JP4659002B2 - Grease composition - Google Patents

Description

  The present invention relates to a grease composition, and in particular, to a grease composition that is suitably used particularly for a constant velocity joint.

  The constant velocity joint is a joint used for a drive transmission shaft from a vehicle mission to a tire. The types of constant velocity joints include fixed joints such as barfield joints, zeppa joints, and undercut free joints, and slide joints such as double offset joints, tripod joints, and cross groove joints. Conventionally, greases containing additives such as molybdenum disulfide and lead compounds have been mainly used in these constant velocity joints, based on base grease consisting of lubricant base oil, lithium soap and urea-based thickener. .

The constant velocity joint grease is required to have performances such as flaking resistance, seizure resistance, wear resistance, and low friction. However, with the recent trend toward higher performance and higher grades of automobiles, the performance of conventional grease has been insufficient, especially in terms of extending the life of constant velocity joints, and improving anti-flaking properties. It is strongly desired.
JP-A-10-183162 JP-A-9-324190 JP-A-8-41485 JP-A-10-183152 Japanese Patent Laid-Open No. 9-100488

  An object of the present invention is to provide a grease composition that is particularly excellent in anti-flaking properties.

（Ｂ）ジハイドロカルビルポリサルファイド及び／又は硫化油脂０．１〜２０質量％、（Ｃ）全塩基価が１００〜５００ｍｇＫＯＨ／ｇの過塩基性亜鉛スルフォネート０．０５〜１０質量％、及び（Ｄ）固体潤滑剤、モリブデンジチオカーバメートからなる極圧剤、酸化防止剤、油性剤、さび止め剤、及び粘度指数向上剤からなる群より選択される少なくとも１種、からなるグリース組成物が提供される。 That is, according to the present invention, based on the total amount of the composition in the lubricating base oil, (A) 2 to 30% by mass of a urea-based thickener represented by the following general formula (1) ,
A-CONH-R ¹ -NHCO-B (1)
(In the formula, A and B are —NHR ² , —NR ³ R ⁴ , or —OR ⁵ , and R ^{2 to} R ⁵ are a cyclohexyl group, an octadecyl group, or a toluyl group. R ¹ is represented by the following formula. Divalent hydrocarbon residue.)

(B) 0.1-20% by mass of dihydrocarbyl polysulfide and / or sulfurized fat / oil, (C) 0.05-10% by mass of overbased zinc sulfonate having a total base number of 100-500 mg KOH / g, and (D And a grease composition comprising at least one selected from the group consisting of a solid lubricant, an extreme pressure agent comprising molybdenum dithiocarbamate, an antioxidant, an oily agent, a rust inhibitor, and a viscosity index improver. .

  Since the grease composition of the present invention is excellent in anti-flaking, seizure resistance, low wear, etc., it is useful as a grease for constant speed gears, transmission gears, steel making facilities, etc. , Zepper joints, fixed joints such as undercut free joints; useful for constant velocity joints such as double offset joints, tripod joints, slide-type joints such as cross groove joints, etc., especially for grease for barfield joints Can do.

Hereinafter, the present invention will be described in more detail.
Examples of the lubricating base oil used in the present invention include mineral oil and / or synthetic oil. Kinematic viscosity of 100 ° C. of the lubricating base oil is usually, 2 to 40 mm ² / s, preferably 3 to 20 mm ² / s. The viscosity index of the lubricating base oil is usually 90 or higher, preferably 100 or higher.

  As mineral oil, the lubricating oil fraction obtained by ordinary pressure distillation and vacuum distillation of crude oil obtained by the method commonly used in the oil refining industry's lubricating oil production process is used for solvent removal, solvent extraction, and hydrogenation. Examples include those purified by performing one or more treatments such as decomposition, solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid washing, and clay treatment. Synthetic oils include, for example, polyα-olefins such as polybutene, 1-octene oligomers, 1-decene oligomers or hydrides thereof; ditridecyl glutarate, di-2-ethylhexyl adipate, diisodecyl adipate, ditridecyl adipate, di-3 -Diesters such as ethylhexyl sebacate; Polyol esters such as trimethylolpropane caprylate, trimethylolpropane pelargonate, pentaerythritol-2-ethylhexanoate, pentaerythritol pelargonate; alkyl naphthalene; alkylbenzene; polyoxyalkylene glycol; poly Examples thereof include phenyl ether; dialkyl diphenyl ether; silicone oil; or a mixture thereof.

