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(11) | EP 0 394 468 B1 |
| (12) | EUROPEAN PATENT SPECIFICATION |
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| (54) |
LUBRICATING OIL COMPOSITION SCHMIERÖLZUSAMMENSETZUNG HUILE LUBRIFIANTE |
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| Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). |
TECHNICAL FIELD
[0001] This invention relates to a novel lubricating oil composition, more particularly to a lubricating oil composition for metal working which is suitable as a processing oil for super finishing processing or bearing processing and has excellent stain resistance so that stain will not be generated not only in the absence of sulfur type extreme pressure agents but also in the presence of such agents.
BACKGROUND ART
[0002] Generally in metal working such as cutting or grinding of metal, load applied on frictional surfaces increases, and extrusions between metals break the adsorption oil film and come into contact with each other. As a result, surface temperature rises, and the adsorbed oil film is destroyed and causes seizure or scuffing. Thus, an extreme pressure agent has been conventionally incorporated in a lubricating oil for metal working to decrease friction to ensure that the lubricating oil will not lose lubricating properties under such a condition.
[0003] Cutting or grinding of metal is characterized in that temperature rises greatly and a fresh surface always appears upon cutting or grinding. Therefore, such an extreme pressure agent is required to have sufficient durability against the rise in temperature on friction surfaces and to react rapidly with the friction surfaces so that fresh metal surfaces which will be generated successively can be covered quickly with the lubricating film of the extreme pressure agent. For that reason, a sulfur type or chlorine type agent having high activity is generally used under very high temperature conditions.
[0004] As the sulfur type extreme pressure agent, there are used, for example, sulfur simple substance, a sulfide, a sulfurized fat and oil, a sulfurized mineral oil or the like. However, while a lubricating oil containing the active sulfur is excellent in processability, it has a defect that stains are generated in the processed metal product after processing and causes inevitably the lowering of the product value. Even if a lubricating oil which does not contain the aforementioned active sulfur is used, it is apprehended that stains will be generated by using a working tool (grinder) containing sulfur as an ingredient.
[0005] In EP-A- 97 118, US-A- 416 1451 and US-A- 475 8363 a lubricating oil composition is described containing a base oil, a secondary amine and at least one compound selected from a sulfonate, a phenate and a salicylate. The substituents of said secondary amine can be alkyl, alkylaryl, aralkyl or aryl groups. However, these lubricating oil compositions still do not show a satisfying stain resistance and further possess a strong offensive odour.
[0006] This invention has been made for the purpose of overcoming the defects in conventional lubricating oils for metal working and providing a lubricating oil composition for metal working which is excellent in stain resistance and odour so that stains will not be generated not only in the absence of a sulfur type extreme pressure agent, but also in the presence of such an agent.
[0007] The present inventors have conducted earnest researches for developing a lubricating oil composition for metal working which is excellent in stain resistance. As a result, it has been found that the aforementioned object can be reached by incorporating a specific compound with a base oil. This invention has been accomplished on the basis of this knowledge.
DISCLOSURE OF THE INVENTION
[0008] That is, this invention provides a lubricating oil composition, characterized in that (B) an amine represented by the formula (I) and (C) at least one compound selected from the group consisting of a sulfonate, a phenate and a salicylate are incorporated into (A) a base oil and, if necessary, (D) an extreme pressure agent and/or an oiliness agent are further incorporated into the base oil.
[0010] In the composition of this invention, the base oil used as the component (A) has no limitation except that the viscosity at the temperature of 40°C is in the range of 1 to 300 cSt, and any one of the base oils which have been conventionally used in lubricating oil compositions for metal working such as a mineral oil, a synthetic oil, a sulfurized mineral oil or a sulfurized fat and oil can be used. Particularly, in bearing processing or super finishing processing, the use of a sulfur type base oil such as a sulfurized mineral oil, a sulfurized fat and oil or a sulfurized olefin advantageously gives excellent processability.
[0012] The amine, which is the component (B) in the composition of this invention, is the compound represented by the formula (I).
R¹-NH-R² (I)
wherein R¹ and R² represent respectively a cycloalkyl group having 4 to 30 carbon atoms, preferably 5 to 20 carbon atoms and may be the same or different from each other.
