JPH06228583A - Lubricant composition for bearing - Google Patents

Abstract

(57) [Summary] [Object] The present invention provides a bearing lubricating composition having excellent mechanical strength, which enables stable bearing sliding even under extremely harsh operating conditions in which a large load is applied. It can contribute to the dynamic characteristics. [Composition] Lithium soap-mineral oil-based lubricating grease 5 to 96% by weight, average molecular weight 1 × 10 ^{6 to} 5 × 10 ⁶
Of 9 to 1% by weight of ultra-high molecular weight polyolefin powder and 3 to 30% by weight of a fibrous filler such as glass fiber, carbon fiber, aramid fiber, potassium titanate fiber, and the like to gelate the ultra-high molecular weight polyolefin. The lubricant composition for bearings is dispersed and held at a temperature not lower than the point and not higher than the dropping point of the lubricating grease to obtain a solidified lubricating composition for bearing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solidified lubricating composition for bearings, and more specifically, various bearings for outdoor working machines, bearings for printing machines, bearings for twisting machines, bearings for automobile parts and the like. The present invention relates to a solidified lubricating composition for a bearing, which is filled in the bearing.

[0002]

2. Description of the Related Art Generally, it is well known that a bearing is filled with a lubricating composition such as grease in order to improve its slidability and durability. In the case where a strong inertial force is exerted by moving, for example, a twisting machine bearing or the like needs to be filled with a lubricating composition that is not biased inside the bearing or scattered outside the bearing. Further, in a bearing of a machine used outdoors, it is necessary to fill it with a lubricant composition having a characteristic that even if rainwater or the like does not flow out of the bearing.

As a bearing lubricant composition that withstands such use conditions, for example, as described in JP-A-54-132071, a composition obtained by blending ultra-high molecular weight polyethylene with a lubricating oil such as mineral oil. It is known that the bearing is filled with a liquid or semi-solid material, which is then heat-treated and then cooled to be solidified.

In such a lubricating composition, ultrahigh molecular weight polyethylene is superior in rigidity and oil retention in a gel state as compared with low molecular weight polyethylene (for example, average molecular weight 2 × 10 ³ to 1 × 10 ⁵ ). It was a non-fluid one that utilized the above properties.

[0005]

However, when the above conventional bearing lubricating composition is heated and solidified in the bearing, the lubricating oil such as mineral oil, which is a lubricating component, is thermally fused with an ultrahigh molecular weight. However, even if it is solidified, its mechanical strength is low.

Therefore, the present invention solves the above-mentioned problems and makes the lubricating composition for bearings excellent in mechanical strength and stable even under extremely harsh operating conditions under which a large load is applied. The challenge is to contribute to the sliding characteristics of the bearing.

[0007]

In order to solve the above problems, in the present invention, the lubricating grease is 5 to 96% by weight.
In addition, 92 to 1% by weight of an ultrahigh molecular weight polyolefin powder having an average molecular weight of 1 × 10 ^{6 to} 5 × 10 ⁶ and 3 to 30% by weight of a fibrous filler are added to the gel point of the ultrahigh molecular weight polyolefin. The bearing lubricating composition is solidified by being dispersed and held at a temperature not lower than the dropping point of the lubricating grease.

The details will be described below.

The ultrahigh molecular weight polyolefin powder used in the present invention may be a powder made of polyethylene, polypropylene, polybutene or a copolymer thereof, or a mixed powder prepared by mixing individual powders, and each powder has a molecular weight of 1 × average molecular weight measured by viscosity method
10 ^{6 to} 5 × 10 ⁶ . Polyolefins having such an average molecular weight range are superior to low molecular weight polyolefins in rigidity and oil retention, and hardly flow even when heated to a high temperature. The blending ratio of such ultra-high molecular weight polyolefin in the lubricating composition is 92-
1% by weight, the amount of which changes the desired oil separation degree, tenacity and hardness of the composition. Therefore, as the amount of the ultra high molecular weight polyolefin increases, the hardness of the gel after the dispersion and holding at the predetermined temperature increases.

The lubricating grease used in the present invention is not particularly limited in the base oil and the thickening agent. For example, as a lubricating grease thickened with soap or non-soap, lithium soap-diester type, lithium soap-mineral oil type, Sodium soap-mineral oil type, aluminum soap-mineral oil type, lithium soap-diester mineral oil type, non-soap-diester type, non-soap-mineral oil type, non-soap-polyol ester type, lithium soap-polyol ester type grease, etc. You can

Further, the fibrous filler in the present invention is
It may be either inorganic or organic. Examples of the inorganic fibrous filler include glass fiber, carbon fiber,
Graphite fiber, metal fiber such as stainless steel, calcium silicate fiber, potassium titanate fiber, aluminum borate fiber, silicon carbide fiber, silicon nitride fiber, magnesium sulfate fiber, zinc oxide whisker, magnesia fiber,
Examples thereof include calcium sulfate fiber, magnesium borate fiber, titanium boride fiber, alumina fiber, tyranno fiber, zirconia fiber and zonolite fiber.

As the organic fibrous filler, aramid fiber, polyethylene fiber, polyester fiber, polyamide fiber (nylon fiber), tetrafluoroethylene fiber (Teflon fiber), polyvinyl alcohol fiber, phenol fiber, polyphenylene sulfide fiber. , Polyimide fiber, etc. can be exemplified.

The amount of such fibrous filler added is 3 to.
It is 30% by weight. This is because if the amount is less than 3%, the composition has no reinforcing effect, and if the amount exceeds 30% by weight, the fusion of the polyolefin is hindered and the required reinforcing effect cannot be obtained.

