| 摘要 |
A process for improving the thermal stability of a solid oxymethylene polymer containing in the polymer molecule oxyalkylene units having two or more adjacent carbon atoms comprises heating the polymer under non-acidic conditions with water, an organic hydroxy compound or a mixture thereof to remove formaldehyde or its elements from the polymer until the polymer weight loss per minute falls below 5% of the weight loss during the first minute of heating. Exemplified polymers are copolymers of trioxane with dioxolane and ethylene oxide. Exemplified hydroxy compounds are methanol, isopropyl alcohol and triethanolamine. The reaction preferably takes place in solution in any of the well-known water/solvent systems. The compounds ensuring the non-acidity of the medium exemplified are ammonia, tripropylamine, tetramethyl guanidine, sodium acetate and/or one of the alcohols mentioned above. Specifications 903,668 and 964,004 are referred to. |
