JPH06128582A - Lubricant composition - Google Patents

Abstract

PURPOSE:To improve the abrasion resistance or friction characteristics of a mechanical friction part by adding a friction to a lubricant compsn. comprising a base oil and a liq. crystal. CONSTITUTION:A friction modifier is added to a lubricant compsn. comprising a base oil and a liq. crystal. The friction modifier includes an abrasion preventive, an extreme-pressure additive, an oiliness improver, etc. Examples of the abrasion preventive and the extreme-pressure additive are sulfur-contg. additives represented by the formula: (R3O)3P=S (wherein R is alkyl, allyl, or phenyl) (e.g. a trialkyl phosphorothionate, a triphenyl phosphorothionate, or an alkyl diallyl phosphorothionate). Examples of the oiliness improver are an aliph. monocarboxylic acid (e.g. caprylic or lauric acid) and an aliph. dicarboxylic acid (e.g. adipic or pimelic acid).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a lubricating oil composition supplied to a mechanical friction portion.

[0002]

2. Description of the Related Art The use of liquid crystals as lubricating oil compositions has been studied in the past. For example, Eidinthinkldorf proposed using liquid crystals as a lubricating oil composition as a fluid organic for mechanical parts under variable friction by utilizing the transition between the thermotropic liquid crystal phase and isotropic phase of liquid crystals. (Japanese Patent Laid-Open No. 2-503326).

However, since a single liquid crystal has a narrow temperature range showing a liquid crystal phase, the usable temperature range is generally very narrow. For this reason, the liquid crystals are usually rarely used alone, but mixed and used. Even in that case, the usable temperature range is only between about -30 ° C and about + 150 ° C (Japanese Patent Publication No. 2-21436). This greatly limits the application of liquid crystals as lubricating oil compositions.

As described above, even if the technique of using the liquid crystal alone is not advanced, the technique of dissolving the liquid crystal in the base oil to form a lubricating oil composition is not so advanced, and the above Japanese Patent Publication No. 2-21 is used.
No. 436 publication and ACS SYMPOSIUM SERIES 441, Edited by
Even the lubricating oil composition disclosed in Biresaw, 1990 is not enough for the purpose of merely improving friction characteristics.

[0005]

However, it is generally said that when a lubricating oil composition contains a liquid crystal, it is possible to improve the frictional characteristics in the mechanical friction part to a certain degree. There is a problem in that the wear resistance is low although the friction characteristics are improved. An object of the present invention is to provide a lubricating oil composition capable of improving wear resistance in a mechanical friction portion and improving friction characteristics.

[0006]

The lubricating oil composition of the present invention is characterized in that a friction modifier is added to a lubricating oil composition comprising a base oil and a liquid crystal.

Examples of friction modifiers include antiwear agents,
Extreme pressure agents and oiliness agents can be mentioned. First, as an antiwear agent and an extreme pressure agent, as a sulfur-based additive, a general formula (RO) ₃ P = S (wherein R is an alkyl group, an allyl group,
A phenyl group, which may be the same or different)
Specific examples include trialkylphosphorothionate, triphenylphosphorothionate, and alkyldiallylphosphorothionate.

Further, as the sulfurized olefin, for example, the formula
R ₁ -S _x -R ₂ (where x is an integer of 1 to 8, R ₁ and R
₂ represents a sulfurized olefin represented by an alkyl group, an alkenyl group, an aryl group or an aralkyl group having 4 to 12 carbon atoms. Specifically, olefins such as diisobutyl disulfide, dioctyl polysulfide, di-t-nonyl polysulfide, di-t-butyl polysulfide, dibenzyl polysulfide, diphenyl sulfide, diphenyl disulfide, and further olefins such as polyisobutylene and terpenes are added. It is a compound of sulfurized olefins, isobutylene and sulfur that are sulfurized with sulfur and other sulfurizing agents.

[0009]

[Chemical 1]

Examples include those indicated by.

Further, sulfurized oils and fats such as sulfalized spalm oil and sulfalized dipentene, and thiocarbonates such as xanthic disulfide may be mentioned.

Examples of the zinc dithiophosphate-based additive include zinc primary alkyldithiophosphate, zinc secondary alkyldithiophosphate, zinc alkyl-allyldithiophosphate, zinc allyldithiophosphate and the like.

