Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Heavy metal or aluminum in an organic phosphorus compound...
Reexamination Certificate
2001-02-02
2001-10-09
Howard, Jacqueline V. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Heavy metal or aluminum in an organic phosphorus compound...
C508S491000, C508S545000, C508S584000
Reexamination Certificate
active
06300292
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to a hydraulic oil composition used in hydraulic devices etc. in the fields of architecture etc. and in particular to a hydraulic oil composition excellent in oxidative stability and lubricating properties and superior in biodegradability.
2. Description of the Prior Art
The hydraulic oil used in hydraulic devices such as constructing machines may be leaked into soil or rivers so that biodegradable hydraulic oil is often used for the environment. As the base oil in the biodegradable hydraulic oil, synthetic esters and vegetable oil are generally used, but the synthetic esters have the problem of higher prices and the synthetic esters excellent in biodegradability have the disadvantage of being inferior in oxidative stability. On the other hand, the vegetable oil is naturally occurring oil and is thus excellent in biodegradability and superior in respect of lower prices, but it is poor in oxidative stability, and because the conventional hydraulic oil using said vegetable oil as the base oil has the problems of its easily increasing viscosity during its use, easy formation of sludge, etc., it is difficult to use the conventional hydraulic oil under severe environments such as high temperatures, high loading and the like.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a hydraulic oil composition comprising vegetable oil as base oil, which is excellent in oxidative stability, lubricating properties and biodegradability.
The biodegradable hydraulic oil composition of the present invention was made by paying attention to a combination of vegetable oil having a specific degree of unsaturation and specific additives in order to solve the problem described above.
That is, the first aspect of the invention relates to a hydraulic oil composition comprising vegetable oil with a total degree of unsaturation of 0.3 or less as base oil, and comprising at least one antioxidant selected from the group consisting of a phenol antioxidant, an amine antioxidant and a zinc dithiophosphate antioxidant in an amount of 0.01 to 5% by mass based on the total amount of the composition.
The second aspect of the present invention relates to the hydraulic oil composition described above, wherein said vegetable oil has an oleic acid content of not less than 70% by mass in triglyceride-constituting fatty acids.
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention is described in detail.
The base oil in the hydraulic oil composition of the present invention is vegetable oil with a total degree of unsaturation of 0.3 or less. Preferably, vegetable oil with a total degree of unsaturation of 0.2 or less can be used. If the total degree of unsaturation of the base oil used is higher than 0.3, the hydraulic oil composition of the present invention becomes inferior in oxidative stability, which is not preferable. The total degree of unsaturation referred to in the present invention means a total degree of unsaturation measured using the same device and procedure as those used in the “Polyether for Polyurethane Test Method” in JIS K1557-1970 except that vegetable oil is used in place of a polyether for polyurethane.
Further, the base oil in the present invention is preferably vegetable oil with an oleic acid content of not less than 70% by mass, more preferably not less than 80% by mass in triglyceride-constituting fatty acids. By using the vegetable oil with an oleic acid content of not less than 70% by mass, further improved oxidative stability of the composition can be achieved and further improvement in abrasion resistance is also achieved. The oleic acid content in vegetable oil referred to in the present invention means a content of oleic acid measured according to “2.4.2 Composition of Fatty Acid” in the Standard Methods for Analysis of Fats and Oils stipulated by the Japanese Society of Oil Chemistry.
According to the present invention, the kinematic viscosity of said vegetable oil is arbitrary and not particularly limited, but from the viewpoint of good lubricating properties and cooling properties (heat removability) and of less frictional loss by resistance to stirring, the kinematic viscosity thereof at 40° C. is preferably 10 to 10000 mm
2
/s, more preferably 20 to 1000 mm
2
/s.
The viscosity index of said vegetable oil is also arbitrary, and but for preventing a reduction of oil film thickness at high temperatures, the viscosity index thereof is preferably 50 to 500, more preferably 90 to 300. The pour point of said vegetable oil is also arbitrary, but in view of starting property of a pump in winter, generally the pour point thereof is preferably 0° C. or less, more preferably −5° C. or less.
The flash point of said vegetable oil is also arbitrary, but in view of the possibility of fire, the flash point is preferably 70° C. or more, more preferably 200° C. or more. The total acid value of said vegetable oil is also arbitrary and not particularly limited, but if a too large amount of free fatty acids are present as impurities, the hydraulic oil composition may be lowered in the oxidative stability and thus the total acid value is 0 to 2.0 mg KOH/g, more preferably 0 to 0.5 mg KOH/g.
A process for producing said vegetable oil used in the present invention is not particularly limited and any arbitrary processes are available as long as vegetable oil to be produced by said processes has properties as mentioned above. For instance, natural vegetable oil having a total degree of unsaturation of 0.3 or less can be used in the present invention as it is.
Further, there are a large number of natural vegetable oils having a total degree of unsaturation of over 0.3, and in a process of refining them, the total degree of unsaturation can be reduced by hydrogenation or the like.
It is also possible to obtain vegetable oil having a total degree of unsaturation of 0.3 or less by carrying out breeding (plant breeding) of natural vegetables or carrying out genetic recombination of natural vegetables, and vegetable oil thus obtained can also be used in the present invention. It is described that vegetable oil having a low total degree of unsaturation can be easily produced by genetic recombination technology in Japanese National Phase Laid-Open Gazette No. Hei 11-508961 (publication date: Aug. 3, 1999) entitled “Soybean Oil Having High Oxidative Stability.”
It is also possible to obtain vegetable oil having a high oleic acid content in triglyceride as well as having a low total degree of unsaturation by said breeding (plant breeding) or genetic recombination of natural vegetables.
The type of vegetable oil used in the present invention is not particularly limited, but rapeseed oil, sunflower oil, soybean oil, corn oil, canola oil, mixed oil thereof and oil obtained by hydrogenating them can be preferably used Further, rapeseed oil, sunflower oil, soybean oil, corn oil, canola oil, which are obtained by breeding (plant breeding) or genetic recombination, can also be used. Among them, sunflower oil, soybean oil, and sunflower oil and soybean oil which are obtained by breeding (plant breeding) or genetic recombination, can be preferably used.
According to the present invention, mineral oil and synthetic oil (diester, polyol ester etc.) can be contained as base oil in the hydraulic oil composition. The content of mineral oil is preferably 20% by mass or less, and the content of synthetic oil is 50% by mass or less, relative to the total amount of the base oil. Examples of diesters of said synthetic oil are dioctyl adipate, dioctyl phthalate, dioctyl sebacate etc., and examples of polyol esters are trimethylol propane ester such as trimethylol propane trioleate etc., pentaerythritol ester such as pentaerythritol tetraoleate etc., and neopentyl glycol ester such as neopentyl glycol dioleate and the like.
The hydraulic oil composition of the present invention comprises at least one antioxidant selected from the group consisting of a phenol antioxidant, an amine antioxidant and a zinc dithiophospha
Kikuchi Yoshinobu
Konishi Toru
Howard Jacqueline V.
Kubovcik & Kubovcik
Nippon Mitsubishi Oil Corporation
LandOfFree
Hydraulic oil composition does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hydraulic oil composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hydraulic oil composition will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2575834