JP3433402B2 - Oil composition for impregnated bearings - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil composition for impregnated bearings, and more specifically, it can reduce friction coefficient and prevent wear in a sintered alloy bearing portion and has excellent compatibility with various bearing materials. The present invention relates to an oil composition for impregnated bearings.

[0002]

2. Description of the Related Art Sintered alloy bearings use iron, copper, tin, lead, zinc, carbon, and other metal powders as raw materials and sinter-mold them to impregnate lubricating oil with a porous substance. It is a thing. This sintered material can be roughly divided into copper-based and iron-based materials. Copper-based materials such as acoustics and home appliances (VTRs, car stereos, fans, etc.), and iron-based materials include automobile electrical components (fan motors, etc.). ) Etc., but the quality is impregnated with lubricating oil (sintered alloy bearing oil)
Is dominated by the performance of. That is, such a sintered alloy bearing oil is required to have excellent heat resistance and oxidation stability at high temperatures and low evaporativeness due to heat generation in the rotating part. Sex is required. In addition, lubricity at high and low temperatures and compatibility with sintered materials and plastic materials used in the periphery thereof are also required. In addition, in recent years, as sintered alloy bearings have become smaller and thinner and the operating environment has become more severe and diverse, further improvement in wear resistance, seizure resistance and oxidation stability has been achieved in sintered alloy bearing oils. There is an urgent need. In addition, a sintered alloy bearing oil used for a capstan bearing or a motor bearing of a portable radio cassette player, a portable CD player, a portable MD player is required to have a reduced friction coefficient from the viewpoint of power consumption. As such a bearing oil, for example, Japanese Patent Application Laid-Open No. 7-53984 describes a base oil to which a specific metal-containing additive or the like is added. It was not possible to satisfy all the required properties of oil, such as wear resistance, oxidation stability and low friction coefficient.

[0003]

The present invention has been made under such circumstances. That is, it is an object of the present invention to provide an oil composition for impregnated bearings which, in a sintered alloy bearing, reduces its friction coefficient and improves wear resistance and bearing material compatibility.

[0004]

As a result of intensive studies to achieve the above object, the inventors of the present invention have reduced the friction coefficient in a sintered alloy bearing by adding a specific phosphorus compound to the base oil. It has also been found that its wear resistance and bearing material compatibility can be improved. That is,
The present invention provides an oil composition for impregnated bearings, characterized in that the base oil is blended with at least one selected from dihydrocarbyl hydrogen phosphite and trihydrocarbyl phosphate having a hydrocarbyl group having 12 to 30 carbon atoms. It is provided.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below. As the base oil of the oil composition for impregnated bearings of the present invention, those composed of mineral oil and / or synthetic oil can be used,
Further, a mixture of these with a viscosity index improver can also be used. The mineral oil and synthetic oil that can be used in the present invention are not particularly limited in kind and various properties, but those having a kinematic viscosity at 40 ° C. in the range of 5 to 500 mm ² / sec can be used. The kinematic viscosity is 5
When it is less than mm ² / sec, there are problems such as a decrease in oil film strength and increase in evaporation loss, and when it exceeds 500 mm ² / sec, viscous resistance increases, which may cause various troubles. For this reason, the above range is 10 to 3
It is preferably in the range of 00 mm ² / sec. Here, as the mineral oil, for example, solvent refining, hydrogenation refining, hydrocracking,
Examples thereof include paraffinic mineral oil obtained by a refining method such as dewaxing treatment, intermediate base mineral oil, naphthenic mineral oil, and the like, or those containing a viscosity index improver.

Examples of the synthetic oil include polybutene, polyolefin (including α-olefin copolymer), various esters (eg, polyol ester, dibasic acid ester, phosphoric acid ester, etc.), and various ethers (eg, polyester). Phenyl ether, etc.), alkylbenzene, alkylnaphthalene, etc., or a mixture of these with a viscosity index improver. In the present invention, two or more kinds of the above mineral oils can be used in combination as the base oil, and two or more kinds of the above mineral oils can also be used in combination as the synthetic oil. Further, each of the above mineral oil and synthetic oil may be used in combination.

As the above-mentioned base oil, those containing a poly-α-olefin, an ethylene-α-olefin copolymer or a hydride thereof are preferably used, and particularly, the poly-α-olefin has 6 to 14 carbon atoms. .Alpha.-olefin oligomers of
An ethylene-propylene copolymer is preferably used as the olefin copolymer. In particular, in the present invention,
As the base oil, (a) poly-α-olefin or hydride thereof, (b) ethylene-α-olefin copolymer or hydride thereof, and (c) (c-1) poly-α-olefin, ethylene- It is preferable to use at least one kind selected from the mixture of the α-olefin copolymer or a hydride thereof and (c-2) alkylbenzene or alkylnaphthalene from the viewpoint of low temperature characteristics and prevention of sludge generation. Further, a mixture of these with a viscosity index improver can also be used.