Examples of phosphorus additives include benzyl diphenyl phosphate, allyl diphenyl phosphate, triphenyl phosphate, tricresyl phosphate, ethyl diphenyl phosphate, tributyl phosphate, dibutyl phosphate, cresyl diphenyl phosphate, Dicresyl phenyl phosphate, ethyl phenyl diphenyl phosphate, diethyl phenyl phenyl phosphate, propyl phenyl diphenyl phosphate, dipropyl phenyl phenyl phosphate, triethyl phenyl phosphate, tripropyl phenyl phosphate, butyl phenyl diphenyl phosphate, dibutyl phenyl Phosphate ester such as phenyl phosphate and tributyl phenyl phosphate , Triisopropyl phosphite, phosphorous acid esters such as diisopropyl phosphite, hexamethylphosphoric triamide, n
Other phosphorus compounds such as -butyl-n-dioctylphosphinate, di-n-butylhexylphosphonate, amine dibutylphosphonate, dibutylphosphoroamidate can be used.

The above-mentioned sulfur-based, zinc dithiophosphate-based, and phosphorus-based additives may be used alone or in combination of two or more. The content ratio of these additives in the lubricating oil composition is 0.01% by weight to 10% by weight, preferably 0.1% by weight to 5% by weight.

As the oiliness agent, an aliphatic monocarboxylic acid,
For example, caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid and the like, and as the aliphatic dicarboxylic acid, adipic acid, pimelic acid,
Examples thereof include suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassic acid, tetradecanedioic acid, and other C _{15 to} C ₃₀ aliphatic dicarboxylic acids.

These oiliness agents may be contained alone or in a mixture in the lubricating oil composition in an amount of 0.01% by weight to 6% by weight, preferably 0.1% by weight to 3% by weight. The oily agent is adsorbed on the surface of the mechanical friction portion, and not only can the friction and wear properties be improved, but also the lubricity can be further improved in cooperation with the liquid crystal.

As the liquid crystal, any thermotropic liquid crystal may be used, and nematic liquid crystal, smectic liquid crystal and cholesteric liquid crystal can be used. In particular, azoxy type, phenylcyclohexane type, ester type, cyanobiphenyl type, The discotics type, the Schiff base type and the like can be used alone or in combination.

These liquid crystals may be contained alone or in a mixture in the lubricating oil composition in an amount of 0.01 to 20% by weight, preferably 0.5 to 10% by weight.

As the lubricating base oil, mineral oil, organic acid ester, phosphoric acid ester, silicone oil, olefin oligomer, polyalkylene glycol, alkylbenzene and its derivatives, fluorine oil, alkylphenyl ether oil, alkylbiphenyl oil, polyphenyl ether. Oil or the like can be used.

Mineral oil is a hydrocarbon oil fraction having a lubricating viscosity, for example, raffinate obtained by subjecting a vacuum distillation distillate oil to extraction treatment with a solvent such as phenol, furfural, N-methylpyrrolidone, etc., such as propane, methyl ethyl ketone, etc. Hydrocarbon distillate obtained after solvent dewaxing with the above solvent and, if necessary, further hydrorefining to improve hue and remove unstable substances, or this hydrocarbon distillate And solvent-extracted, solvent-dewaxed and solvent-deasphalted residual oils can be used. Also, catalytic dewaxing treatment may be performed instead of solvent dewaxing treatment. These refined mineral oils may be paraffinic oils, naphthenic oils or the like alone or mixed hydrocarbon oils in terms of composition. Instead of the solvent extraction treatment, mineral oil obtained by a method of removing an unstable component or a component that deteriorates the viscosity index by hydrocracking treatment may be used. Alternatively, a wax isomerized mineral oil obtained by isomerizing a wax component in the presence of a catalyst and then hydrorefining, distilling, and dewaxing can be included therein.

