JP5191219B2 - Grease composition - Google Patents

Description

  The present invention relates to a grease composition that can be applied to lubricating parts such as automotive heat exchangers, air conditioners, and AV equipment, and that is low in evaporation and excellent in low torque.

In recent years, bearings, gears, and the like tend to be used at high temperatures as the speed of rotation is increased by reducing the size and weight of mechanical devices and improving the performance of equipment. In the grease used in such places, the base oil tends to evaporate, and if the base oil evaporates too much, the supply of oil to the lubrication surface decreases and the performance deteriorates. Therefore, the base oil used for such grease is desired to further improve the evaporation characteristics (low evaporation).
On the other hand, under a low temperature such as a cold district in winter, it is desired to start the machine smoothly, that is, to reduce the torque by reducing the viscosity of the base oil in the grease.
In addition, from the viewpoint of environmental issues, factories, transportation companies, etc. are required to reduce power and fuel consumption more than ever, and the grease used in various industrial machines and automobiles also has power and fuel saving effects. Is required. As one of means for obtaining a power saving and fuel saving effect, it is effective to lower the viscosity of the base oil.

By the way, in general, the kinematic viscosity tends to increase when trying to improve the low evaporation property of the base oil, and the kinematic viscosity of the base oil tends to decrease when trying to improve the low torque property with the base oil. That is, there is a demand for a grease that can further improve both the low evaporation property and the low torque property, which are contradictory properties, and can be used for a long time in a wide temperature range from low temperature to high temperature.
Under these circumstances, various trials using synthetic base oils such as carbonate ester oil, polyol ester oil, and diester oil were carried out for the purpose of developing a grease with excellent performance of both low evaporation and low torque. (See Patent Document 1, Patent Document 2, Patent Document 3, and Patent Document 4).

JP-A-1-308496 JP 2001-72988 A JP 2001-3070 A JP 2003-327990 A

  The present invention provides a grease composition that is excellent in low torque at low temperatures and low in evaporation at high temperatures, and can be used for a long time in a wide temperature range from low to high temperatures.

  As a result of intensive studies to achieve the above object, the present inventors have found that a diester oil having a specific structure is low in viscosity while having low viscosity. It has been found that a grease can be obtained that is expected to have low evaporation and low torque and low power consumption at low temperatures. Furthermore, it has been found that the thermal oxidation stability can be improved by mixing a specific amount of ether oil or polyol ester oil as the base oil. The present invention has been completed based on these findings.

That is, according to the present invention, the base oil content is 40 to 97% by mass with respect to the total amount of the grease composition, and the diester oil represented by the general formula (1) is 30 to 95 % by mass with respect to the total amount of the base oil. And a neopentyl-type polyol ester oil comprising an aliphatic carboxylic acid having 4 to 18 carbon atoms having a kinematic viscosity at 40 ° C. of 1 to 40 mm ² / s and a trivalent or tetravalent neopentyl alcohol having 3 to 20 carbon atoms, and A grease composition comprising 5 to 70% by mass of one or more selected from the group consisting of polyphenyl ethers with respect to the total amount of base oil is provided.

R1-OCO- (R2) -COOR3 Formula (1)
(Wherein R1 and R3 are branched aliphatic hydrocarbon groups having 10 carbon atoms, which may be the same or different, and R2 is a divalent aliphatic hydrocarbon group having 8 carbon atoms. .)
Moreover, this invention provides the grease composition whose kinematic viscosity in 40 degreeC of the said neopentyl type polyol ester oil and polyphenyl ether is 7-30 mm < ² > / s in the said grease composition.
The present invention also provides the grease composition, wherein the base oil is a base oil composed of the diester oil and the neopentyl polyol ester oil or polyphenyl ether.

Moreover, this invention contains at least 1 sort (s) chosen from the group which consists of a lithium soap type | system | group thickener and the N-substituted terephthalamic acid metal salt represented by General formula (2) as a thickener in the said grease composition. A grease composition according to claim 1 or 2 is provided.

（式中、Ｒ４は炭素数４〜２２の炭化水素基であり、Ｍは周期律Ｉ族、ＩＩ族、ＩＩＩ族又はＩＶ族の金属であり、ｚはＭの価数と同一の値である。）

Wherein R4 is a hydrocarbon group having 4 to 22 carbon atoms, M is a metal of periodic group I, II, III or IV, and z is the same value as the valence of M. .)

  The grease composition of the present invention has a low viscosity and an excellent low evaporation property at a high temperature, and can be used for a long time in a wide temperature range from a low temperature to a high temperature.

