Fluorinated greases
AssigneeAusimont S.p.A.
InventorsAlba Chittofrati, Paolo Lazzari, Luca Caluso
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Abstract
Fluorinated greases comprising (by weight): 15%-50% polytetrafluoroethylene or tetrafluoroethylene copolymers with other ethylenically unsaturated monomers; 30%-84.5% perfluoropolyether oil having a viscosity comprised between 20 and 4000 cSt at 20.degree. C.; 0.5%-10% surfactant or dispersant having perfluoropolyether or perfluoroalkylic chain; 0%-10% of an anticorrosion and/or antiwear additive, such that the (per)fluoropolymer particles based on TFE or their aggregates have average sizes lower than the micron and show improved diameter WEAR values.
Claims17
Fluorinated greases comprising at least:
- 15%-50% by weight of a polytetrafluoroethylene or tetrafluoroethylene copolymers with other ethylenically unsaturated monomers totally or partially fluorinated;
- 30%-84.5% by weight of perfluoropolyether oil having a viscosity comprised between 20 and 4000 cSt at 20.degree. C.;
- 0.5%-10% by weight of surfactant or dispersant having perfluoropolyether or perfluoroalkylic chain;
- 0%-10% by weight of an anticorrosion and/or antiwear additive,
- said fluorinated greases being obtained by a process comprising at least the following steps:
- a) obtaining a TFE-based (perfluoropolymer by polymerization in an aqueous phase;
- b) adding surfactants in an amount from 50 to 500 mg per gram of polymer to the TFE-based (per)fluoropolymer in the aqueous phase;
- c) adding to the aqueous phase of b) a perfluoropolyether oil having a viscosity lower than 5 cSt at 25.degree. C. and a boiling point not greater than 150.degree. C., or to a fluorocarbon with a boiling point lower than 150.degree. C., so that the ratio by weight of polymer/oil is lower than 0.5;
- d) adding a perfluoropolyether oil having a viscosity between 20 and 4000 cSt at 20.degree. C. in amounts such as to obtain in the final grease a polymer percentage by weight of between 15% and 50%;
- e) evaporating completely under vacuum the low boiling components at a temperature between 50.degree. C. and 90.degree. C.
- such that the (per)fluoropolymer particles based on TFE or their aggregates have average sizes smaller than a micron.
A process for preparing fluorinated greases comprising at least the following steps:
- a) obtaining a TFE-based (per)fluoropolymer by polymerization in an aqueous phase;
- b) adding surfactants in an amount from 50 to 500 mg per gram of polymer to the TFE-based (per)fluoropolymer in the aqueous phase;
- c) adding to the aqueous phase of b) a perfluoropolyether oil having a viscosity lower than 5 cSt at 25.degree. C. and a boiling point not greater than 150.degree. C., or to a fluorocarbon with a boiling point lower than 150.degree. C., so that the ratio by weight of polymer/oil is lower than 0.5;
- d) adding a perfluoropolyether oil having a viscosity between 20 and 4000 cSt at 20.degree. C. in amounts such as to obtain in the final grease a polymer percentage by weight of between 15% and 50%;
- e) evaporating completely under vacuum the low boiling components at a temperature between 50.degree. C. and 90.degree. C.
Dependencies are inferred from the claim text.