U.S. patent application number 11/017912 was filed with the patent office on 2005-06-30 for sliding material comprising fluorine plastic and binder resin.
This patent application is currently assigned to TAIHO KOGYO CO., Ltd.. Invention is credited to Hakamata, Mitsuaki, Kabeya, Yasunori, Kanayama, Hiroshi.
Application Number | 20050139064 11/017912 |
Document ID | / |
Family ID | 34545017 |
Filed Date | 2005-06-30 |
United States Patent
Application |
20050139064 |
Kind Code |
A1 |
Hakamata, Mitsuaki ; et
al. |
June 30, 2005 |
Sliding material comprising fluorine plastic and binder resin
Abstract
The sliding properties of a sliding material which comprises
fluorine-plastic and binder resin are improved, such that it
withstands high speed and high load and varying sliding conditions
from the lubricating-oil free condition to the lubricating-oil
condition and vice versa. A novel sliding material comprises
fluorine-plastic particles having a flat ratio of from 1.5 to 10 in
terms of an average aspect ratio and binder resin.
Inventors: |
Hakamata, Mitsuaki; (Aichi,
JP) ; Kabeya, Yasunori; (Aichi, JP) ;
Kanayama, Hiroshi; (Aichi, JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
TAIHO KOGYO CO., Ltd.
|
Family ID: |
34545017 |
Appl. No.: |
11/017912 |
Filed: |
December 22, 2004 |
Current U.S.
Class: |
92/71 |
Current CPC
Class: |
C08K 3/04 20130101; C08L
77/00 20130101; F16C 2202/50 20130101; F16C 33/20 20130101; C08K
3/30 20130101; C08K 3/36 20130101; C08L 101/00 20130101; C08K 3/22
20130101; C08L 27/12 20130101; C08L 27/18 20130101; C08L 79/08
20130101; C08K 2201/016 20130101; C08L 27/16 20130101; C09D 179/08
20130101; C09D 177/00 20130101; C08K 3/34 20130101; F16C 2208/32
20130101; F04B 27/086 20130101; C08L 77/00 20130101; C08L 2666/04
20130101; C08L 79/08 20130101; C08L 2666/04 20130101; C08L 101/00
20130101; C08L 2666/04 20130101; C09D 177/00 20130101; C08L 2666/04
20130101; C09D 179/08 20130101; C08L 2666/04 20130101 |
Class at
Publication: |
092/071 |
International
Class: |
F01B 003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 25, 2003 |
JP |
2003-429966 |
Claims
1. Sliding material, which comprises fluorine-plastic particles
having a flat ratio of from 1.5 to 10 in terms of an average aspect
ratio and binder resin.
2. Sliding material according to claim 1, wherein said
fluorine-plastic is at least one selected from the group consisting
of polytetrafluoroethylen (PTFE), tetrafluoroethylene
perfluoroalkoxy vinyl ether copolymer(PFA), perfluoroethylene
propylene tetrafluoroethylenen hexafluoropylene(FEP),
ethylene-tetrafluoroethylene copolymer (ETFE),
polyvinyldenefluoride (PVdF), and ethylene-chlorotrifluoroethylene
copolymer (ECTFE).
3. Sliding material according to claim 1, wherein said
fluorine-plastic particles are the calcined fluorine plastic, which
has from 2 to 20 .mu.m of average particle diameter and which is
then crushed.
4. Sliding material according to claim 1, wherein said binder resin
is at least one selected from the group consisting of polyamide
imide and polyimide.
5. Sliding material according to claim 2 consisting of from 5 to
40% by volume of said fluorine plastic particles and from 95 to 60%
by volume of said resin binder in balance.
6. Sliding material according to claim 1, further comprising from 2
to 40% by volume of a solid lubricant selected from the group
consisting of MoS.sub.2 and graphite, the balance being said
fluorine-plastic particles and said binder resin in an amount of
from 98 to 60% by volume.
7. Sliding material according to claim 1, further comprising from
0.1 to 5.0% by volume of a wear-resistant additive selected from
the group consisting of SiO.sub.2, TiO.sub.2, SiC and
Al.sub.2O.sub.3, the balance being said fluorine-plastic particles
and said binder resin in an amount of from 99.1 to 95.0% by
volume.
