JP2008231310A - Diurea grease composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grease composition in which variation of viscosity is small even if it is used at a high temperature for a long period of time, oil separation is suppressed, and elongation of durability is attained. <P>SOLUTION: The diurea grease composition contains a thickener in which diurea compound A and diurea compound B having a specific molecular structure respectively are mixed in a base oil comprising at least one kind of a dialkyl diphenyl ether, an ester based synthetic oil and a poly-α-olefin oil such that the ratio of 10-30 mass% of the thicknener, <obtained by mixing diurea compound A: diurea compound B=50-90:50-10 (mol%), is contained> based on the whole amount of the grease. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a diurea grease composition, and more particularly to a grease composition that has improved durability by suppressing changes in consistency and oil separation when used at a high temperature for a long time.

  In recent years, in various industries such as automobiles and steels, mechanical technology has been remarkably advanced, miniaturization, weight reduction, and high performance of various machine parts have progressed, and lubrication points tend to be hot. For this reason, the grease composition excellent in heat resistance and oxidation stability is required.

  However, the mainstream of grease is a metal soap system, and even a lithium soap grease called universal grease has a dropping point of about 200 ° C. and cannot withstand in a high temperature region of 130 ° C. or higher. For this reason, greases containing various metal composite soaps, sodium terephthalamate, benton or urea compounds as thickeners and fluorine greases are often used as high temperature greases. For example, metal composite soap-based grease has a major drawback in curability over time, sodium terephthalate grease has a large oil separation, benton grease has a disadvantage in lubricity, and fluorine grease is expensive.

  As urea grease, diurea grease and tetraurea grease are mainly used, and have various advantages compared with the above-mentioned grease. However, when tetraurea grease is exposed to a high temperature for a long time, a phenomenon that the consistency is hardened is observed, and the grease is hardened or softened due to a difference in shear rate.

  The characteristics of diurea grease vary greatly depending on the combination of isocyanate and an amine bonded to the terminal. For example, a diurea compound in which an amine having an alkyl group having 8 carbon atoms is bonded to both ends of a diphenylmethane group and a diurea compound in which an amine having an alkyl group having 8 carbon atoms is bonded to both ends of a tolylene group or a vitrylene group are used in combination. Grease (see Patent Document 1), tolylene group, diphenylmethane group or dimethylbiphenylene group, 25 to 45 mol% of a linear saturated alkyl group having 6 to 18 carbon atoms, 50 to 70 mol% of a cycloalkyl group, Urea grease containing a diurea compound having an aromatic hydrocarbon group in a proportion of 5 to 25 mol% as a thickener (see Patent Document 2), a diurea compound obtained by reacting two or more different diisocyanates with an amine Urea grease (see Patent Document 3), etc., having a thickener as a thickener is known. However, even with these diurea greases, the consistency changes when used at high temperatures for a long time, and there is room for improvement as use at higher temperatures is expected in the future.

Japanese Patent Laid-Open No. 1-139696 JP-A-6-88085 Japanese Patent No. 2777728

  The present invention has been made in view of such circumstances, and provides a grease composition that has little change in consistency even when used at a high temperature for a long time, suppresses oil separation, and extends durability. For the purpose.

In order to achieve the above object, the present invention provides the following diurea grease composition.
(1) A diurea compound A represented by general formula (1) and a diurea represented by general formula (2) are added to a base oil composed of at least one of dialkyl diphenyl ether, ester-based synthetic oil and poly-α-olefin oil. A thickener comprising a compound B mixed with diurea compound A: diurea compound B = 50 to 90:50 to 10 (mol%) is contained at a ratio of 10 to 30 mass% of the total amount of grease. Diurea grease composition.

(In the formula, R ₂ is a tolylene group or a bi-tolylene group, and R ₁ is an aromatic hydrocarbon group having 6 to 12 carbon atoms, which may be the same or different.)

