U.S. patent number 3,645,819 [Application Number 04/712,778] was granted by the patent office on 1972-02-29 for method for manufacturing synthetic multicore elements.
This patent grant is currently assigned to Toray Industries, Inc.. Invention is credited to Shigeru Fujii, Takashi Miwa, Kazushige Noji, Chikatsu Okagawa, Masamichi Toki.
United States Patent |
3,645,819 |
Fujii , et al. |
February 29, 1972 |
METHOD FOR MANUFACTURING SYNTHETIC MULTICORE ELEMENTS
Abstract
A method for manufacturing improved synthetic bonded filament
yarn by forming a unit composite from matrix and island components,
assembling a plurality of the unit composites into a randomly
bundled multifilament yarn and heating the multifilament yarn at a
temperature between the melting points of both components. The
cross section of the unit composite can be obtained in any of
so-called sheath-core configuration, randomly distributed
configuration and bimetallike configuration of the components. The
bonded filament yarn has excellent flexibility and a unique surface
condition having many wrinkles thereon and the bonded filament yarn
of the present invention can be advantageously used for numerous
industrial uses such as chafer fabrics of tires, bowstrings,
fishing nets, guts of rackets, etc.
Inventors: |
Fujii; Shigeru (Nagoya-shi,
JA), Miwa; Takashi (Nagoya-shi, JA), Noji;
Kazushige (Nagoya-shi, JA), Okagawa; Chikatsu
(Nagoya-shi, JA), Toki; Masamichi (Otsu-shi,
JA) |
Assignee: |
Toray Industries, Inc. (Tokyo,
JA)
|
Family
ID: |
27548985 |
Appl.
No.: |
04/712,778 |
Filed: |
March 13, 1968 |
Foreign Application Priority Data
|
|
|
|
|
Mar 16, 1967 [JA] |
|
|
42/21483 |
May 11, 1967 [JA] |
|
|
42/38736 |
Aug 16, 1967 [JA] |
|
|
42/52169 |
Oct 26, 1967 [JA] |
|
|
42/68553 |
Oct 21, 1967 [JA] |
|
|
42/88955 |
|
Current U.S.
Class: |
156/148; 156/136;
156/167; 156/296; 152/543; 156/166; 156/180; 138/141 |
Current CPC
Class: |
B60C
9/0028 (20130101); B60C 9/0042 (20130101); A63B
51/02 (20130101); D01D 5/36 (20130101); D02G
3/402 (20130101); B60C 15/06 (20130101); Y10T
152/10828 (20150115) |
Current International
Class: |
B60C
9/00 (20060101); B60C 15/06 (20060101); D01D
5/30 (20060101); D01D 5/36 (20060101); B29b
017/32 () |
Field of
Search: |
;156/166,167,180,296
;28/73 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Padgett; Benjamin R.
Assistant Examiner: Hunt; B. H.
Claims
What is claimed is:
1. A method of manufacturing synthetic multicore filaments
comprising: providing a plurality of individual filament composites
each comprising a core component composed of synthetic polymeric
material having a given melting point temperature and a sheath
component surrounding said core component composed of synthetic
polymeric material having a melting point temperature lower than
said given melting point temperature; bundling together said
plurality of individual filament composites to form a bundle of
multifilament composites; imparting from 50 to 500 twists per meter
length to said bundle of multifilament composites; and melting the
sheath components of the twisted bundle of multifilament composites
at a temperature between the melting point temperatures of said
core and sheath components into a common matrix component
containing therein said core components whereby a multicore
filament is obtained.
2. A method according to claim 1, wherein said synthetic polymeric
materials are selected from a group consisting of polycaprolactam,
polyhexamethylene-adipamide, polyethylene terephthalate,
polypropylene, polyethylene, polyacetal, polyvinylchloride,
polystyrene, copolymer of these polymers, blended polymers of said
polymers, and block copolymers of said polymers.
3. A method according to claim 1, wherein the combination of said
sheath component and core component polymeric materials is selected
from a group consisting of sheath-forming polycaprolactam with
core-forming polyhexamethylene-adipamide and sheath-forming
polycaprolactam with core-forming polyethylene-terephthalate.
4. A method according to claim 1, wherein said melting point
temperature of said core component is higher than that of said
sheath component by at least 15.degree. C.
5. A method according to claim 4, wherein said core component is
composed of nylon 66 and said sheath component is composed of nylon
6.
6. A method according to claim 5, wherein the degrees of
polymerization of said two polymeric materials are defined by the
following formula:
P.sub.66 =0.23 P.sub.6 +51.5
P.sub.66 =0.29 P.sub.6 +28.0
150< P<300
wherein
P.sub.66 = upper limit value of degree of polymerization of nylon
66
P.sub.66 = lower limit value of degree of polymerization of nylon
66
P.sub.6 = degree of polymerization of nylon 6.
7. A method according to claim 1, wherein said heat-treating step
includes maintaining said twisted bundle of multifilament
composites free of slack during their heat treatment.
8. A method according to claim 1 including heat-treating said
twisted bundle of multifilament composites at a low enough
temperature to develop a plurality of air pockets in said common
matrix component to effectively increase the flexibility of the
multicore filament.
9. A method according to claim 1 further including weaving a
plurality of said multicore filaments into a tubeless tire chafer
strip.
10. A method of manufacturing a tubeless tire reinforcing chafer
strip composed of synthetic multicore filaments comprising:
providing a plurality of individual filament composites each
comprising a core component composed of synthetic polymeric
material having a given melting point temperature and a sheath
component surrounding said core component composed of synthetic
polymeric material having a melting point temperature lower than
said given melting point temperature; bundling together said
plurality of individual filament composites to form a bundle of
multifilament composites; imparting from 50 to 500 twists per meter
length to said bundle of multifilament composites; weaving a
plurality of such bundles of multifilament composites into a chafer
strip configuration; and heat-treating said chafer strip at a
temperature between the melting point temperatures of said core and
sheath components for a sufficient time to effect melting of
individual ones of said sheath components of each twisted bundle
into a common matrix component containing therein said core
components.
11. A method according to claim 10 including, prior to said
heat-treating step, disposing said chafer strip within a tubeless
tire; and wherein said heat-treating step is carried out during
vulcanization of said tubeless tire.
12. A method of manufacturing synthetic multicore filaments
comprising: providing a plurality of bundles of filaments wherein
each bundle comprises a first plurality of filaments composed of
synthetic polymeric material having a given melting point
temperature and a second plurality of core filaments composed of
synthetic polymeric material having a melting point temperature
lower than said given melting point temperature randomly
interspersed with said first plurality of filaments; twisting
together said plurality of bundles of filaments to obtain a
multifilament composite; and heat-treating said multifilament
composite at a temperature between the melting point temperatures
of said first and second pluralities of filaments for a sufficient
time to effect melting of said second plurality of filaments into a
common matrix component containing uniformly dispersed therein said
core filaments.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing
improved bonded filament yarn and more particularly relates to a
method for manufacturing bonded filament yarn composed of a matrix
component and a plurality of island components which is
particularly used for industrial use such as chafer fabric of
tires, manufactured synthetic filament yarn and industrial products
produced of it.
Remarkable inroads have been made by synthetic fibers, both in the
form of filament yarns and spun yarns, into the field of industrial
use, particularly into the field of reinforcements for various
types of tires. For instance, they have been favorably used for the
carcass portion of a tire in a form of tire cords, for the chafing
strip portion or for the cushion portion of a tire in the form of a
woven cloth.
However, such application of conventional synthetic fibers for
reinforcement of tires was accompanied by several drawbacks due to
the configurational characteristics of fibers used in the
reinforcement. As is well known, the conventional synthetic tire
cord was made of a twisted multifilament yarn or a twisted bundle
of spun yarns. When such a tire cord is immersed into dirty water,
which usually happens with a tire, dirts in the water are easily
soaked into the configuration of the tire cord together with water
on account of capillarity due to the presence of a plurality of
fine filaments or fibers in the yarn and is left there after the
water has evaporated. Consequently, this often caused quick and
easy contamination of the tire cord. This is the first defect of
the tire cord made of the conventional synthetic yarns.
