In situ moisture generation and use of polyfunctional alcohols for crosslinking of silane-functionalized resins
View Patent ↗Polymer compositions comprise a (i) silane-functionalized polymer, e.g., a polyethylene grafted with vinyl triethoxy silane, (H) polyfunctional alcohol e.g., α,α,α′,α′˜tetramethyl-I,3-benzenediethanol and, optionally, (iii) acid, e.g., an alkylated aryl disulfonic acid. The use of polyfunctional alcohols in the absence of a strong acid yields a light-crosslinking of the silane-functionalized polymer and this, in turn, provides a polymer melt with improved extensional properties such as elongational viscosity and melt strength. The use of a polyfunctional alcohol in combination with a blocked strong acid provides a slow rate of crosslinking during melt processing and a high degree of ultimate crosslinking after the polymer composition has been shaped or molded.
1. A polymer composition comprising:
(i) A silane-functionalized polyolefin,
(ii) A polyfunctional alcohol wherein the polyfunctional alcohol is α,α,α′,α′-tetramethyl-1,3-benzenedimethanol and,
(iii) A blocked, strong acid,
the composition characterized in that the dehydration of the alcohol accelerates moisture-induced crosslinking of the composition at a temperature from 120° C. to 200° C. relative to a composition comprising only the silane-functionalized polyolefin and the blocked, strong acid and having the same weight percentage of the blocked, strong acid.
2. The composition of claim 1 wherein the silane-functionalized polyolefin is a copolymer of ethylene and vinyl trialkoxy silane monomers.
3. The composition of claim 1 wherein the blocked strong acid is an alkylated aryl disulfonic acid.
4. The composition of claim 3 wherein the alkylated aryl disulfonic acid has one of the following structures:
wherein each of R 1 and R 2 is the same or different and is a linear or branched alkyl group with 6 to 16 carbons, y is 0 to 3, z is 0 to 3 with the proviso that y +z is 1 to 4, n is 0 to 3, X is a divalent moiety selected from the group consisting of —C(R 3 )(R 4 )—, wherein each of R 3 and R 4 is hydrogen or independently a linear or branched alkyl group of 1-4 carbons and n is 1; —C(═O)—, wherein n is 1; —O— wherein n is 1 to 3; and —S(O) 2 —, wherein n is 1.
5. The composition of claim 1 wherein the polyfunctional alcohol is present in an amount ranging from about 0.01 to about 5 wt %, based on the total weight of the composition.
6. The composition of claim 1 wherein the acid is present in an amount ranging from about 0.01 to about 5 wt %, based on the total weight of the composition.
7. A fabricated article comprising the polymer composition of claim 1 .
8. The article of claim 7 in which the article is a cable sheath or cable jacket.
9. The article of claim 7 in which the article is a fiber, ribbon, sheet, tape, tube, pipe, weather-stripping, seal, gasket, foam, footwear or bellows.