U.S. patent application number 10/363051 was filed with the patent office on 2004-01-15 for composite material, formed product and prepreg.
Invention is credited to Kubomura, Kenji, Watanabe, Akihito.
Application Number | 20040009728 10/363051 |
Document ID | / |
Family ID | 18745303 |
Filed Date | 2004-01-15 |
United States Patent
Application |
20040009728 |
Kind Code |
A1 |
Kubomura, Kenji ; et
al. |
January 15, 2004 |
Composite material, formed product and prepreg
Abstract
A prepreg, including a laminated body impregnated with resin
having two triaxial woven fabrics prepregs(101) and an electrically
conductive non-woven fabric(102) are laminated each other, wherein
an antenna reflector is formed by laying up the prepreg, and the
non-woven fabric may be a heat conducting non-woven fabric, heat
insulating non-woven fabric, electrical conducting non-woven
fabric, electrical insulating non-woven fabric, heat conducting and
electrical conducting non-woven fabric, heat conducting and
electrical insulating non-woven fabric, heat insulating and
electrical conducting non-woven fabric, heat insulating and
electrical insulating non-woven fabric.
Inventors: |
Kubomura, Kenji; (Ishikawa,
JP) ; Watanabe, Akihito; (Fukui, JP) |
Correspondence
Address: |
Barry E Bretschneider
Morrison & Foerster
2000 Pennsylvania Avenue N W
Washington
DC
20006-1888
US
|
Family ID: |
18745303 |
Appl. No.: |
10/363051 |
Filed: |
June 25, 2003 |
PCT Filed: |
August 28, 2001 |
PCT NO: |
PCT/JP01/07393 |
Current U.S.
Class: |
442/205 |
Current CPC
Class: |
B29C 70/882 20130101;
B29L 2031/3456 20130101; B29C 70/22 20130101; Y10T 442/3195
20150401; B32B 5/26 20130101; B32B 5/28 20130101 |
Class at
Publication: |
442/205 |
International
Class: |
D03D 011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 28, 2000 |
JP |
2000-256740 |
Claims
1. A composite material: wherein at least one or more triaxial
woven fabrics and at least one or more non-woven fabrics are
laminated, and thereby a laminated body is formed; and the
laminated body is impregnated with a resin.
2. A composite material: wherein at least one or more triaxial
woven fabrics impregnated with a resin and at least one or more
non-woven fabrics impregnated with a resin are laminated.
3. A composite material: wherein at least one or more triaxial
woven fabrics impregnated with a resin and at least one or more
non-woven fabrics are laminated.
4. A composite material as set forth in any one of claims 1 through
3: wherein the triaxial woven fabrics and the non-woven fabrics are
alternately laminated.
5. A composite material as set forth in any one of claims 1 through
4: wherein the resin is in a not completely cured state.
6. A composite material as set forth in any one of claims 1 through
5: wherein the non-woven fabric has electrical conducting
properties.
7. A composite material as set forth in any one of claims 1 through
5: wherein the non-woven fabric has electrical insulating
properties.
8. A composite material as set forth in any one of claims 1 through
7: wherein the non-woven fabric has heat conducting properties.
9. A composite material as set forth in anyone of claims 1 through
7: wherein the non-woven fabric has heat insulating properties.
10. A molded body: wherein at least one or more triaxial woven
fabrics and one or more non-woven fabrics are laminated, and
thereby a laminated body is formed; the laminated body is
impregnated with a resin, and thereby a composite material is
formed; the composite material is laid-up in a mold in a state
where the resin is not completely cured; and the resin of the
laid-up composite material is cured, and thereby a molded body is
formed.
11. A molded body: wherein at least one or more triaxial woven
fabrics impregnated with a resin and one or more non-woven fabrics
impregnated with a resin are mutually laminated in a state where
the resins are not completely cured, and thereby a composite
material is formed; the composite material is laid-up in a mold;
and the resin of the laid-up composite material is cured, and
thereby a molded body is formed.
12. A molded body: wherein at least one or more triaxial woven
fabrics impregnated with a resin and one or more non-woven fabrics
are laminated in a state where the resin of the triaxial woven
fabric is not completely cured, and thereby a composite material is
formed; the composite material is laid-up in a mold; and the resin
of the laid-up composite material is cured, and thereby a molded
body is formed.
13. A molded body: wherein at least one or more triaxial woven
fabrics and one or more non-woven fabrics are laminated, and
thereby a laminated body is formed; the laminated body, while
impregnating with a resin, is laid-up in a mold; and the resin of
the laid-up laminated body is cured, and thereby a molded body is
formed.
14. A molded body: wherein a non-woven fabric is laminated with a
triaxial woven fabric impregnated with a resin, and thereby a
laminated body is formed; and the laminated body is laid-up
followed by curing the resin, and thereby a molded body is
formed.
15. A molded body as set forth in any one of claims 10 through 14:
wherein the non-woven fabric has electrical conducting
properties.
16. A molded body as set forth in any one of claims 10 through 14:
wherein the non-woven fabric has electrical insulating
properties.
17. A molded body as set forth in any one of claims 10 through 16:
wherein the non-woven fabric has heat conducting properties.
18. A molded body as set forth in any one of claims 10 through 16:
wherein the non-woven fabric has heat insulating properties.
19. A prepreg: wherein triaxial woven fabrics of reinforcement
fiber and electrical conducting non-woven fabrics are alternately
or in an arbitrary order laminated followed by impregnating with a
resin, and thereby a prepreg is formed.
20. A prepreg: wherein prepregs formed by impregnating triaxial
woven fabrics of reinforcement fiber with a resin and prepregs
formed by impregnating electrical conducting non-woven fabrics with
a resin are alternately or in an arbitrary order laminated, and
thereby a prepreg is formed.
21. A composite material: wherein the prepregs set forth in claim
19 or 20 are mutually laminated or the prepreg set forth in claim
19 or 20 and a prepreg having other structure are laminated, and
thereby a composite material is formed.
22. A composite material: wherein triaxial woven fabrics of
reinforcement fiber and electrical conducting non-woven fabrics are
alternately or in an arbitrary order laminated followed by
impregnating with a resin and by curing, and thereby a composite
material is formed.
Description
TECHNICAL FIELD
[0001] The invention relates to a composite material that uses a
triaxial woven fabric including, for instance, a prepreg in which a
resin is not completely cured, and a molded body made of the
composite material, in particular, to a composite material that is
light in weight, large in the mechanical strength and endowed with
the electrical conducting properties, the electrical insulating
properties, the heat conducting properties and the heat insulating
properties, a molded body and prepreg.
