GB2185996A

GB2185996A - Lubricating composition comprising polybutene

Info

Publication number: GB2185996A
Application number: GB08600559A
Authority: GB
Inventors: David J Neadle; Terry W Dicken
Original assignee: SMALLMAN LUBRICANTS Ltd
Current assignee: SMALLMAN LUBRICANTS Ltd
Priority date: 1986-01-10
Filing date: 1986-01-10
Publication date: 1987-08-05
Also published as: GB2185996B; GB8600559D0

Abstract

A composition comprises a volatile solvent in which there is dissolved and/or dispersed a mixture of lubricants, wherein said mixture includes a major proportion by weight of polybutene and a minor proportion by weight of a fat and/or a metal soap.

Description

SPECIFICATION Lubricating composition The present invention relates to a lubricating composition suitable for use as a lubricant at an interface between a body of aluminium and means for def- orming that body under high pressure. By high pressure, we mean a pressure such as is used in extrusion or cold forging of aiuminium, in contra-distinction to the relatively low pressures encountered in bending sheet aluminium.

According to the invention, there is provided a composition comprising a volatile solvent in which there is dissolved and/or dispersed a mixture of lubricants, wherein said mixture includes a major proportion by weight of polybutene and a minor proportion by weight of a fat and/or a metal soap.

By a volatile solvent, we mean a solvent having a boiling point not greater than 1500Cand preferably not greater than 1 00 C. The composition contains a sufficient proportion of the solvent to facilitate preparation of an homogeneous composition and to facilitate application of the composition by brush or by spray to the surface of a metal billet. After applica- tion ofthe composition to the surface of the billet, evaporation ofthesolventwill occur. Accordingly, the proportion of the solvent in the composition does not have particular relevance to the ability of the composition to function as a lubricant in working ofthe billet.

The thickness of the lubricant on a face of the billet' may be built up by successive applications of the composition, the layer of composition applied being left exposed after each successive application to permit evaporation of the solvent. The solvent is preferably a chlorinated hydrocarbon.

The polybutene used in the composition preferably has a high molecularweight. Since the polybutene is not a single compound, the molecular weight must be an average value. Furthermore, prior to admixture with the other components of the composition, the polybutene has a high viscosity. Two or more grades of polybutene may be incorporated together in the composition. Preferably, the polybutene or at least a portion thereof, in a case where more than one grade of polybutene is used, is non liquid at 1 8"C. By this, we mean that the polybutene does not flow freely under its own weight.

The average molecular mass (number average) of the polybutene preferably exceeds 2,5000 and preferably exceeds 3,000. There is preferably included in the compostion a polybutene mixture having a viscosity of 98.9"C which exceeds 5,000 cSt and may exceed 20,000 cSt or even exceed 40,000 cSt.

From 65% to 85% by weight of the mixture of lubricants is preferably polybutene. The remaining proportion ofthe mixture of lubricants may be comprised entirely by one or more metal soaps, by one or more fats, or by a mixture of these. The preferred composition comprises both metal soaps and fats. We include in the term "fats" synthetic esters and we preferto use a blend of natural fats and synthetic esters.

The proportion of this blend in the composition may be somewhat less than the proportion of metal soap. A mixture of metal soap, for example calcium stearate and sodium stearate, may be employed.

The invention also embraces use of the composition to lubricate the interface between a body of aluminium and meansfordeformingthatbody under high pressure.

According to a further aspect of the invention, there is provided a method of preparing a lubricant for use at an interface between a body of aluminium and means for deforming that body under high pressure, the method comprising the steps of dispersing in a volatile, organic solvent a metal soap and then adding polybutene gradually, the polybutene being at a temperature substantially greater than that of the solvent and the solution being stirred during the addition of the polybutene. The temperature of the polybutene which is added to the dispersion may be greaterthan the boiling point of the solvent. The polybutene is preferably added gradually over a period in excess of fifteen minutes.

For use, the solution is applied to the surface of a body of metal which isto be formed orto the surface of a metal tool to be used in forming a body of metal and evaporation of the solvent is permitted after the solution has been applied to that surface and before the lubricant is subjected to high pressure byworking ofthe body of metal.

