U.S. patent application number 09/986627 was filed with the patent office on 2002-05-02 for slider formed of fiber-reinforced thermoplastic resin.
This patent application is currently assigned to YKK Corporation. Invention is credited to Hirota, Mutsuo, Ishibashi, Akira, Miyajima, Yoshifumi, Tanaka, Mamoru.
Application Number | 20020051874 09/986627 |
Document ID | / |
Family ID | 16289806 |
Filed Date | 2002-05-02 |
United States Patent
Application |
20020051874 |
Kind Code |
A1 |
Ishibashi, Akira ; et
al. |
May 2, 2002 |
Slider formed of fiber-reinforced thermoplastic resin
Abstract
A formed article of fiber-reinforced thermoplastic resin which
has been adapted for use in a sliding member by restoring the wear
resistance once degraded by the addition of reinforcing fibers to
the normal level is disclosed. This formed article comprises a
fiber-reinforced resin material of a thermoplastic resin containing
reinforcing fibers and incorporating therein additionally as a
sliding property-imparting agent a material having a storage
elastic modulus in the range of 3.5.times.10.sup.8 Pa to
5.0.times.10.sup.8 Pa in a service temperature range of 30.degree.
C. to 70.degree. C. The ratio of incorporation of the sliding
property-imparting agent is properly in the range of 4 to 10% by
weight when the matrix resin is a polyamide-based resin or 4 to 20%
by weight when the matrix resin is a thermoplastic resin other than
the polyamide-based resin, respectively based on the total weight
of the resin and the reinforcing fibers.
Inventors: |
Ishibashi, Akira;
(Toyama-shi, JP) ; Tanaka, Mamoru; (Toyama-ken,
JP) ; Hirota, Mutsuo; (Toyama-ken, JP) ;
Miyajima, Yoshifumi; (Kurobe-shi, JP) |
Correspondence
Address: |
FINNEGAN, HENDERSON, FARABOW, GARRETT &
DUNNER LLP
1300 I STREET, NW
WASHINGTON
DC
20005
US
|
Assignee: |
YKK Corporation
|
Family ID: |
16289806 |
Appl. No.: |
09/986627 |
Filed: |
November 9, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09986627 |
Nov 9, 2001 |
|
|
|
09324766 |
Jun 3, 1999 |
|
|
|
Current U.S.
Class: |
428/297.4 ;
428/299.1; 428/299.4 |
Current CPC
Class: |
C08L 23/00 20130101;
C08L 27/12 20130101; C08L 23/00 20130101; C08L 23/00 20130101; C08L
27/12 20130101; C08L 27/12 20130101; C08L 69/00 20130101; C08L
77/00 20130101; C08L 67/02 20130101; Y10T 24/2561 20150115; C08L
67/02 20130101; Y10T 428/249945 20150401; Y10T 428/24994 20150401;
C08J 5/10 20130101; C08J 5/043 20130101; C08J 5/04 20130101; C08L
69/00 20130101; C08J 5/041 20130101; C08L 67/02 20130101; C08K 7/02
20130101; A44B 19/26 20130101; C08L 77/00 20130101; C08L 69/00
20130101; C08L 77/00 20130101; C08J 5/042 20130101; Y10T 24/25
20150115; Y10T 428/249946 20150401 |
Class at
Publication: |
428/297.4 ;
428/299.4; 428/299.1 |
International
Class: |
B32B 027/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 24, 1998 |
JP |
10-192349 |
Claims
What is claimed is:
1. A formed article of thermoplastic resin, comprising a
fiber-reinforced resin material of a thermoplastic resin containing
reinforcing fibers and incorporating therein additionally as a
sliding property-imparting agent a material having a storage
elastic modulus in the range of 3.5.times.10.sup.8 Pa to
5.0.times.10.sup.8 Pa in a service temperature range of 30.degree.
C. to 70.degree. C.
2. The formed article according to claim 1, wherein said
thermoplastic resin is selected from the group consisting of
polybutylene terephthalate, polyethylene terephthalate,
polycarbonate, and polyamide.
3. The formed article according to claim 1, wherein said
thermoplastic resin is polybutylene terephthalate.
4. The formed article according -to claim 1, wherein said sliding
property-imparting agent is selected from the group consisting of
fluoropolymers and polyethylene.
5. The formed article according -to claim 1, wherein said sliding
property-imparting agent is polytetrafluoroethylene.
6. The formed article according to claim 1, wherein said
reinforcing fiber is present in an amount of 20 to 60% by weight,
based on the weight of said thermoplastic resin.
7. The formed article according to claim 1, wherein said
reinforcing fiber is at least one member selected from the group
consisting of glass fibers, carbon fibers, and metal fibers.
8. The formed article according to claim 1, wherein said formed
article is a slider for use in a slide fastener.
9. A formed article of thermoplastic resin, comprising a
fiber-reinforced resin material of a polyamide-based resin
containing reinforcing fibers and incorporating therein
additionally as a sliding property-imparting agent a material
having a storage elastic modulus in the range of 3.5.times.10.sup.8
Pa to 5.0.times.10.sup.8 Pa in a service temperature range of
30.degree. C. to 70.degree. C. at a ratio in the range of 4 to 10%
by weight, based on the total weight of said resin and said
reinforcing fibers.
10. The formed article according to claim 9, wherein said sliding
property-imparting agent is selected from the group consisting of
fluoropolymers and polyethylene.
11. The formed article according to claim 9, wherein said sliding
property-imparting agent is polytetrafluoroethylene.
