Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic compound containing silicon
Patent
1997-01-24
1998-05-05
Howard, Jacqueline V.
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic compound containing silicon
508206, 508559, 508562, C10M13300, C10M13900, C10M14110
Patent
active
057474303
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This application is a 371 of PCT/US95/09564, filed Jul. 8, 1995.
1. Field of the Invention
The present invention relates to a lubricant composition to be used as a bearing oil such as a lubricant for paper machine, hydraulic oil for injection molding press, and a lubricant for film orientation machine. More specifically, the present invention relates to a lubricant composition with excellent anti-foaming property in particular.
2. Description of the Related Art
Generally, additives to be blended in lubricants are mostly polar compounds, which are surface active. Therefore, when they are added to lubricant base oils, foaming readily occurs.
Furthermore, when lubricants are oxidized and deteriorated during use, or as additives decompose, highly polar oxides may be formed. The increase in polarity makes the lubricants more surface active, increasing the tendency of foaming.
When lubricants are foaming, the following drawbacks may occur problematically;
(1) hydraulic operation is deteriorated because of the increase in compaction of lubricants;
(2) the efficiency of hydraulic pumps decreases;
(3) oil supply into a frictional part is insufficient, causing wear, seizing, and the like;
(4) oxidation is facilitated because of the increase in the contact area between lubricants and air, and the like.
Thus, generally, dimethylsilicones (dimethylsiloxanes) have been most commonly used as an anti-foaming agent for lubricants. One or more dimethylsilicones with a viscosity of 100 mm.sup.2 /s to 100,000 mm.sup.2 /s at 40.degree. C. may be used depending on the base composition of lubricants and the temperature at which lubricants are used.
Generally, anti-foaming property of a lubricant is assessed by a testing method defined by JIS K2518, wherein foaming degree and stability are determined while changing oil temperatures (they are measured at a low temperature of 24.degree. C.). Maximum oil temperature is 95.5.degree. C. Foaming degree and foaming stability are preferably 50 ml or less and 0 ml, respectively. From the respect of the standard, satisfactory results can be brought about by adding about 100 ppm of an anti-foaming agent, e.g., dimethylsiloxane, to a lubricant.
During actual use, the oil temperature is likely to be higher because of the compaction and high power modification of systems. Therefore, the frequency of the elevation of the temperature over 100.degree. C. or more has increased.
Hence, oxidation stability and anti-foaming property against high temperatures are now quite important properties.
The method for assessing the anti-foaming property of lubricants at an oil temperature about 100.degree. C. is illustrated by the ILSAC (International Lubricant Standard Committee) method for assessing the anti-foaming property of an oil at an oil temperature of 150.degree. C.
Lubricants with a higher viscosity produce foam of a larger film thickness, resulting in poor anti-foaming property.
According to the ILSAC test method at 150.degree. C., even after 1 to 100 ppm of dimethylsilicone is added to a lubricant with a viscosity of 68 mm.sup.2 /s or more at 40.degree. C., the lubricant has a foaming degree and foaming stability, both of 100 ml or more, so dimethylsilicone cannot improve the anti-foaming property thereof. If dimethylsilicone is added at 100 ppm or more, dimethylsilicone is uniformly dispersed into oil in a limited manner, so dimethylsilicone is precipitated with no improvement of the anti-foaming property.
The objective of the present invention is to provide a lubricant composition with excellent anti-foaming property under the conditions of higher temperatures.
SUMMARY OF THE INVENTION
The present invention is characterized in that 1 ppm to 500 ppm of organopolysiloxane with a viscosity of 1,000 mm.sup.2 /s to 100,000 mm.sup.2 /s at 40.degree. C. and 1 ppm to 5,000 ppm of ethylene glycol/propylene glycol polymer or a derivative thereof are blended with a base oil with a viscosity of 10 mm.sup.2 /s to 700 mm.sup.2 /s at 40.degree. C.
The base oil includes mineral o
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Matsushita Shozo
Suzuki Naomi
Allocca Joseph J.
Exxon Research and Engineering Company
Howard Jacqueline V.
Toomer Cephia D.
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