JPH027359B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a multigrade lubricating oil composition for turbocharged engines, and more particularly to a multigrade engine oil composition for turbocharged engines that produces less deposits (carbon deposits). The production volume of passenger cars equipped with turbocharged engines (hereinafter referred to as ``turbo cars'') has been rapidly increasing in recent years, and is expected to account for 10% of the total production volume in fiscal 1988. Currently, high-performance engine oils (usually
API service classification SE oil or SF oil) is used, but the recommended oil change distance is approximately half that of a regular engine. This is because the turbocharger is exposed to high-temperature residual heat, which poses a risk of oil deterioration (particularly the formation of deposits due to oil coking within the turbocharger). When a turbocharged engine is operated at high speed and high load and then suddenly stopped, that is, when the turbocharger heat soaks back,
The turbine side wall temperature reaches over 300°C, and coking of engine oil occurs within the turbocharger. As a result, the oil flow path may become blocked, causing the floating metal to seize, or deposits from caulking to enter between the floating metal and the shaft, causing the floating metal to move abnormally, or causing the floating metal to wear out. , the turbine blades and compressor blades come into contact with the casing, causing problems such as damage. Multigrade oils are now widely used in engine oils instead of single grade oils. This is because multigrade oil has better low-temperature startability than single-grade oil, and in summer,
This is because it can be used in all seasons, including winter, and is superior in many respects, including good fuel efficiency. However, when this multigrade oil is used in a turbocharged engine,
It was found that the coking of the oil was more pronounced and a large amount of deposits were formed compared to the single grade oil. Generally, when preparing multigrade oils, such as the 10W-30 grade, the kinematic viscosity is typically 5 cst (100
3 to 10% by weight of a viscosity index improver, which is a polymeric compound such as polymethacrylate or olefin copolymer, is added to the base oil. However, this viscosity index improver is said to be a cause of deposit formation when multigrade oils are used in turbocharged engines. Therefore, a multigrade oil with good thermal stability and oxidation stability is required for turbocharged engines, but such an oil has not yet been developed. Therefore, the present inventors conducted repeated research to develop a multigrade oil suitable for turbocharged engines, and as a result, they completed the present invention. An object of the present invention is to provide a multigrade lubricating oil composition for a turbocharged engine that maintains the excellent properties of multigrade oils and also generates less deposits due to coking. That is, the present invention uses mineral oil and/or one or more synthetic oils selected from poly-α-olefin oil, diester oil, and polyol ester oil as the base oil, and (A ) Mineral oil and/or poly-α-olefin oil having a kinematic viscosity of 16 to 45 cst (100°C) 3 to 40% by weight, and (B) 0.5 to 15% by weight of a viscosity index improver as essential components. The present invention provides a multigrade engine oil composition for turbocharged engines. Hereinafter, the content of the present invention will be explained in detail. The base oil in the composition of the present invention has a kinematic viscosity of 1.5 to
13cst (100°C) mineral and/or synthetic oils, which are commonly used as base oils for conventional multigrade engine oils. The mineral oil is a lubricating oil fraction obtained as a distillate by vacuum distillation of the residual oil from atmospheric distillation of crude oil, or this fraction is further subjected to solvent extraction, solvent dewaxing, sulfuric acid washing, clay treatment, and hydrofinishing. Refined mineral oils refined by , hydrotreating, or a combination thereof, with a kinematic viscosity of 1.5 to 13cst (100°C), can be used. Furthermore, any mineral oil having a viscosity within this range may be mixed and used as the base oil. These mineral oils generally preferably have a viscosity index of 50 to 120. On the other hand, as the synthetic oil, poly-α-olefin oil, diester oil, or polyol ester oil with a kinematic viscosity of 1.5 to 13 cst can be used. More specifically, as a synthetic oil, for example, a carbon number of 4 to 12