12. The formed article according to claim 9, wherein said
reinforcing fiber is present in an amount of 20 to 60% by weight,
based on the weight of said polyamide-based resin.
13. The formed article according to claim 9, wherein said
reinforcing fiber is at least one member selected from the group
consisting of glass fibers, carbon fibers, and metal fibers.
14. The formed article according to claim 9, wherein said formed
article is a slider for use in a slide fastener.
15. A formed article of thermoplastic resin, comprising a
fiber-reinforced resin material of a thermoplastic resin (excluding
a polyamide-based resin) containing reinforcing fibers and
incorporating therein additionally as a sliding property-imparting
agent a material having a storage elastic modulus in the range of
3.5.times.10.sup.8 Pa to 5.0.times.10.sup.8 Pa in a service
temperature range of 30.degree. C. to 70.degree. C. at a ratio in
the range of 4 to 20% by weight, based on the total weight of said
resin and said reinforcing fibers.
16. The formed article according to claim 15, wherein said
thermoplastic resin is selected from the group consisting of
polybutylene terephthalate, polyethylene terephthalate, and
polycarbonate.
17. The formed article according to claim 15, wherein said
thermoplastic resin is polybutylene terephthalate.
18. The formed article according to claim 15, wherein said sliding
property-imparting agent is selected from the group consisting of
fluoropolymers and polyethylene.
19. The formed article according to claim 15, wherein said sliding
property-imparting agent is polytetrafluoroethylene.
20. The formed article according to claim 15, wherein said
reinforcing fiber is present in an amount of 20 to 60% by weight,
based on the weight of said thermoplastic resin.
21. The formed article according to claim 15, wherein said
reinforcing fiber is at least one member selected from the group
consisting of glass fibers, carbon fibers, and metal fibers.
22. The formed article according to claim 15, wherein said formed
article is a slider for use in a slide fastener.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a formed article of
fiber-reinforced thermoplastic resin excelling in wear resistance,
and more particularly to a formed article of fiber-reinforced
thermoplastic resin manufactured in the shape of a varying sliding
member by subjecting to injection molding or extrusion molding a
fiber-reinforced thermoplastic resin having the sliding quality
thereof improved by incorporation therein of a suitable amount of a
material possessing a storage elastic modulus within a prescribed
range as a sliding property-imparting agent. The term "sliding
property-imparting agent" used herein means a substance which is
capable of improving a sliding property of the formed article of
thermoplastic resin or lowering a friction coefficient thereof.
[0003] 2. Description of the Prior Art
[0004] Heretofore, it has been customary to use a resin excelling
in heat resistance and mechanical strength for resinous products
which are used in sliding members. Specifically, the idea
purporting that the resin to be used ought to acquire improved wear
resistance by the step of increasing the rigidity of the resin
prevails. This increase of the rigidity of resin is generally
attained by the method of incorporating reinforcing fibers in the
resin. When the resin obtained by this method is used particularly
for the sliding member in a slide fastener, however, the sliding
member has only low durability because it exhibits such notably
inferior wear resistance that in a reciprocating closing test
performed in accordance with Japanese Industrial Standard (JIS) S
3015, it becomes inoperative after about 60 open-close
reciprocations.
SUMMARY OF THE INVENTION
[0005] When the formed article of thermoplastic resin is found to
be deficient in rigidity, the thermoplastic resin used therein is
generally made to incorporate therein a suitable amount of
reinforcing fibers by way of compensation for shortage of
mechanical strength. In terms of wear resistance, however, the
reality of the reinforced thermoplastic resin is that the
reinforcing fibers cause the thermoplastic resin to lose wear
resistance because they are fated to function conversely as an
abrasive.
[0006] An object of the present invention is to provide a formed
article of thermoplastic resin which, with the view of improving
the wear resistance of such a fiber-reinforced thermoplastic resin
as mentioned above notably degraded in consequence of the addition
of reinforcing fibers, incorporates therein a suitable amount of a
material possessing an appropriate storage elastic modulus in the
standard range of service temperatures or operating temperatures as
a sliding property-imparting agent and acquires the improvement of
wear resistance and proves fit for use as a sliding member.
[0007] To accomplish the object mentioned above, the basic mode of
the present invention resides in providing a formed article of
thermoplastic resin, which is characterized by comprising a
fiber-reinforced resin material of a thermoplastic resin containing
reinforcing fibers and incorporating therein additionally as a
sliding property-imparting agent a material having a storage
elastic modulus in the range of 3.5.times.10.sup.8 Pa to
5.0.times.10.sup.8 Pa in a service temperature range of 30.degree.
C. to 70.degree. C.
[0008] One specific mode of the present invention provides a formed
article of thermoplastic resin, which is characterized by
comprising a fiber-reinforced resin material of a polyamide-based
resin containing reinforcing fibers and incorporating therein
additionally as a sliding property-imparting agent a material
having a storage elastic modulus in the range of 3.5.times.10.sup.8
Pa to 5.0.times.10.sup.8 Pa in a service temperature range of
30.degree. C. to 70.degree. C. at a ratio in the range of 4 to 10%
by weight, based on the total weight of the resin and the
reinforcing fibers mentioned above.