8. Sliding material according to claim 1, further comprising from 2
to 40% by volume of a solid lubricant, and from 0.1 to 5.0% by
volume of a wear-resistant additive selected from the group
consisting of SiO.sub.2, TiO.sub.2, SiC and Al.sub.2O.sub.3, the
balance being said fluorine plastic and said binder resin.
9. Sliding material according to claim 1, deposited on a sliding
portion of a swash plate of a swash-plate type compressor.
Description
FIELD OF INVENTION
[0001] The present invention relates to sliding material,
particularly sliding material comprising fluorine plastic and
binder resin for bonding the fluorine plastic, more particularly,
the sliding material, which is suited for depositing on the sliding
surface of a swash plate of the swash-plate compressor.
BACKGROUND OF INVENTION
[0002] Fluorine plastic exhibits excellent low-friction property
under the dry lubricating condition. However, in order to improve
the wear resistance of the fluorine plastic-based sliding member,
the fluorine plastic is blended with a solid lubricant such as
MoS.sub.2, graphite and the like and they are bonded with base
resin.
[0003] In the prior art, in order to improve the sliding properties
of the fluorine-plastic based sliding material, the proportion
ratio or amount, and the particle diameter of the additives, have
been adjusted.
[0004] For example, it is disclosed in Japanese Unexamined Patent
Publication No. 7-97517 that a sliding material, which consists of
from 50 to 73% by weight of at least one of polyamide resin and
polyimide resin, from 3 to 15% by weight of polytetrafluoroethylene
(PTFE) resin as solid lubricant, from 20 to 30% of molybdenum
disulfide (MoS.sub.2) and from 2 to 8% by weight of graphite,
exhibits improved wear resistance and initial compatibility under
the conditions of lubrication by graphite contained in the gray
cast iron, low sliding speed of from 0.08 to 1 m/second, and
relatively low load. This material is appropriate for use as the
surface layer of a piston skirt.
[0005] It is disclosed in Japanese Unexamined Patent Publication
No. 2000-136397 that sliding material, which contains from 10 to
40% by weight of calcined granular PTFE and from 3 to 40% by weight
of graphite, the balance being a binder resin, i.e., polyimide
and/or polyamide imide, exhibits improved sliding properties under
the dry condition, and is appropriate as the sliding material of a
wiper arm, which is operated under a low speed of 20 mm/s and
relatively low load. The granular calcined PTFE is prepared by
means of forming PTFE powder by suspension polymerization or
emulsion polymerization, heating the resultant PTFE powder to
melting temperature, i.e., calcining, and then pulverizing the
calcined PTFE powder.
[0006] A swash-plate type compressor, an example of which is shown
in FIG. 1, comprises the following members: cylinder block 1; valve
plates 2; cylinder heads 3; a driving shaft 4; thrust bearings 5;
radial bearings 6; a mechanical seal 7; a swash plate 8; a
swash-plate chamber 10, in which the swash plate 8 is mounted; a
cylinder bore 11; a piston 12; balls 13; ports 15 formed through
the valve plates 2; and ejecting chambers 16; ports (not shown)
communicated with the ejecting chambers16; the ejecting chambers
(not shown); and suction chambers 21. In such swash-plate type
compressor, the driving shaft 4 is rotary driven so as to rotate
the swash plate 8 which is integral with the driving shaft 4. Along
with the rotation of the swash plate 8, the piston 12 is
reciprocated, thereby compressing cooling media within the cylinder
bore 11. The compressed cooling media are ejected into the
respective ejection chambers 16A, 16B via the ports 15A, 15B,
respectively. The compressed cooling media is then sucked into the
cylinder bore 11 via the ports 17, the ejection ports 19, ports 20,
a pair of the suction chambers 21A, 21B, not-shown sucking valves,
and ports 15A formed through the valve plate 2A. The lubricating
oil contained in the compressed cooling media is introduced into
the swash-plate chamber 10 under a mist condition and is fed to the
sliding portions of the swash plate 8, the thrust bearings 5 and
the like.
