Different properties of the filter cloth can meet the different requirements of various materials filtration. When selecting the filter cloth, in addition to understanding the physical and chemical properties of the material, it is also necessary to know the physical and chemical properties of the filter cloth material and the adaptability of different materials to various materials. In addition, the yarn of the filter cloth must also be considered. The influence of structure, fiber length, weaving method, etc. on the filter performance of the filter cloth. According to the actual use of the filter cloth, the physical properties of the filter cloth can be summarized as follows:
(a) cotton filter cloth
The heat resistance, friction resistance, and tensile strength of the cotton filter cloth are still good; since the fibers are short and the swelling degree is good when wet, the retained particles have good performance. In the presence of hot dilute acids and cold concentrated acids, the wear resistance and tensile strength are reduced; when it is shouted, the wear resistance and tensile strength are also reduced; it is easily corrupted and mildewed; the use temperature does not exceed 100 °C. Because cotton is inexpensive, it is commonly used.
(B) nylon filter cloth
Nylon is also known as nylon, aliphatic polyamide chemical fiber (in which nylon 6 is called polycaprolactam, nylon 66 is called polyhexamethylene adipamide), and its abrasion resistance is root, tensile strength, elongation and elasticity. All are very good, the use of the temperature up to 100 °C resistance is also good, second only to carbon tetrafluoride fiber. But not acid, in the case of concentrated sulfuric acid, concentrated hydrochloric acid will be a chemical reaction and dissolved; easily oxidant oxidation, encountered Oxidation rate is high at high temperature or with high concentration of oxidant: dissolved in organic solvents such as phenols or concentrated formic acid.
(III) Polyester filter cloth
Polyester is a polyester chemical fiber, scientific name is polyethylene terephthalate. Polyester’s tensile strength, abrasion resistance, dimensional stability are very good, especially suitable for drum vacuum filter, horizontal vacuum belt filter filter cloth, belt press filter. Its chemical stability is not good , but resistant to corrosion of oxidizing agents and reducing agents; acid resistance is also better, but not strong sulfuric acid and phosphoric acid; in case of high temperature, high concentration reduction will occur when the chemical reaction to dissolve the polyester; met phenol solvents, with The increase in concentration and temperature is swollen; it will hydrolyze in humid air at high temperatures, so the use temperature is lower than other synthetic fibers, about 80 °C.
(four) polypropylene filter cloth
Polypropylene is a polyolefin chemical fiber, scientific name is polypropylene. Polypropylene’s heat resistance, abrasion resistance and tensile strength are all good. Acid and alkali resistance are the most suitable filter cloths for filtering high-temperature acid and alkaline materials. Due to its poor solubility in organic solvents, it is also commonly used in solvents and paints. Filtration of dyes, mineral oils, etc.: Use temperatures up to 90°C.
(v) Vinylon filter cloth
Vinyl is a polyvinyl alcohol chemical fiber, scientific name is polyvinyl formal. Vinylon’s tensile strength and wear resistance are good: alkali resistance is also very good; case of concentrated sulfuric acid, concentrated hydrochloric acid was swollen or decomposition; insoluble in animal oils, vegetable oils and mineral oil; when hot pyridine, benzene powder was swollen Or decomposition. Use temperature up to 100°C.
(6) Cotton, Wool and Rayon Filter Cloth
Wool filter cloth has slightly better acid resistance than cotton filter cloth, and can be filtered by dry, thin, acidic suspension or highly viscous suspension; it is not alkali-resistant and easy to clog. Rayon filter cloths have poorer tensile and abrasion resistance than cotton filter cloths, and their alkali resistance is inferior to cotton filter cloths. However, other chemical characteristics are similar to those of cotton filter cloths and can be used for press filtration with coarse particle suspensions.
(7) Nonwoven filter cloth
The tensile and abrasion resistance of nonwoven filter cloths is inferior to that of filter cloths that are strong with the same fibers. Non-woven filter cloth is deep filtration, and has good effect on particle retention, so it is widely used. Wool and synthetic fiber felts are commonly used in the filtration of pharmaceuticals, coatings, essential oils, foods, beverages, dyes, etc. Non-woven filter cloths are commonly used in various chemical industries, especially for highly viscous liquids, cooling oils, vegetable oils, and beverages filter.