U.S. patent application number 10/618594 was filed with the patent office on 2004-01-22 for hose of impermeability and a process for manufacturing the same.
This patent application is currently assigned to Tokai Rubber Industries, Ltd.. Invention is credited to Hibino, Motoshige, Ikeda, Hidehito, Ikemoto, Ayumu, Ito, Hiroaki, Katayama, Kazutaka.
Application Number | 20040013836 10/618594 |
Document ID | / |
Family ID | 26582026 |
Filed Date | 2004-01-22 |
United States Patent
Application |
20040013836 |
Kind Code |
A1 |
Hibino, Motoshige ; et
al. |
January 22, 2004 |
Hose of impermeability and a process for manufacturing the same
Abstract
A hose of impermeability has a wall corrugated along at least a
part of its length, and formed by an inner thin resin layer, a
laminated layer including a metal film, or a layer formed by a
metal film, and an outer thin resin layer. It has a very high fluid
impermeability owing to its wall layer including or formed by a
metal film, and is also very flexible, capable of absorbing
vibration, light in weight and strong. A tubular inner thin resin
layer is formed by extrusion as the innermost layer of a
multi-layered hose wall, and a laminated tape including a metal
film, or simply a metal film is spirally wound or longitudinally
lapped about the inner resin layer. An outer thin resin layer is
formed about a layer formed by the laminated tape, or metal film,
and the whole is at least partly corrugated. Alternatively,
corrugation is done before an outer thin resin layer is formed by
electrostatic powder coating. A different process includes applying
a laminated tape including a metal film about a mandrel to form a
tubular laminated layer, and after removing the mandrel, coating
the inner surface of the tubular layer with a resin powder
electrostatically to form a thin resin layer thereon.
Inventors: |
Hibino, Motoshige;
(Minokamo-shi, JP) ; Katayama, Kazutaka;
(Komaki-shi, JP) ; Ikemoto, Ayumu; (Komaki-shi,
JP) ; Ikeda, Hidehito; (Kasugai-shi, JP) ;
Ito, Hiroaki; (Kasugai-shi, JP) |
Correspondence
Address: |
JACOBSON, PRICE, HOLMAN & STERN
PROFESSIONAL LIMITED LIABILITY COMPANY
400 SEVENTH STREET, N.W.
WASHINGTON
DC
20004
US
|
Assignee: |
Tokai Rubber Industries,
Ltd.
|
Family ID: |
26582026 |
Appl. No.: |
10/618594 |
Filed: |
July 15, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10618594 |
Jul 15, 2003 |
|
|
|
09739768 |
Dec 20, 2000 |
|
|
|
Current U.S.
Class: |
428/36.91 |
Current CPC
Class: |
F16L 11/15 20130101;
B29C 48/08 20190201; B29C 63/06 20130101; B29C 53/30 20130101; F16L
2011/047 20130101; B29C 53/58 20130101; F16L 11/24 20130101; F16L
11/11 20130101; B29L 2009/00 20130101; B29C 48/00 20190201; Y10T
428/1393 20150115; F16L 11/042 20130101; Y10T 156/1018
20150115 |
Class at
Publication: |
428/36.91 |
International
Class: |
B32B 001/08 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 27, 1999 |
JP |
11-368709 |
Mar 16, 2000 |
JP |
2000-079375 |
Claims
What is claimed is:
1. A hose having a wall corrugate6along at least a part of its
length, comprising an inner thin resin layer, a laminated layer
having a metal film held between two resin films and surrounding
the inner resin layer, and an outer thin resin layer surrounding
the laminated layer.
2. A hose as set forth in claim 1, wherein the laminated layer is a
spirally wound or longitudinally lapped layer of a laminated tape
having the metal film bonded to the resin films.
3. A hose as set forth in claim 2, wherein at least the inner resin
layer and the laminated layer, overlapping edge portions of the
laminated tape, or the laminated layer and the outer resin layer
are bonded with an adhesive.
4. A hose as set forth in claim 2, wherein the laminated tape has a
thickness of 200 .mu.m at maximum.
5. A hose as set forth in claim 2, wherein the metal film is of
aluminum and has a thickness of from 7 to less than 200 .mu.m.
6. A process for manufacturing a hose of impermeability comprising
the steps of: extruding an inner thin resin layer about a mandrel;
applying a laminated tape having a metal film held between two
resin films to an outer surface of the inner resin layer to form a
laminated layer; and forming an outer thin resin layer about the
laminated layer by extrusion or electrostatic powder coating to
complete a multi-layered wall, and corrugating the wall along at
least a part of its length, or corrugating a hose structure
composed of the inner resin layer and the laminated layer along at
least a part of its length, and forming an outer thin resin layer
by electrostatic powder coating about the laminated layer to
complete a multi-layered wall.
7. A hose having a wall, corrugated along at least a part of its
length, comprising an inner thin` resin layer, a thin metal layer
surrounding the inner resin layer, and an outer thin resin layer
surrounding the metal layer.
8. A hose as set forth in claim 7, wherein the metal layer is a
spirally wound or longitudinally lapped layer formed by an aluminum
film having a thickness of from 7 to less than 200 .mu.m.
9. A hose as set forth in claim 8, wherein at least the inner resin
layer and the metal layer, overlapping edge portions of the metal
layer, or the metal layer and the outer resin layer are bonded with
an adhesive.
10. A hose as set forth in claim 7, wherein at least one of the
inner and outer resin layers has a thickness of 5 mm at
maximum.
11. A process for manufacturing a hose of impermeability comprising
the steps of: extruding an inner thin resin layer about a mandrel;
applying a metal film onto an outer surface of the inner resin
layer to form a thin metal layer thereabout; forming an outer thin
resin layer on an outer surface of the metal layer by extrusion or
electrostatic powder coating to complete a multilayered wall; and
corrugating the wall along at least a part of its length.
