Tractions fluids having excellent low temperature properties

Details Tractions fluids having excellent low temperature properties Tractions fluids having excellent low temperature properties

2001-12-28

2003-08-05

McAvoy, Ellen M. (Department: 1764)

Solid anti-friction devices, materials therefor, lubricant or se

Lubricants or separants for moving solid surfaces and...

Organic compound containing silicon

C252S078300

Reexamination Certificate

active

06602830

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to traction fluids suitable for operations under widely varying temperature environments, particularly having excellent low temperature properties. The tractions fluids of this invention comprise blends of organic oils and siloxane compositions. The siloxane compositions may include MTQ, MT, MQ, MDT, MDM, or D units in varying molar percents.
BACKGROUND OF THE INVENTION
Traction is broadly defined as the adhesive friction of a body on a surface on which it moves. A traction drive is a device in which torque is transmitted from an input element to an output element through nominal point or line contact typically with a rolling action by virtue of the traction between the contacting elements.
While traction elements are commonly spoken of as being in contact, it is generally accepted that a fluid film is present therebetween. Almost all traction drives require these fluids, known as traction fluids, to remove heat, to prevent wear at the contact surfaces and to lubricate bearings and other moving parts associated with the drive. Thus, instead of metal to metal rolling contact there is a film of fluid introduced into the contact zone and interposed between the metal elements. High pressures and high shear conditions are found in this area of contact between the roller elements and so the nature of this traction fluid determines to a large extent the limits of performance and the capacity of the drive. It is through the traction fluid's resistance to shear that the torque transmitting ability of a given fluid arises. The torque transmitting ability of a fluid, and thus its suitability as a traction fluid, is measured by and is directly related to its traction coefficient.
Most commercial traction fluids are organic oils although they will also contain other additives useful for reducing wear etc. Unfortunately, these organic oils tend to get very viscous at low temperatures. Since traction fluids are most useful when they can perform over a wide temperature range, attempts have been made to blend these organic oils with various materials in an attempt to widen the range of temperatures in which they can
Most commercial traction fluids are organic oils although they will also contain other additives useful for reducing wear etc. Unfortunately, these organic oils tend to get very viscous at low temperatures. Since traction fluids are most useful when they can perform over a wide temperature range, attempts have been made to blend these organic oils with various materials in an attempt to widen the range of temperatures in which they can operate. Unfortunately, while improvements have been made, the previous blends have not provided all the necessary properties at low temperatures.
It is an object of this invention to provide traction fluids suitable for operations under widely varying temperature environments, particularly having excellent low temperature properties.
SUMMARY OF THE INVENTION
The present invention relates to traction fluids comprising (A) 15 to 99 weight percent of at least one organic oil and (B) 1 to 85 weight percent of at least one siloxane composition chosen from units of formulae
(I) (R
3
SiO
1/2
)(RSiO
3/2
)(SiO
4/2
), (MTQ units)
(II) (R
3
SiO
1/2
)(RSiO
3/2
), (MT units)
(III) (R
3
SiO
1/2
)(SiO
4/2
), (MQ units)
(IV) (R
3
SiO
1/2
)(R
2
SiO
2/2
)(RSiO
3/2
), (MDT units)
(V) (R
3
SiO
1/2
)(R
2
SiO
2/2
), and (MD units)
(VI) (R
2
SiO
2/2
)
a
(D units)
in varying mole percents, where a is an integer ranging from 3 to 20 and each R is independently selected from alkyl groups comprising 1 to 18 carbon atoms and aryl groups comprising 6 to 18 carbon atoms.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is a traction fluid comprising
(A) 15 to 99 weight percent of at least one organic oil; and