(In the formula, R ₄ is a diphenylmethane group, and R ₃ is an aromatic hydrocarbon group having 6 to 12 carbon atoms, which may be the same or different.)
(2) The urea compound A and the urea compound B are obtained by simultaneously reacting a diisocyanate containing R ₂ , a diisocyanate containing R ₄ , an amine containing R ₁ and an amine containing amine R ₃ ( 1) The diurea grease composition described above.
(3) An overbased metal detergent having a total base number of 100 to 500 mgKOH / g is 1 to 10 mass% of the total amount of grease, and a sulfur-phosphorus extreme pressure agent not containing metal is 0.1 to 5 of the total amount of grease. The diurea grease composition as described in (1) or (2) above, which is contained in a proportion by mass.
(4) The diurea grease composition as described in (3) above, wherein the overbased metal detergent is at least one selected from alkaline earth metal sulfonates, phenates and salicylates.
(5) The diurea grease composition as described in (3) above, wherein the sulfur-phosphorus extreme pressure agent is thiophosphate or thiophosphite.

  The diurea grease composition of the present invention includes a thickener in which two diurea compounds having different diisocyanate components are mixed at a specific ratio, and thereby has a consistency even when subjected to a high temperature for a long time as compared with other urea greases. Little change and better durability.

  Hereinafter, the present invention will be described in detail.

[Thickener]
In the present invention, a mixture of a diurea compound A represented by the following general formula (I) and a diurea compound B represented by the general formula (2) is used as a thickener.

R ₂ in the formula is a tolylene group or a vitrylene group. R ₁ is an aromatic hydrocarbon group having 6 to 12 carbon atoms, and two R ₁ may be the same or different. Specifically, it can be obtained by reacting tolylene diisocyanate or bitolylene diisocyanate with an aromatic amine such as aniline, benzylamine, toluidine, or chloroaniline. In addition, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and a mixture thereof can be used as tolylene diisocyanate, and 3,3′-vitrylene-4,4′-diisocyanate is used as vitolylene diisocyanate. Etc. can be used.

R ₄ in the formula is a diphenylmethane group. R ₃ is an aromatic hydrocarbon group having 6 to 12 carbon atoms, and two R ₃ may be the same or different. Specifically, it can be obtained by reacting diphenylmethane diisocyanate with an aromatic amine such as aniline, benzylamine, toluidine or chloroaniline. As diphenylmethane diisocyanate, diphenylmethane-4,4′-diisocyanate can be used.

  The mixing ratio of the above-mentioned diurea compound A and diurea compound B is diurea compound A: diurea compound B = 50 to 90:50 to 10 (mol%), preferably 70 to 90:30 to 10 (mol%). . If the diurea compound A is less than 50 mol%, thermal curing increases, and if it exceeds 90% mol%, oil separation increases, which is not preferable.

  Further, the content of the thickener in the grease composition of the present invention is 10 to 30% by mass, preferably 15 to 25% by mass. If it is less than 10% by mass, it is difficult to maintain the grease state, and if it exceeds 30% by mass, it becomes too hard to provide a sufficient lubrication state.

[Base oil]
As the base oil, dialkyl diphenyl ether, ester synthetic oil and poly α-olefin oil are used alone or in admixture of two or more.

  The dialkyldiphenyl ether is represented by the following general formula (A).

R ₅ , R ₆ and R ₇ in the formula are the same or different groups, one of which is a hydrogen atom, and the other two are alkyl groups, preferably having 8 to 20 carbon atoms. Preferably it is a 12-14 alkyl group.

  Examples of ester synthetic oils include diesters such as di-2-ethylhexyl sebacate, dioctyl adipate, diisodecyl adipate, ditridecyl adipate, polyol esters such as trimethylolpropane caprylate, pentaerythritol-2-ethylhexanoate, and trimellit Aromatic ester oils such as acid esters, trioctyl trimellitate, tridecyl trimellitate, tetraoctyl pyromellitate and the like can be mentioned.

  The poly α-olefin oil is represented by the following general formula (B).