[0009] Another specific mode of the present invention provides a
formed article of thermoplastic resin, which is characterized by
comprising a fiber-reinforced resin material of a thermoplastic
resin (excluding a polyamide-based resin) containing reinforcing
fibers and incorporating therein additionally as a sliding
property-imparting agent a material having a storage elastic
modulus in the range of 3.5.times.10.sup.8 Pa to 5.0.times.10.sup.8
Pa in a service temperature range of 30.degree. C. to 70.degree. C.
at a ratio in the range of 4 to 20% by weight, based on the total
weight of the resin and the reinforcing fibers mentioned above.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Other objects, features, and advantages of the invention
will become apparent from the following description taken together
with the drawings, in which:
[0011] FIG. 1 is a graph showing changes in amount of abrasion
found in an abrasion resistance test performed on polybutylene
terephthalate containing 30% by weight of glass fibers and a
fiber-reinforced resin containing the glass fiber-containing
polymer just mentioned and 10% by weight of polytetrafluoroethylene
additionally incorporated therein;
[0012] FIG. 2 is a graph showing changes in the storage elastic
modulus of polytetrafluoroethylene and that of polybutylene
terephthalate containing 30% by weight of glass fibers with
temperature;
[0013] FIG. 3 is a graph showing changes in the storage elastic
modulus of polyethylene and that of polybutylene terephthalate
containing 30% by weight of glass fibers with temperature;
[0014] FIG. 4 is a graph showing changes in the amount of abrasion
found in an abrasion resistance test performed on a polyamide-based
resin containing 50% by weight of glass fibers and species of this
fiber-reinforced resin just mentioned additionally incorporating
therein 5% by weight, 10% by weight, and 20% by weight respectively
of polyethylene;
[0015] FIG. 5 is a graph showing the range of storage elastic
modulus of a material usable as a sliding property-imparting agent
in the present invention;
[0016] FIG. 6 is a graph showing the results of an abrasion
resistance test performed on test pieces prepared from a
polyamide-based resin containing 50% by weight of glass fibers and
species of this fiber-reinforced resin just mentioned additionally
incorporating therein 2.5% by weight, 5% by weight, 10% by weight,
and 20% by weight respectively of polyethylene;
[0017] FIG. 7 is a plan view illustrating one embodiment of a slide
fastener made of a synthetic resin;
[0018] FIG. 8 is a plan view illustrating another embodiment of a
slide fastener made of a synthetic resin;
[0019] FIG. 9 is a plan view illustrating still another embodiment
of a slide fastener made of a synthetic resin; and
[0020] FIG. 10 is a partially cutaway plan view illustrating
another embodiment of a slide fastener made of a synthetic
resin.
DETAILED DESCRIPTION OF THE INVENTION
[0021] The present inventors, in consequence of a diligent study
performed with a view to improving the wear resistance of the
thermoplastic resin reinforced with reinforcing fibers, have taken
notice of the correlation between the temperature dependence of the
elastic modulus representing the viscoelastic behavior of a
material used as a sliding property-imparting agent, namely the
storage elastic modulus representing the elasticity having no
energy dissipation and the loss elastic modulus concerning energy
dissipation (Source: Seiichi Nakahama et al., "Essential Polymer
Science", Kodansha Scientific, 1998, pp. 218 -222), and the wear
resistance of a fiber-reinforced resin incorporating therein the
sliding property-imparting agent and have consequently discovered
that when a material possessing an appropriate storage elastic
modulus in the standard range of service temperatures is added as a
sliding property-imparting agent in a suitable amount to a
fiber-reinforced resin, the material consequently produced acquires
notably improved wear resistance as evinced by the fact that it
retains proper elasticity even after the temperature thereof has
been slightly elevated to the service temperature range or
operating temperature range (generally 30-70.degree. C.) of a
sliding member, which is produced by the frictional heat caused by
the sliding motion thereof. The present invention has been
perfected as a result. That is, the present invention is
characterized by adding a material having a storage elastic modulus
in the range of 3.5.times.10.sup.8 Pa to 5.0.times.10.sup.8 Pa in a
service temperature range of 30.degree. C. to 70.degree. C. as a
sliding property-imparting agent in a proper amount to a
fiber-reinforced thermoplastic resin thereby providing a material
which permits production of a formed article vested with the wear
resistance heretofore unattainable by the formed articles of this
class. To be specific, the impartation of the excellent wear
resistance is attained by mixing the material possessing the
storage elastic modulus in the range mentioned above as a sliding
property-imparting agent at a prescribed quantitative ratio with
reinforcing fibers and a thermoplastic resin or with a
thermoplastic resin containing reinforcing fibers and then molding
the resultant mixture by the injection molding technique or the
extrusion molding technique thereby obtaining a formed article.
[0022] When a sliding part formed of a thermoplastic resin
containing such reinforcing fibers as glass fibers and a sliding
part formed of a similar thermoplastic resin but containing no
reinforcing fibers are compared regarding wear resistance and the
results of the comparison are rated in terms of the number of
sliding motions performed by the sliding part without disengagement
from fastener chains and the amount of abrasion suffered to be
sustained, it is demonstrated that the former sliding part suffers
a marked decrease in the number of sliding motions and an increase
in the amount of abrasion. The results indicate that the former
sliding part possesses very inferior wear resistance to the latter
sliding part. The very poor wear resistance is logically explained
by a supposition that the reinforcing fibers such as glass fibers
function as a reinforcing material so long as they are present in
the formed article but that once they are liberated to the surface
of the formed article, they function as an abrasive and shave the
sliding part itself and the part which is in contact therewith
because they have higher rigidity than the thermoplastic resin
serving as the matrix. The use of the reinforcing fibers has the
precondition that they be utilized for a member which is in need of
high strength. Wherever a thermoplastic resin is used for this
member, the use of the reinforcing fibers is indispensable.