The component (A) used in the present invention is a urea thickener represented by the above formula (1) .
In the formula, A and B are —NHR ² , —NR ³ R ⁴ , or —OR ⁵ , and R ^{2 to} R ⁵ are a cyclohexyl group, an octadecyl group, or a toluyl group. R ¹ is a divalent hydrocarbon residue represented by the following formula.

In order to produce these diurea compounds, urea-urethane compounds or diurethane compounds, for example, diisocyanate represented by the formula OCN-R ¹ -NCO and formula R ² NH ₂ , R ³ R ⁴ NH or R ⁵ OH It is obtained by reacting the represented compound or a mixture thereof in a base oil at 10 to 200 ° C. In this case, ^{R 1, R 2, R 3} , R 4 and R ⁵ are the same as ^{R 1, R 2, R 3} , R 4 and R ⁵ in the formula (1).

  The content ratio of the component (A) is 2% by mass, preferably 5% by mass, and 30% by mass, preferably 20% by mass, based on the total amount of the grease composition. If the content of the component (A) is less than 2% by mass, the effect as a thickener is small, so that it does not become a sufficient grease. On the other hand, if it exceeds 30% by mass, the grease becomes too hard and has sufficient lubrication performance. I can't demonstrate it.

  The component (B) used in the present invention is dihydrocarbyl polysulfide and / or sulfurized fat.

Dihydrocarbyl polysulfide is a sulfur compound generally referred to as polysulfide or sulfurized olefin, and is specifically a compound represented by the formula (2).
R ^6- (S) x-R ⁷ (2)
In formula (2), R ⁶ and R ⁷ are the same or different groups, and are a linear or branched alkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an alkylaryl group, or Represents an arylalkyl group, and x represents a number of 2 to 6, preferably 2 to 5. Specific examples of R ⁶ and R ⁷ include n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl Linear, branched alkyl groups such as a group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group; phenyl group, Aryl group such as naphthyl group; tolyl group, ethylphenyl group, propylphenyl group, butylphenyl group, pentylphenyl group, hexylphenyl group, heptylphenyl group, octylphenyl group, nonylphenyl group, decylphenyl group, undecylphenyl group , Dodecylphenyl group, xylyl group, ethylmethylphenyl Group, diethylphenyl group, dipropylphenyl group, dibutylphenyl group, methylnaphthyl group, ethylnaphthyl group, propylnaphthyl group, butylnaphthyl group, dimethylnaphthyl group, ethylmethylnaphthyl group, diethylnaphthyl group, dipropylnaphthyl group, dibutyl And alkylaryl groups such as naphthyl group (including all structural isomers); arylalkyl groups such as benzyl group, phenylethyl group and phenylpropyl group (including all structural isomers).

Among them, R ⁶ and R ⁷ in the formula (2) are each independently an alkyl group having 3 to 18 carbon atoms, an aryl group having 6 to 8 carbon atoms, an alkylaryl group, or an alkylaryl group derived from propylene, 1-butene or isobutylene. Arylalkyl groups are preferred. Specifically, an isopropyl group, a branched hexyl group derived from a propylene dimer, a branched nonyl group derived from a propylene trimer, a branched dodecyl group derived from a propylene tetramer, Branched pentadecyl group derived from propylene pentamer, branched octadecyl group derived from propylene hexamer, sec-butyl group, tert-butyl group, branch derived from 1-butene dimer Octyl group, branched octyl group derived from isobutylene dimer, branched dodecyl group derived from 1-butene trimer, branched dodecyl group derived from isobutylene trimer, 1 butene Alkyl groups such as branched hexadecyl group derived from tetramer and branched hexadecyl group derived from isobutylene tetramer (including all branched isomers); Group, tolyl group, ethylphenyl group, xylyl group and other alkylaryl groups (including all branched isomers); benzyl group, phenylethyl group and other arylalkyl groups (however, including all isomers) ) And the like. Furthermore, R ⁶ and R ⁷ in Formula (2) are more preferably a branched alkyl group having 3 to 18 carbon atoms derived from propylene or isobutylene, and preferably 6 carbon atoms derived from propylene or isobutylene. Particularly preferred are ˜15 branched alkyl groups.