When the above base oil is used at a high temperature, "oil pressure escape" occurs due to the oil permeability of the bearing material, the oil film strength is reduced, and the amount of oil leaked from the bearing increases. There are no problems such as shortening the service life or fouling the surroundings, and there is no problem such as insufficient oil supply to the lubrication part due to reduced fluidity of the oil at low temperature startup. The alkylbenzene or alkylnaphthalene used as the base oil in the present invention has 6 carbon atoms in each of the benzene ring and the naphthalene ring.
Those having at least one alkyl substituent of ˜30, preferably 10 to 24 can be used. The content of the alkylbenzene or alkylnaphthalene in the base oil is preferably 3 to 90% by weight. Addition of alkylbenzene or alkylnaphthalene, particularly by containing 3% by weight or more of the base oil, has the effect of suppressing the decrease in oil pore distribution due to the generation of sludge. Further, if the above content exceeds 90% by weight, the aniline point decreases, the sealing material around the bearing swells and contracts,
The amount of oil leaking from the bearing may increase, and further, the viscosity index decreases, which may cause the above-mentioned problems during high temperature use or low temperature start. From the above-mentioned various points, the content of alkylbenzene or alkylnaphthalene is preferably 3 to 75% by weight, and more preferably 3 to 60% by weight of the base oil.

Preferred examples of the viscosity index improver that can be used in the above base oil include olefin (co) polymers such as ethylene-propylene copolymer, polymethacrylate, polyisobutylene, etc., from the viewpoint of low temperature characteristics. Polymethacrylate is particularly preferably used. Its molecular weight is 10 in terms of number average molecular weight from the viewpoint of shear stability.
000 to 1,000,000, more than 10,000 to 100,00
It is preferably 0, particularly 10000 to 50000.

The oil composition for impregnated bearings of the present invention comprises the above base oil and at least one selected from dihydrocarbyl hydrogen phosphite and trihydrocarbyl phosphate having a hydrocarbyl group having 12 to 30 carbon atoms. is there. As the dihydrocarbyl hydrogen phosphite used here, those represented by the following general formula (I) are preferably used. (R ¹ O) ₂ POH (I) In the general formula (I), each R ¹ has 1 carbon atom.
Preferable examples are 2 to 30 alkyl groups or alkenyl groups. When the number of carbon atoms of the hydrocarbyl group in the dihydrocarbyl hydrogen phosphite is less than 12, stability is poor and sludge is liable to be generated. In addition, those having a carbon number of more than 30 have little effect on lubricity with respect to the compounding amount, and are difficult to obtain. From such a point, the carbon number of the hydrocarbyl group is further 14 to
22 is preferable. Specific examples of the dihydrocarbyl hydrogen phosphite used in the present invention include dilauryl hydrogen phosphite, dipalmityl hydrogen phosphite, distearyl hydrogen phosphite, and dioleyl hydrogen phosphite. Can be mentioned.

Further, as the trihydrocarbyl phosphate used in the present invention, those represented by the following general formula (II) are preferably used. (R ² O) ₃ P═O (II) In the general formula (II), R ² is preferably an alkyl group or an alkenyl group, and for the same reason as in the case of the dihydrocarbyl hydrogen phosphite, Those having 12 to 30 carbon atoms, more preferably 14 to 22 carbon atoms are preferably used. Specific examples of the trihydrocarbyl phosphate used in the present invention include trilauryl phosphate, trimyristyl phosphate, tripalmityl phosphate, tristearyl phosphate, trioleyl phosphate and the like.

The oil composition for impregnated bearings of the present invention comprises at least one selected from the above dihydrocarbyl hydrogen phosphite and trihydrocarbyl phosphate.
It is preferably contained in an amount of 0.01 to 10% by weight. If the content is less than 0.01% by weight, the effect of the present invention is hardly observed, and if it exceeds 10% by weight, the effect of addition is saturated and sludge may be easily generated. For this reason, the above content is more preferably 0.1 to 5% by weight, and particularly preferably 0.1 to 3% by weight. Within the above range, in the present invention, two or more kinds of dihydrocarbyl hydrogen phosphite can be used in combination, and two or more kinds of trihydrocarbyl phosphate can be used in combination. It is also possible to use a combination of each of dihydrocarbyl hydrogen phosphite and trihydrocarbyl phosphate.

The oil composition for impregnated bearings of the present invention contains a viscosity index improver, a pour point depressant, an ashless dispersant, and a metal-based detergent, if necessary, as long as the object of the present invention is not impaired. , Antioxidants, oiliness agents, rust preventives, surfactants, defoamers, friction modifiers, etc. can be added depending on the application. The oil composition for impregnated bearings of the present invention is used as a sintered alloy bearing by impregnating various sintered metal materials. Such a sintered alloy bearing can be used for various bearings, for example, a capstan bearing or a motor bearing of a portable radio-cassette player, a portable CD player, a portable MD player or the like.

