Silane-crosslinkable, substantially linear ethylene polymers and their uses

Claim 2

A curable, substantially linear ethylene polymer grafted with a silane crosslinker, the polymer, prior to being grafted with the silane, characterized as having: (i) a melt flow ratio of I 10 /I 12 ≧5.63; (ii) a molecular weight distribution, M w /M n , defined by the equation: M.sub.w /M.sub.n ≦(I.sub.10 /I.sub.2)-4.63; (iii) a density between about 0.850 and 0.91 g/cm 3 ; (iv) a critical shear rate at onset of surface melt fracture of at least 50 percent greater at the onset of surface melt fracture of a linear olefin polymer having about the same I 2 and M w /M n ; and (v) a melt index of between 1 and 200 g/10 min.

Claim 3

The grafted polymer of claim 1 in which the silane crosslinker is ##STR2## in which R' is a hydrogen atom or methyl group; x and y are 0 or 1 with the proviso that when x is 1, y is 1; n is an integer from 1 to 12 inclusive, and each R independently is selected from the group consisting of C 1 -C 12 alkoxy, C 1 -C 12 aryloxy, C 1 -C 12 araloxy, C 1 -C 12 aliphatic acyloxy, amino or substituted amino groups, and a C 1 -C 6 alkyl, with the proviso that not more than one of the three R groups is an alkyl.

Claim 4

The grafted polymer of claim 2 in which the silane crosslinker is present in amount between 0.5 to 5 parts per hundred ethylene polymer.

Claim 5

The grafted polymer of claim 3 in which the ethylene polymer is a copolymer of ethylene and at least one α-olefin of 3 to 20 carbon atoms.

Claim 6

The grafted copolymer of any of the claims 1-4 after at least a partial cure.

Claim 7

The grafted polymer of claim 1 or 2 in combination with a filler.

Claim 8

A process for making a curable, substantially linear ethylene polymer grafted with a silane crosslinker, the ethylene polymer characterized as having: (i) a melt flow ratio of I 10 /I 2 ≧5.63; (ii) a molecular weight distribution, M w /M n , defined by the equation: M.sub.w /M.sub.n ≦(I.sub.10 /I.sub.2)-4.63; (iii) a density between than 0.850 and 0.91 g/cm 3 ; (iv) a critical shear rate at onset of surface melt fracture of at least 50 percent greater at the onset of surface melt fracture of a linear olefin polymer having about the same I 2 and M w /M n ; and (v) a melt index of between 1 and 200 g/10 min; the process comprising the steps of: A. preparing a melt of the polymer; B. mixing into the melt of (A) at ambient temperature, between about 0.5 and about 5 parts per hundred resin of a silane crosslinker; and C. subjecting the melt of (B) to ionizing radiation or contacting the melt of (B) with a free radical initiator such that at least about 50 wt percent of the silane crosslinker grafts to the copolymer.

Claim 9

A process for making a curable, substantially linear ethylene polymer grafted with a silane crosslinker, the ethylene polymer characterized as having: (i) a melt flow ratio of I 10 /I 2 ≧5.63; (ii) a molecular weight distribution, M w /M n , defined by the equation: M.sub.w /M.sub.n ≦(I.sub.10 /I.sub.2)-4.63; (iii) a density between than 0.850 and 0.91 g/cm 3 ; (iv) a critical shear rate at onset of surface melt fracture of at least 50 percent greater at the onset of surface melt fracture of a linear olefin polymer having about the same I 2 and M w /M n ; and (v) a melt index of between 1 and 200 g/10 min; the process comprising the steps of: A. preparing a melt of the polymer; B. mixing into the melt of (A) at ambient temperature, between about 0.5 and about 5 parts per hundred resin of a silane crosslinker; and C. subjecting the melt of (B) to ionizing radiation or contacting the melt of (B) with a free radical initiator such that at least about 50 wt percent of the silane crosslinker grafts to the copolymer.

Claim 10

The process of claim 7 comprising the further step (D) mixing into the melt of (C) between 0.015 and 0.035, phr of a crosslinking catalyst.

Claim 11

A process for making an insulated cable, the process comprising the steps of: A. Preparing a melt of a substantially linear ethylene polymer characterized as having: (i) a melt flow ratio of I 10 /I 2 ≧5.63; (ii) a molecular weight distribution, M w /M n , defined by the equation: M.sub.w /M.sub.n ≦(I.sub.10 /I.sub.2)-4.63; (iii) a density between than 0.850 and 0.91 g/cm 3 ; (iv) a critical shear rate at onset of surface melt fracture of at least 50 percent greater than the critical shear rate at the onset of surface melt fracture of a linear olefin polymer having about the same I 2 and M w /M n ; and (v) a melt index of between 1 and 200 g/10 min; B. Mixing into the melt of (A) at ambient temperature, between about 0.5 and about 5 parts per hundred resin of a silane crosslinker; C. Subjecting the melt of (B) to ionizing radiation or contacting the melt of (B) with a free radical initiator such that at least about 50 wt % of the silane cross linker graphs to the polymer of the melt of (A); D. Extruding the melt of (C) over a cable; and, optionally, E. Curing the melt extruded over the cable.

Claim 12

A process for making an insulated cable, the process comprising the steps of: A. Preparing a melt of a substantially linear ethylene polymer characterized as having: (i) a melt flow ratio of I 10 /I 2 ≧5.63; (ii) a molecular weight distribution, M w /M n , defined by the equation: M.sub.w /M.sub.n ≦(I.sub.10 /I.sub.2)-4.63; (iii) a density between than 0.850 and 0.91 g/cm 3 ; (iv) a critical shear rate at onset of surface melt fracture of at least 50 percent greater than the critical shear rate at the onset of surface melt fracture of a linear olefin polymer having about the same I 2 and M w /M n ; and (v) a melt index of between 1 and 200 g/10 min; B. Mixing into the melt of (A) at ambient temperature, between about 0.5 and about 5 parts per hundred resin of a silane crosslinker; C. Subjecting the melt of (B) to ionizing radiation or contacting the melt of (B) with a free radical initiator such that at least about 50 wt % of the silane cross linker graphs to the polymer of the melt of (A); D. Extruding the melt of (C) over a cable; and, optionally, E. Curing the melt extruded over the cable.

Claim 13

The process of claim 9 comprising an additional step of mixing into the melt of (A) prior to the addition of the silane crosslinker between 20 and 80 wt %, based on the weight of the polymer, of a filler.