[0023] In the light of the conventional idea mentioned above and
the issues arising therefrom, the present invention has been
attained from the following viewpoint. In short, the present
invention prevents the formed article of thermoplastic resin
containing such reinforcing fibers from abrasion by causing the
formed article to incorporate a more soft material, namely a
material possessing lower storage elastic modulus and loss elastic
modulus than the fiber-reinforced thermoplastic resin within a
prescribed temperature range, as a sliding property-imparting agent
in a proper amount.
[0024] The proper ratio of incorporation of the sliding
property-imparting agent varies with the kind of matrix resin. It
is in the range of 4 to 10% by weight in the case of a
polyamide-based resin or in the range of 4 to 20% by weight in the
case of other thermoplastic resin than the polyamide-based resin,
based on the total weight of the resin and the reinforcing fibers.
If the ratio of incorporation of the sliding property-imparting
agent is less than the lower limit of the range mentioned above,
the produced material will not acquire fully satisfactory wear
resistance. Conversely, if the ratio is larger than the upper limit
of the range, the formed article consequently obtained will be
deficient in strength. Further, since the material which is
suitable as the sliding property-imparting agent is generally
expensive, the excess of the ratio constitutes itself a major
factor for boosting the cost of production of the formed article
and proves unfavorable from the economic point of view.
[0025] The sliding property-imparting agent mentioned above imposes
no restriction particularly but requires only to be a material
which exhibits a storage elastic modulus in the range of
3.5-5.0.times.10.sup.8 Pa in the service temperature range,
30-70.degree. C., of a sliding part. Every material which fulfills
this requirement, therefore, is usable. As concrete examples of the
material, fluoropolymers such as polytetrafluoroethylene (PTFE),
tetrafluoroethylene-hexafluoroethylene copolymer (FEP),
tetrafluoroethylene-perfluoroalkylvinyl ether copolymer (PFA),
modified tetrafluoroethylene-ethylene copolymer (E/TFE polymer),
polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene
(PCTFE), chlorotrifluoroethylene-ethylene copolymer (E/CTFE
polymer), and polyvinyl fluoride (PVF) and polyethylene may be
cited. Among other materials enumerated above,
polytetrafluoroethylene proves particularly favorable.
[0026] Now, the operation of the present invention will be
described below by reference to the accompanying drawings.
[0027] FIG. 1 shows the changes in the amount of abrasion found in
an abrasion resistance test performed on a test piece prepared from
a fiber-reinforced resin produced by combining polybutylene
terephthalate (PBT) with 30% by weight, based on the weight of PBT,
of glass fibers (GF) and a test piece prepared from a
fiber-reinforced resin produced by combining the fiber-reinforced
resin mentioned above with 10% by weight, based on the weight of
the fiber-reinforced resin, of polytetrafluoroethylene (PTFE). In
the diagram, the abscissa axis is the scale of the atmospheric
temperature of the site of abrasion test and the ordinate axis the
scale of the weight percentage of the amount of the test piece
remaining after a prescribed period of the test, with the weight of
the test piece prior to the test taken as 100%.
[0028] The abrasion test was performed by using a method of keeping
a disklike abrading member in rotation and pressing with a weight
the test piece against the rotating abrading member from above.
During this test, the load was set at 0.5 kgf/mm.sup.2 and the
speed at 19.4 m/min. The duration of the test was set at 30
minutes.
[0029] As shown in FIG. 1, the fiber-reinforced resin incorporating
therein in a proper amount the resin (PTFE) definitely inferior in
terms of strength and deficient in storage elastic modulus as a
sliding property-imparting agent, as compared with the
fiber-reinforced thermoplastic resin, did not show the effect of
addition of the resin in the neighborhood of normal room
temperature of about 20.degree. C. but, in a temperature range
exceeding the neighborhood of 30.degree. C., all the species of
fiber-reinforced resin showed increases in the absolute amount of
abrasion, though the increases were small as compared with the
increase found in the fiber-reinforced thermoplastic resin omitting
the incorporation of the resin of low storage elastic modulus.
These results indicate the added agent brought an improvement in
wear resistance. Incidentally, this trend continued to exist up to
the neighborhood of 80.degree. C.
[0030] Thus, the wear resistance of the thermoplastic resin
reinforced with fibers was markedly improved in an approximate
temperature range of 30.degree. C. to 80.degree. C. by the
incorporation therein in a proper amount of the resin (PTFE) as a
sliding property-imparting agent having a lower storage elastic
modulus than the fiber-reinforced resin. The temperature dependence
of the storage elastic modulus of the sliding property-imparting
agent (PTFE) was as shown in FIG. 2. The storage elastic modulus
was measured by the use of an automatic dynamic viscoelasticity
measuring device.
[0031] In FIG. 2, the storage elastic modulus of the
fiber-reinforced thermoplastic resin (PBT+30% by weight of GF)
omitting the incorporation of PTFE was shown together with the
storage elastic modulus of PTFE. It is easily noted from the graph
that the fiber-reinforced thermoplastic resin omitting the
incorporation of the PTFE showed a large storage elastic modulus
within the range of service temperature.
[0032] Still more important point is the fact that the effect of
the material added as the sliding property-imparting agent did not
manifest at 20.degree. C. and it manifested beyond a temperature of
about 30.degree. C. This fact implies that the temperature
dependence of the sliding property-imparting agent participated
largely in the wear resistance of the fiber-reinforced
thermoplastic resin. To be more specific numerically, it is
important that the storage elastic modulus of the sliding
property-imparting agent be not more than 5.times.10.sup.8 Pa at
temperatures exceeding 30.degree. C.