Hereinafter, the grease composition according to the present invention will be described in detail.
<Base oil>
The grease composition of the present invention contains a diester oil represented by the following general formula (1) as a base oil.

R1-OCO- (R2) -COOR3 Formula (1)
(Wherein R1 and R3 are branched aliphatic hydrocarbon groups having 10 carbon atoms, which may be the same or different, and R2 is a divalent aliphatic hydrocarbon group having 8 carbon atoms. .)

R1 and R3 in the general formula (1) is a branched aliphatic hydrocarbon group or different optionally good 10 carbon atoms with the same. Aliphatic hydrocarbon groups are branched, it may be Te either saturated or unsaturated, but saturated ones are preferred branched. Specific examples of the hydrocarbon group include etc. isodecyl group.

R2 in the general formula (1) is a divalent aliphatic hydrocarbon group having 8 carbon atoms . The divalent aliphatic hydrocarbon group may be linear or branched, and may be either saturated or unsaturated, but is preferably a linear alkylene group. Specifically, it is a linear alkylene group having 8 carbon atoms. When the number of carbon atoms in R1 and R3 is too small, the evaporating property is deteriorated, and when it is too large, the viscosity tends to be high. If the number of carbon atoms in R2 is too small, the evaporating property will deteriorate, and if it is too large, the evaporating property tends to deteriorate.
The diester oil of the general formula (1) may be used alone or in combination of two or more.

The content of diester oil of general formula (1) in the base oil is a 95 wt% 30 with respect to the base oil the total amount, preferably at least 50 wt%, more preferably at least 75 wt%. When the content of the diester oil of the general formula (1) in the base oil is less than 30% by mass with respect to the total amount of the base oil, the low evaporation property and the low torque property cannot be sufficiently improved. When considering only the low-evaporation and low-torque performance , the more diester oil of the general formula (1) in the base oil is more preferable . For improving thermal oxidation stability, the later-described polyol ester oil and ether oil are preferred . Containing .
The amount of Po triol ester oil or ether oil is preferably 5 to 70% by weight, based on the total base oil amount, more preferably 5 to 50 mass%, particularly preferably from 5 to 25 wt%. When the blending amount is 5% by mass or more, an effect of improving thermal oxidation stability can be obtained, but when it exceeds 70% by mass, the effect of the diester oil may not be sufficiently obtained, which is not preferable.

  The polyol ester oil is a neopentyl polyol ester composed of an aliphatic carboxylic acid having 4 to 18 carbon atoms and a trivalent or tetravalent neopentyl alcohol having 3 to 20 carbon atoms. Examples of the aliphatic carboxylic acid having 4 to 18 carbon atoms include butyric acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid and the like. Examples of the trivalent or tetravalent neopentyl alcohol having 3 to 20 carbon atoms include trimethylolethane, trimethylolpropane, pentaerythritol and the like, and pentaerythritol is particularly preferable. The carbon number of the aliphatic carboxylic acid and the polyhydric alcohol is preferably not smaller than the above range from the viewpoint of evaporability, and is preferably not larger than the above range from the viewpoint of low viscosity.

Moreover, kinematic viscosity at 40 ° C. The polyol ester oil, for low volatility is preferably ^{1 mm} 2 / s or more, more preferably more than ^{5 mm} 2 / s, particularly preferably at least ^{7 mm} 2 / s . On the other hand, from the viewpoint of low viscosity, it is preferably from 40 mm ² / s, more preferably not more than 35 mm ² / s, and particularly preferably 30 mm ² / s.

Examples of the ether oil include polyphenyl ether, and diphenyl ether represented by the general formula (3) is preferably used.

(In the formula, R4, R5, R6, R7, R8, R9, R10, R11, R12 and R13 are a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms, and at least one of R4 to R13 is (It is a hydrocarbon group having 8 to 22 carbon atoms.)
In General Formula (3), at least one of R4 to R13 is a hydrocarbon group having 8 to 22 carbon atoms, preferably a hydrocarbon group having 8 to 20 carbon atoms, and particularly preferably 12 to 12 carbon atoms. 18 hydrocarbon groups. If the number of carbon atoms is too small, the dispersibility of the thickener tends to deteriorate. On the other hand, if the carbon number is too large, the low temperature fluidity of the base oil tends to deteriorate.

