JPH0673389A - Lubricant containing water-repellent silica colloid - Google Patents

Abstract

PURPOSE:To develop a general-purpose lubricant which is excellent in resistances to seizure and abrasion and rarely causes the corrosion of a friction surface and the shortening of the service life of the lubricant due to its oxidation. CONSTITUTION:This lubricant comprises a base oil and a water-repellent silica colloid contained therein in an amt. pref. of 0.001-10wt.% in terms of silica. The pref. water-repellent silica colloid has a degree of hydrophobization of at least 50% and a particle diameter of up to 100nm and is obtd. by silylating a silica colloid with a silane compd. having a 12C or higher alkyl group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricant containing a water-repellent silica colloid, and more specifically, it has excellent seizure resistance and wear resistance, and is resistant to corrosion on the friction surface and reduction in life due to oxidation of the lubricant. It relates to a general-purpose lubricant.

[0002]

2. Description of the Related Art Conventionally, as a means for imparting seizure resistance and wear resistance to lubricants, particularly oils on sliding surfaces and lubricants used under medium to high load conditions. Is known to blend extreme pressure agents and oiliness agents into base oils (Chemical Handbook, Applied Chemistry II, Materials, 1218).
~ 1219 pages, issued October 15, 1986). In this case, various extreme pressure agents such as phosphorus-based, sulfur-based, chlorine-based, and organometallic compound-based agents, and oiliness agents such as fatty acids, oils and fats, long-chain alcohols, molybdenum dialkyldithiophosphates, polyvalent Alcohol half-esters, amines, amides, sulfurized esters and the like are used, and these are usually blended in an amount of about 0.5 to 5% by weight with respect to the base oil.

However, since these extreme pressure agents and oiliness agents basically impart seizure resistance and abrasion resistance due to the formation of an adsorption film on the friction surface or the reaction product with the friction surface, When the compounding amount is increased for the purpose of improving the seizure property and the wear resistance, there is a problem that the friction surface is corroded. In addition, when a large amount of extreme pressure agent or oiliness agent is blended, there is a problem in that the base oil is oxidized and the life of the lubricant is shortened. From such a viewpoint, the present inventors have conducted earnest studies to develop a lubricant which is excellent in seizure resistance and wear resistance and which is less likely to cause the above-mentioned corrosion and the deterioration of the life of the lubricant.

[0004]

As a result, a lubricant obtained by compounding a silica colloid whose physical and chemical reactivity with respect to a friction surface and a base oil is reduced by applying a water repellent treatment, It has been found that it has excellent seizure resistance and wear resistance, and that it is less likely to cause corrosion and shorten the life of the lubricant. The present invention has been completed based on such findings. That is, the present invention provides a lubricant characterized by comprising a water-repellent silica colloid in a base oil.

As the base oil used in the present invention, various mineral oils or synthetic oils conventionally used as lubricant base oils can be used. The viscosity and the like can be arbitrarily selected. For example, as mineral oil, paraffin-based, intermediate-based,
Mention may be made of various mineral oils such as naphthenic bases. Further, as synthetic oils, hydrocarbon type (polybutene, α-olefin oligomer, etc.), polyalkylene glycol type (polyethylene glycol, polypropylene glycol, etc.),
Diester type (di-2-ethylhexyl sebacate, di-2-ethylhexyl adipate, etc.), polyol ester type (pentaerythritol ester, trimethylolpropane ester, etc.), phosphate ester type (tricresyl phosphate, propylphenyl phosphate, etc.) , Silicate ester type (tetraoctyl silicate, tetradecyl silicate, etc.), Silicone type (dimethyl silicone, etc.),
Examples include synthetic oils such as polyphenyl ether type (m-bis (m-phenoxyphenoxy) benzene etc.) and fluorinated hydrocarbon type (polychlorotrifluoroethylene etc.). In addition, these mineral oils and synthetic oils may be used alone or in combination at an arbitrary ratio.

Next, the water-repellent silica colloid used in the present invention can be obtained by subjecting the silica colloid to a water-repellent treatment by a method conventionally used. Here, silica means silicon dioxide (SiO ₂ ), and silica colloid means fine particles of amorphous silica which can be stably dispersed in an aqueous solvent or an organic solvent.