[0033] As respects the manifestation of the effect at temperatures
exceeding 30.degree. C., when a sliding member was caused to slide,
specifically when a slider part for a slide fastener, for example,
was set on a fastener chain and left reciprocating at normal room
temperature, the temperature of the slider part rose up to
35.degree. C. This fact is thought to imply that the temperatures
exceeding 30.degree. C. constituted themselves a practically
effective range.
[0034] To demonstrate this point more precisely, substances having
various storage elastic moduli were selected as materials for
incorporation as a sliding property-imparting agent and tested for
abrasion resistance and measured for storage elastic modulus. To be
specific, a test piece prepared from a fiber-reinforced resin
combining a polyamide-based resin (made by Mitsubishi Engineering
Plastics K. K. and sold under the trademark designation of "Reny
1022 HS") with 50% by weight of glass fibers (GF) and test pieces
prepared from fiber-reinforced resins combining the
fiber-reinforced resin mentioned above with 5% by weight, 10% by
weight, and 20% by weight respectively of polyethylene (PE)
possessing such a storage elastic modulus as shown in FIG. 3 and
adopted as a sliding property-imparting agent were tested for
abrasion resistance and the results of the test were compared. The
results are shown in FIG. 4. It is clearly noted from FIG. 4 that
the effect of the polyethylene as the sliding property-imparting
agent manifested conspicuously in the neighborhood of 60.degree.
C.
[0035] In the diagram, the abscissa axis is the scale of the
atmospheric temperature of the site of test and the ordinate axis
the scale of the weight percentage of the amount of the test piece
remaining after a prescribed period of the test, with the weight of
the test piece prior to the test taken as 100%. The abrasion test
was performed in the same manner as the abrasion test described
above in connection with FIG. 1.
[0036] It deserves attention that the data of FIG. 4 also show a
sign of improvement of the wear resistance in the neighborhood of
60.degree. C. As shown in FIG. 3, the storage elastic modulus of
the polyethylene (the sliding property-imparting agent) in the
neighborhood of 60.degree. C. was certainly not more than
5.times.10.sup.8 Pa.
[0037] The materials which are usable as the sliding
property-imparting agent in the present invention have storage
elastic moduli which fall in the range illustrated in FIG. 5.
[0038] As shown in FIG. 5, in order for the material used as the
sliding property-imparting agent in the formed article of the
fiber-reinforced thermoplastic resin to manifest the effect thereof
properly, it is an important requirement that the storage elastic
modulus of the material is not more than 5.times.10.sup.8 Pa in a
temperature range of 30.degree. C. to 70.degree. C. So long as the
storage elastic modulus of the material as the sliding
property-imparting agent is not less than 3.5.times.10.sup.8 Pa,
this material does no harm to the high strength aimed primarily at
by the fiber-reinforced thermoplastic fiber and is thought to be
practically useful.
[0039] The temperature range up to 70.degree. C. is thought to
constitute itself a practical range in view of the environment of
the use to be found for the sliding member, a possibly specific
outlet for the product such as, for example, the slider for the
slide fastener.
[0040] The major point of the present invention, as described
above, resides in incorporating in the thermoplastic resin
reinforced with fibers a material possessing a storage elastic
modulus in the range of 3.5.times.10.sup.8 Pa to 5.0.times.10.sup.8
Pa in a temperature range of 30.degree. C. to 70.degree. C. as a
sliding property-imparting agent.
[0041] As shown in FIG. 2, polytetrafluoroethylene perfectly meets
the condition of the storage elastic modulus imposed on the
material which is usable as the sliding property-imparting agent in
the present invention. The use of this polytetrafluoroethylene or
an analogous compound thereof as the sliding property-imparting
agent, therefore, is advantageous, with the chemical stability
thereof as a contributory factor.
[0042] Further, with a view to making the wear resistance manifest
to better advantage, the proper amount of incorporation of the
sliding property-imparting agent (polyethylene) into the
fiber-reinforced thermoplastic resin [the polyamide-based resin (
Reny 1022 HS)+50% by weight of glass fibers] was investigated. The
results are shown in FIG. 6.
[0043] In FIG. 6, the abscissa axis is the scale of the
polyethylene content and the ordinate axis the scale of the weight
percentage of the residual amount of the test piece after the
abrasion test (the original amount prior to the test taken as
100%). The abrasion test herein was performed in the same manner as
the abrasion test explained above regarding FIG. 1.
[0044] It is clearly noted from FIG. 6 that the sliding
property-imparting agent incorporated in the fiber-reinforced
thermoplastic resin manifests the effect thereof when the amount of
the incorporation is not less than 4% by weight based on the weight
of the fiber-reinforced thermoplastic resin. If the amount of the
incorporation of the sliding property-imparting agent is less than
4% by weight, no sign of improvement will be seen in the wear
resistance. Conversely, if the amount of the incorporation is
unduly large, this excess, though serving to improve the wear
resistance, will notably impair the strength which forms the
primary object of the use of the formed article of the
fiber-reinforced thermoplastic resin. Further, the use of such an
expensive material as polytetrafluoroethylene in the unduly large
amount mentioned above deprives the present invention significantly
of the practicality thereof because it results directly in boosting
the cost of production. It is, therefore, proper to set the upper
limit of the amount of incorporation of the sliding
property-imparting agent at 10% by weight in the case of the
polyamide-based resin or at 20% by weight in the case of other
thermoplastic resin, respectively as the matrix resin, based on the
weight of the fiber-reinforced thermoplastic resin.
