Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
  • F16D69/00—Friction linings; Attachment thereof; Selection of coacting friction substances or surfaces
  • F16D69/02—Composition of linings ; Methods of manufacturing
  • F16D69/025—Compositions based on an organic binder
  • F16D69/026—Compositions based on an organic binder containing fibres

Definitions

• This invention relates to friction materials, and more preferably to friction materials of the kind used for brake pads, brake linings, clutch facings and similar uses.
• Friction materials of this kind are generally composed of a thermoset binder, an inorganic fibrous reinforcement and various fillers and other additives. These compositions are required to withstand severe operating temperatures and pressures under repeated application without failure or deterioration in friction properties and the fibrous reinforcement generally used is asbestos. Numerous proposals have been made of compositions containing other inorganic fibrous reinforcement but such materials have so far found limited commercial acceptance.
• an asbestos-free friction material composition comprises a thermosetting binder containing phenol-formaldehyde resin, a fibre based reinforcement including steel fibres and other fillers and additives characterised in that:-
• the steel fibres are fine, e.g. 0.125 mm diam., and with a length in the range 1 to 5 mm.
• the steel may be mild steel.
• the fibre-based reinforcement is a mixture of materials, one at least of which is staple steel fibre.
• Other reinforcing materials which may be included in the mixture in powder form include reinforcing fillers such as mica and wollastonite, and milled glass fibre.
• the thermoset binder includes a thermoset resin based on a phenol-formaldehyde resin but may also include a heat and chemical resistant vulcanised rubber, such as a nitrile rubber. Preferably a mixture of such materials is used of which the phenol-formaldehyde resin material constitutes at least half.
• a rubber When a rubber is used it may be incorporated into the friction material in the form of a powder but is preferably incorporated in the form of a solution in a suitable organic solvent and a vulcanising agent such as sulphur is also used.
• thermoset binder is preferably in the range 20 to 32% by volume of the friction material.
• various other materials may be included as fillers, friction and wear modifiers etc. the proportions of which can be varied to adjust the friction and other properties of the materials.
• the preferred additives are particulate fillers, more preferably a mixture of such materials and friction and wear modifying materials.
• the particulate fillers will' generally be present in an amount between 10 and 50% by volume and may include such fillers as barytes, whiting, silica etc.
• friction and wear modifiers are carbon, graphite, antimony trisulphide and molybdenum disulphide and metals, in a finely divided form.
• suitable metals are copper and tin. A mixture of such materials may be used, and the total amount of such materials may be up to 40% by volume.
• the friction materials of the present invention are particularly suited to be manufactured by a press-molding technique in which all the ingredients of the material are compounded together, the compounded mix disintegrated and (optionally dried) and then moulded into a component such as a brake pad in a die under pressure. The moulded component is then removed from the die and baked to cure the binder.
• the invention provides friction materials which do not contain asbestos, and yet have comparable properties to asbestos-based friction materials.
• Example 1 sample disc-brake pads were manufactured according to the formulation given below in Table I. The ingredients were initially compounded together, the nitrile rubber being introduced into the mixture as a powder and the compound was disintegrated and dried.
• the material was then moulded into pads under pressure in a die and the mouldings baked in an oven to cure the binder.
• sample pads produced were tested and found to have friction properties comparable to asbestos-containing materials.
• Sample disc-brake pads were manufactured according to the formulations given below in Table II. The ingredients were initially compounded together, the nitrile rubber being introduced into the mixture as a 15-20% solids content solution in trichloroethylene, and the phenol-formaldehyde resin as a 70% solids content solution in methylated spirits. The compound was disintegrated and dried and then moulded into pads under pressure in a die and the mouldings baked in an oven to cure the binder.
• Example 2 the reinforcement was a mixture of Steel Fibres and mica (as in Example 1) but in Example 3 the reinforcement was a mixture of the steel fibres and milled E Glass, the latter being a dust composed of very short lengths of milled glass fibre.
• the binder included equal amounts of rubber and resin.
• the wear of the material of Example 2 was as good as, or better than, most conventional materials of comparable friction level.
• the wear of the material of Example 3 was reasonable for the level of friction, although higher than that of the materials of Example 2.
• Example 2 The assembly shear strength of two pads of each material were measured, the values obtained for Example 2 being 16065 and 14755 KN/m 2 and those for Example 3 being 16134 and 15375 KN/m 2 .

Landscapes

• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Braking Arrangements (AREA)
• Manufacture Of Macromolecular Shaped Articles (AREA)
• Compositions Of Macromolecular Compounds (AREA)

Applications Claiming Priority (2)

Publications (2)

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• 1977
  • 1977-08-10 GB GB33458/77A patent/GB1604839A/en not_active Expired
• 1978
  • 1978-07-31 US US05/929,535 patent/US4273699A/en not_active Expired - Lifetime
  • 1978-08-01 IN IN566/DEL/78A patent/IN148770B/en unknown
  • 1978-08-02 ZA ZA00784379A patent/ZA784379B/xx unknown
  • 1978-08-08 EP EP78300258A patent/EP0000839B1/en not_active Expired
  • 1978-08-08 DE DE7878300258T patent/DE2860901D1/de not_active Expired
  • 1978-08-09 AU AU38754/78A patent/AU3875478A/en active Pending
  • 1978-08-09 IT IT50665/78A patent/IT1156900B/it active
  • 1978-08-09 BR BR7805104A patent/BR7805104A/pt unknown
  • 1978-08-10 DD DD78207214A patent/DD138076A5/xx unknown
  • 1978-08-10 SU SU782649254A patent/SU837328A3/ru active
  • 1978-08-10 CS CS785243A patent/CS216919B2/cs unknown
  • 1978-08-10 JP JP9774778A patent/JPS5434349A/ja active Pending
• 1980
  • 1980-05-14 US US06/149,697 patent/US4310452A/en not_active Expired - Lifetime

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