JPH05339591A - Lubricating oil composition - Google Patents

Abstract

PURPOSE:To obtain the title composition having excellent frictional characteristics, excellent compatibility with a sealing material, good heat stability, capability of long drain and excellent low-temperature fluidity. CONSTITUTION:The title composition comprises a base oil comprising an ester in which the weight ratio of 5-14C carboxylic acids to 15-38C carboxylic acids is (0.1-50):(99.9-50) and at least 0.1-15wt.%, based on the base oil, at least one component selected between a condensate of a metal alkylaromatic sulfonate with an alkanolamine and a 5-14C carboxylic acid and a reaction product of an amine with a dicarboxylic acid (anhydride) containing a 5-30C alkyl or alkenyl group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricating oil composition containing only an ester having excellent biodegradability as a base oil, and more specifically, it has excellent friction characteristics and compatibility with a sealing material, The present invention relates to a lubricating oil composition having good stability, long drainability, and excellent low temperature fluidity. The lubricating oil composition of the present invention can be used as hydraulic oil or common lubricating oil for construction machinery, agricultural machinery, wet clutch oil, automatic transmission oil, gear oil and the like.

[0002]

2. Description of the Related Art With respect to pollution of the global environment due to ozone layer depletion, global warming, acid rain, etc., various measures for environmental protection are being taken, and lubricating oil is regulated from the prevention of environmental pollution. Is being applied. Especially in Europe, from the viewpoint of nature conservation of forests, lakes and rivers, it has become mandatory to use lubricating oil biodegradable by microorganisms for construction machines, chainsaws, agricultural machines, outboard engine, etc. used in these areas. There is. As a measure against this, ester-based lubricating oils that are better in biodegradability than mineral oils that have been used in the past (Satoshi Ohkawa, Proceedings of the Petroleum Product Forum, 198
1989, page 52) has begun to be recommended, and there is an example where rapeseed oil is actually used as a lubricating base oil for construction machinery in Europe.

[0003]

Ester has excellent biodegradability as compared with mineral oil, and its practical application as a common lubricating oil for construction machinery, agricultural machinery and the like is desired. These common lubricating oils are required to transmit or absorb a predetermined power in the wet clutch and the wet brake, and are required to have a predetermined friction coefficient. Rapeseed oil having a polar group in the molecule exhibits a lower friction coefficient than mineral oil-based diesel engine oils that have been conventionally used as these lubricating oils. If such a lubricating oil having a low friction coefficient is used in a power transmission device, problems such as an abnormal increase in clutch surface temperature and a clutch damage may occur due to a reduction in power transmission ratio and a reduction in braking force. It is known that the coefficient of friction of ester has a correlation with the alkyl chain length in the molecule, and the shorter the alkyl chain length of carboxylic acid, the higher the coefficient of friction. From this point of view, it is possible to change the friction coefficient of the ester by adjusting the alkyl composition.

However, regarding the compatibility between the alkyl chain length of the ester and the sealing material, it is known that the shorter the alkyl group is, the more severe the swelling of the sealing material is (G, va).
nder Waal, Journal Synthet
io Lubrication, Volume 280, No. 1,
Page 4 (1985)). For example, an ester of caproic acid and trimethylolpropane remarkably swells the sealing material, and thus it is difficult to use it alone as a lubricating oil. An object of the present invention is to provide a lubricating oil which uses a highly biodegradable ester as a base oil and which can simultaneously satisfy favorable friction characteristics and favorable compatibility with a sealing material.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have made an ester of a carboxylic acid having a specific carbon number as a base oil, and further have a specific additive. It has been found that the compounding of (1) makes it possible to satisfy both excellent friction characteristics and compatibility with the sealing material at the same time.
That is, the present invention is based on an ester having a weight ratio of (a) a carboxylic acid having 5 to 14 carbon atoms and (b) a carboxylic acid having 15 to 38 carbon atoms of 0.1 to 50: 99.9 to 50. In contrast, alkylaromatic sulfonic acid metal salt, condensation reaction product of alkanolamine and carboxylic acid having 5 to 14 carbon atoms, and divalent carboxylic acid having alkyl group or alkenyl group having 5 to 30 carbon atoms Alternatively, the lubricating oil composition is characterized by containing 0.1 to 15% by weight of one or more components selected from a reaction product of an anhydride thereof and an amine.