  Although the sulfur content of the dihydrocarbyl polysulfide is arbitrary, the sulfur content is usually 10 to 55% by mass, preferably 20 to 50% by mass from the viewpoint of excellent extreme pressure performance.

  Examples of the sulfurized fats and oils that can be used as the component (B) include animal and vegetable oils and fats such as beef tallow, pork fat and fish fat, rapeseed oil and soybean oil; fatty acids extracted from oleic acid, linoleic acid, linolenic acid and animal and vegetable fats and oils Unsaturated fatty acid esters obtained by reacting these unsaturated fatty acids with various alcohols and acid chlorides; or those obtained by sulfurizing a mixture of these by an arbitrary method. The sulfur content of the sulfurized fat or oil is arbitrary, but the sulfur content is usually 2 to 40% by mass, preferably 5 to 35% by mass from the viewpoint of excellent extreme pressure performance.

  The lower limit of the content ratio of the component (B) is 0.1% by mass, preferably 0.5% by mass, and the upper limit is 20% by mass, preferably 10% by mass, based on the total amount of the grease composition. When the content ratio of the component (B) is less than 0.1% by mass, the anti-seizure property of the grease is not sufficient. On the other hand, when it exceeds 20% by mass, the anti-seizure performance corresponding to the amount added cannot be obtained.

  The component (C) used in the present invention is an overbased zinc sulfonate. The lower limit of the total base number of component (C) is 100 mgKOH / g, preferably 150 mgKOH / g, while the upper limit is 500 mgKOH / g, preferably 450 mgKOH / g. When the total base number of the component (C) is less than 100 mgKOH / g, the synergistic effect with the component (B) on anti-flaking is not sufficient, while it is difficult to obtain a product having a total base number exceeding 500 mgKOH / g. is there. In the present invention, the total base number is defined in 7. of JIS K 2501 “Petroleum products and lubricants—neutralization number test method”. It means the total base number measured by the perchloric acid method based on

  As the component (C), an overbased oil-soluble zinc sulfonate is preferable. This overbased oil-soluble zinc sulfonate means a calcium carbonate-containing overbased oil-soluble zinc sulfonate and / or a calcium borate-containing overbased oil-soluble zinc sulfonate.

  The method for producing the calcium carbonate-containing overbased oil-soluble zinc sulfonate is optional. For example, a calcium base (calcium oxide, hydroxide, etc.) is dispersed in a neutral (normal salt) zinc sulfonate, and further carbonic acid is added. It can be produced by a method in which a carbon dioxide gas and a calcium base are reacted to generate a calcium carbonate dispersion in the system by blowing a gas. The manufacturing method of the calcium borate-containing overbased oil-soluble zinc sulfonate is also arbitrary. For example, a calcium base (calcium oxide, hydroxide, etc.) is dispersed in a neutral (normal salt) zinc sulfonate. A method in which boric acid, borate or borate is added to form a calcium borate dispersion in the system, or boric acid, borate or borate is added to the calcium carbonate-containing overbased oil-soluble zinc sulfonate. It can be produced by a method of reacting calcium carbonate dispersed in the system to calcium borate. These reactions are usually carried out in a solvent such as an aliphatic hydrocarbon solvent such as hexane; a hydrocarbon solvent such as xylene; a light lubricating base oil.

