Societa' Italiana Resine S.i.r. S.p.a.

Societa' Italiana Resine S.p.a.

Enzo Chiellini

Luciano Console

Benedetto Calcagno

Ferdinando Bencini

A continuous process for polymerizing acrylonitrile monomer or copolymerizing a mixture of acrylonitrile monomer and a further ethylenically unsaturated monomer copolymerizable therewith in an aqueous medium and in the presence of a catalytic redox system through a primary and a secondary polymerization step. The primary step is carried out in a plurality of independent distinct reaction zones connected in parallel and operated under similar conditions, in which the conversion of the monomer or mixture of monomers is maintained at a value not exceeding 70%. The secondary step is carried out in a single reaction zone connected in series with each of the primary zones. The conversion of the monomer or mixture of monomers in the secondary zone is maintained at a value not exceeding 80% with respect to the overall feed of monomer or mixture of monomers to the primary zones.

Continuous process for the preparation of acrylonitrile polymers and

Sulphur dioxide and unreacted monomer or mixture of monomers are separated and recovered from the polymer or copolymer slurry obtained by polymerizing acrylonitrile monomer or copolymerizing acrylonitrile monomer and a further ethylenically unsaturated monomer copolymerizable therewith in the presence of a catalytic system comprising sulphur dioxide or a sulphite, by a process comprising the steps of separately removing the sulphur dioxide and the monomer or mixture of monomers from the slurry in two distinct volatilization zones connected in series under decreasing subatmospheric pressures, scrubbing with water the sulphur dioxide vapors removed in the first zone and vapors of unreacted monomer or monomers removed in the second zone, and recycling the two resulting aqueous solutions to the polymerization or copolymerization medium.

Separation and recovery of products obtained in catalytic processes of

A copolymer suitable for making self-extinguishing fibers, containing at least 50 wt.% acrylonitrile, from 2 to 30 wt.% vinyl or vinylidene chloride, from 0 to 10 wt.% of a neutral, ethylenically unsaturated, non-halogenated monomer and from 2 to 40 wt.% of alpha-bromoacrylonitrile.

Acrylonitrile copolymers suitable for making flame-resisting fibers

A copolymer suitable for making self-extinguishing fibers, containing at least 50 wt.% acrylonitrile, from 2 to 30 wt.% of vinyl or vinylidene chloride, from 0 to 10 wt.% of a neutral, non-halogenated, ethylenically unsaturated monomer and from 2 to 40 wt.% of a monomer of the general formula: ##EQU1## WHEREIN R is hydrogen or methyl and n is an integer from 1 to 4.

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Rosignano Solvay, Italy

Enzo Chiellini