(B) 1 to 85 weight percent of at least one siloxane composition chosen from (I) 33 to 80 mole percent units of formula (R
3
SiO
1/2
), 0.2 to 66.8 mole percent units of formula (RSiO
3/2
), and 66.8 to 0.2 mole percent units of formula (SiO
4/2
) having a viscosity of from 1.0 to 50,000 mPa.s at 40° C., where each R is independently selected from alkyl groups comprising 1 to 18 carbon atoms and aryl groups comprising 6 to 18 carbon atoms provided from 10 to 70 mole percent of R groups are not methyl;
(II) 33 to 75 mole percent units of formula (R
3
SiO
1/2
) and 67 to 25 mole percent units of formula (RSiO
3/2
) having a viscosity of from 2.0 to 20,000 mPa.s at 40° C., where each R is independently selected from alkyl groups comprising 1 to 18 carbon atoms and aryl groups comprising 6 to 18 carbon atoms provided from 10 to 70 mole percent of R groups are not methyl;
(III) 33 to 80 mole percent units of formula (R
3
SiO
1/2
) and 67 to 20 mole percent units of formula (SiO
4/2
) having a viscosity of from 1.0 to 70,000 mPa.s at 40° C., where each R is independently selected from alkyl groups comprising 1 to 18 carbon atoms and aryl groups comprising 6 to 18 carbon atoms provided from 10 to 70 mole percent of R groups are not methyl;
(IV) 0 to 28 mole percent units of formula (R
3
SiO
1/2
), 37 to 93 mole percent units of formula (R
2
SiO
2/2
), and 6 to 56 mole percent units of formula (RSiO
3/2
) having a viscosity of from 5.0 to 10,000 mPa.s at 40° C., where each R is independently selected from alkyl groups comprising 1 to 18 carbon atoms and aryl groups comprising 6 to 18 carbon atoms provided from 10 to 70 mole percent of R groups are not methyl and provided further that at least one of the R groups which is not methyl is chosen from alkyl groups comprising 7 to 18 carbon atoms and aryl groups comprising 7 to 18 carbon atoms;
(V) 1 to 100 mole percent units of formula (R
3
SiO
1/2
) and 99 to 0 mole percent units of formula (R
2
SiO
2/2
) having a viscosity of from 1.0 to 50,000 mPa.s at 40° C., where each R is independently selected from alkyl groups comprising 1 to 18 carbon atoms and aryl groups comprising 6 to 18 carbon atoms provided from 10 to 70 mole percent of R groups are not methyl and provided further that at least one of the R groups which is not methyl is chosen from alkyl groups comprising 7 to 18 carbon atoms and aryl groups comprising 7 to 18 carbon atoms; and
(VI) cyclosiloxanes of formula (R2SiO
2/2
)
a
having a viscosity of from 2.0 to 50,000 mPa.s at 40° C., where a is an integer ranging from 3 to 20, each R is independently selected from alkyl groups comprising 1 to 18 carbon atoms and aryl groups comprising 6 to 18 carbon atoms provided from 10 to 70 mole percent of R groups are not methyl.
The traction fluids useful in the present method comprise (A) 15 to 99 weight percent of at least one organic oil; and (B) 1 to 85 weight percent of at least one siloxane composition chosen from (I)-(VI) described above.
Component (A) comprises at least one organic oil. The term “organic” as used herein means materials comprising carbon chains or rings and the substituents bonded to those carbon chains or rings may include hydrogen atoms, oxygen, and nitrogen where the oxygen and nitrogen may also be part of the carbon chain. Examples of organic oils included in this definition are hydrocarbons such as alicyclic materials and linear hydrocarbon polymers; oxygen-containing materials such as ethers, esters, ketones, and acids; and nitrogen-containing materials such as amines, amides, and ureas.
The alicyclic materials can include saturated fused rings, saturated rings joined by a divalent group, and saturated rings linked directly to each other but not fused. The materials are commercially available or may be prepared by methods known in the art.
Examples of alicyclic materials include bis-decalin, as described in JP 61-004796; tetramethyldecalin, as described in JP 63-222128 and U.S. Pat. No. 3,803,037; cyclohexyl-substituted indanes, as described in JP 63-063789; fluorene, also described in JP 63-063789; acenaphthene, as described in EP 269,089 and JP 71-33235; hydrogenated naphthalene, as described in EP 240,814; dicyclohexyl alkanes, as described in JP 61-100533 and U.S. Pat. No. 3,966,624); 2,4

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