  Examples of boric acid used in the method for producing the calcium borate-containing overbased oil-soluble zinc sulfonate include orthoboric acid, metaboric acid, and tetraboric acid. Examples of the borate include alkali metal salts, alkaline earth metal salts, and ammonium salts of boric acid. Specifically, lithium borate such as lithium metaborate, lithium tetraborate, lithium pentaborate, and lithium perborate; sodium metaborate, sodium diborate, sodium tetraborate, sodium pentaborate, hexaborate Sodium borate such as sodium acidate and sodium octaborate; potassium borate such as potassium metaborate, potassium tetraborate, potassium pentaborate, potassium hexaborate and potassium octaborate; calcium metaborate, calcium diborate, Calcium borates such as tricalcium tetraborate, pentacalcium tetraborate, and calcium hexaborate; boric acids such as magnesium metaborate, magnesium diborate, trimagnesium tetraborate, pentamagnesium tetraborate, and magnesium hexaborate Magnesium; or ammonium metaborate, ammonium tetraborate , Ammonium pentaborate, ammonium borate and ammonium eight boric acid preferably. Further, examples of the boric acid ester include esters of boric acid and preferably an alkyl alcohol having 1 to 6 carbon atoms. Specific examples include monomethyl borate, dimethyl borate, trimethyl borate, monoethyl borate, diethyl borate, triethyl borate, monopropyl borate, dipropyl borate, tripropyl borate, monobutyl borate, dibutyl borate Preferable examples include tributyl borate.

  The neutral (normal salt) zinc sulfonate used for the production of the overbased oil-soluble zinc sulfonate is obtained, for example, by sulfonated an alkyl aromatic compound having a weight average molecular weight of 100 to 1500, preferably 200 to 700. Preferred examples include calcium neutral salts or zinc neutral salts of alkyl aromatic sulfonic acids. Examples of the alkyl aromatic sulfonic acid include petroleum sulfonic acid or synthetic sulfonic acid. As the petroleum sulfonic acid, generally used is a product obtained by sulfonating an alkyl aromatic compound of a lubricating oil fraction of mineral oil, or so-called mahoganic acid produced as a by-product when white oil is produced. In addition, as the synthetic sulfonic acid, for example, an alkylbenzene having a linear or branched alkyl group, which is obtained as a by-product from an alkylbenzene production plant that is a raw material of a detergent or is obtained by alkylating a polyolefin with benzene. And a sulfonated alkylnaphthalene such as dinonylnaphthalene and the like. The sulfonating agent for sulfonating these alkyl aromatic compounds is not particularly limited, and usually fuming sulfuric acid or sulfuric anhydride is used.

  (C) As a component, the commercial item normally diluted with the light lubricating base oil etc. can also be used.

  (C) Although the zinc content rate of a component is arbitrary, from the point which shows the synergistic effect excellent with respect to anti-flaking performance in the composition of this invention, the zinc content rate is 0.5-30 mass%, 1-25 mass% is especially preferable.

  The content ratio of the component (C) is 0.05% by mass, preferably 0.1% by mass, and 10% by mass, preferably 5% by mass, based on the total amount of the grease composition. When the content rate of (C) component is less than 0.05 mass%, the synergistic effect with (B) component with respect to anti-flaking performance is not enough. On the other hand, when it exceeds 10 mass%, the effect corresponding to the addition amount with respect to anti-flaking performance is not acquired.

  The component (D) used in the present invention is at least one selected from the group consisting of a solid lubricant, an extreme pressure agent composed of molybdenum dithiocarbamate, an antioxidant, an oily agent, a rust inhibitor, and a viscosity index improver. is there.