12. A process for manufacturing a hose of impermeability comprising
the steps of: applying a laminated tape composed of metal and resin
films about a mandrel to form a tubular laminated layer; and after
removing the mandrel, coating an inner surface of the laminated
layer with a resin powder electrostatically to form a thin inner
resin layer.
13. A process as set forth in claim 12, further comprising the step
of forming a protective layer surrounding the laminated layer
before or after the coating step.
14. A process as set forth in claim 12, wherein a tubular part for
a hose assembly is connected to the laminated layer before the
coating step, so that the tubular part may also have an inner
surface coated with the resin powder.
15. A process as set forth in claim 12, wherein the laminated tape
is spirally wound or longitudinally lapped about the mandrel.
16. A process as set forth in claim 12, wherein the laminated tape
comprises a metal film and two resin films between which the metal
film is held.
17. A process as set forth in claim 12, wherein the laminated tape
has a thickness of 30 to 200 .mu.m and includes a metal film having
a thickness of 7 to 50 .mu.m.
18. A process as set forth in claim 12, wherein the resin powder is
of a thermoplastic resin and is melted under heat on the inner
surface, the coating and melting being performed at least once.
19. A process as set forth in claim 12, wherein the resin powder is
selected from the group consisting of polyamide, ethylene-vinyl
alcohol copolymer, polyester, modified polyolefin, and fluoro
resins.
20. A process as set forth in claim 19, wherein the modified
polyolefin resin is a silane-crosslinked, acid-modified or
hydroxyl-modified polyethylene resin, and the fluororesin is a
chlorotrifluoroethylene-viny- lidene fluoride copolymer, THV or
PVDF.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a hose of impermeability and a
process for manufacturing the same. More particularly, it relates
to a hose having a very high level of fluid impermeability and
satisfactory flexibility, strength and lightness in weight, and a
process for manufacturing the same.
[0003] 2. Description of the Related Art
[0004] Various kinds of rubber hoses have usually been used as, for
example, fuel hoses in motor vehicles because of their ability to
absorb vibration and their flexibility for assembly. They have,
however, come to be replaced in recent years by hoses formed from
resinous materials having a higher fuel impermeability than
rubbers, since the fuel impermeability of hoses is important for
environmental protection. Hoses formed from fluororesins have,
among others, been preferred because of their particularly high
fuel impermeability.
[0005] The fluororesins are, however, so expensive that it has been
considered that they have to be used in the form of laminates with
other materials that are less expensive. The formation of laminates
requires special techniques, such as tetraetch treatment or plasma
treatment, for the bonding of layers, and equipment therefor. The
control on the permeation of fuel through the walls of hoses is
expected to become still stricter, while it is also necessary to
consider measures against the permeation of other fluids including
carbon dioxide used as a refrigerant and hydrogen used in fuel
cells. The hoses formed solely from organic materials, such as
rubbers and resins including fluororesins, may not be able to
satisfy the future requirement for fluid impermeability.
[0006] It has, therefore, been proposed that hoses have in their
wall a barrier layer of a metal expected to have a very high fluid
impermeability. For example, Japanese Patent Application Laid-Open
No. 127101/1996 discloses a composite hose for hot or waste water
having a wall formed of layers of polybutene, modified polyolefin
and a metal. This hose is, however, designed for use in a building
and does not, therefore, take into account any such factor as
absorption of vibration, flexibility, gasoline resistance, or the
resistance of its resin layers to hydrogen used in fuel cells. The
hose of the type for which this invention is intended is, however,
required to be capable of absorbing vibration, flexible for
assembly, strong and light in weight, as well as having a high
fluid impermeability.
[0007] Japanese Patent Application Laid-Open No. 275981/1995
discloses a resin-coated and corrugated hose made by coating a
straight metal pipe with a resin layer, and corrugating the pipe
and the resin layer by e.g. drawing or hydroforming. It also
discloses a process for manufacturing such a hose. Although it
intends to make a hose flexible and capable of absorbing vibration
by corrugating it, the corrugation of a straight metal pipe and a
resin layer covering it together has the drawback that the residual
stress in the resin layer makes it difficult to retain the shape of
the metal layer unless the metal layer has a relatively large
thickness. The reason is that since up to about 20% of deformation
is laminated tape wound about the resin layer; still in the range
of elastic deformation for the resin, while it is already in the
range of plastic deformation for the metal. In fact, the examples
described therein show a metal layer thickness of 0.2 to 0.7 mm
against a resin layer thickness of 0.5 to 1 mm. A metal layer
having such a large thickness unavoidably adds to the cost of the
hose and its weight and lowers its flexibility and its capability
of absorbing vibration.
SUMMARY OF THE INVENTION
[0008] It is, therefore, considered that a fluid-impermeable
composite metal-resin hose can effectively be made by using as a
barrier layer a laminated layer obtained by protecting a thin metal
film with a resin film, and reinforcing it with a resin layer. The
hose preferably has a corrugated portion which ensures its
flexibility. This invention provides such a composite metal-resin
hose.
[0009] There are two problems to be considered in connection with
the manufacture of such a composite hose. The first problem is
concerned with the adhesion between the laminated layer and the
resin layer lining it, which is important to ensure the fluid
impermeability of the hose. This problem can occur irrespective of
whether the hose may have a corrugated portion, or not. It is
technically difficult to form the laminated layer as a seamless
cylindrical body and there is no alternative but to form a
cylindrical laminated layer by the spiral winding or longitudinal
lapping of a laminated tape formed from a thin metal film and a
resin film. This method, however, has three problems:
[0010] (1) The laminated layer may fail to make a tight seal
because of a clearance formed by a step between every two
overlapping edges of the laminated tape wound about the resin
layer;
[0011] (2) The laminated layer may be low in durability if the
overlapping edges of the laminated tape are displaced from each
other by the bending or deformation of the hose; and
[0012] (3) A step of applying an adhesive to the outer periphery of
the resin layer is required for enhancing its adhesion to the
laminated layer to overcome the above two problems, and lowers the
efficiency of hose manufacture. This invention provides a process
which can overcome these problems.
