JP3356194B2 - Grease composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grease composition applied to various bearings, and more particularly to a grease suitable for improving bearing acoustic characteristics at high temperatures and extending the acoustic characteristics from high speed to low speed rotation. Composition.

2. Description of the Related Art In recent years, air conditioners (air conditioners) have become more sophisticated and multifunctional, and for example, room temperature has been reduced in a short time by rapid cooling by high-speed operation. After that, a constant temperature is maintained by low-speed operation. At the time of low-speed operation, low-noise operation in which air blowing noise, motor rotation noise, and the like are suppressed is required. However, during low-speed operation, the cooling efficiency inside the device decreases, and the temperature of the bearing incorporated in the motor may rise to around 100 to 120 ° C. As a result, the grease composition applied to the bearing deteriorates, causing noise.

Conventionally, ester grease compositions using lithium soap as a thickener and dioctyl sebacate (DOS) or pentaerythritol (PET) as a base oil have been used as grease compositions for bearings in air conditioners. ing. This grease composition has a problem that the dispersibility of lithium soap is good and the acoustic characteristics are excellent, but the acoustic characteristics at a high temperature deteriorate early. Japanese Patent Application Laid-Open No. 4-252296 discloses that a lithium complex grease composition to which polyoxyethylene ether is added improves the acoustic characteristics by increasing the dropping point and increasing the dispersibility of a base oil and a thickener. Propose that. However, although the grease composition shows superiority in the initial acoustic characteristics, no knowledge about the acoustic characteristics at high temperatures has been obtained.

Accordingly, the present invention provides a grease composition which solves the above-mentioned problems of the prior art, improves the acoustic characteristics of the bearing at high temperatures, and extends the life of the acoustic characteristics at high speed to low speed rotation. The purpose is to:

[0004]

The object of the present invention is to provide a grease composition according to the present invention, comprising (1) a base oil and a thickener, wherein the thickener is lithium stearate.
The base oil is an ester oil having a kinematic viscosity at 40 ° C. of 80 to 300 mm ² / sec and a thickener content of 5% by weight, comprising 15 to 60% by weight and 40 to 85% by weight of lithium 12-hydroxystearate. (2) The grease composition according to the above (1), wherein the ester oil is at least one of a hindered ester oil and an aromatic ester oil. Is achieved by

Hereinafter, the grease composition according to the present invention will be described in detail. The base oil used in the grease composition of the present invention is an ester oil. The ester oil is not particularly limited, but is a diester oil obtained from a reaction between a dibasic acid and a branched alcohol, an aromatic ester oil obtained from a reaction between an aromatic tribasic acid and a branched alcohol, and a polyhydric alcohol and a monobasic oil. Hindered ester oils obtained from acid reactions are preferably used. Considering heat resistance (use conditions under high temperature and high speed), it is selected from aromatic ester oils and hindered ester oils, and it is particularly preferable to use them alone or as a mixture. As diester oil, dioctyl adipate (D
OA), diisobutyl adipate (DIBA), dibutyl adipate (DBA), dioctyl azelate (DO
Z), dibutyl sebacate (DBS), dioctyl sebacate (DOS), methyl acetyl ricinoleate (M
AR-N) and the like. Examples of the aromatic ester oil include trioctyl trimellitate (TOTM), tridecyl trimellitate, and tetraoctyl pyromellitate.

Examples of the hindered ester oil include those obtained by appropriately reacting a polyhydric alcohol shown below with a monobasic acid. The monobasic acid reacted with the polyhydric alcohol may be used alone or in combination. Further, it may be used as a complex ester which is an oligoester of a polyhydric alcohol and a mixed fatty acid of a dibasic acid / monobasic acid. Examples of the polyhydric alcohol include trimethylolpropane (TMP), pentaerythritol (PE), dipentaerythritol (DPE), neopentyl prechol (NPG), 2-methyl-2-propyl-1,3-propanediol (MPPD). ) And the like. The monobasic acids, mainly monovalent fatty acids from C ₄ C ₁₈ are used. Specifically, for example, butyric acid, valeric acid, caproic acid, caprylic acid, enanthic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, mystyric acid, palmitic acid, tallow fatty acid, sularic acid, caproleic acid, undecylenic acid, Lindelic acid, tuzunic acid, physeteric acid, myristolic acid, palmitoleic acid, petroselinic acid,
Oleic acid, elaidic acid, asclepic acid, vaccenic acid, sorbic acid, linoleic acid, linolenic acid, savininic acid, ricinoleic acid and the like.