In the present invention, when two or more kinds of esters are mixed and used as the base oil, the composition of the carboxylic acid as the whole mixture may be within the above range. The base oil that can be used in the present invention is an ester obtained from a monovalent carboxylic acid, a polyvalent carboxylic acid, a monohydric alcohol, a polyhydric alcohol, etc., and particularly a monovalent carboxylic acid and a monovalent or polyvalent carboxylic acid. Ester of alcohol, ester of polyvalent carboxylic acid and monohydric alcohol, complex ester of monovalent carboxylic acid, polyvalent carboxylic acid and polyhydric alcohol, or polyvalent carboxylic acid, monohydric alcohol and polyhydric alcohol , Animal and vegetable oils, or mixtures thereof. Particularly preferred as the base oil of the present invention are polyhydric alcohol esters or complex esters.

A raw material of the ester which can be used in the present invention is a carboxylic acid having 5 to 14 carbon atoms (a).
As components, valeric acid, 3-methylbutanoic acid, 2,2-dihydroxymethylpropanoic acid as monovalent carboxylic acid,
Pivalic acid, caproic acid, 2-ethylbutanoic acid, 2-methylpentanoic acid, 2,2-dimethylbutanoic acid, n-hebutanoic acid, 2-methylhexanoic acid, 3-methylhexanoic acid, 4-methylhexanoic acid, 5- Methyl hexanoic acid, 2
-Ethylpentanoic acid, 2,2-dimethylpentanoic acid, 2
-Methyl-2-ethylbutanoic acid, caprylic acid, 2-ethylhexanoic acid, isooctanoic acid, n-nonanoic acid, 3,
5,5-trimethylhexanoic acid, 2,2,4,4-tetramethylpentanoic acid, 2-methyloctanoic acid, capric acid, isodecanoic acid, neodecanoic acid, isoundecanoic acid, lauric acid, isotridecanoic acid, myristic acid, Two
-(3-Methylbutyl) -7-methyloctanoic acid, 2-
Examples thereof include (1-methylbutyl) -5-methyloctanoic acid and 2-pentylnonanoic acid, and examples of the polyvalent carboxylic acid include glutaric acid, adipic acid, trimethyladipic acid, pimelic acid, azelaic acid, sebacic acid, phthalic acid, and maleic acid. Acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, benzene-1,2,4-tricarboxylic acid, benzene-1,3,5-tricarboxylic acid, benzene-1,2,4,5- Tetracarboxylic acid etc. are mentioned.

As the component (b) which is a carboxylic acid and has 15 to 36 carbon atoms, n-pentadecanoic acid, palmitic acid, 2-hexyldecanoic acid, stearic acid, 2- (1,3,3) are monovalent carboxylic acids. -Trimethylbutyl)-
5,7,7-trimethyloctanoic acid, isostearic acid, 12-hydroxystearic acid, 2-heptylundecanoic acid, behenic acid, valmitoleic acid, oleic acid,
Examples thereof include ricinoleic acid, linoleic acid, linolenic acid, and erucic acid, and pentadecanedioic acid as a polyvalent carboxylic acid,
Examples thereof include dimer acid and trimer acid. Further, as the polycarboxylic acid constituting the complex ester, succinic acid, maleic acid, hydroxybutanedioic acid and the like can be used in addition to the components (a) and (b).