BACKGROUND ART
[0002] In composite materials that are used in existing structured
bodies, reinforcement fibers are impregnated with a resin. In the
following, such composite materials are referred to as
"fiber-reinforced resin composite materials".
[0003] In the fiber-reinforced resin composite material,
combinations of reinforcement fibers and resins to be a matrix can
be properly selected.
[0004] Accordingly, the fiber-reinforced resin composite materials
can be endowed with the physical and chemical properties that are
appropriate for service conditions thereof.
[0005] As a result, the fiber-reinforced resin composite materials
are used in many application fields.
[0006] Furthermore, the fiber-reinforced resin composite materials
are high in the specific strength and excellent in the corrosion
resistance. Accordingly, the fiber-reinforced resin composite
materials are suitable for structured bodies that are light in the
weight and subjected to large stress, resulting in finding
applications in many fields.
[0007] As a molded body that uses the fiber-reinforced resin
composite material, there is an antenna's structural material for
use with an artificial satellite.
[0008] For instance, JP-A-11-168321 discloses a planar antenna
device.
[0009] In the planar antenna device, metal radiation elements are
arranged on a thin film (first film) of KFRP (Kevlar (Trade mark)
fiber-reinforced plastic).
[0010] The above Kevlar belongs to aramid fiber.
[0011] In front of the first film, a KFRP film (second film) is
similarly disposed so as to face the first film.
[0012] The second film is provided with a ground conductor metal
film such as a metal film and so on.
[0013] The first film is used as a radiation element sheet and the
second film is used as a ground conductor sheet.
[0014] The first film and the second film are expanded into planes
by use of an expansion mechanism.
[0015] The expanded first film and second film constitute a planar
antenna.
[0016] An existing planar antenna configuration will be explained
with reference to FIG. 4. FIG. 4 is a schematic diagram of an
existing planar antenna.
[0017] The configuration of the existing planar antenna, as shown
in FIG. 4, is provided on a KFRP film 401 with circular patches 405
to be metal elements.
[0018] Furthermore, in a ground conductor film 404 of the existing
planar antenna, a metal film or fibers made of a metal such as
copper are formed tissue-like as if straining paper.
[0019] In the existing planar antenna configuration, the KFRP film
403 is provided with the ground conductor film 404.
[0020] Furthermore, the KFRP films 401 and 403 are adhered and
fixed to a frame-like dielectric material (frame-like member) 402
made of CFRP (carbon fiber-reinforced plastic) and expanded into
planes by use of an expansion mechanism.
[0021] Thus, the existing planar antenna, by supporting the metal
elements and the ground conductor layer with the expansion
mechanism such as the CFRP frame member and so on and the films
such as the KFRP, accomplishes lighter weight.
[0022] However, in a reflector (antenna reflector) of the antenna,
different from the planar antenna, a conductive layer has to be
expanded with a definite shape.
[0023] Furthermore, depending on the application circumstances, the
antenna reflector itself is demanded to have sufficient mechanical
strength.
[0024] Still furthermore, depending on the application
circumstances, the antenna reflector is demanded to have
spring-back properties with which the antenna reflector can restore
its original state even after temporarily deformed owing to load
stress and so on.
[0025] Accordingly, in the application to the antenna reflector and
so on, a structure in which metal fiber tissue is provided to the
KFRP film, being deficient in the self-sustaining properties
because of being film-like or sheet-like, cannot function.
[0026] Accordingly, in the antenna, the fiber-reinforced resin
composite material is molded into a three-dimensional curve such as
a paraboloid, and thereby the reflector is constituted.
[0027] However, the antenna, in order to form an electromagnetic
wave reflection surface, has to be endowed with the electrical
conducting properties.
[0028] Accordingly, in the existing antennas, such structures as
that in the triaxial woven fabric itself, as the reinforcement
fiber of the composite material that constitutes the
three-dimensional curved surface, conductive carbon fiber is used,
or plating is applied on a surface of the molded body made of the
composite materials, or a metal foil is laminated are adopted.
[0029] However, when the carbon fiber is used in the triaxial woven
fabric as the reinforcement fiber of the composite material, the
carbon fiber that is high in the electric conductivity, being high
in the elastic modulus, is difficult to weave and mold, resulting
in pushing up the manufacturing cost.
[0030] Furthermore, when the carbon fiber is used in the triaxial
woven fabric as the reinforcement fiber of the composite material,
the carbon fiber that is high in the electric conductivity, being
at most 1.9.times.10.sup.-4 .OMEGA..multidot.cm in the volume
resistivity, is not sufficient in enhancing the electromagnetic
wave reflectance or in coping with higher frequencies.
[0031] Still furthermore, the antenna has a very large dimension
and shape in a molded state. Accordingly, also when a surface of
the composite material that is shaped into the antenna is plated,
irrespective of wet or dry process, there is restriction on a
magnitude of a processing bath or chamber, and the adhesion of the
plating can be uniformly applied with difficulty.
[0032] Furthermore, when the plating is carried out according to a
wet process, a plating liquid unfavorably erodes the composite
material or is absorbed by the composite material.
[0033] Still furthermore, when the metal foil is stuck onto a
surface of the molded composite material, since, in an artificial
satellite antenna reflector or the like that is finished very light
in the weight, a molded body is very thin, even owing to only a
slight stress generated on a surface thereof, warp is caused and
deformation results, or when adhesive force is suppressed to
inhibit the deformation from occurring, the metal foil peels
off.
[0034] Furthermore, when an artificial satellite is launched, a
very high-energy acoustic vibration due to a boost gas that
accompanies a shock wave of a rocket is transmitted even to the
inside of a fairing where the antenna is housed.
[0035] Accordingly, in the artificial satellite antenna, the
surface of the metal foil is in some cases broken. When in order to
inhibit the metal foil surface from breaking, a thickness of the
metal foil is larger, the heavy weight results.
[0036] In addition, the metal foil originally has a two-dimensional
plane and, when being stuck to a three-dimensionally curved surface
of the antenna, has no conformability to the curved surface.
Accordingly, it is difficult to form a three-dimensional antenna
with a single metal foil.
[0037] Furthermore, when metal foils that are divided and cut in
conformity with a three-dimensional shape are stuck together and
thereby a three-dimensionally curved surface is formed, since an
adhesive remains between stuck surfaces, the metal foils cannot be
stuck with the electric conductivity maintaining.
