US 4,735,982 A · Thermoplastic-rubber polymer alloys and method for producing the same

Abstract

A thermoplastic-rubber polymer alloy contains a tough, wear resistant low friction thermoplastic such as ultra high molecular weight polyethylene, a cured rubber compound such as nitrile rubber, an a lubricant such as graphite in effective amounts to produce a composition which has good wet and dry friction and wear properties. The ultra high molecular weight polyethylene is typically utilized in a sufficient amount so as to form a continuous phase with the thermoset rubber being present as particles dispersed throughout the polyethylene as a discontinuous phase. The polymer alloy is made by dry blending the thermoplastic compound with ground thermoset rubber whereby the rubber is coated, heating and mixing the composition to above the glass transition temperature of the thermoplastic compound and subsequently cooling under pressure. The alloy can be easily transfer molded because of the lubricating action of the heated, softened plastic. The alloy is ideally suited for use as a hard bearing material due to its low coefficient of friction and low wear rate.

Claims17

Dependent claims

A thermoplastic-rubber polymer alloy, comprising;

a particulate cured rubber compound having a particle size of 35 mesh or smaller, said cured rubber compound being a low friction, water resistant compound,
an ultra high molecular weight polyethylene polymer, said ultra high molecular weight polyethylene polymer having a weight average molecular weight of at least 2.5 million the amount of said ultra high molecular weight polyethylene polymer being an effective amount to form a continuous phase in the polymer alloy and to coat, said rubber particles, and
a non abrasive lubricant, the amount of said lubricant being an effective amount to impart lubricating properties to said alloy.

A process for forming a thermoplastic-rubber polymer alloy comprising the steps of:

dry mixing (a) cured rubber particles having a particle size of 35 mesh or smaller, said cured rubber compound being a low friction, water resistant compound, (b) an ultra high molecular weight polyethylene polymer having a weight average molecular weight of at least 2.5 million, and (c) a solid non-abrasive lubricant in amount effective to impart lubricating properties to said alloy, said ultra high molecular weight polyethylene polymer having a breakaway coefficient of static friction at 0 RPM of 0.25 or less, the amount of said ultra high molecular weight polyethylene polymer being an effective amount to form a continuous phase and to coat said rubber particles,
heating said mixture to a temperature above the glass transition temperature of said ultra high molecular weight polyethylene polymer, and
cooling said heated mixture under pressure and forming the polymer alloy, said cooling pressure being 600 PSI or greater.

Dependencies are inferred from the claim text.

Thermoplastic-rubber polymer alloys and method for producing the same

Life of this patent

Thermoplastic-rubber polymer alloys and method for producing the same

Life of this patent

Abstract

Claims17