SILANE CROSSLINKABLE FOAMABLE POLYOLEFIN COMPOSITION AND FOAM

1 . A polyolefin composition comprising:

(A) a polyethylene bearing hydrolysable silane groups,

(B) a silanol condensation catalyst,

(C) a blowing agent, and

(D) a cell nucleating agent,

wherein the polyethylene bearing hydrolysable silane groups (A) is a copolymer of ethylene and a comonomer comprising a hydrolysable silane group and further comprises comonomer units comprising a polar group, wherein the comonomer units comprising a polar group are obtained from a comonomer selected from the group consisting of acrylic acid, methacrylic acid, acrylates, methacrylates, vinyl esters, and mixtures thereof, and

wherein the blowing agent (C) comprises a physical blowing agent or a mixture of physical blowing agents.

2 . The polyolefin composition according to claim 1 , wherein the comonomer comprising a hydrolysable silane group is represented by the following formula:

R 1 SiR 2 q Y 3-q

wherein R 1 is an ethylenically unsaturated hydrocarbyl, hydrocarbyloxy or (meth)acryloxy hydrocarbyl group,

each R 2 is independently an aliphatic saturated hydrocarbyl group,

Y, which may be the same or different, is a hydrolysable organic group, and

q is 0, 1 or 2.

3 . The polyolefin composition according to claim 1 , wherein the comonomer comprising a hydrolysable silane group is represented by the following formula:

CH 2 ═CHSi(OA) 3

wherein A is a hydrocarbyl group having 1 to 8 carbon atoms.

4 . The polyolefin composition according to claim 1 , wherein the silanol condensation catalyst (B) comprises an organic sulphonic acid or a precursor thereof including an acid anhydride thereof, or an organic sulphonic acid that has been provided with at least one hydrolysable protective group.

5 . The polyolefin composition according to claim 1 , wherein the content of the comonomer units comprising a polar group is 2.0 to 35.0 wt % based on the weight of the polyethylene bearing hydrolysable silane groups (A).

6 . The polyolefin composition according to claim 1 , wherein the content of the hydrolysable silane groups is 0.2 to 4.0 wt % based on the weight of the polyethylene bearing hydrolysable silane groups (A).

7 . The polyolefin composition according to claim 1 , wherein the amount of the polyethylene bearing hydrolysable silane groups (A) is 20.0 to 98.0 wt % based on the weight of the polyolefin composition.

8 . The polyolefin composition according to claim 1 , wherein the amount of the silanol condensation catalyst (B) is 1.0 to 9.0 wt % based on the weight of the polyethylene bearing hydrolysable silane groups (A).

9 . The polyolefin composition according to claim 1 , wherein the amount of the blowing agent (C) is 0.1 to 10 wt % based on the weight of the polyolefin composition.

10 . The polyolefin composition according to claim 1 , wherein the amount of the cell nucleating agent (D) is 0.1 to 5.0 wt % based on the weight of the polyolefin composition.

11 . The polyolefin composition according to claim 1 , wherein the cell nucleating agent (D) is a physical nucleating agent.

12 . A crosslinked foam obtained from a polyolefin composition according to claim 1 .

13 . A process for producing a crosslinked foam comprising the following steps:

a) providing a polyolefin composition, wherein the polyolefin composition is as defined in claim 1 ,

b) extruding the polyolefin composition through a die of an extruder,

c) allowing the extruded polyolefin composition to expand at ambient conditions, and

d) allowing the extruded polyolefin composition to crosslink at ambient conditions.