Rolling oil for aluminous metals

Improved rolling oil compositions are obtained by blending a petroleum base oil with a polymeric fatty acid, a fatty alcohol and lower alkyl ester of a fatty acid. These formulations are extremely effective for use in the cold rolling of aluminum and aluminum alloys.

BACKGROUND OF THE INVENTION 
(1) Field of the Invention 
This invention relates to the lubrication of aluminum and aluminum alloy 
surfaces during cold forming operations, such as cold rolling, and to 
rolling oil compositions suitable for such use. More particularly, this 
invention relates to improved rolling oil lubricant compositions having 
superior loadbearing (EP) properties which produce smooth uniform sheets 
free of surface defects, and which are non-staining and form a protective 
barrier on the surface of the metal. 
(2) Description of the Prior Art 
Lubricants are typically employed in cold forming processes to prevent 
damge to the surface of the metal and to generally facilitate the 
operation. It has been the general practice when cold rolling aluminum to 
apply a light petroleum-based oil, such as mineral oil, containing a small 
amount of an additive. These impart a number of desirable properties to 
the rolling oil but their primary function is to insure that sheets of 
uniform thickness and free from objectionable surface defects are 
obtained. A wide variety of lubricant compositions have been developed for 
this purpose but many of these formulations stain the metal immediately 
upon application or during the annealing operation. It would be highly 
advantageous, therefore, if rolling oil compositions were available for 
use with aluminum and aluminum alloys which exhibit excellent lubrication 
properties and do not produce undesirable surface stain. 
SUMMARY OF THE INVENTION 
I have now quite unexpectedly discovered improved lubricant compositions 
suitable for use as rolling oils for aluminous metals which produce 
bright, unstained metal sheet free of surface defects. In addition to 
their non-staining character, the rolling oil compositions of this 
invention also exhibit superior lubricating properties and provide a 
protective coating on the surface of the aluminum or aluminum alloy so 
that the surface of the metal is resistant to water staining during 
subsequent storage and/or shipment. 
The improved rolling oil lubrication compositions of this invention are 
comprised of a petroleum oil base stock containing from about 1 to 20, and 
more preferable 3 to 10, weight percent of an additive consisting of: 
(A) FROM ABOUT 25% TO 65% BY WEIGHT OF A POLYMERIC FATTY ACID AND 
PREFERABLY A DIBASIC ACID CONTAINING GREATER THAN 75% BY WEIGHT C.sub.36 
dibasic acid and having a maximum iodine value of 35; 
(B) FROM ABOUT 15% TO 45% BY WEIGHT OF A FATTY ALCOHOL HAVING 8 TO 20 
CARBON ATOMS AND MORE PREFERABLY A SATURATED ALCOHOL HAVING FROM 10 TO 18 
CARBON ATOMS, OR MIXTURES THEREOF; AND 
(C) FROM ABOUT 15% TO 45% BY WEIGHT OF A LOWER ALKYL ESTER OF A FATTY ACID 
HAVING FROM 12 TO 18 CARBON ATOMS AND MORE PREFERABLY A METHYL ESTER OF 
C.sub.14-18 fatty acids or mixtures of said fatty acids.

DETAILED DESCRIPTION 
The improved rolling oil compositions of this invention consist of a major 
proportion of a petroleum-based oil and a minor amount of an additive 
consisting of (a) a polymeric fatty acid, (b) a fatty alcohol having 8 to 
20 carbon atoms or mixture of said alcohols and (c) an alkyl ester of a 
C.sub.12-18 fatty acid or mixture thereof. 
A polymeric fatty acid is a necessary and essential component of the 
rolling oil compositions of this invention. Useful polymeric fatty acids 
are obtained by the polymerization of unsaturated monocarboxylic acids 
containing from 16 to 20 carbon atoms. Dimer acids obtained by the 
dimerization of oleic acid, linoleic acid or mixtures thereof (e.g. tall 
oil fatty acids) and which have as their principle component a C.sub.36 
dibasic acid are especially useful. Such C.sub.36 dibasic acids are 
commerically available under the trademark EMPOL.RTM. Dimer Acids. Dimer 
acids containing greater than 75% by weight and preferably more than 90% 
by weight, C.sub.36 dibasic acid and which have a maximum iodine value of 
35, and preferably not greater than 20, have been found to provide 
especially useful rolling oil compositions. Typically, in addition to the 
prescribed C.sub.36 dibasic acid content and iodine value, these dimer 
acids will have an acid value between about 180-215, saponification value 
from 190-205 and neutral equivalent of about 265-300. 
A fatty alcohol having 8-20 carbon atoms is included with the polymeric 
fatty acid. Fatty alcohols suitable for this purpose are aliphatic 
alcohols and are typically straight-chain, that is, contain no alkyl 
branching within the molecule. Suitable alcohols include but are not 
limited to nonyl alcohol, lauryl alcohol, myristyl, alcohol, cetyl 
alcohol, stearyl alcohol, oleyl alcohol, and linoleyl alcohol and mixtures 
thereof. Preferably, the fatty alcohols are saturated alcohols and have 
from 10-18 carbon atoms. Especially useful in view of their commerical 
availability are mixtures of said fatty alcohols. 
