U.S. patent application number 09/781321 was filed with the patent office on 2001-08-16 for fluid-impermeable composite hose.
Invention is credited to Niki, Nobuaki, Noba, Kunihiro, Takagi, Yuji.
Application Number | 20010013374 09/781321 |
Document ID | / |
Family ID | 18566445 |
Filed Date | 2001-08-16 |
United States Patent
Application |
20010013374 |
Kind Code |
A1 |
Niki, Nobuaki ; et
al. |
August 16, 2001 |
Fluid-impermeable composite hose
Abstract
A fluid-impermeable composite hose has a wall including a
laminated layer formed by longitudinally lapping a laminated sheet
which contains a metallic foil, or a metallic layer formed by vapor
deposition. The laminated layer is bound with thread wound about it
at a density not exceeding 20%, and bound to an extent forming
constrictions therein if required. The thread prevents the
deformation in cross section of the hose and the separation of the
overlapping edge portions of the laminated sheet which might
otherwise be caused by the bending resistance of the laminated
sheet. The constrictions improve the flexibility of the hose.
Inventors: |
Niki, Nobuaki; (Inuya-shi,
JP) ; Noba, Kunihiro; (Nagoya-shi, JP) ;
Takagi, Yuji; (Komaki-shi, JP) |
Correspondence
Address: |
JACOBSON HOLMAN PLLC
400 SEVENTH STREET N.W.
SUITE 600
WASHINGTON
DC
20004
US
|
Family ID: |
18566445 |
Appl. No.: |
09/781321 |
Filed: |
February 13, 2001 |
Current U.S.
Class: |
138/138 ;
138/126; 138/127; 138/143; 138/146 |
Current CPC
Class: |
F16L 11/085
20130101 |
Class at
Publication: |
138/138 ;
138/126; 138/143; 138/146; 138/127 |
International
Class: |
F16L 011/10 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 16, 2000 |
JP |
2000-043539 |
Claims
What is claimed is:
1. A fluid-impermeable composite hose having a wall comprising a
laminated layer formed of a laminated sheet which contains a
metallic foil, or a metallic layer formed by vapor deposition,
wherein the laminated layer is formed by longitudinally lapping a
tape of the laminated sheet, and is bound with thread wound about
it at a density not exceeding 20%.
2. The hose according to claim 1, wherein the laminated layer is
lined with a rubber layer and has constrictions formed by the
thread owing to the elastic deformation of the rubber layer.
3. The hose according to claim 2, wherein the constrictions have a
depth as defined by the thread cutting into an outer surface of the
laminated layer.
4. The hose according to claim 2, wherein its wall is sequentially
comprises a resin layer as its innermost layer, a first
intermediate rubber layer, the laminated layer, a second
intermediate rubber layer, a reinforcing layer and an outer rubber
layer as its outermost layer.
5. The hose according to claim 2, wherein its wall is sequentially
comprises an inner rubber layer as its innermost layer, the
laminated layer, an intermediate rubber layer, a reinforcing layer
and an outer rubber layer as its outermost layer.
6. The hose according to claim 2, wherein the constrictions are
formed by a tension of the thread and/or a dry heat contraction
thereof.
7. The hose according to claim 1, wherein the laminated layer is
bound with the thread while retaining a smooth outer surface
thereof.
8. The hose according to claim 7, wherein its wall sequentially
comprises a resin layer as its innermost layer, the laminated
layer, an intermediate rubber layer, a reinforcing layer and an
outer rubber layer as its outermost layer.
9. The hose according to claim 7, wherein its wall sequentially
comprises a resin layer as its innermost layer, the laminated
layer, another resin layer, an intermediate rubber layer, a
reinforcing layer and an outer rubber layer as its outermost
layer.
10. The hose according to claim 1, wherein the laminated sheet has
a pair of lateral edge portions overlapping each other and joined
to each other adhesively or by fusion under heat.
11. The hose according to claim 1, wherein the thread comprises:
(1) a single thread wound spirally; (2) two or more threads wound
spirally in the same direction; (3) two threads wound spirally in
the opposite directions; or (4) two or more sets of two or more
threads each wound spirally in the opposite directions.
12. The hose according to claim 1, wherein the thread has a
thickness of 100 to 3000 deniers and a tensile strength of 5 to 500
N.