[0013] The second problem is concerned with a metal layer having an
undesirably large thickness for a corrugated composite metal-resin
hose as pointed out in connection with the disclosure of Japanese
Patent Application Laid-Open No. 275981/1995. The inventors of this
invention have succeeded in forming a metal layer having a
thickness not exceeding, say, 50 .mu.m, while retaining its fluid
impermeability, for a corrugated hose made by laminating the metal
layer and a resin layer. The hose can be made by (a) placing a
corrugated resin layer in a hydroforming die, inserting a metal
pipe therein and hydroforming the whole; or (b) hydroforming a
metal pipe into a corrugated shape and forming a resin layer on the
metal layer by electrostatic powder coating.
[0014] According to a first aspect of this invention, there is
provided a hose having a wall corrugated along at least a part of
its length, and comprising an inner thin resin layer, a laminated
layer formed by disposing a metal film between two resin films and
surrounding the inner thin resin layer, and an outer thin resin
layer surrounding the laminated layer. The hose is of high strength
owing to a multi-layered wall, and also because it has a corrugated
portion which is highly resistant to collapsing. Therefore, it does
not require any resin layer having an undesirably large thickness
to ensure its strength. It is sufficient for each resin layer to
have a thickness not exceeding, say, 5 mm, so that it may be
possible to avoid any undesirable increase in weight of the hose.
The metal film is protected by the resin films when the hose is
corrugated. Even if it may be of very small thickness, the metal
film is not damaged when stretched or bent for the corrugation of
the hose, but forms a barrier layer of high fluid impermeability.
The inner resin layer forms a reliable seal at a hose joint and the
outer resin layer ensures the strength of the hose.
[0015] According to a second aspect of this invention, there is
provided a process for manufacturing a hose of impermeability which
comprises the steps of extruding an inner thin resin layer about a
mandrel to form an innermost layer of the hose; winding a laminated
tape obtained by holding a thin metal film between two resin films
about the inner resin layer to form a laminated layer surrounding
it; and the following step (a) or (b):
[0016] (a) forming an outer thin resin layer about the laminated
layer by extrusion or electrostatic powder coating to complete a
multi-layered wall of the hose, and corrugating the wall along at
least a part of its length; or
[0017] (b) corrugating a wall of the hose including the inner resin
layer and the laminated layer along at least a part of its length,
and then forming an outer thin resin layer about the laminated
layer by electrostatic powder coating to complete a multi-layered
wall of the hose. The force of a corrugating device does not act
directly upon the metal film, but is mitigated by the resin films
between which it is held, or even by the inner and outer resin
layers between which the laminated layer is located. The stretching
or bending of the metal film which occurs during the step of
corrugation occurs only after the corresponding deformation of the
resin films, or layers, and does not, therefore, cause any damage
to the metal film, even if its thickness may be very small. The
metal film forms a barrier layer of very high fluid impermeability
even if it may have a thickness of less than 200 .mu.m to make the
hose flexible, capable of absorbing vibration and light in weight.
The metal film may even have a usually unexpected thickness of less
than 20 .mu.m and ensure the high fluid impermeability of the
hose.
[0018] According to a third aspect of this invention, there is
provided a hose having a wall corrugated along at least a part of
its length and comprising an inner thin resin layer, a thin metal
layer surrounding it and an outer thin resin layer surrounding the
metal layer. The hose is of high strength, since it has a
corrugated portion which is highly resistant to collapsing.
Therefore, it does not require any resin layer having an
undesirably large thickness to ensure its strength. It is
sufficient for each resin layer to have a thickness not exceeding,
say, 5 mm, so that it may be possible to avoid any undesirable
increase in weight of the hose. The metal layer is protected by the
inner and outer resin layers against any damage, and forms a
barrier layer of high fluid impermeability. The inner resin layer
forms a reliable seal at a hose joint and the outer resin layer
ensures the strength of the hose.
[0019] According to a fourth aspect of this invention, there is
provided a process for manufacturing a hose of impermeability which
comprises the steps of extruding an inner thin resin layer about a
mandrel to form the innermost layer of the hose; winding a metal
film about the inner resin layer to form a thin metal layer
thereon; forming an outer thin resin layer about the metal layer by
extrusion or electrostatic powder coating to complete a
multi-layered wall of the hose; and corrugating the wall along at
least a part of its length. The metal layer is held between the
inner and outer resin layers, so that no force of a corrugating
device may act directly upon the metal layer. Therefore, the metal
layer may have even a thickness of less than 200 .mu.m and yet form
a barrier layer of very high fluid impermeability.
[0020] According to a fifth aspect of this invention, there is
provided a process for manufacturing a hose of impermeability which
comprises the steps of winding a laminated tape composed of a metal
film and a resin film about a mandrel to form a tubular laminated
layer; and applying a resin by electrostatic powder coating to the
inner surface of the laminated layer after the removal of the
mandrel therefrom to form a thin resin layer as the innermost layer
of the hose. The laminated layer including the metal film forms a
wall of very high fluid impermeability. The metal film may be small
in thickness, since it is protected by the resin film against
damage or fracture when the hose is bent or deformed. The resin
layer lining the tubular laminated layer enables the metal film to
have a sufficiently small thickness to make the hose flexible for
assembly, strong and light in weight. Other advantages of the
process include the following. Firstly, the resin layer formed by
electrostatic powder coating fills completely the clearance formed
by any step between the overlapping edges of the laminated film
wound to form the tubular laminated layer, so that the laminated
layer may form an improved seal against any fluid. Secondly, such a
resin layer adheres closely to the laminated layer, so that the
hose may form a reliable seal against any fluid, while the
laminated layer is of improved durability. No adhesive is
necessary.