Alcohols used as raw materials include methanol, ethanol, propanol, isopropanol, and n.
-Butanol, isobutanol, tert-butanol, n-pentanol, 2-methylbutanol, n-hexanol, 2-methylpentanol, 2-ethylbutanol, 2,3-dimethylbutanol, n-heptanol, isoheptanol, n-octanol, 2-ethylhexanol, n-nonanol, isononanol, n-
Decanol, Isodecanol, Isoundecanol, n
-Dodecanol, isotridecanol, n-tetradecanol, isotetradecanol, 2-pentylnonanol, n-hexadecanol, 2-hexyldecanol,
Monohydric alcohols such as n-octadecanol, isooctadecanol, 2-heptylundecanol, octadecenol, docosenol, phenol and benzyl alcohol, neopentyl glycol, 2,2-diethyl-
1,3-propanediol, 2-butyl-2-ethyl-
1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1, 3-propanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,8-
Octanediol, 2-methyl-1,2-propanediol, 3-methyl-1,2-butanediol, 2-methyl-1,2-butanediol, 2-methyl-2,3-butanediol, 2-methyl -2,4-butanediol,
2,4-dimethyl-2,4-pentanediol, 2,2
-Dimethyl-1,3-butanediol, 2,2-dimethyl-1,3-pentanediol, 2,5-dimethyl-
2,5-hexanediol, 2,3-dimethyl-2,3
-Butanediol, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1 , 2-pentanediol, 2,3-pentanediol, 1,6-hexanediol, trimethylolethane, trimethylolpropane, glycerin, 3-methyl-1,3,5-pentanetriol, 1,2,3-butane Triol 1,
2,3, -pentanetriol, 2-methyl-1,2,
3-butanetriol, 2,3,4-pentanetriol, 2,3,4-hexanetriol, 5-ethyl-
4,5,6-nonanetriol, 1,2,4-butanetriol, pentaerythritol, glycerin condensate, trimethylolpropane condensate, pentaerythritol condensate, erythritol, arabitol, sorbitol, mannitol, sorbitan, etc. Examples include polyhydric alcohols.

The carboxylic acid having 5 to 14 carbon atoms, which is the component (a), improves the frictional characteristics, and particularly has 6 to 9 carbon atoms.
Carboxylic acids of are preferred. The carboxylic acid having 15 to 36 carbon atoms of the component (b) improves compatibility with the sealing material, but considering further low temperature fluidity, oleic acid or isostearic acid is preferably 40% by weight or more. , And more preferably 60% by weight
It is above, and the saturated linear fatty acid such as palmitic acid and stearic acid is preferably 20% by weight or less.
It is more preferably not more than wt%. Improve friction characteristics (a)
If the amount of carboxylic acid as a component is too large, the compatibility with the sealing material will not be satisfied, and the compatibility with the sealing material will be improved (b).
If the amount of carboxylic acid as a component is too large, the friction characteristics will be unsatisfactory. The weight ratio is within the range satisfying such contradictory requirements. (A) :( b) = 0.1-50: 99.9-50,
Preferably (a) :( b) = 1 to 45:99 to 55. In the case of a carboxylic acid ester of a monohydric alcohol, the monohydric alcohol having a favorable compatibility with the sealing material has 1 carbon atom.
It is 5 to 26, preferably 15 to 18. The monohydric alcohol that can increase the friction coefficient has 1 to 14 carbon atoms.

The polyhydric alcohol used in the present invention is preferably glycerin or a condensate of glycerin among the above-mentioned ones, but neopentyl glycol, trimethylolpropane, and trimethylolpropane are preferred from the viewpoint of thermal oxidation stability and hydrolysis stability. Neopentyl polyols such as pentaerythritol and dipentaerythritol are particularly preferred. The ester used in the present invention includes a dehydration condensation reaction between a carboxylic acid and an alcohol, a dehydrohalogenation reaction between a carboxylic acid halide and an alcohol, a purification of animal and vegetable oils, a mutual ester, and in some cases, an ester and an alcohol or an ester and a carboxylic acid. It can be obtained by a transesterification reaction with a system of acid. The animal and vegetable oil refined oil can be used as it is as a lubricating oil when the composition of the present invention is satisfied.