Here, examples of the hydrocarbon group include an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group, and among these, an aliphatic hydrocarbon group is preferable.
Moreover, kinematic viscosity at 40 ° C. The ether oil, for low volatility is preferably ^{1 mm} 2 / s or more, more preferably more than ^{5 mm} 2 / s, and particularly preferably equal to or greater than ^{7 mm} 2 / s. On the other hand, from the viewpoint of low viscosity, it is preferably from 40 mm ² / s, more preferably not more than 35 mm ² / s, and particularly preferably 30 mm ² / s.

The blending amount of the base oil is 40 to 97% by mass, preferably 50 to 95% by mass, particularly preferably 60 to 90% by mass, based on the total amount of the grease composition of the present invention. If the amount of base oil is too small, the lubricity of the product grease will decrease, and if it is too large, it will not become grease and an appropriate consistency will not be obtained.

<Thickener>
Any thickener may be used as the thickener contained in the grease composition of the present invention, for example, lithium soap thickener, composite lithium soap thickener, polyurea and N-substituted terephthalamic acid metal salt. Alternatively, various thickeners such as a mixed system thereof can be used.
Examples of the lithium soap-based thickener include an aliphatic carboxylic acid lithium salt having a hydroxyl group such as lithium-12-hydroxystearate, an aliphatic carboxylic acid lithium salt such as lithium stearate, or a mixture thereof.
Examples of the complex lithium soap thickener include a complex of the above-described aliphatic carboxylic acid lithium salt having a hydroxyl group and a dibasic acid lithium salt. Here, suitable dibasic acids include succinic acid, malonic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid and the like.

（式中、Ｒ４は炭素数４〜２２の炭化水素基であり、Ｍは周期律Ｉ族、ＩＩ族、ＩＩＩ族又はＩＶ族の金属であり、ｚはＭの価数と同一である。） The N-substituted terephthalamic acid metal salt is represented by the following general formula (2).

(In the formula, R 4 is a hydrocarbon group having 4 to 22 carbon atoms, M is a metal of periodic group I, II, III or IV , and z is the same as the valence of M.)

In General formula (2), R4 is a C4-C22 hydrocarbon group, Preferably the carbon number is 14-20. If the number of carbon atoms is too small, the thickener is difficult to disperse in the base oil, and the base oil tends to separate. Moreover, when carbon number is too large, there exists a tendency for shear stability to worsen. Examples of R4 include decyl, tetradecyl, hexadecyl, octadecyl and the like.
M in the general formula (2) are periodic group I, II group is a metal of Group III or Group IV, such as lithium, aluminum, lead and the like. Particularly preferred are sodium, barium, lithium and potassium, with sodium being most preferred.
Z is the same as the valence of M.

一般式（４）中、Ｒ１５、Ｒ１６、Ｒ１７及びＲ１８はそれぞれ炭素数１〜３０の炭化水素基である。Ｒ１５及びＲ１８は、それぞれ脂肪族炭化水素基、脂環式炭化水素基、芳香族炭化水素基又はそれらの組み合わせであり、好ましい炭素数は１〜３０であり、より好ましくは６〜１８である。Ｒ１６及びＲ１７はそれぞれ１〜３０個の炭素原子を有する炭化水素基である。また、ｙは０〜３の整数であり、好ましくは０である。
増ちょう剤には上記に挙げた増ちょう剤を単独でも組み合わせても使用することができるが、特にリチウム石けん系増ちょう剤またはＮ−置換テレフタラミン酸金属塩を用いることにより、さらに低騒音性を向上させることができるため好ましい。 Examples of polyurea include those represented by the following general formula (4).

In the general formula (4), R15, R16, R17 and R18 are each a hydrocarbon group having 1 to 30 carbon atoms. R15 and R18 are each an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, or a combination thereof, and preferably have 1 to 30 carbon atoms, more preferably 6 to 18 carbon atoms. R16 and R17 are each a hydrocarbon group having 1 to 30 carbon atoms. Y is an integer of 0 to 3, preferably 0.
As the thickener, the thickeners listed above can be used alone or in combination. However, the use of a lithium soap thickener or an N-substituted terephthalamic acid metal salt further reduces noise. It is preferable because it can be improved.

  The thickener imparts consistency to the grease composition. If the blending amount is too small, the grease does not become a grease and an appropriate consistency cannot be obtained. It tends to decrease. In order to impart an appropriate consistency and ensure lubricity as a grease, the blending amount of the thickener used in the present invention is 3 to 40% by mass, preferably 5 to 5%, based on the total amount of the grease composition. 20% by mass.