Base oil viscosity: 40 ° C. Kinematic viscosity: 80-300 mm
In the range of ² / sec, but especially 80～250Mm ² / sec is preferred. If the kinematic viscosity is less than 80 mm ² / sec, the film-forming property is not sufficient especially at low speed rotation, and if the viscosity is 300 mm ² / sec or more, the motor is overloaded and the bearing torque is undesirably increased.

[0008] Thickeners used in the grease composition of the present invention include lithium stearate (hereinafter referred to as lithium soap A), and lithium lithium 12-hydroxystearate.
Beam (hereinafter, referred to as a lithium soap B) from the constructed. The lithium soap B has a high affinity for the base oil due to the action of the hydroxyl group contained in the structure, has a good dispersibility, and can improve the acoustic characteristics of the bearing to which the grease composition is applied. In addition, by using lithium soap A having no hydroxyl group in the structure, the soap structure is more stable, a dense soap structure is obtained, and the durability of the present invention under high-temperature conditions is improved. The thickener is contained in the grease composition in an amount of 5 wt% or more and less than 20 wt%, preferably 5 to 18 wt%.
wt%. If the thickener is less than 5 wt%, the consistency increases, the grease softens, and the grease leaks out of the bearing, failing to obtain sufficient acoustic characteristics. 20wt
% Or more, the torque and the acoustic characteristics at high temperatures are inferior.

The grease composition of the present invention contains the above-mentioned base oil and a thickener, but as long as the preferable properties are not impaired, in addition to the base oil and the thickener, a rust inhibitor, an antioxidant, etc. Can be contained. For example, other thickeners such as metal soaps made of metal salts other than lithium, benton and silica gel; amine-based, phenol-based, sulfur-based,
Antioxidants such as zinc dithiophosphate; chlorine-based, sulfur-based,
Extreme pressure agents such as phosphorus, zinc dithiophosphate, and organic molybdenum; oily agents such as fatty acids and vegetable oils; rust inhibitors such as petroleum sulfonate, dinonylnaphthalene sulfonate, sorbitan esters; Agent; polymethacrylate, polyisobutylene,
Viscosity index improvers such as polystyrene and the like can be added alone or in combination of two or more.

[0010]

EXAMPLES The present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples. [Examples 1 to 7 , Comparative Examples 1 to 20] Grease compositions were prepared by mixing thickeners and base oils as shown in Tables 1 to 4 . The total amount of lithium stearate, lithium 12-OH stearate and base oil was 950 g,
To this, an antioxidant, a rust inhibitor, and a metal deactivator were added in a total amount of 50 g to obtain a grease composition having a total amount of 1000 g.
In addition, the thickener amount (wt%) and base oil viscosity (40 ° C.) of each grease composition are also shown in the same table.

[0011]

[Table 1]

[0012]

[Table 2]

[0013]

[Table 3]

[0014]

[Table 4]

Each grease composition is applied to a test bearing,
(1) Bearing acoustic test and (2) rotational torque test.

(1) Bearing acoustic test As a test bearing, rotary washing was performed twice with petroleum benzene,
Using a ball bearing with a plastic retainer having an inner diameter of 6 mm, an outer diameter of 15 mm, and a width of 5 mm, which was dried at room temperature and completely degreased, 0.050 g of each grease composition was sealed in this test bearing using a syringe, and non-contact. Sealed with a rubber seal.
Sixteen bearings were prepared for each grease composition and mounted on a grease life tester shown in FIGS. This grease life tester uses a rubber bearing 2 and a pulley 3 to connect a test bearing placed in a housing 1 to a motor 4.
It is rotated by the power of. Then, the grease life tester was housed in a thermostat adjusted to 120 ° C., and the inner ring was rotated at 300 rpm and 5600 rpm (both with an axial load of 2 kgf) for 1000 hours. 10
After 00 hours, the bearing was taken out, and the acoustic characteristics of the bearing were examined according to the following evaluation criteria.

