Technical Field
[0001] The present invention relates to a lubricating oil composition for metal working,
particularly to a lubricating oil composition which comprises a specific type of straight
chain olefin, alcohol and the like, and which has excellent detergency (removability)
of abrasion dust produced in metal working of aluminum and aluminum alloy.
Background Art
[0002] Generally, when straight chain-α-olefin is used as a lubricant in metal working such
as plastic working (rolling or drawing), cutting, and grinding, working dust (abrasion
dust) is adhered to the surface of a worked material after the working is finished.
This results in deterioration of quality of a worked product and has unfavorable influence
on the following working process.
[0003] For example, when an aluminum plate is rolled with the straight chain-α-olefin, aluminum
abrasion dust is adhered to a rolled plate. If the rolled plate is annealed without
removing such dust, annealing irregularity occurs very frequently. In case an aluminum
foil is rolled by the use of the straight chain-α-olefin, there is afear that pinholes
are made on the aluminum foil because of the presence of abrasion dust. Likewise,
abrasion dust is adhered to a worked material in cutting and grinding processes to
cause various troubles.
Disclosure of the Invention
[0004] In view of the above, the present inventors have earnestly pursued the studies in
order to develop a lubricating oil for metal working which has excellent removability
(detergency) of abrasion dust produced in metal working such as plastic working, cutting,
and grinding performed on various kinds of metal such as aluminum, steel and brass,
and alloys thereof, which is excellent in workability and capable of finishing the
surface of a worked material in an excellent condition.
[0005] As a result, it has been found out that the above-mentioned object is accomplished
when a base oil containing straight chain olefin having 6 to 40 carbon atoms is used
together with alcohol, glycol, polyalkylene glycol, or fatty acid.
[0006] The present invention is accomplished on the basis of the findings mentioned above.
[0007] According to the present invention, there is provided a lubricating oil composition
for metal working, comprising (a) a base oil containing, as an essential component,
straight chain olefin having 6 to 40 carbon atoms and (b) at least one member of compounds
selected from the group consisting of alcohol, glycol, polyalkylene glycol, a derivative
of polyalkylene glycol, and fatty acid.
[0008] According to the present invention, there is also provided a lubricating oil composition
for metal working, comprising (a) the above-mentioned base oil and (c) at least one
member of compounds selected from the group consisting of phenolic compounds and amine
compounds.
Best Mode for Carrying out the Invention
[0009] In the composition according to the present invention, the straight chain olefin
constituting the base oil of the component (a) has 6 to 40 carbon atoms as described
above. The straight chain olefin with the carbon atoms of less than 6 is undesirable
because of a low flash point. If the number of carbon atoms is more than 40, the practical
use is difficult because of a solid state. Furthermore, there become difficult the
mixing with and the dissolving in mineral oil, synthetic oil, and other additives.
In addition, the straight chain olefin having more than 40 carbon atoms is not popular
and is difficult to be available. Among many kinds of the straight chain olefin, the
composition having one double bond in a molecule and 6 to 30 carbon atoms is preferable.
In particular, α-olefin (namely, n-α-olefin) having 12 to 30 carbon atoms are most
preferable.
[0010] Specifically, examples for the straight chain olefin may include 1-octene, 1-decene,
1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicocene, or mixtures thereof.
The straight chain olefin can be produced by various methods. For example, there may
be used ethylene oligomer obtained by polymerization of ethylene in an ordinary method.
[0011] According to the present invention, the above-mentioned straight chain olefin can
be used alone as the base oil of the component (a). Alternatively, mineral oil and/or
synthetic oil may be used together with the straight chain olefin. Water may also
be added. Mineral oil and synthetic oil to be added have usually a kinematic viscosity
of 0.5 to 500 cSt at a temperature of 40 °C, preferably, 0.5 to 30 cSt. V arious kinds
of mineral oil can be used, for example, distillate oil obtained through atmospheric
distillation of paraffinic crude oil, intermediate crude oil, or naphthenic crude
oil, or through vacuum distillation of residual oil in atmospheric distillation. Alternatively,
there may be used refined-oils obtained by refining the distillate oil in a usual
method, such as solvent refining, hydrogenation refining, dewax treating, and clay
treating. When such mineral oil is mixed with the above-mentioned straight chain olefin,
the resultant lubricating oil has an improved oxidation stability.
