Yeda Research and Develpment & Co. Ltd

The Weizmann Institute of Science

Gideon Levin

Hemi N Nae

David Vofsi

Lev Bromberg

Gelled material compositions with modified halopolymer

Crosslinked plasticized or unplasticized PVC products having gradient crosslinking density, with a high crosslinking density on the outer surface and a low or none crosslinking density at the bulk of the product, are prepared by immersing the PVC product in a hot water solution of a crosslinking material and a phase transfer catalyst. The products obtained provide controlled release of substances occluded within the PVC matrix, thus preventing leakage of plasticizers, stabilizers and other additives, and permitting controlled slow release of substances like pesticides, fertilizers, drugs and the like, into the surrounding environment.

Stabilized PVC products and their production

To plasticized polyvinyl chloride (PVC) there is applied a layer of PVC modified by the introduction of functional groups which can be crosslinked, preferably under the influence of heat. Such crosslinking provides a thin coating which prevents leakage of plasticizer and additives from the plasticized PVC substrate when it is contacted with solvents. Preferred modification of the PVC is by means of thiocarbamate moieties replacing some of the chlorine in the PVC from which the surface layer is produced.

Prevention of plasticizer migration from PVC products

There are provided polymers containing amido-thiolate groups. These are produced by a nuceophilic substitution of polymers containing chlorine, and the resulting polymers have a pronounced hydrophylic character. There is also provided a process for the production of these starting with polymers which contain chlorine in the polymeric backbone or in side chains.

Nucleophilic substitution of chlorine containing polymers in aqueous

There are provided polymers containing chlorine wherein part of the chlorine atoms are substituted by thio-amide groups and where a further part of the chlorine atoms are substituted by epoxy moieties. Starting materials of choice are chlorinated polyalkylenes, polyvinyl chloride and polyvinylidene chloride. The polymers are produced by first producing a chlorine containing polymer wherein part of the chlorine is substituted by thio-amide groups, and further reacting such product with an epoxy resin so as to introduce epoxy groups.

Grafting of epoxy resin on amide

The present invention relates to modified polyvinylchloride, wherein part of the chlorine atoms are replaced by groups of the formula --S--CH.sub.2 --CH.sub.2 --R--(CH.sub.2 --CH.sub.2 --R).sub.n --Alk, wherein R is selected from oxygen, sulfur and --NH--, where R may also designate a bond, where Alk designates an alkyl group of up to 14 carbon atoms, and where n is zero or an integer of from 1 to 100, and to a process for the production of such modified polyvinylchloride polymers which comprises reacting an aqueous emulsion or suspension of polyvinylchloride in the presence of a solvent adapted to cause swelling of the PVC particles with a compound of the formula Alk--(CH.sub.2 --CH.sub.2 --R).sub.n --R--CH.sub.2 --CH.sub.2 --SH, wherein Alk, R and n are as defined above.

Growing community of inventors

Rehovot, Israel

Gideon Levin