When such synthetic multifilament yarn is used for the chafing
strip of a tubeless tire, this capillarity due to the presence of a
plurality of fine filaments or fibers in the yarn also causes
leakage of air contained within the tire through the multifilament
yarn positioned in the bead portion of the tire. Such leakage of
air is liable to cause quick lowering of internal pressure of the
tire and easy formation of spots within the carcass portion of the
tire, both of which often result in unexpected accident when the
car is running.
When such synthetic reinforcing member is used for the chafing
strip portion of a tire, it is subjected to severe friction and
repeating impact, which is usually the case with a tire, resulting
in separation and breakage of the component fibers or filaments.
This separation and breakage of the component fibers and filaments
causes quick deterioration of the bead portion of the tire and
finally quick wearing-out of the tire. This is the defect of the
chafer fabric made of the conventional synthetic yarns.
In order to avoid such troubles encountered in the conventional
synthetic chafer fabric of a tire, several methods have been
proposed. Use of bonded filament yarns instead of multifilament
yarns or spun yarn is one of method for eliminating troubles due to
capillarity. However chafer fabric made of a bonded filament yarn
could not be provided with good flexibility. Moreover, when a cloth
for chafer is made of bonded filament yarns, the thickness at the
intersection of the component bonded filament yarns becomes larger
than the other portions, which is theoretically twice as thick as
that of the other portions and the concentration of stress upon
these thickened intersections causes quick wearing-out of the
netted cloth starting from these intersections. Besides, there
often has been observed unfavorable irregular arrangement of yarns
in the construction of the cloth made of bonded filament yarns
caused by slippage of yarn having smooth surface. Application of
resin finishing upon the multifilament cloth for chafer is another
example of an attempt to prevent leakage of air. But, this resin
treatment has two drawbacks, the first of these is that it is
difficult for the resin solution to penetrate into the
multifilament and the second is the separation of resins from the
filaments in the cloth during actual use of the cloth.
As is well-known, polyamide filament yarn has been favorably used
as a material for industrial use such as tire cords or
reinforcements for tires. Conventionally, manufacture of highly
oriented polyamide bonded filament was performed by extruding
molten polyamide polymer through fine holes of a spinneret,
instantaneously cooling the extruded filaments with a cooling
medium such as water and applying stretching operation upon the
cooled filaments while taking up onto a package. In case stretched
filaments of higher than 40 denier was required, which is generally
the case when used as a material for industrial use, it was
necessary to use water as the cooling medium in order to obtain
good result in the stretching process. However, in case of the
water cooling system, the spinning speed of the filament years was
limited to from 30 to 50 meters/min. and further limited to lower
than 30 meters/min. in case the stretched bonded filament yarn of
larger denier was required. This is mainly because of the fact that
an overstretching of the filaments takes place due to the flow
resistance of the cooling water when the filaments are passed
through the water bath at a high-processing speed. Consequently, it
was very much difficult to obtain a stretched filament yarn of
larger denier by processing the filament at a spinning speed the
same as that of the usual melt-spinning process, that is at a
spinning speed from 300 to 1,000 meters/min. Moreover, it was
difficult to obtain good orientation and crystallization of the
material polymer by the usual stretching process when the stretched
filament of larger denier is required, and such poor orientation
and crystallization of the material polymer upon stretching
resulted in lowered strength of the manufactured bonded filament,
which usually ranged between 5 and 6 g./denier.
The principal object of the present invention is to provide an
improved synthetic bonded filament yarn provided with good
flexibility, with high strength, and resistance against impact
loading, chemicals, mildew, aging and damage by wetting.
Another object of the present invention is to provide an improved
synthetic filament yarn particularly used for industrial use such
as reinforcement of a tire bead provided with good flexibility of
the synthetic multifilament yarn or synthetic spun yarn
conventionally used for the same purpose while eliminating the
drawbacks encountered in these conventional synthetic yarns.
A still further object of the present invention is to provide an
improved method for making synthetic reinforcing cloth for tires
which can withstand long use and repeated impact loading by
effectively preventing the concentration of stress upon the
intersections of the component filament yarns and the slippage of
yarns in the construction of the cloth.
A still further object of the present invention is to provide a
novel method for manufacturing a synthetic filament yarn of larger
denier provided with high orientation and crystallization of the
material polymers.
A still further object of the present invention is to provide an
economical method for manufacturing a synthetic bonded filament
yarn having high strength at a high-production speed almost equal
to that of the conventional melt-spinning process.
In accordance with the above-described objects of the invention,
the method of the present invention is characterized by forming a
unit composite from at least one kind of an island or core
component and at least one kind of a matrix component whose melting
point is different from that of the island component, assembling a
plurality of the unit composites thus formed into a bundle and
melting the matrix component of all unit composites by heating.
The synthetic filament yarn manufactured by the method of the
present invention is characterized by having a cross-sectional
profile composed of mutually continuous matrix portion and a
plurality of island portions almost uniformly distributed within
the matrix portion.
In the following explanation of the present invention, the
description will be made mainly by referring to the case of
polyamide polymer as the material for the synthetic filament yarn
of the present invention because of the fact that the polyamide
filament yarn is generally and favorably used as a material for
industrial use such as in a tire. However, the polymer material
used for the purpose of the present invention can also be chosen,
in accordance with the requirements of the end use, from a group
composed of polycaprolactam, polyhexamethylene-adipoamide,
polyethylene terephthalate, polypropylene, polyethylene,
polyacetal, polyvinyl chloride, polystyrene, copolymers of these
polymers, blended polymers of these polymers and blocked polymers
of these polymers.
With respect to the combination of these material polymers, the
combination of polyhexamethylene-adipoamide as the island component
with polycaprolactam as the matrix component or the combination of
polyethylene terephthalate as the island component with
polycaprolactam as the matrix are preferably for the purpose of the
present invention.
The cross-sectional profile of the unit composite of the present
invention is characterized by being composed of at least one kind
of an island component and at least one kind of a matrix
component.
One typical example of the unit composite is obtained in the form
of a sheath-core configuration wherein the island component is
positioned in the core portion and the matrix component is
positioned in the sheath portion surrounding the core portion in a
substantially concentric arrangement. Another example of the unit
composite is obtained in a form of a multifilament yarn which
contains a plurality of fine island component filaments and a
plurality of fine matrix component filaments in a randomly bundled
condition. In some cases, it is also possible to have both
components in a so-called bimetallike configuration within the
cross section of the unit composite.
Further features and advantages of the present invention will be
apparent from the ensuing description with reference to the
accompanying drawings to which, however, the scope of invention is
in no way limited.
FIGS. 1A and 1B are diagrammatical cross-sectional view of an
embodiment of a unit composite having so-called sheath-core
configuration,
FIG. 2 is a diagrammatical cross-sectional view of a bonded
filament yarn of the present invention,
FIGS. 3A and 3B are side views of a conventional bonded filament
yarn and a bonded filament yarn manufactured by the method of the
present invention, respectively,
FIG. 4 is a graphical representation of the relation between the
degree of polymerizations of nylon 6 and nylon 66 which can be used
favorably in the method of the present invention,
FIG. 5 is a diagrammatical cross-sectional view of another
embodiment of a unit composite having the so-called
multifilamentlike configuration,
FIG. 6 is a diagrammatical cross-sectional view of a bonded
filament yarn made of a plurality of unit composites shown in FIG.
5,
FIG. 7 is a cross-sectional view of a tubeless tire wherein a
reinforcing cloth made of the bonded filament yarns of the present
invention is used.
UNIT COMPOSITE OF SHEATH-CORE CONFIGURATION;
ITS MECHANISM, MANUFACTURE, UTILIZATION
AND EXAMPLES.
As mentioned above, one typical example of the unit composite of
the present invention is obtained by putting the island and matrix
components in a sheath-core arrangement wherein the island
component is completely surrounded by the matrix component in a
substantially concentric condition.
