Silicon containing compound as processing aid for polyolefin compositions

1. A process for reducing the retention time of a polyolefin composition comprising a crosslinkable polyolefin with hydrolysable silane groups in an extruder and/or reducing the extrusion temperature during the extrusion of the polyolefin composition, the process comprising:

adding a master batch to the polyolefin composition to form a compounding composition; and

compounding the compounding composition in the extruder;

wherein the master batch comprises:

a matrix polymer;

a silanol condensation catalyst, wherein the silanol condensation catalyst is a Brönsted acid and is present in an amount of 0.7 to 3.5 wt % of the master batch; and

a silicon containing compound in an amount of from 2 to 10 wt % of the master batch, having the structure of formula (I):

(R 1 ) x [Si(R 2 ) y (R 3 ) z ] m   (I)

wherein

R 1 is a linear or branched C 6 - to C 22 -alkyl group;

R 2 is a linear or branched C 1 - to C 10 -alkoxy group;

R 3 is —R 4 SiR 1 p R 2 q , wherein p is 0 to 3, q is 0 to 3, with the proviso that p+q is 3; and

R 4 is —(CH 2 ),Y s (CH 2 ) t —where r and t independently are 1 to 3, s is 0 or 1 and Y is a difunctional heteroatomic group selected from —O—, —S—, —SO—, —SO 2 —, —NH—, —NR 1 — or —PR 1 —, where R 1 and R 2 are as previously defined; and

x is 0 to 3, y is 1 to 4, z is 0 or 1, with the proviso that x+y+z=4;

and m =1; and

wherein the amount of the silicon containing compound is 0.01 to 1.5 wt % of the compounding composition.

2. The process of claim 1 , wherein in the formula for the silicon containing compound:

x=1, y=3, and, z=0.

3. The process of claim 1 , wherein the silicon containing compound comprises hexadecyl trimethoxy silane.

4. The process of claim 1 , wherein the crosslinkable polyolefin with hydrolysable silane groups comprises a polyethylene with hydrolysable silane groups.

5. The process of claim 4 , wherein in the crosslinkable polyolefin with hydrolysable silane groups the silane groups are present in an amount of 0.001 to 15 wt %.

6. The process of claim 1 , wherein the silanol condensation catalyst comprises an organic sulphonic acid.

7. The process of claim 6 , wherein the organic sulphonic acid comprising 10 C-atoms or more, the sulphonic acid further comprising at least one aromatic group.

8. The process of claim 6 , wherein the organic sulphonic acid comprises the structural element:

Ar(SO 3 H) x   (II)

with Ar being an aryl group which may be substituted or non-substituted, and x being at least 1.

9. The process of claim 8 , wherein in formula (II) Ar is substituted with at least one C 4 - to C 30 -hydrocarbyl group and the silanol condensation catalyst comprises from 10 to 200 C-atoms.

10. The process of claim 1 , wherein the polyolefin composition has an MFR 21 (190° C., 21.6 kg) of 50 g/10 min or more when extruded at any temperature in the range of from 20 to 240° C.

11. The process of claim 1 , wherein the amount of the silicon containing compound is 0.2 wt % to 0.5 wt % of the compounding composition;

wherein the silicon containing compound is hexadecyl trimethoxy silane; and wherein the silanol condensation catalyst is dodecylbenzene sulfonic acid.