Ambient-curable resin formulations
Disclosed herein are ambient curable resin formulations comprising moisture scavenging, non-grafting silanes that improve the processability of the resin. Cable manufacturing methods comprising extrusion of the resin formulations are also disclosed herein, as advantageously allowing acceptable levels of cross-linking without requirement of conventional vulcanization and moisture cure processes. Resulting cables having a jacket with a reduced amount of scorch, and acceptably cross-linked jacket are also disclosed.
1 . A crosslinkable, fire retardant formulation comprising:
a polymer component comprising a silane graftable polymer, a silane grafted polymer, or both;
from 30 wt. % to 70 wt. % of a fire retardant;
from 0.5 wt. % to 5 wt. % of a non-grafting silane, the non-grafting silane comprising a hydrolyzable substituent and an unreactive substituent; and
an ambient-cure catalyst;
wherein a total amount of hydrolyzable substituents of the non-grafting silane is in a range from 0.12 to 0.25 mmol per gram of the fire retardant formulation, and wherein a total amount of hydrolysable substituents of the non-grafting silane is in a range from 0.55 to 0.75 mmol per gram of the fire retardant.
2 . The formulation of claim 1 , wherein the polymer component comprises a silane graftable polymer, and further comprises a grafting silane.
3 . The formulation of claim 2 , wherein the grafting silane is vinyl trimethoxysilane or vinyl triethoxysilane.
4 . The formulation of claim 2 , further comprising a radical initiator to initiate a grafting reaction between the grafting silane and the silane graftable polymer.
5 . The formulation of claim 4 , wherein the radical initiator is dicumyl peroxide.
6 . The formulation of claim 1 , wherein the polymer component comprises an ethyl vinyl acetate copolymer.
7 . The formulation of claim 1 , wherein the fire retardant is selected from aluminum trihydrate, magnesium dihydrate, rare earth hydrate, or a combination thereof.
8 . The formulation of claim 1 , wherein the non-grafting silane is selected from an alkoxysilane, an acetoxysilane, a ketoximinosilane, or combinations thereof.
9 . The formulation of claim 8 , wherein the non-grafting silane is a polymeric tetraalkyl orthosilicate, a C 1 -C 30 alkyl trimethoxysilane, or a C 1 -C 30 alkyl triethoxysilane.
10 . The formulation of claim 9 , wherein the non-grafting silane is n-octyl triethoxysilane.
11 . The formulation of claim 1 , wherein the amount of non-grafting silane is in a range from 5 phr to 15 phr.
12 . The formulation of claim 1 , wherein the ambient-cure catalyst is dibutyltin dilaurate.
13 . The formulation of claim 1 , wherein the composition further comprises a processing aid, coupling agent, antioxidant, filler, or any combination thereof.
14 . A cross-linked polymeric composition comprising the formulation of claim 1 , or the extruded product thereof.
15 . An article comprising the cross-linked composition of claim 14 .
16 . The article of claim 15 , wherein the article is a fire retardant cable.
17 . A method for producing a crosslinked polymeric composition, the method comprising:
grafting a silane to a polymer;
compounding the polymer with:
a fire retardant in an amount from 30 wt. % to 70 wt. %, based on the total weight of the cross-linked polymeric composition;
a non-grafting silane comprising a hydrolyzable substituent, wherein a total amount of the hydrolyzable substituent is in a range from 0.12 to 0.25 mmol per gram of the cross-linked polymeric composition and wherein a total amount of hydrolysable substituents of the non-grafting silane is in a range from 0.55 to 0.75 mmol per gram of the fire retardant, the non-grafting silane further comprising an unreactive substituent; and
an ambient-cure catalyst;
extruding the polymeric resin onto an article; and
curing the polymeric resin under ambient conditions.
18 . The method of claim 17 , wherein compounding the polymer is conducted as a single step within a twin screw extruder.
19 . The method of claim 18 , wherein grafting the silane to a polymer is conducted simultaneously with compounding the polymer.