The bearing lubricating composition of the present invention also comprises
Add an additive to suppress the seepage of oil on the surface,
It is desirable to further stabilize its lubricating properties. Such an additive moderately suppresses the oil separation rate of the oil leached on the oily surface of the lubricating composition, and is a composition such as a solid wax or a low-molecular-weight polyolefin containing the wax among waxes. It may be a thing. Examples of the solid wax include vegetable waxes such as carnauba wax and candelina wax, animal waxes such as beeswax and insect white wax, and petroleum waxes such as paraffin wax.

The blending ratio of the additive for suppressing such oil oozing is preferably 1 to 50% by weight in the composition. The reason is that the higher the blending ratio is, the slower the rate of oil seeping out to the surface can be. However, if it exceeds 50% by weight, the mechanical strength of the bearing lubricating composition is lowered, which is not preferable. .

In order to disperse and retain the ultra-high molecular weight polyolefin, the fibrous filler and the oil exudation inhibitor in the above-mentioned lubricating grease, after mixing the above-mentioned materials, the temperature above the temperature at which the ultra-high molecular weight polyolefin causes gelation is exceeded. , For example 1
It is heated to about 50 to 200 ° C., then cooled and solidified to obtain a lubricating composition having an oily surface, that is, a surface from which oil oozes out.

[0017]

The lubricating composition for a bearing according to the present invention contains an ultra high molecular weight polyolefin and is in a solid state, and a predetermined amount of a fibrous filler compensates for a decrease in self-bonding force of the ultra high molecular weight polyolefin due to the lubricating oil. The mechanical strength is further increased. Therefore, even under extremely severe operating conditions such as mechanical load and large inertial force, there is no deviation inside the bearing or scattering outside the bearing,
Delivers stable lubricity.

[0018]

EXAMPLES The raw materials used in Examples and Comparative Examples are collectively shown below. In addition, the abbreviations are shown in [], and the mixing ratios are all weight%.

(1) Ultra High Molecular Weight Polyolefin [Polyolefin] Mitsui Petrochemical Co., Ltd .: Miperon, Particle Size 30 μm (2) Solid Wax Containing Low Molecular Weight Polyolefin [Solid Wax] Mitsui Kasei: Sun Wax (3) Lubrication Grease Lithium soap-mineral oil grease (4) Glass fiber Asahi Fiber Glass Co., Ltd .: Milled fiber MF-K
AC (5) Carbon fiber Toray: Milled fiber MLD30 (6) Aramid fiber Teijin: Conex cut fiber (7) Potassium titanate fiber Otsuka Chemical: Tismo D101 [Examples 1 to 4] Ultra high molecular weight Polyolefin, solid wax containing low molecular weight polyolefin, and lubricating grease as main components, and fibrous fillers were mixed in the mixing ratio shown in Table 1, and this mixture was heated in a thermostat at 160 to 180 ° C. for 30 minutes. And solidified.

With respect to the obtained solid lubricating composition,
The hardness (a), the load (b) the fracture load, and the bearing torque (c) were examined by the following test methods, and the results are also shown in Table 1.

(A) Hardness Hs (Shore hardness) according to JIS K6301 5.2
Was measured.

(B) Load Breaking Load The bearing lubricating composition of the example was coated with an inner diameter of 30 mm and an outer diameter of 60 m.
It was molded into a ring shape having a width of 15 mm and a width of 15 mm, and was loaded at a loading speed of 3 mm / min using an autograph manufactured by Shimadzu Corporation, and the maximum load when the ring was broken was measured.

(C) Bearing Rotational Torque The mixture before heating of the example was enclosed in a bearing 6204, rubber non-contact seals were attached to both sides of the bearing, and this was attached to a torque tester to provide a radial load of 4 kgf and a rotation speed. 360
The rotation torque was measured under the conditions of 0 rpm and room temperature.

[0024]

[Table 1]

[Comparative Example 1] The raw materials were mixed in exactly the same manner as in Examples 1 to 4 except that the materials in Examples 1 to 4 to which no fibrous filler was not added were used. By heating in exactly the same manner, a solid lubricant composition for bearing was obtained. The tests of (a) to (c) described above were performed on Comparative Example 1, and the results are also shown in Table 1.

As is clear from the results of the physical properties shown in Table 1, in Examples 1 to 4 in which the fibrous filler was added and all other predetermined conditions were satisfied, the bearing rotation torque was not reduced, It was extremely excellent in Hs hardness and load breaking load.

On the other hand, in Comparative Example 1 in which the fibrous filler was not added, the load breaking load was 26-
It turned out to be as low as 30%.

[0028]

As described above, according to the present invention, a lubricating grease, a super-high molecular weight polyolefin having a predetermined average molecular weight, and a fibrous filler are blended in predetermined amounts, respectively. Has the advantage of being a lubricating composition for a bearing, which has excellent mechanical strength and can contribute to the sliding characteristics of the bearing in a stable manner even under extremely severe operating conditions in which a large load is applied.

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Claims (1)

[Claims] 1. Lubricating grease 5 to 96% by weight, ultrahigh molecular weight polyolefin powder having an average molecular weight of 1 × 10 ^{6 to} 5 × 10 ⁶ 92 to 1% by weight, and fibrous fillers 3 to 3
0% by weight is dispersed and held at a temperature not lower than the gel point of the ultra-high molecular weight polyolefin and not higher than the dropping point of the lubricating grease to solidify the bearing lubricating composition.