U.S. patent application number 09/997817 was filed with the patent office on 2002-08-08 for lubricant composition and bearing.
Invention is credited to Hirata, Masakazu, Mikami, Hidenobu, Mizutani, Toshiyuki.
Application Number | 20020107150 09/997817 |
Document ID | / |
Family ID | 18843572 |
Filed Date | 2002-08-08 |
United States Patent
Application |
20020107150 |
Kind Code |
A1 |
Mikami, Hidenobu ; et
al. |
August 8, 2002 |
Lubricant composition and bearing
Abstract
There are provided a lubricant composition for use in a
ball-and-roller bearing with a smaller diameter, and a
ball-and-roller bearing with a smaller diameter. The lubricant
composition comprises a base oil comprising a non-ester oil
containing a synthesized hydrocarbon oil, and a thickener
comprising a urea compound; wherein the urea compound is
represented by the formula (I): R.sub.1--(NHCONH--R.sub.2)n (I)
where R.sub.1 is a group containing an aromatic hydrocarbon,
R.sub.2 is at least one hydrocarbon group selected from the group
consisting of an alicyclic hydrocarbon group having 6 to 12 carbon
atoms and an aliphatic hydrocarbon group having 6 to 20 carbon
atoms, and n is 2 or 3; wherein the synthesized hydrocarbon oil has
kinetic viscosity of 20 mm.sup.2/s or more and less than 80
mm.sup.2/s at 40.degree. C.; and wherein the base oil comprises 50%
by weight or more of the synthesized hydrocarbon oil based on the
total weight of the base oil.
Inventors: |
Mikami, Hidenobu; (Kuwana,
JP) ; Mizutani, Toshiyuki; (Kuwana, JP) ;
Hirata, Masakazu; (Kuwana, JP) |
Correspondence
Address: |
James V. Costigan, Esq.
HEDMAN & COSTIGAN, P.C.
Suite 2003
1185 Avenue of the Americas
New York
NY
10036-2646
US
|
Family ID: |
18843572 |
Appl. No.: |
09/997817 |
Filed: |
November 30, 2001 |
Current U.S.
Class: |
508/100 ;
508/552 |
Current CPC
Class: |
C10M 2203/10 20130101;
C10M 2207/0406 20130101; C10M 2215/0813 20130101; C10M 2217/044
20130101; C10M 2229/053 20130101; C10N 2040/17 20200501; C10M
2215/06 20130101; C10M 2209/1033 20130101; C10M 2215/026 20130101;
C10M 2215/064 20130101; C10N 2040/18 20130101; C10M 105/06
20130101; C10M 2209/1055 20130101; C10M 107/50 20130101; C10M
119/24 20130101; C10M 2209/1095 20130101; C10M 2229/042 20130101;
C10M 2229/0465 20130101; C10M 2229/0535 20130101; C10M 2229/02
20130101; C10M 2229/0445 20130101; C10M 2229/048 20130101; C10M
2229/0415 20130101; C10M 2229/0515 20130101; C10M 2215/1013
20130101; C10M 2229/0455 20130101; C10N 2040/185 20200501; C10M
2209/103 20130101; C10M 2209/1085 20130101; C10M 2229/0435
20130101; F16C 33/6633 20130101; C10M 133/12 20130101; C10M
2215/121 20130101; C10M 2229/0425 20130101; C10M 2207/04 20130101;
C10M 2215/102 20130101; C10M 2229/0545 20130101; C10M 155/02
20130101; C10M 2203/065 20130101; C10M 2215/065 20130101; C10M
2205/02 20130101; C10M 2229/044 20130101; C10M 2229/0525 20130101;
C10M 107/02 20130101; C10M 2203/06 20130101; C10M 2207/046
20130101; C10M 2229/043 20130101; C10M 2229/05 20130101; C10N
2040/16 20130101; C10M 2217/045 20130101; C10M 127/06 20130101;
C10M 2215/067 20130101; C10M 2215/1026 20130101; C10N 2020/01
20200501; C10M 2229/051 20130101; C10M 145/26 20130101; C10M
2203/102 20130101; C10M 2215/006 20130101; C10N 2040/175 20200501;
C10M 2209/1075 20130101; C10M 2229/0475 20130101; C10M 169/00
20130101; C10M 2215/066 20130101; C10M 2229/052 20130101; C10M
2209/1045 20130101; C10M 2229/0485 20130101; C10M 105/18 20130101;
C10M 2229/04 20130101; C10M 129/16 20130101; C10M 2209/1065
20130101; C10M 2215/2275 20130101; C10M 2229/0505 20130101; C10M
