Development trends and innovation directions of special fiber filter materials
Special fiber filter materials have been widely used in many industries of the national economy, especially in the fields of petrochemical industry, medicine, environmental protection and national defense. These materials show a diversified development trend, and commonly used are high-performance fiber nonwovens, hollow fiber membrane separation materials, activated carbon fibers, ion exchange fibers, metal chelate fibers, etc. The new development direction is multi-functionality, nanotechnology and diversification of materials.
In order to extend the life of filter bags and adapt to more stringent emission standards in the future, the future innovation direction is to use two different types of high-temperature-resistant fibers to complement each other, and to develop ultra-fine fiber varieties or special-shaped cross-section fibers to improve the filtration accuracy of the bags. There are also improvements in the polymer synthesis process abroad to improve the overall performance of the fiber. For example, Korean and Japanese companies have cooperated to develop a new synthesis process for PPS that does not contain chlorine raw materials to improve the corrosion resistance of the fiber. Japan’s high-temperature-resistant fiber manufacturers have been rapidly transforming and upgrading. Differentiated high-temperature-resistant fibers such as fine specifications, special-shaped cross-sections, and core-sheath composite yarns are the focus of production. About 70% of their products are exported to China.
10 high temperature resistant fiber properties and key points for filter material development
After years of independent research and development, our country has basically equipped various high-temperature resistant organic and inorganic fiber varieties required for high-temperature dust filter bags. Specific varieties include polyphenylene sulfide (PPS), polyimide (PI), intermediate Aramid fiber (m-AR), aramid fiber (PSA), melamine, polyoxadiazole (PODZ), polytetrafluoroethylene (PTFE), basalt (BA) and glass fiber (GF), only ketone anhydride Polyimide-like (P84) and aramid-imide fibers are still vacant, but can be replaced by the above fibers.
Different high-temperature-resistant fibers have different properties such as heat resistance and chemical resistance, and the prices are also different. Therefore, application manufacturers must consider the different characteristics suitable for the high-temperature exhaust of the factory and select personalized and cost-effective filter bag products. The German Leather and Plastic Sheet Research Institute, the Saxon Textile Research Institute and the Air Management and Refrigeration Research Institute have jointly studied the heat resistance of 10 types of fibers and the effects of various acid and alkali substances in different flue gases on fiber strength, as follows shown in the table.
(1) Heat resistance
The heat resistance test was exposed to an oven at 180°C for 500 hours. As a result, the PET fiber thermally decomposed and the GF-A fiber became brittle, making it unsuitable for long-term use under these conditions. The strength of PAI fiber drops to 50% but does not decompose. The situation for other fibers is shown below.
Strength of various fibers after being placed in a drying oven at 180 ℃
(2) Hydrolysis resistance
Hydrolysis resistance is measured by comparing the strength changes of fibers after moisture heat treatment. The results show that there is no change in the strength of PPS, m-AR, PSA and PTFE fibers. However, PI and fluffy Pohri S glass fibers have a significant loss of strength after being treated in a steam sterilizer for 72 hours. , so it can only be used to a limited extent in hot and humid environments. PET, GF-A, GF-B and BA fibers are all resistant to hydrolysis and will melt, degrade or become brittle, as shown in the figure below.
Strength changes of various fibers after being treated in a steam sterilizer for 72 hours
(3) Chemical resistance
Directly place the fiber into a concentrated acid and alkali solution at room temperature and below 70°C. The results are shown in the figure below.
Fiber strength in various chemicals at room temperature after 24 h
Fiber strength after 8 h and 16 h storage at 70 ℃
The strength changes of the fiber after being stored in each chemical for 24 hours, stored in a humid state at room temperature for a month, and placed in a drying oven at 180°C for 24 hours are shown in the figure below.
Fiber strength after placement under different conditions
The results obtained after the fiber was exposed to actual flue gas conditions for 60 hours are shown in the figure below. Some fibers cannot be separated and cannot be tested; PET fiber is completely damaged after 10 hours, while the strength of PPS, PAI, MF and PTFE fibers has no effect. No strength loss is noticed in PI, PSA, GF-A and BA fibers. The strength of the fluffy Pohri S fiber has increased.
Strength of various fibers after exposure to flue gas under various conditions
Extended reading: https://www.alltextile.cn/product/product-19-981.html
Extended reading:https://www.brandfabric.net/polyester-dobby-3-laminated-fabric/
Extended reading: https://www.china-fire-retardant.com/post/9403.html
Extended reading: https:// www.alltextile.cn/product/product-7-78.html
Extended reading: https://www.brandfabric.net/dobby-pongee-breathable-fabric/
Extended reading: https://www.yingjietex.com/product/DOBBY-PONGEE-Breathable-Fabric.html
Extended reading: https://www.alltextile.cn/product/product-48-270.html
Extended reading:https://www.yingjietex.com/product/800D-Polyester-DOBBY-OXFORD-Fabric.html
Extended reading: https://www.yingjietex.com/product/jacquard-Oxford-fabric.html
Extended reading: https://www.alltextile.cn/product/product- 16-130.htm
