Compositions based on thermoplastic polymers and metal carboxylate silanol condensation catalysts

DETAILED DESCRIPTION OF THE INVENTION The present invention provides water-curable compositions which are characterized by relatively fast cure rates, in the absence of organo titanates.
A composition of this type comprises a water curable thermoplastic polymer having hydrolyzable pendant silane moieties, a metal carboxylate, as the sole silanol condensation catalyst, in an amount of about 0.
01 to 0.
5 percent by weight based on the weight of the polymer and a monomeric, hydrolytically reactive silane in an amount of about 0.
05 to 5 percent by weight based on the weight of the composition, said silane added immediately prior to or concurrently with said carboxylate.
Consequently, the compositions are particularly attractive from a commercial standpoint as they can be water-cured quickly, without the necessity of adding thereto relatively expensive and sometimes unavailable organo titanates, to crosslinked products characterized by an excellent balance of commercially acceptable properties, including an acceptable solvent extractables level, a percent crosslinking of at least about 50 percent and a rheometer reading after immersion in 70.
degree.
C.
water for 16 hours, conditions under which polymers are crosslinked commercially, of at least about 20 lbs-inch.
As to tests conducted to determine the "potential" of water-curable polymers, Monsanto Rheometer test is a laboratory diagnostic test capable of rapidly measuring the degree of crosslinking in polymers by a high temperature viscosity measurement.
In commercial practice, however, the degree of crosslinking is measured by determining the amount of material that can be extracted by subjecting the crosslinked polymer to a hot solvent.
High levels of extractables indicate a low level of crosslinking and vice-versa.
Standards of degree of crosslinking have been set for specific polymers to be used in specific applications.
For example, one widely used set of specifications for crosslinked ethylene polymers to be used as insulation material in wire and cable applications is the Insulated Cable Engineers Association and National Electrical Manufacturers Association (ICEA/NEMA) Standards Publications ICEA No