U.S. patent application number 10/266783 was filed with the patent office on 2004-04-15 for conjugated yarn and fiber reinforced plastic.
This patent application is currently assigned to Japan Basic Material Co., Ltd.. Invention is credited to Kanno, Youichi, Sasaki, Fusako, Touse, Makoto, Yashima, Yoshinobu.
Application Number | 20040068972 10/266783 |
Document ID | / |
Family ID | 32738556 |
Filed Date | 2004-04-15 |
United States Patent
Application |
20040068972 |
Kind Code |
A1 |
Kanno, Youichi ; et
al. |
April 15, 2004 |
Conjugated yarn and fiber reinforced plastic
Abstract
A conjugated yarn is provided which is capable of preventing a
high-tenacity fiber used therein from being ruptured during a
weaving or knitting process. The conjugated yarn includes: core
yarns each having a high-tenacity fiber and a reinforcing fiber
positioned parallel with the high-tenacity fiber for reinforcing
the high-tenacity fiber; and a tying yarn bundling the core yarns.
Also provided is a fiber reinforced plastic of which the strength
and safety are improved by the use of the conjugated yarn.
Inventors: |
Kanno, Youichi;
(Fukushima-shi, JP) ; Sasaki, Fusako;
(Fukushima-shi, JP) ; Touse, Makoto;
(Fukushima-shi, JP) ; Yashima, Yoshinobu;
(Sendai-shi, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
Japan Basic Material Co.,
Ltd.
1-15-10, Oritate, Aoba-ku Miyagi-ken
Sendai-shi
JP
|
Family ID: |
32738556 |
Appl. No.: |
10/266783 |
Filed: |
October 9, 2002 |
Current U.S.
Class: |
57/210 |
Current CPC
Class: |
D02G 3/447 20130101;
D02G 3/38 20130101 |
Class at
Publication: |
057/210 |
International
Class: |
D02G 003/02 |
Claims
What is claimed is:
1. A conjugated yarn comprising: core yarns each comprising a
high-tenacity fiber and a reinforcing fiber positioned parallel
with the high-tenacity fiber for reinforcing the high-tenacity
fiber; and a tying yarn bundling the core yarns.
2. The conjugated yarn according to claim 1, wherein the
high-tenacity fiber comprises a plurality of high-tenacity
monofilaments.
3. The conjugated yarn according to claim 1 or 2, wherein the
reinforcing fiber comprises a plurality of reinforcing
monofilaments.
4. The conjugated yarn according to any one of claims 1 to 3,
wherein the reinforcing fiber has a higher resistance to flexural
fatigue than the high-tenacity fiber.
5. The conjugated yarn according to any one of claims 1 to 4,
wherein the reinforcing fiber has a higher tensile elongation at
break than the high-tenacity fiber.
6. The conjugated yarn according to any one of claims 1 to 5,
wherein the tying yarn has a higher tensile elongation at break
than the high-tenacity fiber.
7. The conjugated yarn according to any one of claims 1 to 6,
wherein the tying yarn is wound around the core yarns.
8. The conjugated yarn according to any one of claims 1 to 6,
wherein the tying yarn is braided around the core yarns.
9. The conjugated yarn according to any one of claims 1 to 8,
wherein the high-tenacity fiber comprises a carbon fiber.
10. The conjugated yarn according to any one of claims 1 to 9,
wherein the high-tenacity fiber comprises a glass fiber.
11. The conjugated yarn according to any one of claims 1 to 10,
wherein the high-tenacity fiber comprises a ceramic fiber.
12. A fiber reinforced plastic comprising a cured product
comprising a reinforcing fiber material formed of a conjugated yarn
as recited in any one of claims 1 to 11, and a resin matrix
impregnating the reinforcing fiber material.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a conjugated yarn for use
in weaving or knitting of a reinforcing fiber material to be used
to ensure the strength of a carbon fiber reinforced plastic
(hereinafter referred to as "CFRP") for example, and to a fiber
reinforced plastic (hereinafter referred to as "FRP") employing
such a conjugated yarn.
