Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic compound containing boron
Reexamination Certificate
1999-07-09
2003-10-28
Howard, Jacqueline V. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic compound containing boron
C508S232000, C508S287000, C508S460000
Reexamination Certificate
active
06638897
ABSTRACT:
FIELD OF INDUSTRIAL UTILIZATION
This invention relates to a lubricant oil composition, more particularly a lubricating oil composition of longer service interval for internal combustion engines, in particular diesel engines, which are equipped with a filtration means, e.g., oil filter, to efficiently capture and remove agglomerated solid impurities, e.g., soot inevitably produced while a diesel engine is driven.
BACKGROUND OF THE INVENTION
Lubricant oils have been used for internal combustion engines to lubricate various members, e.g., piston rings, cylinder liners, bearings for crank shafts and connecting rods, valve train mechanisms including cams and valve lifters, and other reciprocating lubrication regime. In addition to the lubricating purposes above described, they are also used for cooling engines, cleaning and dispersing combustion products, and prevention of rust and corrosion.
As described above, lubricant oils for internal combustion engines are required to exhibit a variety of functions. These requirements are becoming more severe, as the engines become more functional, produce higher power and are operated under more severe conditions. In order to satisfy these requirements, lubricant base oils for internal combustion engines are incorporated with a variety of additives, such as ashless dispersant, metallic detergent, antiwear agent, friction reducing agent and antioxidant.
Lubricant oils for internal combustion engines have been incorporated with a combination of ashless dispersant and metallic detergent. The ashless dispersants generally include those based on polyalkenyl or polyalkyl succinamide, polyalkenyl or polyalkyl succinic acid ester, polyalkenyl or polyalkyl benzyl amine. These compounds may be treated with boron. On the other hand, the metallic detergents generally include those based on phenate, sulfonates, salicylates and phosphonates of alkali and alkali-earth metals. These compounds may be overbased.
A diesel engine structurally produces larger quantities of solid impurities insoluble in lubricant oil, e.g., combustion residue and soot, than does a gasoline engine, and causes contamination of the lubricant oil and lubricating systems with them. Various problems will occur as the extent of the contamination increases, e.g., sharply increased viscosity of the lubricant oil and at the rubbing surfaces of the engine parts, and clogging in the lubricating systems, preventing smooth control of lubrication and needing frequent replacement of lubricating oil.
A variety of measures and means have been proposed to remove solid impurities insoluble in lubricating oil, e.g., combustion residue and soot, in order to solve these problems. These measures and means fall into the following two general categories:
The first category is to agglomerate the solid impurities to make them coarser, and capture and remove them by an oil filter installed in a lubricating oil recycling system. This concept leads to development of lubricating oils incorporated with calcium phenate of specific total base number, magnesium sulfonate of specific total base number or alkenyl succinimide to agglomerate solid impurities (Japanese Patent Publication No. 3-29839, and Japanese Laid-open Patent Application No. 5-295382); and lubricating systems for diesel engines, which use lubricating oil compositions incorporated with two types of calcium sulfonate of specific total base number, calcium phenate of specific total base number, alkenyl succinimide or zinc dithiophospate (Japanese Patent Publication No. 6-60317). Those based on the similar technical concept include diesel engine oils incorporated with a hydroxyethyl thiophosphonate ester or the like to help remove the combustion residue by an oil filter while keeping adequate dispersibility (Japanese Laid-open Patent Application No. 4-1293 and No. 5-93197); and overland diesel engine oils incorporated with a combination of succinimide and long-chain zinc dialkyl dithiophosphate to help remove solid impurities while controlling dispersibility (Japanese Laid-open Patent Application No. 5-230485).
The second category, different from the first category in basic concepts, tries to prevent agglomeration of solid impurities, e.g., soot, in oil and disperse the solid impurities themselves finely in oil. Specifically, the proposed techniques falling into this category include diesel engine oils incorporated with calcium phenate of specific total base number, alkenyl succinimide or specific zinc dithiophosphate which are capable of controlling particle size of soot (Japanese Laid-open Patent Application No. 9-165591); and lubricants incorporated with a transition metal salt to directly control soot (Japanese Laid-open Patent Application No. 1-501396).
Low-phosphorus, low-ash type diesel engine oils are also proposed for diesel engines equipped with a diesel particulate filter (DPF). They are incorporated with a specific content of zinc dialkyl dithiophosphate, calcium salicylate overbased with calcium carbonate and having a specific total base number and/or calcium salicylate overbased with calcium borate, or boron-modified succinimide having a specific molecular weight (Japanese Laid-open Patent Application No. 9-111275).
Few of the above techniques, however, provide lubricating oil systems of satisfactory serviceability for diesel engines. In particular, all of the techniques falling in the first category fail to efficiently capture and remove agglomerated solid impurities (e.g., soot) by a filter means (e.g., oil filter) while keeping long serviceability for diesel engines.
The present invention provides a lubricant oil composition of longer service interval for internal combustion engines, exhibiting an excellent effect of agglomerating solid impurity particles it contains to a sufficiently large size as to be captured and removed by an oil filter.
DESCRIPTION OF THE INVENTION
The present invention is directed to a lubricant oil composition comprising a base oil composed of a mineral oil, synthetic oil or mixtures thereof which can agglomerate solid impurities (e.g., soot) to make them sufficiently coarser, when the base oil is incorporated with specific contents of calcium salicylate overbased with calcium carbonate and succinimide having a specific weight-average molecular weight.
In the first aspect the invention provides a lubricant oil composition for internal combustion engines, comprising a base oil composed of a mineral oil, synthetic oil or mixture thereof which is incorporated with (A) calcium salicylate overbased with calcium carbonate and having a total base number of 30 to 350 mgKOH/g at 0.10 to 0.90 wt % (as calcium), and (B) a succinimide selected from the group consisting of boron-containing succinimide having a weight-average molecular weight of 3,000 or less at 0.04 wt % or less (as boron derived from the boron-containing succinimide), succinimide having a weight-average molecular weight of 2,500 or less at 0.01 to 0.25 wt % (as nitrogen), and mixtures hereof the above percentages being based on the whole composition.
Further, in the second aspect the invention provides a lubricant oil composition for internal combustion engines, comprising a base oil composed of a mineral oil synthetic oil or mixture thereof which is incorporated with (A) calcium salicylate overbased with calcium carbonate and having a total base number of 30 to 100 mgKOH/g at 0.05 to 0.90 wt % (as calcium), and (B) a succinimide selected from the group consisting of boron-containing succinimide having a weight-average molecular weight of 3,000 or less at 0.04 wt % or less (as boron derived from the boron-containing succinimide), succinimide having a weight-average molecular weight of 3,000 or less at 0.01 to 0.25 wt % (as nitrogen) thereof and mixtures, the above percentages being based on the whole composition.
As described above, the present invention provides a lubricant oil composition for internal combustion engines, comprising a base oil incorporated with specific contents of calcium salicylate overbased with calcium carbonate and succinimide having
Kawagoishi Nobuchika
Kuribayashi Toshiaki
Ogano Satoshi
Yoneda Makota
Foss Norby L.
Howard Jacqueline V.
TonenGeneral Sekiyu K.K.
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