The acoustic measurement of the bearing is performed using an Anderon meter, and the acoustic characteristic is determined by comparing the Anderon value of the bearing immediately after the grease composition is sealed and the Anderon value of the bearing after 1000 hours of rotation. Was. The results of the determination are shown in Tables 1 to 4 above, as "O" without a decrease in acoustic characteristics, "A" with a slight decrease and "X" with a decrease. It can be seen that the grease compositions (Examples 1 to 7 ) according to the present invention have excellent acoustic characteristics both at low speed rotation and at high speed rotation. On the other hand, Comparative Examples 1 to 19 tend to be inferior in acoustic characteristics especially at the time of low-speed rotation. In Comparative Example 20, no acoustic measurement was performed due to an initial acoustic defect.

(2) Rotational torque test Rotational washing was performed twice with petroleum benzene as a test bearing.
Using a ball bearing with a plastic retainer having an inner diameter of 5 mm, an outer diameter of 13 mm, and a width of 4 mm, which was dried at room temperature and completely degreased, 0.016 g of each grease composition was sealed in this test bearing using a syringe, and was not contacted. Sealed with a rubber seal.
Rotational torque tests were performed on the bearings for each grease composition for 5 times.
Prepare them individually and attach them to the torque measuring device shown in FIG.
With the preload of 2 kgf applied, the inner ring of the bearing 10 is
After a rotation of 00, the torque value measured using the strain gauge 11 was recorded on a recorder, and the value was determined when the torque after 10 minutes of the rotation was substantially stable. In FIG. 3, 1
2 is an air spindle, 13 is an arbor, 14 is an aluminum cap, and 15 is an air bearing.

The results of the determination are also shown in Tables 1 to 4 . In the table, if the measured value is 3 kgf · cm or less, “○”, 3 kgf
・ Those exceeding cm were marked “×”. All the grease compositions (Examples 1 to 7 ) according to the present invention have a small rotational torque, and are found to be practically preferable. Also, from the comparative example,
It was confirmed that when the base oil viscosity was out of the range of the present invention, the rotational torque increased.

[0020]

As described above, the grease composition of the present invention has a kinematic viscosity at 40 ° C. of 80 to 300 mm ² / s.
base oil consisting of ec and ester oil, and lithium stearate
And a thickener composed of 12-hydroxystearic acid to improve the bearing acoustic characteristics at high temperatures and prolong the life of acoustic characteristics from high to low speed rotation. it can.

[Brief description of the drawings]

FIG. 1 is a schematic view of an apparatus used for a bearing acoustic test.

FIG. 2 is a sectional view of a main part for describing a rotation mechanism of the apparatus of FIG.

FIG. 3 is a schematic view of an apparatus used for a rotational torque test.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Housing 2 Rubber belt 3 Pulley 4 Motor 10 Bearing 11 Strain gauge 12 Air spindle 13 Arbor 14 Aluminum cap 15 Air bearing

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI C10N 10:02 C10N 20:02 20:02 30:00 Z 30:00 30:08 30:08 40:02 40:02 50: 10 50:10 (72) Inventor Michiharu Naka 1-5-50 Kugenuma Shinmei, Fujisawa-shi, Kanagawa Nippon Seiko Co., Ltd. (56) References JP-A-1-170692 (JP, A) JP-A-1- 308496 (JP, A) JP-A-51-95569 (JP, A) JP-A-54-32509 (JP, A) JP-A-6-330070 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C10M 169/02 C10M 105/18 C10M 105/32-105/48 C10M 117/02-117/04 C10N 10:02 C10N 20:02 C10N 30:00 C10N 30:08 C10N 40:02 C10N 50:10

Claims (2)

(57) [Claims] 1. A grease composition comprising a base oil and a thickener, wherein the thickener comprises a lithium stearate 15 to 60 wt% and 12-hydroxystearic acid and lithium 40～85Wt%, The base oil is 40
℃ kinematic viscosity of the ester oil 80~300mm ² / sec,
A grease composition wherein the content of the thickener is 5 wt% or more and less than 20 wt%. 2. The grease composition according to claim 1, wherein the ester oil is at least one of a hindered ester oil and an aromatic ester oil.