[0021] 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
[0022] FIG. 1 is a cross sectional view of a hose embodying this
invention with a partial enlargement thereof;
[0023] FIGS. 2A to 2F are diagrams illustrating a process embodying
this invention in a simplified pattern;
[0024] FIG. 3 is a view similar to FIG. 1, but showing a different
form of hose embodying this invention; and
[0025] FIGS. 4A to 4D are diagrams illustrating a different process
embodying this invention.
DETAILED DESCRIPTION OF THE INVENTION
[0026] The hose according to the first or third aspect of this
invention has a multi-layered wall corrugated along at least a part
of its length (the remainder being a straight or curved portion
having a smooth surface) and formed by an inner thin resin layer, a
barrier layer surrounding it and an outer thin resin layer
surrounding the barrier layer. The barrier layer is a laminated
layer including a metal film between two resin films, or consists
solely of a metal film.
[0027] The wall may further include a protective layer surrounding
the outer resin layer. A typical example is a solid or spongy
elastomer layer surrounding the hose along a part of its length
(e.g. its corrugated portion), or along its entire length for
making it resistant to chipping by a stone hit by a vehicular
wheel.
[0028] The hose may be used for conveying various kinds of liquids
or gases, including fuel such as gasoline for a motor vehicle,
alcohol or hydrogen for a fuel cell and natural or propane gas for
domestic use, a refrigerant such as Freons or carbon dioxide, and
air for a motor vehicle. The hose according to this invention is
particularly suitable as, for example, a filler hose, since its
wall has a high fluid impermeability, and since electrostatic
powder coating employed for forming its resin layers is suitable
for application to a hose having a large diameter.
[0029] The laminated layer may be of any construction if it is a
tubular layer in which a metal film is tightly held between two
resin films, though it is preferably formed by spiral winding or
longitudinal lapping from a laminated tape made by bonding the
metal film with the resin films. The metal film may be of any
metal, though it is preferably of aluminum, copper, stainless steel
or iron, since these materials are outstanding in one or more of
properties including fluid impermeability, ductility and
deformability. Aluminum is, among others, preferred. The metal film
is not limited in thickness, but preferably has a thickness of from
7 to less than 200 .mu.m to be satisfactory in fluid
impermeability, while ensuring the flexibility of the hose. The
laminated tape may be of any thickness, but its thickness
preferably does not exceed 200 .mu.m to ensure that any clearance
between the overlapping edges of the tape as wound or lapped be
tightly sealed. The resin films may be of any resin, but are
preferably of a thermoplastic resin. A polyamide resin is preferred
because of easy adhesion between one portion of the laminated tape
and another, and between the laminated layer and the inner or outer
resin layer, as well as the ease of corrugation. The resin films
and the resin layers are preferably of the same resin, and more
preferably of a polyamide resin. Each resin film preferably has an
outer surface (i.e. a surface to be adhered) given corona discharge
treatment for improved adhesion.
[0030] The barrier layer consisting solely of a metal film may be
formed in any way, though it is preferably formed by spiral winding
or longitudinal lapping. The metal film may be of any metal and
thickness, though it is preferably a film of aluminum, copper,
stainless steel or iron (particularly aluminum) having a thickness
of from 7 to less than 200 .mu.m for the reasons as stated above in
connection with the laminated layer.
[0031] The inner resin layer formed by extrusion and the outer
resin layer formed by extrusion or electrostatic powder coating may
both be of any resin. Preferred examples are, however, a polyamide
resin, an ethylenevinyl alcohol copolymer (EVOH) resin, a polyester
resin, a modified polyolefin resin and a fluororesin. A polyamide
resin is, among others, preferred. The inner and outer resin layers
may be of the same, or different resins. A silane-crosslinked, or
acid- or hydroxyl-modified polyethylene resin is a preferred
modified polyolefin resin. The hose is required to be highly
resistant to heat if it is used as a fuel, air or coolant hose in
an engine room. If such is the case, the resin layers are
preferably of PET, PBT, PA6 or aromatic nylon because of their high
heat resistance. Other preferred examples are fluororesins
including THV, PVDF, ETFE, PTFE, PFA, FEP and an ethylene
trifluoride-vinylidene fluoride copolymer. The hose is required to
withstand a high temperature and a high humidity if it is used in a
place where it is exposed to hot steam. If such is the case,
preferred examples of resins are a modified polyethylene resin and
a polyamide resin having a low water-absorbing capacity, such as
PA11, PA12 or aromatic polyamide. The resin layers may be of very
small thickness for the reasons stated before. For example, the
inner or outer resin layer, or both may have a thickness not
exceeding 5 mm. It is, however, not desirable for the inner resin
layer to have a thickness of less than 40 .mu.m to ensure the
reliability of a seal at a hose joint, nor is it desirable for the
outer resin layer to have a thickness of less than 50 .mu.m to
ensure the strength of the hose.
[0032] Reference is made to FIG. 1 showing a hose 1 having a
multi-layered wall as described above. Its wall is corrugated along
at least a part of its length, though not shown as such, and the
remainder thereof, if any, is a straight or curved portion having a
smooth surface. The wall has an inner thin resin layer 2 and a
barrier layer formed around it by double longitudinal lapping with
a barrier sheet 3. The barrier sheet 3 is a laminated tape composed
of metal and resin films, or consists solely of a metal film. The
barrier sheet 3 is surrounded by an outer thin resin layer 4. The
outer resin layer 4 may be surrounded by a protective layer
consisting of a layer of an appropriate material, such as rubber, a
resin or reinforcing fibers, or a combination of materials. The
inner resin layer 2, barrier sheet 3, and outer resin layer 4 are
bonded to one another with an adhesive, and the circumferentially
extending overlapping portions of the barrier sheet 3 are likewise
bonded together.