Various methods can be applied to obtain the water-repellent silica colloid. For example, in water-dispersed silica colloid,
Non-polar organic solvent (benzene, toluene, xylene, ethylbenzene, cumene, cyclohexane, ethylcyclohexane, decalin, hydrocarbons such as pentane, heptane, octane, industrial gasoline such as mineral spirit, petroleum solvent such as kerosene, petrochemical system Solvent or mixture thereof), cationic surfactant (alkylamine salt, polyamine and aminoalcohol fatty acid derivative, alkyl quaternary ammonium salt (alkyl trimethyl ammonium, etc.), cyclic quaternary ammonium salt (alkyl pyridinium salt, etc.), hydroxyl group A quaternary ammonium salt having a quaternary ammonium salt, a quaternary ammonium salt having an ether bond, a quaternary ammonium salt having an amide) and a silylating agent to form an emulsion, and then water is removed by azeotropic dehydration, followed by heating under reflux. By , It can be efficiently obtained Bachisuisei colloidal silica. In addition, a method of reacting silica with vapor of an organic halogenated silicon compound at high temperature (dry method)
And alkyltrialkoxysilanes are mixed with water and optionally an acid and then added to the silica aquasol to pre-hydrolyze the alkyltrialkoxysilanes and pre-hydrolyzed alkyltrialkoxysilanes and silricaqua The water-repellent silica colloid can also be obtained by a method of performing a reaction with a sol (wet method).
The water-repellent silica colloid thus obtained improves the seizure resistance and wear resistance of the lubricant by being mixed with the base oil, while at the same time having physical and chemical reactivity with the friction surface and the base oil. Since it is low, the service life is less likely to decrease due to corrosion of the friction surface and oxidation of the lubricant.

The amount of the water-repellent silica colloid to be added to the base oil can be arbitrarily selected according to the use as a lubricant, and is not particularly limited, but the water-repellent silica colloid is added to the silica based on the total weight of the lubricant. The amount is preferably 0.0001 to 10% by weight, particularly 0.001 to 1% by weight.
If the amount of silica is less than 0.0001% by weight, the effect of seizure resistance may decrease, while if it exceeds 10% by weight, the effect of abrasion resistance may decrease.

The properties of the water-repellent silica colloid vary depending on the properties of the silica colloid used as a raw material, the water-repellent treatment method, the conditions, etc., but the properties of the water-repellent silica colloid are not particularly limited in the present invention. not,
Any one can be used. However, it is usually preferable to use the one having a certain range of hydrophobicity and / or particle size. That is, the hydrophobicity of the water-repellent silica colloid is preferably 50% or more, more preferably 70% or more, still more preferably 90% or more. Here, the hydrophobicity ratio is N _RSi / N _OH × 100 (wherein, N _OH is the total number of hydroxyl groups on the surface of the silica colloid particles, and N _RSi is an alkyl-substituted silyl group bonded to the hydroxyl groups on the surface of the silica colloid particles. (Indicated)). On the other hand, the particle size of the water-repellent silica colloid is preferably 100 nm or less. Hydrophobicity is less than 50% or particle size is 100 nm
If it exceeds, the dispersibility of the water-repellent silica colloid in the base oil may decrease.

Suitable water-repellent silica colloids in view of such hydrophobicity and particle size are obtained by silylating silica colloids with higher alkyl-substituted silanes having 12 or more carbon atoms, preferably 12 to 30 carbon atoms. Water repellent silica colloids may be mentioned. Examples of the alkyl-substituted silanes include, for example, simple alkyl-substituted silanes substituted with only an alkyl group, alkyl-substituted halosilanes (octadecyltrichlorosilane, octadecylmethyldichlorosilane, octadecyldimethylchlorosilane, etc.), alkyl-substituted alkoxysilanes (octadecyltrichlorosilane, etc.). Methoxysilane, octadecylmethyldimethoxysilane, octadecyldimethylmethoxysilane, etc.), alkyl-substituted silazanes, and hydroxysilanes obtained by hydrolyzing these, and the like. Higher carbon number 12 or more used in the above silylation. The alkyl-substituted silanes are those having an alkyl group having 12 or more carbon atoms in the alkyl group bonded to the alkyl-substituted silanes.
The alkyl group having 12 or more carbon atoms preferably accounts for 50 mol% or more of the total alkyl groups bonded to the alkyl-substituted silanes, and particularly preferably 80 mol% or more. If it is less than 50 mol%, it is difficult to obtain a good hydrophobicity.

