Domestic PTFE high-performance fiber fills domestic gaps
High-performance polytetrafluoroethylene (polytetrafluoroethylene) fiber materials have been used in the national economy due to their excellent high and low temperature stability, chemical stability, electrical insulation, non-adhesion, weather resistance, fire protection, self-lubricating and other properties. It has been widely used in many fields and has become the preferred material in environmental protection, filtration, construction, aerospace and other fields.
Due to the nature of polytetrafluoroethylene itself, the manufacturing of polytetrafluoroethylene fibers cannot simply adopt the molding methods of general thermoplastic polymer materials (such as extrusion molding), and this technical bottleneck is also the long-term inability to produce polytetrafluoroethylene fibers in our country. The important reason for the polytetrafluoroethylene fiber is that the researchers of this project independently developed the film splitting method to produce polytetrafluoroethylene fiber. That is, the expanded polytetrafluoroethylene film that meets certain conditions is first prepared through a three-dimensional station stretching method, and the polytetrafluoroethylene film is After the vinyl fluoride film is slit, it is made into the required polytetrafluoroethylene fibers through a certain stretching and heat treatment process.
Thousand-ton production capacity has been formed
The expert appraisal committee for this appraisal event has a strong lineup. The director and deputy director of the appraisal committee are respectively served by three academicians: Sun Jinliang, Jiang Shicheng, and Zhang Yaoming. They come from the fields of chemical fiber materials, industrial fabrics, environmental protection, chemical industry, etc. Eleven well-known experts agreed that the project is a major integrated innovation in my country’s high-performance fiber finishing technology, production equipment, product development, etc. It has a demonstration effect and the overall technology has reached the international advanced level.
Experts believe in their appraisal opinions that the project has created a PTFE uniform station finishing filmmaking process technology, independently developed and integrated an innovative complete set of production equipment for PTFE membranes and fibers, and has been operating stably. Form a thousand-ton production capacity. This scientific research result has independent intellectual property rights. It has applied for 10 invention patents and 4 have been authorized. It has significant social and economic benefits and broad market application prospects.
Ye Yongmao, consultant to the China Chemical Fiber Industry Association and professor-level senior engineer, told reporters: “The National Development and Reform Commission clearly listed the development and production of polytetrafluoroethylene fibers and products as one of the priorities in this year’s “Industrial Structural Adjustment Guidance Catalog” , in the first year of the ‘Twelfth Five-Year Plan’, it is exciting to see the fruitful results of the project’s completion of unit serialization. “As a skeleton material with excellent performance, polytetrafluoroethylene fiber can promote the mass production of Nomex1313, aryl sulfone. The application of high-performance fibers such as polyester and polyphenylene sulfide fibers in filter materials can accelerate the transformation of the economic development model of China’s chemical fiber industry, promote the structural adjustment, optimization and upgrading of the chemical fiber industry, and improve and develop the modern industrial system.
Ye Yongmao introduced that the film splitting method is used to produce polytetrafluoroethylene fibers and their application products, which mainly include polytetrafluoroethylene long fibers and polytetrafluoroethylene short fibers. Products developed from polytetrafluoroethylene long fibers include: long Fiber spinning yarn, PTFE sewing thread, PTFE dental floss, PTFE long fiber reinforced net specially used for chlor-alkali engineering, as well as PTFE-based cloth and PTFE-based cloth produced using PTFE fiber. Vinyl fluoride coated needle felt filter media, etc. The PTFE long and short fiber product technology produced by this project is at the internationally advanced level, and the product price is about 35% of similar foreign products, which greatly reduces the production cost of domestic users and provides the basis for my country’s environmentally friendly mass application of high-performance PTFE. Vinyl fiber lays the foundation.
Breaking the technological blockade of developed countries
According to Dr. Hao Xinmin, a senior engineer at the General Logistics Military Equipment Research Institute who participated in the research and development, because polytetrafluoroethylene is insoluble in any solvent, and the macromolecular chains are arranged in a straight line, it is highly rigid and has high viscosity above the melting point, making it impossible to adopt traditional methods. Solution method or melt spinning has become a major technical problem in the field of deep finishing of PTFE materials, and has also become a technical bottleneck in the application of PTFE materials in my country.
At present, only a few companies in the world have mastered the production technology of polytetrafluoroethylene fiber. The main production processes include carrier spinning method and paste extrusion method. However, these companies have implemented a technical blockade against my country for a long time, and The product is expensive, which greatly increases the application cost of PTFE fiber, thus severely restricting the progress and application development of PTFE fiber.