13. The hose according to claim 1, wherein the thread is of fibers
selected from the group consisting of PET, PA, rayon, aramid, PEN
and polyvinyl alcohol fibers.
14. The hose according to claim 1, wherein the laminated sheet
comprises (1) a metallic foil, (2) a combination of a metallic foil
and a reinforcing material, or (3) a metallic layer formed by vapor
deposition, and a resin film or films laminated thereon.
15. The hose according to claim 14, wherein the laminated sheet
comprises the foil, or the combination of the foil and the
reinforcing material, and a pair of resin films holding it
therebetween and joined together adhesively or by fusion.
16. The hose according to claim 14, wherein the laminated sheet
comprises the metallic layer formed by vapor deposition on one side
of a first resin film, and a second resin film joined to that side
of the first resin film adhesively or by fusion.
17. The hose according to claim 14, wherein the reinforcing
material is a wire mesh or a reinforcing fabric.
18. The hose according to claim 1, adapted to be used in a motor
vehicle.
19. The hose according to claim 2, adapted to be used as a fuel
hose.
20. The hose according to claim 7, adapted to be used as a hose for
a carbon dioxide refrigerant.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a fluid-impermeable composite
hose. More particularly, it relates to a fluid-impermeable
composite hose having a fluid-impermeable laminated layer formed of
a laminated sheet containing a metallic foil, or a metallic layer
formed by vapor deposition. The hose of this invention is
particularly useful as a fluid-impermeable hose for transporting
any of various kinds of fluids in a motor vehicle.
[0003] 2. Description of the Related Art
[0004] Every hose used for transporting a refrigerant in an
air-conditioning system on a motor vehicle is required to be
impermeable to the refrigerant. This is particularly the case with
any hose for transporting e.g. an alternative to
chlorofluorocarbons, or carbon dioxide as a refrigerant in view of
system maintenance, environmental protection, etc. One of the most
effective approaches is a hose having a laminated wall layer
containing a metallic foil, or a metallic layer formed by vapor
deposition. Environmental protection also requires a fuel hose to
be impermeable to fuel, and a laminated wall layer is very useful
for a fuel hose, too.
[0005] It has been usual to form a laminated wall layer for a hose
by longitudinal lapping or spiral winding of a tape of a laminated
sheet containing a metallic foil, or a metallic layer formed by
vapor deposition. Longitudinal lapping is a method in which a tape
of a laminated sheet having a width large enough to encircle a hose
to be made is placed in parallel to the longitudinal axis of the
hose and bent into a cylindrical layer having a pair of overlapping
edge portions. Spiral winding is a method in which a tape of a
laminated sheet is wound in a spirally overlapping way to form a
cylindrical layer.
[0006] Longitudinal lapping has a number of advantages over spiral
winding, as stated below. First, a cylindrical layer can be formed
more rapidly by longitudinal lapping. Then, it can be carried out
in tandem with a step of rubber extrusion preceding or following
it. Moreover, the overlapping edge portions formed by longitudinal
lapping have a smaller length which means that a hose has a higher
fluid impermeability.
[0007] A laminated sheet is, however, a multilayer structure having
spring elasticity. While it does not exhibit a very high bending
resistance for spiral winding, it exhibits a high bending
resistance for longitudinal lapping as it has to be bent across its
width. Its bending resistance tends to cause the separation of the
overlapping edge portions from each other. As a result, it is
likely that a hose having a layer formed by longitudinal lapping
may not retain an accurately circular shape in cross section, but
may have a deformed circular shape. Moreover, the separation of the
overlapping edge portions joined together may result in the failure
of the hose to retain its fluid impermeability. Even if an
intermediate rubber layer, or a thin resin layer may be extruded
about the laminated layer, its binding force is not sufficiently
strong to overcome the bending resistance of the laminated
sheet.
[0008] Moreover, a hose having a laminated layer formed by
longitudinal lapping is less easy to bend, since the overlapping
edge portions of the laminated sheet extend longitudinally of the
hose. In other words, it is usually inferior in overall flexibility
to any hose having a spirally wound wall layer.
SUMMARY OF THE INVENTION
[0009] It is, therefore, an object of this invention to overcome
those drawbacks of any fluid-impermeable composite hose having a
fluid-impermeable laminated layer formed by longitudinal lapping of
a tape of a laminated sheet which are due to the high bending
resistance of the overlapping edge portions of the laminated sheet,
as pointed out above. It is another object of this invention to
improve the overall flexibility of any such fluid-impermeable
composite hose.
