Thiadiazole additives and lubricating compositions...

Details Thiadiazole additives and lubricating compositions... Thiadiazole additives and lubricating compositions...

2000-10-20

2002-12-03

Gerstl, Robert (Department: 1626)

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

C508S231000, C508S274000

Reexamination Certificate

active

06489484

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to 2,5-dimercapto-1,3,4-thiadiazole reaction products and adducts useful as extreme pressure additives, and more particularly to 2,5-dimercapto-1,3,4-thiadiazole/glycol reaction products and adducts useful as extreme pressure additives.
BACKGROUND OF THE INVENTION
A variety of additives are used in lubricants to substantially improve performance. For example, extreme pressure additives are routinely incorporated into an untreated (i.e., base) lubricating composition (e.g., grease) to significantly improve performance. Extreme pressure additives are believed to produce a film on the surface of a metal which can both increase the load carrying capacity of lubricant, and protects the metal surface under high load conditions from deterioration due to wear, welding, and abrasion.
Lead naphthenates and lead -dialkyldithiocarbamates are frequently used as additives to improve the EP performance of greases. However, lead is a heavy metal which is considered “poisonous” in all forms. As an alternative, metal additives (such as antimony, zinc, and bismuth) have been used as a replacement for lead. However, these heavy metals still provide environmental concerns regarding the use. Accordingly, it has long been a goal in the art to develop non-metal lubricating materials to replace heavy metal additives while providing acceptable extreme pressure performance.
The effectiveness of potential extreme pressure additives is conventionally ascertained by the 4-Ball Weld Test (ASTM D-2596) and the Timken Load Test (ASTM D-2509). An ideal candidate compound should exhibit good results in both tests since each test quantitates different extreme pressure properties.
Known to those skilled in the art 2,5-dimercapto-1,3,4-thiadiazole (DMTD) derivatives are effective as anti-wear additives in lubricants. Examples of DMTD derivatives useful as anti-wear additives include the monosulfide and disulfide dimers of DMTD as disclosed in U.S. Pat. Nos. 4,517,103 and 5,194,621, maleate adducts of DMTD as disclosed in U.S. Pat. Nos. 5,102,568, 5,055,584 and 5,138,065 and mono-alkylated and thioacteal derivatives as disclosed in U.S. Pat. No. 5,849,925.
DMTD derivatives are also known to provide good 4-Ball Weld properties. In fact, the 4-Ball Weld properties of DMTD derivatives often exceed commercial requirements. Unfortunately, these same derivatives generally exhibit poor Timken Load performance since the DMTD derivatives do not generally provide Timken Loads levels greater than 35 pounds. As a result, commercialization of DMTD derivatives as extreme pressure additives has been limited.
In view of the above, there exists a need in the art for DMTD derivative that provide both adequate 4-Ball Weld and Timken Load properties. Accordingly, it is an object of the present invention to provide DMTD derivatives that provide adequate 4-Ball Weld and Timnken Load properties, which will allow for the effective utilization of DMTD derivatives as extreme pressure additives.
SUMMARY OF THE INVENTION
The present invention provides 2,5-dimercapto-1,3,4-thiadiazole/glycol reaction products and adducts useful as extreme pressure additives. In one embodiment, an additive is provided including a reaction product of:
(A) a thiadiazole compound having formula (I):
where Z is a branched or straight chain C
1
to C
20
alkyl radical, a C
1
to C
20
thioalkyl radical, an alpha bound succinate half or full ester, where the ester alkyl is a C
1
to C
5
alkyl radical, an alkali metal, an alkyloxy linkage having formula (II):
or combinations thereof, where R
1
is hydrogen, a C
1
to C
20
branched or straight chain alkyl radical, a phenyl radical, a C
1
to C
20
branched or straight chain alkyl-substituted-phenyl radical, or combinations thereof and R
2
is hydrogen, a C
1
to C
20
branched or straight chain alkyl radical, a phenyl radical, a C