[0014]

EXAMPLES Next, the present invention will be described more specifically by way of examples, but the present invention is not limited to these examples. The performance of the impregnated bearing oil composition was evaluated according to the following method. (1) Shell wear test (Company) According to JPI-5S-32-90 of Japan Petroleum Institute, the diameter (mm) of the wear mark was measured under the following conditions. Rotation speed: 1200 rpm, load: 40 kgf Oil temperature: 50 ° C., temperature: 60 minutes (2) Pendulum test (manufactured by Japan Automotive Engineering Society) According to JASO M314-88, the friction coefficient was measured under the following conditions. Ball: SUJ2 (3/16 inch) Roller pin: SUJ2, Oil temperature: 25 ° C (3) Bearing material immersion test The bearing material below is immersed in each test oil at 120 ° C for 100 hours for immersion test, and then bearing material. The presence or absence of corrosion and the amount of sludge generated in the test oil were evaluated. Here, the amount of sludge generated was measured using a Millipore filter having a pore size of 0.8 μ. Bearing material: Iron, JIS B1581 SBF 2118
Equivalent product Copper type, JIS B1581 SBK 1218 equivalent product

Examples 1 to 4 and Comparative Examples 1 to 4 Using the base oils shown in Table 1, oil compositions for impregnated bearings were prepared at the blending ratios (% by weight) shown in Table 2, and their various performances were prepared. Was evaluated. The results are shown in Table 2.

[0016]

[Table 1]

1) Poly-α-olefin: Kinematic viscosity (10
0 ° C.) 6 cSt (decene oligomer manufactured by Ethyl) 2) Poly-α-olefin: kinematic viscosity (100 ° C.) 10 c
St (decene oligomer manufactured by Ethyl Co.) 3) Poly-α-olefin: kinematic viscosity (100 ° C) 40c
St (decene oligomer manufactured by Ethyl Co.) 4) Alkylbenzene: Kinematic viscosity (40 ° C.) 50 cSt
(Branched heavy alkylbenzene having 1 to 2 C ₁₂ alkyl groups) 5) Alkylnaphthalene: kinematic viscosity (40 ° C.) 28 cSt
(Alkylnaphthalene having a C ₁₆ or C ₁₈ alkyl group)

[0018]

[Table 2]

[0019]

[Table 3]

[0020]

INDUSTRIAL APPLICABILITY The oil composition for impregnated bearings of the present invention is impregnated into various sintered metal materials to form a sintered alloy bearing, which lowers the friction coefficient and improves wear resistance and bearing material compatibility. be able to.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI C10M 107: 02 C10M 137: 02 137: 02 137: 04 137: 04) C10N 30:06 C10N 30:06 30:12 30:12 40:02 40:02 (58) Fields investigated (Int.Cl. ⁷ , DB name) C10M 137/02-137/04 C10M 105/06 C10M 107/02-107/18 C10M 169/04 C10N 30:06 C10N 30:12 C10N 40:02

Claims (6)

(57) [Claims] 1. An oil composition for impregnated bearings, which comprises a base oil blended with at least one selected from dihydrocarbyl hydrogen phosphite and trihydrocarbyl phosphate having a hydrocarbyl group having 12 to 30 carbon atoms. . 2. The oil composition for impregnated bearings according to claim 1, wherein the dihydrocarbyl hydrogen phosphite is a compound represented by the following general formula (I). (R ¹ O) ₂ POH (I) (wherein each R ¹ represents an alkyl group or an alkenyl group having 12 to 30 carbon atoms) 3. The oil composition for impregnated bearings according to claim 1, wherein the trihydrocarbyl phosphate is a compound represented by the following general formula (II). (R ² O) ₃ P═O (II) (In the formula, R ² represents an alkyl group or an alkenyl group) 4. The oil composition for impregnated bearings according to claim 1, containing 0.01 to 10% by weight of at least one selected from dihydrocarbyl hydrogen phosphite and trihydrocarbyl phosphate. 5. The base oil comprises (a) poly-α-olefin or hydride thereof, (b) ethylene-α-olefin copolymer or hydride thereof, and (c) (c-1) poly α-. The impregnated bearing according to any one of claims 1 to 4, comprising at least one selected from a mixture of olefin, ethylene-α-olefin copolymer or a hydride thereof, and (c-2) alkylbenzene or alkylnaphthalene. Oil composition. 6. The impregnated bearing is a sintered alloy bearing.
The oil composition for impregnated bearings according to any one of 1 to 5.