<Other additives>
The grease composition of the present invention can be appropriately mixed with various additives as required.
Examples of additives include metal detergents such as alkaline earth metal sulfonates, alkaline earth metal phenates, alkaline earth metal salicylates; alkenyl succinimides, alkenyl succinimide borated modified products, benzylamine, alkylpolyamines Dispersants such as 2,6-di-tert-butyl-p-cresol, bisphenols such as 4,4′-methylenebis- (2,6-di-t-butylphenol), n-octadecyl- Various antioxidants such as phenolic compounds such as 3- (4′-hydroxy-3 ′, 5′-di-tert-butylphenol) propionate and aromatic amine compounds such as naphthylamines and dialkyldiphenylamines; heavy sulfonic acid Metal salt of carboxylic acid part of polyhydric alcohol Various rust inhibitor such as ether; benzotriazole, various corrosion inhibitor such as benzimidazole and the like.
In addition, the blending amount of these additives, while exhibiting the effect of each additive, prevents the low evaporating property and low torque property of the grease composition, which is the effect of the present application, 0.01-10 mass%, More preferably, it is 0.05-10 mass%, More preferably, it shall be in the range of 0.05-8 mass%.

Next, the present invention will be specifically described with reference to examples. In addition, this invention is not limited at all by these Examples.

(Examples 1 to 4 and Comparative Examples 1 to 6)
In Examples and Comparative Examples, greases containing the following * 1 to * 13 components in the proportions (mass) shown in Tables 1 and 2 were prepared.
When * 3 to * 5 are used among the thickeners, the raw materials of the thickener are reacted in the base oil according to the method described later to make the thickener, and then the proportion of the blending amounts in the table is set. Oil and additive were mixed, and as a result, a grease composition containing each component of * 1 to * 13 was prepared.
The grease composition was prepared by appropriately mixing the components * 1 to * 13 and milling to uniformly disperse the thickener in the grease.

* 1: Each base oil in the table and lithium-12-hydroxystearate (manufactured by Sakai Chemicals; trade name: S7000H) are charged into a lithium-12-hydroxystearate heat-resistant container, heated, and dissolved at about 200 ° C. The base oil was added, cooled, and milled to optimize the crystals of lithium-12-hydroxystearate, and the grease mixed and dispersed in the base oil was prepared.
* 2: Each base oil and lithium stearate (made by Sakai Chemical; trade name: S7000) in the table are put into a lithium-stearate heat-resistant container, heated, dissolved at about 200 ° C., and the base oil added. After cooling, milling was performed to optimize lithium-stearate crystals, and grease mixed and dispersed in the base oil was prepared.

* 3: Add the ether oil and 12-hydroxystearate in the table to a composite lithium soap heat-resistant container and heat. Next, an aqueous lithium hydroxide solution is added at about 80 ° C., and lithium-12-hydroxystearate is generated by a saponification reaction. Further, lithium hydroxide and azelaic acid are added at about 90 ° C. and reacted for about 2 hours to form lithium complex soap. Then, after heating and semi-dissolving, diester oil is added and quenched to optimize the crystals of lithium-12-hydroxystearate / azelaic acid complex soap and mixed and dispersed in the base oil. Adjusted the grease.

* 4: Put ether oil and N-octadecyl terephthalamic acid methyl ester in N-substituted sodium terephthalamate heat-resistant container, heat and dissolve, then cool to 100 ° C or lower and 50 mass% sodium hydroxide Add aqueous solution, heat gradually with good stirring, saponify sufficiently, after completion of saponification, add further base oil at 150 ° C and heat to maximum temperature of 180 ° C, then add diester oil to 60 ° C and cool. Sodium N-octadecyl terephthalate was obtained.

* 5: Each base oil and diphenylmethane-4,4-diisocyanate in the table are put into an aliphatic diurea heat-resistant container, heated, and then octylamine is added at about 60 ° C. and reacted for about 40 minutes. Thereafter, the mixture was heated to 170 ° C. with stirring, the base oil was added, cooled, and then milled to optimize the diurea crystals, and the grease mixed and dispersed in the base oil was prepared.