The manufacturing method of the polyamide bonded filament yarn
composed of this type of unit composite is characterized by
composite spinning the polyamide sheath component of lower melting
point together with the polyamide core component, whose melting
point is at least 15.degree. C. higher than that of the sheath
component, through a spinneret, stretching the composite filaments
thus obtained, doubling a plurality of the stretched filaments into
a bundle of filaments and heating the bundle of filaments at a
heating temperature which is higher than the melting point of the
sheath component and lower than that of the core component, thereby
melting the sheath components of each composite filament and
converting the bundle of the composite filaments into a bonded
filament whose cross section is composed of mutually continuous
matrix portion which is made of the sheath components and a
plurality of island portions which are made of the core components
almost uniformly distributed within the matrix portion.
In the above-mentioned procedure, the cross-sectional profile of
the unit composite can be obtained both in a concentric arrangement
and in an eccentric arrangement. Both of the arrangements can be
employed suitably for the purpose of the present invention in so
far as the core component is completely surrounded by the sheath
component.
The composite spinning of this type of composite filament is
carried out, for example, by melting both of the component polymers
independently using the respective melting apparatus and extruding
both of the molten polymers simultaneously through the same
spinneret especially designed for sheath-core composite
spinning.
The formation of a bonded filament yarn from a bundle of composite
filaments is generally performed by heating the bundle of composite
filaments just after stretching and doubling as above described.
However, in special cases, heat treatment can also be applied to
the textile products made of them, thereby melting the sheath
components contained in the multifilament yarns forming the cloth
or the screen sheet. Moreover, for the purpose of uniform melting
of the sheath components contained in the multifilament yarn, it is
also recommended that twists from 50 turns/meter to 500 turns/meter
be applied to the multifilament yarn prior to heat treatment.
The heating temperature employed in this heat treatment should be
adjusted according to the degree of flexibility required for the
manufactured bonded filament yarn. In case a high degree of
flexibility is required for the manufactured bonded filament yarn,
it is desirable to form numerous air cells in the structure of the
bonded filament yarn by heating the multifilament yarn at a
relatively low temperature.
As the heating medium used for the heat treatment of the present
invention, any one of such mediums as heated air, heated inert gas,
highly pressurized steam and superheated steam can be favorably
used, while in some special case, a chemical medium such as a
polyamide solvent can also be used. In case a dry medium such as
heated air is used, the temperature of the heating medium must
generally be maintained higher than the melting point of the sheath
polyamide polymer. While in case of wet heating, the heating
temperature should be higher than the temperature 80.degree. C.
below the melting point of the sheath polyamide polymer. For
example, when the melting point of the sheath polyamide polymer is
210.degree. C., it is possible to melt the sheath polyamide polymer
by using a high-pressured steam maintained at a temperature higher
than 130.degree. C. As a special case, when a roughened surface
condition is required for the manufactured bonded filament yarn, a
chemical medium such as heated phenol solution can be effectively
utilized. This kind of chemical heating medium is favorably used
especially when a polyamide copolymer is used as the sheath
component.
As to the material polymer used for both of the components, the
method of the present invention is characterized by using the same
kind of polymers in order to obtain a stronger coherency between
components after heating and transparency of the manufactured
bonded filament yarn. The use of different kind of polymers for
respective component will be accompanied by poor coherency and
lower transparency. However, by the requirement of the end use, the
bonded filament yarn of the present invention can contain
delustering agents such as titanium dioxide, light-resisting agents
such as a manganate or copper salt, optical bleaching agents and
heat-resisting agents such as copper iodide, copper chloride,
copper bromide, copper benzoate and copper acetate.
When deciding the difference in the melting point of both component
polyamide polymers, it should be noted that the component polyamide
polymer with the higher melting point should not be damaged by the
heat treatment for melting the component polyamide polymer with the
lower melting point, that is, the difference in the melting point
should be more than at least 15.degree. C., and more preferably
more than 25.degree. C. However there is an upper limit in the
difference. The difference in the melting point is dependent upon
the combination of component polymers. In case the manufactured
bonded filament yarn is used as a material for a brush for cleaning
at a high temperature, it is necessary to select a sheath component
polymer having relatively high-melting point. While in case the
heat treatment is applied to manufactured bonded filament yarn for
the purpose of improving the heat-shrinking property, it is
necessary to select a sheath component polymer whose melting point
does not differ too much from the processing temperature of the
heat treatment for the sake of easiness in the actual production
process. Consequently, it can be concluded that the melting point
of the sheath component polyamide polymer should preferably be
higher than at least 160.degree. C. in accordance with the purpose
of the present invention.
With respect to the content of both components within the
manufactured bonded filament yarn, it is desirable that the sheath
component should be more than 10 percent by weight, more preferably
the content of the sheath component should range between 20 and 40
percent by weight. Also, the content of the core component should
be less than 90 percent by weight, more preferably it should range
between 60 and 80 percent by weight. However, in case high strength
is particularly required for the manufactured bonded filament yarn,
it is desirable to make the content of the sheath component
smaller.
The thickness of the unit composite filament of the present
invention ranges between 2 and 30 denier, and more preferably
between 5 and 15 denier. After being extruded through the
spinneret, a plurality of those unit composite filaments are
bundled together in the form of a multifilament yarn and, if
necessary, twisted. The number of the unit composite filaments
contained within a multifilament yarn is determined according to
the requirement of the end use, for instance, it is obtained as a
multifilament of 420 denier containing 40 filaments, 840 denier
containing 80 filaments or 840 denier containing 96 filaments.
The sheath component polyamide polymer used in the present
invention can favorably be chosen from a group composed of
poly-.epsilon.-caproamide (nylon 6), polycaprylicamide (nylon 8),
polyundecanoamide (nylon 11), polydodecanoamide (nylon 12),
polyhexamethylene-cebacamide (nylon 610), polyamide copolymer of
.epsilon.-caprolactum with hexamethylene-diammonium-adipate (nylon
6/66 66), polyamide copolymer of .epsilon.-caprolactum with
hexamethylene-diammonium-isophthalate (nylon 6/6I), polyamide
copolymer of .epsilon.-caprolactum with
hexamethylene-diammonium-terephthalate (nylon 6/6T), polyamide
copolymer of .epsilon.-caprolactum with
hexamethylene-diammonium-cebacate (nylon 6/610), polyamide
copolymer composed of any three of .epsilon.-caprolactum,
hexamethylene-diammonium-adipate,
hexamethylene-diammonium-cebacate,
hexamethylene-diammonium-isophthalate and
hexamethylene-diammonium-terephthalate (for instance nylon
6/66/610). The composition of the sheath component polyamide
copolymer can be changed as required in accordance with the melting
point of the core component polyamide polymer combined with it.
As to the core component polymer, .epsilon.-caproamide and
polyhexamethylene-adipamide can favorably be used, however any
other polyamide polymers can be used without departing from the
purpose of the present invention in accordance with the combination
of the components.
Favorable combinations of both components can be obtained, for
instance, by combining nylon 6 as the sheath with nylon 66 as the
core, copolymerized nylon 6/nylon 66 as the sheath with nylon 6 as
the core, copolymerized nylon 66/nylon 6 as the sheath with nylon
66 as the core, nylon 12 as the sheath with nylon 6 as the core,
nylon 11 as the sheath with nylon 6 as the core, nylon 11 as the
sheath with nylon 66 as the core, nylon 12 as the sheath with nylon
66 as the core, nylon 610 as the sheath with nylon 66 as the core
and copolymerized nylon 66/nylon 610 as the sheath with nylon 66 as
the core.
Referring to FIG. 1A, a cross section of an embodiment of the unit
composite of the present invention is diagrammatically shown. In
this embodiment, the cross section of the unit filament composite 1
is composed of a core component 2 and a sheath component 3
surrounding the core component 2 in a concentric arrangement.
