Process For The Continuous Manufacturing Of Shaped Articles And Use Of Silicone Rubber Compositions In That Process

Abstract

The present invention relates to a process for the manufacturing of continuously shaped cured silicone articles, particularly extrusions articles and the use of silicone compositions containing a photoactivatable metal catalyst in said process, wherein the curing is initiated by visible or UV-light.

1 . A process for the manufacture of shaped cured silicone articles comprising the following steps:
 a) a shaping step, comprising the continuous shaping of a mixture comprising:
 (i) at least one linear polyorganosiloxane having at least three alkenyl groups and an average number of diorganosiloxy units determined by GPC with polystyrene as standard of at least 3000, 
 (ii) optionally one or more polyorganosiloxane having alkenyl groups, other than the polyorganosiloxane according to the component (i), 
 (iii) at least one polyorganosiloxane having at least two SiH groups, 
 (iv) at least one photoactivatable transition metal catalyst, 
 (v) optionally one or more filler, 
 (vi) optionally one or more conventional additives, 
 in a shaping apparatus, thereby obtaining a shaped silicone article, 
   b) at least one irradiation step to photoactivate the photoactivatable transition metal catalyst,   c) optionally one or more heat treatment steps,   d) optionally one or more mixing steps,   e) optionally one or more cutting and/or winding and/or packaging steps of the continuously shaped cured silicone article.   
     
     
         2 . A process according to  claim 1  wherein the polyorganosiloxane (i) has at least one pendant alkenyl group. 
     
     
         3 . A process according to  claim 1  wherein the part of the uncured mixture of the components (i) to (vi), which is soluble in CDCl 3  at 25° C., has a content of vicinal Si-alkenyl groups of less than 0.025 mol. %. 
     
     
         4 . A process according to  claim 1  wherein the polyorgano-siloxanes (i) has a viscosity of at least 1.5 kpa*s (25° C.; at a shear rate of 1 s −1 ). 
     
     
         5 . A process according to  claim 1  wherein the mixture to be shaped comprising the components (i). (iii), (iv) and optionally (ii), (v) and (vi), has a viscosity of at least of 10 Mooney units. 
     
     
         6 . A process according to  claim 1  wherein the photoactivatable transition metal catalyst is selected from the group of transition metal complex compounds having sigma-bonded ligands. 
     
     
         7 . A process according to  claim 1  wherein the photoactivatable transition metal catalyst is selected from the group of transition metal complex compounds having at least one ligand selected from the group consisting of cyclopentadienyl, cyclooctadiene, cyclooctatetraene, norbornadiene. 
     
     
         8 . A process according to  claim 1  wherein the filler is selected from the group reinforcing fillers. 
     
     
         9 . A process according to  claim 1  wherein the shaping apparatus comprises at least one shape forming die. 
     
     
         10 . A process according to  claim 1  wherein the continuous shaping step is an extrusion step and the shaping apparatus is an extruder. 
     
     
         11 . A process according to  claim 10  wherein the extruder is selected from single-screw extruders, twin screw extruders and gear extruders. 
     
     
         12 . A process according to  claim 1  wherein the irradiation step b) is carried out with light of a wavelength in the range from 190 to 600 nm. 
     
     
         13 . A process according to  claim 1  wherein the heat treatment step (c) is performed at an oven temperature from 50° C. to 250° C. 
     
     
         14 . A process according to  claim 1  wherein the heat treatment step (c) is performed at a surface temperature of the shaped article of 20 to 200° C. 
     
     
         15 . A shaped light-cured silicone extrudate obtained by the process of  claim 1 . 
     
     
         16 . A shaped light-cured silicone extrudate according to  claim 15 , having the form of a sheet, a tube, a cable, a cable jacket, a wire insulation, a profile, or a sheathing. 
     
     
         17 . A shaped co-extrudate comprising the light-cured silicone extrudates, obtained by the process of  claim 1  in association with at least one further extruded material. 
     
     
         18 . A shaped light-cured co-extrudate according to  claim 17  having the form of a sheet, a tube, a cable, a cable jacket, a profile, a sheathing. 
     
     
         19 . A continuously formed shaped silicone article comprising at least one polyorganosiloxane having at least three alkenyl groups, an average number of diorganosiloxy units determined by GPC with polystyrene as standard of at least 3000, and a the content of vicinal alkenyl groups of less than 0.025 mol. %. 
     
     
         20 . A composition comprising:
 (i) at least one polyorganosiloxane having at least three alkenyl groups and an average number of diorganosiloxy units determined by GPC with polystyrene as standard of at least 3000,   (ii) optionally one or more polyorganosiloxane having alkenyl groups, other than the polyorganosiloxane according to the component (i),   (iii) at least one polyorganosiloxane having at least two SiH groups,   (iv) at least one photoactivatable transition metal catalyst,   (v) optionally one or more filler, and   (vi) optionally one or more conventional additives.   
     
     
         21 . A composition according  claim 20  comprising the components (i) to (vi) in the amounts of:
 (i) 100 parts by weight,   (ii) 0 to 100 parts by weight,   (iii) 0.1 to 30 parts by weight,   (iv) 1 to 100 ppm (referring to the amount of the transition metal in the photoactivatable transition metal catalyst in relation to the total amount of components (i) to (iii)),   (v) 0 to 100 parts by weight,   (vi) 0 to 15 parts by weight.   
     
     
         22 . A cured composition, obtained by light-curing the compositions according to  claim 20 . 
     
     
         23 . A continuously formed cured shaped article comprising the composition of  claim 20 . 
     
     
         24 . An extrusion line, comprising:
 a) at least one extrusion means,   b) at least one irradiation means,   c) optionally at least one heating means,   d) optionally at least one conveying means, and   e) at least one packaging means.   
     
     
         25 . A continuous extrusion process for the manufacture of cured silicone extrudates, comprising:
 mixing the following components:
 (i) at least one linear polyorganosiloxane having at least three alkenyl groups and an average number of diorganosiloxy units determined by GPC with polystyrene as standard of at least 3000, 
 (ii) optionally one or more polyorganosiloxane having alkenyl groups, other than the polyorganosiloxane according to the component (i), 
 (iii) at least one polyorganosiloxane having at least two SiH groups, 
 (iv) at least one photoactivatable transition metal catalyst, 
 (v) optionally one or more filler, 
 (vi) optionally one or more conventional additives, 
   feeding said mixture obtained into an extruder,   extruding said mixture through a die to obtain a continuously formed extrudate,   conveying said extrudate obtained to an irradiation stage,   irradiating said extrudate with light of a wavelength in the range from 190 to 600 nm to obtain a continuously formed, cured silicone extrudate,   collecting said continuously formed, cured silicone extrudate, and   optionally cutting said continuously formed, cured silicone extrudate.