[0033] The processes according to the second and fourth aspects of
this invention are basically the same except the construction of a
barrier layer. An inner thin resin layer is formed by extrusion
about a mandrel. A barrier layer is formed about the inner resin
layer by applying either a laminated tape including a metal film
held between two resin films, or simply a metal film. Then, an
outer thin resin layer is formed about the barrier layer by
extrusion or electrostatic powder coating, whereby a hose is
obtained. The hose is at least partly corrugated. According to the
second aspect of this invention, it is alternatively possible to
corrugate at least partly a tubular body as formed by applying a
laminated tape and thereafter form an outer resin layer by
electrostatic powder coating.
[0034] A typical process for electrostatic powder coating includes
the steps of coating a surface electrostatically with a
thermoplastic resin powder and melting the powder under heat,
though any other process can be employed if it can form a uniform
layer from a resin powder. A multi-layered resin layer may be
formed by repeating electrostatic powder coating.
[0035] Any method can be used for applying a laminated tape, or
metal film to form a barrier layer if it can form a tight tubular
layer. Spiral winding or longitudinal lapping is, however,
preferred for a quick job and a tight seal. Spiral winding means
winding a tape spirally about a tubular body, and longitudinal
lapping means enclosing a tubular body in a tape, or sheet
extending along its longitudinal axis.
[0036] The laminated tape or metal film is preferably so wound as
to have overlapping edge portions having an adequate width to
ensure a reliable fluid seal. An improved seal can be formed if two
or more overlapping layers are formed by spiral winding or
longitudinal lapping. This is possible by employing two or more
tapes, or films, or a tape, or film having a large width and
thereby making it possible to form overlapping edge portions having
a large width.
[0037] The wall layers, as well as the overlapping portions of the
barrier layer, are preferably bonded together to ensure an improved
seal. In this connection, it is effective to coat the outer surface
of the inner resin layer with an adhesive before winding the tape
or film thereon, as well as coating the tape or film with an
adhesive before forming the outer resin layer. The overlapping
portions of the barrier layer can be bonded together with an
adhesive. If the barrier layer is formed by a laminated tape, its
resin films and the inner and outer resin layers can be fused
together under heat after the hose is made.
[0038] The hose may be corrugated by any method, for example, using
rolls. It is, however, preferable to corrugate the pipe by
hydroforming, i.e. applying a liquid pressure to the interior of
the hose in a die. The hose to be corrugated is preferably heated
to a temperature of, say, 80.degree. C. so that the resin layers
(and the resin films in the barrier layer) may be softened to some
extent.
[0039] Attention is now directed to FIGS. 2A to 2F illustrating the
process according to the second or fourth aspect of this invention.
An inner thin resin layer 2 is formed by extrusion about a mandrel
5 in an extruder not shown, as shown in FIG. 2A. A barrier layer is
formed about the inner resin layer 2 by lapping it with a barrier
sheet 3 as shown in FIG. 2B, or by winding a tape 3 spirally as
shown in FIG. 2C. Then, an outer thin resin layer 4 is formed about
the barrier layer 3 by extrusion or electrostatic powder coating,
whereby a hose is made. If the latter method is employed, a resin
powder is applied onto the barrier layer by an electrostatic
coating gun 6, and melted under heat to form the outer resin layer
4, as shown in FIG. 2D. After the mandrel 5 is removed from it, the
hose 7 is placed in a hydroforming die 8, as shown in FIG. 2E or
2F, and a liquid pressure is applied into the hose 7 to corrugate
it along at least a part of its length. The die 8 shown in FIG. 2F
is a split die consisting of an upper and a lower portion each
having five separate elements which are movable to and away from
one another as shown by broken arrows. The hose 7 to be corrugated
may be heated to some extent, so that the resin may be softened.
The process may further include adequate steps of bonding the
layers, or the overlapping portions of the barrier layer 3 with an
adhesive, or under heat, as described before.
[0040] The process according to the fifth aspect of this invention
includes the steps of winding a laminated tape composed of metal
and resin films about a mandrel to form a tubular laminated layer,
and coating the inner surface of the tubular laminated layer with a
resin powder electrostatically after the removal of the mandrel
therefrom to form a thin resin layer as the innermost layer of a
multi-layered wall for a hose. It may further include other
adequate steps, such as a preferably covering step to be described
later. A tubular part for a hose assembly may be connected to the
tubular laminated layer before the resin layer is formed.
[0041] Referring to the step of forming as tubular laminated layer,
the laminated tape is preferably composed of a metal film and two
resin films bonded together adhesively or under heat to hold the
meal film therebetween, though any other type of tape can be used
if it is a laminate of metal and resin films. The metal film may be
of any metal, though aluminum, copper, titanium or stainless steel
is preferred because of their fluid impermeability, ductility or
deformability. Aluminum is, among others, preferred. The meal film
is not particularly limited in thickness, though a thickness of,
say, 7 to 50 .mu.m may be preferred for the flexibility of the hose
and the fluid impermeability of the metal film. The laminated tape
as a whole is not limited particularly in thickness, either, though
a thickness of, say, 30 to 200 .mu.m may be preferred to ensure a
reliable seal between the overlapping portions, as discussed
before. The resin films may be of any resin layer which is formed
on the inner surface fo the laminated layer, as well as a
protective layer covering it, if any. The resin films, the inner
resin layer and the protective layer are preferably of the same
resin. Each resin film preferably has its outer surface treated for
improved adhesion, as by corona discharge treatment. The laminated
layer may be formed by any method if it is a tight tubular layer.
