CA2618726A1 - Hydrosilylation method - Google Patents

Abstract

The present invention relates to a hydrosilylation process comprising mixing an unsaturated base polymer, a silane compound and a platinum hydrosilylation catalyst consisting of a masterbatch composed of a polymer matrix in which solid platinum is dispersed. The invention is remarkable in that the solid platinum content of the mixture thus obtained is between 12 and 35 ppm, and preferably between 12 and 20 ppm.

Description

HYDROSILYLATION PROCESS

The present invention relates to a method for hydrosilylation which is intended in particular for preparation of a crosslinkable polymeric composition.
The invention finds an application particularly advantageous, but not exclusive, in the field of insulation and / or cladding materials energy and / or telecommunication cables, including including fiber optic cables.
Hydrosilylation is a grafting process that is widely used today, especially in the manufacture of silicones. It consists schematically grafting a silane compound onto an unsaturated polymer, with the aim of obtaining a composition polymer potentially crosslinkable.
Anyway, a hydrosilylation is carried out generally by mixing an unsaturated polymer with a silane compound, all in the presence of a catalyst of platinum-based hydrosilylation. In practice, the polymer is usually used in form solid, while the silane compound and the catalyst platinum are commonly used in form liquid.
This type of process however the disadvantage of being difficult to transpose to cable sector, since the substances used in the formulation are presented mostly in liquid form. Indeed, cable manufacturing equipment, including extruders, are generally adapted to be powered and then operate essentially with purely solid materials.

2 Such a hydrosilylation process also has the disadvantage of being extremely expensive, because mainly from the intrinsic cost of the catalyst liquid platinum. This is all the more true as the catalyst in question must necessarily be employed in large quantities to get results a so much not very homogeneous.
Also the technical problem to be solved by the object of the present invention is to provide a method hydrosilylation process comprising mixing a polymer of unsaturated base, a silane compound and a catalyst of platinum hydrosilylation constituted by a mixture master composed of a polymer matrix in which is dispersed platinum solid, hydrosilylation process which avoids the problems of the state of the in particular by offering an optimal match with the means of production of the cable, while being significantly less expensive.
The solution to the technical problem consists, according to the present invention, in that the content of solid platinum of the mixture thus obtained is included between 12 and 35 ppm, and preferably between 12 and 20 ppm.
It is understood that the basic unsaturated polymer can be of any known nature, and in particular an olefin. In a similar way, the silane compound very generally concerns any substance with silicon-hydrogen bonds Si-H.
The invention as thus defined presents the advantage of being perfectly compatible with existing cable manufacturing equipment, and especially extruders. Indeed, as long as the silane compound which is usually liquid

3 amalgamated with the conventionally unsaturated polymer solid, it is possible to carry out the mixing with the platinum catalyst, with materials that are totally solid at first. Being able to put implement the invention directly with the means of production of cable, is an advantage to the both technical and economical.
The use of a hydrosilylation catalyst in the form of masterbatch additionally allows a better dispersion of platinum within the mixture, hence a significantly higher efficiency. AT
equivalent effect, it is therefore possible to use substantially less catalyst, which implies a significant gain in terms of cost.
Another consequence of the decrease in the rate of platinum in the overall mixture, lies in the preservation of the electrical properties of the material final; these last ones being then hardly impaired by the presence of the conductive metal.
Finally, the conditioning of platinum in the form of master mix allows precise dosing really necessary catalyst, which proves to be fundamental in the context of the invention given that its final concentration must be of the order of only a few ppm or parts per million.
According to one particularity of the invention, the matrix polymer of the masterbatch is selected from the group polyolefins, copolymers of polyolefins, or any mixture of these components.
Particularly advantageously, nature of the polymer matrix of the masterbatch is identical to that of the unsaturated base polymer. This characteristic makes it possible not to modify the