Polybutene obtained by homopolymerization or copolymerization of α-olefin, poly-α-olefin oil such as poly-1-decene, di-2-ethylhexyl sebacate, dioctyl adipate, ditridecyl glutarate, ditridecyl adipate, etc. Typical diester oils of dibasic acids and monohydric alcohols, trimethylolpropane caprylate, trimethylolpropane caprylate, trimethylolpropane pelagonate, pentaerythritol-2-ethylhexanoate, pentaerythritol pelargonate, etc. Typical examples include polyol ester oils and mixtures thereof. In addition, in the present invention, as the base oil, a mixture of the mineral oil and the synthetic oil in any proportion can be used as necessary. In the present invention, component (A) has a kinematic viscosity of 16 to 45 cst.
(100°C) mineral oil and/or poly-α-olefin oil. Mineral oils and polyesters in this viscosity range
Since α-olefin oil has a high viscosity, it has not been used as a multigrade engine oil until now. Mineral oils include heavy lubricating oils obtained by solvent deasphalting the residual oil (bottom oil) collected during vacuum distillation of atmospheric distillation residual oil of crude oil, or solvent extraction and solvent dewaxing of this. Refined heavy mineral oils with a kinematic viscosity of 16 to 45cst (100°C) can be used, refined by sulfuric acid washing, clay treatment, hydrofinishing, hydrogenation treatment, or a combination of these. Furthermore, any mineral oil having a viscosity within this range may be mixed and used. On the other hand, as poly-α-olefin oil,
For example, poly-α-olefin oils such as polybutene and poly-1-decene obtained by homopolymerization or copolymerization of α-olefins having 4 to 12 carbon atoms, with a kinematic viscosity of 16 to 45 cst (100°C) are used. be done. Further, in the present invention, a mixture of the mineral oil and poly-α-olefin oil in any ratio can also be used as component (A). Component (B) in the present invention is a viscosity index improver,
Commercially available or generally known materials can be used. Specifically, such viscosity index improvers include (1) polymerized at least one ester of methacrylic acid and a saturated monovalent linear or branched aliphatic alcohol having 1 to 18 carbon atoms; Polymethacrylate (non-dispersed type) with an average molecular weight of 20,000 to 200,000 obtained by
Average molecular weight obtained by copolymerization with polar vinyl compounds such as vinylpyridine, N-vinylpyrrolidinone, polyalkylene glycol ester of methacrylic acid, or maleic anhydride.
20,000 to 200,000 polymethacrylate (dispersed type), (2) obtained by polymerizing one or more compounds selected from olefins having 2 to 5 carbon atoms, diolefins having 2 to 5 carbon atoms, and aromatic vinyl compounds. polymers having an average molecular weight of 10,000 to 200,000, preferably 20,000 to 1,000,000, or hydrides thereof (for example, ethylene-propylene copolymers, isobutylene homopolymers, alkylstyrene homopolymers, butadiene-styrene copolymers hydrides, Isobutylene homopolymer hydride,
Hydrogenated isoprene-styrene copolymers, etc.) and mixtures thereof, but polymethacrylate (non-dispersed type, dispersed type), ethylene-propylene copolymers, isoprene-styrene copolymers, etc. Polymeric hydrides and mixtures thereof are preferred. Since these viscosity index improvers are solids, they are usually used in the form of viscous solutions dissolved in solvents or mineral oil. In the composition of the present invention, the content of component (A) is 3
~40% by weight, preferably 10-30% by weight. (A)
If the content of the component does not reach this range, the effect of preventing coking by adding component (A) will be small, while if the content of component (A) exceeds this range, the low-temperature viscosity of the composition will increase. In addition, the residual carbon content of the composition increases, which is undesirable because it promotes engine fouling. Further, in the composition of the present invention, the content of component (B) is 0.5 to 15% by weight. If the content of component (B) does not reach this range, the composition cannot be multigrade, while if the content of component (B) exceeds this range, the composition will cause severe coking. This is not desirable. In the present invention, in addition to the viscosity index improver, various known additives may be added as necessary, such as zinc dialkyldithiophosphate, alkaline earth metal sulfonate, alkaline earth metal phenate, alkaline earth metal phosphonate, and succinimide. , cleaning and dispersing agents such as succinic acid esters and benzylamine, phenolic and amine antioxidants,