Another embodiment of the cross section is shown in FIG. 1B,
wherein both of the components 2 and 3 are arranged in an eccentric
arrangement. The bonded filament yarn of the present invention can
be obtained by heating a bundle of a plurality of such unit
composite filaments, thereby melting the sheath component of all
unit composite filaments. By melting the sheath component of all
unit composite, all of the sheath components adhere mutually to
form a continued matrix component of the manufactured bonded
filament yarn, as shown in FIG. 2, wherein the core components 2
are positioned within the matrix component 4 in an uniformly
distributed condition.
In FIG. 3A, a photographical representation of a side view of the
conventional polyamide bonded filament yarn is shown, while in FIG.
3B, a photographical representation of a side view of a polyamide
bonded filament yarn of the present invention is shown. As is
clearly shown in the drawing of FIG. 3A, the conventional polyamide
bonded filament yarn is provided with a smooth surface due to a
substantially circular cross-sectional profile. However, usually,
there is little demand for bonded filament yarns having such smooth
surface, that is, in most cases, it is required to positively
roughen the surface of the bonded filament yarn for the purpose of
the prevention of yarn slippage within the structure of a product
made of them, such as a fishing net or a gut of a tennis racket.
The bonded filament yarn of the present invention differs from such
a conventional bonded filament yarn as it is provided with a rough
surface during its manufacture due to noncircular cross-sectional
profile as clearly shown in FIGS. 2 and 3B. This is one of the
outstanding features of the bonded filament yarn manufactured by
the method of the present invention.
As the bonded filament yarn of the present invention is provided
with such a rough surface, it can be used suitably even for fishing
lines, guts of rackets, fasteners, screens, belts and bristles, for
which the conventional bonded filament yarns could not be used on
account of their smooth surface condition.
The following examples are illustrative of the present invention,
but are not to be construed as limiting the same.
EXAMPLE 1
Nylon 6 having a relative viscosity of 2.7 and nylon 66 having a
relative viscosity of 2.75, both with respect to 1 percent solution
of 98% sulfuric acid, were used as the material polyamide polymers.
Chips of both material polymers were dried at 110.degree. C. for 18
hours and melted independently by heating at 285.degree. C. Molten
polymer of nylon 6 was supplied to a spinneret at a feeding rate of
43 g./min. while molten polymer of nylon 66 was also supplied to
the spinneret but at a feeding rate of 100 g./min. The spinneret
was provided with 80 spinning holes. After being extruded through
the spinneret, the multifilament yarn, which is composed of 30
percent by weight of nylon 6 and 70 percent by weight of nylon 66,
was taken up at a processing speed of 300 meters/min. Then the
multifilament yarn was stretched at a stretching ration of 5.2
while being subjected to heat treatment by a heating member
maintained at 180.degree. C. and converted into a bonded filament
yarn of the present invention. The stretched bonded filament yarn
of 860 denier thus obtained was provided with a breaking strength
of 8.2 g./denier and a breaking elongation of 18.6 percent.
COMPARATIVE EXAMPLE 1
Nylon 66 having a relative viscosity of 2.75 with respect to
sulfuric acid was melted at 285.degree. C. The molten polymer was
extruded through a spinneret at a spinning rate of 33 g./min. in
the form of a bonded filament yarn and was cooled by with water at
a position 10 cm. under the spinneret. After taking up at a
processing speed of 35 meters/min., the bonded filament yarn was
stretched at a stretching ratio of 4.5 in hot water maintained at
60.degree. C. The stretched bonded filament yarn of 900 denier thus
obtained was provided with a breaking strength of 5.1 g./denier and
a breaking elongation of 20.4 percent.
EXAMPLE 2
Nylon 12 having a relative viscosity of 2.0 and nylon 6 having a
relative viscosity of 2.4 both with respect to sulfuric acid were
used as the material polyamide polymers. Chips of both material
polymers were melted independently by heating at 250.degree. C. and
were extruded through a spinneret in the form of a plurality of
unit composite filaments of sheath-core configuration. After taking
up at a processing speed of 400 meters/min., the multifilament
yarn, which is composed of 20 percent by weight of nylon 12 and 80
percent by weight of nylon 6, was stretched at a stretching ratio
of 4.2 without heating. The stretched multifilament yarn of 880
denier/80 filaments thus obtained was provided with a breaking
strength of 6.5 g./denier and breaking elongation of 26.1
percent.
EXAMPLE 3
A polyamide copolymer (nylon 6/nylon 66) obtained by
copolymerization reaction carried out at a temperature of
257.degree. C. for 19 hours under pressure from a solution composed
of 15 percent by weight of hexamethylene-diammonium-adipate and 85
percent by weight of .epsilon.-caprolactum. The relative viscosity
of the polyamide copolymer obtained was 3.0 with respect to
sulfuric acid and the melting point measured by the optical method
was 198.degree. C. Nylon 6 polymer having a relative viscosity of
2.8 and a optical melting point of 220.degree. C. was obtained as
the result of polymerization of .epsilon.-caprolactum. The optical
melting point herein used was obtained by exposing a piece of the
specimen polymer to polarized light, heating the specimen at a
heating rate of 1.degree. C./min. while immersing in silicone in
order to prevent oxidation of the specimen polymer by heating, and
measuring the temperature when the luminous aspect of the specimen
has disappeared. Then the polymers obtained were melted
independently by heating at 270.degree. C. and extruded through a
spinneret designed for sheath-core composite spinning. The
resulting content of nylon 6 polymer was of 75 percent by weight
and 25 percent was for nylon 6/nylon 66 copolymer, and the
cross-sectional profile of the obtained unit composite filament
yarn was a slightly eccentric arrangement. After being taken up at
a processing speed of 500 meters/min., the multifilament yarn was
stretched at a stretching ratio of 4.6 while heating with a heating
member maintained at 180.degree. C. The stretched filament yarn of
600 denier/40 filaments thus obtained was provided with a breaking
strength of 7.6 g./denier and a breaking elongation of 24.8
percent.
EXAMPLE 4
Chips of nylon 6 and nylon 66 were prepared in the same manner as
in Example 1 with the only exception that copper benzoate was added
to both polymer chips so that the content of copper in the polymer
was 100 p.p.m. After composite spinning followed by stretching
while heating in the same manner as in Example 1, the stretched
filament yarn of 860 denier/80 filaments thus obtained was provided
with a breaking strength of 8.1 g./denier and a breaking elongation
of 19.0 percent.
EXAMPLE 5
After obtaining a multifilament yarn composed of nylon 6 and nylon
66 in the same manner as in Example 1, 200 turns/meter of S-twists
were imparted to the multifilament yarn. Next, the twisted
multifilament yarn was heated in a heating chamber maintained at
230.degree..+-. 5.degree. C. for 45 seconds without stretching,
thereby the nylon 6 sheath components of all the unit composite
filament were melted completely and a bonded filament yarn as shown
in FIG. 3B was obtained. The bonded filament yarn obtained having
an apparent thickness of 920 denier was provided with a breaking
strength of 5.7 g./denier and a breaking elongation of 18.5
percent. A plurality of wrinkles were observed on the surface of
the bonded filament yarn obtained and resembled the surface of a
multifilament yarn made of nylon 66 only. As an example of actual
utilization, a fishing line made of the bonded filament yarn of the
present example was provided with stronger knot-strength than a
fishing line made of a bonded filament yarn manufactured by the
conventional method.
EXAMPLE 6
After obtaining a multifilament yarn composed of nylon 12 and nylon
6 in the same manner as in Example 2, 100 turns/meter of S-twists
were imparted to the multifilament yarn. Next, the twisted
multifilament yarn was subjected to continuous heating in hot air
maintained at 200.degree..+-. 5.degree. C. for 30 seconds while
being stretched 2 percent, and was taken up at a processing speed
of 50 meters/min. The bonded filament yarn of 900 denier thus
obtained was provided with a breaking strength of 5.2 g./denier,
breaking elongation of 22.6 percent and had excellent transparency.
As an example of actual utilization, a bristle brush made of the
bonded filament yarns of the present example was had with excellent
flexibility and high degree of resilience, and it was confirmed
that such a brush was especially suitable for painting on account
of good conformity to paints.
