U.S. patent application number 14/418462 was filed with the patent office on 2015-06-18 for coating composition containing polyamide-imide resin.
The applicant listed for this patent is DOW CORNING TORY CO., LTD.. Invention is credited to Tetsuji Yamaguchi, Jiro Yamashita.
Application Number | 20150166924 14/418462 |
Document ID | / |
Family ID | 49003964 |
Filed Date | 2015-06-18 |
United States Patent
Application |
20150166924 |
Kind Code |
A1 |
Yamaguchi; Tetsuji ; et
al. |
June 18, 2015 |
COATING COMPOSITION CONTAINING POLYAMIDE-IMIDE RESIN
Abstract
A coating composition comprises: (a) a resin solution containing
a polyamide-imide resin and a solvent having a urea bond; and (b) a
powdered solid lubricant. In general, the coating composition
containing a polyamide-imide resin does not raise any concern about
reproductive toxicity and has excellent lubrication durability.
Inventors: |
Yamaguchi; Tetsuji;
(Kanagawa, JP) ; Yamashita; Jiro; (Kanagawa,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DOW CORNING TORY CO., LTD. |
Tokyo |
|
JP |
|
|
Family ID: |
49003964 |
Appl. No.: |
14/418462 |
Filed: |
August 2, 2013 |
PCT Filed: |
August 2, 2013 |
PCT NO: |
PCT/JP2013/071583 |
371 Date: |
January 30, 2015 |
Current U.S.
Class: |
508/128 |
Current CPC
Class: |
C09D 133/24 20130101;
C10M 125/02 20130101; C09D 179/08 20130101; C08K 5/37 20130101;
C08L 79/08 20130101; C10M 149/18 20130101; C10M 133/44
20130101 |
International
Class: |
C10M 149/18 20060101
C10M149/18; C10M 125/02 20060101 C10M125/02; C10M 133/44 20060101
C10M133/44 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 2, 2012 |
JP |
2012-172050 |
Claims
1. A coating composition comprising: (a) a resin solution
containing a polyamide-imide resin and a solvent having a urea
bond; and (b) a powdered solid lubricant.
2. The coating composition according to claim 1, wherein the
solvent having a urea bond has a structure represented by the
following chemical formula (A): ##STR00006## where R.sub.1
represents a saturated hydrocarbon group having from 1 to 9 carbons
and "n" represents an integer from 1 to 10.
3. The coating composition according to claim 2, wherein R.sub.1 is
a saturated hydrocarbon group having from 1 to 3 carbons and "n" is
an integer from 2 to 5 in the solvent having the structure
represented by chemical formula (A).
4. The coating composition according to claim 1, wherein the
content of the polyamide-imide resin in the resin solution is from
10 to 60% by mass.
5. The coating composition according to claim 4, wherein the
content of the polyamide-imide resin in the resin solution is from
10 to 50% by mass.
6. The coating composition according to claim 1, wherein the
polyamide-imide resin is formed by polymerizing a diisocyanate
compound and a trivalent carboxylic acid derivative having an acid
anhydride group in the solvent having a urea bond.
7. The coating composition according to claim 6, wherein the
polyamide-imide resin is formed by reacting the diisocyanate
compound, the trivalent carboxylic acid derivative having an acid
anhydride group, and a dicarboxylic acid compound or diol compound
and a tetracarboxylic acid derivative having two acid anhydride
groups simultaneously.
8. The coating composition according to claim 6, wherein the
polyamide-imide resin is formed by first reacting a dicarboxylic
acid compound or diol compound and an excessive amount of the
diisocyanate compound to synthesize an oligomer having isocyanate
groups at the ends and then adding and reacting the trivalent
carboxylic acid derivative having an acid anhydride group and,
optionally a tetracarboxylic acid derivative having two acid
anhydride groups.
9. The coating composition according to claim 6, wherein the
polyamide-imide resin is formed by reacting the diisocyanate
compound and an excessive amount of the trivalent carboxylic acid
derivative having an acid anhydride group and, optionally a
tetracarboxylic acid derivative having two acid anhydride groups to
synthesize an oligomer having acids or acid anhydride end groups
and then adding and reacting a dicarboxylic compound or diol
compound.
10. The coating composition according to claim 1, wherein the solid
lubricant is selected from the group consisting of fluorine resins,
molybdenum disulfide, and graphite.