[0038] In order to cope with such problems, although it has been
tried to constitute the antenna with a non-woven fabric made of
metal fibers, non-woven metal fabric alone, being low in both the
mechanical strength and the elastic modulus, cannot work as a
structural material in this application.
[0039] On the other hand, in a molded body that is used in, for
instance, space, other than the electrical conducting properties,
for instance in the case of an antenna, the heat conducting
properties in a thickness direction, the electrical insulating
properties, and the heat insulating properties are also demanded.
However, it is difficult for the existing material to give these
characteristics.
[0040] The invention is carried out in view of the above problems
and intends to provide a composite material that has the mechanical
strength, the elastic modulus and high specific strength that are
similar to that of the fiber-reinforced resin composite material,
and at least any one of the electrical conducting properties
comparable to metal materials, the electrical insulating
properties, the heat conducting properties and the heat insulating
properties, a molded body and a prepreg.
DISCLOSURE OF THE INVENTION
[0041] In a composite material according to the invention, at least
one or more triaxial woven fabrics and at least one or more
non-woven fabrics are laminated, thereby a laminated body is
formed, and the laminated body is impregnated with a resin.
[0042] Furthermore, in a composite material according to the
invention, at least one or more triaxial woven fabrics impregnated
with a resin and at least one or more non-woven fabrics impregnated
with a resin are laminated.
[0043] Still furthermore, in a composite material according to the
invention, at least one or more triaxial woven fabrics impregnated
with a resin and at least one or more non-woven fabrics are
laminated.
[0044] Furthermore, in a composite material according to the
invention, the triaxial woven fabrics and the non-woven fabrics are
alternately laminated.
[0045] Still furthermore, in a composite material according to the
invention, the resin is in a not completely cured state.
[0046] Furthermore, in a composite material according to the
invention, the non-wove fabric has the electrical conducting
properties.
[0047] Still furthermore, in a composite material according to the
invention, the non-woven fabric has the electrical insulating
properties.
[0048] Furthermore, in a composite material according to the
invention, the non-woven fabric has the heat conducting
properties.
[0049] Still furthermore, in a composite material according to the
invention, the non-woven fabric has the heat insulating
properties.
[0050] Furthermore, in a molded body according to the invention, at
least one or more triaxial woven fabrics and one or more non-woven
fabrics are laminated, thereby a laminated body is formed, the
laminated body is impregnated with a resin, thereby a composite
material is formed, the composite material is laid-up in a mold in
a state where the resin is not completely cured followed by curing
the resin of the laid-up composite material, and thereby a molded
body is formed.
[0051] Still furthermore, in a molded body according to the
invention, at least one or more triaxial woven fabrics impregnated
with a resin and at least one or more non-woven fabrics impregnated
with a resin are mutually laminated in a state where the resins are
not completely cured and thereby a composite material is formed,
the composite material is laid up in a mold followed by curing the
resin in the laid-up composite material, and thereby a molded body
is formed.
[0052] Furthermore, in a molded body according to the invention, at
least one or more triaxial woven fabrics impregnated with a resin
and at least one or more non-woven fabrics are laminated in a state
where the resin of the triaxial woven fabric is not completely
cured and thereby a composite material is formed, the composite
material is laid up in a mold followed by curing the resin in the
laid-up composite material, and thereby a molded body is
formed.
[0053] Still furthermore, in a molded body according to the
invention, at least one or more triaxial woven fabrics and at least
one or more non-woven fabrics are laminated to form a laminated
body, the laminated body is laid up in a mold with the laminated
body impregnating with a resin followed by curing the resin in the
laid-up laminated body, and thereby a molded body is formed.
[0054] Furthermore, in a molded body according to the invention, a
triaxial woven fabric impregnated with a resin and a non-woven
fabric are laminated and thereby a laminated body is formed, the
laminated body is laid up followed by curing the resin, and thereby
a molded body is formed.
[0055] Still furthermore, in a molded body according to the
invention, the non-wove fabric has the electrical conducting
properties.
[0056] Furthermore, in a molded body according to the invention,
the non-woven fabric has the electrical insulating properties.
[0057] Still furthermore, in a molded body according to the
invention, the non-woven fabric has the heat conducting
properties.
[0058] Furthermore, in a molded body according to the invention,
the non-woven fabric has the heat insulating properties.
[0059] Still furthermore, in a prepreg according to the invention,
triaxial woven fabrics of reinforcement fiber and conductive
non-woven fabrics are alternately or in an arbitrary order
laminated followed by impregnating with a resin, and thereby a
prepreg is formed.
[0060] Furthermore, in a prepreg according to the invention,
prepregs formed by impregnating triaxial woven fabrics of
reinforcement fiber with a resin and prepregs formed by
impregnating conductive non-woven fabrics with a resin are
alternately or in an arbitrary order laminated, and thereby a
prepreg is formed.
[0061] Furthermore, in a composite material according to the
invention, the above prepregs are mutually laminated or the above
prepreg is laminated with a prepreg having another structure.
[0062] Still furthermore, in a composite material according to the
invention, triaxial woven fabrics made of reinforcement fiber and
conductive non-woven fabrics are alternately or in an arbitrary
order laminated followed by impregnating with a resin and further
followed by curing, and thereby the composite material is
formed.
[0063] Here, a prepreg in the specification is one kind of
composite materials and is one (intermediate base material) in
which a fiber base material such as a triaxial woven fabric, a
unidirectional material and a biaxial fabric is impregnated with a
resin and the resin is maintained in a semi-cured state (a state
that is not completely cured).
[0064] Furthermore, in the specification, as methods and conditions
of curing the prepreg, as one example, the following methods and
conditions can be used.
[0065] The composite material prior to the curing according to one
example of the following methods and conditions is a prepreg.
[0066] (Method)
[0067] 1. Compression molding, 2. Vacuum bag molding, 3. Autoclave
molding, 4. Fiber placement molding, 5. Sheet winding molding, 6.
Rolling table molding and so on.
[0068] (Conditions)
[0069] Curing temperature: 120 to 180 degree centigrade.
[0070] Curing time period: 1 to 3 hours.
[0071] Molding pressure: atmospheric pressure to 0.6 MPa.
[0072] Furthermore, "lay-up" means an operation by which the fiber
base material or prepreg (is cut, stuck and laminated) is given a
shape on a mold.
[0073] Still furthermore, a non-woven fabric is one in which short
fibers are entangled and formed into a sheet. Paper, felt and
absorbent cotton can be said as one of the non-woven fabrics.
[0074] As the characteristics of the non-woven fabric, it can be
cited that the non-woven fabric is physically pseudo-isotropic.