[0012] As synthetic oil, there may be used various types of olefin other than the above-mentioned
straight chain olefin (for example, branched chain olefin such as polybutene and polypropylene),
and hydrogenated product of such olefin. In particular, polybutene having low molecular
weight, polypropylene having low molecular weight, and α-olefin oligomer having 8
to 14 carbon atoms are preferable. When such synthetic oil is mixed with the above-mentioned
straight chain olefin, the resultant lubricating oil emits less odor during its use
so as to improve working environment. Further, degreasing ability on the surface of
a worked product is improved.
[0013] In case the mineral oil or the synthetic oil is mixed with the above-mentioned straight
chain olefin to constitute the base oil of the component (a), the amount of the straight
chain olefin is usually at least 3% by weight, preferably 5 to 60% by weight, while
the amount of the mineral oil and/or the synthetic oil is at most 97% by weight, preferably,
95 to 40% by weight, although no specific limitation is given to the mixing ratio.
[0014] When water is used instead of the mineral oil or the synthetic oil, the lubricating
oil of an emulsion type is obtained in which the straight chain olefin is dispersed
in water. According to the present invention, the lubricating oil of this type can
be used.
[0015] Then, as the component (b) in the composition according to the present invention,
there is used one member selected from the group consisting of alcohol, glycol, polyalkylene
glycol, a derivative of polyalkylene glycol, and fatty acid, or a combination of two
or more members.
[0016] As alcohol, various alcohols may be used, and among them, aliphatic alcohol is preferable.
Branched chain saturated or unsaturated aliphatic alcohol having 6 to 40 carbon atoms
(especially 8 to 30 carbon atoms), or straight chain saturated or unsaturated aliphatic
alcohol having 6 to 20 carbon atoms (especially 8 to 18 carbon atoms) is more preferable.
The alcohol having less than 6 carbon atoms is rapidly consumed due to evaporation
or splashing during its use and thus is economically disadvantageous. Branched chain
alcohol having more than 40 carbon atoms or straight chain alcohol having more than
20 carbon atoms is sometimes undesirable since it may be insoluble in the base oil
of the component (a).
[0017] Examples for such alcohol may include octyl (2-ethylhexyl) alcohol, decyl alcohol,
lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, eicosyl alcohol,
oleyl alcohol, isostearyl alcohol, oxoalcohol, and the like. The amount of the alcohol
is not limited, but it is suitable to use 0.05 to 50% by weight, preferably, 0.1 to
20% by weight, based on total amount of the composition.
[0018] As to glycol, various kinds of glycol may be used. Generally, there is used glycol
having 2 to 6 carbon atoms, for example, ethylene glycol, propylene glycol, trimethylene
glycol, 1,4-butanediol, 1,5-pentanediol, and the like. The amount of glycol is usually
0.05 to 50 % by weight, preferably, 0.1 to 20% by weight, based on the total amount
of the composition, which is similar to that of the above-mentioned alcohol. Furthermore,
there are various kinds of polyalkylene glycol or derivatives thereof. Among them,
the compound which is represented by the following general formula (I) is preferable.
R¹-O(R²-O)
n-R³ (I)
(In the formula, R¹ and R³ individually denotes a hydrogen atom, an alkyl group having
1 to 20 carbon atoms, an C₇-C₂₄- alkyl-substituted phenyl group, or a phenyl group;
and R² denotes an ethylene group, a propylene group, or a butylene group; n is an
integer of 2 to 50.)
[0019] More specifically, poly(n=6)ethyleneglycol-monobutylether, poly(n=5)propyleneglycol-monononylether,
poly(n=10)ethyleneglycol-dipropylether, and the like may be used. Glycerol derivative
of polyethylene glycol or fatty acid ester of polyethylene glycol can also be used
besides the compound given by the above-mentioned general formula (I). The amount
of glycol is usually 0.05 to 50% by weight, preferably 0.1 to 20% by weight, based
on the total amount of the composition, which is similar to that of the above-mentioned
alcohol.
