Iron fiber (Yilm) fiber is a fully aromatic polyimide fiber. It is divided into two types: ordinary heat-resistant type and high-strength type. The former is used for dust filter bags and clothing. This type of polyimide fiber was developed in Jilin at the end of the 20th century. With the support of the Provincial Department of Science and Technology and the Military Project of the Academy of Sciences, the research started by the Changchun Institute of Applied Chemistry of the Chinese Academy of Sciences (Figure 6-5). Initially, the Changchun Institute of Applied Chemistry and the Jilin Provincial Textile Industry Design and Research Institute cooperated in the Changchun Institute of Applied Chemistry. A test line was established, and the polyimide solution was directly used for dry-wet spinning to obtain a fiber with a strength of about 2 GPa. Due to the high toxicity of the solvent system used in the fiber spinning process, the viscosity of the spinning solution is unstable at high temperatures. It is difficult to realize large-scale production. Therefore, after completing the designated tasks, the continued research on the spinning method was terminated, and the research work on spinning from the polyamic acid solution was started.
In 2008, Shenzhen Huicheng Electric Co., Ltd. began to cooperate with Changchun Institute of Applied Chemistry and established Changchun Gaoqi Polyimide Materials Co., Ltd. (referred to as Gaoqi Company), and began the industrialization research of polyimide fibers. Taking into account the market's demand for ordinary heat-resistant fibers, the research on the phthalic anhydride/diphenyl ether diamine system was first started. A method of slowly raising the temperature in an oven for imidization after drying at low temperature. In order to meet the requirements of enterprises to quickly form production capacity, I once discussed technical cooperation with Russian Liersot Company, and visited some equipment, and found that their production capacity was only a few tons in scale, the process was not continuous, and the 20t scale The cost of technology transfer and some equipment is as high as 8.5 million euros, which is equivalent to 85 million yuan at the exchange rate at the time. So it was decided that the company re-employed technicians, ordered equipment with production capacity, and switched to wet spinning. After overcoming key technical problems such as polymerization, drying, imidization, and stretching, at the end of 2009, a fully continuous process of spinning polyimide fiber from polyamic acid solution was realized, and the fiber strength reached 0.57~ 0.71GPa. However, this fiber is not suitable for textile requirements due to its high rigidity. So we started to solve the problem of fiber structure, technology and crimping. In 2010, the problem of fiber spinnability was solved by adding a third monomer, and the design and manufacturing of a 300t-scale standard production line was completed. Imine Materials Co., Ltd. has built a 160m-long polyimide fiber full-continuous production line with a scale of 1,000 tons.
In 2012, Gaoqi Company started the development of high-strength polyimide fiber again, obtained polyimide fiber with strength of 2.5~3GPa and modulus of 70~120GPa, and started small-scale production. For the above-mentioned polyimide fibers that have not been industrialized due to solvent toxicity and other reasons, Gaoqi Company switched to a polyamic acid solution with DMAc as a solvent, and wet spinning, which can also obtain a strength of 2.3~2.5GPa. In 2012, Gaoqi Company developed polyimide fiber Yilun 95 for clothing. In addition to good spinnability, this fiber also has the same warmth retention property as cashmere. Flame retardancy, antibacterial performance equivalent to silver-plated fiber, tested by Oeko-Tex standard100, it is considered to have baby-level human affinity and other characteristics, which can replace down, and has been used in outdoor clothing, special clothing, bedding, blankets, etc. .