107/34 20130101; C10M 2205/0206 20130101; C10M 2229/0405 20130101;
C10M 2229/041 20130101; C10N 2040/14 20130101; C10M 2215/2206
20130101; C10M 2229/054 20130101; C10M 2229/046 20130101; C10M
2229/047 20130101; C10M 115/08 20130101; C10M 2215/068 20130101;
C10M 2229/045 20130101; C10M 2229/025 20130101 |
Class at
Publication: |
508/100 ;
508/552 |
International
Class: |
C10M 169/02; C10M
133/20 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 8, 2000 |
JP |
P2000-374371 |
Claims
What is claimed is:
1. A lubricant composition, comprising: a base oil comprising a
non-ester oil containing a synthesized hydrocarbon oil, and a
thickener comprising a urea compound; wherein the urea compound is
represented by the formula (I): R.sub.1--(NHCONH--R.sub.2).sub.n
(I)where R.sub.1 is a group containing an aromatic hydrocarbon,
R.sub.2 is at least one hydrocarbon group selected from the group
consisting of an alicyclic hydrocarbon group having 6 to 12 carbon
atoms and an aliphatic hydrocarbon group having 6 to 20 carbon
atoms, and n is 2 or 3; wherein the synthesized hydrocarbon oil has
kinetic viscosity of 20 mm.sup.2/s or more and less than 80
mm.sup.2/s at 40.degree. C.; and wherein the base oil comprises 50%
by weight or more of the synthesized hydrocarbon oil based on the
total weight of the base oil.
2. The lubricant composition as claimed in claim 1, wherein the
synthesized hydrocarbon oil is at least one selected from the group
consisting of an aliphatic hydrocarbon oil and an aromatic
hydrocarbon oil.
3. The lubricant composition as claimed in claim 1, wherein the
synthesized hydrocarbon oil is an aliphatic hydrocarbon oil.
4. The lubricant composition as claimed in claim 3, wherein the
aliphatic hydrocarbon oil is at least one selected from the group
consisting of poly-.alpha.-olefine oil and a copolymer of
.alpha.-olefine and olefine.
5. The lubricant composition as claimed in claim 1, wherein the
synthesized hydrocarbon oil is mixed with at least one hydrocarbon
oil selected from the group consisting of a mineral oil such as
naphthene, paraffin, liquid paraffin, and hydrodewaxed oil; a
polyglycol oil such as polyalkylene glycol; an ether oil such as
alkyldiphenyl ether, and polyphenyl ether; and a silicone oil such
as polydimethyl siloxane, and polyphenyl methyl siloxane.
6. The lubricant composition as claimed in claim 5, wherein the
synthesized hydrocarbon oil is the ether oil.
7. The lubricant composition as claimed in claim 1, wherein the
R.sub.1 has an aromatic single ring, an aromatic condensed ring, an
aromatic single ring combined with methylene, cyanuric ring or
isocyanuric ring, or an aromatic condensed ring combined with
methylene, cyanuric ring or isocyanuric ring.
8. The lubricant composition as claimed in claim 7, wherein the
R.sub.1 is a residual group in which an isocyanate group is
eliminated from diphenylmethanediisocyanate, tolyleneduisocyanate,
or a duisocyanate polymer.
9. The lubricant composition as claimed in claim 8, wherein the
R.sub.1 is diphenylmethanediisocyanate or tolylenediisocyanate.
10. The lubricant composition as claimed in claim 1, wherein the
urea compound is a reaction product of at least one disocyanate
selected from the group consisting of diphenylmethanediisocyanate
and tolylenedusocyanate, and at least one amine compound selected
from the group consisting of octylamine, cyclohexylamine, and
toluidine.
11. The lubricant composition as claimed in claim 1, having worked
penetration of 220 to 280.