Spiral winding or longitudinal lapping is, however, preferred for a
quick job and a tight seal. The layer is preferably so formed as to
have overlapping edge portions having an adequate width to ensure
an effective fluid seal, and those overlapping portions are
preferably bonded to each other to ensure that the tubular
laminated layer remain in good shape even after the removal of the
mandrel therefrom. The mandrel may be any appropriate round bar, or
tube having an outside diameter corresponding to the inside
diameter of the hose to be made. The mandrel is preferably used
when an outer protective layer is formed by extrusion, too.
[0042] The resin layer forming the innermost wall layer of the hose
is preferably formed after any tubular part for a hose assembly is
connected to the tubular laminated layer, so that the resin layer
may cover the inner surface of any such part, too. It is formed by
an electrostatic powder coating process which typically includes
the steps of coating the surface electrostatically with a
thermoplastic resin powder and melting the powder under heat,
though any other process can be employed if it can form a uniform
layer on the inner surface of the tubular laminated layer from a
resin powder. A multi-layered resin layer can be formed by
repeating such a process. The resin powder is preferably of, for
example, a polyamide, ethylene-vinyl alcohol copolymer (EVOH),
polyester, modified polyolefin, or fluoro resin. If the resin films
in the barrier layer are of a polyamide resin, the powder is
preferably of the same resin, too. A silane-crosslinked, or acid-
or hydroxyl-modified polyethylene resin is a preferred modified
polyolefin resin. If the hose is required to be highly resistant to
heat as when it is used as a fuel, air or coolant hose in an engine
room, the resin layer is preferably formed from a powder of, for
example, PA6, PET, PBT a chlorotrifluoroethylene-vinylidene
fluoride copolymer THV or PVDF because of their high heat
resistance. If the hose is intended for use in a place where it
will be exposed to hot steam, the resin layer is preferably formed
from, for example, a modified polyethylene resin or a polyamide
resin having a low water-absorbing capacity, such as PA11, PA12 or
aromatic polyamide, because of their resistance to high temperature
and humidity. The resin layer cannot be of any definite thickness,
but its thickness may depend on the resin forming it and the
purpose for which the hose will be used. For example, however, it
may have a thickness of about 20 to 200 .mu.m if it is of a
polyamide resin, about 40 to 300 .mu.m if it is of a modified
polyolefin resin, or about 20 to 100 .mu.m if it is of a
fluororesin.
[0043] The preferable covering step is the step of forming a
protective layer of e.g. a resin or rubber on the outer surface of
the tubular laminated layer. It may be carried out before the resin
layer is formed on the inner surface of the tubular laminated
layer, or thereafter. It is, however, efficient to form the
protective layer by extrusion before removing the mandrel for
forming the inner resin layer. The protective layer may be of any
appropriate material and construction. It may, for example, a
rubber or resin layer, or a layer composed of two rubber layers
between which a layer of spirally wound or braided reinforcing
yarns is held. It may be formed by, for example, an appropriate
combination of extrusion or injection molding and yarn braiding. If
a rubber layer is formed by extrusion or injection molding, its
curing is usually required. If the protective layer is of rubber,
it is preferably formed from, for example, hydrin rubber, NBR-PVC,
a composite of halogenated butyl rubber and EPDM
(ethylene-propylene-diene rubber), a composite of fluororubber and
NBR-PVC, or EPDM to ensure adhesion to the tubular laminated layer,
particularly if the resin films in the laminated layer are of a
polyamide resin. A protective layer of a resin may be formed from a
thermoplastic resin by extrusion. It is preferably formed from, for
example, a polyamide resin such as PA6, PA11 or PA12, a modified
polyethylene resin (PE), a composite of PE and modified PE, a
modified polypropylene resin (PP), a composite of PP and modified
PP, or a composite of modified PP and SANTOPRENE (a thermoplastic
elastomer formed from PP and EPDM), particularly if the resin films
in the laminated layer are of a polyamide resin. If the hose is
required to be resistant to heat or hot steam, the layer is
preferably of a resin having a high resistance to heat or moisture
as mentioned before.
[0044] Reference is now made to FIG. 3 showing a hose made by the
process according to the fifth aspect of this invention. The hose
11 has a multi-layered wall including a tubular laminated layer 13
formed by a laminated tape 12 composed of metal and resin films,
and a thin resin layer 14 formed by electrostatic powder coating on
the inner surface of the laminated layer 13. The laminated layer 13
is surrounded by a protective layer 15 formed from an appropriate
material, such as rubber, a resin, reinforcing yarns, or a
combination thereof. The laminated layer 13 is formed by
longitudinal lapping, and has a pair of overlapping edge portions
16 bonded to each other with an adhesive.
[0045] FIGS. 4A to 4D illustrates a mode of carrying out the
process according to the fifth aspect of this invention. A
laminated tape 12 is applied about a mandrel 17 in an extruder not
shown to form a tubular laminated layer 13 by spiral winding as
shown in FIG. 4A, or by longitudinal lapping as shown in FIG. 4B. A
protective layer 15 is formed by extrusion to cover the laminated
layer 13 on the mandrel 17, as shown in FIG. 4C. If the protective
layer 15 contains rubber, it is cured, and if it includes
reinforcing yarns, they are braided. Then, the mandrel 17 is pulled
out from the laminated layer 13, and a resin powder is applied onto
the inner surface of the laminated layer 13 by an electrostatic
coating gun 18, as shown in FIG. 4D. A tubular part for a hose
assembly not shown may be connected to the laminated layer 13 prior
to electrostatic powder coating, so that the inner surfaces of the
laminated layer 13 and the hose assembly may be coated together
with the resin powder. Then, the resin powder is melted under heat
to form a resin layer as shown at 14 in FIG. 3.
