In the textile industry, the newly approved National Advanced Printing and Dyeing Technology Innovation Center, the National Advanced Functional Fiber Innovation Center established last year, and the National High-performance Medical Device Innovation Center, the National Integrated Circuit Characteristic Process and Packaging and Testing Innovation Center, and the National Rare Earth Functional Materials Innovation Center, which have been approved by the Ministry of Industry and Information Technology since this year, are all areas that the country urgently needs and must focus on achieving technological breakthroughs. It is related to the foundation of a manufacturing power.

Implementing the "innovation-driven development strategy", grasping the key and making up for shortcomings is the need for national development, and specifically, it is also the need to relieve some core technologies from the risk of being "stuck. For example, the strategic industry represented by carbon fiber must be independent and controllable, and the national power must be brought into play to plan and develop in a planned and step-by-step manner.

Wet spinning process of carbon fiber preparation with important strategic significance

High-performance polyacrylonitrile (PAN)-based carbon fiber is a new dual-use material related to national strategic security. It has been strictly embargoed by the international community for a long time. The research and development of key equipment fields have been severely restricted, and it is an important technology for carbon fiber for national defense equipment. The wet spinning process based is a key technical shortcoming in the research of domestic carbon fiber.

Due to the influence of carbon fiber precursor preparation technology, until the end of the last century, the development of domestic carbon fiber technology has been hovering at a low level of industrialization. Carbon fiber for structural composite materials of national defense equipment is completely dependent on imports, which brings great hidden dangers to national security and development. There is an urgent need to develop carbon fiber localization technology to meet the needs of high-end equipment in key areas of our country, so as to realize the independent guarantee of key materials.

PAN-based carbon fiber preparation has the longest process in the field of materials, including polymerization, spinning, pre-oxidation, carbonization (graphitization), surface treatment and other process links. Among them, the carbon fiber prepared by PAN solution wet spinning process has a unique surface groove structure, which is beneficial to improve the interface properties of carbon fiber resin matrix composites as structural materials. China's defense field, represented by aerospace, has long used wet spinning process to prepare carbon fiber. Therefore, the development of wet spinning process for carbon fiber preparation has important strategic significance and market value in China.

"Created a carbon fiber variety" and formed a series of products based on the wet spinning process.

Weihai Development Fiber Co., Ltd. takes the preparation of carbon fiber composite materials as the technical and industrial foundation, based on the dedication to the localization of national key strategic materials, based on the pursuit of independent control of key raw materials in the industrial chain, and devotes itself to PAN-based carbon fiber localization technology research and industrialization construction.

With the support of science and technology and industrialization plans of the Ministry of Science and Technology, Science and Industry Bureau, Development and Reform Commission, Ministry of Industry and Information Technology and other ministries and commissions, and under the traction of key model application development, aiming at the problems of fiber defect control, fiber surface cross-section morphology control, multi-spinning position/multi-tow process state consistency control, and carbon fiber performance/specification serialization technology research to meet high-end application requirements, weihai Development, in conjunction with Beijing University of Chemical Technology, Fudan University and other scientific research institutions, based on the independent innovation and original innovation of process technology, the independent innovation of new technology and industrialization technology for preparing carbon fiber precursor through dimethyl sulfoxide wet spinning process, combined with the re-innovation of key equipment, has achieved a number of key technological breakthroughs--

Break through the key technology of efficient preparation of high quality spinning solution and solve the problem of single defoaming of high solid content and high viscosity polymer solution;

The development of washing/pulling integrated combined drafting process and equipment, independent innovation of multi-spinning spinning new technology, effectively improve the quality consistency and stability of multi-spinning raw silk;

To develop an efficient precursor drawing process and equipment with temperature gradient characteristics, to achieve effective control of carbon fiber modulus, to meet the needs of the aviation field;

Successfully developed a new technology of hot-air interactive conveying pre-oxidation furnace, breaking the traditional four-temperature zone model, establishing a new technology of six-temperature zone, and breaking through the bottleneck of high-efficiency and long-term stable operation of 3-meter-wide pre-oxidation production equipment;

Development of a new type of low-denier PAN precursor spinning technology to achieve radial homogenization of low-denier precursors and structural optimization of high axial orientation;

The development of a fiber pre-oxidation technology with a controlled structural combination and the solution of the technical problems in the preparation of carbon fibers with medium and high moduli;

Research and development of a set of simulation design, manufacturing and operation of the tube of the localization of key equipment technology, to solve the different modulus of carbon fiber industrialization quality consistency problems.

Through systematic technical research, we have developed serialized technologies and products based on tensile strength, serialized technologies and products based on tensile modulus, and serialized technologies and products based on tow specifications, realizing large-scale production and large-scale application of high-performance carbon fiber, and establishing a complete technical research and development and thousand-ton industrialization system for preparing high-strength carbon fiber based on wet spinning process.

The mechanical performance indexes of T300 and T800 carbon fiber products developed and produced by this project exceed the level of similar products of Japan Dongli Company, and their performance stability is equivalent to them. The 300 m/min spinning speed in the breakthrough multi-spinning position state has increased the industrial wet spinning speed by more than 1.5 times, thus establishing innovative confidence for the industry. However, the tensile strength and modulus of the original and innovative new high-strength carbon fiber product reach the level of Japan's Toray T700S carbon fiber, and the interface performance of the composite material is better than that of the product (Toray has only T700 grade of dry and wet method and no T700 grade of wet method). Experts believe that "a carbon fiber variety with high strength of T700 grade carbon fiber and excellent surface structural properties of T300 grade carbon fiber has been created".

To practice the development strategy of domestic carbon fiber with strong strength

Weihai expands the stabilized carbon fiber products based on wet spinning process, which have been widely used in national defense construction such as aviation, aerospace, weapons, electronics, wind power and other industrial high-end equipment, civil engineering and other fields. Weihai is the main supplier of carbon fiber for national defense and the first preferred and largest supplier in aviation field in China. It not only solves the problems of "availability", "availability" and "ease of use" of localization of structural carbon fiber, it broke the foreign monopoly in this field, realized the independent guarantee of domestic key strategic materials, and became the largest carbon beam supplier of Vestas, an international leading wind power enterprise, in China. With its unremitting efforts, Weihai Development has practiced the principle that "key technologies cannot be acquired, bought or sought. Only by mastering key core technologies in our own hands can we fundamentally safeguard national economic security, national defense security and other security", and adhere to the path of independent and controllable development of key technologies.

As for the "industrialized preparation technology of high-strength PAN-based carbon fiber based on wet spinning process", experts appraised that: "the project is based on original innovation and independent innovation, realizing independent innovation based on DMSO intermittent polymerization and wet spinning, and stably preparing high-strength/high-strength medium-mode PAN-based carbon fiber on a large scale, covering GQ3522(T300 grade), GQ4522 (T700 grade) and Q5526 (T800 grade series products, it supports the application of composite materials for key batch models of national defense. The overall results have reached the international advanced level". The project won the first prize for scientific and technological progress of the China Textile Industry Federation in 2019.

Weihai has always attached importance to the expansion of intellectual property strategy. In the field of PAN wet spinning to prepare high-performance carbon fiber, it has been authorized with 11 national invention patents and 18 utility model patents, and has led the compilation of China's first national standard of "polyacrylonitrile-based carbon fiber" and formulated a series of enterprise product standards.

In the face of carbon fiber, a very important and promising sunrise industry, Weihai development will adhere to the purpose of "revitalizing the national industry and adhering to the principle of serving the country by industry", continue to take technological innovation as the core, constantly improve its own strength, and strive to become a manufacturer of carbon fiber industry chain with global competitiveness.