The lubricant of the present invention contains the above-mentioned base oil and water-repellent silica colloid as the main components, but if necessary, various additives used in conventional lubricants can be added. . For example, load-bearing additives, antioxidants (phenolic, amine-based), rust preventives (half ester, etc.), corrosion inhibitors, detergent dispersants, viscosity index improvers, pour point depressants, defoamers, etc. Can be blended as required, and phosphorus (tricresyl phosphate, tributyl phosphite, etc.), sulfur (sulfurized oil and fat, dibenzyl disulfide, etc.), chlorine (chlorinated paraffin, etc.), organometallic compound Various extreme pressure agents such as type (ZnDTP, lead naphthenate, etc.), fatty acids (oleic acid, stearic acid, etc.),
An oiliness agent such as oil and fat (beef tallow, lard, etc.), long-chain alcohol (lauryl alcohol, etc.), molybdenum dialkyldithiophosphate, polyhydric alcohol half ester, amine, amide, sulfurized ester and the like can be blended.

The lubricant of the present invention can be obtained by blending and dispersing a water-repellent silica colloid in the above base oil, and optionally blending other additives. A usual method can be adopted for dispersing the water-repellent silica colloid,
For example, a water-repellent silica colloid may be added to a small amount of base oil, heated and stirred to form a collesent, and then the remaining base oil may be added and diluted and mixed. The order of blending other additives in addition to the water-repellent silica colloid is appropriately determined according to the properties of each additive.

[0013]

EXAMPLES Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. Preparation Example of Water-Repellent Silica Colloid Commercially available water-dispersed silica colloid (Catalyst Kasei Co., Ltd., trade name: S-20L, SiO ₂ concentration 20%) 50 g toluene 400 g toluene commercially available cationic surfactant (Kao (stock) )
Product name: Coatamine D86P, surfactant concentration 20
%) And 7.5 g of octadecyltrimethoxysilane as a silylating agent, and the mixture was stirred and mixed with a homogenizer for 10 minutes to prepare an emulsion liquid. This emulsion solution was placed in a 1-liter three-necked flask equipped with a stirrer, a cooler, and a distillation device, and the temperature was adjusted to about 1 while watching the steam temperature under continuous stirring.
Time azeotropic dehydration distillation was performed. When the vapor temperature reaches the boiling point of toluene (110.6 ° C), the distillation is stopped, the reflux route is switched, and the mixture is heated and refluxed for 2 hours. The water-repellent silica colloid in a sol state dispersed in toluene (water-repellent silica sol)
200 g was obtained. As a result of analyzing the obtained water-repellent silica sol, the SiO ₂ concentration was 5.0% by weight (gravimetric analysis), the hydrophobization rate was 97% (quantification by liquid chromatography), p
H was 7.5 and the colloidal particle size was 40 nm (light scattering method). 1 g of this water-repellent silica sol is applied to a JIS 1-3 mortar plate (100 × 100 × 10 mm), dried at room temperature for 1 day, and then a drop of water (0.03 cc) is dripped to measure the diameter of the water drop. When measured, it was 5.2 mm, confirming excellent water repellency. For comparison, one drop (0.03 cc) of water was dropped with a dropper onto a JIS 1-3 mortar plate to which the water-repellent silica sol was not applied, and the diameter of the water drop was 12.2 mm. Furthermore, this water-repellent silica sol was put in a 100 cc sample bottle and allowed to stand at room temperature for 30 days, and the change with time of the colloidal particle diameter was traced by a light scattering method. As a result, the particle size after 30 days was 42 nm, which was almost unchanged from 40 nm at the time of preparation,
The temporal stability of the water-repellent silica sol was confirmed.

Example 1 Based on the total weight of the lubricant, mineral oil (Idemitsu Kosan Co., Ltd.,
150 neutral oil) to 95% by weight of water-repellent silica colloid (hydrophobicity 97%) 5 obtained in the above preparation example.
Lubricants were obtained by blending wt%. A seizure resistance test and an abrasion resistance test were performed on the obtained lubricant. The friction coefficient was measured using a reciprocating friction tester. The results are shown in Table 1.