[0013] If R¹ or R² has carbon atoms less than 4, the amine has the problems of odor or solubility. The aforementioned secondary amines include, for example, di(methylcyclohexyl)amine, di(ethylcyclohexyl)amine, di(propylcyclohexyl)amine, dicyclohexylamine, and the like, particularly di(methylcyclohexyl)amine and dicyclohexylamine are preferred.
[0014] As additional compound in the composition of the present invention there can be used a diamine represented by the formula (III) :
wherein n denotes 2 to 6, preferably 3; R³ and R⁴ represent respectively a hydrogen atom or an alkyl group, an alkenyl group, a cycloalkyl group, an alkylaryl group, an aralkyl group or an aryl group having 5 to 30 carbon atoms, preferably 10 to 24 carbon atoms and may be the same or different provided that both of the two do not represent hydrogen atoms simultaneously.
[0015] If n in the above-mentioned formula (III) is less than 2, the amine has a problem of odor; and the amine in which n exceeds 6 is less available. If R³ or R⁴ has carbon atoms less than 5, the amine has the problems of odor or poor solubility; and the amine in which R³ or R⁴ has carbon atoms exceeding 30 is less available.
[0016] The diamines include for example N-laurylpropylenediamine, N-myristylpropylenediamine, N-palmitylpropylenediamine, N-stearylpropylenediamine, N-eicosylpropylenediamine, N-oleylpropylenediamine, N,N-dilaurylpropylenediamine, tallow propylenediamine or the like.
[0017] The amount of these amine or amines to be incorporated is generally selected in the range of 0.1 to 5% by weight, preferably 0.2 to 2% by weight on the basis of the weight of the composition. If the amount is less than 0.1% by weight, the effect of this invention cannot be exhibited satisfactorily. If the amount exceeds 5% by weight, the improvement of the effect corresponding to that amount cannot be expected.
[0018] In the composition of this invention, one or more kinds of the compounds selected from a sulfonate, a phenate and a salicylate are used as the component (C). The base numbers of the sulfonate, phenate and salicylate are not limited specifically and are preferably in the range of 10 to 500 mg KOH/g, more preferably 150 to 500 mg KOH/g, particularly a high base number in the range of 150 to 450 mg KOH/g being preferred. The component having such a high base number has good durability of the effect (particularly stain resistance).
[0019] As the sulfonate, either a petroleum sulfonate or a synthetic sulfonate can be used, and as the salt form, there are mentioned an alkali metal salt, an alkaline earth metal salt, a diamine salt, an ammonium salt or the like. Among these salts, the alkaline earth metal salt, particularly a calcium salt and a barium salt are preferred.
[0020] As the petroleum sulfonate, a sulfonate which is obtained by recovering as a sulfonate a petroleum sulfonic acid which is a by-product during the purification of liquid paraffin with sulfuric acid or by sulfonating a mineral oil having a suitable molecular weight with a sulfonating agent such as concentrated sulfuric acid, fuming sulfuric acid or sulfuric acid anhydride and further converting into a sulfonate is used. Also, as the synthetic sulfonate, there is used a sulfonate obtained by sulfonating bottoms containing as the main component didodecylbenzene as a by-product during the production of dodecylbenzene as a raw material of a synthetic detergent by alkylating, for example, benzene with a propylene tetramer, or by sulfonating dinonylnaphthalene which is obtained by the alkylation of naphthalene with nonene and further converting the sulfonic acid into a salt. The sulfonate having a high base number is obtained by contacting the sulfonate thus obtained with carbon dioxide gas in the presence of an excessive amount of an alkali compound such as an hydroxide, for example calcium hydroxide or barium hydroxide, or an oxide. The sulfonate may be used alone or in combination of the two or more.
[0021] The phenate can be prepared, for example, by reacting an alkylphenol with elementary sulfur and a metal hydroxide in an alcohol as a solvent. As the form of the salt, there are mentioned a variety of salts in the same manner as in the sulfonate, among others a calcium salt being preferred.