Next, the organic acid ester has 4 carbon atoms.
Some of them are obtained by reacting an aliphatic dibasic acid or aromatic dibasic acid having 14 to 14 with an aliphatic alcohol having 4 to 14 carbon atoms. Examples of such diesters include dioctyl adipate, di- (1-ethylpropyl) adipate, di- (3-methylbutyl) adipate, di-
(1,3-dimethylbutyl) adipate, di- (2-ethylbutyl) adipate, di (2-ethylhexyl)
Adipate, di- (isooctyl) adipate, di-
(Isononyl) adipate, di- (3,5,5 trimethylhexyl) adipate, di- (isodecyl) adipate, di- (undecyl) adipate, di- (tridecyl) adipate, di- (isotetradecyl) adipate, di- (2,2,4-trimethylpentyl) adipate, di- [mixed (2-ethylhexyl, isononyl)]
Adipate, di- (1-ethylpropyl) azelate,
Di- (2-ethylbutyl) azelate, di- (2-ethylhexyl) azelate, di (isooctyl) azelate, di- (isononyl) azelate, di- (3,5,5
5 trimethylhexyl) azelate, di- (isodecyl) azelate, di- (tridecyl) azelate, di-
[Mixed (2-ethylhexyl, isononyl)] azelate, di- [mixed (2-ethylhexyl, decyl)] azelate, di- [mixed (2-ethylhexyl, isodecyl)] azelate, di- [mixed (2-ethylhexyl,
2-propylheptyl)] azelate, di- [mixture (2
-Ethylhexyl, decyl)] azelate, di- (n-
Butyl) sebacate, di- (isobutyl) sebacate,
Di- (1-ethylpropyl) sebacate, di- (3-methylbutyl) sebacate, di- (1,3-dimethylbutyl) sebacate, di- (2-ethylbutyl) sebacate, di- (2-ethylhexyl) sebacate, di -[2
-(2'-Ethylbutoxy) ethyl] sebacate, di-
(2,2,4-trimethylpentyl) sebacate, di-
(Isononyl) sebacate, di- (3,5,5 trimethylhexyl) sebacate, di- (isodecyl) sebacate, di- (isoundecyl) sebacate, di- (tridecyl) sebacate, di- (isotetradecyl) sebacate, di- [Mixed (2-ethylhexyl, isononyl)]
Sebacate, di- (2-ethylhexyl) glutarate, di- (isoundecyl) glutarate and di- (isotetradecyl) glutarate, di-n-butyl phthalate, di-n-hexyl phthalate, di-n-heptyl phthalate, di- Examples thereof include n-octyl phthalate, di-2-ethylhexyl phthalate, diisononyl phthalate, octyldecyl phthalate, diisodecyl phthalate, and ditridecyl phthalate.