Examples 2-5 As shown in Table 1, a water-repellent silica colloid was added to 0.00
The same operation as in Example 1 was performed except that the amount was 1 to 1% by weight, and each test was performed on the obtained lubricant.

Examples 6 to 9 As shown in Table 1, 0.1% by weight of a water-repellent silica colloid was added, and tricresyl phosphate, sulfurized oil and fat, ZnDTP or R & O (antioxidant and anticorrosive agent) were added. The same operation as in Example 1 was carried out except that the above components were added, and each test was conducted on the obtained lubricant.

Comparative Example 1 As shown in Table 1, each test was conducted only on the base oil.

Comparative Examples 2 to 11 As shown in Table 1, silica colloid 1 (Catalyst Kasei Co., Ltd., trade name: S-20L, SiO ₂ concentration 20%) was used without adding water-repellent silica colloid. ), Silica colloid 2 (manufactured by Nippon Aerosil Co., Ltd., trade name: AEROS)
IL200), silica colloid 3 (manufactured by Nippon Aerosil Co., Ltd., trade name: AEROSIL R974D), silica colloid 4 (manufactured by Nippon Aerosil Co., Ltd., trade name: A
EROSILR 805), OMS (manufactured by Toshiba Silicone Co., Ltd., trade name: TSL8185), tricresyl phosphate, sulfurized oil and fat, ZnDTP or R & O (a mixture of an antioxidant and an anticorrosive agent) was used in the same manner as in Example 1. An operation was performed and each test was performed on the obtained lubricant.

The above tests were carried out by the following test methods. (1) Seizure resistance test Block-on-disc type friction tester (Falex,
LFW-1 tester is used and block (width 6.
35 mm, SAE01 steel, hardness (Rc) 60, surface roughness (Rrms) 0.15 μm) and ring (diameter 35 mm, SA
E4620 steel, Rc60, Rrms 0.22 μm) using a test piece, oil bath refueling, oil amount 120 ml, 100
A load (Lbs) at the time of seizure was measured by applying a stepwise load of 20 Lbs for 3 minutes under conditions of a temperature of 2 ° C. and a sliding speed of 2 m / sec. (2) Abrasion resistance test A test was performed using the same tester, test piece, and test conditions as the above seizure resistance test, and the abrasion volume of the friction surface of the block after 100 Lbs x 60 minutes was measured. (3) Measurement of reciprocating low speed sliding friction coefficient Using a reciprocating friction tester (Bowden type), the steel balls are SUJ
-2 (1/2 inch ball, Rc61), steel plate is SUJ-2
(Rc61, mirror finish), 1 drop of oil, room temperature, sliding speed 5mm / s, 200mm stroke, load 1kgf
The friction coefficient after 100 reciprocating motions was measured under the above conditions.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

[Table 3]

[0023]

[Table 4]

From Table 1, the incorporation of the water-repellent silica colloid imparts a high degree of seizure resistance and abrasion resistance (see Examples 1 to 5 and Comparative Examples 1 to 7), as well as corrosion of the friction surface and It can be seen that the degree of life reduction due to the oxidation of the lubricant is suppressed as compared with the conventional extreme pressure agents and oiliness agents (see Example 3 and Comparative Examples 8 to 10). Also, when other additives are blended with the water-repellent silica colloid, good corrosion and suppression of reduction in the life of the lubricant are recognized (see Examples 6 to 9 and Comparative examples 8 to 11).

[0025]

As described above, according to the present invention, it is possible to obtain a lubricant which is excellent in seizure resistance and wear resistance, and which is less likely to cause a reduction in life due to corrosion of the friction surface and oxidation of the lubricant. Therefore, the lubricant of the present invention is effectively used as a general-purpose lubricant in various applications such as bearing oil, sliding surface oil, hydraulic fluid, machine tool oil, and shock absorber oil.

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Claims (3)

[Claims] 1. A lubricant comprising a base oil containing a water-repellent silica colloid. 2. Base oil, based on the total weight of the lubricant.
2. The lubricant according to claim 1, which contains 9999 to 90% by weight and 0.0001 to 10% by weight of a water-repellent silica colloid as a silica content. 3. The water-repellent silica colloid is a silica colloid silylated with a higher alkyl-substituted silane having 12 or more carbon atoms, and has a hydrophobicity of 50% or more and a colloidal particle diameter of 100 nm or less. Or the lubricant according to 2.