[0022] On the other hand, as the salicylate, an alkali metal salt, an alkaline earth metal salt, a diamine salt or an ammonium salt of the alkylsalicylic acid represented by the general formula (II) are used:
wherein R represents an alkyl group. Among these salts, alkaline earth metal salts, especially the calcium salt and the magnesium salt are preferably used. The alkylsalicylic acid can be generally prepared by alkylating phenol with an -olefin having 14 to 18 carbon atoms and subjecting the resultant alkylphenol to Kolbe-Schmidt reaction. The salicylate having a high base number is prepared in the same manner as the aforementioned sulfonate.
[0023] The alkylsalicylic acid in which the alkyl group is placed at the para-position to the hydroxyl group is advantageous because of its excellent dispersibility at high temperatures.
[0024] The salicylate may be used alone or in combination of two or more, and it may also be combined with the aforementioned sulfonate or phenate.
[0025] In the composition of this invention, the sulfonate, the phenate or the salicylate as the component (C) is generally used in an amount of 0.1 to 10% by weight, preferably 0.2 to 5% by weight on the basis of the weight of the composition. If the amount is less than 0.1% by weight, the effect of this invention will not be exhibited satisfactorily; if it exceeds 10% by weight, the improvement of the effect corresponding to that amount cannot be expected. The optimum amount is about 1% by weight to the weight of the composition.
[0026] In the composition of this invention, an extreme pressure agent and/or an oiliness agent can be incorporated as the component (D), if necessary. The extreme pressure agent or the oiliness agent has no particular limitation, and those which is conventionally used in a lubricating oil for the processing of machines can be used. Tile extreme pressure agent reacts in a satisfactory speed with the friction surfaces under the extreme pressure condition of the loading on the friction surfaces, covers quickly the fresh metal surfaces which will generate in succession with the lubricating film, so that the extrusions on the surfaces are protected from fusion or breakage. As the extreme pressure agent, there are mentioned a sulfur type extreme pressure agent such as sulfur as simple substance, a sulfide, a sulfurized olefin, a sulfurized mineral oil, a sulfurized fat and oil or the like; a chlorine type extreme pressure agent such as a chlorinated paraffin, a chlorinated fat and oil, a chlorinated naphthalene, a chlorinated polyphenyl, a chlorinated alkylbenzene, methyl trichlorostearate, pentachloropentadienic acid, dibutyl chlorendate, or the like; a phosphorus type extreme pressure agent such as tributyl phosphate, tricresyl phosphate, trioctyl phosphate, triphenyl phosphate, lauryl acid phosphate, oleyl acid phosphate, a tallow amine salt of octyl phosphate, an oleylamine salt of oleyl acid phosphate, tributylphosphite, dilauryl phosphite or the like; an organic metal compound type extreme pressure agent such as lead naphthenate, lead oleate, a metal salt of an organic dithiophosphate, a metal salt of an organic dithiocarbamate, amine hexafluorotitanate, titanium tetra(dialkyl orthophosphate), a reaction product of tetrabutyl titanate and an polyamine or the like. The extreme pressure agent may be used alone or in combination of two or more.
[0027] On the other hand, the oiliness agent has the effect of adsorbing on metal surfaces and forming a strong adsorption film to decrease friction. As the oiliness agent, there are mentioned, for example, a higher fatty acid such as oleic acid, stearic acid or the like; a higher alcohol such as stearyl alcohol, oleyl alcohol or the like; an amine or an ester. The oiliness agent may be used alone or in combination of two or more, and it may also be combined with the aforementioned extreme pressure agent.
[0028] In the composition of this invention, the extreme pressure agent or the oiliness agent as the component (D) is generally incorporated in an amount of 0.01 to 40% by weight, preferably 0.1 to 20% by weight on the basis of the weight of the composition.
[0029] Moreover, in the lubricating oil composition of this invention, other additives which have been conventionally used in a lubricating oil such as a pour point depressant, a viscosity index improver, an anti-oxidant, an anti-corrosion agent, a detergent dispersant, a rust inhibitor, an antifoamer or the like can be incorporated, if necessary.
