Stabilized PVC products and their production
First Claim
1. A crosslinked PVC product characterized by a gradient crosslinking density, with a high crosslinking density on the outer surface and/or near the surface and a low or none crosslinking density at the bulk of the product.
1 Assignment
0 Petitions
Accused Products
Abstract
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.
15 Citations
24 Claims
- 1. A crosslinked PVC product characterized by a gradient crosslinking density, with a high crosslinking density on the outer surface and/or near the surface and a low or none crosslinking density at the bulk of the product.
-
3. A process for the preparation of a PVC product having a crosslinked outer surface characterized by a gradient crosslinking density, with a high crosslinking density on said outer surface and a lower or no crosslinking density within the bulk of the product, the process comprising
immersing an un-crosslinked PVC product in a water solution of a water-soluble crosslinking material and a phase transfer catalyst, at a temperature of at least about 60° - C., said crosslinking material being capable of reacting with chlorine containing polymers by displacing the chlorine and then further reacting with a second chlorine to form a crosslinking network, said crosslinking material being present in an amount sufficient to be capable of diffusing into the PVC product so as to displace at least one chlorine atom along polymeric chains of said PVC to provide substituted polymer molecules, and
maintaining said PVC product within said water solution at said temperature for a time sufficient to effect diffusion of said crosslinking material and said phase transfer catalyst into the PVC product so as to effect displacement of at least one chlorine atom along polymeric chains of said PVC to provide substituted polymer molecules, and triggering a chemical crosslinking of said substituted polymer molecules to produce a crosslinked outer surface characterized by a gradient crosslinking density with a high crosslinking density on said outer surface and a low or no crosslinking density within the bulk of the PVC product. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
- C., said crosslinking material being capable of reacting with chlorine containing polymers by displacing the chlorine and then further reacting with a second chlorine to form a crosslinking network, said crosslinking material being present in an amount sufficient to be capable of diffusing into the PVC product so as to displace at least one chlorine atom along polymeric chains of said PVC to provide substituted polymer molecules, and
-
24. A process for the preparation of a PVC product having a crosslinked outer surface characterized by a gradient crosslinking density, with a high crosslinking density on said outer surface and a low or no crosslinking density within the bulk of the product, the process comprising
immersing an un-crosslinked PVC product in a water solution at said temperature of a water-soluble crosslinking material and a phase transfer catalyst, at a temperature of at least about 60° - C., said crosslinking material being capable of reacting with chlorine containing polymers by displacing the chlorine and then further reacting with a second chlorine to form a crosslinking network.
maintaining said PVC product within said water solution for a time sufficient to effect diffusion of said crosslinking material and said phase transfer catalyst into the PVC product so as to effect displacement of at least one chlorine atom along polymeric chains of said PVC to provide substituted polymer molecules, and triggering a chemical crosslinking of said substituted polymer molecules, wherein the crosslinked PVC product is further treated with a water solution of an inorganic or organic salt having a cation selected form the group consisting of an alkali, earth alkali and a tradition metal residue and an anion selected from the group consisting of NO3 -, SO4-2, PO4-3 and CF3 COO.
- C., said crosslinking material being capable of reacting with chlorine containing polymers by displacing the chlorine and then further reacting with a second chlorine to form a crosslinking network.
Specification