EXAMPLES
[0046] The invention will now be described in further detail by
specific examples. Description will first be made of two sets of
examples covering the first to fourth aspects of this invention.
[Hoses Having an Outer Resin Layer Formed by Electrostatic Powder
Coating]
[0047] Hoses having smooth surfaces were made as described at
Examples 1-1 to 1-6 below. Then, they were corrugated to make
corrugated hoses of impermeability as described at Examples 1-7 to
1-11. The hose according to Example 1-6 was not corrugated because
of the cracking of its aluminum film.
Example 1-1
[0048] A tubular layer of nylon 6 having a wall thickness of 200
.mu.m was formed by extrusion about a resin mandrel having a
diameter of 25 mm. A polyurethane-based adhesive (Hibon.RTM. of
Hitachi Chemical Polymer Co., Ltd.) Was applied onto the outer
surface of the nylon layer. The nylon layer was longitudinally
lapped with a doubly wound laminated tape composed of an aluminum
film having a thickness of 20 .mu.m held between two films of nylon
6 each having a thickness of 25 .mu.m. the laminated tape had a
pair of overlapping edge portions bonded to each other with the
same adhesive to form a tubular laminated layer. The laminated
layer was electrostatically coated with a powder of PA11
(Rilsan-find-powder of Atofina Chemicals, Inc.), and the powder was
heated to form a thin resin layer having a thickness of 70 .mu.m,
whereby a hose was made.
Example 1-2
[0049] A hose was made by employing an aluminum film having a
thickness of 9 .mu.m and otherwise repeating Example 1-1.
Example 1-3
[0050] A hose was made by employing an aluminum film having a
thickness of 6 .mu.m and otherwise repeating Example 1-1.
Example 1-4
[0051] A hose was made by employing an aluminum film having a
thickness of 20 .mu.m without any resin film holding it, and
otherwise repeating Example 1-1.
Example 1-5
[0052] A hose was made by employing an aluminum film having a
thickness of 9 .mu.m and otherwise repeating Example 1-4.
Example 1-6
[0053] A hose was made by employing an aluminum film having a
thickness of 6 .mu.m and otherwise repeating Example 1-4.
Example 1-7
[0054] A hose having a length of 300 mm was cut from the hose made
in Example 1-1, and was corrugated to make a corrugated hose of
impermeability having a ridge height of 2 mm and a ridge pitch of 4
mm by an ordinary hydroforming process in which a maximum liquid
pressure of 200 kgf/cm.sup.2 was employed, while the hydroforming
die and liquid were heated to a temperature of 150.degree. C.
Example 1-8
[0055] A corrugated hose was made by employing the hose made in
Example 1-2 and otherwise repeating Example 1-7.
Example 1-9
[0056] A corrugated hose was made by employing the hose made in
Example 1-3 and otherwise repeating Example 1-7.
Example 1-10
[0057] A corrugated hose was made by employing the hose made in
Example 1-4 and otherwise repeating Example 1-7.
Example 1-11
[0058] A corrugated hose was made by employing the hose made in
Example 1-5 and otherwise repeating Example 1-7.
[0059] [Hoses Having an Outer Resin Layer Formed by Extrusion]
[0060] Hoses having smooth surfaces were made as described at
Examples 2-1 to 2-6 below. Then, they were corrugated to make
corrugated hoses of impermeability as described at Examples 2-7 to
2-11. The hose according to Example 2-6 was not corrugated because
of the cracking of its aluminum film.
Example 2-1
[0061] A tubular layer of nylon 6 having a wall thickness of 200
.mu.m was formed by extrusion about a resin mandrel having a
diameter of 25 mm. A polyurethane-based adhesive (Hibon.RTM. of
Hitachi Chemical Polymer Co., Ltd.) was applied onto the outer
surface of the nylon layer. The nylon layer was longitudinally
lapped with a doubly wound laminated tape composed of an aluminum
film having a thickness of 20 .mu.m held between two films of nylon
6 each having a thickness of 25 .mu.m. The laminated tape had a
pair of overlapping edge portions bonded to each other with the
same adhesive to form a tubular laminated layer. Then, a layer of
nylon 6 having a thickness of 200 .mu.m was formed by extrusion
about the tubular laminated layer, and fused thereto by the heat of
extrusion.
Example 2-2
[0062] A hose was made by employing an aluminum film having a
thickness of 9 .mu..mu.m and otherwise repeating Example 2-1.
Example 2-3
[0063] A hose was made by employing an aluminum film having a
thickness of 6 .mu.m and otherwise repeating Example 2-1.
Example 2-4
[0064] A hose was made by employing an aluminum film having a
thickness of 20 .mu.m without any resin fil holding it, and
otherwise repeating Example 2-1.
Example 2-5
[0065] A hose was made by employing an aluminum film having a
thickness of 9 .mu.m and otherwise repeating Example 2-4.
Example 2-6
[0066] A hose was made by employing an aluminum film having a
thickness of 6 .mu.m and otherwise repeating Example 2-4.
Example 2-7
[0067] A hose having a length of 300 mm was cut from the hose made
in Example 2-1, and was corrugated to make a corrugated hose of
impermeability having a ridge height of 2 mm and a ridge pitch of 4
mm by an ordinary hydroforming process in which a maximum liquid
pressure of 200 kgf/cm.sup.2 was employed, while the hydroforming
die and liquid were heated to a temperature of 150.degree. C.
Example 2-8
[0068] A corrugated hose was made by employing the hose made in
Example 2-2 and otherwise repeating Example 2-7.
Examples 2-9
[0069] A corrugated hose was made by employing the hose made in
Example 2-3 and otherwise repeating Example 2-7.
Examples 2-10
[0070] A corrugated hose was made by employing the hose made in
Example 2-4 and otherwise repeating Example 2-7.
