Patent GB-644282-A (GB)
Title: Improvements in or relating to a method of making oil-and heat-resisting gasket material
IPC: C08K7/04
Filed: 1945-03-23
Abstract: Oil- and heat-resistant gasket material comprises fibrous material admixed or impregnated with a compressible resilient silicone derived from chlorosilanes or a chlorosilane, said mixture or said silane containing two different monovalent aliphatic hydrocarbon groups, the ratio of the number of hydrocarbon groups to the number of silicon atoms being such as to produce a rubbery resilient binder for the fibrous material. Preferably the hydrocarbon radicals are alkyl groups differing from each other by at least 3 carbon atoms, and normally the ratio of hydrocarbon groups to silicon atoms is between 2 : 1 and 0.5 : 1.  The starting materials may be silicon tetrachloride or oxyhalide, disilicon hexahalide or polysilicon polyhalide. Suitable fibrous material is asbestos, fibre glass, canvas, cork or linen, and it may have wire reinforcement.  Silicon derivatives having a high proportion of methyl groups are best in heat resistance and may also contain, for example, butyl- or cetyl-silicon groups.  In an example mixtures are made of hydrolysis products of methyl silicon chloride and butyl silicon chloride containing 1.62 methyl radicals and 1.1 butyl radicals per silicon atom respectively, with asbestos.  The mixture is moulded at 175 DEG C. and 5000 lbs. per square inch to form a moulding from which gaskets may be cut.  The Specification as open to inspection under Sect. 91 comprises also gasket material having as binder products obtained by hydrolysing and dehydrating compounds of the formula RxSi(OR1)4-x, where R may be an alkyl, alkynyl, alkenyl, olefinyl, aryl, aralkyl, alkaryl or cycloalkyl radical which may be halogen-substituted, R1 is hydrogen, or a group such as R, or a group R11-CO-, where R11 is hydrogen or a group such as R.  Examples of such radicals are methyl. vinyl, allyl, butenyl, propargyl, ethyl, propyl, isopropyl, butyl, isobutyl, amyl, hexyl, heptyl, octyl, phenyl, tolyl, xenyl, benzyl, cyclohexyl, chloropropyl, chlorophenyl for R, and acid groups are those of acetic, stearic, maleic, chloropropionic, phthalic, and benzoic acids.  Organo-halosilanes from silicon tetraiodide are also mentioned.  Hydrolysis products or their polymers which have been acylated, e.g. of the formula R1SiO.CO.R or <FORM:0644282/IV (a)/1> may also be used, R and R1 being alkyl, unsaturated aliphatic, aryl or aralkyl.  The acylation, e.g. with acid anhydrides or chlorides, is preferably carried out in the presence of pyridine or other tertiary bases of which several are mentioned.  Examples describe the preparation of silicon derivatives suitable after curing as binders, in which: (1) an ethyl silicon chloride (1.6 ethyl radicals per Si) is hydrolysed p  and cured; (2) ethyl silicon chloride is hydrolysed and acetylated by heating with acetic anhydride; (3) butyl silicon chloride is hydrolysed to yield (n-C4H9)1.2Si(OH)2.8, whic is then reacted with stearoyl chloride; (4) an ethyl butyl siliconate n-C4H9Si(OC2H5)3 is reacted at 150 DEG C. with phthalic anhdyride and the product dissolved in dioxan for impregnation; (6) ethyl orthosilicate and water in 1 : 1 molar ratio together with ethanol are refluxed, mixed with n-butyl silicon tri-hydroxide and heated again to yield a rubbery gel. Also included is the subject-matter of Specifications 635,194 and 643,964 and some matter which is described in the Abridgment of Specification 643,964 as open to inspection under Sect. 91.  This subject-matter does not appear in the Specification as accepted.ALSO:Hydrocarbon silicon halides are prepared by reacting a Grignard reagent or mixtures thereof with a silicon halide or orthosilicic acid ester or by reacting magnesium or lithium, a hydrocarbon halide and the silicon halide.  Large numbers of hydrocarbon groups, which may contain substituents, are specified.  Suitable silicon halides mentioned are silicon tetrahalides, silicon oxyhalides, disilicon hexahalides, or polysilicon polyhalides. The products may be hydrolysed to the corresponding silicols and then acylated with acylating agents, e.g. acetic anhydride, stearoyl chloride, maleic anhydride, chloropropionyl chloride, phthalic anhydride or benzoyl chloride.