[0003] 2. Description of the Related Art
[0004] Various methods have been employed to manufacture CFRP
products such as shafts of golf clubs, fishing rods and
concrete-reinforcing members. Widely known ones of such methods
include, for example, a method (1) comprising the steps of: weaving
a fabric with a carbon fiber yarn; allowing the woven fabric to be
impregnated with a thermosetting resin to form a prepreg; forming
the prepreg into a product shape; and thermosetting the prepreg
thus shaped, and a method (2) comprising the steps of: weaving or
knitting a preform with a carbon fiber yarn; allowing the preform
to be impregnated with a resin matrix; and thermosetting the matrix
impregnating the preform.
[0005] Flexure stress works on such a carbon fiber yarn used in the
method (1) or (2) during the weaving or knitting process. If the
carbon fiber yarn is ruptured due to such flexure stress, a
resulting product cannot ensure a desired strength.
[0006] It has been a conventional practice to lower the weaving or
knitting speed or to coat the carbon fiber yarn with a reinforcing
resin in order to prevent rupture of such carbon fiber yarn.
However, the prior art still have a problem that a satisfactory
rupture-preventive effect cannot be provided.
[0007] On the other hand, conventional CFRPs involve a problem in
terms of safety because they might take dangerous forms when
broken. Specifically, though a golf club shaft or ski pole made of
metal for example is not ruptured but merely bent when damaged in
use, a golf club shaft or ski pole formed of CFRP is ruptured at a
damaged portion. Ruptured phases of such broken pieces might hurt
the body of the user or a person around the user.
[0008] Accordingly, it is a main object of the present invention to
provide a conjugated yarn which is prevented from being ruptured
during a weaving or knitting process.
[0009] Another object of the present invention is to provide a
conjugated yarn with which an FRP having higher strength and safety
can be prepared. Yet another object of the present invention is to
provide such an FRP having higher strength and safety.
SUMMARY OF THE INVENTION
[0010] According to a first aspect of the present invention, there
is provided a conjugated yarn: comprising core yarns each
comprising a high-tenacity fiber and a reinforcing fiber positioned
parallel with the high-tenacity fiber for reinforcing the
high-tenacity fiber; and a tying yarn bundling the core yarns.
[0011] Since the high-tenacity fiber (carbon fiber, glass fiber,
ceramic fiber or the like) and the reinforcing fiber are bundled
with the tying yarn in the conjugated yarn, the high-tenacity fiber
is reinforced by the reinforcing fiber during a weaving or knitting
process. Therefore, the high-tenacity fiber will not be ruptured
during such a process. An FRP employing the conjugated yarn
according to the first aspect of the invention exhibits a higher
strength as a whole than a conventional one and hence is hard to
break because the high-tenacity fiber forming a reinforcing
material is reinforced by the reinforcing fiber. When such an FRP
is broken, the reinforcing fiber and the tying yarn serve to tie a
broken portion to the rest. Accordingly, even if the high-tenacity
fiber is ruptured in the broken portion, the FRP is not ruptured as
a whole.
[0012] According to a second aspect of the present invention, there
is provided a fiber reinforced plastic comprising a cured product
comprising a reinforcing fiber material formed of a conjugated yarn
as recited above, and a resin matrix impregnating the reinforcing
fiber material.
[0013] These and other objects, features and attendant advantages
of the present invention will become apparent from the following
detailed description of the present invention when read in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a schematic view illustrating one embodiment of
the present invention; and
[0015] FIG. 2 is an enlarged sectional view taken on line II-II in
FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0016] The present invention will now be described in detail with
reference to the accompanying drawings.