[0045] The thermoplastic resin to be used in the present invention
is fundamentally required to be a resin possessed of high rigidity.
As concrete examples of the resin fulfilling this requirement,
polybutylene terephthalate, polyethylene terephthalate,
polycarbonate, and polyamide may be cited. The thermoplastic resin
is further preferred to be possessed of a higher glass transition
point, Tg, than the Tg of the sliding property-imparting agent. The
reason for the requirement mentioned above is that the merit of
utilizing the soft material as the sliding property-imparting agent
is not obtained unless a difference of certain degree exists in
rigidity, or storage elastic modulus, between the thermoplastic
resin and the sliding property-imparting agent. From this point of
view, polybutylene terephthalate or a polyamide-based resin is used
particularly advantageously.
[0046] The reinforcing fibers to be used in the present invention
are incorporated in the thermoplastic resin for the purpose of
increasing the strength of this resin. As previously pointed out,
however, the reinforcing fibers induce the thermoplastic resin
incorporating them therein to suffer notable degradation of the
wear resistance as compared with the same resin incorporating no
reinforcing fiber at all therein. The best measure to improve the
wear resistance, therefore, would consist in either totally
omitting or decreasing to the fullest possible extent the use of
the reinforcing fibers, which are the cause for the degradation of
wear resistance. The sliding member made of resin, however,
requires to aim simultaneously at improving wear resistance and
acquiring high strength. In the case of adopting a thermoplastic
resin for use in the sliding member, the use of such reinforcing
fibers ought to prove indispensable when the behavior of these
fibers is relied on to attain the improvement of the strength. As
the point in balancing the factor of this strength against that of
the wear resistance, therefore, it is essential that the amount of
incorporation of the reinforcing fibers be retained within the
range of 20 to 60% by weight, based on the weight of the
thermoplastic resin. As the reinforcing fibers, glass fibers,
carbon fibers, and metal fibers which are invariably light of
weight and inexpensive can be used. These species of reinforcing
fibers may be used either singly or in the form of a mixture of two
or more members.
[0047] In the present invention, the thermoplastic resin,
reinforcing fibers, and sliding property-imparting agent which have
been manufactured respectively by well-known methods are
effectively used without any particular restriction. Further, as to
polytetrafluoroethylene, polybutylene terephthalate, polyamide,
glass fibers, carbon fibers, and metal fibers, those manufactured
respectively by well-known methods are effectively used without any
particular restriction.
[0048] The method for producing the formed article contemplated by
the present invention is not particularly discriminated. The most
typical of various methods available for the production comprises
the steps of preparatorily mixing polybutylene terephthalate by
means of a kneading machine with a prescribed amount of glass
fibers having compatibility imparted thereto by a surface
treatment, adding a prescribed amount of polytetrafluoroethylene to
the glass fiber-containing polybutylene terephthalate, further
kneading them, and molding the resultant resin by means of an
injection molding machine. This method allows the formed article of
thermoplastic resin excelling in wear resistance and enjoying high
strength to be produced easily with fine reproducibility.
[0049] The kneading temperature imposes no restriction particularly
but requires only to exceed the temperature at which the
thermoplastic resin to be used is melted. The kneading method to be
used may be a method having no use for a kneading device, i.e. a
method called dry blending. The sequence in which the components
are mixed imposes no restriction particularly. The components may
be mixed in an arbitrary sequence or they may be mixed altogether
at once.
[0050] The formed article of thermoplastic resin according to the
present invention which excels in wear resistance brings a
prominent effect when it is used in a slider member for a slide
fastener. The slider for a slide fastener which is manufactured,
for example, by using polybutylene terephthalate as a thermoplastic
resin, glass fibers as reinforcing fibers, and
polytetrafluoroethylene as a sliding property-imparting agent,
mixing them, and molding the resultant mixture in a relevant shape,
when tested for wear resistance as rated in terms of the number of
open-close reciprocations tolerated by the slide fastener in
accordance with Japanese Industrial Standard (JIS) S 3015, is found
to withstand about 4,000 open-close reciprocations. In contrast,
the slider which is prepared by following the procedure mentioned
above while omitting the addition of the sliding property-imparting
agent tolerates only about 60 open-close reciprocations.
[0051] The formed articles of thermoplastic resin according to the
present invention can be utilized as slider members in slide
fasteners which are made of varying kinds of synthetic resins.
Several embodiments are illustrated in FIG. 7 through FIG. 10.
[0052] FIG. 7 illustrates a slide fastener 1 which is used for
opening and closing the opening in a garment or a bag and depicts
the form of a product having the upper and lower ends of laterally
paired fastener stringers 2 cut off. The fastener stringers 2 are
composed of fastener tapes 3 made of synthetic resin and a row of
coupling elements (coiled coupling elements) 4 made of synthetic
resin attached fast to each of the opposed longitudinal edges of
the fastener tapes 3. The fastener tapes 3 are formed by weaving
and/or knitting synthetic resin fibers, manufactured from a
non-woven fabric, or made of a sheet of synthetic resin. The
coupling elements 4 are known in various forms such as, for
example, those of the type obtained by injection molding the
individual coupling elements and simultaneously attaching them fast
to the edges of the fastener tapes, the continuous coupling
elements such as the coiled coupling elements obtained by winding a
monofilament of synthetic resin in the shape of a coil and the
so-called zigzag coupling elements obtained by alternately
connecting vertically in a zigzagging pattern in the longitudinal
direction the portions bent in the shape of a letter U in the
lateral direction in a plane, and the extrusion molded coupling
elements obtained by attaching the opposite end portions of the
individual coupling elements by means of extrusion molding to the
two separate connecting cords (core cords) laid parallel to each
other in the longitudinal direction thereby forming a composite
resembling a ladder and bending the composite in the shape of a
letter U around the longitudinal center line thereof. The reference
numeral 5 denotes a slider which is slidable along the opposed rows
of coupling elements for making and breaking engagement of the
coupling elements. The slider 5 is formed of the fiber-reinforced
thermoplastic resin of the present invention incorporating the
sliding property-imparting agent therein.