[0030] This invention is further described in detail with reference to Examples, which should not be construed to limit the invention.
Stain resistance (1)
[0032] The processed bearings were coated with the composition, stacked and left standing for 3 days under the conditions of 30°C and a humidity of 95%; then the stacked bearings were observed according to the following criteria:
- O:
- no stain
- X:
- stain
Stain resistance (2)
[0033] The composition was boiled together with active sulfur in an amount of 0.5% by weight, and the composition was evaluated in the same manner as the method (1) according to the following criteria:
- O:
- no stain
- X:
- stain
Stain resistance (3)
[0034] The samples in which no stain had been generated on the aforementioned method (1) were left standing under the conditions of a temperature of 40°C and a humidity of 95% for 1 month, and thereafter the samples were evaluated according to the following criteria:
- O:
- no stain
- △:
- small stains in parts
- X:
- large amount of stains
Base oil A:
Base oil B:
Diamine A:
Diamine B:
Secondary amine:
Sulfonate (Ba):
Sulfonate (Ca):
Sulfonate having high base number (Ca):
Sulfonate having high base number (Mg):
Sulfonate(Na);
Sulfonate(diamine);
Sulfonate(ammonium);
Phenate having high base number (Ca)
[0047] Ca salt of phenate having a base number of 200 mg KOH/g Salicylate (Ca):
Ca salt of salicylate which has an alkyl group with 14 to 18 carbon atoms
Salicylate having high base number (Ca):
Extreme pressure agent:
Oiliness agent:
Examples 1 to 5 and Comparative Examples 1 to 20
[0051] Lubricating oil compositions, each having a formulation shown in Table 1 were prepared, and their stain resistances were evaluated. The results are shown in Table 1.
[0052] The extreme pressure agent and the oiliness agent were used as a mixture of the ratio 2 : 1 by weight.
INDUSTRIAL APPLICABILITY
[0053] As described above, the lubricating oil composition of this invention is a lubricating oil composition for metal working which is excellent in stain resistance so that stain will not be generated not only in the absence of a sulfur type extreme pressure agent but also in the presence of such an agent. Thus, the lubricating oil composition of this invention is preferably used particularly for bearing processing or super finishing processing.
(A) a base oil having a kinematic viscosity at 40° C in the range of 1 to 300 cSt and being selected from mineral oil, synthetic oil, sulfurized mineral oil and sulfurized fat and oil are incorporated
(B) an amine represented by the formula (I)
R¹-NH-R² (I )
wherein R¹ and R² represent a cycloalkyl group having 4 to 30 carbon atoms and may
be the same or different from each other and
(C) at least one compound having a base number in the range of 10 to 500 mg KOH/g
which is selected from the group consisting of a sulfonate, selected from the group
consisting of a petroleum sulfonate, a synthetic sulfonate and their salt forms selected
from the group consisting of an alkali metal salt, an alkaline earth metal salt, a
diamine salt and an ammonium salt, a phenate and its salt form selected from the group
consisting of an alkali metal salt, an alkaline earth metal salt, a diamine salt and
an ammonium salt, and a salicylate selected from the group consisting of an alkali
metal salt, an alkaline earth metal salt, a diamine salt and an ammonium salt of the
alkylsalicylic acid represented by the general formula (II ):
wherein R represents an alkyl group.
wherein n denotes 2 to 6; R³ and R⁴ represent respectively a hydrogen atom or an alkyl group, an alkenyl group, a cycloalkyl group, an alkylaryl group, an aralkyl group or an aryl group having 5 to 30 carbon atoms and may be the same or different provided that both of the two do not represent hydrogen atoms simultaneously.