[0017] A conjugated yarn 10 shown in FIG. 1 as one embodiment of
the present invention forms a reinforcing material for CFRPs used
to form golf club shafts, fishing rods, ski poles,
concrete-reinforcing members, aircraft parts, rocket parts and the
like.
[0018] The conjugated yarn 10 includes core yarns 16 each
comprising a high-tenacity fiber 12 and a reinforcing fiber 14, and
a tying yarn 18 wound around the core yarns 16.
[0019] The high-tenacity fiber 12 is a strand of carbon
monofilaments (i.e., high-tenacity monofilaments, hereinafter the
same) 12a having such characteristics as a low elongation, a high
elasticity modulus and a high strength. Specific examples of such
high-tenacity fibers 12 include Torayca produced by Toray
Industries Inc. and GRANOC produced by Nippon Graphite Fiber Co.,
Ltd.
[0020] The diameter of each carbon monofilament 12a forming the
high-tenacity fiber 12 is not particularly limited but is desirably
within a range of from 3 to 15 .mu.m from the viewpoint of
resistance to flexural fatigue. If the diameter of each carbon
monofilament 12a is less than 3 .mu.m, it is possible that carbon
monofilament 12a is ruptured during the carbon fiber conjugated
yarn making process. If the diameter is more than 15 .mu.m, carbon
monofilament 12a is easy to break when bent.
[0021] Typical carbon fibers include those of the acrylic type
which is obtained through sintering of acrylic fibers and those of
the pitch-based type which is obtained through sintering of pitch.
The high-tenacity fiber 12 (carbon monofilament 12a) used in this
embodiment may be of either type. The high-tenacity fiber 12 may
take the form of twisted yarn, untwisted yarn, no twist yarn or the
like. From the viewpoint of the balance between formability and
strength, the form of untwisted yarn or no twist yarn is
desirable.
[0022] The reinforcing fiber 14 serves as a splint for reinforcing
the high-tenacity fiber 12 and comprises a single or plural
reinforcing monofilaments 14a to be positioned parallel with the
high-tenacity fiber 12. Though there is no particular limitation on
the type of a fiber forming the reinforcing fiber 14 (reinforcing
monofilament 14a), it is desirable that the reinforcing fiber 14,
as a whole, exhibit a higher resistance to flexural fatigue than
the high-tenacity fiber 12. Examples of fibers having such a
property include titanium fiber, stainless steel fiber, TECHNORA
fiber, vinylon fiber, polyamide fiber, polyester fiber, polyvinyl
alcohol fiber, polyacrylonitrile fiber, and polyurethane fiber. Use
of polyester fiber or polyamide fiber is desirable because they are
inexpensive and easy to handle.
[0023] In order for the reinforcing fiber 14 to exhibit the CFRP
rupture preventive effect, it is desirable that the reinforcing
fiber 14 (reinforcing monofilament 14a) be made using a fiber such
as to impart the reinforcing fiber 14 with a higher resistance to
flexural fatigue and a higher tensile elongation at break than the
high-tenacity fiber 12. Examples of fibers having such properties
include titanium fiber, stainless steel fiber, TECHNORA fiber,
vinylon fiber, polyamide fiber, polyester fiber, polyvinyl alcohol
fiber, polyacrylonitrile fiber, and polyurethane fiber.
[0024] The tying yarn 18 serves to bundle the core yarns 16 (each
comprising carbon monofilament 12a and reinforcing monofilament
14a) and comprises a single or plural tying fibers 18a to be wound
around the core yarns 16. Though there is no particular limitation
on the type of a fiber forming the tying yarn 18 (tying fiber 18a),
the tying yarn 18 is desirably formed of a fiber having a superior
abrasion resistance because the tying yarn 18 becomes exposed on
the outer surface of the carbon fiber conjugated yarn 10. In order
for the tying yarn 18 to exhibit the CFRP rupture preventive
effect, it is desirable that the tying yarn 18 (tying fiber 18a) be
made using a fiber such as to impart the tying yarn 18 with a
higher resistance to flexural fatigue and a higher tensile
elongation at break than the high-tenacity fiber 12. Examples of
fibers having such properties include titanium fiber, stainless
steel fiber, TECHNORA fiber, vinylon fiber, polyamide fiber,
polyester fiber, polyvinyl alcohol fiber, polyacrylonitrile fiber,
and polyurethane fiber.