[0075] That is, since the non-woven fabric can well conform to a
three-dimensionally curved surface and a shape having a sharp angle
portion, wrinkle is caused with difficulty. Furthermore, the
non-woven fabric, in the case of being laminated with the other
material, can be peeled with difficulty. This is evident in the
thermal shock test and the peel test.
[0076] Furthermore, the non-woven fabric, after folding, leaves a
fold line with difficulty, and after expansion, its function does
not disappear.
[0077] Still furthermore, the non-woven fabric, having voids in
comparison with the metal foil or the like, is low in the density,
resulting in lighter weight.
[0078] Furthermore, the non-woven fabric, having voids, can
withstand sound or vibration at the launch of a rocket, resulting
in neither breaking nor peeling.
[0079] Still furthermore, the electrical conducting properties and
the heat conducting properties of the non-woven fabric, in the case
of the metal fibers being used or the metal plating being applied,
reflect the characteristics of the metal.
[0080] Thus, when the electrical conducting and heat conducting
non-woven fabric is used in the composite material, the invention
exhibits the following effects.
[0081] So far, carbon fiber composite materials, being high in the
elastic modulus, light in the weight, very small in the thermal
expansion coefficient, and high in the heat conducting properties
in a fiber length direction, have been used in almost all members
of an artificial satellite.
[0082] However, because the heat conducting properties in a
direction perpendicular to a fiber axis of the carbon fiber are low
and the heat conducting properties of the matrix resin are very
low, the heat conducting properties in a thickness direction of the
carbon fiber composite material are low. Accordingly, the capacity
of releasing heat in a thickness direction is very low.
[0083] Here, a matrix resin means a resin for use in the matrix,
that is, a resin that becomes a matrix(base material).
[0084] Also in the reinforcement fiber, a resin called a sizing
agent is used. Accordingly, an ordinary resin and the matrix resin
are called differently. However, in general, a resin of the
composite material is a resin for use in the matrix.
[0085] The composite materials such as the fiber-reinforced
plastics (FRP) and polymer matrix composites (PMC), largely
divided, are made of three constituents.
[0086] a reinforcement fiber.
[0087] a matrix(base material): a resin in the case of the PMC.
[0088] an interface between the reinforcement fiber and the
matrix.
[0089] In the case of the PMC, the matrix is a resin (polymer), in
the case of MMC (metal matrix composite), the matrix is a metal,
and in the case of CMC (ceramic matrix composite), the matrix(base
material) is ceramics.
[0090] When high heat dissipation from a thickness direction can be
obtained in the carbon fiber-reinforced composite material, a heat
dissipation structure of the artificial satellite can be dispensed
with or may be simplified.
[0091] That is, as in the invention, when the electrical conducting
and heat conducting non-woven fabric is used as the non-woven
fabric, the invention can contribute to the artificial satellite in
an improvement in the performance, reduction in the weight and
reduction in the cost.
[0092] In the invention where the electrically insulating and heat
conducting non-woven fabric is used in the composite material, the
composite material can be used like a printed substrate (one in
which a front surface and a rear surface are fundamentally
insulated).
[0093] Such composite material exhibits heat dissipation effect in
a mounted electronic device and an onboard device that requires
insulation.
[0094] Furthermore, in a composite material according to the
invention, by laminating the non-woven fabric to the triaxial woven
fabric, proper heat conducting properties (heat dissipation
properties) and heat insulating properties can be given to
necessary portions.
[0095] Accordingly, when the composite material according to the
invention is used in, for instance, a bus (body structure) of an
artificial satellite and a solar battery paddle thereof, to
portions where the heat control is necessary of these, necessary
heat control can be easily given by use of the existing method.
BRIEF DESCRIPTION OF THE DRAWINGS
[0096] FIG. 1 is a schematic diagram showing one embodiment of a
composite material according to the invention,
[0097] FIG. 2 is a partial enlargement diagram of a triaxial woven
fabric used in one embodiment of the composite material according
to the invention,
[0098] FIG. 3 is a schematic diagram of an antenna reflector as a
molded body according to the invention, and
[0099] FIG. 4 is a schematic diagram of an existing planar antenna
structure.
BEST MODE FOR CARRYING OUT THE INVENTION
[0100] In order to give more detailed explanation of the invention,
the invention will be explained in accordance with the attached
drawings. The explanation of an embodiment of the composite
material according to the invention can be also applied to that of
a prepreg according to the invention.
[0101] That is, in composite materials according to the invention,
one in which a resin of the composite material is not completely
cured is a prepreg.
[0102] (Explanation of One Embodiment of Composite Material)
[0103] One embodiment of the composite material according to the
invention has a structure called a symmetrically laminated
structure that includes the non-woven fabric that is laminated in
an order of, for instance, triaxial woven fabric/non-woven
fabric/triaxial woven fabric, or non-woven fabric/triaxial woven
fabric/non-woven fabric.
[0104] Furthermore, when a plurality of the triaxial woven fabrics
is laminated, between arbitrary layers the non-woven fabric may be
interposed.
[0105] That is, in one embodiment of the composite material
according to the invention, the triaxial woven fabrics and the
non-woven fabrics may be arbitrarily laminated.
[0106] Here, the lamination means, irrespective of the kinds of the
layers, to stack two or more layers. In the invention, the
non-woven fabric layer is stacked onto the triaxial woven fabric
layer.
[0107] Furthermore, the non-woven fabric interposed between the
triaxial woven fabrics may not be sheet-like, that is, at least one
or more non-woven fabrics having an arbitrary shape such as a
circular, polygonal or elliptical shape may be interposed between
the triaxial woven fabrics.
[0108] Owing to such structure of the composite material, thermal
strain can be minimized, and furthermore when the non-woven fabric
is interposed between appropriate layers made of the triaxial woven
fabrics, higher density strength can be obtained.
[0109] Furthermore, in one embodiment of the composite material
according to the invention, the triaxial woven fabrics of the
reinforcement fiber and the non-woven fabrics are laminated
alternately or in an arbitrary order followed by impregnating with
a resin.
[0110] In the composite material impregnated with a resin, when the
resin is not completely cured, it is a prepreg.
[0111] Furthermore, in one embodiment of a composite material
according to the invention, prepregs in which the triaxial woven
fabric is impregnated with a resin and prepregs in which the
non-woven fabric is impregnated with a resin may be alternately or
in an arbitrary order laminated.
[0112] When the composite materials are kept in the prepreg state,
by appropriately selecting combinations thereof, composite
materials having necessary structures/characteristics can be
formed.