The alkyl ester is derived from the fatty acid having from 12 to 18 carbon 
atoms. Lower alkyl esters of these acids, that is, where the alkyl group 
contains from about 1-4 carbon atoms, are especially advantageous for the 
formulation of the rolling oil compositions of this invention. Methyl 
esters are particularly advantageous and especially useful are methyl 
esters of C.sub.14 and C.sub.18 fatty acids or mixtures of these fatty 
acids. Typically, the fatty acids will be saturated, however, unsaturation 
can be present in the fatty acid moiety without adversely affecting the 
desirable properties of the rolling oil composition. 
From about 25% to 65% by weight, and more preferably 30 to 60 weight 
percent, of the polymeric fatty acid is used to obtain the improved 
rolling oil compositions of this invention. These weight percentages are 
based on the total additive package and do not include the petroleum base 
oil. The fatty alcohol constitutes 15% to 45% by weight, and more usually 
20% to 40% by weight, of the rolling oil additive. The alkyl ester 
component in the additive mixture is present from about 15 to 45 weight 
percent but more usually will constitute from about 20 to 40 weight 
percent. 
If the above-described components are present in the prescribed weight 
ratios, a multi-functional additive which provides excellent lubrication 
and a high surface finish is obtained. Furthermore, it has quite 
unexpectedly been found that rolling oil compositions formulated with 
these additive packages do not produce oil staining upon application or 
during subsequent annealing operations or if some staining is observed it 
is insignificant. Even more surprisingly the surface of the so-treated 
aluminum or aluminum alloys are protected against water staining which can 
occur during storage or shipment. 
The three-component additive package consisting of the polymeric fatty 
acid, fatty alcohol and alkyl ester of a fatty acid is typically combined 
with a light petroleum base oil which serves as a diluent, facilitates 
application of the additive onto the metal surface and also imparts useful 
lubrication properties. Useful petroleum oils, which can be either 
aliphatic or contain aromatic hydrocarbons, will have 100.degree. F. 
viscosities of 20 to 100 SUS. More usually, these base oils will have 
100.degree. F. viscosities between 25 and 60 SUS. Typically, they have 
flash points above 115.degree. F. and more generally greater than 
175.degree. F. Hydrocarbon oils designated as mineral oils or mineral seal 
oils are especially useful for the preparation of multi-purpose rolling 
oil compositions of this invention. Synthetic hydrocarbon oils obtained by 
oligomerizing olefins having up to 20 carbon atoms in the presence of 
peroxide or Friedel-Crafts catalysts can also be employed. Additional 
additives such as stabilizers, fungicides, bacteriocides and the like can 
also be included in the rolling oil formulation. The concentration of the 
additive package in the hydrocarbon oil will range from about 1 to 20 
weight percent, however, the additive more usually is present from about 
3% to 10%. Using such concentrations rolling oil compositions exhibiting 
extremely desirable performance characteristics are obtained. 
The rolling oils of this invention are suitable for use with aluminum and a 
wide variety of aluminum alloys generally containing 80% by weight or more 
aluminum. The formulated oil can be applied to the surface of the metal 
employing conventional procedures such as dipping, brushing, spraying, 
wiping, coating with a roller, or the like. 
Typically, a rolling oil composition based on mineral oil or mineral seal 
oil containing from about 4 to 7 weight percent of an additive comprising 
C.sub.36 dimer acid, C.sub.10-18 saturated fatty alcohol and methyl ester 
of a C.sub.14-18 fatty acid will have the following properties: 
Acid Vaue: &lt;10 
210.degree. F. Viscosity: 0.5-2 Centistokes 
100.degree. F. Viscosity: 8-12 Centistokes 
Flash Point: &gt;260.degree. F. 
Fire Point: &gt;290.degree. F. 
Pour Point: -50.degree. F. or above 
The following examples and data illustrate the invention more fully, 
however, they are not intended as a limitation on the scope thereof. All 
parts and percentages are on a weight basis unless otherwise indicated. 
These examples illustrate the novel rolling formulations and the numerous 
variations possible therewith. The utility of these products with aluminum 
and aluminum alloys is also demonstrated. 
to demonstrate staining resistance 0.1 ml. of the rolling oil is placed in 
a small aluminum dish with 0.1 ml. of a 50/50 toluene-isopropanol solution 
and heated in a muffle furnace at 650.degree. F. for 30 minutes. The 
dishes are then visually examined and rated from 0 to 5 (0 indicates no 
stain; 5 indicates a heavy brownish/black stain). 
