Isocyanate, Diisocyanate and (Meth) Acrylate Compounds for Minimizing Scorch and Diisocyanate Compounds for Promoting Cure in Crosslinkable Compositions
Thermally activated, free-radical initiator-containing polymer compositions comprise a (i) free radical initiator, (ii) free radical crosslinkable polymer, (iii) scorch inhibiting amount and/or a cure-boosting amount of at least one of isocyanate, diiso-cyanate, e.g., MDI, or hydroxyalkyl(meth)acrylate compound, e.g., hydroxyethyl(meth)acrylate, and, optionally, (iv) other scorch retardants and/or cure boosters, e.g., a TEMPO compound, a hindered phenol, alpha-methyl styrene dimer, etc. The free radical initiator can be any thermally activated compound that is relatively unstable and easily breaks into at least two radicals, e.g., a peroxide or azo initiator. The crosslinkable polymer is a thermoplastic and/or elastomeric polymer that can be crosslinked (cured) through the action of a crosslinking agent, e.g., LDPE. The isocyanate, diisocyanate and (meth)acrylate scorch inhibitors and/or cure boosters can be used alone, or in combination with one another, or, optionally, in combination with a TEMPO compound, e.g., 4-hydroxy-TEMPO.
1 . A polymer composition comprising a (i) free radical initiator, (ii) free radical crosslinkable polymer, and (iii) scorch-inhibiting amount of at least one of an isocyanate, a diisocyanate, and a (meth)acrylate scorch inhibitor, the isocyanate and diisocyanate of formula (I):
R(NCO)n (I)
in which n is at least 1, and R is an aliphatic, alicyclic, aliphatic-alicyclic, aromatic, or aliphatic-aromatic hydrocarbon or an inertly-substituted hydrocarbon radical of 4 to 26 carbon atoms; and the (meth)acrylate scorch inhibitor of formula (II):
CH 2 ═C(R 1 )—C(O)—O—R 2 (II)
in which R 1 is a hydrogen or methyl radical, and R 2 is a straight or branched chain hydrocarbon radical, or a hydroxyalkyl radical, or an inertly-substituted hydrocarbon or hydroxyalkyl radical, having 1 to 10 carbon atoms.
2 . The polymer composition of claim 1 in which the scorch inhibitor is present in an amount of at least 0.01 wt % based on the weight of the polymer.
3 . (canceled)
4 . The polymer composition of claim 2 in which R is C 6-20 and n is 2-4.
5 . The polymer composition of claim 2 in which the scorch inhibitor is at least one of MDI and a polymeric isocyanate.
6 - 9 . (canceled)
10 . The polymer composition of claim 2 in which the (meth)acrylate and diisocyanate scorch inhibitors are present in a molar ratio between 0.1 and 20.
11 . The polymer composition of claim 1 in which the scorch inhibitor further comprises at least one of 4-hydroxy-TEMPO, methyl ether TEMPO, butyl ether TEMPO, hexyl ether TEMPO, allyl ether TEMPO, and stearyl urethane TEMPO.
12 - 24 . (canceled)
25 . A polymer composition comprising a (i) free radical initiator, (ii) free radical crosslinkable polymer, and (iii) cure-boosting amount of a diisocyanate cure booster, the diisocyanate cure booster of formula (I):
R(NCO)n (I)
in which n is at least 2, and R is an aliphatic, alicyclic, aliphatic-alicyclic, aromatic, or aliphatic-aromatic hydrocarbon or an inertly-substituted hydrocarbon radical of 4 to 26 carbon atoms.
26 . The polymer composition of claim 25 in which the cure booster is present in an amount of at least 0.01 wt % based on the weight of the polymer.
27 . (canceled)
28 . The polymer composition of claim 26 in which R is C 6-20 and n is 2-4.
29 . The polymer composition of claim 26 in which the cure booster is at least one of MDI and a polymeric isocyanate.
30 . The polymer composition of claim 25 further comprising a scorch inhibitor.
31 - 32 . (canceled)
33 . The polymer composition of claim 30 in which the scorch inhibitor is at least one of 4-hydroxy-TEMPO, methyl ether TEMPO, butyl ether TEMPO, hexyl ether TEMPO, allyl ether TEMPO, and stearyl urethane TEMPO.
34 - 35 . (canceled)
36 . A method of boosting the cure of a free radical crosslinkable polymer composition comprising a free radical initiator, the method comprising mixing with the composition prior to exposing the composition to free-radical crosslinking conditions a cure-boosting amount of a diisocyanate cure booster, the diisocyanate cure booster of formula (I):
R(NCO)n (I)
in which n is at least 2, and R is an aliphatic, alicyclic, aliphatic-alicyclic, aromatic, or aliphatic-aromatic hydrocarbon or an inertly-substituted hydrocarbon radical of 4 to 26 carbon atoms.
37 . The method of claim 36 in which the cure booster is present in an amount of at least 0.01 wt % based on the weight of the polymer.
38 . (canceled)
39 . The method of claim 37 in which R is C 6-20 and n is 2-4.
40 . The method of claim 37 in which the cure booster is at least one of MDI and a polymeric isocyanate.
41 . The method of claim 37 in which the polymer composition further comprises a scorch inhibitor.
42 - 43 . (canceled)
44 . The method of claim 41 in which the scorch inhibitor is at least one of 4-hydroxy-TEMPO, methyl ether TEMPO, butyl ether TEMPO, hexyl ether TEMPO, allyl ether TEMPO, and stearyl urethane TEMPO.
45 - 46 . (canceled)
47 . An article comprising the polymer composition of claim 1 .
48 . An article comprising the polymer composition of claim 25 .
49 - 52 . (canceled)