[0113] Furthermore, in one embodiment of a composite material
according to the invention, a composite material having an
arbitrary shape may be formed by mutually laminating the prepregs,
or, as needs arise, by further laminating thereon a prepreg having
other structure, followed by curing.
[0114] Still furthermore, in one embodiment of a composite material
according to the invention, the triaxial woven fabrics of
reinforcement fiber and the non-woven fabrics are alternately or in
an arbitrary order laminated, impregnated with a resin, cured, and
thereby the composite material can be obtained.
[0115] Here, as a method in which the triaxial woven fabric and the
non-woven fabric are laminated to obtain a composite material, and
therefrom a molded body is obtained, the following variations can
be considered. It goes without saying that the invention is not
restricted to the following variations and even other methods can
be used.
[0116] 1. At least one or more triaxial woven fabrics and at least
one or more non-woven fabrics are laminated followed by
impregnating with a resin, and thereby forming a prepreg. The
prepreg is laid-up in a mold followed by curing, and thereby a
molded body is obtained.
[0117] 2. A prepreg in which at least one or more triaxial woven
fabrics are impregnated with a resin and a prepreg in which at
least one or more non-woven fabrics are impregnated with a resin
are laminated. The obtained prepreg is laid-up in a mold followed
by curing, and thereby a molded body is obtained.
[0118] 3. A prepreg in which at least one or more triaxial woven
fabrics are impregnated with a resin and at least one or more
non-woven fabrics (not impregnated with a resin) are laminated. The
obtained prepreg is laid-up in a mold followed by curing, and
thereby a molded body is obtained.
[0119] 4. At least one or more triaxial woven fabrics and at least
one or more non-woven fabrics are laminated, laid-up in a mold
while impregnating with a resin followed by curing, and thereby a
molded body is obtained.
[0120] 5. At least one or more triaxial woven fabrics are
impregnated with a resin, at least one or more non-woven fabrics
are laminated thereon followed by laying-up in a mold further
followed by curing, and thereby a molded body is obtained.
[0121] Furthermore, the lamination in a method in which the
triaxial woven fabric and the non-woven fabric are laminated and
thereby a composite material is obtained contains not only a case
where at least one or more triaxial woven fabrics and at least one
or more non-woven fabrics are arbitrarily laminated but also a case
where both are alternately laminated.
[0122] Here, as the method of impregnating with a resin, the
following methods can be cited.
[0123] 1. A resin film is transcribed on a fiber base material
followed by compressing and heating to impregnate, and thereby a
semi-cured prepreg is obtained (it is called a dry (hot-melt)
method).
[0124] 2. A fiber base material is impregnated with a resin liquid
followed by compressing and heating, and thereby a semi-cured
prepreg is obtained (it is called a wet (impregnating) method).
[0125] Furthermore, when a molded body according to the invention
is generated, a prepreg (semi-cured intermediate base material)
process may be omitted.
[0126] That is, according to hand lay-up molding in which the fiber
base material and the non-woven fabric are directly impregnated
with a resin liquid in a mold followed by curing, or autoclave
molding in which a resin film is directly transcribed onto a fiber
base material and laying-up and molding in an autoclave as it is
further followed by curing, a molded body can be obtained.
[0127] Furthermore, there is a method called an RTM molding in
which the fiber base material and the non-woven fabric are set in a
mold (it is called a preform) followed by injecting a resin liquid
and curing, and thereby a molded body is obtained.
[0128] Here, as one embodiment of a composite material according to
the invention, an example of a laminate structure of the triaxial
woven fabric and the non-woven fabric is shown in FIG. 1. FIG. 1 is
a schematic diagram of one embodiment of the composite material
according to the invention.
[0129] In the composite material shown in FIG. 1, as the non-woven
fabric a conductive non-woven fabric is used. The composite
material shown in FIG. 1 has a sandwich-like structure in which a
conductive non-woven fabric 102 is interposed between two triaxial
woven fabric prepregs 101.
[0130] The triaxial woven fabric prepreg 101 is one in which the
triaxial woven fabric of reinforcement fiber is impregnated with a
resin. Furthermore, the resin with which the triaxial woven fabric
prepreg 101 is impregnated is not completely cured.
[0131] The laminated bodies may be impregnated with a matrix resin
followed by molding into a target shape further followed by
curing.
[0132] Furthermore, in a weave structure of the triaxial woven
fabric, there are formed hexagonal through holes 201 that
interconnect a front and rear surfaces as shown in FIG. 2.
[0133] Accordingly, by controlling a magnitude of the through holes
201 according to a weaving method of the triaxial woven fabric,
electrical conduction can be established between the conductive
non-woven fabrics disposed on the front and rear surfaces of the
interposed triaxial woven fabric. FIG. 2 is a partially enlarged
diagram of the triaxial woven fabric used in one embodiment of the
composite material according to the invention.
[0134] In a structure of the composite material such as shown in
FIG. 1, by laminating an appropriate number of the triaxial woven
fabric prepregs 101 made of reinforcement fiber and the non-woven
fabrics 102, both the mechanical characteristics and the electrical
characteristics can be controlled and improved.
[0135] Furthermore, for instance, since there are the through holes
201 of the triaxial woven fabric prepreg 101, for instance, when
the electrical conducting non-woven fabric is used as the non-woven
fabric, the composite material can be provided with the electrical
conducting properties in a thickness direction thereof.
[0136] Here, the thickness direction means a direction
substantially vertical to a sheet surface of the triaxial woven
fabric prepreg 101 shown in, for instance, FIG. 1.
[0137] Accordingly, in the case of a molded body that uses the
composite material shown in, for instance, FIG. 1, excellent
electrical conducting properties can be established even in a
thickness direction thereof.
[0138] Furthermore, for instance, since there are through holes 201
of the triaxial woven fabric prepreg 101, for instance, when the
heat conducting non-woven fabric is used as the non-woven fabric,
the composite material can be provided with the heat conducting
properties in a thickness direction thereof.
[0139] Accordingly, in the case of a molded body such an antenna
that uses the composite material shown in, for instance, FIG. 1,
also in a thickness direction thereof, excellent heat conducting
properties can be established.
[0140] Furthermore, when an electrically insulating non-woven
fabric is used as the non-woven fabric, when the triaxial woven
opening.
[0141] The electric wave reflectance depends largely on a magnitude
of the opening, as the frequency becomes higher, unless the opening
is made smaller, the more the electric wave goes through, resulting
in lowering the electric wave reflectance.
