Polyamide mol.wt. increase by after-processing for injection moulding - by reaction in melt with modified polyamide contg. grafted ester gps. based on carboxylic acid and tert. alcohol, for fibres and film

摘要

The prodn. comprises reaction with a thermoplastic (II) in the melt, opt. with addn. of other substances. (II) is a modified polyamide grafted with 2-20 wt.% ester gps. derived from carboxylic acids (III) and tert. alcohols (IV). The unmodified polyamide (PA) is pref. PA 6 with relative soln. viscosity (R.V.) below 3.6. (II) is a PA grafted with tert.-butyl (meth)acrylate (TBA or TBMA); and pref., (II) contains 2-20 wt.% side chains based on ester monomers as above, grafted on a PA with m.pt. below 180 deg. C, esp. PA6,24. PA 6,36 or PA 6,44. Reaction is pref. in the melt at 220-290 deg. C in an extruder. Other additives are 0.5-8 wt% polyethylene- or polypropylene-oxide of mol. wt. 500-50,000, 0.2-20 wt.% (partly) hydrolysed EVA copolymer (10-40 wt.% vinyl acetate) or 5-20 wt.% elastomer, esp. acid-modified EP rubber or acid-modified styrene-ethylene -butadiene-styrene block copolymer. USE/ADVANTAGE - Used for the prodn. of fibres, film, injection mouldings, hollow and semi-finished prods. The prodn. enables the mol. wt. of polyamides to be increased by post-condensn., with the aid of an additive which is compatible with the polyamide (c.f. prior-art polyfunctional additives e.g. bislactams, diaryl or carbonate esters, etc., and maleic anhydride copolymers, which may result in lack of homogeneity in the final prod.).