The hydroxyl value of the ester used in the present invention is not particularly limited, but is preferably 200 mgKOH / g or less in order to improve turbidity at low temperature and compatibility with the sealing material,
More preferably, it is 50 mgKOH / g or less. The acid value of the ester used in the present invention is not particularly limited, but an acid value of 10 mgKOH / g or less is preferable to prevent corrosion, and more preferably 5 mgKOH / g.
It is below.

In the lubricating oil composition of the present invention, when the above specific ester is used as the base oil, excellent friction characteristics and compatibility with the sealing material can be obtained. An acid metal salt, a reaction product of an alkanolamine and a carboxylic acid having 5 to 14 carbon atoms, and an alkyl or alkenyl group having 5 to 30 carbon atoms 2
Sufficient friction characteristics as a lubricating oil composition by blending 0.1 to 15% by weight, preferably 1 to 12% by weight, of one or a mixture of two or more types of reaction products of a carboxylic acid and an amine. And compatibility with sealant is obtained.
If the amount of this additive exceeds 15% by weight, problems such as turbidity at low temperature, remarkable swelling of the sealant, and marked decrease in the strength of the sealant occur, and if it is less than 0.1% by weight, the intended effect is obtained. Absent.

The alkylaromatic sulfonic acid metal salt used in the present invention is a metal salt of petroleum sulfonic acid or synthetic sulfonic acid. Petroleum sulfonic acid is obtained by sulfonating an alkyl aromatic compound of a lubricating oil fraction of mineral oil by a known method, and synthetic sulfonic acid is obtained by sulfonating alkylbenzene, alkylnaphthalene and the like. In this case, alkylbenzene and alkylnaphthalene are preferable as the alkyl aromatic group, and dinonylnaphthalene is particularly preferable. These sulfonic acid metal salts may be neutral salts or basic salts. As the metal salt, barium salt,
Calcium salts and zinc salts are preferable, and barium salts and zinc salts are particularly preferable.

The condensation reaction product of the alkanolamine and the carboxylic acid having 5 to 14 carbon atoms used in the present invention can be obtained, for example, by reacting them at 100 to 200 ° C. for 1 to 40 hours under a nitrogen stream. .. Examples of the alkanolamine used in the present invention include monoethanolamine, diethanolamine, diisopropanolamine and the like. The carboxylic acid reacted with the alkanolamine is a carboxylic acid having 5 to 14 carbon atoms. When the carbon number exceeds 14, it is not preferable because the friction coefficient becomes low when blended with the base oil, and when the carbon number is 4 or less, It is not preferable because it has low solubility in base oil and causes corrosion due to free carboxylic acid generated by hydrolysis. During the reaction, the molar ratio of alkanolamine / carboxylic acid is 1/3.
5 to 1/1 is preferable.

The reaction product of a divalent carboxylic acid having an alkyl group or an alkenyl group having 5 to 30 carbon atoms and an amine used in the present invention is an unsaturated divalent carboxylic acid or its anhydride with an unsaturated hydrocarbon. It is obtained by reacting a reaction product or its hydride with an amine. When the amine is triethylenetetramine, the reaction conditions are, for example, 1
It is 1 to 10 hours at 20 to 230 ° C.

Examples of unsaturated dicarboxylic acid anhydrides include maleic anhydride, itaconic anhydride, citraconic anhydride and the like. The unsaturated hydrocarbon has 2 to 1 carbon atoms.
0 hydrocarbons or their polymers or copolymers,
For example, ethylene, propylene, butylene, isobutylene, pentene, octene, decene, dodecene, octadecene, phenylbutyne, styrene, α-methylstyrene, α-ethylstyrene, 4-methylstyrene, vinylcyclobutane, vinylcyclohexane, vinylnaphthalene, allylbenzene. And so on. Further, a polyene compound such as butadiene, a polymer or copolymer of a polyene compound such as polybutadiene, and a copolymer of a polyene compound and a monoolefin can also be used. The above unsaturated hydrocarbons have an average carbon number of 5 to 30,
-20 is preferable. When the average carbon number exceeds 30, the effect of increasing the coefficient of friction during blending with the base oil becomes small, and when the average carbon number is less than 5, the solubility in the base oil decreases and turbidity occurs, low temperature stability. It is not preferable because the decrease of As the amine, an alkylamine having 5 to 14 carbon atoms, diethylenetriamine, triethylenetetramine,
Examples thereof include alkylene polyamines such as heptaethylene octamine, and polyethylene imines having an average molecular weight of 200 to 4000.

