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Low friction, abrasion-resistant bearing materialsRelated Patent Categories: Synthetic Resins Or Natural Rubbers -- Part Of The Class 520 Series, Natural Rubber Compositions Having Nonreactive Materials (dnrm) Other Than: Carbon, Silicon Dioxide, Glass Titanium Dioxide, Water, Hydrocarbon, Halohydrocarbon, Ethylenically Unsaturated Reactant Admixed With A Preformed Reaction Product Derived From: (a) At Least One Polycarboxylic Acid, Ester, Or Anhydride; (b) At Least One Polyhydroxy Compound; And (c) At Least One Fatty Acid Glycerol Ester, Or A Fatty Acid Or Salt Derived From A Naturally Occurring Glyceride, Tall Oil, Or A Tall Oil Fatty Acid, At Least One Solid Polymer Derived From Ethylenic Reactants Only, With Polycarboxylic Acid Or Derivative And A Polyol At Least One Of Which Is Saturated, A Condensate Or Solid Polymer Thereof; Or With Solid Polymer Derived From At Least One Polycarboxylic Acid Or Derivative And At Least One Polyol Wherein At Least One The Reactants Forming The Solid Polymer Is Saturated, Polycarboxylic Acid Or Derivative Or Polyol Contains An Atom Other Than C, H, Or O; Or Wherein A Polycarboxylic Acid Or Derivative Or Polyol Or Condensate Thereof Is Reacted With A Reactant Containing Atoms Other Than C, H, Or O Prior To Blending With The Solid Polymer; Or Wherein A Coreactant With The Polycarboxylic Acid Or Derivative Or Polyol Contains An Atom Other Than C, H, Or OLow friction, abrasion-resistant bearing materials description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070123652, Low friction, abrasion-resistant bearing materials. Brief Patent Description - Full Patent Description - Patent Application Claims
RELATED APPLICATIONS [0001] The present application is a continuation application of U.S. patent application Ser. No. 10/783,004, filed Feb. 19, 2004, allowed. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] This invention relates to improved bearing materials comprising PTFE. These bearing materials are suitable for a variety of applications in, for example, the aerospace, industrial, medical and agricultural industries, [0004] 2. Description of Prior Art [0005] It is known in the art to utilize self-lubricating bearings and materials to provide reduced friction and reduced wear in a range of load-bearing applications. These bearings are expected to withstand damage during use and installation. Further, the self-lubricating bearings are typically subject during use to a variety of conditions such as heat and pressure, as well as chemical attack from a variety of substances. [0006] The choice of a bearing material to meet a given need depends on the specific conditions and performance required and tends to be a complex engineering task in view of the many parameters which must be taken into account. A representative list of conditions that are to be taken into account might include, for example, velocity, pressure (including amount of load, direction of load, and speed of impact of load), dynamic friction, static friction, temperature, chemical exposure, lubrication, dimensional stability, geometrical fit, nature of the counter surface, and susceptibility to fluid lubrication erosion ("cavitation"). [0007] Conventional friction management materials and systems include roller bearings, ball bearings, and plain bearings. In the plain bearing arena, many different forms of plastics bearing materials comprising a plastic matrix having various fillers and/or porous bonding layers are known. Many of them include polytetrafluoroethylene (PTFE), which is widely known for its low coefficient of friction. PTFE also provides the benefit of being stable under a wide range of temperatures and is inert to most chemicals. However, the wear characteristics, excessive creep and the bond strength to substrates of PTFE are poor, so different supporting materials are incorporated with the PTFE in various ways. Some of these supporting materials include metals, which are believed to draw heat away from the system and thus result in improved wear. In addition, some metals, such as lead, are thought to contribute to the lubricity of the system. However, the science of mechanisms in these systems is not fully understood. [0008] Many products have been made available in this field, and a variety of patents exist, directed to bearing and other friction-reducing materials incorporating polytetrafluoroethylene (PTFE). For example, many bearing materials incorporate PTFE floc, or short fibers, which are incorporated into a resin material and spray coated onto a substrate. U.S. Pat. No. 3,806,216 describes materials which are representative of this type of construction. In another form, PTFE film has been skived from a solid, full-density PTFE block, then laminated to fabric or metal backers and bonded together with various resin systems. U.S. Pat. No. 4,238,137, to Furchak, describes materials which are representative of this type of construction. PTFE fibers formed into woven or non-woven sheets or fabrics, which are then impregnated with resin (e.g., U.S. Pat. No. 4,074,512) and/or laminated to an epoxy or other backing material (e.g., U.S. Pat. No. 3,950,599) have also been used as bearing materials. PTFE floc or particles have been incorporated into a thermoplastic material, then molded and/or machined into bearings. Further, PTFE dispersions, sometimes combined with fillers, have been dried or otherwise bonded on a sintered metal layer/metal substrate or other metal substrate (e.g., U.S. Pat. Nos. 2,689,380; 5,498,654 and 6,548,188 and Japanese Unexamined (Kokai) Patent Application No. 3-121135). [0009] U.S. Pat. No. 5,792,525 to Fuhr et al., teaches bearing parts formed from one or more layers of a densified expanded PTFE material which can be machined or otherwise formed to the desired shape. Such materials exhibit good resistance to creep under a load; however, the wear limitations of such materials limit their use in