[0010] The inventors of this invention have found that it is
effective to bind a longitudinally lapped tape of a laminated sheet
by winding thread about it at a low density. The inventors have
also found that it is effective to line a laminated layer with a
rubber layer and rely upon its elastic deformation for causing the
strong binding force of the wound thread to make constrictions in
the laminated layer.
[0011] According to a first aspect of this invention, there is
provided a fluid-impermeable composite hose having a wall
comprising a laminated layer formed of a laminated sheet which
contains a metallic foil, or a metallic layer formed by vapor
deposition, wherein the laminated layer is formed by longitudinally
lapping a tape of the laminated sheet, and is bound with thread
wound about it at a density not exceeding 20%. The high bending
resistance of the laminated sheet is effectively suppressed by the
thread wound about it. Therefore, there is no deformation of the
hose in its cross sectional shape. Moreover, there is no separation
of the overlapping edge portions of the laminated layer which may
cause the loss of the fluid impermeability of the hose.
[0012] The thread is essentially different in construction and
effect from any reinforcing yarn layer formed usually on a hose.
The reinforcing yarn layer is intended for improving the strength
of the hose. It is formed of reinforcing yarn wound spirally or
braided at a high density, even though it may lower the flexibility
of the hose to some extent or other. On the other hand, the thread
employed according to this invention is wound only at a density not
exceeding 20%, and does not lower the flexibility of the hose. It
is exclusively intended for suppressing the bending resistance of
the laminated layer, and its density not exceeding 20% is
sufficient for that purpose.
[0013] According to a second aspect of this invention, there is
provided a rubber layer on an inner periphery of the laminated
layer, and the laminated layer has constrictions formed by the
thread owing to the elastic deformation of the rubber layer. The
constrictions make the hose easier to bend and improve its
flexibility. If the thread is wound at a high density, the
constrictions do not have a sufficiently large depth to improve the
flexibility of the hose effectively. The thread density not
exceeding 20% is, however, low enough to ensure that the
constrictions have a sufficiently large depth to improve the
flexibility of the hose effectively. The constrictions are very
unlikely to cause e.g. the fracture of the metallic foil in the
laminated layer unless the hose is repeatedly subjected to an
extremely high pressure or large displacement. Thus, the hose is
particularly suitable for use as, for example, a fuel hose which is
unlikely to be subjected to a high pressure or a large
displacement.
[0014] According to a third aspect of this invention, the
constrictions are formed by the tension of the thread and/or its
dry heat contraction. These are particularly effective ways of
forming the constrictions. The constrictions formed by the tension
of the thread are formed when it is wound, while those formed by
its dry heat contraction are formed when the hose is heated as for
curing.
[0015] According to a fourth aspect of this invention, the
laminated layer has a smooth outer surface not having any
constriction formed by the thread. Such a laminated layer is
particularly unlikely to have its metallic foil broken when the
hose is repeatedly subjected to a high pressure or a large
displacement, though it cannot be expected to give the hose any
such improved flexibility as is given by the constrictions in the
second aspect of this invention. Thus, the hose is particularly
suitable for use as a refrigerant hose which is very likely to be
repeatedly subjected to a high pressure, or a large displacement,
especially a hose for a carbon dioxide refrigerant. The laminated
layer is preferably lined with a layer of a resin, or any other
hard material which is not easily deformable, while the thread is
preferably of a material having only a low degree of dry heat
contraction, so that the laminated layer may retain a smooth outer
surface, while the thread can bind the laminated layer strongly
enough to overcome the bending resistance of its overlapping edge
portions joined together.
[0016] According to a fifth aspect of this invention, the thread is
preferably of polyethylene terephthalate (PET), polyamide (PA),
rayon, aramid (aromatic polyamide), polyethylene naphthalate (PEN),
or polyvinyl alcohol fibers.
[0017] The thread for binding the laminated layer may be of any
kind, however, it is desireable to use the thread of PET, PA,
rayon, aramid, PEN, or polyvinyl alcohol fibers as in the fifth
aspect.
[0018] According to a sixth aspect of this invention, the laminated
sheet is preferably composed of a resin film laminated on (1) a
metallic foil, (2) a metallic foil and a reinforcing material, or
(3) a metallic layer formed by vapor deposition. The combination of
a metallic foil and a reinforcing material is particularly
preferred for the laminated layer having constrictions formed
therein.