* 6: Diester oil A
In general formula (1), R1 and R3 are isodecyl groups, R2 is a straight chain and an alkylene group having 8 carbon atoms, 40 ° C. kinematic viscosity: 20.16 mm ² / s.
* 7: Diester oil B
In general formula (1), R1 and R3 are 2-ethylhexyl groups, R2 is a straight chain and an alkylene group having 8 carbon atoms, kinematic viscosity at 40 ° C .: 11.6 mm ² / s.
* 8: Diester oil C
In general formula (1), R1 and R3 are isodecyl groups, R2 is a linear and alkylene group having 4 carbon atoms, 40 ° C. kinematic viscosity: 14.2 mm ² / s

* 9: Diester oil D
In general formula (1), R1 and R3 are isotridecyl groups, R2 is a straight chain and alkylene group having 4 carbon atoms, kinematic viscosity at 40 ° C .: 24 mm ² / s
* 10: Polyol ester oil obtained by adding C8-C10 aliphatic carboxylic acid to polyol ester oil pentaerythritol, 40 ° C. kinematic viscosity: 29.92 mm ² / s
* 11: Ether oil A diphenyl ether oil represented by the general formula (3) having a branched hydrocarbon group having 16 carbon atoms added to one or more of R5 to R14, 40 ° C. kinematic viscosity: 21.5 mm ² / s
* 12: PAO
Polyalphaolefin having a kinematic viscosity at 40 ° C. of 17.32 mm ² / s * 13: Antioxidant octylated phenyl-α-naphthylamine

(Measuring method)
(1) Base oil kinematic viscosity The 40 ° C. and 100 ° C. kinematic viscosity (mm ² / s) of the base oil was evaluated by the kinematic viscosity test method established in JISK 2283.
(2) The evaporative grease composition was applied on a metal plate as a thin film having a length of 20 mm, a width of 50 mm, and a thickness of 2 mm, and the metal plate was allowed to stand in an air bath at 120 ° C. for 168 hours. The amount of evaporation [% by mass] was shown, and the results were also shown in the table.

(3) Low torque
The test was conducted in accordance with the low temperature torque test method of JIS K2200, and as a condition, the starting torque (mN · m) at −40 ° C. was obtained, and the result was also shown in the table.
(4) Acoustic characteristics (low noise)
Low noise characteristics were measured using a general Anderon meter to measure the acoustic characteristics of the bearing. The Anderon meter is a device that extracts a vibration component in the transmission radial direction from the inside to the outside and outputs it as sound from a speaker when the outer ring of the bearing is fixed and the inner ring is rotated at a constant speed. Specifically, a JIS nominal number 608 bearing was used as the Anderon meter bearing, 0.3 g of grease was charged, and the Anderon value of the high band was measured when rotated for 1 minute at a rotation speed of 1800 rpm and a thrust load of 2 kgf. It was done by doing.
The acoustic characteristics (low noise property) are better as the Anderon value is lower.
The evaluation was carried out according to the following criteria with the target of an Anderon value of less than 1.5.
A: Anderon value is less than 1.5.
Δ: Anderon value is 1.5 or more and less than 2.5.
X: Anderon value is 2.5 or more.

(5) Thermal oxidation stability The acid value of the grease before and after the evaporability test was measured and compared.
Acid value increase = acid value after test-acid value before test.
The thermal oxidation stability is better as the acid value increase is smaller.
The evaluation was aimed at an acid value increase of less than 0.3, and when the thermal oxidation stability was particularly required, the target was less than 0.2.

Claims (4)

The base oil content is 40 to 97% by mass with respect to the total amount of the grease composition, and the diester oil represented by the general formula (1) is 30 to 95% by mass with respect to the total amount of the base oil, A group consisting of an aliphatic carboxylic acid having 4 to 18 carbon atoms having a viscosity of 1 to 40 mm ² / s and a neopentyl polyol ester oil composed of a trivalent or tetravalent neopentyl alcohol having 3 to 20 carbon atoms and polyphenyl ether. A grease composition characterized by containing at least one type selected from 5 to 70% by mass based on the total amount of the base oil.

R1-OCO- (R2) -COOR3 Formula (1)
(Wherein R1 and R3 are branched aliphatic hydrocarbon groups having 10 carbon atoms, which may be the same or different, and R2 is a divalent aliphatic hydrocarbon group having 8 carbon atoms. .) The grease composition according to claim 1, wherein the neopentyl polyol ester oil and polyphenyl ether have a kinematic viscosity at 40 ° C. of 7 to 30 mm ² / s. The grease composition according to claim 1 or 2, wherein the base oil is a base oil composed of the diester oil and the neopentyl polyol ester oil or polyphenyl ether. The thickener includes at least one selected from the group consisting of a lithium soap thickener and an N-substituted terephthalamic acid metal salt represented by the general formula (2). The grease composition described in 1.

Wherein R4 is a hydrocarbon group having 4 to 22 carbon atoms, M is a metal of periodic group I, II, III or IV, and z is the same value as the valence of M. .)