Another type of organic acid ester is neopentyl polyol ester. The neopentyl polyol ester is produced by synthesizing a neopentyl polyol having 5 to 9 carbon atoms and an organic acid having 4 to 18 carbon atoms. Examples of such neopentyl polyol ester (hereinafter, neopentyl is abbreviated as NPG, trimethylolpropane as TMP, and pentaerythritol as PE), NPG.di- (heptanoate), NPG.
Di- (2-ethylbutyrate), NPG.di- (cyclohexanoate), NPG.di- (heptanoate),
NPG • di- (isoheptanoate), NPG • di-
(Octanoate), NPG.di- (2-ethylhexanoate), NPG.di- (isooctanoate), N
PG-di- (isononanoate), NPG-di- (isodecanoate), NPG-di- {mixed (hexanoate, heptanoate)}, NPG-di- {mixed (hexanoate, octanoate)}, NPG-di- {mixed (Hexanoate, nonanoate)}, NPG / di-
{Mixed (heptanoate, octanoate)}, NPG
-Di- {mixed (heptanoate, nonanoate)}, N
PG-di- {mixed (heptanoate, isooctanoate)}, NPG-di- {mixed (heptanoate, isononanoate)}, NPG-di- {mixed (isooctanoate, isononanoate)}, NPG -Di- {mixed (butanoate, tridecanoate)}, NPG-Di- {mixed (butanoate, tetradecanoate)}, NPG-
Di- {mixed (butanoate, hexadecanoate)},
NPG / di- {mixed (butanoate, octadecanoate)}, NPG / di- {mixed (hexanoate, isooctanoate, isononanoate)}, NPG / di-
{Mixed (hexanoate, isooctanoate, isodecanoate)}, NPG / di- {Mixed (heptanoate, isooctanoate, isononanoate)}, NP
G-di- {mixed (heptanoate, isooctanoate, isodecanoate)}, NPG-di- {mixed (octanoate, isononanoate, isodecanoate)}, TMP-tri- (pentanoate), TMP-
Tri- (hexanoate), TMP.tri- (heptanoate), TMP.tri- (octanoate), TMP
-Tri- (nonanoate), TMP-tri- (isopentanoate), TMP-tri- (2-ethylbutyrate), TMP-tri- (isopentanoate), TMP
-Tri- (isooctanoate), TMP-tri- (2
-Ethylhexanoate), TMP-tri- (isononanoate), TMP-tri- (isodecanoate), T
MP-tri- [mixture (butyrate, octadecanoate)], TMP-tri- [mixture (hexanoate, hexadecanoate)], TMP-tri- [mixture (heptanoate, tridecanoate)], TMP-tri- [ Mixed (octanoate, decanoate)], TMP-tri-
[Mixed (octanoate, nonanoate)], TMP
Tri- [mixed (butyrate, heptanoate, octadecanoate)], TMP. Tri- [mixed (pentanoate, heptanoate, tridecanoate)], TMP.
Tri- [mixture (hexanoate, heptanoate, octanoate)], TMP / trinonanoate, TMP /
Tri- [mixture (heptanoate, nonanoate)], T
MP tri- [mixture (heptanoate, octanoate, nonanoate)], PE tetra (pentanoate), PE tetra (hexanoate), PE tetra (isopentanoate), PE tetra (2-ethyl butyrate) ), PE, tetra (heptanoate), PE
・ Tetra (isoheptanoate), PE ・ Tetra (isooctanoate), PE ・ Tetra (2-ethylhexanoate), PE ・ Tetra (nonanoate), PE ・ Tetra (isononanoate) and PE and carbon Examples thereof include esters with a mixture of linear or branched carboxylic acids of the formulas 4 to 9.

Neopentyl polyols other than NPG, TMP and PE, such as 2-methyl-2-propylpropane-1,3-diol, 2,2-diethylpropanediol, trimethylolethane and trimethylolhexane, and organic acids. The polyol ester etc. which were individual or mixed were also mentioned.

As the phosphoric acid ester, tricresyl phosphate, cresyl diphenyl phosphate, propyl phenyl diphenyl phosphate, dipropyl phenyl phenyl phosphate, tripropyl phosphate, dibutyl phenyl phenyl phosphate, butyl phenyl diphenyl phosphate, Tributyl phenyl phosphate, tri (2-ethylhexyl) phosphate, trialkyl phenyl phosphate,
Alkyl phenyl phenyl phosphate etc. can be used.

The olefin oligomer has 2 carbon atoms.
To 14, preferably 4 to 12, with or without a branch in the range, obtained by homopolymerization of any one selected from olefin hydrocarbons or copolymerization of two or more, average molecular weight 100 From about 2000 to about 2000, preferably from 200 to about 1000 products are preferred, especially those with unsaturated bonds removed by hydrogenation.
Preferred olefin oligomers are, for example, polybutene, α-olefin oligomer, ethylene / α-olefin oligomer and the like. As the polybutene, for example, isobutene is the main component, butene-1 and butene-2
Those obtained by copolymerizing the above monomer mixture are preferred. Further, as the α-olefin oligomer, an α-olefin mixture having 6 to 12 carbon atoms obtained by thermal decomposition of hydrocarbon or trimerization to hexamerization of lower olefin, for example, hexene-1 is 25 wt% to 50 wt%, Octene-1
30% to 40% by weight and decene-1 25% by weight
It is possible to use a copolymerized mixture of -40% by weight. Further, an oligomer obtained from a single monomer such as decene is also suitable. Further, as the ethylene / α-olefin oligomer, ethylene is 40% by weight to 90%.
It is possible to use a mixture obtained by mixing and polymerizing monomers in an amount of 10% by weight to 10% by weight of α-olefin, for example, propylene, in an amount of 10% by weight.

The olefin oligomer can be produced by using a Friedel-Crafts type catalyst such as aluminum chloride or boron fluoride, a Ziegler catalyst, or an oxide catalyst such as chromium oxide. The olefin oligomer can be hydrogenated by removing the catalyst from the reaction product and then contacting it with a hydrogenation catalyst such as nickel-molybdenum / alumina under heating and pressure.