11. The coating composition according to claim 1, wherein an
average primary particle diameter of the solid lubricant is from
0.1 to 20 .mu.m.
12. The coating composition according to claim 11, wherein the
average primary particle diameter of the solid lubricant is from
0.1 to 10 .mu.m.
13. The coating composition according to claim 1, wherein the
content of the solid lubricant in the total solid is from 5 to 90%
by mass.
14. The coating composition according to claim 13, wherein the
content of the solid lubricant in the total solid is from 10 to 70%
by mass.
15. A lubricant comprising the coating composition according to
claim 1.
16. A device comprising a surface treatment, wherein the surface
treatment comprises the lubricant according to claim 15.
17. The device according to claim 16, selected from the group
consisting of crank shafts, slide bearings, pistons, gaskets,
gears, door panels, instrument panels, door looks, timing belts,
body seals, glass runs, and weather stripping for sunroofs.
Description
TECHNICAL FIELD
[0001] The present invention relates to a coating composition
containing a polyamide-imide resin.
[0002] Priority is claimed on Japanese Patent Application No.
2012-172050, filed on Aug. 2, 2012, the content of which is
incorporated herein by reference.
BACKGROUND ART
[0003] Polyamide-imide resins are resin materials exhibiting
excellent heat resistance and mechanical strength. Polyamide-imide
resins are therefore used as binder components for coating
compositions having lubricating properties.
[0004] Conventionally, polyamide-imide resins have been synthesized
using amide-based solvents such as N-methylpyrrolidone (NMP),
N-ethylpyrrolidone (NEP), N,N-dimethylacetamide, and
N,N-dimethylformamide. This is because amide-based solvents have
excellent polyamide-imide resin solubility as well as excellent
handleability as solvents.
[0005] However, there is a concern that amide-based solvents have
reproductive toxicity, and there is a trend to regulate the use
thereof primarily in Europe. Accordingly, there is a need to
identify solvents suitable for use in the manufacture of
polyamide-imide resins and in subsequent uses of the resulting
resins to replace amide-based solvents.
[0006] For example, in Japanese Unexamined Patent Application
Publication No. 2008-285660, a polyamide-imide resin formed by
polymerization in a polymerization solvent consisting of only
.gamma.-butyrolactone (GBL) instead of an amide-based solvent and a
polyamide-imide resin composition containing the polyamide-imide
resin are proposed. In Japanese Unexamined Patent Application
Publication No. 2012-62355, a polyamide-imide resin composition
dissolved in a solvent containing .gamma.-butyrolactone and
cyclopentanone is proposed, and a coating composition containing a
solid lubricant is further proposed.
[0007] In Japanese Unexamined Patent Application Publication No.
2007-270074, 1,3-dimethyl-2-imidazolidinone is used as a solvent
when producing a polyamide-imide resin. Further, in Japanese
Unexamined Patent Application Publication No. 2011-210645,
.gamma.-butyrolactone and dimethylimidazolidinone are proposed as a
solvent for forming a polyamide-imide resin coating.
[0008] However, when a polyamide-imide resin composition using
.gamma.-butyrolactone as a solvent is used as a binder for a
lubricant in that the lubrication durability on a product treated
therewith is diminished in comparison to cases in which amide-based
solvents are used.
[0009] The present invention was conceived in order to solve the
problem described above, and the object of the present invention is
to provide a coating composition containing a polyamide-imide resin
which does not raise any concern about reproductive toxicity and
which has excellent lubrication durability.
DISCLOSURE OF INVENTION
[0010] The present inventors arrived at the present invention as a
result of conducting dedicated research in order to achieve the
objective described above. That is, the object of the present
invention is achieved by a coating composition comprising:
(a) a resin solution containing a polyamide-imide resin and a
solvent having a urea bond; and (b) a powdered solid lubricant.
[0011] The solvent having a urea bond preferably has a structure
represented by the following chemical formula (A):
##STR00001##
(where R.sub.1 represents a saturated hydrocarbon group having from
1 to 9 carbons and "n" represents an integer from 1 to 10), and it
is particularly preferable for R.sub.1 to be a saturated
hydrocarbon group having from 1 to 3 carbons and for "n" to be an
integer from 2 to 5.
[0012] The content of the polyamide-imide resin in the resin
solution is for example from 10 to 60% by mass and alternatively
from 10 to 50% by mass.
