Improved method for rendering synthetic linear thermoplastic polymer products infusible

摘要

A method for rendering infusible threads, fibres, films, foils and like products made from linear thermoplastic polymers containing peptide (-CO.NH-) groups, comprises treating the products with a solution of a chromium compound, a solution of tannin, and a solution of tartar emetic (potassium antimonyl tartrate), in any order, and then washing and drying the treated products. Suitable polymers are polyamides, particularly polyhexamethylene adipamide, polyurethanes, polyamide esters, and polymers of e -caprolactam. Suitable chromium compounds are potassium dichromate, chromic sulphate, and chromium acetate. After the treatment with the chromium compound the products may be treated with a reducing agent, such as dilute sodium thiosulphate solution, to reduce any colouration produced. The treating solutions are preferably acidified with formic acid, and each of the treating baths is desirably at a temperature of 60-100 DEG C., preferably 90-95 DEG C. The baths may either be used to exhaustion or be continuously replenished, and the products may be dyed, if desired, either before or after the treatment. The concentration of each bath is generally less than 5 per cent, both of the active solute and of the formic acid, if present.ALSO:In a method for rendering infusible threads, fibres, films, foils and like products made from linear thermoplastic polymers containing peptide (-CO. NH-) groups, wherein the products are treated with a solution of a chromium compound, a solution of tannin, and a solution of tartar emetic (potassium antimonyl tartrate), in any order, and then washed and dried, the products may be dyed either before or after the treatment. Polymers amenable to the process are polyamides, particularly polyhexamethylene adipamide, polyurethanes, polyamide esters, and polymers from e -caprolactam. Suitable chromium compounds with which the polymeric products may be treated are potassium dichromate, chromic sulphate, and chromium acetate. After the treatment with the chromium compound the products may be treated with a reducing agent, such as dilute sodium thiosulphate solution, to reduce any colouration produced. The treating solutions are preferably acidified with formic acid, and the concentration of each bath is generally less than 5 per cent, both of the active solute and of the formic acid, if present. The invention is said to have the advantage that, when mordant dyes are used, a separate chrome treatment, which might otherwise be required, may be dispensed with.