Alkylbenzenes, mainly of the alkylbenzene type, can also be used. Alkylbenzene is a by-product when a raw material for detergent is produced by alkylating a branched or linear α-olefin and an aromatic hydrocarbon such as benzene or toluene with a catalyst such as hydrogen fluoride, sulfuric acid or aluminum chloride. Is an oil containing mainly dialkylated aromatic hydrocarbons. Alkyl groups are mainly C _{12 and} include linear and branched alkyl groups.

The polyalkylene glycol is a ring-opening polymer or ring-opening copolymer of a linear or branched alkylene oxide having an alkylene group having 2 to 5, preferably 2 to 3 carbon atoms. The alkylene oxide is ethylene oxide, propylene oxide, butylene oxide, or a mixture thereof, preferably propylene oxide, preferably polyethylene glycol or polypropylene glycol, and having a molecular weight range of 100 to 2000, preferably 200. ~
1000's. Both ends of the molecule are alkyl groups, one end is an alkyl group and one end is a hydroxyl group,
Both ends include hydroxyl groups. The alkyl group is in the range C _{1 to} C ₁₈ .

The lubricating oil composition of the present invention contains 0.001% by weight to 10% by weight, preferably 0.1% by weight to 1% by weight of octadecyltrimethoxysilane, polyvinyl alcohol, polyimide, etc. as a liquid crystal aligning agent. %, It is possible to further improve the friction characteristics.

Further, various additives as described below can be contained depending on the use of the lubricating oil composition. Antioxidants include dioctyldiphenylamine, phenyl-
α-naphthylamine, alkyldiphenylamine, N-
Amine-based antioxidants such as nitrosodiphenylamine,
2.6-di-t-butylparacresol, 4.4'-methylenebis (2.6-di-t-butylphenol),
2.6-di-t-butyl-α-dimethylamine paracresol, phenolic antioxidants such as 2.6-di-t-butylphenol, tris (2.4-di-t-butylphenyl) phosphite, tris Phosphorus-based antioxidants such as nonylphenyl phosphite and triphenyl phosphite may be used, and the use ratio thereof is 0.01 to 10% by weight, preferably 0.01 to 1.0, based on the base oil.
It is advisable to use% by weight.

In addition, 0.1% by weight of a metal detergent such as magnesium sulfonate and calcium sulfonate is used.
2.0% by weight, 0.1% by weight of ashless detergent dispersant such as succinimide type to 10.0% by weight, and 0.1% of viscosity index improver such as polymethacrylate having a molecular weight of 50,000 to 100,000. %
~ 20% by weight, 0.001% by weight of antifoaming agent such as silicone
.About.0.1% by weight, and a pour point depressant such as polymethacrylate having a molecular weight of 50,000 to 100,000 can be added at 0.1% to 5% by weight.

[0032]

It is generally said that when a lubricating oil composition contains a liquid crystal, it is possible to improve the frictional characteristics in the mechanical friction part to a certain degree, but on the contrary, there are some which deteriorate the frictional characteristics. There is a problem in that although the friction characteristics are improved, the wear resistance is low. The present invention provides a lubricating oil composition comprising a base oil and a liquid crystal, and by further adding a friction modifier, the abrasion resistance is improved as compared with the case where the liquid crystal or the friction modifier is contained alone as the lubricating oil composition. The inventors have found that it is possible to improve the properties or the friction characteristics. When an oiliness agent is used as the friction modifier, the friction coefficient can be made lower than that when the additive component is liquid crystal alone. Hereinafter, the present invention will be described with reference to examples.

[0033]

Examples 1-2 Poly- having a viscosity of 4 cSt at 100 ° C.
Liquid crystal [trade name: NEM13] on α-olefin (base oil)
3 mixed liquid crystal (CN transition 20 ° C, NI transition 67 ° C) manufactured by Fuji Dye Co., Ltd.] and dibenzyl sulfide (friction modifier)
Were added in the proportions shown in Table 1 below.

The wear width of the obtained lubricating oil composition was measured using an SRV abrasion tester (manufactured by Optimol). The test was carried out using SUJ-2 steel balls and disks at 40 ° C., a load of 100 N, and an amplitude of 2 mm for 30 minutes. The results are shown in Table 1.
Shown at the same time.

