Ethylene-acrylic ester copolymers with improved optical properties - by copolymerisation in presence of radical initiators, with simultaneous, but separate addn. of initiator and ester-stabiliser mixt.

摘要

Copolymers (I) of ethylene- and alkene-carboxylic acid esters (II) with improved optical properties are obtd. by reaction of ethylene and (II) at 10-800 MPa and 110-350 deg.C in the presence of radical initiators and opt. a moderator. The novelty is that a stabiliser (III) is added to (II), and the stabilised (II) and the initiator (IV) are added to the reaction mixt. simultaneously but separately from one another. (II) is an ester of a 3-12C (pref. 3-8C, esp. 3-6C) alkene carboxylic acid and a 1-16C (pref. 1-12C, esp. 1-8C) aliphatic alcohol. (III) is a deriv. of a phenol, an amine, or an organic S or P cpd., pref. 4-methoxyphenol (IIIA), 2,6-tert.-butyl-4- methylphenol, pentaerythrityl tetrakis-(3-(3,5-di-tert.-butyl -4-hydroxphenyl)-propionate) (IIIB), octadecyl-(3-(3,5-di-tert. -butyl-4-hydroxyphenyl)- propionate) (IIIC), 4,4'-thiobis-(3- methyl-6-tert.-butylphenol) or tri-(3,4-di-tert.-butylphenyl)- phosphite, esp. (IIIA), (IIIB) or (IIIC). Amt. of (III) is 1000-20,000 (pref. 1250-12,000, esp. 2000-10,000) wt. ppm w.r.t. (II). (IV) is oxygen, an organic peroxide or hydroperoxide (pref. di-tert.-butyl or dilauryl peroxide, tert.-butyl perbenzoate or perpivalate, or tert.-butyl or p-menthane hydroperoxide), or an azo cpd. (pref. AIBN), in amts. of 25-300 (pref. 30-250, esp. 40-200) wt. ppm w.r.t. total monomers; (II) are (meth)acrylate esters, pref. methyl, ethyl, n-butyl, iso-butyl or 2-ethylhexyl (meth)acrylate, glycidyl acrylate or stearyl acrylate, in amts. of 0.3-10wt.% w.r.t. ethylene. USE/ADVANTAGE - (I) are useful for the prodn. of films, cable sheathing, coatings and modified polymers (claimed). The process enables the prodn. of (I) with improved optical properties, esp. low haze and high glos