[0007] The prior art related to the surface treatment of a swash
plate of the swash-plate type compressor includes the
following.
[0008] (1) European Patent No. 713972B1. The Cu or Al alloy is
flame-sprayed, and if necessary, the Pb or Sn coating is, then,
plated on the flame-sprayed layer.
[0009] (2) U.S. Pat. No. 6,123,009. The flame-sprayed Cu layer is
coated with MoS.sub.2 or PTFE coating film.
[0010] (3) Japanese Unexamined Patent Publication No. 02-002475. A
solid-lubricant layer is formed on the aluminum-alloy
substrate.
[0011] (4) Japanese Unexamined Patent Publication No. 2000-265953.
Metallic particles are incorporated in the resin layer.
[0012] (5) Japanese Unexamined Patent Publication No. 2002-005013.
Amorphous hard carbon (DLC) film is formed on the swash plate.
[0013] (6) Japanese Unexamined Patent Publication No.
2002-036902.
[0014] A coating film consisting of a mixture of a solid lubricant
and PEEK resin is formed on the swash plate.
[0015] (7) Japanese Unexamined Patent Publication No. 2002-89437 A
coating film consisting of a mixture of solid lubricant and earthy
graphite resin is formed on the swash plate.
[0016] (8) Japanese Unexamined Patent Publication No. 2002-180961.
A resin coating or a plating layer is deposited on the surface of a
sintered layer.
[0017] The PTFE contained in the coating composition according to
the prior art (2) mentioned above exhibits a low-friction effect at
the sliding with shoes, under such a lubricating-oil poor sliding
condition that a swash-plate type compressor mounted in a vehicle
is started and driven to rotate and is lubricated only by the
cooling media. Specifically, heat generation is suppressed by PTFE.
On the other hand, when it is desired to rapidly cool the interior
of a vehicle, the swash-plate type compressor is operated under the
sliding conditions of high speed and high load. In this case, the
PTFE contained in the coating composition undergoes serious peeling
wear so that the surface is drastically damaged and seizure
occurs.
[0018] The surface treatment according to the prior art (1)
mentioned above provides the coating film consisting only of metal.
There is a possibility that the swash plate subjected to this
surface treatment may seize with respect to the opposite member,
i.e., the shoes, under poor lubricating-oil operating
conditions.
[0019] The surface treatments according the prior arts (3), (4),
(6), and (7) mentioned above provide a solid-lubricant coating film
on the surface of metal. This coating film may incur under such
recent sliding conditions as high-speed rotation and high load a
problem of peeling.
[0020] The surface coating of DLC according to the prior art (5)
mentioned above may crack under the reciprocating load like the
case of resin coating film.
[0021] The prior art (8) mentioned above provides a resin coating
layer or a plating layer on the sintered metallic layer. Since the
contact area between the resin coating layer and the sintered metal
is larger than that of such layer and the non-sintered and hence
non-porous metal, peeling of the resin coating layer is impaired.
However, fundamentally, the peeling of the resin coating cannot be
prevented, because the resin is of low strength and cannot
withstand the load from the shoes.
SUMMARY OF INVENTION
[0022] It is, therefore, an object of the present invention to
improve the sliding properties of a sliding material which is
subjected to high speed and high load and is used under varying
sliding conditions from the lubricating-oil free condition to the
lubricating-oil condition and vice versa.
[0023] It is a particular object of the present invention to lessen
the peeling wear of the sliding material containing PTFE and to
modify its wear mechanism such that little wear occurs gradually
and hence an improved compatible surface is formed.
[0024] In accordance the objects of the present invention, there is
provided a sliding material, which comprises fluorine-plastic
particles having a flat ratio of from 1.5 to 10 in terms of the
average aspect ratio and binder resin.
[0025] There is also provided a sliding material, which comprises
fluorine-plastic particles having a flat ratio of from 1.5 to 10 in
terms of the average aspect ratio and binder resin.