[0019] The above and other features and advantages of this
invention will become more apparent from the following description
and the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a partly cutaway perspective view of a
fluid-impermeable composite hose embodying this invention;
[0021] FIG. 2 is a partly cutaway perspective view of another
example of a fluid-impermeable composite hose embodying this
invention;
[0022] FIG. 3 is a partly cutaway perspective view of still another
example of a fluid-impermeable composite hose embodying this
invention;
[0023] FIG. 4A is a partly cutaway perspective view of a part of a
laminated sheet;
[0024] FIG. 4B is a cross-sectional view of the laminated sheet
shown in FIG. 4A; and
[0025] FIG. 4C is a view similar to FIG. 4B, but showing another
example of a laminated sheet.
DETAILED DESCRIPTION OF THE INVENTION
[0026] Use of Fluid-impermeable Composite Hoses:
[0027] The fluid-impermeable composite hose of this invention is
useful as a hose for transporting any of various kinds of fluids.
It is particularly suitable as a hose for a refrigerant or fuel,
and still more suitable for use in a motor vehicle because of its
flexibility to withstand any vibration of a running vehicle or its
engine.
[0028] The hose according to the fourth aspect of this invention,
which has no constriction in its laminated wall layer, is, for
example, suitable as a hose for a carbon dioxide refrigerant
because of its durability to withstand a large displacement or a
repeatedly applied high pressure. The hose according to the second
aspect of this invention, which has constrictions, is suitable
because of its flexibility as, for example, a fuel hose which is
not subjected to a very large displacement or a very high
pressure.
[0029] Wall Construction of Hoses:
[0030] According to an essential feature of this invention, the
fluid-impermeable composite hose has in its wall a laminated layer
formed by longitudinally lapping a tape of a laminated sheet and
bound with thread wound about it at a density not exceeding 20%.
There is no particular limitation as to any other layer of its
wall, or the position of the laminated layer relative to the other
layers.
[0031] There are, however, four preferred combinations of wall
layers as shown at (a) to (d) below. The layers are shown
sequentially from the radially innermost one.
[0032] (a) A resin layer/an intermediate rubber layer/a laminated
layer/an intermediate rubber layer/a reinforcing layer/an outer
rubber layer;
[0033] (b) A rubber layer/a laminated layer/an intermediate rubber
layer/a reinforcing layer/an outer rubber layer;
[0034] (c) A resin layer/a laminated layer/an intermediate rubber
layer/a reinforcing layer/an outer rubber layer; and
[0035] (d) A resin layer/a laminated layer/a resin layer/an
intermediate rubber layer/a reinforcing layer/an outer rubber
layer.
[0036] Both of the hoses as shown at (a) and (b) have a rubber
layer located immediately inwardly of their laminated layer. It is
preferable to bind the laminated layer of each of these hoses with
thread so strongly as to form constrictions in that layer, though
it is alternatively possible to bind the layer with thread to the
extent not forming any such constriction. The constrictions make
the hose flexible enough to be suitable as, for example, a fuel
hose. The hose as shown at (a) is particularly high in fuel
impermeability owing to the innermost resin layer of its wall.
[0037] Both of the hoses as shown at (c) and (d) have a resin layer
located immediately inwardly of their laminated layer. Each of
these hoses is easy to bind with thread, while retaining a smooth
outer surface on its laminated layer, since the resin layer is not
easily deformable. Thus, they are suitable as highly durable hoses
for transporting a refrigerant, particularly a highly permeant one,
such as carbon dioxide. The hose as shown at (d) is particularly
strong in the metallic foil in the laminated layer, since the layer
is secured and protected between the inner and outer resin
layers.
[0038] Laminated Layer:
[0039] The laminated layer is formed by longitudinally lapping a
tape of a laminated sheet containing a metallic foil, or a metallic
layer formed by vapor deposition, and is bound with thread wound
about it at a density not exceeding 20%. The thread keeps the
joining portions of the laminated sheet from projecting radially
outwardly and thereby holds the hose substantially circular in
cross section.
[0040] The laminated sheet applied by longitudinal lapping
preferably has a pair of widthwise edge portions overlapping each
other to some extent. The overlapping edge portions are preferably
joined to each other with an adhesive or a layer of an adhesive
material, or by fusion under heat.