12. A ball-and-roller bearing with a smaller diameter
prelubricating a lubricant composition, wherein the lubricant
composition comprises a base oil comprising a non-ester oil
containing a synthesized hydrocarbon oil, and a thickener
comprising a urea compound; wherein the urea compound is
represented by the formula (I): R.sub.1--(NHCONH--R.sub.2).sub.n
(I)where R.sub.1 is a group containing an aromatic hydrocarbon,
R.sub.2 is at least one hydrocarbon group selected from the group
consisting of an alicyclic hydrocarbon group having 6 to 12 carbon
atoms and an aliphatic hydrocarbon group having 6 to 20 carbon
atoms, and n is 2 or 3; wherein the synthesized hydrocarbon oil has
kinetic viscosity of 20 mm.sup.2/s or more and less than 80
mm.sup.2/s at 40.degree. C.; and wherein the base oil comprises 50%
by weight or more of the synthesized hydrocarbon oil based on the
total weight of the base oil.
13. The ball-and-roller bearing as claimed in claim 12, which is
noise resistant and fretting corrosion resistant.
14. The ball-and-roller bearing as claimed in claim 12, which is a
spindle bearing for use in an apparatus for recording and reading
information.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a lubricant composition,
and a bearing prelubricating the lubricant composition. More
particularly, the present invention relates to a lubricant
composition for a ball-and-roller bearing with a smaller diameter,
and the ball-and-roller bearing with a smaller diameter applicable
to an electronic information recording and reading apparatus such
as a hard disk drive (HDD) that is needed to rotate with low noise
for a long period of time.
[0003] 2. Discussion of Background
[0004] Ball-and-roller bearings are used in various types of
electronic information recording and reading apparatuses, i.e., a
magnetic recording and reading apparatus such as a hard disk drive
(HDD) and a video tape recorder (VTR), a printing apparatus such as
a laser beam printer (LBP), and an optical apparatus such as a
compact disk (CD), a CD-ROM, a digital video disk (DVD), and a
DVD-ROM. The ball-and-roller bearing is required to have low torque
and excellent acoustic properties in order to decrease electric
power consumption of such apparatuses, and to operate with low
noise.
[0005] Such ball-and-roller bearing has a small diameter and is
called as a miniature bearing. Conventionally, lubricating oil or
grease is used for lubricating the ball-and-roller bearing with a
small diameter.
[0006] Even though the lubricating oil or grease is applied to the
conventional ball-and-roller bearing, a noise is apt to be
produced. It is contemplated that the noise is produced because an
oily film is poorly formed on a rolling surface of the bearing. In
many cases, torque of the bearing is significantly changed when the
noise is produced.
[0007] Japanese Patent Publication No. 8-209176 discloses a grease
composition for improving acoustic properties of a bearing, and for
prolonging the acoustic properties at high to low rotating speeds.
The grease composition comprises not less than 5% by weight and
less than 20% by weight of a thickener including 40 to 100% by
weight of a lithium salt of a fatty acid having 12 to 24 carbon
atoms and having no hydroxyl group, and a base oil with kinetic
viscosity of 80 to 300 mm.sup.2/s at 40.degree. C. including at
least 10% by weight of an ester oil. Also disclosed is a grease
composition comprising a thickener including 5 to 30% by weight of
at least one of diurea and a polyurea, and a base oil including at
least 10% by weight of an ester oil.
[0008] Japanese Patent Publication No. 11-325086 discloses a
ball-and-roller bearing for a hard disk drive (HDD) prelubricating
a grease, which comprises a base oil comprising an aromatic ester,
or a mixture of an aromatic ester and a polyol ester, and a lithium
soap type thickener. Such grease discharges less gases, and
provides long-term acoustic properties.
[0009] The grease for the ball-and-roller bearing uses the lithium
soap in the thickener and the ester oil in the base oil as
described in Japanese Patent Publication No. 11-325086. While the
grease provides excellent acoustic properties, there is easily
induced wearing with minor moving, so-called "fretting corrosion"
when the bearing in which the grease is prelubricated, or the
apparatus in which the bearing is incorporated is moved or
transported. The fretting corrosion might increase the noise upon
rotating the bearing, which cannot keep silence, resulting in poor
reliability of the bearing.
[0010] Also, the ester oil is used in the base oil, it is therefore
difficult to prevent the fretting corrosion even if diurea or
polyurea as the thickener is used.
SUMMARY OF THE INVENTION
[0011] An object of the present invention is to provide a lubricant
composition prelubricating grease applicable to a bearing for use
in an information recording and reading apparatus, which provides
excellent acoustic properties and produces less fretting
corrosion.
[0012] Another object of the present invention is to provide a
bearing prelubricating the aforementioned lubricant
composition.
