Patent GB-865395-A (GB)
Title: Improvements in low-friction bearing elements
IPC: F16C33/20
Filed: 1957-04-29
Abstract: 865,395. Laminates. WHITE, C. S. April 29, 1957 [May 9, 1956], No. 13589/57. Class 140. [Also in Groups XXVI and XXXIV] A laminated bearing element comprises a backing member, a bearing surface formed by a cloth comprising threads of low-friction fluorocarbon resin and a barrier layer bonded between the backing member and the low friction material, the barrier layer being impervious to the material of the backing member so as to prevent such material penetrating between the threads of the low fricton material and thus impairing the low friction properties of the bearing surface. The fluorocarbon resin may be a polymer of an ethylenically unsaturated perfluorocarbon or a chloro-, bromo-, or nitro-substituted fluorocarbon, e.g. polytetrafluoroethylene or polymonochlorotriofluoroethylene. The cloth may be a matted, unwoven fabric or a woven fabric, consisting solely of threads of fluorocarbon resin, or may comprise fluorocarbon resin threads and more easily bondable threads woven together as described in Specification 845,547 in such a way that the fluorocarbon resin threads appear on one face and the interwoven more easily bondable threads on the other face where they unite with the barrier layer. Alternatively, the fabric may be woven from threads containing fluorocarbon fibres and more easily bondable fibres. The more easily bondable threads may be nylon or cotton and the barrier layer may be formed by the fusion of a layer of nylon threads interwoven with the fluorocarbon resin threads. The backing may be natural rubber, butyl rubber, polyvinyl chloride or a laminate of phenol- or urea-aldehyde resin, polyester, polyurethane, natural or synthetic rubber. The barrier layer may be a layer of rubber which forms a barrier when cured, or may comprise a curable synthetic resin or a mixture of an extender resin, e.g. a vinyl resin, a phenol-formaldehyde resin, an amino aldehyde resin, or an acrylic resin, with a fluorocarbon resin and, if desired, a monomeric ethylenically unsaturated fluorocarbon, or a partly polymerized fluorocarbon resin. The barrier layer may be applied as a coating to one side of a glass cloth which is bonded to the fluorocarbon resin cloth by means of the coating, the glass cloth side of the resulting laminate being bonded to a backing using another adhesive, if required, e.g. polyvinyl chloride when the backing is of polyvinyl chloride. Friction elements in the form of discs, which may be slightly domed, washers, and hollow cylinders lined with the fluorocarbon resin cloth, are described. A seal may have a cylindrical portion 37, Fig. 6, of resilient natural or butyl rubber, which is to engage a movable rod, and a flange 36 to engage the wall of a housing about a hole through which the rod extends. A sleeve is bonded to the inner surface of the cylindrical portion 36 having a layer of woven fluorocarbon resin threads 39 interwoven with a layer 41 of nylon threads, the nylon thread layer having been matted by heat and pressure to form a barrier layer. In forming a similarly shaped seal made of polyvinyl chloride, a primer coat of one of the extender resins mentioned above is applied to the inner cylindrical surface and cured, a barrier coat of a mixture of extender resin and fluorocarbon resin is applied and a fluorocarbon resin cloth is then bonded to the backing using heat and pressure.