[0013] The polyamide-imide resin is preferably prepared by
polymerizing a diisocyanate compound and a trivalent carboxylic
acid derivative having an acid anhydride group in a solvent having
a urea bond.
[0014] The solid lubricant is preferably at least one type selected
from the group consisting of fluorine resins, molybdenum disulfide,
and graphite.
[0015] The average primary particle size of the solid lubricant is
for example from 0.1 to 20 .mu.m and alternatively from 0.1 to 10
.mu.m.
[0016] The content of the solid lubricant in the total solid is for
example from 5 to 90% by mass and alternatively from 10 to 70% by
mass.
Effects of Invention
[0017] With the present invention, it is possible to provide a
coating composition containing a polyamide-imide resin which has
excellent lubrication durability without using an amide-based
solvent.
DETAILED DESCRIPTION OF THE INVENTION
[0018] The coating composition of the present invention is a
coating composition comprising:
(a) a resin solution containing a polyamide-imide resin and a
solvent having a urea bond; and (b) a solid lubricant.
[0019] The solvent having a urea bond in the present invention is
not particularly limited as long as it is a solvent which dissolves
the polyamide-imide resin, but the solvent preferably has a
structure represented by the following chemical formula (A):
##STR00002##
(where R.sub.1 represents a saturated hydrocarbon group having from
1 to 9 carbons and "n" represents an integer from 1 to 10).
[0020] Examples of the saturated hydrocarbon group of R.sub.1
include straight-chain or branched alkyl groups such as methyl
groups, ethyl groups, n-propyl groups, isopropyl groups, n-butyl
groups, isobutyl groups, sec-butyl groups, tert-butyl groups,
pentyl groups, hexyl groups, and heptyl groups. A saturated
hydrocarbon group having from 1 to 3 carbons is particularly
preferable.
[0021] "n" represents an integer from 1 to 10, but alternatively an
integer from 2 to 5.
[0022] Examples of the solvent having a urea bond used in the
present invention include the following compounds:
##STR00003##
These solvents may be used alone or as a mixture if necessary.
[0023] The polyamide-imide resin of the present invention is not
particularly limited as long as it is a polymer having an amide
bond and an imide bond in the molecule, but the polyamide-imide
resin can be prepared, for example, by polymerizing a diisocyanate
compound and a trivalent carboxylic acid derivative having an acid
anhydride group in a solvent having a urea bond.
[0024] Examples of the diisocyanate compound used in the
preparation of the polyamide-imide resin include compounds
represented by the following chemical formulas:
##STR00004##
(where X represents O or CH.sub.2).
[0025] Specific examples of diisocyanate compounds include
4,4'-diphenylmethane diisocyanate, 4,4'-diphenylether diisocyanate,
xylylene diisocyanate, 3,3'-dimethylbiphenyl-4,4'-diisocyanate,
3,3'-diphenylmethane diisocyanate,
3,3'-dimethoxybiphenyl-4,4'-diisocyanate, paraphenylene
diisocyanate, hexamethylene diisocyanate, tolylene diisocyanate,
naphthalene diisocyanate, and tolylene diisocyarate. It is
preferable to use an aromatic compound from the perspective of the
mechanical properties, and 4,4'-diphenylmethane diisocyanate and
tolylene diisocyanate are particularly preferable. These
diisocyanate compounds may be used alone or as a mixture if
necessary.
[0026] The trivalent carboxylic acid derivative having an acid
anhydride group used in the preparation of the polyamide-imide
resin is not particularly limited as long as it is a derivative of
a trivalent carboxylic acid having an acid anhydride group which
reacts with isocyanate groups or amino groups, and examples include
compounds represented by the following chemical formulas:
##STR00005##
(where X represents CH.sub.2, CO, SO.sub.2, or O). A trimellitic
acid anhydride is preferable. These trivalent carboxylic acid
derivatives having acid anhydride groups may be used alone or as a
mixture if necessary.
[0027] The polyamide-imide resin may also be prepared by further
adding and polymerizing at least one type of a dicarboxylic acid
compound or diol compound and/or a tetravalent carboxylic acid
derivative having two acid anhydride groups as polymerization
components.