1
to C
20
branched or straight chain alkyl-substituted-phenyl radical, or combinations thereof; and
(B) a poly(ether)glycol having formula (III):
where Q is a hydroxyl radical, a branched or straight chain C
1
to C
20
alkoxy radical, a branched or straight chain C
1
to C
20
alkoxycarboxyl radical, a mono-substituted, di-substituted, or tri-substituted glycerol residue, hydrogen, or combination thereof; where R
3
and R
5
are hydrogen, or a methyl radical; where R
4
is hydrogen, a branched or straight-chain a C
1
to C
20
alkyl radical, a phenyl radical, a C
1
to C
8
branched or straight chain alkyl-substituted-phenyl radical, a C
1
to C
20
branched or straight chain acyl radical, or combinations thereof; and where n is 1 to 300.
In another embodiment, the present invention provides an additive including a thiadiazole-glycol adduct having formula (IV):
where R
1
is hydrogen, a branched or straight chain C
1
to C
20
alkyl radical, a phenyl radical, a branched or straight chain C
1
to C
20
alkyl-substituted-phenyl radical or combination thereof; where R
3
is hydrogen, a methyl radical, or combinations thereof, where R
4
is hydrogen, a C
1
to C
20
branched or straight chain alkyl radical, a phenyl radical, a branched or straight chain C
1
to C
20
alkyl-substituted-phenyl radical, a branched or straight chain C
1
to C
20
acyl radical, or combinations thereof, and where m is from 1 to 50.
Lubricating compositions including the reaction products and adducts of the present invention are also provided. Advantageously, the lubricating compositions of the invention exhibit significantly improved Timken load properties as compared previous DMTD derivatives. These and other advantages of the present invention will be readily apparent from the detailed description set forth below.
DETAILED DESCRIPTION OF THE INVENTION
Present invention provides reaction products and adducts of mono-substituted-2,5-dimercapto-1,3,4-thiadiazole derivatives (hereinafter “thiadiazole compounds”) and poly(ether)glycols useful as extreme pressure additives in lubricants. The thiadiazole-glycol reaction products and adducts have unexpectedly been found to provide good Timken Load properties in addition to good 4-Ball Weld properties. Advantageously, the reaction products and adducts provide an alternative to the heavy metal extreme pressure additives commonly used in lubricants.
In one embodiment the present invention provides an additive including a reaction product of a thiadiazole compound and a poly(ether)glycol. The thiadiazole compound is a mono-substituted 2,5-dimercapto-1,3,4-thiadiazole having formula (I):
in which the substituent “Z” is either: (1) a branched or straight chain C
1
to C
20
alkyl radical, with C
1
to C
8
radical being preferred; (2) a branched or straight chain C
1
to C
20
thioalkyl radical with a C
1
to C
8
radical being preferred; (3) an alpha bound succinate half or full ester, where the ester alkyl is a C
1
to C
5
alkyl radical; (4) an alkyloxy linkage having formula (II)
(5) an alkali metal; or a combination thereof. In this context, “alpha bound” means that the thiadiazole moiety is bound to a carbon atom in an alpha position relative to the carbonyl moiety of the full or partial ester. When Z is an alkyloxy linkage the substituent R
1
is either: (1) hydrogen; (2) a branched or straight chain C
1
to C
20
alkyl radical, with a C
1
to C
8
alkyl radical being preferred; (3) a phenyl radical; (4) a branched or straight chain C
1
to C
20
alkyl-substituted-phenyl radical, with a C
1
to C
8
alkyl substituent being preferred; or a combination thereof. Likewise, the substituents for R
2
are independently chosen from the same group of substituents described for R
1
. In a preferred embodiment, when Z is an alkyloxy linkage R
1
is hydrogen and R
2
is a C
3
to C
8
alkyl radical.
Thiadiazole compounds falling within the above-described parameter are known in the art and are easily synthesized following known techniques. For example, thiadiazole compounds having an alpha bound succinate half or full ester are disclosed in U.S. Pat. No. 5,055,584, which is incorporated herein by reference.
The second com

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