[0013] The lubricant composition of the present invention comprises
a base oil comprising a non-ester oil containing a synthesized
hydrocarbon oil, and a thickener comprising a urea compound;
[0014] wherein the urea compound is represented by the formula
(I):
R.sub.1--(NHCONH--R.sub.2).sub.n (I)
[0015] where R.sub.1 is a group containing an aromatic hydrocarbon,
R.sub.2 is at least one hydrocarbon group selected from the group
consisting of an alicyclic hydrocarbon group having 6 to 12 carbon
atoms and an aliphatic hydrocarbon group having 6 to 20 carbon
atoms, and n is 2 or 3;
[0016] wherein the synthesized hydrocarbon oil has kinetic
viscosity of 20 mm.sup.2/S or more and less than 80 mm.sup.2/s at
40.degree. C.; and
[0017] wherein the base oil comprises 50% by weight or more of the
synthesized hydrocarbon oil based on the total weight of the base
oil. The term "non-ester oil" herein means an oil containing no
ester oil.
[0018] The lubricant composition according to the present invention
has worked penetration of 220 to 280, measured in accordance with
Japanese Industrial Standard (JIS) K2220.
[0019] The bearing prelubricating the aforementioned lubricant
composition is noise resistant and fretting corrosion
resistant.
[0020] The bearing prelubricating the aforementioned lubricant
composition is a spindle bearing for use in an apparatus for
recording and reading information.
[0021] As described above, the bearing prelubricating the lubricant
composition that comprises the base ester oil and the lithium soap
type thickener can provide improved acoustic properties. However,
the acoustic properties decrease when a synthesized hydrocarbon oil
is used instead of the ester oil. On the other hand, the
synthesized hydrocarbon oil can prevent the fretting corrosion.
According to the present invention, the fretting corrosion can be
prevented while keeping excellent acoustic properties by using the
urea compound represented by the formula (I), even though the
synthesized hydrocarbon oil is used.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] A more complete appreciation of the invention and many of
the attendant advantages thereof will be readily obtained as the
same becomes better understood by reference to the following
detailed description when considered in connection with the
accompanying drawing, wherein:
[0023] FIG. 1 is a schematic cross-sectional view of a
ball-and-roller bearing with a smaller diameter.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] In the lubricant composition of the present invention, the
base oil comprises the non-ester oil containing the synthesized
hydrocarbon oil.
[0025] The synthesized hydrocarbon oil is a hydrocarbon compound
including carbon and hydrogen. Examples include aliphatic
hydrocarbon oils such as poly-.alpha.-olefine oil, a copolymer of
.alpha.-olefine and olefine, and polybutene; aromatic hydrocarbon
oils such as alkylbenzene, alkylnaphthene, polyphenyl, and
synthesized naphthene.
[0026] Suitable synthesized hydrocarbon oil for use in the present
invention is aliphatic hydrocarbon oils that can provides both
acoustic properties and fretting corrosion resistance, when the
urea compound is used as the thickener. Among them,
poly-.alpha.-olefine, and a copolymer of .alpha.-olefine and
olefine are preferable.
[0027] It is preferred that the synthesized hydrocarbon oil have
kinetic viscosity of 20 mm.sup.2/s or more and less than 80
mm.sup.2/s at 40.degree. C. If the kinetic viscosity of the
synthesized hydrocarbon oil is less than 20 mm.sup.2/s, the
resultant lubricant composition has poor heat resistance. On the
other hand, if the kinetic viscosity exceeds 80 mm.sup.2/S, torque
of the bearing increases. These tendencies depend on percentages of
the synthesized hydrocarbon oil contained in the base oil.
[0028] Oil used as the base oil by mixing it with the synthesized
hydrocarbon oil include a mineral oil such as naphthene, paraffin,
liquid paraffin, and hydrodewaxed oil; a polyglycol oil such as
polyalkylene glycol; an ether oil such as alkyldiphenyl ether, and
polyphenyl ether; and a silicone oil such as polydimethyl siloxane,
and polyphenyl methyl siloxane.
[0029] The base oil contains 50% by weight or more of the
synthesized hydrocarbon oil based on the total weight of the base
oil. The synthesized hydrocarbon oil alone may constitute the base
oil. When the base oil contains 50% by weight or more of the
synthesized hydrocarbon oil, the fretting corrosion can be
prevented.
