution. The polybenzimidazole molecule has high rigidity, strong hydrogen bond among molecules and lack of side groups on a polymer molecular chain, so that the polybenzimidazole has poor solubility, and the spinning forming processing is difficult. This method limits the properties of polybenzimidazole fibers to some extent because polybenzimidazole having a higher molecular weight is more difficult to dissolve in organic solvents, and thus it is difficult to prepare high-strength, high-performance polybenzimidazole fibers. While US3,619,453 particularly emphasizes suitable solvents for polybenzimidazole dope including: dimethylacetamide, N-dimethylformamide, dimethylsulfoxide, and N-methylpyrrolidone, the most preferred solvent being dimethylacetamide, which is considered to be a very important solvent for the dissolution of the more rigid and molecular weight polybenzimidazole even though dimethylacetamide has a good solubility in organic solvents. The research efforts on polybenzimidazole fibers to date have limited their development and application due to the problems that exist.

Disclosure of Invention

The problem to be solved by the invention is to overcome the defects of the preparation method, and provide a preparation method for continuously preparing polybenzimidazole fiber in one step by directly using a polybenzimidazole solution of which the synthesis preparation solvent is polyphosphoric acid as a spinning solution.

One of the purposes of the invention is to provide a high-performance polybenzimidazole fiber material.

The second purpose of the invention is to provide a preparation method of high-performance polybenzimidazole fiber.

The invention provides a preparation method of high-performance polybenzimidazole fiber, which is characterized in that the polybenzimidazole fiber is obtained by starting from the synthesis of polybenzimidazole solution and adopting an integrated spinning process, and the fiber is continuously subjected to the processes of solidification, cleaning, drying and hot drawing and finally wound, and the preparation method specifically comprises the following steps:

a: degassing, feeding and prepolymerization

Under the protection of nitrogen, heating by using a heating device, heating polyphosphoric acid at 60-150 ℃ for 0.5-2h, then sequentially adding diacid and a tetramine monomer or diester and a tetramine monomer and phosphorus pentoxide into a reaction container, wherein the diacid monomer and the tetramine monomer or diester monomer and the tetramine monomer are mixed according to a total molar ratio of 1: 0.85-1: 1.15, and carrying out prepolymerization on a reaction system at 180 ℃ for 0.5-5h to obtain a prepolymerization material;

b: post-polymerization and deaeration

After the prepolymerization reaction is finished, setting the temperature of a heating device to 200-250 ℃ for polymerization, wherein the reaction time is 0.5-20h, supplementing phosphorus pentoxide for 1-5 times in the polymerization process, finally obtaining the polybenzimidazole spinning solution with the solid content of 3-20%, and then filtering and vacuum degassing;

c: spinning and coagulating

After polymerization and deaeration are completed, spinning is carried out according to an integrated spinning process, polybenzimidazole spinning solution is conveyed into a spinning assembly by nitrogen pressurization or a screw extruder to obtain slurry protofilaments, the slurry protofilaments firstly pass through a section of air gap, then the fibers are solidified in a solidification bath after being pulled by a godet roller, and then are fully cleaned by two or more sections of cleaning baths, and then are dried and thermally drawn by three or more sections of furnaces, and finally, the polybenzimidazole fibers are collected by winding equipment to obtain the polybenzimidazole fibers.

In this process, the diacid and tetraamine monomers or diester and tetraamine monomers used are the various diacid and tetraamine monomers or diester and tetraamine monomers used by those skilled in the art to synthesize polybenzimidazoles, and have the general formula:

diacid(s)

Diesters of benzoic acid

Wherein R represents the conventional structural groups in diacid, diester and tetramine monomers in the field, such as aromatic and heterocyclic structures and the like.

In the method, the coagulating bath and the cleaning bath are water or a mixed solution of water and one or more of the following solvents according to an integrated spinning process, and the solvents are phosphoric acid, methanesulfonic acid (MSA), potassium hydroxide, sodium hydroxide and sodium bicarbonate.

The diacid monomer in the step A is as follows: isophthalic acid (IPA), terephthalic acid (PTA), dipicolinic acid (DPA), 4-diphenyletherdicarboxylic acid (OBBA); the diester monomers are: dimethyl isophthalate (DMIP), dimethyl terephthalate (DMT); the tetramine monomer is as follows: 3, 3-diaminobenzidine.

The heating devices mentioned in the step A and the step B are a microwave reaction heating device, a heat collection type constant temperature heating device and a digital display constant temperature electric heating jacket.

The phosphorus pentoxide content involved in step a and in step B is in a percentage of 80% to 86% of the total content at the end of the final reaction.

And C, in the spinning process, the spinning temperature is controlled to be 140-220 ℃, and the spinning speed is controlled to be 2-200 m/min.

The temperature of the coagulation bath in the step C is 5-30 ℃, the temperature of the first section and the second section of the cleaning bath is 10-100 ℃, and in the process, the number of the furnace sections can be adjusted according to the temperature setting and the time of the fiber passing through the cleaning bath.

And C, the air gap is 0.5-20cm, and the drafting multiple is 1-8 in the heat treatment process.

The furnace section in the step C consists of a tubular hot furnace, and the hot drafting temperature is as follows: the first furnace section is 50-250 ℃, the second furnace section is 200-.

Compared with the prior art, the invention has the following excellent effects:

1. the invention prepares the polybenzimidazole fiber by one step from the synthesis of the polybenzimidazole solution according to an integrated spinning process, has simple process, short time and good continuity in the whole process, prepares the high-performance fiber by multi-section cleaning bath and multi-section heat treatment and drafting, realizes the continuity of the fiber process and is beneficial to large-scale generation.

2. The polybenzimidazole fiber is directly prepared by utilizing the polybenzimidazole solution, the method is simple, the monomer sources are wide, the adopted diacid and tetramine monomers or diester and tetramine monomers belong to domestic raw materials, the cost is low, and the adopted solvent and the coagulating bath solution can be recycled and reused without polluting the environment.

Detailed description of the invention

It should be noted that: the following examples are only for illustrating the present invention and are not to be construed as limiting the technical solutions described in the present invention, so that, although the present invention has been described in detail in the present specification with reference to the following examples, it will be understood by those skilled in the art that the present invention can be modified or substituted equally; all technical solutions and modifications thereof without departing from the spirit and scope of the present invention shall be covered by the claims of the present invention, such as diacid and tetramine monomers or diester and tetramine monomers in the art can achieve the objects of the present invention, and the following examples are only for illustration.

In the following examples, the monomer structures used are as follows: