EP1123963A1

EP1123963A1 - Non-staining lubricating composition

Info

Publication number: EP1123963A1
Application number: EP00400346A
Authority: EP
Inventors: Francis Prince; Jean-Yves Claire
Original assignee: Mobil Oil Francaise SA
Current assignee: Mobil Oil Francaise SA
Priority date: 2000-02-08
Filing date: 2000-02-08
Publication date: 2001-08-16

Abstract

The present invention relates to a non-staining lubricating composition for use in metal working machines, comprising, based on the total weight of the composition, from 1 to 99,5% of a benzene alkylate.

The invention also relates to a process for rolling stainless steel, copper, copper alloys, aluminium and aluminium alloys and to the use of the non-staining lubricating composition to lubricate the moving or turning parts of a stainless steel, copper, copper alloys, aluminium and aluminium alloys rolling mill.

Description

The present invention relates to a non-staining lubricating composition for use in metal working machines and to a process for rolling stainless steel, copper, copper alloys, aluminium and aluminium alloys.
Lubricating compositions are used in various machines like mills, in which they serve to lubricate metal parts which are in contact and have a relative movement, like for instance bearings.
When used in mills, the lubricating compositions sometimes come into contact with the rolled metal, which usually leads to metal staining and in some instances causes the rolled metal sheets to stick together.
International patent application n° WO 91/06619 discloses the use of a composition comprising a saturated aliphatic monohydric alcohol having from 14 to 18 carbon atoms and optionally a polybutene, petroleum jelly or butyl stearate, as a solid lubricant in the cold working of a metal workpiece.
It has also been proposed in British patent applications No. 964,268 and No. 1,109,304, US patents No. 4,488,979, No. 4,228,217, No. 2,899,390, and No. 2,621,159 to use polyisobutenes as alternatives to mineral oils in metal working, where staining must be avoided.
However, these compositions or compounds do not have satisfactory viscosity-shearing characteristics (the viscosity being highly influenced by the shearing rate but decreasing sharply at a given value of the shearing rate) and/or non-sticking properties.
The invention therefore provides a non-staining lubricating composition having high non-staining properties whilst having high lubricity and non-sticking properties.
Thus, the invention provides a non-staining lubricating composition comprising, based on the total weight of the composition, from 1 to 99,5%, preferably from 70 to 99%, of a benzene alkylate.
The invention further provides a process for preparing the non-staining lubricating composition of the invention.
The invention also provides a process for lubricating the moving or turning metal parts of a stainless steel, copper, copper alloys, aluminium and aluminium alloys rolling mill, comprising applying an effective amount of the composition of the invention to said moving or turning parts.
In addition, the invention provides the use of the non-staining lubricating composition of the invention to lubricate the moving or turning parts of a stainless steel, copper, copper alloys, aluminium and aluminium alloys rolling mill.
The invention is now disclosed in more details in the following specification and in reference to the accompanying drawings in which :
Figure 1 is a photograph showing the results of a rolling test performed with a lubricant of the prior art;
Figure 2 is a photograph showing the results of a rolling test performed with the lubricating composition of the invention.
The benzene alkylate of the non-staining lubricating composition of the invention may be a dialkyl benzene wherein the alkyl groups are identical or different from each other and have from 12 to 40 carbon atoms.
Examples of benzene alkylates include benzene 1,2 didodecane, benzene 1,4 dicetane, benzene 1-nonadecane, and benzene 4-eicosane.
The preferred benzene alkylates are benzene dialkylates, wherein the alkyl groups have from 24 to 34 carbon atoms. Most preferred is a mixture comprising :

50 weight percent of a benzene dialkylate wherein both alkyl groups have 24 carbon atoms; and
50 weight percent of a benzene dialkylate wherein both alkyl groups have 34 carbon atoms.

The benzene alkylate typically has a viscosity from 5 to 1000 cSt at 40°C, preferably from 22 to 460 cSt at 40°C.
The non-staining lubricating composition of the invention may comprise conventional additives, such as surfactants, coupling agents or cosurfactants, friction reducing agents or lubricity agents, corrosion inhibitors or anti-oxidants, extreme-pressure and anti-wear agents, anti-foaming agents, anti-rust agents.
Examples of anti-foaming agents are silicone based, especially polydimethylsiloxane.
Examples of corrosion inhibitors are hindered phenols and zinc dialkyldithiophosphates (ZDDP).
Examples of extreme-pressure and anti-wear agents are dilauryl phosphate, didodecyl phosphite, trialkylphosphate such as tri(2-ethylhexyl)phosphate, tricresylphosphate (TCP), zinc dialkyl(or diaryl)dithiophosphates (ZDDP), phospho-sulphurized fatty oils, zinc dialkyldithiocarbamate), mercaptobenzothiazole, sulphurized fatty oils, sulphurized terpenes, sulphurized oleic acid, alkyl and aryl polysulphides, sulphurized sperm oil, sulphurized mineral oil, sulphur chloride treated fatty oils, chlornaphta xanthate, cetyl chloride, chlorinated paraffinic oils, chlorinated paraffin wax sulphides, chlorinated paraffin wax, and zinc dialkyl(or diaryl)dithiophosphates (ZDDP), tricresylphosphate (TCP), trixylylphosphate (TXP), dilauryl phosphate, respectively.
Examples of corrosion inhibitors or anti-oxidants are radical scavengers such as phenolic antioxidants (sterically hindered), aminic antioxidants, organo-copper salts, hydroperoxides decomposers, butylated hydroxytoluene.
Examples of anti-rust agents are amine derivative of alkenyl succinic anhydride.
Further elements on base oils and additives can be found in "Chemistry And Technology Of Lubricants", R.M. Mortier and S.T. Orszulik, VCH Publishers, Inc, 1992, in "Lubrication Fundamentals", J. George Wills, Ed. Marcel Dekker, Ind, 1980.
The non-staining lubricating composition of the invention is prepared by blending the benzene alkylate and the other ingredients, preferably whilst stirring and controlling the temperature so that is does not exceed 50°C, and more preferably, 40°C. Any mixing device can be used.
The non-staining lubricating composition of the invention can be used on various metal working machines, to lubricate moving or turning parts, like bearings, ball bearing, gears, etc.
Examples of metal working machines include mills, for example, any type of rolling mill, be it reversible or not, of the Sendzimir type (e.g. 1-2, 1-2-3, 1-2-3-4), or of Z-high type (e.g. 2-high, 4-high, 6-high), be it a reversible mill, a tandem mill, etc..
The non-staining lubricating composition of the invention is particularly adapted to be used in cold and hot rolling processes, e.g. stainless steel cold rolling mills or aluminium hot tandem mills.
The non-staining lubricating composition of the invention can be used in the metal working of various metals, namely stainless steel, copper, copper alloys, aluminium and aluminium alloys.
The following example illustrates the invention without limiting it. All parts and ratios are given by weight, unless otherwise noted.

Example

A composition is prepared by mixing the ingredients of Table 1 in the order in which they appear in this table. The temperature is maintained at a maximum of 40°C (this ensures a complete dissolution and homogeneisation of the ingredients without impairing the properties of the composition).

Ingredients	Content (wt%)
Mixture of 50 wt % of C₂₄ and 50 wt % of C₃₄ dialkylbenzenes (220 cSt at 40°C)	98.19
Zinc dithiophosphate (anti-wear agent)	0.70
Trioctyl phosphate ester (extreme-pressure additive)	0.60
4,4' methylenebis (2,6 ditertiobutyl phenol) (anti-oxidant)	0.20
Ditertiobutyl paracresol (anti-oxidant)	0.20
Succinimic acid derivatives (corrion inhibitor)	0.05
Polyoxyethylene alcohol (surfactant)	0.05
Polysiloxane derivatives diluted in kerosene (defoamant)	0.01

The characteristics of the composition of Table 1 are set out in Table 2.

Property	Unit	Method	Typical characteristics
Colour	-	ISO 2049	0.5
Density at 15°C	g/ml	ASTM D 1298	0.876
Pour point	°C	ISO 3016	-30
Kinematic viscosity at 40°C	CSt	ISO 3104	220
Water separability	Min	ASTM D 1401	LT 10
Copper corrosion 3 hours, 180°C	-	ASTM D 130	1A
Shear stability, viscosity loss	%	CEC L14A78	0.0
FZG Load support failure stage	-	DIN 51354	11
Rust Test A	-	ASTM D665	Pass

EXPERIMENTAL TESTING

The experimental testing is carried out by simulating the contamination of a rolling mill oil with the lubricating composition, in order to observe the effects on the rolled metal sheet.
Staining tests are performed using a rolling oil based on a kerosene cut having a viscosity of 1.8 cSt at 40°C and containing first, 10% of a lubricant of the prior art, and then 10% of the lubricating composition of the invention.

The selected lubricant of the prior art having a viscosity of 220 cSt at 40°C has the composition set out in the following Table 3 :

Ingredients	Content (wt%)
Paraffinic base oils blend (viscosity about 150 cSt at 40°C)	97.3
Polyisobutylene (kinematic viscosity at 100°C : 2800 cSt)	1,0
Polymethacrylate derivative, (pour point depressant)	0.2
Bis methylene dibutyl dithiocarbamate (anti-wear, extreme-pressure agent)	1.0
Petroleum sodium sulfate (corrosion inhibitor)	0.5

The staining tests are performed in the following way : aluminium metal discoloration is observed after 15 minutes at 300 °C, in an oxidative atmosphere.
Figure 1 is a photograph showing the results of the test performed with the lubricant of the prior art.
Figure 2 is a photograph showing the results of the test performed with the lubricant of the invention.
It appears from theses figures that the metal is less stained by the lubricating composition of the invention than by the lubricant of the prior art, which demonstrates a surface quality improvement of the rolled metal strip.
The resistance to shearing according to CEC L-14-A-78 was found to be significantly improved for the oil composition of the invention.
Lubricity according to the "FZG" (Forschungstellefür Zahnräder und Getriebe) test DIN 51354 Part 1 is significantly improved with the oil composition of the invention (FZG failure load of 11 whereas a FZG failure load of 10 was obtained with the oil composition of the prior art).
A viscosity loss of 10 to 20% is generally observed for oil compositions of the prior art.

Claims

Non-staining lubricating composition comprising, based on the total weight of the composition, from 1 to 99,5% of a benzene alkylate.
Non-staining lubricating composition according to claim 1, comprising, based on the total weight of the composition, from 70 to 99% of said benzene alkylate.
Non-staining lubricating composition according to claim 1 or 2, wherein the benzene alkylate is a dialkyl benzene wherein each alkyl group has from 12 to 40 carbon atoms.
Non-staining lubricating composition according to any one of claims 1 to 3, wherein the benzene alkylate is selected from the group consisting of benzene 1,2 didodecane, benzene 1,4 dicetane, benzene 1-nonadecane, and benzene 4-eicosane.
Non-staining lubricating composition according to any one of claims 1 to 3, wherein the benzene alkylate is a benzene dialkylate, wherein the alkyl groups have from 24 to 34 carbon atoms.
Non-staining lubricating composition according to claim 5, wherein the benzene alkylate is a mixture comprising :

50 weight percent of a benzene dialkylate wherein both alkyl groups have 24 carbon atoms; and

50 weight percent of a benzene dialkylate wherein both alkyl groups have 34 carbon atoms.
Non-staining lubricating composition according to any one of claims 1 to 6, in which the benzene alkylate has a viscosity comprised between 5 and 1000 cSt at 40°C, preferably between 22 and 460 cSt at 40°C.
Non-staining lubricating composition according to any one of claims 1 to 7, further comprising at least one ingredient selected from the group consisting of surfactants, coupling agents, cosurfactants, friction reducing agents, lubricity agents, corrosion inhibitors, anti-oxidants, extreme-pressure agents, anti-wear agents, bactericides, fungicides, anti-foaming agents and anti-rust agents.
Process for the preparation of a non-staining lubricating composition according to claim 8, comprising blending the benzene alkylate and the other ingredients under stirring or with any mixing device.
Process according to claim 9, wherein the blending is carried out at a temperature which does not exceed 50°C, preferably 40°C.
Process for lubricating the moving or turning metal parts of a stainless steel, copper, copper alloys, aluminium and aluminium alloys rolling mill, comprising applying an effective amount of the composition according to any one of claims 1 to 8 to said moving or turning parts.
Use of the non-staining lubricating composition according to any one of claims 1 to 8 to lubricate the moving or turning parts of a stainless steel, copper, copper alloys, aluminium and aluminium alloys rolling mill.