[0142] In order to cope with higher frequencies exceeding a limit
to the electric wave reflection due to the triaxial woven fabric
alone, a conductive non-woven fabric having functionality higher in
the electric wave reflectance is laminated.
[0143] The non-woven fabric (functional non-woven fabric), without
damaging the characteristics of the triaxial woven fabric, enables
to enhance (or give) the functionality such as the electrical,
thermal performances.
[0144] Processes until a molded body is obtained from the fiber
base material such as the triaxial woven fabric will be generally
explained. As the method by which a molded body is obtained from
the composite material according to the embodiment, there are, for
instance, the following three methods.
[0145] (Autoclave Molding, Vacuum Bag Molding)
[0146] 1. Fiber base material.fwdarw.prepreg (impregnation .cndot.
semi-curing).fwdarw.lay-up (giving a form on a mold).fwdarw.molding
(curing).fwdarw.molded body.
[0147] (RTM Molding)
[0148] 2. Fiber base material.fwdarw.preform (setting in a
mold).fwdarw.molding (resin injection .cndot. curing).fwdarw.molded
body.
[0149] (Hand Lay-Up Molding)
[0150] 3. Fiber base material.fwdarw.lay-up (giving a form on a
mold with a resin impregnating .cndot. curing).fwdarw.molded
body.
[0151] [Characteristics of Composite Material]
[0152] In one embodiment of a composite material according to the
invention, the electrical characteristics such as the electrical
conducting properties, the electrical insulating properties, the
heat conducting properties, the heat insulating properties and the
electric wave reflecting properties are controlled with the
non-woven fabric.
[0153] That is, the electrical conducting properties, the
electrical insulating properties, the heat conducting properties,
the heat insulating properties and the electric wave reflecting
properties can he controlled with the kind of the fiber given to
the non-woven fabric, a filament diameter of the fiber, and density
(it is controlled by varying voids and a thickness).
[0154] For instance, the heat conducting properties of one
embodiment of the composite material according to the invention can
be controlled with a material that is used in the non-woven fabric.
However, the electrical conducting non-woven fabrics high in the
electrical conducting properties are in many cases the heat
conducting non-woven fabrics high in the heat conducting
properties.
[0155] That is, the non-woven fabric that is used in the composite
material according to the embodiment can be considered a heat
conducting non-woven fabric, a heat insulating non-woven fabric, an
electrical conducting non-woven fabric, an electrical insulating
non-woven fabric, a heat conducting and electrical conducting
non-woven fabric, a heat conducting and electrical insulating
non-woven fabric, a heat insulating and electrical conducting
non-woven fabric, and a heat insulating and electrical insulating
non-woven fabric.
[0156] According to the characteristics of these non-woven fabrics,
the characteristics of one embodiment of the composite material
according to the invention are determined.
[0157] Furthermore, to the acoustic vibration when a rocket is
launched, these non-woven fabrics, having voids therein similarly
to the triaxial woven fabrics, are light and can stand up to
stronger acoustic vibrations.
[0158] Still furthermore, as the structure and shape of the
non-woven fabric, for instance, in the electrical conducting
non-woven fabric, the non-woven fabric made of metal fiber or
metallized fiber, or the metallized non-woven fabric obtained by
depositing a metal on the non-woven fabric can take a
three-dimensionally free shape.
[0159] Accordingly, the non-woven fabric and the triaxial woven
fabric are laminated and, without completely curing the resin, a
prepreg can be formed.
[0160] Furthermore, the non-woven fabric and the triaxial woven
fabric can be laminated to form a composite material.
[0161] Still furthermore, to a composite material made of a resin
and the triaxial woven fabric, a non-woven fabric can be stuck.
[0162] When a composite material that is formed into a lamination
structure by interposing the non-woven fabric between the triaxial
woven fabrics is molded, one that does not warp and peel, can be
superposed and pasted, and can be formed into three-dimensional
curved surfaces can be obtained. Accordingly, disadvantages in the
molding properties in the metal foils can be overcome.
[0163] Furthermore, since the composite material simultaneously
works as a supporter of the non-woven fabric and a structural
material, large mechanical strength and elastic modulus can be
maintained.
[0164] A structure in which the triaxial woven fabrics and the
non-woven fabric are thus molded into one body is large in the
spring-back properties by which, even after temporarily bent and
deformed owing to application of load stress, when the stress is
removed, the structure restores its original shape.
[0165] The characteristics are very preferable in the antenna
reflector boarded on an artificial satellite and so on.
[0166] In addition, even when the prepreg of the triaxial woven
fabric impregnated with the resin is made extremely thinner to an
extent of a substantial film, its shape can be maintained in space
without the atmosphere. Accordingly, appreciably lighter weights
can be achieved.
[0167] (Embodiments)
[0168] In the following, a specific structure of a molded body in
which a composite material according to the invention is employed
will be explained as embodiments. Here, a parabolic antenna
reflector is adopted as a molded body according to the invention.
In addition, as the non-woven fabric an electrical conducting
non-woven fabric is used.
[0169] Embodiment 1
[0170] A sintered non-woven fabric in which copper fibers having a
filament diameter of 16 .mu.m are used and that has the porosity of
53.3% is pasted on a surface of a triaxial woven fabric prepreg
that is obtained by weaving 135tex glass fibers according to a
Basic weave with the weave density of 9.25 threads/inch and by
impregnating with epoxy resin. With this configuration, a reflector
for use with a 350 mm diameter parabolic antenna for use in 12 GHz
frequency band is experimentally prepared.
[0171] When a BS airwave of 11.84256 GHz is actually measured
through an amplifier with a spectrum analyzer, the receiving
intensity is -53.17 dB.
[0172] It is found that the reflector has such a light weight as 31
g, different from a metal reflector, does not structurally exhibit
the plastic deformation due to an external load, has the
spring-back function and is excellent in the shape-sustaining
properties.
[0173] In the 180-degree peel test, material destruction of the
copper fiber sintered non-woven fabric does not accompany the
peeling.
[0174] In the thermal shock test from +180 degree centigrade in an
oven to -195 degree centigrade in liquid nitrogen, the copper fiber
sintered non-woven fabric does not peel off the triaxial woven
fabric composite material.
[0175] Embodiment 2
[0176] A sintered non-woven fabric in which stainless steel fibers
having a single fiber diameter of 8 .mu.m are used and that has the
porosity of 18.2% is interposed between triaxial woven fabric
prepregs that are obtained by weaving 11tex PBO fibers according to
a Basic weave with the weave density of 18.5 threads/inch and by
impregnating with cyanate ester resin. With this configuration, a
reflector for use with a 350 mm diameter parabolic antenna for use
in 12 GHz frequency band is experimentally prepared.