[0030] The urea compound used as the thickener is represented by
the formula (I):
R.sub.1--(NHCONH--R.sub.2).sub.n (I)
[0031] where R.sub.1 is a group containing an aromatic hydrocarbon,
R.sub.2 is at least one hydrocarbon group selected from the group
consisting of an alicyclic hydrocarbon group having 6 to 12 carbon
atoms and an aliphatic hydrocarbon group having 6 to 20 carbon
atoms, and n is 2 or 3. The urea compound can prevent the fretting
corrosion, and improve acoustic properties.
[0032] In the formula (I), the R.sub.1 has an aromatic single ring,
an aromatic condensed ring, an aromatic single ring combined with
methylene, cyanuric ring or isocyanuric ring, or an aromatic
condensed ring combined with methylene, cyanuric ring or
isocyanuric ring. Examples include a residual group in which an
isocyanate group is eliminated from diphenylmethanediisocyanate,
tolylenediisocyanate, or a diisocyanate polymer including dimer and
trimer. When the R.sub.1 is a group containing aromatic
hydrocarbon, heat resistance of the lubricant composition can be
improved.
[0033] The R.sub.2 is an alicyclic hydrocarbon group having 6 to 12
carbon atoms, an aliphatic hydrocarbon group having 6 to 20 carbon
atoms, or a hydrocarbon group containing them. When the R.sub.2 has
carbon atoms less than the defined range, heat resistance of the
lubricant composition is decreased. On the other hand, when the
R.sub.2 has carbon atoms exceeding the defined range, the acoustic
properties are decreased.
[0034] In the formula (I), R.sub.1--(NHCONH--R.sub.2).sub.n, n is 2
to 3. In view of keeping thermal stability of the lubricant
composition, it is preferred that n is 2 or 3.
[0035] The urea compound can be prepared by reacting an isocyanate
compound with an amino compound. It is preferred that the
isocyanate compound have approximately equivalent amino group as
that of the amino compound in order to leave no reactive free
radicals.
[0036] In the preparation of the lubricant composition, the
isocyanate compound and the amino compound can be reacted in the
base oil. Alternatively, the urea compound synthesized in advance
can be mixed with the base oil. The former is the preferable
preparing method, since the stability of the lubricant composition
is easily kept.
[0037] The lubricant composition has worked penetration of 220 to
280. When the lubricant composition having worked penetration
within this range is included within the ball-and-roller bearing
with a smaller diameter, an oily film can be formed successfully on
a rolling surface. Also, the fretting corrosion can be
prevented.
[0038] Any known additives can be incorporated into the lubricant
composition for improving the properties as required. Examples
include an antioxidant including amines, phenolics, dithiozinc
phosphates, or compounds containing sulfur; an extreme pressure
agent including dithiozinc phosphate, organic molybdenum, or
compounds containing chlorine, sulfur, or phosphorus; a rust
preventive including petroleum sulfonates, dinonyl naphthalene
sulfonates, or sorbitan esters; a metal deactivator including
benzotriazole, or sodium nitrite; and a viscosity index improver
including polymethacrylate, polyisobutylene, or polystyrene. These
can be added alone or in combination.
[0039] FIG. 1 shows an example of the bearing according to the
present invention. It is a schematic cross-sectional view of the
ball-and-roller bearing with a smaller diameter.
[0040] The ball-and-roller bearing 1 comprises an inner ring 2
having a rolling surface on an outer surface, an outer ring 3
having a rolling surface on an inner surface and a plural rolling
elements 4. The inner ring 2 and the outer ring 3 are
concentrically disposed. Plural rolling elements 4 are disposed
between the rolling surface of the inner ring 2 and the outer ring
3. The ball-and-roller bearing 1 also comprises a holder and a
sealing member (both are not shown). The aforementioned lubricant
composition 5 is filled between the inner ring 2 and the outer ring
3.
[0041] According to the present invention, the lubricant
composition 5 prepared using the urea compound and the non-ester
oil containing the synthesized hydrocarbon oil is applied to the
bearing, thereby preventing the fretting corrosion that is likely
to be produced on the rolling surface of the bearing. As the
fretting corrosion is prevented, the noise of the rolling bearing
will not be increased. As a result, the bearing moves silently. The
bearing of the present invention can be used as a spindle bearing
for use in an apparatus for recording and reading information,
i.e., a magnetic recording and reading apparatus such as a hard
disk drive (HDD) and a video tape recorder (VTR), a printing
apparatus such as a laser beam printer (LBP), and an optical
apparatus such as a compact disk (CD), a CD-ROM, a digital video
disk (DVD), and a DVD-ROM.