EXAMPLE 7
After obtaining a multifilament yarn composed of copolymerized
nylon 6/nylon 66 and nylon 6 in the same manner as in Example 3,
200 turns/meter of primary Z-twists were imparted to the
multifilament yarn. Then, two of the primarily twisted
multifilament yarns were doubled and again imparted 200 turns/meter
of secondary S-twists. A bonded filament yarn was obtained by
heating the twisted multifilament yarn with saturated steam
maintained at 130.degree. C. for 1 second. The bonded filament yarn
of 1,300 denier thus obtained was provided with a breaking strength
of 5.3 g./denier and a breaking elongation of 20.0 percent. The
density of the bonded filament yarn obtained was 1.130 while that
of the unstretched multifilament yarn was 1.142. By comparing the
densities, it was inferred that the bonded filament yarn obtained
contained some air cells.
EXAMPLE 8
After obtaining a multifilament yarn composed of nylon 6 and nylon
66 in the same manner as in Example 4, 200 turns/meter of S-twists
were imparted to the multifilament yarn. After heating in hot air
of 220.degree. C., the bonded filament yarns obtained by heating
were woven into a woven-cloth of plain weave having a weaving
density of 7 yarns/cm. Then the woven-cloth was again subjected to
heating at 230.degree. C. for 45 seconds without stretching. The
fishing net obtained was provided with firmly melt-fixed
intersections of component bonded filament yarns, resulting in less
slippage of yarns in the net construction during actual use.
EXAMPLE 9
A plurality of unit composite filaments, which are composed of
nylon 6 as the sheath components and nylon 66 or polyethylene
terephthalate as the core components, were bundled and heated in
order to form a bonded filament yarn. The bonded filament yarns
obtained were suitable as material of the reinforcing cloth used
for the chafing strip portion of a tire. As a result of the
application of the bonded filament of the present invention,
effective prevention of lowering of the inner pressure of the tire
due to leakage of air could be attained, together with excellent
flexibility of the reinforcing cloth.
EXAMPLE 10
A bonded filament yarn of the present invention was obtained in the
same manner as in Example 9. The bonded filament yarns obtained
were suitable as material of the reinforcing member of a V-belt. By
using the bonded filament yarn of the present invention, the side
portion of the V-belt was so effectively reinforced that it could
withstand severe and frequent contact with a pulley, while a V-belt
reinforced with the conventional multifilament yarns was easily
damaged by severe and frequent contact with a pulley on account of
the separation and breakage of individual filaments within the
yarn. Beside, the reinforcing member made of the bonded filament
yarn of the present invention could easily be bonded to the rubber
portion of the belt only by using such a bonding agent as RFL
because the outer surface of the bonded filament yarn of the
present invention was completely covered with nylon 6. This is one
of the outstanding features of the bonded filament yarn of the
present invention in case it is used as a reinforcing member of
articles made of rubber.
EXAMPLE 11
A bonded filament yarn of the present invention composed of
polyethylene terephthalate as the island components and
polycaprolactum as the matrix component was used for a bowstring.
The bowstring obtained was used for a long times with less
formation of fluffs due to the breakage of component filaments and
with less contamination by dirts, and such mechanical properties of
the bowstring as stress-strain property were almost the same with
those of a bowstring made of the conventional polyethylene
terephthalate multifilament yarn.
COMPARATIVE EXAMPLE 2
Nylon 6 having a relative viscosity of 3.0 with respect to sulfuric
acid was melted at 285.degree. C. The molten polymer solution was
extruded through a spinneret at a spinning rate of 50 g./min. in
the form of a bonded filament and was cooled with water at a
position 10 cm. under the spinneret. After taking up at a
processing speed of 33 meters/min., the bonded filament yarn was
stretched at a stretching ratio of 4.5 within hot water maintained
at 65.degree. C. and, next, heated at 170.degree. C. for 30 second
while bestowing 12 percent relaxation to the processing bonded
filament yarn. The bonded filament yarn of 1,320 denier thus
obtained was provided with a breaking strength of 4.5 g./denier and
a breaking elongation of 35.2 percent.
The following examples are illustrative of the actual utilizations
of the filament yarn of the present invention, but are not to be
construed as limiting the same.
EXAMPLE 12
Bonded filament yarns of the present invention composed of nylon 66
as the island components and nylon 6 as the matrix component was
used for a gut of a racket. The gut obtained was provided with
better flexibility and higher strength than the gut made of the
conventional bonded filament yarn, together with moderate
elongation and resilience.
DEFINITION OF DEGREE OF POLYMERIZATION
OF POLYAMIDE POLYMERS USED IN THE
PRESENT INVENTION
In the manufacture of the unit composite filament of the present
invention having so-called sheath-core configuration, the condition
of the sheath-core configuration of the unit composite filament
obtained is dependent upon the difference in viscosity of the
material polymers used for both components. In case the difference
in viscosity is too large, the spinning condition will be
considerably disturbed and it becomes difficult to obtain a stable
and refined sheath-core configuration of the unit composite
filament manufactured. The formation of such a disturbed
sheath-core configuration can be effectively prevented by making
the viscosities of both of the molten polymers substantially equal
at the spinning temperature. After repeated researches, the
inventors of the present invention have reached a conclusion that
adjustment of viscosity of polymers can be attained satisfactorily
by adjusting the degree of polymerization (hereinafter abbreviated
as DP.) of polymers. In the following description, reference will
be made mainly to a case wherein nylon 6 is used as the sheath
component and nylon 66 is used as the core component of a unit
composite filament of the present invention.
In accordance with the above-described purpose of the present
invention, DP. of polymers used in the present invention should
preferably be defined by the following equations;
P.sub.66 =0.23 P.sub.6 +51.5
P.sub.66 =0.29 P.sub.6 +28.0
150< P.sub.6 <300
where P.sub.66 = Upper limit of DP. of nylon 66 core component
polymer
P.sub.66 = Lower limit of DP. of nylon 66 core component
polymer
P.sub.6 = DP. of nylon 6 sheath component polymer
In the above equations, DP. of the polymers is given in the form of
number average degree of polymerization which is generally
estimated by end-group measurement. However, the following method
can be favorably employed instead in the present invention, that
is, DP. of polymers can be calculated from the following equation,
wherein .eta..sub.r is relative viscosity of the specimen polymer
with respect to 1 percent solution of 98 percent sulfuric acid.
P.sub.6 =100 (.eta..sub.r -1.05)
P.sub.66 =50 (.eta..sub.r -1.05)
DP. of the component polymers used in the present invention refers
to DP. of a multifilament yarn after extrusion from a spinneret of
a melt spinning machine and just before being subjected to heating.
In case DP. of the polymer chip is given, it must be noted that DP.
of the polymer chip is changed while it is passing through the melt
spinning machine, depending upon the spinning temperature and the
processing time. Consequently, a suitable adjustment of the DP. is
necessary in this case. For instance, when nylon polymer having an
approximately equal quantity of amino-end groups and carboxyl-end
groups is processed at a spinning temperature of 280.degree. C.,
the relative viscosity .eta..sub.r of the nylon multifilament yarn
obtained changes as follows depending upon the length of the
processing time t, provided that t is not longer than 30
minutes.
.eta..sub.r =.eta..sub.ro +0.013 t
where .eta..sub.ro = viscosity of nylon polymer when t = 0
By defining DP. of the component polymers as above-described, it
becomes possible to apply the same spinning temperature to both of
the component polymers which makes the mechanical construction of
the melt spinning machine simple. This is one of the outstanding
features of the above-described definition of DP. of the component
polymers.
Generally, when a filament yarn of the conventional type is
composed of two components of different material polymers, the
behavior of the two components during stretching is different. In
other words, each of the components has its own optimum stretching
condition and thus, it is difficult or almost impossible for such a
filament yarn to be stretched under an optimum stretching
condition, that is, it is quite difficult to find a stretching
condition which is suitable for both of the components. Such
difficulties in stretching often results in lower strength of the
filament yarn manufactured. However, by applying the method of the
present invention, both component polymers can be processed under
an approximately identical processing condition within the melt
spinning machine and this results in almost similar behavior of
both component during stretching. Consequently it becomes possible
to obtain a filament yarn whose core component (nylon 66) is highly
oriented by stretching. This is another outstanding features of the
above-described definition of DP. of the component polymers.
