Low speed cross-linking catalyst for silane-grafted plastomers

Abstract

The present invention relates to silane crosslinking catalyst comprising: —75 to 85 wt.-% of an olefin acrylate interpolymer and—15 to 25 wt.-% of a hindered amine light stabilizer (HALS) having a number average molecular weight Mn of 1500 to 4000 g/mol; and—optionally up to 5 wt.-% wax, wherein the silane crosslinking catalyst is free of tin, carboxylic acid(s) and sulphonic acid(s), all weight percentages with respect to the total weight of the silane crosslinking catalyst.

Claims

1. A silane crosslinking catalyst comprising  75 to 85 wt.-% of an olefin acrylate interpolymer and  15 to 25 wt.-% of a hindered amine light stabilizer (HALS) having a number average molecular weight Mn of 1500 to 4000 g/mol; and  optionally up to 5 wt.-% wax,  wherein said olefin acrylate interpolymer is ethylene butyl acrylate copolymer (EBA) having a content of butyloxy group O—CH.sub.2—CH.sub.2—CH.sub.2—CH.sub.3 of 15 to 20 wt.-% with respect to the ethylene butyl acrylate copolymer (EBA), and/or a melt flow rate of 5.0 to 10.0 g/10 min (ISO1133, 2.16 kg load, 190° C.); wherein the silane crosslinking catalyst is free of tin, carboxylic acid(s), and sulphonic acid(s), and wherein all weight percentages are with respect to the total weight of the silane crosslinking catalyst.

2. The silane crosslinking catalyst according to claim 1, wherein the hindered amine light stabilizer (HALS) has a melting temperature of at least 95° C.; and/or the wax is present in an amount of 2.0 wt.-% or less with respect to the total weight of the silane crosslinking catalyst.

3. The silane crosslinking catalyst according to claim 1, wherein the silane crosslinking catalyst does not contain a butylated reaction product of p-cresol and dicyclopentadiene.

4. The silane crosslinking catalyst according to claim 1, wherein the silane crosslinking catalyst does not contain an alkoxysilane.

Description

EXAMPLE 1

(1) The silane crosslinking catalysts RC1, RC2 and IC2 were tested on plastomers subjected to grafting. The used reactants are indicated in Table 1.

(2) TABLE-US-00001 TABLE 1 Crosslinking degree of the inventive silane crosslinking catalyst IC1 (24 h, 48 h, 4 days) Plastomer Gel content after MFR Density VTMS crosslinking at RT Name (g/10 min) (kg/m.sup.3) % IC1 24 h 48 h 4 days P1 0.5 863 2.0 5% 8%  8% 22% P2 1 857 1.8 5% 5% 13%  7% P3 0.5 861 1.7 5% 11%  20% 32%

(3) It can be seen the crosslinking degree remained on a surprisingly low level even for up to 4 days.

(4) TABLE-US-00002 TABLE 2 Crosslinking degree of the reference silane crosslinking catalyst RC2 (24 h, 48 h, 4 days) Plastomer Gel content after MFR Density VTMS crosslinking at RT Name (g/10 min) (kg/m.sup.3) % RC2 24 h 48 h 4 days P1 0.5 863 2.0 5% 96% 96% 96% P2 1 857 1.8 5% 96% 96% 96% P3 0.5 861 1.7 5% 96% 96% 96%

(5) TABLE-US-00003 TABLE 3 Crosslinking degree of the reference silane crosslinking catalyst RC1 (24 h, 48 h, 4 days) Plastomer Gel content after MFR Density VTMS crosslinking at RT Name (g/10 min) (kg/m.sup.3) % RC1 24 h 48 h 4 days P1 0.5 863 2.0 5% 96% 96% 96% P2 1 857 1.8 5% 96% 96% 96% P3 0.5 861 1.7 5% 96% 96% 96%

(6) It can be seen the crosslinking degree could not be maintained at a low level e.g. for storage.

(7) All tests were made on 2 mm extruded tapes using 95% plastomer (Engage and Queo) and 5% of a catalyst.

EXAMPLE 2

(8) All tapes using IC1 (Table 1) after experimental treatment for 4 days were (as described above) were placed in a water bath using deionized water at 90° C. for 24 hours.

(9) TABLE-US-00004 TABLE 4 Crosslinking degree of the inventive silane crosslinking catalyst IC1 after cross-linking in water bath. Plastomer Gel content after MFR (g/10 Density VTMS crosslinking at Name min) (kg/m.sup.3) % IC1 90° C. for 24 h P1 0.5 863 2.0 5% >70% P2 1 857 1.8 5% >70% P3 0.5 861 1.7 5% >70%

(10) IE1 showed crosslinking of above 70% gel content, i.e. Cooper Standard specification (minimum 70% gel content) after 24 h was met.

(11) The inventive silane crosslinking catalysts allows modifying reaction rates according to the industrial needs.

EXAMPLE 3

(12) The production operation included an extrusion of a rubber like tube which is reinforced in another step by a fabric material.

(13) Cooling and forming was effected under water thereby forming a hose. The hoses were cut to the required length providing semi-finished products. The semi-finished products were maintained at 23° C. and 55% relative humidity for 4 days.

(14) After that the semi-finished products were placed on the shaped mandrels and subjected to curing (autoclave, 20 minute curing program consisting of 10 minutes at 140° C. at 3.6 bar and 10 min at 7.6 bar).

(15) Then cured hoses were removed from the mandrels. Shape retention was observed.

(16) Gel content was measured and was well above 70%.

(17) It could be shown the silane crosslinking catalysts allows an extremely advantageous process for providing a fluids transport products.