[0018]

EXAMPLES The present invention will be described below with reference to Examples and Comparative Examples. Table 1 shows the composition and properties of the ester used as the base oil used in the examples and comparative examples of the present invention. The equivalent numbers of carboxylic acid and alcohol are the same. In Table 2, stearic acid used as a raw material of the ester in Table 1,
The fatty acid composition of isostearic acid, oleic acid, coconut oil fatty acid, and rapeseed oil was shown. The caprylic acid, capric acid, lauric acid, 2-ethylhexanoic acid, and adipic acid used as the raw materials for the ester in Table 1 all have 14 carbon atoms.
It contains only the following carboxylic acids: Table 3 shows the performance of the samples of the lubricating oil compositions of Examples and Comparative Examples of the present invention. Table 1
As a base oil, the ester shown in (1) or a mixture thereof is used as a base oil, and A, dinonylnaphthalenesulfonic acid barium neutral salt, and B, dinonylnaphthalenesulfonic acid zinc neutral salt are commercially available products. The diethanolamide and the imide of D, propylene tetramer and the maleic anhydride adduct, and triethylene tetramine were synthesized. The performance of the samples was evaluated with respect to the friction coefficient, the volume change rate of the sealing material, the thermal oxidation stability of the lubricating oil, and the pour point. The measurement of the coefficient of friction is correlated with the coefficient of friction of automatic transmissions, steering clutches, parking brakes, etc. It was carried out using a known micro clutch tester (Komatsu Equipment Co., Ltd.).

The preferable performance of the lubricating oil composition of the present invention is when the coefficient of friction is 0.130 or more at 60 ° C and 120 ° C. As the evaluation of the friction coefficient, ◯ was given to those having a temperature of 0.130 or more at both temperatures, x was given to those having a temperature of less than 0.130, and Δ was given to those having a value of 0.130 or more only at either temperature. The volume change rate of the sealing material was measured for nitrile butadiene rubber, and the value after 72 hours at 120 ° C. was evaluated according to the immersion test method in the JIS K6301 vulcanized rubber physical test method. Those with a volume change rate of 20% or less are preferable, those with 20% or less are marked with ◯, and those with more than 20% are marked with x. Thermal oxidation stability was measured using a hot tube tester (Model HT-202; manufactured by Komatsu Equipment Co., Ltd.)
The test was carried out at 0 ° C. for 16 hours at an air flow rate of 1 ml / min. The color of the lacquer adhered to the glass tube was evaluated by a test, and the hue was measured by using a hot tube rating limit sample (Komatsu Equipment Co., Ltd.), and an integer from 0 to 11
It was expressed by a graded evaluation. The larger the value is, the more the coloring is not exhibited and the better the thermal oxidative stability is. The results are shown in Table 4. The pour point was measured by the method described in JIS K-2269. The results are shown in Table 5.

From the results shown in Table 3, it is apparent that the examples according to the present invention are lubricating oil compositions having excellent friction characteristics and compatibility with the sealing material at the same time. Further, from the evaluation results of the hot tube test shown in Table 4, it can be seen that the thermal oxidation stability is excellent as in the comparative example. Further, the results in Table 5 show that the pour point is low as in the comparative example.

