Stock material or miscellaneous articles – Composite – Of silicon containing
Reexamination Certificate
2001-09-26
2003-01-28
Moore, Margaret G. (Department: 1712)
Stock material or miscellaneous articles
Composite
Of silicon containing
C528S015000, C528S031000, C442S164000, C524S588000, C523S212000
Reexamination Certificate
active
06511754
ABSTRACT:
CROSS-REFERENCE
This application is the National Stage of International Application No. PCT/FR99/03213, filed Dec. 21, 1999, which was published by the International Bureau in French on Jun. 6, 2000. This application claims priority to French Application No. 98/16510, field Dec. 23, 1998.
The general field of the invention is that of cold-curing silicone compositions (but the curing of which is in general accelerated e.g. by heat), in particular those of the two-component type (RTV II), which crosslink by hydrosilylation or polyaddition in order to produce a thin-film elastomer. These crosslinked compositions are, among others, suitable as a coating, for example for protection or for mechanical reinforcement, on various substrates made of, in particular, textile material, such as woven, knitted or non-woven fibrous substrates, for example.
Such silicone coatings are generally obtained by coating the substrate, followed by curing, which proceeds by the polyaddition of unsaturated (alkenyl, e.g. Si-Vi) groups of one polyorganosiloxane onto hydrogen groups of another polyorganosiloxane.
These silicone compositions have found a major outlet in the coating of flexible—woven, knitted or non-woven—materials used for the manufacture of bags for the individual protection of the occupants of vehicles, also called “airbags”.
For more details about airbags, reference may be made, in particular, to French Patent FR-A-2,668,106.
The present invention relates in particular, but not exclusively, to the application of the compositions according to the invention in the manufacture of such airbags.
Conventionally, the latter are formed from a fabric made of synthetic fibre, for example made of polyamide (nylon), covered on at least one of its sides with a layer of an elastomer of the chloroprene type. The presence of such a protective layer or coating is necessary because of the fact that the gases released by the gas generator (for example: carbon monoxide, NO
x
) in the event of an impact are extremely hot and contain incandescent particles capable of damaging the nylon bag. The inner protective layer of elastomer must therefore be particularly resistant to high temperatures and to mechanical stresses. It is also important that this elastomer coating be in the form of a uniform thin film adhering strongly to the substrate made of synthetic fabric which forms the walls of the airbag.
In order to prevent the gases released by the gas generator from getting into the passenger compartment, it is important to ensure that the airbag exhibits good and constant impermeability. The elastomer coating must also allow this objective to be achieved, even when deposited in small amounts.
Another constraint which is imposed on the elastomer coating is that of the ageing behaviour, i.e. the retention of the thermal, mechanical and adhesion properties over time. This constraint is all the more acute since the airbags are stored in folded form in motor vehicles, before their possible life-saving expansion in the event of an accident.
As another criterion, one which is not negligible, it should be noted that the protective coating must not cause problems with regard to the manufacture, by stitching, of the airbag.
Silicone compositions have readily supplanted chloroprenes in this application since it has turned out that the latter do not satisfactorily meet all the specifications referred to above. There has been a diversification of silicone coating compositions and bags containing them in order to promote certain properties.
According to EP-A-0,553,840, known silicone compositions comprise:
a polydiorganosiloxane having at least two alkenyl groups per molecule,
a polyorganohydrogenosiloxane having at least two hydrogen atoms linked to the silicon in each molecule,
a metal catalyst, the metal being of the platinum group,
an adhesion promoter consisting of an epoxy-functional organosilicon compound,
an inorganic filler, e.g. reinforcing fillers such as fumed titanium oxide, microparticulate silica, e.g. fumed silica, precipitated silica, pyrogenic silica, non-reinforcing fillers, such as quartz powder, diatomaceous earths, iron oxides, aluminium oxides, calcium carbonate or magnesium carbonate; e.g. a silica treated by an organosilane, an organosilazane or a diorganocyclopolysiloxane is incorporated,
a polyorganosiloxane resin,
and optionally a compound used as a crosslinking inhibitor.
In U.S. Pat. No. 5,296,298, the first six aforementioned constituents are again found but it should be noted that the adhesion promoter consists here of the combination of an epoxy-functional organosilicon compound with an alkoxylated silane containing, per molecule, a (meth)acryl or (meth)acryloxy group and, optionally, with an aluminium chelate, while the inorganic filler is given as being optional, although it (quartz or silica) is used in all the examples, 1 to 20, illustrating the invention. As examples of fillers, this document mentions fumed silica, precipitated silica, powdered quartz, diatomaceous earths and glass beads.
However, the aforementioned known silicone compositions suffer from the drawback of not adhering sufficiently well to the polyamide fabric of the bag in order to guarantee optimum reliability.
In EP-A-0,681,014 it was sought to obtain a silicone composition which can be applied in particular as an airbag inner coating and which, for this purpose, has more favourable properties in terms of, in particular, fire and temperature resistance, mechanical properties, ageing behaviour, adhesion and surface uniformity, the adhesion to substrates made of textile material being most particularly desirable. The solution proposed consisted in using:
a silicone coating composition of the type of those which are cold-curing (RTV) consisting of the mixture formed by:
(I) at least one polyorganosiloxane having, per molecule, at least two C
2
-C
6
alkenyl groups linked to the silicon,
(II) at least one polyorganosiloxane having, per molecule, at least two hydrogen atoms linked to the silicon,
(III) a catalytically effective amount of at least one catalyst, composed of at least one metal belonging to the platinum group,
(IV) an adhesion promoter,
(V) optionally a filler, preferably a mineral filler,
(VI) optionally at least one crosslinking inhibitor
(VII) and optionally at least one polyorganosiloxane resin,
in which the adhesion promoter consists exclusively of the at least ternary combination of the following ingredients:
(IV.1) at least one alkoxylated organosilane containing, per molecule, at least one C
2
-C
6
alkenyl group,
(IV.2) at least one organosilicon compound which includes at least one epoxy radical,
(IV.3) at least one metal M chelate and/or one metal alkoxide of general formula: M(OJ)
n
, with n=the valency of M and J=a linear or branched C
1
-C
8
alkyl, M being selected from the group formed by: Ti, Zr, Ge, Li, Mn, Fe, Al and Mg.
In EP-A-0,681,014, the mineral filler may fulfil the function of a reinforcing or semi-reinforcing filler. These reinforcing fillers may be chosen from colloidal silicas and pyrogenic and precipitated silica powders. These powders have a mean particle size of generally less than 0.1 &mgr;m and a BET specific surface area greater than 50 m
2
/g, preferably between 150 and 350 m
2
/g. The semi-reinforcing fillers may be diatomaceous earths or ground quartz, or else non-siliceous mineral substances generally having a particle size of between 0.001 and 300 &mgr;m and a BET specific surface area of less than 100 m
2
/g. Preferably, the filler is a mixture of quartz and silica.
These various inventors were preoccupied above all with improving the adhesion of silicone elastomers to substrates and with the fineness of the elastomeric layer.
The Applicant was given the objective of substantially improving the mechanical properties of these elastomers, most particularly the elongation at break or extensibility, without thereby compromising the other properties.
It is an object of the present invention especially to provide coating compositions resulting in elastomers whose
Bohin Fabrice
Pouchelon Alain
Prebet Christiane
Burns Doane Swecker & Mathis L.L.P.
Moore Margaret G.
Rhodia Chimie
LandOfFree
Silicone composition for coating textile material substrates does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Silicone composition for coating textile material substrates, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Silicone composition for coating textile material substrates will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3011134