Moreover, the manufacture of the bonded filament yarn by heating
the multifilament yarn can proceed at a processing speed from 300
to 500 meters/min. Such a high-production speed of the process of
the present invention assures high-production efficiency in the
production of bonded filament yarn particularly used for industrial
use. This is still other outstanding features of the above
described definition of DP. of the component polymers.
The following examples are illustrative of the effect resulting
from the definition of DP. of the component polymers.
EXAMPLE 13
Sheath-core-type unit composite filaments were produced by a
composite melt spinning machine having two independent heat
plate-type melting devices, gear pumps and a common spinneret for
composite spinning. Using acetic acid as a viscose stabilizer, a
variety of poly-.epsilon.-caproamide (nylon 6) and
polyhexamethylene-adipamide (nylon 66) having different viscosities
was obtained. Polymerization of nylon 6 was carried out under
atmospheric pressure, while polymerization of nylon 66 was carried
out under a pressure of 7.5 kg./cm..sup.2 . The spinning
temperature was adjusted in accordance with DP. of nylon 6, that
is, the spinning temperature of 280.degree. C. was used for P.sub.6
<180, 290.degree. for 180.ltoreq. P.sub.6 < 220 and
300.degree. C. for P.sub.6 .gtoreq.220. It was confirmed that the
spinning condition was not affected very much by the fluctuation of
the spinning temperature if it is less than .+-. 10.degree. C. A
multifilament yarn of 1,000 denier/24 filaments, which is composed
of 30 percent by weight of nylon 6 and 70 percent by weight of
nylon 66, was manufactured at a spinning speed of 400 meters/min.
by extruding the material molten polymers through a spinneret
designed for composite spinning and which is provided with a
plurality of spinning holes of 1.0 mm. diameter and intervening
distance of 0.5 mm. Then the multifilament yarn obtained was
stretched at a stretching ratio from 4.8 to 5.0 while heating with
a heating plate maintained at 180.degree. C. The cross-sectional
condition of the obtained bonded filament yarn is given in Table 1
and FIG. 4 for a series of combinations of material polymers,
wherein the symbol (.omicron.) represents a substantially
concentric arrangement of the cross section, the symbol (.chi.)
represents a random arrangement of the cross section and the symbol
(.DELTA.) represent an intermediate arrangement of the cross
section.
---------------------------------------------------------------------------
TABLE 1
p.sub.66 78 85 90 101
__________________________________________________________________________
p.sub.6 162 .omicron. .omicron. .DELTA. .chi. 185 .DELTA. .omicron.
.omicron. .chi. 201 .chi. .DELTA. .omicron. .DELTA. 230 -- .chi.
.chi. .omicron.
__________________________________________________________________________
the stress-strain property of the bonded filament yarn obtained is
shown in Table 2 for some typical combinations of polymers shown in
Table 1.
---------------------------------------------------------------------------
TABLE 2
breaking Breaking strength elongation P.sub.6 P.sub.66 in g./denier
in %
__________________________________________________________________________
162 78 7.6 22.5 185 78 7.5 20.8 201 78 7.0 25.3 162 90 7.7 22.6 185
90 8.3 18.5 201 90 8.4 19.1 230 90 7.5 23.1
__________________________________________________________________________
As a result of an experiment, it was confirmed that poor
arrangement of the cross section of the bonded filament yarn
manufactured often results in poor stress-strain property because
of the fluctuation of the cross-sectional condition of the unit
composite filament yarn.
EXAMPLE 14
Nylon 66 having a relative viscosity of 2.8 and nylon 6 having a
relative viscosity of 3.0 both with respect to sulfuric acid were
used as the material polyamide polymers. 0.03 percent by weight of
potassium iodide and 0.03 percent by weight of copper iodide were
added to the chips of nylon 6 and nylon 66, respectively, before
spinning. A multifilament yarn of 4,000 denier/96 filaments, which
is composed of 25 percent by weight of nylon 6 and 75 percent by
weight of nylon 66, was manufactured at a spinning speed of 400
meters/min. by extruding the material molten polymers through the
some spinneret as that used in the preceding example. Then the
multifilament yarn obtained was stretched at a stretching ratio of
5.2 while heating with a heating plate maintained at 180.degree. C.
After stretching, the filament yarn obtained was provided with a
breaking strength of 8.2 g./denier and a breaking elongation of
17.9 percent. Next, 200 turns/meter of S-twists were imparted to
the stretched filament yarn. Then the twisted filament yarn was
heated at 230.degree. C. for 15 seconds without stretching. The
bonded filament yarn of the present invention thus obtained was
provided with a cross section wherein a plurality of nylon 66
island components were distributed uniformly within the nylon 6
matrix component formed by heat melting the nylon 6 sheath
component of all unit composite filament contained within the
multifilament yarn before stretching. By using such bonded filament
yarns as the material for a reinforcing cloth of a chafing strip
portion of a tubeless tire, it was possible to provide the tubeless
tire with better conformity to rubber and less leakage of air as
compared with a tubeless tire made of the conventional bonded
filament yarn.
UNIT COMPOSITE OF MULTIFILAMENTLIKE CONFIGURATION:
ITS MECHANISM, MANUFACTURE, UTILIZATION AND EXAMPLES
In the foregoing descriptions, references were made to a unit
composite having sheath-core configuration, however there is still
another typical example of the unit composite of the present
invention. This example of the unit composite is obtained in the
form of a bundle of filaments which contains a plurality of fine
island component-filaments and matrix component filaments.
The manufacturing method of the polyamide bonded filament yarn
composed of this type of unit composites is characterized by
simultaneously spinning more than two kinds of molten polymers
whose melting point differs from each other through a spinneret
which is provided with a plurality of spinning holes in such a
manner that holes for one polymer and holes for another polymer are
uniformly distributed, doubling a plurality of the unit composite
filaments thus obtained into a multifilament yarn and heating the
multifilament yarn at a heating temperature higher than the melting
point of one of the material polymer, thereby melting one of the
component polymers of each composite filament and converting the
multifilament yarn into a bonded filament yarn whose cross section
is composed of mutually continuous matrix portion and a plurality
of island portions almost uniformly distributed within the matrix
portion.
There is another process for carrying out the method of the present
invention, that is, after spinning both of the component polymers
independently into the respective filaments having almost a similar
cross-sectional area, these filaments are bundled into a
multifilament yarn and mixed together uniformly while stretching
the multifilament yarn. Next the multifilament yarn is heated in
order to melt one of the component polymer of each filament and
converting the multifilament yarn into a bonded filament yarn.
Heating of the multifilament yarn can be performed by utilizing the
dry heating system, the wet heating system, high frequency heating
system and infrared heating system.
As the material polymers used in the present invention, any
combination of polymers can be employed in so for as there is a
distinct difference in the melting points of polymers. This
difference in the melting point should preferably be larger than
10.degree. C. The content of both component polymer is dependent
upon the requirement of the end use. In case high degree of
strength is specially required for the bonded filament yarn
manufactured, the content of the component polymer having a lower
melting point must be larger than that of the component polymer
having a higher melting point. However this combination must be
reversed in case good flexibility and excellent resistance against
friction is especially required for the bonded filament yarn
manufactured. In order to satisfy both requirements, the content of
the component polymer having the lower melting point should range
between 10 and 60 percent by weight.
The multifilament yarn of the present invention can be made of
filaments whose thickness differs from each other and, if
necessary, suitable twist can be imparted into the bonded filament
yarn. Needless to say, the heating temperature of the multifilament
yarn should be lower than the melting point of the component
polymer having the higher melting point so as not to cause its
melting by heating.