FIG. 1 shows a micro-clutch tester used to measure the above-mentioned friction coefficients. In the figure, 1 is a DC motor, 2 is a connecting portion, 3 is a rotary base coupled by bearings, and 4 is a supply unit. It is a trial clutch disc. Reference numeral 5 is a counter plate made of steel, 6 is a rod for taking out the friction torque, and 7 is a torque detection plate to which a strain gauge is attached. 8 are bearings, respectively. Reference numeral 9 is a lever for pressing the mating plate against the clutch disc with a predetermined load. FIG. 2 shows the above-mentioned clutch disc 4 under test, and 10 is a clutch facing which is attached to the clutch disc 4 and is an asbestos-based paper material. Reference numeral 11 is an oil groove, and 12 is a screw hole for fixing the clutch disc to the rotary table.

To measure the friction coefficient in the micro-clutch tester having this structure, the test clutch disc 4 is inserted between the rotary table 3 and the mating plate 5, and the mating plate 5 is rotated by the lever 9 while rotating the rotary table 3. And push it against the test clutch disc 4. The friction torque at this time is taken out by the rod 6, and the torque detection plate 7 made of a strain gauge is used.
Detected at.

[0023]

[Table 1]

[0024]

[Table 3]

[0025]

[Table 4]

[0026]

[Table 5]

[0027]

EFFECTS OF THE INVENTION The lubricating oil composition of the present invention, by adding a specific additive to a specific ester base oil, simultaneously satisfies excellent friction characteristics and excellent compatibility with a sealing material, and further has thermal stability. Because of its good properties, it is also suitable for long-draining lubricating oil. It also has good low-temperature fluidity and can withstand use in winter. The present invention is characterized in that only a biodegradable ester is used as a base oil from the viewpoint of preventing environmental pollution.For example, when the lubricating oil is used in a completely closed system and there is no concern about environmental pollution. Can also be used by blending a component having poor biodegradability such as mineral oil or polyalpha-olefin. Further, the lubricating oil composition of the present invention can function as a hydraulic oil or a common lubricating oil for construction machinery, agricultural machinery, etc., wet clutch oil, automatic transmission oil, gear oil, etc. , Viscosity index improver, pour point depressant, rust inhibitor, antifoaming agent, extreme pressure agent, corrosion inhibitor, demulsifier, antiwear agent, hydrolysis inhibitor, etc. are added within the range to achieve the object of the present invention. can do.

[Brief description of drawings]

FIG. 1 is a structural explanatory view of a micro clutch tester for measuring a friction coefficient of a lubricating oil composition part according to the present invention.

FIG. 2 is a plan view of a clutch disc.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... DC motor, 2 ... Connection part, 3 ... Rotating table, 4 ... Test clutch disk, 5 ... Mating plate, 6 ... Rod, 7 ... Torque detecting plate, 8 ... Bearing, 9 ... Lever, 10 ... Clutch facing, 11 ... Oil groove, 12 ... Screw hole.

[Table 2]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C10N 10:04 30:02 30:06 30:08 40:04 40:08 (72) Inventor Tsuruoka Kuniaki 2-53-1-203 Nishi, Mukonoso Nishi, Amagasaki City, Hyogo Prefecture (72) Inventor Nobuhiko Shizu 9-2-303 Ikekai Town, Nishinomiya City, Hyogo Prefecture (72) Kazuhito Maeda Nishi Mukonoso Nishi, Amagasaki City, Hyogo Prefecture 2-53-2-301 (72) Fujio Takahashi 1-1-13-207 Higashi-Naruo-cho, Nishinomiya-shi, Hyogo

Claims (1)

[Claims] 1. A weight ratio of (a) a carboxylic acid having 5 to 14 carbon atoms to (b) a carboxylic acid having 15 to 38 carbon atoms is 0.1.
1 to 50: 99.9 to 50 ester as a base oil,
On the other hand, a metal salt of an alkyl aromatic sulfonic acid, a condensation reaction product of an alkanolamine and a carboxylic acid having 5 to 14 carbon atoms, and a divalent carboxylic acid having an alkyl group or an alkenyl group having 5 to 30 carbon atoms or a compound thereof. A lubricating oil composition comprising 0.1 to 15% by weight of one or more components selected from a reaction product of an anhydride and an amine.