many demanding bearing applications. [0010] As can be seen from the wide range of PTFE-containing materials described, some solution has been developed for virtually every bearing application; however, the market continues to need lower friction, lower wear systems that enable lower power consumption and longer bearing life. In addition, environmental concerns regarding lead have resulted in a search for lead-free materials that perform as well as, or better than, the current lead-containing materials. [0011] Accordingly, a need has existed in the field of self-lubricated bearing materials and bearing articles for new bearings exhibiting enhanced wear resistance and low friction relative to conventionally available materials. SUMMARY OF THE INVENTION [0012] This invention is a unique wear resistant composite bearing material that solves many of the current problems of the self lubricated bearings market. The bearing material comprises monolithic, or continuous, porous polytetrafluoroethylene materials combined with other polymer materials in a unique configuration which has heretofore not been achieved in the art. [0013] Numerous forms of porous, monolithic PTFE exist and are suitable in bearing materials of this invention. For example, U.S. Pat. No. 5,677,031, to Allan et al., and U.S. Pat. No. 6,019,920, to Clough, are directed to monolithic porous PTFE structures comprising an open network of fused granular PTFE particles that define a tortuous network of voids throughout the structure. Another example of a suitable porous, monolithic PTFE suitable for a bearing material of the present invention is expanded PTFE, characterized by a structure of nodes interconnected by fibrils, and the appearance of this node and fibril structure can vary depending on whether the material is expanded in one direction (e.g., uni-axial) or in multiple directions (e.g., bi-axial, multi-axial, etc.). Other suitable forms of porous, monolithic PTFE materials suitable in the present invention may include monolithic PTFE sheets which are perforated or otherwise modified to create porosity and other reticulated PTFE forms. [0014] It has been surprisingly discovered that these porous, monolithic PTFE materials, whether in the form of membranes, rods, tubes or other suitable forms, can be imbibed with polymer resins comprising thermosetting resins or thermoplastic resins, such as described in more detail herein, and bearings made from the resulting imbibed structures exhibit improved wear resistance over that which has been achieved in the prior art. [0015] Polymer resin materials suitable for imbibing into the ePTFE structures can include a wide range of thermosetting resins including, but not limited to, epoxies and their hybrids, phenolics, polyesters, acrylates, polyimides, polyurethanes, cyanate esters, bismaleimide, polybenimidazole, and the like. The preferred thermosetting resins are those which have high thermal stability (e.g., epoxies, polyamide-imide, cyanate esters and phenolic resins, etc.). In addition, many thermoplastic resins including, but not limited to, polyetheretherketone (PEEK), polyetherketone (PEK), polyaryletherketone (PAEK), liquid crystal polymer (LCP), polyimide (PI), polyetherimide (PEI), acetals, acrylics, fluoropolymers, polyamides, polycarbonates, polyolefins, polyphenylene oxides, polyesters, polystyrenes, polysulfones, polyethersulfones, polyphenylene sulfide, polyvinyl chloride, and the like, may also be imbibed into the ePTFE structures to form low friction, wear-resistant composites. [0016] Depending on the desired application and performance of the resulting composite material, the polymer resin volume percent of solids and volume ratio of solids (PTFE to polymer resin) may vary significantly. Materials with resin volume percents ranging from 40% to 80% have resulted in suitable composites in accordance with the present invention; however, higher volume percents and lower volume percents are also contemplated to be within the scope of suitable composites for the low friction, abrasion-resistant materials of this invention. [0017] Depending on the particular performance desired, the imbibed ePTFE composite materials may also incorporate one or more fillers to alter or tailor the performance to meet a specific performance requirement. For example, a filler such as graphite or boron nitride may be included to lower the composite coefficient of friction (COF). Further, fillers such as aluminum oxide, titanium dioxide, glass fiber, or carbon may be used to improve wear resistance, even if such fillers might tend to increase the COF. DESCRIPTION OF THE DRAWINGS [0018] The foregoing summary, as well as the following detailed description of the invention, will be better understood when read in conjunction with the appended drawings. For purposes of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings: [0019] FIGS. 1 and 2 are schematic representations of the rotating test specimen and the test fixture, respectively, for performing wear testing on the materials of the invention; [0020] FIG. 3 is a graph of the load vs. compression for the test fixture shown in FIG. 1 during wear testing. Continue reading about Low friction, abrasion-resistant bearing materials... Full patent description for Low friction, abrasion-resistant bearing materials Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Low friction, abrasion-resistant bearing materials patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Low friction, abrasion-resistant bearing materials or other areas of interest. ### Previous Patent Application: Thermoplastic elastomer composition and molded article Next Patent Application: Polymerizable compositions in non-flowable forms Industry Class: Synthetic resins or natural rubbers -- part of the class 520 series ### FreshPatents.com Support Thank you for viewing the Low friction, abrasion-resistant bearing materials patent info. 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