Referring to FIG. 5, a cross section of an embodiment of a unit
composite of the present invention is shown. In the drawing, the
unit composite 5 of the present invention is presented in a form of
a bundle of filaments composed of a plurality of component core
filaments 6 of higher melting point and a plurality of component
filaments 7 of lower melting point. By bundling a plurality of such
unit composites 5 into a multifilament yarn, imparting twists if
necessary and heating the multifilament yarn at a temperature
between the melting point of both component polymers to effect
melting of component filaments 7, it is possible to obtain a bonded
filament yarn having a cross section shown in FIG. 6. In the
drawing, the bonded filament yarn 8 of the present invention is
composed of a matrix component 9, a plurality of island or core
components 10 randomly distributed in the matrix component 9 and a
plurality of air cells 11 formed during the manufacture of the
bonded filament yarn. It can be clearly understood that the island
component 10 of the bonded filament yarn 8 corresponds to the
component filament 6 of the unit composite 5, while the matrix
component 9 of the bonded filament yarn 8 corresponds to the
component filament 7 of the unit composite 5.
It should be noted that the presence of the plurality of air cells
11 plays an important role in the determination of the flexibility
of the bonded filament yarn manufactured, and this is one of the
characteristic features of the bonded filament yarn of the present
invention. The larger the number of such air cells in the cross
section of the bonded filament yarn, the higher is the flexibility
of the bonded filament yarn obtained.
Although it is provided with an apparent surface similar to that of
a conventional bonded filament yarn, the bonded filament yarn of
the present invention is provided with high flexibility and good
resilience which can not be expected of the conventional type of
bonded filament yarns. Besides, the resulting properties of the
bonded filament yarn manufactured can be varied over a wide range
in accordance with the requirement of the end use by adjusting the
content of component polymers, changing the combination of the
component polymers or by adjusting the number of air cells in the
cross section of the yarn. And such a wide range of property
results in a wide range of utilization of the bonded filament yarn
produced such as reinforcing cloths of tires, reinforcing cords of
V-belts, guts of rackets and bowstrings.
The following examples are illustrative of the present case of the
invention.
EXAMPLE 15
Nylon 6 was used as the lower melting point component polymer and
nylon 66 was used as the higher melting point component polymer.
The unit composite of 144 denier obtained was composed of randomly
mixed 24 component filaments half of which are nylon 6 component
filaments of 6 denier and the remaining half of which are nylon 66
components filaments of 6 denier. Then seven of such unit
composites were doubled into a multifilament yarn and 20 turns/10
cm. of S-twists were imparted to the doubled multifilament yarn.
Prior to heating, the twisted multifilament yarn was immersed into
an RFL solution for the purpose of providing a stronger bonding
ability to rubber. After squeezing, the multifilament yarn was
heated by a dry hot air maintained at 235.degree. C. for 45 seconds
without stretching, thereby nylon 6 component filaments were melted
to adhere to each other and the multifilament yarn was converted
into a bonded filament yarn. Using the polyamide bonded filament
yarns thus obtained, a woven cloth having the following
construction was produced.
The woven cloth obtained was used as a reinforcing cloth of a
chafing strip of a tubeless tire, by which air leakage was reduced
and has high resistance against friction.
EXAMPLE 16
Nylon 6 was used as the lower melting component polymer point and
polyethylene terephthalate was used as the higher melting point
component polymer. The unit composite of 144 denier obtained was
composed of randomly mixed 24 component filaments half of which are
nylon 6 component filaments of 6 denier and remaining half are
polyethylene terephthalate component filaments of 6 denier. Then,
six of such unit composites were doubled together and twisted in
the Z direction at a twisting rate of 10 turns/10 cm. Next, two of
the primary twisted yarns were doubled together and twisted into
the S-direction at a twisting rate of 20 turns/10 cm. Finally,
three of the secondary twisted yarns were further doubled together
and again twisted in the Z-direction at a twisting rate of 10
turns/10 cm. in order to form a cable cord. The cable cord obtained
heated by a dry hot air maintained at 240.degree. C. for 60 seconds
without stretching while treating with an RFL solution for the
purpose of stronger bonding ability to rubber.
The cable cord obtained was used as a reinforcing member of a
V-belt with excellent bonding ability to rubber and less separation
of cords.
EXAMPLE 17
The polyamide bonded filament yarn obtained in Example 15 was used
as guts of rackets. The gut obtained was provided with high
flexibility and strength and moderate elongation and
resilience.
In most of the foregoing examples, it was necessary for the
filament yarn of the present invention to be converted from a
multifilament yarn to a bonded filament yarn by heating the
multifilament yarn and melting the lower melting point component
filaments. However, in case the filament yarn of the present
invention is used for a woven cloth or a netted cloth which does
not have knot portions, it is desirable to use the multifilament
yarn without positively converting it into a bonded filament yarn
by heating.
Such a netted cloth can be manufactured from the multifilament
yarns of the present invention by weaving them into a woven-cloth
or by netting them into a netted cloth which does not have knot
portions. This manufactured woven or netted cloth is next heated at
a temperature between the respective melting points of the
component polymers of the unit composite contained within the
multifilament yarn. Then the component polymer of lower melting
point is melted by heating and the surface of the cloth is almost
completely covered with a layer of the molten component polymer of
the lower melting point.
Consequently, a cloth made of the multifilament yarn of the present
invention can preferably be used as a reinforcing cloth of a
tubeless tire chafer with air leakage eliminated effectively. This
is one of the outstanding features of the bonded filament yarn of
the present invention. Besides the intersections of the yarns do
not become as thick as in case of bonded filament yarns, because
the filament yarn of the present invention is constructed into
cloth while it is still in the form of multifilament yarns. This is
because the cross-sectional profile of the multifilament yarn can
be deformed more easily by stressing, which is usually the case
with weaving or netting, than that of a bonded filament yarn. By
heating the cloth as already mentioned, such intersections of yarns
are also melted and fixed to each other while each of the
multifilament yarn maintains its deformed cross-sectional profile.
As a result of this, there will be only a small difference in
thickness between the intersections and the other portions of the
cloth. Such small difference in thickness can result in effective
elimination of stress concentration upon the intersections of yarns
which often causes quick wearing out of a tire. This is another
outstanding feature of the bonded filament yarn of the present
invention.
With respect to the thickness of filament yarns, the thickness of a
multifilament yarn ranges between 210 and 3,360 denier, while the
thickness of a component filament is preferably smaller than 10
denier for the purpose of effective prevention of air leakage. The
number of meshes of the net should range between 100 and 50,000
meshes/10 cm..sup.2.
The following examples are illustrative of the multifilament of the
present invention.
EXAMPLE 18
Unit composites containing 60 percent by weight of nylon 66 as the
core component (.eta..sub.r =2.6) and 40 percent by weight of nylon
6 as the sheath component (.eta..sub.r =3.6) were bundled into a
multifilament yarn of 840 denier/136 filaments by using this
multifilament yarn. A woven cloth having following construction was
produced.
After this was heated at 230.degree. C. for 45 seconds using heated
air without stretching, the cloth was immersed into an RFL solution
for the purpose of improving the bonding ability to rubber and
further baked at 150.degree. C. for 2 minutes. The cloth obtained
was used for the chafing strip portion of a tire, by which leakage
of air was very small throughout the time the tire was actually
used. The resulting properties of the cloth manufactured are shown
in Table 3.
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TABLE 3
along warp Along filling direction direction
__________________________________________________________________________
Yarn density in ends 44 40 or picks/5 cm. (warp yarn) (filling
yarn) Thickness in mm. 0.69 Weight in g./m..sup.2 1.85 Breaking
strength in kg./3 cm. 105 89 Breaking elongation in % 19.5 21.3 Dry
heat* shrinkage in % 0 0
__________________________________________________________________________
*150.degree. C. .times. 30 min.