[0028] Examples of the dicarboxylic acid compound used in the
preparation of the polyamide-imide resin include aromatic
dicarboxylic acids such as phthalic acid, isophthalic acid,
terephthalic acid, naphthalene dicarboxylic acid, and oyxdibenzoic
acid and aliphatic dicarboxylic acids such as succinic acid,
glutaric acid, adipic acid, azelaic acid, suberic acid, sebacic
acid, decanedioic acid, dodecanedioc acid, and cyclohexane
dicarboxylic acid. An adipic acid is preferable from the
perspective of the balance of the mechanical properties. These
dicarboxylic acid compounds may be used alone or as a mixture if
necessary.
[0029] Examples of the diol compound used in the preparation of the
polyamide-imide resin include aromatic diol compounds such as
resorcinol, hydroquinones, biphenyl diols, bisphenol A, naphthalene
diols, aromatic polycarbonate diols, and derivatives of aromatic
polycarbonate diols such as aromatic polycarbonate
diol-chloroformic acid diesters and aliphatic diol compounds such
as ethylene glycol, 1,4-butane diol, 1,6-hexane diol, aliphatic
polycarbonate diols, and derivatives of aliphatic polycarbonate
diols such as aliphatic polycarbonate diol-chloroformic acid
diesters. It is preferable to copolymerize at least one type of
monomer selected from the group consisting of aliphatic
polycarbonate diols or derivatives thereof. These diol compounds
may be used alone or as a mixture if necessary.
[0030] An aliphatic polycarbonate diol or a derivative thereof has
the function of improving the workability and adhesiveness of the
coating, and the content in the polyamide-imide resin is preferably
from 1 to 50 mol % and particularly preferably from 5 to 30 mol %.
When the content of the aliphatic polycarbonate diol or a
derivative thereof in the polyamide-imide is within the range
described above, it is possible to impart sufficient workability
and adhesiveness to the coating. When the content of the aliphatic
polycarbonate diol or a derivative thereof exceeds 50 mol %, the
solvent resistance tends to be diminished.
[0031] Examples of commercially available aliphatic polycarbonate
diols or derivatives thereof include trade names PLACCEL CD-205,
205PL, 205HL, 210, 210PL, 210HL, 220, 220PL, and 220HL produced by
Daicel Chemical Industries, Ltd., and these may be used alone or as
a mixture if necessary.
[0032] Examples of the tetravalent carboxylic acid derivative
having two acid anhydride groups used in the preparation of the
polyamide resin include biphenyl tetracarboxylic acid dianhydride,
pyromellitic anhydride, oxydiphthalic acid dianhydride,
benzophenone tetracarboxlic acid dianhydride, diphenyl sulfone
tetracarboxylic acid dianhydride,
(hexafluoroisopropylidene)diphthalic acid dianhydride, and
terphenyl tetracarboxylic acid dianhydride. These tetravalent
carboxylic acid derivatives having two acid anhydride groups may be
used alone or as a mixture if necessary.
[0033] In addition to the compounds described above,
hydroxynaphthoic acid, oxynaphthoic acid, hydroxybiphenyl
carboxylic acid, 1,2-aminododecanoic acid, trimethylolethane,
trimethylolpropane, gluconic acid, lactic acid, fumaric acid,
DL-malic acid, xylitol, D-sorbitol, and DL-alanine may be further
added and polymerized as necessary.
[0034] From the perspective of the molecular weight and the degree
of crosslinking of the polyamide-imide resin to be produced, the
compounded amount of the diisocyanate compound, the trivalent
carboxylic acid derivative having an acid anhydride group, the
dicarboxylic acid compound or diol compound, and the tetravalent
carboxylic acid derivative having two acid anhydride groups is
preferably such that the amount of the diisocyanate compound is
from 0.8 to 1 mole, alternatively from 0.95 to 1.08 moles, and
further alternatively from 1.0 to 1.08 moles with respect to a
total of 1.0 mole of the trivalent carboxylic acid derivative
having an acid anhydride group and, if present, the tetracarboxylic
acid derivative having two acid anhydride groups.
[0035] The compounding ratio of the trivalent carboxylic acid
derivative having an acid anhydride group and the dicarboxylic acid
is preferably from 0.95:0.05 to 0.50:0.50, alternatively from
0.85:0.15 to 0.60:0.40, and alternatively from 0.75:0.25 to
0.65:0.35 as an equivalence ratio. When the compounding ratio is
less than 0.95:0.05, the flexibility of the coating film tends to
be diminished, whereas when the compounding ratio exceeds
0.50:0.50, the heat resistance tends to be diminished.
