Kenogard Ab

Akzo Nobel N.v.

Berol Nobel Ab

Berol Nobel Nacka Ab

Claes O Lundin

Berit Simonsson

Berit I Simonsson

Bjorn J Akermark

Erik M Larsson

A process for the preparation of an aqueous suspension of a solid free-radical forming initiator, a plant for the preparation, an initiator suspension and use of the suspension in polymerization of ethylenically unsaturated monomers. The process for the preparation of the suspension comprises the steps of:

Initiator suspensions, their preparation and use

An initiator suspension for use in the suspension polymerization of ethylenically unsaturated monomers is prepared by (a) heating the initiator to its melting point; (b) finely dividing the initiator in water while it is in a molten state; and (c) rapidly cooling so that the initiator is in a molten state for a period of time which is less than about 5 minutes. The initiator suspension has very small particles and a narrow particle size distribution whereby at least 50% by weight of the particles are smaller than 5 .mu.m and at least 90% by weight of the particles are smaller than 10 .mu.m.

Initiator suspension, their preparation and use

New dialkyl esters of monoperoxyoxalic acid which have a tertiary alkyl group in the perester part of the molecule while the other alkyl group is a long-chain, primary alkyl group. The compounds give rise to radicals at heating and are useful as initiators for the polymerization of ethylenically unsaturated monomers, particularly for the polymerization of vinyl chloride.

Ester of monoperoxy oxalic acid as polymerization initiators

Peresters, their preparation and use as polymerization initiators

A process for the polymerization of ethylenically unsaturated monomers, such as vinyl chloride, wherein a solid, monomer-soluble, free-radical forming compound is used as initiator. The initiator is added to the polymerization system in the form of an aqueous dispersion which contains an ethoxylated nonionic emulsifier with an HLB-value above 15, and preferably above 17, which emulsifier does not contain cyclic inner ether bonds. Polymerizates produced according to the method have good electric insulation properties. Suitable ethoxylated nonionic emulsifiers are ethoxylated fatty acids and ethoxylated fatty alcohols. A means, suitable for polymerization of ethylenically unsaturated monomers, consists of an aqueous dispersion of a free-radical forming compound containing a nonionic ethoxylated emulsifier with an HLB-value above 15, in an amount of at least 1 percent by weight, based on the initiator, and preferably also a protective colloid such as polyvinyl alcohol. The dispersions have good stability and are easy to handle.

Process for the polymerization of ethylenically unsaturated monomers

A process for the polymerization of ethylenically unsaturated monomers wherein a solid, monomer-soluble, free-radical forming compound is used as initiator. The initiator is charged to the polymerization system in the form of an aqueous dispersion comprising an emulsifier combination which consists of an ethoxylated nonionic emulsifier with an HLB-value above 15, which does not contain cyclic inner ether bonds, and a non-ethoxylated nonionic emulsifier with an HLB-value below 9. The emulsifier combination has a resulting HLB-value within the interval 11-17 and the combination is used in an amount of at least 1% by weight based on the initiator. Polymerizates produced according to the method have good electric insulation properties. A means suitable for the polymerization of ethylenically unsaturated monomers consists of an aqueous dispersion of a free-radical forming initiator, which dispersion comprises the mentioned emulsifier combination in an amount of at least 1 percent by weight, based on the initiator. The dispersion preferably also contains a protrective colloid such as polyvinyl alcohol. The dispersions have good stability and are easy to handle.

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Saltsjo-Boo, Sweden

Claes O Lundin