4 mechanical, dielectric and resistance properties aging of the final material.
According to another feature of the invention, the solid platinum of the master mix consists of hexachloroplatinic acid.
In a particularly advantageous way, the content hydrosilylation catalyst is between 4 and 7% of the total amount of base polymer unsaturated.
According to another feature of the invention, the silane compound is a polyhydrosiloxane, and especially a polymethylsiloxane.
According to another characteristic of the invention, the content of silane compound is between 1 and 8% in relation to the quantity total unsaturated base polymer, and preferably between 4 and 6%.
According to another feature of the invention, the crosslinking process is implemented at a temperature which is between 100 and 125 C.
The invention also relates to any cable energy and / or telecommunication least one conductive element extending inside of at least one insulating element, and in which at least an insulating element is made of a crosslinked material following a hydrosilylation process such as previously described.
The invention is furthermore related to any cable energy and / or telecommunication with at least one conductive element extending within at least an insulating element, and further provided with at least one sheath made of a cross-linked material according to a hydrosilylation process as previously described.

Other features and benefits of the present invention will appear during the description which will follow and which is given as illustrative example and not limiting.

5 Preparation of the masterbatch The polymer matrix composing the masterbatch here is made of terpolymer of ethylene propylene norbornene.
The platinum-based hydrosilylation catalyst is in the form of an acid hexachloroplatinic compound of formula H2PtCl6, xH2O, and comprising 41.88% pure platinum element.
A first preparation A is elaborated in incorporating 1 g of hexachloroplatinic acid in 36 g of polymer, that is to say according to a proportion of 36 parts by weight of polymer per 1 part by weight of catalyst.
In concrete terms, this operation is carried out in a internal mixer to ensure good dispersion hydrosilylation catalyst within the matrix polymer. The applied temperature is slightly greater than the melting temperature of the terpolymer ethylene propylene norbornene, ie 110 C.
The preparation A thus obtained then contains 1.13% pure platinum. This content proving again too important for the intended application, it is proceeded to a new dilution operation.
A second preparation B is therefore developed at from lg of preparation A and 36g of terpolymer, in accordance with a proportion that of the first mixture, that is to say 36 parts in

6 polymer weight per 1 part by weight of preparation AT.
This second operation is logically following the same conditions as those previously described. An active platinum content of 0.03% is then obtained for this preparation B which thus forms advantageously a masterbatch conforming to the invention, that is to say, usable as hydrosilylation catalyst.
Preparation of the insulating material In an internal mixer maintained at 110 C, are first of all incorporated 100 parts by weight of a basic polymer that is in this example advantageously identical to that of the masterbatch, that is to say ethylene propylene terpolymer norbornene.
The quantities mentioned below are expressed in parts by weight per 100 parts of base (pcr).
Once the polymer is melted, it is then proceeded to the incorporation of the silane compound which is here in the form of a mixture of two constituents. It is as well as are added, on the one hand, 3 parts by weight of a polymethylhydrosiloxane with groups -SiH-along the chain, referenced later Siloxl, and on the other hand, 3 parts by weight of a polymethylhydrosiloxane provided with -SiH- groups in end of chain, referenced later Silox2.
The hydrosilylation catalyst is incorporated in turn, in the form of a master mix, in the occurrence of preparation B, so that the

7 solid platinum content of the mixture thus obtained either between 12 and 35 ppm, and preferably between 12 and 20 ppm.
Said mixture is in the following description defined as the final mix.
The mixing operation is carried out at a temperature of 125 C and for a period of 2 minutes.
Then, after this operation, the final mix self-reticle to ambient air.
To verify that cross-linking is achieved optimal using the process in accordance with the invention, hot creep measurements under mechanical stress were performed according to the standard NF EN 60811-2-1.
Hot creep is to ballast one end of a dumbbell type test tube with a mass corresponding to the application of a constraint equivalent to 0.2MPa, and to place the set in a oven heated to 200 +/- 1 C for a duration of 15 minutes.
In the case where a test piece breaks in trial course, under the combined action of the constraint mechanical and temperature, the test result is then considered a failure.
The tests of fluings are carried out on final blends whose compositions are detailed in table 1.