[0041] The thread can be wound in any way if it can bind the
laminated layer effectively. For example, a single thread may be
wound spirally. Two or more threads may be wound spirally in the
same direction. Two threads may be wound spirally in the opposite
directions in which they cross each other. Two or more sets of two
or more threads each may be wound spirally in the opposite
directions. The thread (or threads) is preferably bonded to the
laminated layer by any appropriate method, but may not be bonded.
The thread may be of any thickness and material if it is
sufficiently high in tensile strength and durability to exert a
satisfactory binding force on the laminated layer. For example,
however, it is suitable to use a thread having a thickness of, say,
100 to 3000 deniers and a tensile strength of, say, 5 to 500 N.
[0042] Referring to the binding force of the thread, it may be at
least large enough to keep the overlapping edge portions of the
laminated sheet from projecting radially outwardly of the hose
according to the fourth aspect of this invention. As regards the
hose according to the second aspect of this invention, the force
may be at least large enough to form constrictions in the laminated
layer. The force cannot be expressed by any specific numerical
value, since it depends on the hardness of the laminated sheet, the
diameter of the laminated layer, the softness of the rubber layer
in the hose according to the second aspect of this invention,
etc.
[0043] The thread may be of any material including PET, PA, rayon,
aramid, PEN and polyvinyl alcohol fibers. It is, however,
preferably of PET or PA fibers having a relatively high degree of
heat contractibility to form constrictions in the laminated layer,
or of aramid fibers having a relatively low degree of heat
contractibility to maintain a smooth outer surface on the laminated
layer.
[0044] The magnitude (or depth) of the constrictions to be formed
in the laminated layer depends on the flexibility required of the
hose. Therefore, it cannot be defined by any specific numerical
value. They are, however, preferably of a depth formed by the
thread slightly cutting into the outer surface of the laminated
layer, or any greater visually recognizable depth.
[0045] Laminated Sheet:
[0046] The laminated sheet forming the laminated layer is in the
form of a tape containing a metallic foil, or a metallic layer
formed by vapor deposition. It is preferably formed by laminating a
resin film or films on (1) a metallic foil, (2) a combination of a
metallic foil and a reinforcing material, or (3) a metallic layer
formed by vapor deposition.
[0047] A laminated sheet containing a metallic foil, or a
combination thereof with a reinforcing material is usually formed
by sandwiching it between two resin films, and bonding them
together adhesively or by fusion. A laminated sheet containing a
metallic layer formed by vapor deposition can be formed by forming
a metallic layer by vapor deposition on one side of a resin film,
and bonding another resin film to that side. A laminated sheet may
also be formed by forming a metallic layer by vapor deposition on
one side of each of two resin films, and bonding the films together
on their sides carrying the metallic layers.
[0048] The reinforcing material does not necessarily have to be
bonded to the metallic foil, but can reinforce the foil more
effectively if it is bonded. The reinforcing material is preferably
located radially outwardly of the metallic foil. The metallic foil
and its reinforcing material may or may not be bonded to the resin
films.
[0049] The reinforcing material may be of any kind, but is
preferably one having a high stretch resistance and a high
flexibility. Preferred examples are a wire mesh and a reinforcing
fabric. The reinforcing fabric may be a canvas, or nonwoven fabric
formed preferably of e.g. aramid, carbon or glass fibers of low
stretchability. Another preferred example is a resin film of high
strength.
[0050] The thickness and hardness of the resin films, those of the
laminated sheet as a whole, etc. affect the bending resistance of
the laminated sheet formed by longitudinal lapping and the
flexibility of the hose. The resin films may be of any resin, but
are preferably of, for example, PA, PET or EVOH. These materials
are also preferred because of their high stretch resistance to
protect the metallic foil against fracture. The resin films
preferably have a thickness not exceeding, say, 100 .mu.m, and the
laminated sheet as a whole preferably has a thickness not
exceeding, say, 300 .mu.m.
[0051] Thin Resin Layer:
[0052] A resin layer in the form of a thin film may be formed
inwardly of the laminated layer, or outwardly thereof, too. The
resin layer formed inwardly of the laminated layer enables it to
retain a smooth outer surface despite the thread wound about it and
also improves the impermeability of the hose to a refrigerant, etc.