R ₈ in the formula is an alkyl group, and two or more different alkyl groups may be mixed in the same molecule, but is preferably an n-octyl group. N is preferably an integer of 3 to 8.

The base oil kinematic viscosity is preferably 15 to ²⁰⁰ mm ² / s at 40 ° C. In consideration of lubrication characteristics, evaporation characteristics, and low-temperature fluidity, it is more preferably 20 to 150 mm ² / s.

  To the diurea grease composition of the present invention, various additives can be added in appropriate amounts in order to enhance various performances. Among them, overbased metal detergents and sulfur-phosphorus extreme pressures shown below are particularly preferable. It is preferable to add an agent.

[Overbased metal detergent]
The overbased metal detergent is a metal detergent having a total base number of 100 mgKOH / g or more, preferably 150 mgKOH / g or more. The upper limit of the total base number is 500 mgKOH / g, preferably 450 mgKOH / g. When the total base number is less than 100 mgKOH / g, the change in consistency is large when used at a high temperature for a long time, while it is difficult to obtain one having a total base number exceeding 500 mgKOH / g. In the present invention, the total base number is defined in 7. 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

  Of these, alkaline earth metal sulfonates, alkaline earth metal phenates, and alkaline metal earth salicylates are preferred.

  The alkaline earth metal sulfonate is an alkaline earth metal salt of a sulfonated product of a lubricating oil or a synthetic alkyl-substituted aromatic compound having a molecular weight of about 400 to 600, and the metal salt includes calcium salt, magnesium salt or barium. Salts are used, preferably calcium salts are used.

  Alkaline earth metal phenate is an alkaline earth metal salt of an alkylphenol sulfide to which an alkyl group having about 8 to 30 carbon atoms is added. As the metal salt, calcium salt, magnesium salt or barium salt is used. Preferably a calcium salt is used.

  Alkaline earth metal salicylates are those obtained by alkylating phenol with an α-olefin having 14 to 18 carbon atoms to form an alkali metal salt, introducing a carboxyl group by the Kolbe-Schmidt reaction, and converting the phenol into an alkaline earth metal salt by metathesis or the like. Yes, calcium salts and magnesium salts are used as the metal salts, and calcium salts are preferred.

  The compounding amount of the overbased metal detergent is preferably 1 to 10% by mass, more preferably 3 to 7% by mass, based on the total amount of grease. If it is less than 1% by mass, the consistency change becomes large when used for a long time at a high temperature, and if it exceeds 10% by mass, oil separation becomes large.

[Sulfur-phosphorus extreme pressure agent]
As the sulfur-phosphorus extreme pressure agent, it means a substance having a phosphorus atom and a sulfur atom. In addition to those having both a phosphorus atom and a sulfur atom in the molecule such as thiophosphates and thiophosphites, for example, Includes a mixture of a phosphorus extreme pressure agent (having a phosphorus atom in the molecule) and a sulfur extreme pressure agent (having a sulfur atom in the molecule).

  As the thiophosphates, for example, thiophosphates having a basic structure of thiophosphates such as triphenylphosphorothionate (TPPT) can be used. As the thiophosphites, organic trithiophosphite represented by (RS) 3P can be used, and examples thereof include tributyltrithiophosphite and tri (2-ethylhexyl) trithiophosphite.

  The compounding amount of the sulfur-phosphorus extreme pressure agent is preferably 0.1 to 5% by mass, more preferably 1 to 3% by mass, based on the total amount of grease. In addition, when using together a phosphorus type | system | group extreme pressure agent and a sulfur type | system | group extreme pressure agent, it is set as the said compounding quantity in total of both. If the amount is less than 0.1% by mass, the change in the consistency becomes large during use at a high temperature for a long time.