EXAMPLE 19
The same kind of woven cloth was obtained by the same method as in
the preceding example with only exception that the baking treatment
was carried out at 100.degree. C. for 2 minutes. However in the
present case, the heat treatment for melting component filaments of
lower melting point was applied to the cloth after the baking
treatment. The cloth obtained was used for the chafing strip
portion of a tire, by which leakage of air was very small
throughout the time the tire was actually used. The resulting
properties of the cloth manufactured are shown in Table 4.
---------------------------------------------------------------------------
TABLE 4
along warp Along filling direction direction
__________________________________________________________________________
Breaking strength 4.2 3.8 in kg. (warp) (filling) Breaking
elongation 21.0 22.9 in % (warp) (filling) Residual strength After
2 .times. 10.sup.5 times 92 -- of bending in % Bond strength by
H-test in 4.0 3.5 kg./1/4 inch
__________________________________________________________________________
EXAMPLE 20
Unit composites containing 70 percent by weight of nylon 6 as the
core component and 30 percent by weight of copolymerized nylon
6/nylon 66 as the sheath component were bundled into a
multifilament yarn of 840 denier/96 filaments. The melting point of
nylon 6 polymer was 218.degree. C. while the melting point of nylon
6/nylon 66 copolymer was 202.degree. C. Using the multifilament
yarn, a woven cloth having the same construction as that of Example
18 was produced. After heating with heated air of 210.degree. C.
for 45 seconds without stretching, the cloth was immersed into an
RFL solution for the purpose of improving the bonding ability to
rubber and further subjected to baking treatment at 150.degree. C.
for 2 minutes. The cloth obtained was used for the chafing strip
portion of a tire, by which leakage of air was very small
throughout the time the tire was actually used. The resulting
properties of the cloth manufactured are shown in Table 5.
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TABLE 5
along warp Along filling direction direction
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Yarn density in 44 40 ends or picks/5 cm. (warp yarn) (filling
yarn) Thickness in mm. 0.68 Weight in g./m..sup.2 181 Breaking
strength in kg./3 cm. 138 109 Breaking elongation in % 19.5 22.0
Bond strength by H-test in kg./1/4 inch 4.1 -- Amount of the
bonding agent bestowed in % 3.3 Residual strength after 2 .times.
10.sup.5 times 89 -- of bending in %
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EXAMPLE 21
Unit composites containing 70 percent by weight of
polyethyleneterephthalate as the core and 30 percent by weight of
nylon 6 as the sheath component were bundled into a multifilament
yarn of 210 denier/24 filaments. Using the multifilament yarn, a
woven cloth having the following construction was produced.
After receiving the heating and bonding treatments as in the
preceding examples, the cloth obtained was used with good results
for the chafing strip portion of a tire, by which leakage of air
was very small throughout the time the tire was actually used. The
resulting properties of the cloth manufactured are illustrated in
Table 6.
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TABLE 6
along warp Along filling direction direction
__________________________________________________________________________
Yarn density in 44 40 ends or picks/5 cm. (warp yarn) (filling
yarn) Thickness in mm 0.69 Weight in g./m..sup.2 210 Breaking
strength in kg./3 cm. 105 97 Breaking elongation in % 18.6 19.0
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As was repeatedly described above, the filament yarn of the present
invention can be used suitably for tire, especially for tubeless
tire, in the form of both bonded filament yarn and multifilament
yarn. In the utilization of the filament yarn of the present
invention, it is required to melt the matrix components of lower
melting point by heating the filament yarn at a temperature between
the melting points of both components while the filament yarn is
still in the form of multifilament yarns or after the filament yarn
is woven into a cloth. However it is also applicable, in accordance
with the purpose of the invention, to melt the matrix components of
the filament yarns after the reinforcing cloth made of them is
attached to the tire by carrying out the vulcanization of rubber at
a vulcanizing temperature between the melting points of both
components. By thus heating the tire during vulcanization, the
molten matrix components completely cover the islands components
and all molten matrix component is adhered to each other to become
continuous. This covering and continuously adhering condition of
the matrix component can be fixed over the entire reinforcing cloth
by cooling the tire after vulcanization and consequently, the
surface of the reinforcing cloth is completely covered with a
matrix component which prevents leakage of air therethrough.
The presence of air cell, rubberpiece or bonding agent within the
molten matrix component will not cause any leakage of air
therethrough.
Referring to FIG. 7, an embodiment of the utilization of the
reinforcing cloth of the present invention to a tubeless tire is
shown. In the drawing, a tubeless tire 12 is disposed to a rim, and
the reinforcing clothes 14 of the present invention are disposed to
the chafing strip portion 15 of the tire 12.
In order to avoid separation of both components within the filament
yarn manufactured by dynamic deformation subjected to the yarn
during actual utilization of the tire, the combination of the
component polymers must be selected in such a manner that the
mutual bonding ability of both components is strong enough to
withstand such a severe dynamic deformation. Generally, the
combination is preferably chosen from a group composed of polyamide
polymers. As the material polymer of the matrix components, the
polyamide polymer should be selected such that its melting point is
lower than the ordinary vulcanizing temperature of the tire, which
ranges between 150.degree. and 190.degree. C. Nylon 12 made of
.omega.-lauriclactum or a copolymerized polyamide containing at
least 80 percent by weight of .omega.-aminoundecan acid and
.omega.-lauriclactum are usually used for the matrix components of
the present invention, by which less damage by chemicals and
excellent adaptability to the actual processing processes
result.
With respect to the content of the components in the present case,
the content of the matrix component ranges from 10 to 60 percent by
weight while the corresponding content of the island component
ranges from 90 to 40 percent by weight, more preferably the content
of the former ranges from 20 to 60 percent by weight while the
corresponding content of the latter ranges from 80 to 20 percent by
weight.
The following examples are illustrative of the actual utilization
of the filament yarn of the present invention as a reinforcing
cloth of a tubeless tire.
EXAMPLE 22
Unit composites containing 70 percent by weight of nylon 6 as the
core component and 30 percent by weight of copolymerized
.omega.-lauriclactum/.epsilon.-caprolactum as the sheath component
were bundled into a multifilament yarn of 840 denier/60 filaments.
The copolymer was composed of 90 percent by weight of
.omega.-lauriclactum and 10 percent by weight of
.epsilon.-caprolactum and the melting point of the copolymer
measured by the optical method was 170.degree. C. The multifilament
yarn obtained was provided with a breaking strength of 8.0
g./denier and a breaking elongation of 18.5 percent after
stretching. Then the reinforcing cloth made of the multifilament
yarns was disposed to the chafing strip portion of a tubeless tire
having a size of 7.00-13. The tubeless tire was then subjected to
vulcanization treatment. Vulcanization of the tire was carried out
by B.O.M. vulcanizing machine by heating the tire for 15 minutes in
such a manner that the inside of the tire was heated with hot water
maintained at a temperature of 185.degree. C. and a pressure of 20
kg./cm..sup.2 and the outside of the tire was heated with steam of
175.degree. C. The tubeless tire obtained was had with excellent
resistance against friction with less leakage of air
therethrough.
EXAMPLE 23
Unit composites having an ordinary bimetallike configuration and
containing 50 percent by weight of nylon 12 and 50 percent by
weight of nylon 6 were bundled into a multifilament yarn of 840
denier/96 filaments. The optical melting point of nylon 12, which
was obtained by polymerizing .omega.-lauriclactum monomers, was
180.degree. C. and the relative viscosity of the polymer was 2.20
with respect to 1 percent solution of 98% sulfuric acid, while the
relative viscosity of nylon 6 was 3.3. The multifilament yarn
obtained was provided with a breaking strength of 8.3 g./denier and
a breaking elongation of 17.5 percent after stretching. Then the
multifilament yarns were disposed to the chafing strip portion of a
tubeless tire and then vulcanization treatment was applied by
heating the tire for 10 minutes in such a manner that the inside of
the tire was heated at 190.degree. C. and outside at 185.degree. C.
The tubeless tire obtained was provided with excellent resistance
against friction with less leakage of air therethrough.
While the invention has been described in conjunction with certain
embodiments thereof, various changes and modifications may be made
without departing from the spirit and scope of the invention.
* * * * *