Stable antistatic air filter - comprises needled felt made of acrylonitrile! polymer fibres with metal conducting coating

摘要

An anti-static compressed air filter is a needled felt made of acrylonitrile polymer fibres coated with metal for electrical conductivity; the filter is made in conventional manner. Method eliminates problems of separation of metal filaments or of hydrolysis of the organic fibres. In an example, polyacrylic nitrile staple fibres, dtex 7.8/80 mm. were dipped in a bath of HCl (pH is not 1) of colloidal palladium soln. to DT-AS 11 97 720. After stirring between 30 secs. and 2 mins. they are removed and washed with water, then dipped in 5% NaOH at room temp. for 30 secs. - 2 mins., removed and washed with water. They are placed in a solution of 0.2 mol./l. Ni-II-chloride, 0.9 mol./l. NH4OH, 0.2 mol./l. sodium hypophosphite and NH3 is passed in until the pH is 8.9-9.6 at 30 degrees C. Fibres begin to discolour after 15 secs.; after 30 secs. they are coated with fine nickel, after 5 mins. the nickel coating is 0.2um. Fibres are then removed and washed with water. Surface resistivity now 3 x 10 ohms. at 23 degrees C. and 50% R.H. according to DIN 54 345. Volume resistivity is 3 x 102 ohm.cm.2.