[0053] A slide fastener 1a illustrated in FIG. 8 is in a form
having the upper ends of the two fastener stringers 2 cut off. It
is different from the slide fastener illustrated in FIG. 7 in
respect that a lower stopping part 6 is formed by fusing the
prescribed lower portions of the engaged rows of coupling elements
4.
[0054] A slide fastener 1b illustrated in FIG. 9 is different from
the slide fastener illustrated in FIG. 7 in respect that upper stop
members 7 are attached respectively to the upper ends of the rows
of coupling elements 4b attached fast to fastener tapes 3b of
fastener stringers 2b and a lower stop member 8 is attached to the
lower ends thereof.
[0055] FIG. 10 illustrates an open-link type slide fastener 1c. To
the lower end portions of fastener tapes 3c of fastener stringers
2c, reinforcing sheet-like members (taffeta) 9 are welded through
the medium of an adhesive layer (not shown). A box member 11 of a
pin-and-box separator 10 is attached to the inner edge of one of
the opposed reinforcing sheet-like members 9 and a butterfly rod or
pin 13 is attached to the inner edge of the other reinforcing
sheet-like member 9. The box member 11 is formed integrally with a
box rod 12. The reference numeral 14 denotes a core cord which is
inserted in the longitudinal direction through the empty space
inside the spiral of the coiled coupling element 4c and the
reference numeral 15 denotes a sewing thread sewing the core cord
14 and the coiled coupling element 4c along the longitudinal edge
of the fastener tape 3c.
[0056] When the sliders for varying kinds of slide fasteners as
mentioned above are formed of the fiber-reinforced thermoplastic
resin of the present invention incorporating the sliding
property-imparting agent therein, they exhibit extremely high
durability to withstand open-close reciprocations. Heretofore, the
difficulty which is encountered in the manufacture of a slider made
of synthetic resin and endowed with high strength and high wear
resistance or durability has formed the cause for defying all
attempts to form all the component parts of the slide fastener
invariably with synthetic resin. Since the present invention
permits manufacture of a slider made of synthetic resin and endowed
with high strength and high wear resistance or durability, it has
become possible to produce all the component parts of a slide
fastener invariably with synthetic resin. When such products as
clothes and bags to which such slide fasteners are attached are
discarded after use, therefore, the slide fasteners may be
recovered from the discarded products and put to reuse. This fact
contributes toward lessening the occurrence of industrial waste
and, at the same time, proves highly significant from the
standpoint of recycling waste and protecting the earth's
environment.
[0057] Now, the following examples will be cited for the purpose of
aiding in more specific description of the present invention.
EXAMPLE 1
[0058] In this example, a glass fiber-containing polybutylene
terephthalate (made by Mitsubishi Rayon Company Limited and sold
under the trademark designation of "Toughpet PBT 1101 G30", glass
fiber content: 30% by weight) was selected and used as a
reinforcing fiber-containing thermoplastic resin (raw material
1-A). Further, polytetrafluoroethylene was selected as a sliding
property-imparting agent exhibiting a storage elastic modulus in
the range of 3.5.times.10.sup.8 Pa to 5.0.times.10.sup.8 Pa in a
temperature range of 30.degree. C. to 70.degree. C. Pellets having
this agent incorporated in the glass fiber-containing polybutylene
terephthalate mentioned above at a ratio of 5% by weight (raw
material 1-B) or 10% by weight (raw material 2-C) were prepared.
First, these pellets were dried under a reduced pressure at
120.degree. C. for four hours. The dried pellets were immediately
subjected to molding with an injection molding machine to produce a
slider for a slide fastener. Thus, the sliders of the raw materials
1-A, 1-B, and 1-C. were obtained as formed articles.
[0059] The formed articles 1-A, 1-B, and 1-C were respectively
tested for durability to withstand open-close reciprocations of
slider in accordance with JIS S 3015. The reciprocating motion of
the slider had a stroke of 3 inches (76.2 mm) and a speed of 30
reciprocations per minute. The results are shown in Table 1.
[0060] As shown in Table 1, in the test for durability to withstand
open-close reciprocations of slider, the average of the numbers
found in a total of five runs of test was 4,129 in the case of the
formed article 1-B containing 5% by weight of
polytetrafluoroethylene and 980 in the case of the formed article
1-C containing 10% by weight of polytetrafluoroethylene, whereas it
was 66 in the case of the formed article 1-A containing no
polytetrafluoroethylene. The comparison of these results clearly
indicates that the averages found for the formed articles
containing polytetrafluoroethylene were far larger than that found
for the formed article containing no polytetrafluoroethylene. Thus,
the fiber-reinforced thermoplastic resin is enabled by
incorporating therein a material possessing a storage elastic
modulus in a prescribed range as a sliding property-imparting agent
in a prescribed amount to acquire notably exalted wear resistance.