[0020] As fatty acid, there are used straight/branched chain saturated/unsaturated fatty
acid having 6 to 40 carbon atoms (preferably 8 to 20 carbon atoms). There is a risk
that fatty acid having less than 6 carbon atoms are rapidly consumed due to evaporation
or splashing during its use, while fatty acid having more than 40 carbon atoms is
sometimes insoluble in the base oil of the component (a). Examples for such fatty
acid may include caprylic acid, capric acid, lauric acid, myristic acid, palmitic
acid, stearic acid, arachic acid, behenic acid, isostearic acid, undecylenic acid,
oleic acid, linoleic acid, linolenic acid, arachidonic acid, and the like. The amount
of fatty acid is usually 0.05 to 1.0% by weight, based on the total amount of the
composition. If the amount of fatty acid exceeds 1.0% by weight, the anti-stain ability
in annealing is unfavorably deteriorated.
[0021] As described, the composition according to the present invention comprises the above-mentioned
components (a) and (b). Instead of the component (b) or, alternatively, in addition
to the components (a) and (b), it is possible to blend the component (c) comprising
at least one compound selected from the group consisting of phenolic compounds and
amine compounds.
[0022] Various kinds of phenolic compounds can be used. Generally, the phenolic compound
represented by the following general formula (II) or (III) is used.
![](https://data.epo.org/publication-server/image?imagePath=1992/20/DOC/EPNWA1/EP91908465NWA1/imgb0001)
(In the formula, each of R⁴ and R⁵ denotes an alkyl group having 1 to 8 carbon atoms,
and each of R⁶ and R⁷ denotes a hydrogen atom or an alkyl group having 1 to 6 carbon
atoms.) Specifically, 2,6-di-tert-butyl-4-metylphenol (DBPC), 2,6-di-tert-butyl-4-ethylphenol,
2,2'-methylenebis (4-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-tert-butylphenol),
and the like are preferable.
[0023] As amine compounds, there are used various amine compounds, and it is suitable to
employ usually the compounds represented by the following general formula (IV) or
(V):
![](https://data.epo.org/publication-server/image?imagePath=1992/20/DOC/EPNWA1/EP91908465NWA1/imgb0002)
(In the formula, each of R⁸ and R¹¹ denotes a hydrogen atom or an alkyl group having
1 to 10 carbon atoms, each of R⁹ and R¹⁰ denotes an alkyl group having 1 to 20 carbon
atoms, and each of R¹² to R¹⁴ denotes a hydrogen atom or an alkyl group having 1 to
20 carbon atoms.)
[0024] Specifically, di-p-octyldiphenylamine, di-p-butyldiphenylamine, di-p-nonyldiphenylamine,
phenyl-α-naphthylamine, phenyl-β-naphtylamine, and the like are preferable.
[0025] The amount of the component (c) is preferably not less than 0.1% by weight, more
preferably 0.1 to 2.0% by weight, based on the total amount of the composition.
[0026] If desired, a suitable amount of an oiliness agent, an extreme-pressure agent, a
rust inhibitor, a corrosion inhibitor, a defoaming agent, or the like may be blended
with the composition according to the present invention.
Examples
[0027] Then, more detailed description will be made regarding the present invention with
reference to examples and comparative examples.
Examples 1 to 12 and Comparative Examples 1 to 3
[0028] The following rolling test was carried out by the use of lubricating oil for rolling
which has the composition shown in Table 1
Rolling Test (Aluminum Plate Rolling)
[0029] A JIS A 5052 H16 aluminum plate (a coiled plate having a thickness of 1.2 mm and
a width of 60 mm) was prepared as a material to be rolled. With each lubricating oil
for rolling, the plate was rolled by a four-stage rolling mill having a work roll
diameter of 135 mm at a rolling speed of 100 m/min. under forward tensions of 170
kgf and 400 kgf. The rolling process was carried out in such a manner that the reduction
was stepwise increased per 20 m length during one pass as 50.0→ 54.2→ 58.3→ 60.8→
63.3→ 65.8→ 68.3 (%). As to the plate having a thickness of 0.38 mm (a draft of 68.3
%) after the rolling process (after seven passes), the rolling load was measured.