Various rust inhibitors, metal deactivators such as benzotriazole, defrosting agents, various friction modifiers, and the like can be added singly or in combination of two or more. The selection and addition amount of these additives are arbitrary and are appropriately determined according to the quality grade of the API service classification of the engine oil. The present invention provides a multigrade lubricating oil composition for turbocharged engines that produces less deposits due to coking. The formation of deposits due to coking is also affected by the additives mentioned above, and it is possible to reduce the formation of deposits to a certain extent by appropriately selecting additives, but if the composition of the present invention is used, It is possible to suppress the generation of deposits to a level that could not be reached. Furthermore, based on the present invention, by mixing prescribed amounts of base oil, component (A), and component (B) as essential components, it is possible to produce products with various viscosities, such as
5W−30, 10W−30, 10W−40, 15W−30, 15W
A multigrade lubricating oil composition for turbocharged engines having an SAE viscosity grade such as -40 is obtained. The contents of the present invention will be explained in more detail below with reference to Examples and Comparative Examples. However, the present invention is not limited to these Examples. Examples 1 to 9 and Comparative Examples 1 to 6 Multigrade lubricating oil compositions (Examples 1 to 9) based on the present invention were obtained according to the compositions listed in Table 1, and their evaluation was performed using the Tentative test method of Federal 791.
The panel caulking test was conducted in accordance with Standard Method 3462-T. Test conditions are panel temperature
310℃, oil temperature 100℃, splash bar stops in 15 seconds45
seconds, test time is 24 hours. The results are shown in Table 1. For comparison, when component (A) is not used (corresponding to conventional multigrade oil; Comparative Examples 1 and 2),
Similar panel coking tests were conducted on mineral oil-based commercially available multigrade engine oils (Comparative Examples 3 to 5) and synthetic oil-based commercially available multigrade engine oils. The results are shown in Table 2. The substances in the compositions of Tables 1 and 2 are as follows. ● Base oil; Refined mineral oil a: Kinematic viscosity 2.0 cst (100°C) B: Kinematic viscosity 4.5 cst (100°C) Refined mineral oil C: Kinematic viscosity 7.0 cst (100°C) d: Kinematic viscosity 11 cst (100°C) Poly -α-olefin oil e: Kinematic viscosity 4.0 cst (100
1-decene oligomer (A) component; Refined heavy mineral oil f: Kinematic viscosity 22cst (100°C) g: Kinematic viscosity 32cst (100°C) Poly-α-olefin oil h: Kinematic viscosity 40cst (100°C)
℃) 1-decene oligomer ● (B) component; Ethylene-propylene copolymer: average molecular weight
35000 Polymethacrylate: Polymerized ester of methacrylic acid and a saturated aliphatic monohydric alcohol mixture having 1 to 18 carbon atoms (average molecular weight 78000). Isoprene-styrene copolymer hydride: average molecular weight 95000 ● Additive package i to k; anti-wear agent, cleaning dispersant, antioxidant, rust inhibitor, metal deactivator, defrost agent, friction modifier, etc. A packaged version of various additives. As is clear from the results in Tables 1 and 2, the multigrade lubricating oil compositions according to the present invention (Examples 1 to 9) are different from those in which component (A) is not used (Comparative Examples 1 and 2) and commercially available Compared to the multigrade engine oils (Comparative Examples 2 to 6), the amount of deposits formed in the panel coking test was significantly reduced, and the oils had excellent properties.

【table】

[Table] Examples 10 to 13 Using diester oil or polyol ester oil as the base oil, engine oil compositions having the compositions shown in Table 3 were obtained and tested in the same manner as in Examples 1 to 9. Good results were obtained. The results are shown in Table-3.

【table】

【table】

Claims (1)

[Claims] 1. Mineral oil with a kinematic viscosity of 1.5 to 13cst (100°C) and/or one or more synthetic oils selected from poly-α-olefin oil, diester oil, and polyol ester oil as the base oil. , (A) 3 to 40% by weight of mineral oil and/or poly-α-olefin oil with a kinematic viscosity of 16 to 45cst (100°C), and (B) 0.5 to 15% by weight of a viscosity index improver, as essential components. A multi-grade engine oil composition for turbocharged engines.