[0026] The fluorine plastic particle is preferably at least one
selected from the group consisting of polytetrafluoroethylen
(PTFE), tetrafluoroethylene perfluoroalkoxy vinyl ether
copolymer(PFA), perfluoroethylene propylene tetrafluoroethylenen
hexafluoropylene(FEP), ethylene-tetrafluoroethylene copolymer
(ETFE), polyvinyldenefluoride (PVdF), and
ethylene-chlorotrifluoroethylene copolymer (ECTFE).
[0027] In the description hereinafter, the fluorine plastic is
described by referring to a representative example of PTFE.
[0028] The granular PTFE particles have smaller surface area than
the flat PTFE particles. The bonding strength of the former
particles with the binder is, therefore, lower than that of the
latter particles. The former particles are, therefore, liable to
separate from the binder, so that peeling of PTFE is induced.
Contrary to this, the sliding material comprising the flat PTFE
particles bonded with the binder has improved compatibility such
that fluid lubrication can be realized on the surface of the
sliding material.
[0029] Meanwhile, under such poor oil condition at the initial
sliding period that only the cooling media lubricates, PTFE
exhibits low-friction property independently upon the shape of PTFE
particles. The friction between the PTFE-containing sliding
material and a shoe is, therefore low during sliding. Specifically,
the extremely thin surface of the PTFE particles having a thickness
of few atom-layers is subject to cleavage. This process takes place
even under extremely weak external force, so that satisfactorily
low friction is realized.
BRIEF DESCRIPTION OF DRAWINGS
[0030] FIG. 1 is a cross-sectional drawing of a swash-plate type
compressor according to an example.
[0031] FIG. 2 is a graph showing a relationship between the average
aspect ratio of the PTFE particles and the seizure time of the PTFE
based sliding material. The average aspect ratio in a range of from
1 to 5 is shown in a larger scale than that of from 5 to 10 and 10
to 15.
[0032] FIG. 3 is a schematic drawing of a sliding layer, which
contains flat PTFE, graphite and MoS.sub.2.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0033] The granular PTFE particles can be flattened by means of
imparting strong shear blending. A bead mill blender, which can
perform strong shear blending, was used to prepare the
solid-lubricant coating-mixture, which may be referred to as the
paint. The average aspect ratio of PTFE particles and the blending
time of the paint were investigated. The seizure time in dependent
on the average aspect ratio was also investigated.
[0034] The composition of the paint was 60% by volume of PAI, 20%
by volume of PTFE, and 20% by volume of graphite for every blended
mixture with the varied average aspect ratio.
[0035] The testing condition was as follows.
[0036] Testing Machine: 3 pin/disc type seizure tester
[0037] Load: 1.2 kN
[0038] Number of Revolutions: 1000 rpm
[0039] Lubricating Condition: R 134 gas
[0040] Opposite Shaft: SUJ 2 (shoe form)
[0041] As is clear from FIG. 2, the seizure time increases with
increase in the average aspect ratio up to approximately 0.2. The
seizure time then decreases because the strength of PTFE decreases
excessively due to flattening. Based on this result, the average
aspect ratio of the PTFE particles is limited in a range of from
1.5 to 10 according to the present invention. A preferable average
aspect ratio is from 2 to 5. The PTFE particles present on a
surface area of 1 mm.times.20 .mu.m were measured in terms of the
ratio of long diameter/short diameter, and the average value of the
measured values was calculated as the average aspect ratio.
[0042] The binder is selected from a heat-resistant resin and is
preferably at least one selected from polyamide imide and
polyimide. Proportion of the fluorine plastic particles is
preferably from 5 to 40% by volume, more preferably from 15 to 35%
by volume based on the total volume of the fluorine plastic
particles and binder, or the total volume of the fluorine plastic
particles, the wear-resistant additives and/or the solid lubricant,
and the binder. Either of these volumes is hereinafter referred to
as the total volume.
[0043] If necessary, at least one solid lubricant selected from the
group consisting of MoS.sub.2 and graphite is contained in a
proportion of from 2 to 20% by volume based on the total volume.
The balance is from 98 to 80% by volume of the fluorine-plastic
particles and the binder resin.