[0035]

Comparative Examples 1 to 6 Lubricating oil compositions having the same composition components in the lubricating oil composition of Example 1 and having the component amounts shown in the following Table 1 were prepared, and similarly tested for wear properties.

[0036]

Comparative Example 7 In the lubricating oil composition of Example 1,
A liquid crystal was not added, and benzotriazole was added in place of dibenzyl sulfide at a ratio shown in Table 1 below to prepare a lubricating oil composition, and similarly tested for abrasion resistance. Benzotriazole is hardly dissolved in the base oil.

[0037]

Comparative Example 8 In the lubricating oil composition of Example 1,
A benzotriazole was used in place of dibenzyl sulfide, and liquid crystals were added in the proportions shown in Table 1 below to prepare a lubricating oil composition, and similarly tested for abrasion resistance. Benzotriazole is hardly dissolved in the base oil.

The results of the test for wear resistance are shown in Table 1 at the same time. Further, the unit of the addition amount in Table 1 below is parts by weight.

[0039]

[Table 1]

As can be seen from the table, excellent wear resistance is exhibited as compared with the case where a liquid crystal or a friction modifier is added alone as an additive in the lubricating oil composition.

[0041]

Examples 3 to 6 / Comparative Examples 9 to 12 Poly-α-olefin (base oil) having a viscosity of 4 cSt at 100 ° C. was mixed with a liquid crystal [trade name: RDP20308 mixed liquid crystal (CN transition −34 ° C.,
NI transition 102.8 ° C) manufactured by Rodic Co., Ltd. (hereinafter, referred to as liquid crystal A), liquid crystal [trade name: RDX4069 mixed liquid crystal (CN transition -30 ° C, NI transition 59.9 ° C) manufactured by Roddick Co., Ltd. (hereinafter, Liquid crystal B)] and tricresyl phosphate (friction modifier) were added in the proportions shown in Table 2 below.

The friction coefficient of the obtained lubricating oil composition was measured using an SRV abrasion tester (manufactured by Optimol).
The test was carried out using SUJ-2 steel balls and disks at 40 ° C., a load of 100 N, and an amplitude of 2 mm for 30 minutes. The results are shown in Table 2 at the same time.

[0043]

[Table 2]

As can be seen from the table, the lubricating oil composition of the present invention has a reduced friction by adding the liquid crystal and the friction modifier as compared with the case where the liquid crystal or the friction modifier is added alone. It can be seen that it can be a coefficient and exhibits excellent friction characteristics.

[0045]

Examples 7 to 8 / Comparative Examples 13 to 16 Poly-α-olefin (base oil) having a viscosity of 4 cSt at 100 ° C. was mixed with liquid crystal [trade name: NEM133 mixed liquid crystal (CN transition 20 ° C., N).
I transition 67 ° C.) manufactured by Fuji Dye Co., Ltd. (hereinafter referred to as liquid crystal A), liquid crystal [trade name: RDX4069 mixed liquid crystal (CN transition −30 ° C., NI transition 59.9 ° C.) manufactured by Rodic Co., Ltd. (hereinafter liquid crystal B)] and stearic acid (friction modifier) were added in the proportions shown in Table 3 below.

The friction coefficient of the obtained lubricating oil composition was evaluated using an SRV abrasion tester (manufactured by Optimol).
The test uses a steel ball and a disc made of SUJ-2 at 40 ° C,
The load was 100 N and the amplitude was 2 mm for 30 minutes. The results are shown in Table 3 at the same time.

[0047]

[Table 3]

As can be seen from the table, the lubricating oil composition of the present invention has a reduced friction by adding the liquid crystal and the friction modifier as compared with the case where the liquid crystal or the friction modifier is added respectively. It can be seen that it can be a coefficient and exhibits excellent friction characteristics.

[0049]

The lubricating oil composition of the present invention improves both wear resistance and frictional characteristics in the mechanical friction portion.

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C10M 135: 22 137: 04 129: 40) C10N 30:06

Claims (1)

[Claims] 1. A lubricating oil composition comprising a base oil and a liquid crystal,
A lubricating oil composition comprising a friction modifier.