Starting from the analysis of only a few foreign production samples, a difficult exploration and arduous entrepreneurial process that lasted several years began. It is reported that a research group composed of enterprises, scientific research institutions and users has researched and designed the long and short fiber production process of polytetrafluoroethylene film splitting method, and developed a temperature gradient controlled non-isovelocity, variable effective width, multi-stretch polytetrafluoroethylene In the production process of ethylene fiber, we developed high-strength special-shaped polytetrafluoroethylene long fibers and short fibers, which solved the problem of “doubling” of polytetrafluoroethylene short fibers; we developed multi-angular film-cracked long fiber cutters and wear-resistant diamond short fibers. Key devices such as fiber slitting needle rollers and dental floss film splitting and slicing molding have been designed and sorted out: spiral extruder, two-roller calender, non-isovelocity stretching machine, gradient temperature control variable effective width stretching machine, film split length We have a complete set of production equipment such as fiber slitting machines, short fiber slitting machines, fiber extrusion drafting machines, and curling machines, and have established large-scale production lines; we have developed and produced “ひ”-shaped polytetrafluoroethylene dental floss, high-strength pure polyethylene floss, etc. PTFE gradient membrane filter materialAll these process technologies, series of products and production equipment have not been reported in similar or identical literature at home and abroad, and are novel and innovative. The product novelty search further proves that the PTFE fiber produced has filled the domestic gap, the performance of PTFE fiber is at the international leading level, and the PTFE fiber application products are at the internationally advanced and domestic leading level.
Ideal material for dust removal filter media
Fang Aimin, director of the Dust and Ash Removal Research Institute of the Guodian Environmental Protection Research Institute and a professor-level senior engineer, said: “This major breakthrough in domestic PTFE fiber production technology has successfully broken the foreign monopoly on our products and technology for many years. The blockade will trigger the upgrading of environmentally friendly processes and materials, which is of great social significance and has achieved important economic benefits at the critical stage of the country’s promotion of the ‘Blue Sky Project’ during the ‘Twelfth Five-Year Plan’.”
According to Fang Aimin, an important application of the polytetrafluoroethylene fiber produced in this project is the preparation of polytetrafluoroethylene filter media for high-temperature corrosive flue gas dust removal. Nowadays, domestically produced PTFE filter materials have been widely used in waste incineration, coal-fired power plants, steel industries and other industries. They are one of the key materials for my country to achieve energy conservation and emission reduction. At the same time, PTFE filter materials can also be used in In the field of gas-solid two-phase separation in corrosive high-temperature environments, it can be used as a filter separation material.
Currently, there are more than 40 sets of municipal solid waste incinerators and hazardous solid waste incinerators in my country, all of which use PTFE dust removal filters produced with the PTFE long and short fiber products developed in this project as raw materials. The total filtration area reaches more than 700,000 square meters, and the total amount of polytetrafluoroethylene fibers used is approximately 595.31 tons. For example, in the whole year of 2009, 40 tons of polytetrafluoroethylene long fibers were used in the production of bag dust collector filter materials for waste incinerators, and the amount of short fibers reached 240 tons, accounting for 91% of the total waste incineration industry. %above.
In the electric power industry, 9 power plants have used filter bag base fabrics made of PTFE long fibers produced by this project, with a total area of 245,000 square meters, and the total weight of PTFE fibers used is approximately is 36.75 tons. PTFE vinyl cloth provides key support for the 30,000-hour service life of filter materials in China’s power industry, and currently accounts for more than 50% of the market. The pure polytetrafluoroethylene fiber-coated filter material has a continuous use temperature of up to 250°C and an instant working temperature of 280°C. It is acid and alkali resistant, and will not be hydrolyzed or oxidized. The service life is up to 4 years, which is far longer than that of ordinary film-coated filter materials.
According to reports, PM2.5 refers to particulate matter in the atmosphere with a diameter less than or equal to 2.5 microns, also known as particulate matter that can enter the lungs. It has an important impact on air quality and visibility. Compared with coarser atmospheric particles, PM2.5 has a smaller particle size, is rich in a large amount of toxic and harmful substances, stays in the atmosphere for a long time, and is transported over a long distance, so it has a greater impact on human health and the quality of the atmospheric environment.
In most areas of China, especially in North China, where industry is concentrated, PM2.5 accounts for most of the weight of suspended particulate matter in the air. PM2.5 is also the main cause of the haze climate. In the past, PM2.5 was not included in my country’s air environment quality standards.
The Ministry of Environmental Protection recently announced the “Gravity Method for Determination of Ambient Air PM10 and PM2.5”, which for the first time regulates the measurement of PM2.5 particles suspended in the air with a diameter of less than or equal to 2.5 microns. Dust removal products using polytetrafluoroethylene cloth and its film-coated filter material have a filtration efficiency of up to 99.99% for PM2.5.
All of the above have made great contributions to my country’s implementation of energy conservation and emission reduction policies, enabling our country to no longer be controlled by others in the key field of polytetrafluoroethylene filter materials, and saving the country’s environmental protection investment costs.
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