| 摘要 |
The present invention concerns a crosslinkable silicone elastomer composition and a method using the composition according to the invention for forming sealing gaskets and assembly seals for the components of a powertrain. The silicone elastomers prepared from the composition according to the invention have: good mechanical strength properties such as shore hardness, breaking strength, modulus at 100% elongation and good resistance to ageing in chemically aggressive fluids such as those used, for example, in a powertrain, in this case engine oils, lubricants for the gearbox and axle, oil/petrol mixtures, coolant liquids, fuels or antifreeze liquids, and good adhesion properties even on surfaces polluted by oils used in a powertrain. |
| 主权项 |
1. A polyorganosiloxane composition X that is crosslinkable into elastomer in the presence of moisture provided by ambient air or by prior addition of water, via polycondensation reaction comprising:
A) at least one polyorganosiloxane A comprising at least one alkoxylated group and comprising identical or different siloxyl units, of formula:
(Z)b(R4)aSiO[4−(a+b)]/2 (1) in which:
the symbol Z=[—(OCH2CH2)c—OR5], with c=0 or 1,
a=0, 1, 2 or 3; b=0, 1, 2 or 3, a+b=0, 1, 2 or 3,the symbol R4 represents a C1 to C13 monovalent hydrocarbon-based radical,the symbol R5 represents a C1 to C6 monovalent hydrocarbon-based radical or an alkoxyalkyl radical optionally comprising an ester function, andwith the condition that for at least one siloxyl unit, the index b≧1 such that the polyorganosiloxane A contains at least one alkoxylated group Z,B) optionally at least one polyalkoxylated silane B of formula:
(R2)zSi(OR3)(4−z) (2) in which:
z=0 or 1,
the symbol R2 represents a C1 to C13 monovalent hydrocarbon-based radical, and
the symbols R3, which may be identical or different, each represent a C1 to C6 monovalent hydrocarbon-based radical or an alkoxyalkyl radical optionally containing an ester function,C) at least one acetylene black D whose function is to absorb an oil used in a powertrain,D) at least one aluminum trihydrate E as mineral filler,E) at least one adhesion promoter F bearing at least one amine function,F) a catalytically effective amount of at least one guanidine G as condensation catalyst,G) optionally at least one unreactive linear polyorganosiloxane H,H) optionally at least one filler I, different from E, andI) optionally at least one additive J such as a coloring base, a pigment or a thixotropic agent,with the additional conditions that
said polyorganosiloxane composition X contains neither any calcium carbonate nor any siloxane containing from 2 to 10 siloxyl units obtained by partial hydrolysis and condensation of a polyalkoxylated silane, and thatthe polyorganosiloxane A has a number of units strictly greater than 10, optionally greater than 20 and at most equal to 2000. |