[0025] In making the conjugated yarn 10, the high-tenacity fibers
12 and the reinforcing fibers 14 are positioned parallel with each
other to form the core yarns 16 first. Subsequently, the tying
fiber 18a is wound around the core yarns 16 to cover the same using
an Italian-type twisting machine or a twisting machine for covering
for example.
[0026] To prevent torque from working on the conjugated yarn 10,
double-covering of the core yarns 16 with tying fibers 18a wound
around the core yarns 16 clockwise and counterclockwise is desired.
However, single-covering is sufficient to bundle the core yarns
16.
[0027] In preparing a CFRP (in the form of a golf club shaft, ski
pole or fishing rod) using the conjugated yarn 10 there is employed
any one of methods including a method (1) comprising the steps of:
weaving a fabric (reinforcing carbon fiber material) with
conjugated yarn 10; allowing the woven fabric to be impregnated
with a resin matrix to form a prepreg; forming the prepreg into a
product shape; and thermosetting the resin matrix forming the
prepreg, a method (2) comprising the steps of: weaving or knitting
a preform (reinforcing carbon fiber material) with conjugated yarn
10; allowing the preform to be impregnated with a resin matrix; and
thermosetting the matrix impregnating the preform.
[0028] Though flexure stress works on conjugated yarn 10 during the
weaving or knitting step of such a method, the high-tenacity fiber
12 reinforced by the reinforcing fiber 14 is not ruptured due to
such stress.
[0029] In the CFRP employing the conjugated yarn 10, the
high-tenacity fiber 12 forming the reinforcing material is
reinforced by the reinforcing fiber 14. Accordingly, if the
reinforcing fiber 14 comprises a fiber having a high resistance to
flexural fatigue, the CFRP is improved in strength as a whole. In
the case where the CFRP is applied to a golf club shaft for
example, the resulting golf club shaft is nervy and hence exhibits
considerably improved performance.
[0030] When the CFRP employing the conjugated yarn 10 is broken, it
is possible that the high-tenacity fiber 12 is ruptured in the
broken portion. However, the CFRP as a whole can be prevented from
being ruptured if the reinforcing fiber 14 and/or the tying fiber
18 are/is formed of a fiber having a high tensile elongation at
break.
[0031] That is, if the tensile elongation at break of the
reinforcing fiber 14 and/or the tying fiber 18 is higher than that
of the high-tenacity fiber 12, the high-tenacity fiber 12 is
ruptured first, followed by the occurrence of rupture of the
reinforcing fiber 14 and/or the tying fiber 18, provided an equal
breaking energy is applied. Actually, however, the breaking energy
is attenuated upon rupture of the high-tenacity fiber 12 and,
hence, the possibility that rupture of the reinforcing fiber 14
and/or the tying fiber 18 is reached is low. For this reason the
reinforcing fiber 14 and/or the tying fiber 18 play(s) the role of
tying the broken portion to the rest, thereby preventing the whole
CFRP from being ruptured in many cases. Accordingly, there is no
fear that the ruptured phases of any broken piece hurts a human
body.
[0032] The inventor of the present invention conducted the
following test to verify the effect of the present invention.
[0033] Test Method
[0034] There were provided a high-tenacity fiber consisting of a
carbon fiber (67Tex, 100f, 1.6% elongation), a comparative yarn
comprising the high-tenacity fiber bundled with a vinylon fiber
(30d), and a conjugated yarn comprising the high-tenacity fiber, a
stainless steel fiber (40 .mu.m, number of fibers=4) positioned
parallel with the high-tenacity fiber, and the vinylon fiber (30d)
bundling the high-tenacity fiber and the stainless steel fiber.