A) einem Grundöl (Basisöl) mit einer kinematischen Viskosität bei 40°C in dem Bereich von 1 bis 300 cSt, das ausgewählt wird aus einem Mineralöl, einem synthetischen Öl, einem sulfurierten Mineralöl und einem sulfurierten Fett und Öl, einverleibt werden
B) ein Amin der Formel (I)
R¹-NH-R² (I)
worin R¹ und R², die gleich oder voneinander verschieden sein können, für eine Cycloalkylgruppe
mit 4 bis 30 Kohlenstoffatomen stehen, und
C) mindestens eine Verbindung mit einer Basenzahl in dem Bereich von 10 bis 500 mg
KOH/g, die ausgewählt wird aus der Gruppe, die besteht aus einem Sulfonat, ausgewählt
aus der Gruppe, bestehend aus einem Petrolsulfonat, einem synthetischen Sulfonat und
ihren Salzformen, ausgewählt aus der Gruppe, bestehend aus einem Alkalimetallsalz,
einem Erdalkalimetallsalz, einem Diaminsalz und einem Ammoniumsalz, einem Phenolat
und seinen Salzformen, ausgewählt aus der Gruppe, bestehend aus einem Alkalimetallsalz,
einem Erdalkalimetallsalz, einem Diaminsalz und einem Ammoniumsalz, und einem Salicylat,
ausgewählt aus der Gruppe, bestehend aus einem Alkalimetallsalz, einem Erdalkalimetallsalz,
einem Diaminsalz und einem Ammoniumsalz der Alkylsalicylsäure der allgemeinen Formel
(II):
worin R für eine Alkylgruppe steht.
D) mindestens ein Additiv, das ausgewählt wird aus Extremdruckmitteln, ausgewählt aus der Gruppe, bestehend aus einem Extremdruckmittel vom Schwefel-Typ, einem Extremdruckmittel vom Chlor-Typ, einem Extremdruckmittel vom Phosphor-Typ und einem Extremdruckmittel vom metallorganischen Verbindungs-Typ, und schmierfähig (ölig) machenden Agentien, ausgewählt aus der Gruppe, bestehend aus einer höheren Fettsäure, einem höheren Alkohol, einem Amin und einem Ester.
worin n für eine Zahl von 2 bis 6 steht; R³ und R⁴, die gleich oder verschieden sein können, jeweils für ein Wasserstoffatom oder eine Alkylgruppe, eine Alkenylgruppe, eine Cycloalkylgruppe, eine Alkylarylgruppe, eine Aralkylgruppe oder eine Arylgruppe mit 5 bis 30 Kohlenstoffatomen stehen, mit der Maßgabe, daß nicht beide gleichzeitig Wasserstoffatome darstellen können.
(A) une huile de base présentant une viscosité cinématique à 40°C dans la gamme de 1 à 300 cSt et étant choisie parmi les huiles minérales, les huiles synthétiques, les huiles minérales sulfurées et les huiles et les graisses sulfurées, sont incorporées :
(B) une amine réprésentée par la formule (I)
R¹-NH-R² (I)
dans laquelle R¹ et R² représentent un groupe cycloalkyle ayant de 4 à 30 atomes de
carbone et peuvent être identiques ou différents l'un de l'autre et
(C) au moins un composé ayant un indice de base dans la gamme de 10 à 500 mg KOH/g
qui est choisi dans le groupe constitué d'un sulfonate, choisi dans le groupe constitué
d'un sulfonate de pétrole, d'un sulfonate synthétique ainsi que de leurs formes salines,
choisies dans le groupe constitué par un sel de métal alcalin, un sel de métal alcalino-terreux,
un sel de diamine et un sel d'ammonium, un phénate et sa forme saline choisies dans
le groupe constitué d'un sel de métal alcalin, d'un sel de métal alcalino-terreux,
d'un sel de diamine et d'un sel d'ammonium, et un salicylate choisi dans le groupe
constitué d'un sel de métal alcalin, d'un sel de métal alcalino-terreux, d'un sel
de diamine et d'un sel d' ammonium de l'acide alkylsalicylique représenté par la formule
générale (II):
dans laquelle R représente un groupe alkyle.
dans laquelle n se trouve dans la gamme de 2 à 6 ; R³ et R⁴ représentent respectivement un atome d'hydrogène ou un groupe alkyle, un groupe alcényle, un groupe cycloalkyle, un groupe alkylaryle, un groupe aralkyle ou un groupe aryle ayant de 5 à 30 atomes de carbone et peuvent être identiques ou différents sous la condition que les deux ne représentent pas simultanément des atomes d'hydrogène.