When the slider as a sliding member in a slide fastener is formed
of the fiber-reinforced thermoplastic resin containing the sliding
property-imparting agent, it exhibits notably enhanced durability
to withstand the open-close reciprocations of slider.
1 TABLE 1 Durability, number of reciprocations (MH grade) Number
Formed Max- Min- of article Material Average imum imum samples 1-A
Polybutylene 66 80 57 5 terephthalate containing 30% by weight of
glass fibers 1-B Polybutylene 4129 5000* 2150 5 terephthalate
containing 30% by weight of glass fibers + 5% by weight of
polytetrafluoroethylene 1-C Polybutylene 980 3091 55 5
terephthalate containing 30% by weight of glass fibers + 10% by
weight of polytetrafluoroethylene Remark *Two samples on which the
test was discontinued after 5000 reciprocations.
EXAMPLE 2
[0061] In this example, a glass fiber-containing polyamide-based
resin (made by Mitsubishi Engineering Plastics K.K. and sold under
the trademark designation of "Reny 1022 HS", glass fiber content:
50% by weight) was selected and used as a reinforcing
fiber-containing thermoplastic resin (raw material 2-A). Further,
polytetrafluoro-ethylene was selected as a sliding
property-imparting agent exhibiting a storage elastic modulus in
the range of 3.5.times.10.sup.8 Pa to 5.0.times.10.sup.8 Pa in a
temperature range of 30.degree. C. to 70.degree. C. Pellets having
this agent incorporated in the glass fiber-containing
polyamide-based resin mentioned above at a ratio of 5% by weight
(raw material 2-B) or 7% by weight (raw material 2-C) were
prepared. Further, pellets having 10% by weight of
polytetrafluoroethylene incorporated in a glass fiber-containing
polyamide-based resin (made by Mitsubishi Engineering Plastics K.K.
and sold under the trademark designation of "Reny 1022 HS", glass
fiber content: 45% by weight) (raw material 2-D) were prepared.
These pellets were dried under a reduced pressure at 120.degree. C.
for four hours. The dried pellets were immediately subjected to
molding with an injection molding machine to produce a slider for a
slide fastener. Thus, the sliders of the raw materials 2-A, 2-B,
2-C, and 2-D were obtained as formed articles.
[0062] The formed articles 2-A, 2-B, 2-C, and 2-D were respectively
tested for durability to withstand open-close reciprocations of
slider in accordance with JIS S 3015 in the same manner as in
Example 1. The results are shown in Table 2.
[0063] As shown in Table 2, in the test for durability to withstand
open-close reciprocations of slider, the average of the numbers
found in a total of five runs of test was 1,151 in the case of the
formed article 2-B containing 5% by weight of
polytetrafluoroethylene, 2,204 in the case of the formed article
2-C containing 7% by weight of polytetrafluoroethylene, and 4,681
in the case of the formed article 2-D containing 10% by weight of
polytetrafluoroethylene, whereas it was 353 in the case of the
formed article 2-A containing no polytetrafluoroethylene. The
comparison of these results clearly indicates that the averages
found for the formed articles containing polytetrafluoroethylene
were far larger than that found for the formed article containing
no polytetrafluoroethylene. Thus, the fiber-reinforced
thermoplastic resin is enabled by incorporating therein a material
possessing a storage elastic modulus in a prescribed range as a
sliding property-imparting agent in a prescribed amount to acquire
notably exalted wear resistance. When the slider as a sliding
member in a slide fastener is formed of the fiber-reinforced
thermoplastic resin containing the sliding property-imparting
agent, it exhibits notably enhanced durability to withstand the
open-close reciprocations of slider.
2 TABLE 2 Durability, number of reciprocations (MH grade) Number
Formed of article Material Average Maximum Minimum samples 2-A
Polyamide-based resin 353 408 244 5 containing 50% by weight of
glass fibers 2-B Polyamide-based resin 1151 1845 845 5 containing
50% by weight of glass fibers + 5% by weight of
polytetrafluoroethylene 2-C Polyamide-based resin 2204 2480 2050 5
containing 50% by weight of glass fibers + 7% by weight of
polytetrafluoroethylene 2-D Polyamide-based resin 4681 4838 4551 5
containing 45% by weight of glass fibers + 10% by weight of
polytetrafluoroethylene
[0064] Since the formed article of thermoplastic resin according to
the present invention, as described above, is formed of what has
been obtained by adding a proper amount of a material exhibiting
storage elastic modulus in the range of 3.5.times.10.sup.8 Pa to
5.0.times.10.sup.8 Pa in a service temperature range of 30.degree.
C. to 70.degree. C. to a thermoplastic resin reinforced with
fibers, it retains the high strength imparted by the addition of
the reinforcing fibers and, at the same time, enjoys notable
improvement in wear resistance, and manifests the wear resistance
conspicuously particularly in the service temperature range in
which the temperature is elevated owing to the frictional heat
caused by the sliding motion of a sliding member.
[0065] The formed article of thermoplastic resin according to the
present invention, therefore, can be advantageously used as sliding
parts of varying sorts. It exhibits extremely high durability to
withstand open-close reciprocations when it is used as a slider in
a slide fastener.
[0066] While certain specific embodiments and working examples have
been disclosed herein, the invention may be embodied in other
specific forms without departing from the spirit or essential
characteristics thereof. The described embodiments and examples are
therefore to be considered in all respects as illustrative and not
restrictive, the scope of the invention being indicated by the
appended claims rather than by the foregoing description and all
changes which come within the meaning and range of equivalency of
the claims are, therefore, intended to be embraced therein.
* * * * *