[0177] When a BS airwave of 11.84256 GHz is actually measured
through an amplifier with a spectrum analyzer, the receiving
intensity is -53.57 dB.
[0178] It is found that the reflector has such a light weight as 18
g, different from a metal reflector, does not structurally exhibit
the plastic deformation due to an external load, has the
spring-back function and is excellent in the shape-sustaining
properties.
[0179] In the 180-degree peel test, material destruction of the
stainless steel fiber sintered non-woven fabric does not accompany
the peeling.
[0180] In the thermal shock test from +180 degree centigrade in an
oven to -195 degree centigrade in liquid nitrogen, the stainless
steel fiber sintered non-woven fabric does not peel off the
triaxial woven fabric composite material.
[0181] Comparative Embodiment 1
[0182] With 1 mm thick aluminum, a reflector for use with a 360 mm
diameter parabolic antenna for use in 12 GHz frequency band is
experimentally prepared.
[0183] When a BS airwave of 11.84256 GHz is actually measured
through an amplifier with a spectrum analyzer, the receiving
intensity is -53.15 dB. It weighs 316 g.
[0184] Comparative Embodiment 2
[0185] A copper foil having a thickness of 30 .mu.m is pasted on a
surface of a triaxial woven fabric prepreg that is obtained by
weaving 135tex glass fibers according to a Basic weave with the
weave density of 9.25 threads/inch and by impregnating with epoxy
resin. With this configuration, a reflector for use with a 350 mm
diameter parabolic antenna for use in 12 GHz frequency band is
experimentally prepared.
[0186] In a draping pattern in which the copper foil is divided
into less than 12 divisions, the copper foils cannot fit well into
a three-dimensional curved surface, resulting in a wrinkled
reflector poor in a mirror surface accuracy.
[0187] It weighs 55 g, and after bending owing to own weight, it
cannot spontaneously restore its original shape through the plastic
deformation.
[0188] In the 180-degree peel test, the copper foil is peeled, and
it is found that the peel strength is such low as 0.093 kN/m or
less.
[0189] With a sample after the thermal shock test, the peel test is
carried out. It is found that the peel strength is further
deteriorated to 0.056 kN/m or less.
[0190] Comparative Embodiment 3
[0191] With a non-woven fabric simple body configuration in which a
non-woven fabric that uses aramid fibers having a single fiber
diameter of 12 .mu.m and has the porosity of 17.3% is copper-plated
by a thickness of 5 .mu.m followed by impregnating with cyanate
ester resin, a reflector for use with a 350 mm diameter parabolic
antenna for use in 12 GHz frequency band is experimentally
prepared.
[0192] Although since it is formed of the non-woven fabric simple
body, it weighs only 5 g, it is low in the tearing strength and the
stiffness, and deficient in the spring-back properties. It is found
that maintaining dimensional precision is difficult.
[0193] In the above embodiments, as the electric conducting
non-woven fabric, the non-woven fabric made of copper fibers and
the non-woven fabric made of stainless steel fibers are used, and
as the composite material containing the triaxial woven fabric, the
glass fibers impregnated with epoxy resin and PBO impregnated with
cyanate ester resin are used. However, the configurations of the
composite materials according to the invention are not restricted
to the above.
[0194] As materials constituting the electrical conducting
non-woven fabric, metal fibers such as copper, silver, gold and
stainless steel fiber sintered non-woven fabrics (in order to
inhibit the performance from deteriorating owing to corrosion of
the metal, gold or silver may be formed according to wet plating,
vacuum-deposition or sputtering), or ones in which fibers made of
appropriate materials such as aramid, PBO, glass, and carbon fiber
are metal plated, or like a copper plated aramid fiber non-woven
fabric ones in which the non-woven fabric made of aramid, PBO,
glass or carbon fiber is metal plated may be used.
[0195] Thus, the material of the fiber is not questioned when the
fiber has the electrical conducting properties and can be formed
into the non-woven fabric.
[0196] Furthermore, as the non-woven fabric, copper plated aramid
fiber non-woven fabric (weight: 38 g/m.sup.2, plating thickness: 5
.mu.m, porosity: 17%) can be used.
[0197] Such non-woven fabrics, in comparison with the non-woven
fabrics 100% made of the metal fibers, are lighter in weight,
higher in the mechanical strength, smaller in the thermal expansion
coefficient, less in deterioration in the functionality after
folding, easier in cutting, and can be finished into an excellent
cross section.
[0198] Furthermore, such non-woven fabrics, being highly reflective
even in a millimeter wave region, can be also applied to, other
than the reflector and the ground conductor, elements such as patch
and slot.
[0199] Furthermore, as the non-woven fabric, copper fiber sintered
non-woven fabric (weight: 50 g/m.sup.2, fiber diameter: 16 .mu.m,
porosity: 53%) can be used.
[0200] Such non-woven fabric, being 100% made of metal, is high in
the heat resistance, free from care of out-gassing, flexible and
small in the electrical resistance.
[0201] Furthermore, as the non-woven fabric, carbon fiber non-woven
fabric (weight: 10 g/m.sup.2, fiber diameter: 8 .mu.m, porosity:
27%) can be used.
[0202] Such non-woven fabric, being carbon fiber, is electrical
conducting, and furthermore super-light in weight and small in the
thermal expansion coefficient.
[0203] When such non-woven fabric is combined with the triaxial
woven fabric in which the carbon fiber is used, with excellent
properties of the triaxial woven fabric maintaining as it is,
electric wave reflecting properties at higher frequencies can be
obtained.
[0204] Furthermore, in the embodiments, as the materials that endow
the molded body with the mechanical properties, an example of the
triaxial woven fabric made of the glass and PBO fiber is cited.
[0205] The composite materials according to the embodiments are
common to the fiber-reinforced resin composite materials in the
mechanical properties such as the mechanical strength of the molded
body, stiffness and the spring-back properties that enable to
restore the original shape against the stress.
[0206] When the material of the molded body is properly selected,
the molded body can be tailored to applications.
[0207] In particular, the composite material made of a triaxial
woven fabric that uses continuous fibers is preferable.
[0208] In addition, when the molded body is formed into a triaxial
woven fabric structure, owing to the structural symmetry thereof,
the molded shape is deformed with difficulty against the
temperature variation and load of mechanical stress. Furthermore,
since when these loads are removed, the original design shape can
be restored, the shape stability is excellent.