[0042] Other features of this invention will become apparent in the
course of the following description of exemplary embodiments, which
are given for illustration of the invention and are not intended to
be limiting thereof.
EXAMPLES 1 TO 6
[0043] In each Example, the base oil, the thickener, and the
antioxidant shown in TABLE 1 were used. Diisocyanate dissolved by
heating in the base oil to prepare a mixture. The amine shown in
TABLE 1 dissolved by heating in the mixture to prepare another
mixture. Both the mixtures were mixed to prepare a gel. The amount
of the amine was two times that of the diisocyanate by a mole
ratio. The antioxidant was added to the gel. The gel was stirred,
and passed through a roll mil to prepare semi-solid state lubricant
grease as a lubricant composition. In TABLE 1, the content of each
material is described in % by weight based on 100% by weight of the
total composition.
[0044] In TABLE 1, worked penetration of the resultant lubricant
grease, and viscosity of the base oil used are shown. Also,
acoustic properties and fretting corrosion measured as described
below are shown in TABLE 1.
[0045] 1) Acoustic properties
[0046] The lubricant grease was applied to two 684 bearings, each
of which was a deep groove ball bearing having an inside diameter
of 4 mm, and an outer diameter of 9 mm. The 684 bearings were set
to a rotation axis which rotates by one spindle motor. The bearings
were rotated under the conditions that the bearing rotation speed
was 2000 rpm, atmosphere temperature was 100.degree. C., and an
axial load was 0.8 kgf. A value of noise (dBA) was measured every
100 hours in accordance with JIS B1548-1960.
[0047] When the value of noise was less than 42 dBA, the bearings
were rotated again under the same conditions, and the value of
noise was measured again after 100 hours. The measurement was
repeated until the value of noise reached to 42 dBA. A time to
reach to 42 dBA was recorded to determine acoustic properties. The
acoustic properties are evaluated as described below, and the
evaluation results are shown in TABLE 1.
[0048] good: It took 600 hours or more until the value of noise
reached to 42 dBA.
[0049] not good: It took not less than 300 hours to less than 600
hours until the value of noise reached to 42 dBA.
[0050] bad: It took less than 300 hours until the value of noise
reached to 42 dBA.
[0051] 2) Fretting corrosion
[0052] The lubricant grease was applied to inside of 51204 bearing,
which was a thrust ball bearing having an inside diameter of 20 mm,
and an outer diameter of 40 mm. The bearing was vibrated
continuously for 2 hours under the conditions that a frequency was
30 Hz, an oscillating angle was 12 degree, atmosphere was room
temperature, and an axial load was 2450 N. After the test, the
bearing was weighed to determine a weight decrease caused by
wearing. Fretting corrosion is evaluated as described below, and
the evaluation results are shown in TALBE 1. The lesser the weight
decrease is, the higher the fretting corrosion resistant of the
lubricant grease is.
[0053] good: The weight decrease caused by wearing was less than 2
mg.
[0054] not good: The weight decrease caused by wearing was not less
than 2 mg to less than 3 mg.
[0055] bad: The weight decrease caused by wearing was 3 mg or
more.
1 TABLE 1 Example Composition 1 2 3 4 5 6 Base oil Ether oil*1 --
-- 9 22 -- 8.4 Ester oil*2 -- -- -- -- -- -- Synthesized
hydrocarbon oil*3 85.5 86.5 77.5 63.5 83.5 75.1 Thickener Amine
Octylamine 3.8 6.6 6.6 6.1 9.6 9.6 Cyclohexylamine 2.9 -- -- -- --
-- p-toluidine -- -- -- -- -- -- Diisocyanate MDI*4 7.3 6.4 6.4 5.9
-- -- TDI*5 -- -- -- -- 6.4 6.4 12-hydroxy Li stearate -- -- -- --
-- -- Antioxidant*6 0.5 0.5 0.5 0.5 0.5 0.5 Properties Viscosity
(at 40.degree. C., mm.sup.2/s) of base oil 46 46 36 44 46 36 Worked
penetration (JIS K2220) 220 240 250 290 240 260 Acoustic properties
good good good good good good Fretting corrosion resistance good
good good good good good *1:Alkylated diphenyl ether oil
*2:Pentaerythritol ester oil *3:Po1y-.alpha.-olefine oil
*4:Diphenylmethenediisocyanate *5:Tolylenedlisocyanate *6:Alkylated
diphenylamine
Comparative Examples 1, 2 and 6
[0056] In each Comparative Example, the base oil, the thickener,
and the antioxidant shown in TABLE 2 were used. Diisocyanate
dissolved by heating in the base oil to prepare a mixture. The
amine shown in TABLE 2 dissolved by heating in the mixture to
prepare another mixture. Both the mixtures were mixed to prepare a
gel. The amount of the amine was two times that of the diisocyanate
by a mole ratio. The antioxidant was added to the gel. The gel was
stirred, and passed through a roll mil to prepare semi-solid state
lubricant grease as a lubricant composition. In TABLE 2, the
content of each material is described in % by weight based on 100%
by weight of the total composition.
