DD251988A1 - PTFE-containing lubricant with reduced creep tendency - Google Patents

Abstract

The invention relates to a PTFE-containing lubricant with reduced creep and is mainly in the Feingeraetetechnik, such as on bearings mechanical-optical devices, used where high surface pressures or point loads occur. The aim of the invention is a lubricant which can be used in a wide temperature range while ensuring consistently good lubricating properties and effective suppression of creeping. The task of finding a dispersing agent which inhibits the agglomeration of the PTFE powder, the coagulation of the lubricant emulsion and the creep of the lubricant, with the use of fluorine-containing surface-active compounds, such as vH Polyfluorcanbonsaeure the general formula H (C2F4) n COOH with n1 ... 10 and their esters H (C2F4) n-COOR with alcohols of the chain lengths RC6H13 ... C18H37 and n1 ... 10 solved.

Description

Field of application of the invention

The invention relates to a lubricant with high lubricity and is used where high surface pressures occur at lubrication points and therefore the spreading of the lubricant must be prevented to ensure the device function. The lubricant is intended in particular for the fine equipment technology, such as for bearings of mechanical-optical devices.

Characteristic of the known technical solutions

In the technical and patent literature, a number of technical solutions for the production of lubricants for special applications are published. For example, it is known that the lubricating properties of consistent lubricants can be improved by adding PTFE fine powder. U.S. Patent No. 4,333,840 discloses a hybrid PTFE gun lubricant specifically designed for use with handguns which, in addition to reducing friction and thus wear, prevents rapid soiling. The hybrid lubricant is composed of a relatively high viscosity carrier oil in which the microfine PTFE powder is stably dispersed and a larger amount of a synthetic low viscosity oil mixed together. To stabilize the dispersants, a fluorine-containing surfactant is added to the hybrid lubricant. The PTFE particles impregnate the microscopic pits in the metal surfaces and a protective layer with high lubricity over a wide temperature range is formed. A particularly disadvantageous effect of this hybrid lubricant that, due to its very special application for handguns, a lubricant is required with low viscosity, need to be made in terms of spreading no requirements. The hybrid lubricant thus does not meet the essential requirement for a reduced creep.

DE-PS 4 465 607 describes the preparation of stable dispersions of PTFE powder with particle sizes of 1 to 200 μm in lubricating oils. These lubricant compositions, which have a high lubricity due to the addition of PTFE powder, are intended for use in crankshaft housings.

The lubricant is not subject to any requirements for spreading and coagulating the emulsion in this field of application because the lubricant is contained in a closed housing and coagulation of the emulsion is prevented by the moving parts. This lubricant is thus not for lubrication points, where due to high surface pressures or Puriktbelastungen a reduced creep of the lubricant is required, can be used.

Object of the invention

The aim of the invention is to develop a lubricant which ensures consistently good lubricating properties under extreme conditions of use with respect to the ambient temperature and at the same time suppresses the creep of the lubricant as possible.

Essence of the invention

The invention has for its object to find a dispersion medium which prevents the agglomeration of the microfine PTFE powder and in conjunction with a tailored to the conditions of use, base oil forms a non-coagulating emulsion, which is characterized by a reduced creep.

This object is achieved with the PTFE-containing reduced creep lubricant in which the lubricity-enhancing PTFE powder having particle sizes of 0.1 to 0.5 μπη is dispersed by a dispersing agent in a base lubricant such as mineral oil and synthetic oil is achieved in that the dispersant used to stabilize the PTFE particles, ω-H-polyfluorocarboxylic acids of the general formula H (C ₂ F ₄ J _n COOH with η = 1 ... 10 and their esters H (C ₂ F ₄ J _n COOR with alcohols of chain length R = C ₆ H _{] 3} ... C ₁₈ H ₃₇ and η = 1 ... 10 are used.

With the invention, a lubricant has been developed which, by the addition of microfine PTFE powder, has good lubricating properties, which are equally ensured by the selection of a corresponding mineral or synthetic oil as a base lubricant at a wide temperature range. Through the use of ω-H-polyfluorocarboxylic acid as a dispersant can be achieved in conjunction with the base lubricant at the same time a stable dispersion and a suppression of creep of the lubricant.

embodiment

The invention will be described below with reference to an embodiment.

The PTFE-containing lubricant with reduced creep consists of PTFE powder with grain sizes of 0.1 to 0.5 μm, which is incorporated in a dispersion medium and mixed to improve the lubricating effect as the base lubricant. Base lubricants here are silicone oils, ester oils or mixtures thereof. The dispersants used are co-H-polyfluorocarboxylic acids of the general formula H (C ₂ F ₄ ) _n COOH with η = 1 to 10 and their esters H (C ₂ F ₄ J _n COOR with alcohols of the chain lengths R = C ₆ H ₁₃ ... C ₁₈ H ₃₇ and η = 1 to 10. In addition to the stated synthetic oils, ie silicone oils, for example methyl, ethyl or phenylmethylsilicone oils, and ester oil, for example trimethylolpropane or pentaerythritol esters of carboxylic acids with chain length C ₄ H ₉ to C ₆ H ₁₃ , phthalic acid esters and dicarboxylic acid esters with alcohols of chain length C ₈ H ₁₇ to C ₁₃ H ₂₇ and 2-ethylhexyl alcohol wherein the number of methyl groups of the dicarboxylic acids may be 2 to 6, mineral oils are also suitable as base lubricants.

The preparation of the PTFE powder with particle sizes of 0.1 to 0.5 μπι is advantageously carried out by irradiation of PTFE waste by means of γ-rays.

The PTFE-containing lubricant can be used where at lubrication points high surface pressures or point loads occur and therefore the spreading of the lubricant must be prevented in order to ensure the device function. In particular, the lubricant for the Feingerätetechnik, such as for bearings of mechanical-optical devices, provided.

The particular advantage of this lubricant is that with the use of ω-H-polyfluorocarboxylic acids or their esters as dispersants, the agglomeration of the PTFE particles and at the same time the creep of the lubricant emulsion are prevented. This dispersant enables the preparation of stable, non-coagulating emulsions. The use of Polyfluorcarbonsäureestern is particularly suitable in combination with ester oils as a base lubricant, which has been shown that the use of uncleaned reaction products of Polyfluorcarbonsäureester an even better, the creeping inhibiting. Effect is achievable. The applicability of the lubricant, which achieves a higher lubricity due to the addition of PTFE powder, is possible due to the use of base lubricants in a temperature range. For example, very high demands can be made on silicone oils in terms of the viscosity-temperature behavior.

Claims (1)

Invention claim: 1. PTFE-containing lubricant with reduced creep, in which the improvement of the lubricity PTFE powder used, with particle sizes of 0.1 to 0.5 μηι dispersed by a dispersing agent in a base lubricant, such as mineral oil and synthetic oil, characterized in that, as dispersing agent, for stabilizing the PTFE particles, ω-H-polyfluorocarboxylic acids of the general formula H (C ₂ F ₄ ) _n COOH with η = 1 to 10 and their esters H (C ₂ H ₄ ) _n COOR Alcohols of chain length R = C ₆ H ₁₃ ... C ₁₈ H ₃₇ and η = 1 ... 10 are used.