In-situ methods of generating water through the dehydration of metal salt hydrates for moisture crosslinking of polyolefins
View Patent ↗Compositions comprising a polymer resin comprising at least one copolymer with hydrolyzable groups, a water-generating metal salt hydrate, and a catalyst that comprises a metal atom and at least two ligands taken from the set alkyloxy and carboxylate are used to form articles that moisture-cure through in-situ generation of water via dehydration of the metal hydrate. The compositions are melt mixed to promote the dehydration and start the cure process during the mixing step. The curing compositions are formed and allowed to harden.
1. A composition comprising:
(A) A copolymer of ethylene and a vinyltrialkoxysilane in which the alkoxy group is RO and R is an alkyl group of 1 to 8 carbon atoms,
(B) A hydrated salt of the general formula M x Q y (H 2 O) z , wherein M is a cation of a metal selected from groups 1 through 13 of the periodic table, Q is an anion formed from the deprotonation of a carboxylic acid, x and y are integers taken to balance the overall charge of the salt, and z is the hydration number of the salt on a molar basis at 25° C., and the hydrated salt having an onset temperature of dehydration of greater than 100° C. and less than 200° C.; and
(C) A catalyst that comprises a metal ion and at least two ligands taken from the set alkoxide and carboxylate.
2. The composition of claim 1 wherein the copolymer is a copolymer of ethylene and vinyltrimethoxysilane.
3. The composition of claim 1 wherein vinyltrialkoxysilane is present in an amount between about 0.1 and about 5 mole % relative to all monomers.
4. The composition of claim 1 wherein the hydrated salt is a tartrate, citrate or acetate.
5. The composition of claim 4 wherein the wherein the hydrated salt is at least one of sodium L-tartrate dihydrate, sodium citrate tribasic dihydrate, or sodium acetate trihydrate.
6. The composition of claim 1 wherein the hydrated salt is present in an amount sufficient to provide between about 0.1 and about 4 moles of water per mole of hydrolyzable groups.
7. The composition of claim 1 wherein the catalyst is present in an amount between about 0.1 and about 20 mole % based on the moles of hydrolyzable groups.
8. A composition comprising the composition of claim 1 and at least one non-moisture curable polymer resin.
9. A composition comprising the composition of claim 1 and at least one of flame retardants, fillers, antioxidants, phosphites, UV stabilizers, cling additives, light stabilizers, thermal stabilizers, mold release agents, tackifiers, waxes, processing aids, crosslinking agents, colorants or pigments.