Patent GB-899659-A (GB)
Title: Improvements in or relating to lubricating moving metallic parts
IPC: C08G77/24
Filed: 1959-06-01
Abstract: A method of lubricating moving metallic parts comprises maintaining between the bearing surfaces of the parts a liquid polymer consisting essentially of units of the general formula RCH2CH2(R1)SiO, where R is a perfluoroalkyl radical containing 1-10 carbon atoms and R1 is a phenyl radical or an alkyl radical containing 1-4 carbon atoms.  The liquid polymer may be thickened to a grease particularly with finely-divided materials such as bentonite, carbon black, diatomaceous earth, fume silica, silica aerogel, silica xerogel, phthalocyanine or a metal phthalocyanine.  In the examples, the liquid polymer employed is a trifluoropropyl methyl siloxane polymer endblocked with both trimethylsiloxy units and hydroxyl groups.  In some of the examples, this polymer is thickened with (a) copper phthalocyanine or (b) a mixture of silica xerogel, dimethyl polysiloxane, boric acid and pentaerythritol.  Tests are described in which the lubricants of the examples are compared with a liquid phenyl methyl polysiloxane consisting of 80 mol. per cent dimethylsiloxane units, 9 mol. per cent of trimethylsiloxane units and 11 mol. per cent of phenyl methyl siloxane units, thickened or not with lithium stearate.  Specifications 832,487, 832,489 and 899,657 are referred to.ALSO:A liquid polymer employed as a lubricant (see Group III) consists essentially of units of the general formula RCH2CH2(R1)SiO, where R is a perfluoroalkyl radical containing 1-10 carbon atoms and R1 is a phenyl radical or an alkyl radical containing 1-4 carbon atoms.  The liquid polymer may be thickened to a grease particularly with finely-divided materials such as bentonite, carbon black, diatomaceous earth, fume silica, silica aerogel, silica xerogel, phthalocyanine or a metal phthalocyanine. The liquid polymer may be prepared by polymerizing 3,3,3-trifluoropropyl methyl cyclotrisiloxane (which may be obtained as described in Specification 832,487) in the presence of an acid or alkaline catalyst at 50 DEG -100 DEG C., for example as described in Specification 832,489.  Polymerization in the absence of end-blocking units yields hydroxy end-blocked linear polymers.  However, the polymerization may be conducted in the presence of a hexaorganodisiloxane (using sulphuric acid, sodium hydroxide or the siloxanol salt of sodium hydroxide as catalyst), whereupon 3,3,3-trifluoropropyl methyl polysiloxane liquids end-blocked with both triorganosiloxy groups and hydroxy groups are obtained. Where a catalyst of the perfluoroalkyl sulphonic acid type is used (as described in Specification 899,657), linear polymers containing no hydroxyl groups are obtained.  In an example, a liquid trifluoropropyl methyl siloxane end-blocked with both trimethylsiloxy units and hydroxyl groups is obtained by polymerizing trifluoropropyl methyl cyclotrisiloxane in the presence of hexamethyl disiloxane, using sulphuric acid as catalyst.  In further examples, this polymer is thickened with (a) copper phthalocyanine or (b) a mixture of silica xerogel, dimethyl polysiloxanes, boric acid and pentaerythritol.