Polyacetal resin composition with good long-term high temperature thermal stability

摘要

Polyacetal resin composition contains 100 parts weight polyacetal with a residual fluorine (F) concentration /} 13 ppm and a formaldehyde (HCHO) concentration, produced by heating for 30 minutes at 230 deg C in nitrogen (N2) /} 500 ppm, 0.01-3 parts weight antioxidant and 0.001-5 parts weight basic substance. Preferably the residual F concentration is /} 8 ppm and HCHO concentration /} 300 ppm. The polyacetal is obtained by polymerisation of trioxane and optionally a comonomers in the presence of boron trifluoride (BF3), BF3 trihydrate and/or co-ordination complex of an organic compound containing an oxygen or sulphur atom with BF3 as catalyst. Sterically hindered phenol and/or amine compound(s) are used. The base is selected from compounds containing nitrogen, hydroxides and alkali(ne earth) salts of inorganic or carboxylic acids.