Afat may be incorporated in the dispersion of soap in the solvent, prior to addition of the polybutene.

Examples of compositions in accordance with the present invention are prepared by dispersing one or more metal soaps in a volatile, organic solvent which is at ambient temperature. Typically, a combination of calcium stearate and sodium stearate in the ratio 6.5 to 1.5, by weight is used. There is then added to the dispersion a blend of fats, typically a blend of natural fats and synthetic esters. The volume of this blend is used is typically such as to provide 5%, by volume, of the final composition.

The volume of solvent used is typically 47.5% of the total volume of the final composition. The solvent is preferably a halogenated hydrocarbon or a mixture of halogenated hydrocarbons. The solvent sold underthetrade mark "GENCLENE" is a suitable solvent. This solvent boils at720C.

A quantity of a first grade of polybutene, namely that sold underthe designation NHYVIS 200" by B.P.

Chemicals Limited, is heated to a temperature within the range 1 20"C to 150"C and is slowly added to the dispersion whilst the latter is stirred. A quantity of a further grade of polybutene, namely that sold under the designation "HWIS 2000" is also heated to a temperature within the same range and is added slowly to the solution. The temperature of the solution rises somewhat, butthe rate of addition of polybutene is restricted to avoid the temperature of the solution rising above 60 C. Typically, addition of the polybutene extends over a period within the range 30to 60 minutes. The different grades of polybutene may be added in succession or together. The resulting composition is sealed in containers for storage and transportation.

Thetotalvolumeofandthetotalweightofpoly- butene used exceeds the aggregate volume of the stearates and fats and the aggregate weight of the stearatesandfats respectively. Typically, the total volume of polybutene is within the range 35% to 50% of the volume of the final composition. More specif ically, the volume of "HWIS 200" used may be 22% and the volume of the "HYVIS 2000" used may be 21.5% of the volume of the final composition.

The composition has been found to be especially useful in the lubrication of aluminium billetswhich are extruded by placing each billet in an elongated die which is closed at one end and introducing a mandrel into the die from the opposite end thereof to exert high pressure on the billet and cause extrusion ofthe aluminium along the surface ofthe mandrel.

This process is typically used in the manufacture of cylindersforcontaining gases under pressure. The composition is applied to one end face of the billet, whilst the billet is outside the die and with thatface presented upwardly. More than one application of the composition to that face may be made before the billet is placed in the due.

The features disclosed in the foregoing description, orthe accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, or a class or group of substances or compositions, as appropriate, may, separately or any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

1. A composition comprising a volatile solvent in which there is dissolved and/or dispersed a mixture of lubricants, wherein said mixture includes a major proportion by weight of polybutene and a minor proportion by weight of a fat and/or a metal soap.

2. A composition according to Claim 1 wherein the polybutene, or at least a portion thereof, is non liquid at 18 C, priorto mixingwiththeothercon- stituents of the composition.

3. A composition according to Claim 2 wherein the average molecular mass of the polybutene exceeds 2,500.

4. A composition according to any preceding Claim wherein from 65% to 85% by weight of the mixture of lubricants is polybutene.

5. A composition according to any preceding Claim wherein the mixture of lubricants comprises both a metal soap and a fat.

6. Use of a composition as defined in any preceding Claim as a lubricant at the interface between a body of aluminium andmeansfordeformingthat body under high pressure.

8. A method of preparing a lubricantfor use atan interface between a body of aluminium and means for deforming that body under high pressure, the method comprising the steps of dispersing in a volatile, organic solvent, a metal soap and then adding polybutene gradually, the polybutene being atatemperature substantially greater than that ofthe solvent and the solution being stirred during the addition of the polybutene.

9. A method according to Claim 8wherein a fat is incorporated in the dispersion of soap in the solvent, priorto addition of the polybutene.

10. A method according to Claim 8 or Claim 9 wherein the solution is permitted to cool to ambient temperature and is then applied to the surface of a body of metal, the solvent is permitted to evaporate and leave a surface layer of lubricant on the body of metal.

11. Any novel feature or novel combination of features disclosed herein.