Patent GB-638317-A (GB)
Title: Improvements in and relating to liquid polysiloxane oils
Filed: 1947-09-23
Abstract: A lubricating oil having a low boundary friction coefficient consists of a liquid aliphatic-substituted polysiloxane, containing in the molecule an average of from 1.9 to 2.5 aliphatic groups per silicon atom, and from 0.1 to 1 per cent of a saturated fatty acid containing 8 to 14 carbon atoms in the molecule. Suitable fatty acids are lauric, myristic, capric, caprylic, pelargonic, undecanoic, tridecanoic and 2-ethyl hexanoic acids. Suitable liquid aliphatic-substituted polysiloxanes may be prepared by the hydrolysis of aliphatic-substituted silanes, e.g. dialiphatic-substituted dihalogenosilanes, for instance, dimethyl dichlorosilane, followed by complete or partial condensation of the hydrolysis product.  They may also be prepared by hydrolysing mixtures of hydrolysable dialiphatic-substituted silanes, either among themselves or with other hydrolysable silanes containing, for example, three aliphatic radicals substituted on the silicon atom, for instance, trimethyl chlorosilane.  The hydrolysable aliphatic-substituted silanes are those derivatives of SiH4 which contain hydrolysable groups or radicals, e.g. halogens, amino groups, alkoxy, aryloxy and acyloxy radicals, in addition to the aliphatic groups.  Examples of such aliphatic groups are alkyl radicals, e.g. methyl, ethyl, propyl, isopropyl and butyl, and alkenyl radicals such as vinyl, allyl and methallyl.  If desired, the aliphatic groups may also contain substituents, for instance, halogens.  In examples, n-capric, lauric or myristic acid is added to a liquid methyl polysiloxane. Specifications 586,187, 586,188, 586,189, [all in Group IV], and 630,911, [Group IV (c)], are referred to.  The Specification as open to inspection under Sect. 91 refers to the use of proportions of saturated fatty acid in excess of 1 per cent, proportions up to 5 per cent being mentioned.  Liquid cycloaliphatic-substituted polysiloxanes derived from substituted silanes containing such alicyclic radicals as cyclopentyl or cyclohexyl may also be employed. This subject-matter does not appear in the Specification as accepted.ALSO:A lubricating oil having a low boundary friction coefficient consists of a liquid aliphatic-substituted polysiloxane, containing in the molecule an average of from 1.9 to 2.5 aliphatic groups per silicon atom, and from 0.1 to 1 per cent of a saturated fatty acid containing 8 to 14 carbon atoms in the molecule. Suitable fatty acids are lauric, myristic, capric, caprylic, pelargonic, undecanoic, tridecanoic and 2-ethyl hexanoic acids. Suitable liquid aliphatic-substituted polysiloxanes may be prepared by the hydrolysis of aliphatic-substituted silanes, e.g. dialiphatic-substituted dihalogenosilanes, for instance, dimethyl dichlorosilane, followed by complete or partial condensation of the hydrolysis product.  They may also be prepared by hydrolysing mixtures of hydrolysable dialiphatic-substituted silanes either among themselves or with other hydrolysable silanes containing, for example, three aliphatic radicals substituted on the silicon atom, for instance, trimethyl chlorosilane.  The hydrolysable aliphatic-substituted silanes are those derivatives of SiH4 which contain hydrolysable groups or radicals, e.g. halogens, amino groups, alkoxy, aryloxy and acyloxy radicals, in addition to the aliphatic groups.  Examples of such aliphatic groups are alkyl radicals, e.g. methyl, ethyl, propyl, isopropyl and butyl and alkenyl radicals such as vinyl, allyl and methallyl.  If desired, the aliphatic groups may also contain substituents, for instance, halogens.  In examples, n-capric, lauric or myristic acid is added to a liquid methyl polysiloxane. Specifications 586,187, 586,188, 586,189 and 630,911 are referred to. The Specification as open to inspection under Sect. 91 refers to the use of proportions of saturated fatty acid in excess of 1 per cent, proportions up to 5 per cent being mentioned.  Liquid cycloaliphatic-substituted polysiloxanes derived from substituted silanes containing such alicyclic radicals as cyclopentyl or cyclohexyl may also be employed.  This subject-matter does not appear in the Specification as accepted.