[0057] In TABLE 2, worked penetration of the resultant lubricant
grease, and viscosity of the base oil used are shown. Also,
acoustic properties and fretting corrosion measured as the same
procedures in Example 1 are shown in TABLE 2.
Comparative Examples 3 to 5
[0058] In each Comparative Example, the base oil, the thickener,
and the antioxidant shown in TABLE 2 were used, and mixed by
heating them at a melting point of the thickener or more, dissolved
uniformly, and then cooled to prepare a gel. The gel was passed
through a roll mil to prepare semi-solid state lubricant grease as
a lubricant composition. In TABLE 2, the content of each material
is described in % by weight based on 100% by weight of the total
composition.
[0059] In TABLE 2, worked penetration of the resultant lubricant
grease, and viscosity of the base oil used are shown. Also,
acoustic properties and fretting corrosion measured as the same
procedures in Example 1 are shown in TABLE 2.
2TABLE 2 Comparative Example Composition 1 2 3 4 5 6 Base oil Ether
oil*1 -- -- -- -- -- 86.5 Ester oil*2 86.5 -- 87.5 43 -- --
Synthesized hydrocarbon oil*3 -- 75.5 -- 43 pta 85.5 -- Thickener
Amine Octylamine 6.6 -- -- -- -- 6.6 Cyclohexylamine -- -- -- -- --
-- p-toluidine -- 11.1 -- -- -- -- Diisocyanate MDI*4 6.4 12.9 --
-- -- 6.4 TDI*5 -- -- -- -- -- -- 12-hydroxy Li stearate -- -- 12
13.5 14 -- Antioxidant*6 0.5 0.5 0.5 0.5 0.5 0.5 Properties
Viscosity (at 40.degree. C., mm.sup.2/s) of base oil 38 30 33 32 31
97 Worked penetration (JIS K2220) 240 290 210 220 240 280 Acoustic
properties good bad good not bad not good good Fretting corrosion
resistance bad good not good good bad bad *1:Alkylated diphenyl
ether oil *2:Pentaerythritol ester oil *3:Po1y-.alpha.-olefine oil
*4:Diphenylmethanediisocyanate *5:Tolylenediisocyanate *6:Alkylated
diphenylamine
[0060] As shown in TABLE 1, in each Examples in which the urea
compound was used as the thickener, not less than 50% by weight of
the synthesized hydrocarbon oil, i.e., non-ester oil, was used as
the base oil, there were provided excellent acoustic properties and
fretting corrosion resistance.
[0061] As shown in TABLE 2, in Comparative Examples 1 and 3 in
which the ester oil was used, there were provided poor fretting
corrosion resistance. In Comparative Example 4 in which less than
50% by weight of the synthesized hydrocarbon oil was used, there
was provided less fretting corrosion resistance as compared to
those in Examples. In Comparative Example 6 in which the base oil
containing no synthesized hydrocarbon oil was used, there was
provided poor fretting corrosion resistance, and insufficient
acoustic properties. In Comparative Example 2 in which the urea
compound in which R.sup.2 is an aromatic group, there provided high
worked penetration, and poor acoustic properties.
[0062] In view of the above, it can be concluded that the lubricant
composition of the present invention provides excellent acoustic
properties and fretting corrosion resistance when it is applied to
a bearing. In addition, the worked penetration of the lubricant
composition according to the present invention is within the range
of 220 to 280, thereby further enhancing the acoustic properties
and the fretting corrosion resistance.
[0063] Furthermore, the bearing prelubricating the lubricant
composition of the present invention is noise resistant, and
fretting corrosion resistant. The bearing according to the present
invention is suitable for a spindle bearing for use in an apparatus
for recording and reading electronic information.
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