[Other additives]
The diurea grease composition of the present invention includes other antioxidants such as amines such as phenyl-1-naphthylamine, phenols such as 2,6-di-tert-dibutylphenol, sulfurs, and zinc dithiophosphate. Rust preventives such as organic sulfonates such as alkali metals and alkaline earth metals, alkyls, alkyls such as alkenyl succinic acid esters, alkenyl succinic acid derivatives, partial esters of polyhydric alcohols such as sorbitan monooleate; fatty acids, Oiliness improvers such as animal and vegetable oils and montanic acid wax; metal deactivators such as benzotriazole may be added. Moreover, extreme pressure agents other than the above, such as organic molybdenum, may be added. The addition amount of these additives is not particularly limited as long as the object of the present invention is not impaired.

There is no limitation on the production method of the diurea grease composition, and grease containing diurea compound A as a thickener and grease containing diurea compound B as a thickener may be mixed at a predetermined ratio, or in the base oil. The diisocyanate containing R ₂ , the diisocyanate containing R ₄ , the amine containing R ₁ and the amine containing amine R ₃ may be reacted simultaneously.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not restrict | limited by these Examples.

(Examples 1-11, Comparative Examples 1-2)
Test greases containing thickener, base oil and additives were prepared as shown in Tables 1-3. In each of the test greases of Examples, TDI, MDI and p-toluidine were added to the base oil, and diurea compound A and diurea compound B were synthesized simultaneously (simultaneous mixing). Moreover, the numerical value of each component described in each column of the base oil and the thickener, the thickener, the base oil and the additive in the table is the amount with respect to the total amount of the grease. Each test grease was subjected to the following (1) high temperature standing test and (2) oil separation degree test in addition to the dropping point measurement.

(1) High temperature standing test A test grease was uniformly applied to a stainless steel dish (SUS304) to a thickness of 3 mm, and left in a constant temperature bath at 180 ° C. for 240 hours with the top surface opened. After standing, the consistency of the test grease was measured, and the difference from the consistency before heating was determined. Although a result is written together in Tables 1-3, the consistency change was set to less than -100 as the pass.
(2) Oil separation test According to the oil separation test of JIS K2220, the test grease was left in a constant temperature bath at 180 ° C. for 100 hours, and the oil separation after standing was measured. Although a result is written together in Tables 1-3, 10 mass% or less was considered as the pass.

  As shown in Tables 1 to 3, the mixture of diurea compound A and diurea compound B was increased compared to each test grease of the comparative example using either one of diurea compound A or diurea compound B as a thickener. It can be seen that each of the test greases in the examples shows a small change in consistency at high temperatures, a small amount of oil separation, and excellent heat resistance.

Claims (5)

A diurea compound A represented by the general formula (1), a diurea compound B represented by the general formula (2), and a base oil composed of at least one of dialkyl diphenyl ether, ester-based synthetic oil and poly α-olefin oil; A diurea grease comprising: a thickener mixed with diurea compound A: diurea compound B = 50 to 90:50 to 10 (mol%) in a proportion of 10 to 30 mass% of the total amount of grease. Composition.

(In the formula, R ₂ is a tolylene group or a bi-tolylene group, and R ₁ is an aromatic hydrocarbon group having 6 to 12 carbon atoms, which may be the same or different.)

(In the formula, R ₄ is a diphenylmethane group, and R ₃ is an aromatic hydrocarbon group having 6 to 12 carbon atoms, which may be the same or different.) The urea compound A and the urea compound B are obtained by simultaneously reacting a diisocyanate containing R ₂ , a diisocyanate containing R ₄ , an amine containing R ₁ and an amine containing amine R ₃ . Diurea grease composition.   An overbased metal detergent having a total base number of 100 to 500 mgKOH / g is 1 to 10% by mass of the total amount of grease, and a sulfur-phosphorus extreme pressure agent containing no metal is 0.1 to 5% by mass of the total amount of grease. The diurea grease composition according to claim 1, wherein the diurea grease composition is contained in a proportion.   4. The diurea grease composition according to claim 3, wherein the overbased metal detergent is at least one selected from alkaline earth metal sulfonates, phenates and salicylates.   The diurea grease composition according to claim 3, wherein the sulfur-phosphorus extreme pressure agent is thiophosphate or thiophosphite.