Process for the bulk-polymerization of acrylonitrile

Claim 2

IN A PROCESS FOR THE BULK POLYMERIZATION OF ACRYLONITRILE OR A MIXTURE OF ACRYLONITRILE WITH UP TO ABOUT 50 MOL PERCENT OF AT LEAST ONE OTHER ETHYLENICALLY UNSATURATED MONOMER COPOLYMERIZABLE THEREWITH, WHICH COMPRISES CARRYING OUT THE POLYMERIZATION USING: A. A CONTINUOUS OR SEMI-CONTINUOUS POLYMERIZAION PROCEDURE, B. A FREE-RADICAL CATALYST SYSTEM HAVING A DECOMPOSITION RATE CONSTANT (KD) GREATER THAN 1 HR.-1 AND SELECTED FROM THE GROUP CONSISTING OF: (1) AN ORGANIC HYDROPEROXIDE, AN OXIDIZABLE SULPHOXY COMPOUND, OR SULPHUR DIOXIDE AND A NUCLEOPHILIC COMPOUND; (2) AN ORGANIC HYDROPEROXIDE AND A MONOESTER OF SULPHUROUS ACID; AND (3) AN ORGANIC HYDROPEROXIDE, A MAGNESIUM ALCOHOLATE AND A DIALKYL SULPHITE; C. A RESIDENCE TIME (Q) AT LEAST SUFFICIENT TO HALF-DECOMPOSE THE CATALYST, AND D. A CATALYST CONCENTRATION AT LEAST EQUAL TO 2 X 10**-3 X Q MOLES/LITER, WHEREIN (Q) IS THE RESIDENCE TIME IN HOURS; AN IMPROVEMENT ACCORDING TO WHICH THE POLYMERIZATION IS CARRIED OUT IN THE CO-PRESENCE OF NOT MORE THAN 3,000 PPM, BASED ON THE WEIGHT OF THE MONOMERS, OF A MERCAPTO COMPOUND HAVING THE GENERAL FORMULA:

Claim 3

In a process for the bulk polymerization of acrylonitrile or a mixture of acrylonitrile with up to about 50 mol percent of at least one other ethylenically unsaturated monomer copolymerizable therewith, which comprises carrying out the polymerization using: a. a continuous or semi-continuous polymerization procedure, b. a free-radical catalyst system having a decomposition rate constant (Kd) greater than 1 hr. 1 and selected from the group consisting of: (1) an organic hydroperoxide, an oxidizable sulphoxy compound, or sulphur dioxide and a nucleophilic compound; (2) an organic hydroperoxide and a monoester of sulphurous acid; and (3) an organic hydroperoxide, a magnesium alcoholate and a dialkyl sulphite; c. a residence time (Q) at least sufficient to half-decompose the catalyst, and d. a catalyst concentration at least equal to 2 X 10 3 X Q moles/liter, wherein (Q) is the residence time in hours; an improvement according to which the polymerization is carried out in the co-presence of not more than 3,000 ppm, based on the weight of the monomers, of a mercapto compound having the general formula: R4-SH wherein R4 is a linear or branched chain aliphatic radical having from 1 to 20 carbon atoms and optionally containing in the chain, an -OH or -SH group, and not more than 2 percent by weight, based on the weight of the monomers, of a basic nitrogen containing compound selected from the group consisting of an amide of the formula:

Claim 4

In a process for the bulk polymerization of acrylonitrile or a mixture of acrylonitrile with up to about 50 mol percent of at least one other ethylenically unsaturated monomer copolymerizable therewith, which comprises carrying out the polymerization using: a. a continuous or semi-continuous polymerization procedure, b. a free-radical catalyst system having a decomposition rate constant (Kd) greater than 1 hr. 1 and selected from the group consisting of: (1) an organic hydroperoxide, an oxidizable sulphoxy compound, or sulphur dioxide and a nucleophilic compound; (2) an organic hydroperoxide and a monoester of sulphurous acid; and (3) an organic hydroperoxide, a magnesium alcoholate and a dialkyl sulphite; c. a residence time (Q) at least sufficient to half-decompose the catalyst, and d. a catalyst concentration at least equal to 2 X 10 3 X Q moles/liter, wherein (Q) is the residence time in hours; an improvement according to which the polymerization is carried out in the co-presence of not more than 3,000 ppm, based on the weight of the monomers, of a mercapto compound having the general formula: R4-SH wherein R4 is a linear or branched chain aliphatic radical having from 1 to 20 carbon atoms and optionally containing in the chain, an -OH or -SH group, and not more than 2 percent by weight, based on the weight of the monomers, of a basic nitrogen containing compound selected from the group consisting of an amide of the formula:

Claim 5

A process according to claim 1, wherein R4 is an alkyl radical having from 2 to 12 carbon atoms.

Claim 6

A process according to claim 1, wherein the basic nitrogen containing compound is dimethylformamide or dimethylacetamide.

Claim 7

A process according to claim 1, wherein the amount of the basic nitrogen containing compound is between 0.1 and 1 percent by weight.