Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic compound containing boron
Reexamination Certificate
2000-04-03
2002-03-05
Johnson, Jerry D. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic compound containing boron
C548S405000
Reexamination Certificate
active
06352962
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a novel lubricant additive and a lubricant, and particularly to a traction drive fluid. More particularly, the present invention relates to a lubricant used for automobile transmissions in a traction drive type, a push-belt type, a gear (manual) type, a automatic transmission and the like, particularly to an additive and a lubricant that concurrently provide excellent scoring resistance, excellent wear resistance, prolonged surface fatigue life or the like with the traction drive liquid for use in automobile continuous variable transmissions, while keeping the balance of these properties at an optimum level.
2. Description of the Related Art
Automobile transmissions such as a gear (manual) type transmission, a automatic transmission, a push-belt type continuous variable transmission and a traction drive continuous variable transmission are known. These mechanically comprise contact portions having high surface pressure such as a traction drive rolling surface, a gear and a ball-and-roller bearing. Accordingly, lubricants having excellent wear resistance and scoring resistance have been used to prevent the contact portions from wearing and scoring (seizing) and to attain a high traction factor as needed. In the lubricant for the automobile transmissions, especially the traction drive fluid used for the automobile continuous variable transmissions, a mixture of a sulfur-based additive and a phosphorus-based additive that has excellent wear resistance and scoring resistance has been conventionally used.
In recent years, the automobile transmissions are designed to be miniaturized, light-weighted, and to have maximized transmission capacity. A main damage on the lubricated portions of the automobile transmissions is caused by surface fatigue such as pitting.
The mixture of the sulfur-based additive and the phosphorus-based additive that has excellent wear resistance and scoring resistance has less effective to the surface fatigue, rather adversely affects thereon. Therefore, there is a need for an additive that provides excellent wear resistance, excellent scoring resistance and prolonged surface fatigue life with the lubricant for the automobile transmissions, especially the traction drive liquid for use in automobile continuous variable transmissions.
Examples of phosphate ester-based and phosphite ester-based lubricant additives include
(1) a compound having the following general formula (II):
wherein R represents an alkyl group having 2 or 3 carbon atoms, R
3
, R
4
and R
5
each independently represent an alkyl group having 1 to 18 carbon atoms, and X
1
, X
2
and X
3
each independently represent O or S as disclosed in the U.S. Pat. No. 2,750,342,
(2) an ester comprising an aromatic amine and a compound having the following general formula (III):
wherein X represents O or S, at least one X is S; n is 0 or 1, at least three ns are 1; R
6
to R
8
independently represent an alkyl group or an aromatic group as disclosed in the U.S. Pat. No. 3,446,738,
(3) a compound having the following general formula (IV)
Ya—S—Yb (IV)
wherein Ya is a group represented by
Z represents a divalent hydrocarbyl group, R
9
and R
10
independently represent a hydrocarbyl group, a hydrocarbyloxy group or a hydrocarbyl mercapto group having 1 to 10 carbon atoms, R
11
represents a hydrogen atom or a hydrocarbyl group, X presents O or S, Yb represents —R
12
H or —R
12
—S—R
13
(wherein R
12
represents a divalent hydrocarbyl group having 1 to 30 carbon atoms and R
13
represents a hydrogen atom or Ya) as disclosed in the U.S. Pat. No. 4,081,387,
(4) a compound having the following general formula (V):
wherein R
14
represents an alkyl group or an alkenyl group, R
15
represents a hydroxyl group, an alkoxyl group, an alkenyloxy group or R
14
O—(CH
2
CH
2
O)
k
—, wherein k. is an integer of 2 to 4 as disclosed in the U.S. Pat. No. 4,579,672,
(5) a compound having the following general formula (VI):
wherein R
16
represents a hydrocarbon group, p is 1 to 3, R
17
represents an alkylene group, q is 1 to 12, X
4
and X
5
independently represent —O—, —NH— or —S—, R
18
and R
19
independently represent an alkylene group, r is 0 or 1 with the proviso that when r is 1, Y
1
is —O—, —NH—, —S—, —S—S— or —CH
2
—; when r is 0, R
18
and R
19
are combined to form a heterocyclic structure as disclosed in the U.S. Pat. No. 4,776,969,
(6) a reaction product of a sulfur composition, a di- or tri-hydrocarbyl phosphite and an amine compound as disclosed in PCT Patent Publication No. WO88/3554, and
(7) a reaction product of (i) &bgr;-hydroxyethylthioether compound, (ii) phosphite hydrogen dihydrocarbyl and/or phosphite trihydrocarbyl and (iii) a compound containing a reactive hydroxyl group and containing no reactive mercapto group or —SCH
2
CH
2
OH as disclosed in PCT Patent Publication No. WO89/12666.
However, these phosphate ester-based and phosphite ester-based lubricant additives not always provide all of the scoring resistance, the wear resistance and the prolonged surface fatigue life with the lubricants to a sufficient extent.
Alternatively, attempts have been made to use additives such as a sulfur-based additive, a phosphorus-based additive and a ZnDTP (Zirn dialkyl dithiophosphate) additive alone or in combination, which are known as extreme pressure additives for the lubricant used in the automobile transmission. Sufficient wear resistance, scoring resistance and surface fatigue life cannot, however, be obtained concurrently.
Further, it is known that a combination of a sulfur/phosphorus-based additive and a molybdenum-based additive can enhance the surface fatigue life. It is, however, difficult to apply the system to the traction drive fluid, since a friction coefficient of the continuous variable transmissions decreases in the combination system.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a novel additive that provides excellent wear resistance, excellent scoring resistance and prolonged surface fatigue life with a lubricant for automobile transmissions, especially with a traction drive fluid for automobile continuous variable transmissions; and to provide the traction drive fluid that has excellent wear resistance, excellent scoring resistance and prolonged surface fatigue life and are especially suitable for automobile traction drive continuous variable transmissions.
Through intense studies for developing such lubricant additive and the lubricant having above-described excellent properties, the present inventors have found that an additive obtained by heating acidic phosphate ester or a phosphite ester having a specific structure and an imide-based dispersant containing boron under the specific conditions attain the object. It is also found that such additive obtained by heating the phosphate compound and the imide-based dispersant containing boron under the specific conditions to have specific properties is mixed with a base oil at a predetermined ratio, whereby the object is attained. The present invention has been completed based on such discoveries.
Specifically, the present invention provides a lubricant additive, especially an additive for traction drive, obtained by heating an acidic phosphate ester and/or a phosphite ester (A) represented by the general formula (I):
(wherein A represents a hydrogen atom or a hydroxyl group, m is 0 or 1, when m is 0, A is a hydroxyl group, and when m is 1, A is a hydrogen atom or a hydroxyl group, R
1
and R
2
each independently represent a hydrogen atom, or a hydrocarbon group having 1 to 18 carbon atoms that may contain one or more oxygen atoms and/or sulfur atoms, R
1
and R
2
may be the same or different, but both R
1
and R
2
are not simultaneously hydrogen atoms) and an imide-based dispersant containing boron (B) at a temperature of 120 to 150° C. for 5 hours or more.
The present invention provides a traction drive fluid comprising a base oil, and 100 to 600 ppm by weight of the additive expressed in terms of the amount
Hata Hitoshi
Machida Hisashi
Seiki Hiromichi
Idemitsu Kosan Co. Ltd.
Johnson Jerry D.
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