The resin layers formed both inwardly and outwardly secure and
protect the laminated layer in a sandwiched manner, as well as
improve the fluid impermeability of the hose. The resin layer (or
layers) is preferably of, for example, EVOH, PA or a mixture of PA
and a modified polyolefin, and has a thickness not exceeding, say,
300 .mu.m.
[0053] Intermediate Rubber Layer:
[0054] The intermediate rubber layer (or layers) provided in the
predetermined portion at the fluid-impermeable composite hose
serves to reduce or absorb any bending or deforming force acting
upon the hose, so that no such force may reach the laminated layer
and cause the metallic foil to break. The intermediate rubber layer
is preferably of a rubber material which is highly impermeable to a
refrigerant, etc., flexible, and easy to bond at a high temperature
to the laminated, or reinforcing layer. Preferred examples are
butyl rubber (IIR), halogenated IIR, ethylene-propylene rubber
(EPM), ethylene-propylene-diene rubber (EPDM) and nitrile rubber
(NBR). It preferably has a thickness of, say, 0.2 to 2.0 mm.
[0055] Reinforcing Layer:
[0056] The hose preferably has a reinforcing layer in its wall. The
reinforcing layer may, for example, be a braided wire layer, or a
layer formed by braiding reinforcing yarn, or winding reinforcing
yarn spirally, or in two spiral layers extending in the opposite
directions, or placing an intermediate rubber layer between two
such spiral layers.
[0057] Outer Rubber Layer:
[0058] An outer rubber layer may form the outermost wall layer of
the hose. It may be of any rubber of high weatherability, such as
chloroprene rubber (CR), IIR, chlorosulfonated polyethylene rubber
(CSM), EPDM or epichlorohydrin rubber (ECO).
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0059] Description will now be made of a few preferred embodiments
of this invention with reference to the drawings. Referring first
to FIG. 1, a fuel hose 1 has a resin layer 2 as the innermost layer
of its wall and a first intermediate rubber layer 3 formed about it
from IIR. The intermediate rubber layer 3 is surrounded by a
laminated layer 6 formed by longitudinally lapping a tape of a
laminated sheet 4 and bound with two threads 5 wound about it
spirally in the opposite directions. The threads 5 bind the
laminated layer 6 to an extent forming therein constrictions having
a certain depth, but not shown. The laminated layer 6 is surrounded
by a second intermediate rubber layer 7 of IIR, then a reinforcing
layer 8 formed by braiding an appropriate reinforcing yarn, and
finally an outer rubber layer 9 of EPDM.
[0060] FIG. 2 shows a fuel hose 10 having an inner rubber layer 11
formed from fluororubber (FKM), and surrounded by a laminated layer
6 formed as described above, an intermediate rubber layer 7 of NBR,
a reinforcing layer 8 and an outer rubber layer 9 of ECO.
[0061] FIG. 3 shows a hose 12 for a carbon dioxide refrigerant
having, outwardly of an inner resin layer 13 formed from a PA
resin, a laminated layer 14 formed by longitudinal lapping of a
tape of laminated sheet 4 and bound with threads 5 to an extent not
forming any constriction therein, and allowing the layer 14 to
retain a smooth outer surface. The laminated layer 14 is surrounded
by an intermediate rubber layer 7 of IIR, then a reinforcing layer
8 and finally an outer rubber layer 9 of EPDM.
[0062] The laminated sheet 4 is as shown in FIGS. 4A and 4B. It has
an inner resin layer 4a formed by a thin film of a thermoplastic
PET resin, a similar outer resin layer 4b, an aluminum foil 4c and
a reinforcing material 4d in the form of a resin sheet, the foil 4c
and the reinforcing material 4d being sandwiched between the inner
and outer resin layers. The resin layers 4a and 4b are greater in
width than the foil 4c and the reinforcing material 4d, and are
joined to each other along their lateral edges. The foil 4c is
bonded to the reinforcing material 4d with an adhesive not shown,
so that no tensile or like force acting upon the laminated sheet 4
may act upon the foil 4c held by the reinforcing material 4d.
[0063] FIG. 4C shows a modified form of laminated sheet 4. It does
not have any reinforcing material as shown at 4d above, but has
only a metallic foil 4c sandwiched between two resin layers 4a and
4b.
[0064] While the invention has been described by way of its
preferred embodiments, it is to be understood that variations or
modifications may be easily made by those skilled in the art
without departing from the scope of this invention which is defined
by the appended claims.
* * * * *