8 Final mix 1 2 3 4 Terpolymer of ethylene propylene norbornene 100 pcr Siloxl 3 pcr Silox2 3 pcr Magnesium Blend (Preparation B at 0.03%
3.5 pcr 4.5 pcr 7.0 pcr 13.3 pcr active platinum) Solid platinum content 10 ppm 13 ppm 20 ppm 36 ppm Table 1 The final mixtures 1 to 4 are used according to the method described above.
Table 2 shows the creep results at hot under mechanical stress concerning mixtures final 1 to 4.

Final mix 1 2 3 4 Number of days of self-crosslinking Out of Hot creep No break No break -specimen Table 2 The number of days of self-crosslinking is the minimum number of days required for do not break the specimen unless the crosslinking can not take place, as we can see with the test piece of the final mixture 1.
Indeed, after 20 days of self-crosslinking, the test piece of the final mixture 1 fails the test of creep due to its rupture during the 15 minutes of stay in the oven.
The amount of catalyst used, namely ppm, in the final mixture 1, is therefore not sufficient

9 to make it possible to obtain a final mixture with optimized creep properties.
Unlike the final mix test tube 1, the test pieces of the final mixture 2 and 3 exhibit very good hot creep properties under mechanical stress for very self-crosslinking fast, that is to say less than 7 days.
Finally, the final mixing test piece 4 could not undergo the creep test since the incorporation of catalytic masterbatch (preparation B at 0.03%
active platinum) in the hot polymer blend of unsaturated base with silane compounds gives rise to reaction kinetics too fast to be control.
As a result, the number of links created becomes too important for the final mix to remain convertible.
The continuation of the mixing is then impossible since it degrades the final mixture by breaking the chains.
So for a solid platinum content greater than or equal to 36 ppm, the final mixture is unusable and so it can not be formatted.
The present invention is not limited to examples of implementation which have just been described and carries in its generality on all the processes possible from the general indications provided in the disclosure of the invention.

Claims (10)

1. A method of hydrosilylation comprising mixing an unsaturated base polymer, a silane compound, and a platinum hydrosilylation catalyst consisting of a master mix consisting of a polymer matrix in which is dispersed solid platinum, characterized in that the solid platinum content of the mixture thus obtained is between 12 and 35 ppm, and preferably between 12 and 20 ppm. 2. The crosslinking process according to claim 1, characterized in that the polymer matrix of the mixture master is selected from polyolefins and their copolymers, or any mixture of these components. 3. Crosslinking process according to one of 1 or 2, characterized in that the matrix masterbatch polymer and base polymer unsaturated are of identical nature. 4. Crosslinking process according to any one of Claims 1 to 3, characterized in that the platinum solid of the masterbatch consists of acid hexachloroplatinic. 5. Crosslinking process according to any one of Claims 1 to 4, characterized in that the content hydrosilylation catalyst is between 4 and 7% of the total amount of base polymer unsaturated. 6. Crosslinking process according to any one of Claims 1 to 5, characterized in that the compound silane is a polyhydrosiloxane. 7. Crosslinking process according to any one of Claims 1 to 6, characterized in that the content silane compound is between 1 and 8% per in relation to the total amount of base polymer unsaturated, and preferably between 4 and 6%. 8. Crosslinking process according to any one of Claims 1 to 7, characterized in that it is at a temperature of between 100 and 125 ° C. 9. Cable having at least one conductive element extending inside at least one insulating element, characterized in that at least one insulating element is made of a cross-linked material according to a method hydrosilylation according to any one of preceding claims. 10. Cable having at least one conductive element extending inside at least one insulating element, characterized in that it further comprises at least one sheath made of a cross-linked material according to a hydrosilylation process according to any one Claims 1 to 8.