[0036] The polyamide-imide resin of the present invention can be
prepared by, but is not limited to, the following methods, for
example.
(1) Method of obtaining a polyamide-imide resin by reacting the
diisocyanate compound, the trivalent carboxylic acid derivative
having an acid anhydride group, and, if present, the dicarboxylic
acid compound or diol compound and the tetracarboxylic acid
derivative having two acid anhydride groups all at once; (2) Method
of obtaining a polyamide-imide resin by first reacting the
dicarboxylic acid compound or diol compound and an excessive amount
of the isocyanate compound to synthesize an oligomer having
isocyanate groups at the ends and then adding and reacting the
trivalent carboxylic acid derivative having an acid anhydride group
and, if necessary, the tetracarboxylic acid derivative having two
acid anhydride groups; and (3) Method of obtaining a
polyamide-imide resin by reacting the isocyanate compound and an
excessive amount of the trivalent carboxylic acid derivative having
an acid anhydride group and, if necessary, the tetracarboxylic acid
derivative having two acid anhydride groups to synthesize an
oligomer having acids or acid anhydride groups at the ends and then
adding and reacting the dicarboxylic compound or diol compound.
[0037] The number-average molecular weight of the polyamide-imide
resin of the present invention is for example from 10,000 to
75,000, alternatively from 15,000 to 50,000, and further
alternatively from 20,000 to 35,000. When the number-average
molecular weight of the polyamide-imide resin is less than 10,000,
the strength of the coating film tends to be diminished, whereas
when the number-average molecular weight exceeds 75,000, the
viscosity of the coating composition increases and the operability
at the time of coating is diminished. The number-average molecular
weight of the polyamide-imide resin is sampled at the time of the
synthesis of the resin and measured with a gel permeation
chromatograph (GPC) using the calibration curve of standard
polystyrene.
[0038] The resin solution of the present invention is a solution in
which a polyamide-imide resin is dissolved in a solvent having a
urea bond, and the content of the polyamide-imide resin in the
resin solution is preferably from 10 to 60% by mass and
particularly preferably from 10 to 50% by mass. When the content of
the polyamide-imide resin in the resin solution is within the range
described above, it is possible to impart sufficient lubricating
properties and abrasion resistance to the coating.
[0039] The powdered solid lubricant of the present invention has
the function of improving the slidability of the coating. Examples
of solid lubricants include organic microparticles such as fluorine
resins, polyolefins, and polyamides and inorganic microparticles
such as sulfides, graphite, boron nitride, and metal oxides.
Specific examples include polytetrafluoroethylene,
tetrafluoroethylene-perfluoroalkyl vinyl ether copolymers,
tetrafluoroethylene-hexafluoropropylene copolymers,
tetrafluoroethylene-ethylene copolymers, polyvinylidene fluoride,
polychlorotrifluoroethylene, polyethylene, polyamide, molybdenum
disulfide, tungsten disulfide, graphite, hexagonal boron nitride,
aluminum oxide, and zinc oxide. It is preferable to use at least
one type selected from the group consisting of fluorine resins,
molybdenum disulfide, and graphite.
[0040] The average primary particle diameter of the solid lubricant
of the present invention can be measured by observations using an
electron microscope or with a laser diffraction and scattering
method. The average primary particle diameter of the solid
lubricant is preferably from 0.1 to 20 .mu.m and particularly
preferably from 0.1 to 10 .mu.m.
[0041] The content of the solid lubricant of the present invention
in the total solid is preferably from 5 to 90% by mass and
particularly preferably from 10 to 70% by mass. When the content of
the solid lubricant is within the range described above, it is
possible to sufficiently improve the lubricating properties and the
lubrication durability of the coating.
[0042] The coating composition of the present invention may also
contain one or more types of additives such as a UV absorber, a
photostabilizer, an antioxidant, a thermal polymerization
inhibitor, a leveling agent, an anti-foaming agent a thickening
agent, an anti-settling agent, a pigment (an organic coloration
pigment or an inorganic pigment), a coloration dye, an infrared
radiation absorber, an optical brightener, a dispersing agent,
conductive microparticles, an antistatic agent, an antifogging
agent, a coupling agent, and the like, if necessary, as long as the
object of the present invention is not inhibited.