Examples of the solid lubricant include graphite, graphite fluoride, boron nitride, polytetrafluoroethylene, molybdenum disulfide, antimony sulfide, and alkali (earth) metal borate.
Examples of the antioxidant include phenolic compounds such as 2,6-di-t-butylphenol and 2,6-di-t-butyl-p-cresol; dialkyldiphenylamine, phenyl-α-naphthylamine, and p-alkylphenyl. Examples include amine compounds such as -α-naphthylamine; sulfur compounds; phenothiazine compounds.
Examples of the oily agent include amines such as laurylamine, myristylamine, palmitylamine, stearylamine and oleylamine; higher alcohols such as lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol and oleyl alcohol; lauric acid, Higher fatty acids such as myristic acid, palmitic acid, stearic acid, oleic acid; fatty acid esters such as methyl laurate, methyl myristate, methyl palmitate, methyl stearate, methyl oleate; laurylamide, myristylamide, palmityl Amides such as amide, stearylamide and oleylamide;
Examples of the rust inhibitor include metal soaps; polyhydric alcohol partial esters such as sorbitan fatty acid esters; amines; phosphoric acid;
Examples of the viscosity index improver include polymethacrylate, polyisobutylene, polystyrene and the like.

  In order to prepare the grease composition of the present invention, for example, the components (A) to (D) can be mixed and stirred in a lubricating base oil and passed through a roll mill or the like. In addition, the ingredients of the thickener of component (A) are added in advance to the lubricating base oil, melted and mixed with stirring to prepare component (A), and then components (B) to (D) are mixed. It can also be produced by stirring and passing through a roll mill or the like.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited to these.
Examples 1-4 and Comparative Examples 1-6
As a lubricating base oil, a solvent-purified paraffinic mineral oil having a kinematic viscosity at 100 ° C. of 15 mm ² / s was used, and diphenylmethane-4,4′-diisocyanate in an amount shown in Table 1 was dissolved by heating in this base oil. . Then, what melt | dissolved the amines and alcohol which are shown in Table 1 in the base oil by heating was added, and the gel-like (A) component was produced | generated. The composition of the component (A) in each of the generated examples is shown in the following structural formula.

  Next, various additives shown in Table 1 were added to the resulting gel-like component (A), stirred, and then passed through a roll mill to prepare each grease composition. In Comparative Example 1, in place of the component (A), lithium 12-hydroxystearate was dissolved in a lubricating base oil, various additives shown in Table 1 were added, stirred, and then passed through a roll mill to obtain a grease composition. A product was prepared.

Each of the obtained grease compositions was subjected to the bench durability test shown below. The results are shown in Table 1.
<Bench durability test>
The number of cycles until the joint reaches the end of its service life using a commercially available # 87 size barfield joint under the condition that the rotational speed, torque, and operating angle are changed to 1 cycle in consideration of the driving pattern of the car. Evaluated.

  As is apparent from the results of the bench durability test in Table 1, the grease composition of the present invention comprises the grease composition of Comparative Example 1 using a compound other than the component (A) as a thickener, and the component (B). It can be seen that the life of the constant velocity joint can be significantly extended as compared with the grease composition of Comparative Example 2 that does not contain, and the grease composition of Comparative Example 5 that uses neutral zinc sulfonate in place of the component (C). Further, in the case of the grease composition of Comparative Example 6 containing no component (B) or component (C), seizure occurred at the start of the bench durability test, and the test could not be continued.

Claims (2)

Based on the total amount of the lubricant base oil,
(A) 2 to 30% by mass of a urea-based thickener represented by the following general formula (1) ,
A-CONH-R ¹ -NHCO-B (1)
(In the formula, A and B are —NHR ² , —NR ³ R ⁴ , or —OR ⁵ , and R ^{2 to} R ⁵ are a cyclohexyl group, an octadecyl group, or a toluyl group. R ¹ is represented by the following formula. Divalent hydrocarbon residue.)

(B) 0.1-20% by mass of dihydrocarbyl polysulfide and / or sulfurized fat / oil,
(C) 0.05 to 10% by mass of overbased zinc sulfonate having a total base number of 100 to 500 mgKOH / g, and (D) an extreme pressure agent comprising a solid lubricant and molybdenum dithiocarbamate, an antioxidant, an oily agent, A grease composition comprising at least one selected from the group consisting of a rust inhibitor and a viscosity index improver.   The grease composition according to claim 1, wherein the component (D) comprises molybdenum disulfide as a solid lubricant, molybdenum dithiocarbamate as an extreme pressure agent, an amine-based antioxidant as an antioxidant, and an oily agent.