Abrasion dust detergency and anti-stain ability were evaluated by the following methods.
(a) Evaluation Method for Abrasion Dust Detergency
(Tape Test Method)
[0030] A cellophane tape was stuck onto the surface of the aluminum plate after rolling
so as to pick up abrasion dust adhering thereto. Then, the tape was applied on a white
paper sheet to visually determine a degree of contamination by abrasion dust. Thus,
the detergency for abrasion dust adhering to the surface of the aluminum plate was
evaluated. The results thus obtained are shown in Table 1.
(b) Evaluation Method for Anti-stain Ability in Annealing
[0032] The aluminum plate after rolling was cut into piece having a short length of 10 cm.
The stack of several tens of the cut pieces were fixed by a thick steel plate and
annealed in a small-size annealing furnace.
[0033] The heating process in the annealing furnace comprises the step of: heating in an
air atmosphere with a temperature rising rate of 5 °C/min. until the temperature reaches
330 °C; holding for 30 minutes; and cooling. After completion of the heating process,
a degree of occurrence of annealing stains on the annealed plate was visually determined.
Thus, the anti-stain ability was evaluated. The results are shown in Table 1.
![](https://data.epo.org/publication-server/image?imagePath=1992/20/DOC/EPNWA1/EP91908465NWA1/imgb0004)
Examples 13 and 14 and Comparative Examples 4 and 5
[0034] The following cutting test was carried out by the use of lubricating oil for cutting
which has the composition shown in Table 2.
Cutting Test (Cutting for End Face of Cylinder)
[0035] A cylindrical aluminum alloy material (AC-4A-T6) having a diameter of 80 mm was prepared
as a material to be cut. The aluminum alloy material was cut to form an end face by
the use of a cutting tool (cemented carbide P20) under the cutting condition that
a cutting depth (t) is 1 mm and a feed rate (f) is 0.1 mm/revolution.
[0036] After the cutting, the surface roughness (R
max) of the cut end face was measured while the surface thereof was observed. The results
are shown in Table 2.
![](https://data.epo.org/publication-server/image?imagePath=1992/20/DOC/EPNWA1/EP91908465NWA1/imgb0005)
Industrial Applicability
[0037] As described above, by the use of a lubricating oil composition according to the
present invention, abrasion dust detergency is improved in metal working (plastic
working such as rolling, drawing, blanking, drawing, cold forging; cutting; and grinding)
for various kinds of metals and alloys thereof while anti-stain ability in annealing
of a worked material is improved.
[0038] Accordingly, a lubricating oil composition according to the present invention is
widely and effectively used as a metal working oil in plastic working, cutting, or
grinding of various kinds of metals and alloys such as aluminum, aluminum alloy, aluminum
foil.
1. A lubricating oil composition for metal working, comprising: (a) a base oil containing,
as an essential component, straight chain olefin having 6 to 40 carbon atoms; and
(b) at least one compound selected from the group consisting of alcohol, glycol, polyalkylene
glycol, derivative of polyalkylene glycol, and fatty acid.
2. A lubricating oil composition for metal working, comprising: (a) a base oil which
is a mixture of straight chain olefin having 6 to 40 carbon atoms and mineral oil
and/or synthetic oil; (b) at least one compound selected from the group consisting
of alcohol, glycol, polyalkylene glycol, derivative of polyalkylene glycol and fatty
acid.
3. A lubricating oil composition for metal working according to Claim 1 or 2, further
comprising the additional component of (c) at least one compound selected from the
group consisting of phenolic compounds and amine compounds.
4. A lubricating oil composition for metal working, comprising: (a) a base oil containing,
as an essential component, straight chain olefin having 6 to 40 carbon atoms; and
(c) at least one compound selected from the group consisting of phenolic compounds
and amine compounds.
5. A lubricating oil composition for metal working, comprising: (a) a base oil which
is mixture of straight chain olefin having 6 to 40 carbon atoms and mineral oil and/or
synthetic oil; and (c) at least one compound selected from the group consisting of
phenolic compounds and amine compounds.