| 摘要 |
An electrically conducting polymer thickened grease composition is provided, comprising 1) a lubricating base oil 2) a polymer thickener 3) an electrically conducting component 4) further additives known per se, characterised in that the polymeric thickener comprises a mixture of (1) a (co- or homo-)polymer of propylene with a weight average molecular weight > 200.000 and (2) a (co- or homo-)polymer of propylene with a weight average molecular weight < 100.000. . The electrically conducting component is preferably chosen from metal containing additives, especially organo metallic/organo bismuth compounds; anti-static agents, or electrically conducting solids, such as soft metal particles, silver, copper, graphite, bismuth or niobium (IV) sulfide. The grease composition can conduct electricity through the parts of a roller bearing, not only under static conditions, but also during use; this makes the greases especially suited for use in roller bearings with rotating electrical contacts, such as described in SKF's US patent 5 139 425. The grease can further reduce or prevent the build-up of static electricity and spark formation in roller bearings. The grease is prepared by mixing/dissolving the melted polymer thickener with/in a lubricating base oil and incorporating the electrically conducting component and the further additives. After that, the grease composition is cooled from the mixing temperature to room temperature, preferably by "quenching", i.e. rapid cooling within around 30 seconds. After that the grease can be worked to the required consistency. The invention further relates to the use of a polymeric thickener in a preparation of an electrically conducting lubricant grease composition. |
