| 摘要 |
A composition of acetal resin infused with one or more polyglycols to impart an improved tribological property. The composition is produced by mixing a powdered or granulated polyoxymethylene homopolymer (or copolymer) in the range from about 75% to about 95% by weight, with from about 25 to about 5% by weight of one or more polyglycols. Examples disclosed include compositions in which the single polyglycol comprises a polyethylene glycol, an ethylene oxide-propylene glycol monobutyl ether, a diethylene glycol n-butyl ether, an ethylene oxide-propylene oxide polyglycol, and a propylene glycol monobutyl ether. Preferably, if an oil soluble polyglycol is added, either a polyethylene glycol or a propylene glycol monobutyl ether is included to serve as a compatibilizer for the oil soluble polyglycol. One preferred embodiment includes 80% by weight of the powdered acetal, 14% by weight of the polyethylene glycol, which serves as the compatibilizer, and 3% by weight of the ethylene oxide-propylene glycol monobutyl ether, which is the oil soluble polyglycol. This example exhibits a substantially reduced friction coefficient and a much greater contact stress withstand level than acetal resin that does not include a polyglycol. The composition is prepared by mixing the components in an extrusion machine or in a torque rheometer while applying heat. A strand of the composition is thus extruded and cut into pellets suitable for injection molding into various types of desired objects.
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