[0209] As the fibers that can be used with the triaxial woven
fabrics, aramid, PBO, glass, and carbon fiber can be cited. As the
structure thereof, a 16 to 64 gage basic weave or bi-plain weave
pattern triaxial woven fabric structure can be adopted.
[0210] Furthermore, as the fibers that are used in the triaxial
woven fabrics, 64 gage basic weave pattern triaxial woven fabric in
which PBO fibers having the fineness of 11 tex (weight: 26
g/m.sup.2, weave density: 18.5 threads/in) can be also used.
[0211] The triaxial woven fabric, being made of the PBO fiber, is
high in the mechanical strength, high in the elastic modulus, high
in the heat resistance, negative in the thermal expansion
coefficient, electric wave-transmissive, such slender in the
fineness as 11 tex, such thin in a fabric thickness as 60 .mu.m,
such super-light in the weight as 26 g/m.sup.2, and such high in
the weave density as 18.5 threads/in, resulting in higher surface
finishing accuracy and higher adherence with the non-woven
fabric.
[0212] Furthermore, since such triaxial woven fabrics can be easily
folded and the triaxial woven fabric simple body is electric
wave-transmissive, the physical properties are not deteriorated
owing to the folding.
[0213] Still furthermore, although as the matrix resin, epoxy
resin, cyanate ester resin and so on can be cited, the matrix resin
is selected according to the advisability of the combination with
the triaxial woven fabric and objects, and is not necessarily
restricted to these.
[0214] For instance, as the resin, high temperature curable epoxy
resin and cyanate ester resin (curing temperature: 180 degree
centigrade, cure period: 2 hours, molding pressure: 0.6 MPa) can be
used.
[0215] The resins used in the invention, when the molded body is
intended to use as, for instance, a space structure, are ones that
are suitable for a space environment, and when there is no problem
in the adherence, there is no particular restriction.
[0216] A combination structure of the non-woven fabric and the
triaxial woven fabric may be any one of that in which the non-woven
fabric is pasted to the triaxial woven fabric, or that in which the
triaxial woven fabrics and the non-woven fabric are laminated with
the non-woven fabric interposed between the triaxial woven
fabrics.
[0217] Furthermore, triaxial woven fabrics made of two or more
kinds of different materials and the non-woven fabric may be
laminated with the non-woven fabric interposed between the triaxial
woven fabrics.
[0218] Still furthermore, the triaxial woven fabric and the
non-woven fabric are laminated and thereafter may be plated.
[0219] Furthermore, the triaxial woven fabric may be a prepreg
impregnated with a resin.
[0220] Still furthermore, the invention can be applied to the
molded bodies such as the reflector of the parabolic antenna, the
element and ground conductor of the slot antenna, the element, the
ground conductor and a micro-strip line of the patch antenna, the
solar battery paddle of the artificial satellite, and the bus
(structure) of the artificial satellite and so on.
[0221] When the molded body is used in, for instance, an antenna
for use in space, an antenna that is storable, expandable, and high
in the performance can be obtained.
INDUSTRIAL APPLICABILITY
[0222] As explained above, according to the invention, the
following excellent advantages can be achieved.
[0223] Since the non-woven fabric does not cause the peeling and
the wrinkle, including complicated three-dimensional shapes, the
structure can be freely designed.
[0224] When the electrical conducting non-woven fabric is used as
the non-woven fabric, in the electrical conducting non-woven
fabric, since kinds of metals and fibers, and the filament
diameters and single fiber diameters can be freely selected, the
electrical conducting properties, the reflectance, the porosity,
the thickness and the weight can be freely controlled.
[0225] Furthermore, when a surface of the electrical conducting
non-woven fabric is processed smooth, mirror surface precision can
be improved, resulting in further improving the reflectance.
[0226] When the non-woven fabric having the heat conducting
properties is used as the non-woven fabric, a thickness direction
of the molded body in which the composite material is used such as
the antenna reflector can be endowed with the heat conducting
properties.
[0227] When a heat insulating non-woven fabric is used as the
non-woven fabric, with a simple structure, the temperature
fluctuation in the members of an artificial satellite can be
alleviated.
[0228] When an electrical insulating non-woven fabric is used as
the non-woven fabric, a layout of circuits and various kinds of
devices on the composite material can be easily designed.
[0229] Since the triaxial woven fabric is assigned to the dimension
stability and the strength properties and the non-woven fabric is
assigned to the functionality such as the electrical conducting
properties, the reflecting properties, and the heat conducting
properties and so on, by combining the respective materials and
structures, designs appropriate for applications and conditions can
be realized.
[0230] The triaxial woven fabric and non-woven fabric, being
pseudo-isotropic in planes, are functionally less influenced by
temperature fluctuations and the stress loads. Accordingly, lighter
structural materials can be obtained.
[0231] The triaxial woven fabric and non-woven fabric, having void
portions therein, can stand up to the sound and vibration at the
rocket launch.
[0232] According to the invention, the materials most preferable
for the functional structure materials for use with the artificial
satellite that combine the excellent dimensional stability, the
pseudo-isotropy, the light weight, the high elastic modulus, the
high heat conducting properties and the high reflecting properties
can be obtained.
[0233] Furthermore, since the composite material is formed by
laminating the non-woven fabric having the heat conducting
properties or the heat insulating properties with the triaxial
woven fabric, when the composite material is used, the heat control
can be easily and as far as necessary applied to necessary portions
of the device (for instance, devices for use with the artificial
satellite) according to the existing manufacturing method.
[0234] In the triaxial woven fabric, the weave structure generates
hexagonal through holes that interconnect front and rear surfaces
thereof. Accordingly, when the structure where the electrical
conducting non-woven fabrics sandwich the front and rear surfaces
of the triaxial woven fabric is taken, the electrical conducting
non-woven fabrics on the front and rear surfaces can be mutually
electrically connected, and thereby can be functioned as an
electrical conductor of one body. According to the lamination
structure, the mechanical strength and the electrical
characteristics can be accentuated.
[0235] The invention can be applied to, including electric circuit
substrate, radiation elements, reflecting surfaces and so on of the
various kinds of antennas.
[0236] According to the invention, the line antennas such as the
parabolic antennas and dipole antennas and so on, or planar
antennas and so on such as patch antennas and so on are excellent
in the electrical properties and very light in the weight, being
high in the elastic modulus to the stress, exhibit the spring-back
function even under large stress to restore its original shape
without undergoing the plastic deformation. Accordingly, these can
be applied under various circumstances.
* * * * *