[0044] In addition, at least one wear resistant additive selected
from the group consisting of SiO.sub.2, TiO.sub.2, SiC and
Al.sub.2O.sub.3 may be contained in a proportion of from 0.1 to
5.0% by volume based on the total volume. The balance is from 99.9
to 95.0% by volume of the fluorine-plastic particles and the binder
resin.
[0045] When the paint is subjected to strong shear blending, the
granular PTFE contained is flattened in the paint. For example, the
calcined fluorine plastic having from 2 to 20 .mu.m of average
particle diameter may be blended with the other starting materials
within a bead mill developed by IPROS Corporation, and the sliding
material according to the present invention may be thus
prepared.
[0046] The sliding material according to the present invention can
be preferably used for, for example, the sliding layer of a
swash-plate type compressor and the like, which is operated under
high pressure and high speed and lubricating oil supplied on the
sliding surface.
EXAMPLES
[0047] The paint having the blended composition shown in Tables 1
and 2 was subjected to blending with a propeller mixing
(Comparative Example, untreated PTFE) and blending with strong
shear blending by means of a bead mill (Examples, flattened
PTFE).
[0048] The respective components were as follows.
[0049] PTFE: product of Kitamura Co., Ltd., KTL-8N
[0050] PAI: product of Hitachi Kasei Co., Ltd., HPC-6000
[0051] MoS.sub.2: the average particle-diameter--25 .mu.m; a
product of Sumitomo Mining Lubricant Co., Ltd, Molypowder PB
[0052] Graphite: the average particle-diameter--1 .mu.m, a product
of Nippon Graphite Co., Ltd., CSSP
[0053] The prepared powder was applied on the substrate of a
swash-plate to provide a coating thickness of 20 .mu.m, and the
surface of the coating was polished to form approximately 0.3 .mu.m
Rz of roughness.
[0054] The testing condition was under no lubrication of the
lubricant oil and as follows.
[0055] Testing Machine: 3 pin/disc type seizure tester
[0056] Load: 1.2 kN (4 MPa)
[0057] Number of Revolutions: 1000 rpm (4.2 m/s)
[0058] Lubricating Condition: R 134 gas
[0059] Opposite Shaft: SUJ 2 (shoe form)
[0060] The test results are shown in Table 1.
1 TABLE 1 Proportion of Resin Components vol % Test Result PAI
MoS.sub.2 Gr PTFE Seizure Time (sec) Example 55 20 15 10
140.about.160 PTFE-Flattening 60 -- 20 20 180 or more (Average
Aspect Ratio-3) Comparative Example 55 20 15 10 120.about.140 PTFE
Untreated 60 -- 20 20 130.about.160 (Average Aspect Ratio-1)
[0061] It is apparent from Table 1 that the inventive examples are
superior to the comparative examples in view of the seizure
resistance.
[0062] The test conditions was under lubrication of lubricating oil
and cooling media and were as follows.
[0063] Testing Machine: high-pressure environmental-gas friction
tester
[0064] Lubrication: circulation type (ice-machine
oil+chlorofluoorcaron gas)
[0065] Load: 2 MPa/15 minutes, successive increase to 16 MPa at the
maximum
[0066] Number of Revolutions: 7200 rpm
[0067] Opposite Shaft: SUJ 2 (shoe form)
[0068] The test results are as follows.
2 TABLE 2 Proportion of Resin Components vol % Test Result PAI
MoS.sub.2 Gr PTFE Seizure Wear Example 55 20 15 10 non 3 .mu.m
PTFE-Flattening 60 -- 20 20 non 8 .mu.m (Average Aspect Ratio-3)
Comparative Example 55 20 15 10 non 5 .mu.m PTFE Untreated Slight
(Average Aspect Peeling Ratio-1) 60 -- 20 20 Seizure Peeling
[0069] It is apparent from Table 2 that no peeling occurs in the
inventive examples.
[0070] As is described hereinabove, the present invention provides
sliding material with small wear and free of peeling, when used as
the sliding material on a swash plate of a swash-plate type
compressor.
* * * * *