Three types of test samples (first to third test samples) each
comprising 11 test pieces were woven using the high-tenacity fiber,
comparative yarn and conjugated yarn, respectively, as weft and a
cotton yarn as warp. Each of the test samples (11 test pieces of
the three types) was subjected to a flexural test.
[0035] Each test sample was of plain weave and was sized about 3.5
cm in the warp direction.times.about 18 cm in the weft direction,
and the number of weft yarns of each test sample was 50.
[0036] Test Results
[0037] The test results were as shown in Tables 1 and 2. It was
found from the graph of Table 1 that: the first test sample
employing only the high-tenacity fiber (carbon fiber) as weft did
not exhibit a sufficient flexural strength; the flexural strength
of the second test sample employing the comparative yarn was still
insufficient; and the third test sample employing the conjugated
yarn 10 exhibited a very high flexural strength.
[0038] It can be predicted from the test results that a fabric
employing the high-tenacity fiber (carbon fiber) only might be
ruptured during the weaving process or the like, whereas a fabric
employing the conjugated yarn can solve the problem of rupture
because the flexural strength of this fabric is remarkably
enhanced.
1TABLE 2 Test Results First test Second test Third test sample
sample sample Strength/weight 1 1.3 1.7 ratio Average (gf-cm) 0.326
0.409 0.688 Standard error 0.057 0.020 0.044 Median 0.339 0.400
0.749 Mode # N/A # N/A # N/A Standard 0.190 0.068 0.146 deviation
Dispersion 0.036 0.005 0.021 Kurtosis -1.453 -1.334 -1.071 Degree
of 0.048 0.187 -0.567 distorsion Range 0.523 0.203 0.439 Minimum
0.081 0.312 0.453 Maximum 0.604 0.515 0.892 Total 3.586 4.495 7.568
Number of 11 11 11 samples
[0039] While the tying yarn 18 is wound around the core yarns 16 in
the foregoing embodiment, the tying yarn 18 may be braided around
the core yarns 16 using a braider (for example a braider
manufactured by KOKUBU TEKKO CO., LTD.).
[0040] The high-tenacity fiber 12 may be any fiber which has a low
resistance to flexural fatigue but exhibits a high tenacity or any
fiber which will take a dangerous broken form but exhibits a high
tenacity, for example, glass fiber or ceramic fiber.
[0041] It is possible that at least one of the high-tenacity fiber
12, reinforcing fiber 14 and tying yarn 18 may comprise at least
two types of fibers.
[0042] The conjugated yarn of the present invention may be used as
a reinforcing material for fiber reinforced concrete (FRC).
[0043] According to the present invention, it is possible to
prevent rupture of the high-tenacity fiber during a weaving or
knitting process. Thus, weaving or knitting at a higher speed
becomes possible, whereby the productivity of a reinforcing fiber
material or an FRP can be improved remarkably.
[0044] Since the high-tenacity fiber forming such a reinforcing
fiber material is reinforced by the reinforcing fiber, an FRP
employing the reinforcing fiber material has an enhanced strength
as a whole.
[0045] When the FRP employing the conjugated yarn of the present
invention is broken, it is possible that the high-tenacity fiber is
ruptured in the broken portion. However, the FRP as a whole can be
prevented from being ruptured because the reinforcing fiber and/or
the tying fiber play(s) the role of tying the broken portion to the
rest. Accordingly, there is no fear that the ruptured phases of any
broken piece hurts a human body and, hence, the FRP offers
remarkably improved safety.
[0046] While only presently preferred embodiments of the present
invention have been described in detail, as will be apparent for
those skilled in the art, certain changes and modifications can be
made in embodiments without departing from the spirit and scope of
the present invention as defined by the following claims.
* * * * *