Water stain protection is measured by applying several drops of the rolling 
oil sample to a 3 inches .times. 6 inches solvent-washed panel stampled 
from rolled aluminum sheet. The oil is uniformly spread over the entire 
surface of the panel and the weight adjusted by wiping with a soft tissue 
so that approximately 0.0075 grams of the oil remain. The test panels are 
then perpendicularly mounted 0.5 inch from the sidearm of a 500 ml. 
stoppered suction flask. Steam is generated by vigorously boiling water in 
the flask and the steam is directed onto the panel through the side-arm 
for a period of five minutes. The panel is then removed, allowed to dry 
and visually rated for water stain development using a 0 to 5 rating 
system (0 indicates no stain; 5 indicates a water stain having a diameter 
greater than 1 inch). 
Lubricating properties of the formulations are determined using a modified 
Falex wear test procedure. A standard steel pin and aluminum V-block 
assembly are employed. Wear readings are taken at 100, 500, 750, 1000, 
1250 and 1500 pound loadings. The sum of these readings are reported as 
the "units of wear". The test is then completed by continuously increasing 
the load by engaging the ratchet until failure and this is reported as the 
"EP" value for the sample. 
A rolling oil composition was obtained by blending 50 parts EMPOL.RTM. 1012 
Dimer Acid (87% C.sub.36 dibasic acid, 3% C.sub.54 tribasic acid and 10% 
monobasic acid) with 30 parts methyl stearante and 20 parts mixed 
saturated fatty alcohols containing 85% lauryl alcohol. The resulting 
blend had an acid value 89.7, hydroxyl value 55.0, 210.degree. F. 
viscosity 8.5 centistokes, 100.degree. F. viscosity 58.4 centistokes, 
flask point 315.degree. F., cloud point 50.degree. F., pour point 
35.degree. F. and specific gravity (25.degree. C.) 0.887. A 4% solution of 
the blend was prepared with 40 SUS mineral seal oil and the rolling oil 
compositions evaluated for lubricity, water stain and oil stain in 
accordance with the above-described procedures. Two hundred and 
forty-seven units wear was recorded in the Falex test and in the EP phase 
of the test the product withstood testing up to 3,000 lbs. No staining was 
observed upon application of the formulation onto freshly rolled aluminum 
sheet. Even after heating at 650.degree. F. for 30 minutes, oil staining 
was negligible - 1 on the rating scale. The oil also provided excellent 
water stain protection as evidenced by the water stain rating of only 1. 
The three-component additive blend was similarly blended at a 6% level in 
mineral oil. A slight decrease in lubricity (256 units wear with an EP 
rating of 2,750 lbs.) was observed but excellent water stain protection 
and resistance to oil stain was still obtained. 
Thirty parts methyl stearate and 20 parts mixed saturated fatty alcohols 
containing predominantly lauryl alcohol were combined with 50 parts of a 
dibasic acid (96% C.sub.36 dibasic acid, 3% C.sub.54 trimer acid and 1% 
monobasic acid) having an iodine value of approximately 13. This product 
was blended at three and six percent levels with 40 SUS mineral seal oil 
to obtain lubricants useful for cold rolling aluminum. The rolling oil 
composition exhibited excellent lubricity in the Falex test, gave 
negligible oil stain when heated at 650.degree. F. for 30 minutes and 
provided an effective hydrophobic barrier on the surface of the metal. 
Forty parts EMPOL.RTM. 1010 Dimer Acid containing 97% by weight C.sub.36 
dimer acid, 40 parts lauryl alcohol and 20 parts methyl oleate were 
blended and a 6% solution prepared therefrom with 40 SUS mineral seal oil. 
The resulting lubricating composition gave an average stain rating of 1.5 
in duplicate tests conducted at 650.degree. C. for 30 minutes. The oil 
also provided a continuous protective barrier on the surface of the 
aluminum so that the sheet was effectively protected against the formation 
of water stain during storage and shipment even under conditions of high 
humidity. The water stain rating for sheets treated with the oil was only 
1. In addition to the aforementioned properties, the rolling oil 
composition exhibited superior lubricity even under high loads. When 
methyl stearate was substituted for all or a portion of the methyl oleate 
in this formulation the lubricating properties were enhanced without 
detracting from the other desirable properties of the rolling oil. 
Fifty parts dimer acid having a maximum iodine value of 35 and containing 
87% by weight C.sub.36 dimer acid was blended with 20 parts lauryl alcohol 
and 30 parts of a mixture of methyl stearate and methyl palmitate. A six 
percent solution was prepared with mineral seal oil. The lubricant 
solution exhibited superior lubricating properties in the Falex test and 
gave excellent results on a single pass rolling mill with aluminum sheet. 
A high degree of reduction was obtained using this formulation while 
obtaining a uniform sheet free from surface defects and surface stain. 
Even after annealing no undesirable oil stain was evident on the sheet. 
The rolled sheet thus obtained was also resistant to development of water 
stain in the steam test. A stain rating of 1 was obtained with the 4% 
rolling oil solution and when the additive level was increased to 6%, no 
water staining was observed. The composition also provided effective 
lubrication in other metal working operations involving aluminum and 
aluminum alloys.