[0043] The coating composition of the present invention may be
applied with any method. Examples of coating methods that can be
used include dipping methods, spincoat methods, flowcoat methods,
spraying methods, bar-coating methods, gravure coating methods,
roll coating methods, blade coating methods, air knife coating
methods, and the like. A thickness of the coating film is not
particularly limited, but the thickness is preferably from 1 to 50
.mu.m and more preferably from 5 to 30 .mu.m. After application,
the coating film may be dried to remove the solvent and, if
necessary, baked.
EXAMPLES
[0044] The present invention is described in detail below based on
practical examples, but the present invention is not limited to the
practical examples.
Practical Example 1
[0045] Powdered graphite was added to a polyamide-imide resin
solution (produced by Hitachi Chemical Co., Ltd., solid content:
approximately 30% by mass) containing a polyamide-imide resin
dissolved in 1,3-dimethyl-2-imidazolidinone (DMI) prepared in DMI,
so that the content of the powdered graphite was 50 parts by mass
per 100 parts by mass of the polyamide-imide resin, and mixed at
room temperature. This mixture was diluted using DMI so that the
solid content concentration was 15% by mass to form a coating
composition to be used in evaluation tests.
Comparative Example 1
[0046] A polyamide-imide resin solution (produced by Hitachi
Chemical Co., Ltd., HPC-3010) in which a polyamide-imide resin was
dissolved in .gamma.-butyrolactone (GBL) was used, and powdered
graphite was added, so that the content of the powdered graphite
was 50 parts by mass per 100 parts by mass of the polyamide-imide
resin, and mixed at room temperature. This mixture was diluted
using GBL so that the solid content concentration was 15% by mass
to form a coating composition to be used in evaluation tests.
Comparative Example 2
[0047] A coating composition to be used in evaluation tests was
formed in the same manner as in Practical Example 1 with the
exception that the powdered graphite was replaced with silica
(organo silica sol: DMI solution: solid content of approximately
20% by mass).
Reference Example 1
[0048] A polyamide-imide resin solution (produced by Hitachi
Chemical Co., Ltd., HPC-5000) in which a polyamide-imide resin was
dissolved in N-methylpyrrolidone (NMP) was used, and powdered
graphite was added, so that the content of the powdered graphite
was 50 parts by mass per 100 parts by mass of the polyamide-imide
resin, and mixed at room temperature. This mixture was diluted
using NMP so that the solid content concentration was 15% by mass
to form a coating composition to be used in evaluation tests.
Coating Method
[0049] The resulting coating composition was spray-coated onto a
test piece (ring) subjected to sandblasting treatment in advance.
After the test piece was dried for 10 minutes at 80.degree. C., the
test piece was baked for 30 minutes at 240.degree. C. to obtain a
test piece for testing.
Evaluation Method
[0050] Sliding tests were performed under the following conditions
using a block-on-ring tester (LFW-1 tester), and the number of
cycles until the coefficient of friction increased substantially
was measured. Tests were performed with n=2, and the results are
shown in Table 1 as the arithmetic mean thereof.
Sliding Test Conditions
[0051] Ring: SAE 4620 Steel, RC 58-63, 22-28 rms
[0052] Block: SAE 01 Steel, RC 58-63, 4-8 rms
[0053] Sliding environment: immersion in 10W-30 engine oil
[0054] Load: 272 N
[0055] Speed: 72 rpm
TABLE-US-00001 TABLE 1 Test results Practical Comparative
Comparative Reference Example 1 Example 1 Example 2 Example 1
Lubrication 10100 1370 3400 10070 durability
[0056] As is clear from Table 1, it was ascertained that when the
coating composition of Practical Example 1 using
1,3-dimethyl-2-imidazolidinone as a solvent is used, the coating
composition has excellent lubrication durability equivalent to or
better than when N-methylpyrrolidone is used as a solvent. On the
other hand, when the coating composition of Comparative Example 1
using y-butyrolactone as a solvent was used, the lubrication
durability was substantially diminished. When the solid lubricant
was changed from powdered graphite to an organo silica sol, the
lubrication durability was diminished.
INDUSTRIAL APPLICABILITY
[0057] The coating composition of the present invention can be
suitably used in the sliding members of various devices which
require excellent slidability and lubrication durability. For
example, the coating composition can be used for the surface
treatment of crank shafts, slide bearings, pistons, gaskets, gears,
door panels, instrument panels, door looks, timing belts, and body
seals, glass runs, and weather stripping for sunroofs.
* * * * *