Examples 2-11
[0071] A corrugated hose was made by employing the hose made in
Example 2-5 and otherwise repeating Example 2-7.
[0072] [Evaluation of Hoses for Impermeability]
[0073] A fluid impermeability test was conducted on each of the
hoses and corrugated hoses which had been made as described above,
except those of Examples 1-6 and 2-6 which had cracked in their
aluminum films. A steel pipe having an outside diameter of 25.5 mm
and a wall thickness of 0.5 mm and capable of being connected with
another was press fitted in each end of the hose to be tested, and
secured thereto with an adhesive and a worm gear clamp. The hose
was plugged at one end, and supplied with gasoline through the
other end. After it was held at a pressure of 0.5 MPa for 24 hours,
the hose was visually inspected for any leakage of gasoline at its
joints with the steel pipes. Even if no leakage was found, the hose
was organoleptically checked for any smell of gasoline. No leakage
was found with any hose, but a smell of gasoline was perceived from
the products of Examples 1-3, 1-9, 2-3 and 2-9.
[0074] Description will now be made of a set of examples covering
the fifth aspect of the invention.
Example 1
[0075] A laminated tape was prepared by holding an aluminum film
having a thickness of 9 .mu.m between two films of nylon 6 each
having a thickness of 25 .mu.m. It was wound by longitudinal
lapping about a resin mandrel having a diameter of 25 mm to form a
tubular laminated layer having a pair of appropriately wide
overlapping edge portions. The overlapping edge portions were
bonded to each other with a polyurethane-based adhesive (Hibon.RTM.
of Hitachi Chemical Polymer Co., Ltd.). Then, a hydrin rubber layer
having a thickness of 2 mm was formed about the laminated layer by
extrusion, and cured to make a hose. After the mandrel had been
removed, the hose had its inner surface coated electrostatically
with a powder obtained by freezing and crushing commercially
available EVOH pellets (EVAL.RTM. of Kuraray Co., Ltd.) and was
heated, so that the powder might be melted to form a thin resin
layer, whereby a hose of impermeability was made.
Example 2
[0076] Example 1 was repeated for forming a laminated layer and
bonding its overlapping edge portions together. A layer of
brominated butyl rubber having a thickness of 0.3 mm and a layer of
EPDM having a thickness of 1.7 mm were formed by extrusion about
the laminated layer. Example 1 was repeated for curing, mandrel
removal, electrostatic EVOH powder coating and heating to form a
thin resin layer, whereby a hose was made. The hose had its inner
surface coated electrostatically with a powder of PA1I
(Rilsan-fine-powder of Atofina Chemicals, Inc.) and the powder was
heated to form another thin resin layer, whereby a hose of
impermeability was made. The hose had two thin resin layers in its
wall.
Example 3
[0077] A laminated film was prepared by holding an aluminum film
having a thickness of 9 pm between an inner film of nylon 6 and an
outer film of nylon 11 each having a thickness of 25 pm. It was
spirally wound about a resin mandrel having a diameter of 25 mm for
forming a laminated layer and its overlapping edge portions were
bonded together. A layer of PA11 having a thickness of 0.9 mm and
containing 7% by weight of a plasticizer was formed by extrusion
about the laminated layer. Example 2 was thereafter repeated for
forming two film resin layers, whereby a hose of impermeability was
made.
Example 4
[0078] A hose was made by forming a layer of PA11 by electrostatic
powder coating and heating, and otherwise repeating Example 3.
Example 5
[0079] A laminated film according to Example 3 was used for forming
a laminated layer by longitudinal lapping and bonding its
overlapping edge portions together as in Example 1. A hydrin rubber
layer was formed about it by extrusion, and cured, whereby a hose
was made. The hose was cut into a length of 200 .mu.m. A degreased
steel pipe having an outside diameter of 25.5 mm and a length of
10.2 mm and capable of being connected to another was coated with a
primer (Rilprim.RTM. of Atofina Chemicals, Itc.) on the inner
surface of its end portion having a length of 20 mm, and was press
fitted in each open end of the hose. After the steel primer, the
hose and the steel pipe had their inner surfaces coated
electrostatically with a powder of PA11 (Rilsan-fine-powder of
Atofina Chemicals, Itc.) And the powder was heated to form a thin
resin layer, whereby a hose of impermeability was made in the form
of a hose assembly.
Comparative Example 1
[0080] A hose was made by forming only a single thin resin layer
and otherwise repeating Example 2.
Reference Example 1
[0081] A laminated tape was prepared by holding an aluminum film
having a thickness of 20 .mu.m between two films of nylon 6 each
having a thickness of 50 .mu.m. Example 1 was repeated for
longitudinal lapping and edge bonding. Example 2 was repeated for
forming two protective layers and curing them. After the removal of
the mandrel, Example 1 was repeated for forming a thin rein layer
by electrostatic powder coating, whereby a hose of low permeability
was made.
[0082] [Evaluation of Hoses]
[0083] (Sealing)
[0084] Each hose, except the product of Example 5, was cut into a
length of 200 mm and a steel as in Example 5 was press fitted in
each end of the hose. Each hose, including the product of Example
5, was secured by a worm gear clamp. The hose was plugged at one
end, and supplied with water through the other end. After 30
seconds at a pressure of 0.4 Mpa, the hose was visually inspected
for any blotting with water (wetting), or leakage (dropping of
water) at its joints with the steel pipes. No blotting or leakage
was found on any of the products of Examples 1 to 5, though leakage
was found on the product of Comparative Example 1, and blotting on
that of Reference Example 1.
[0085] (Inner Surfaces of Hoses Filled with Fuel)
[0086] The procedures as described above for evaluation on sealing
were followed for connecting steel pipes to each hose. The hose was
filled with Fuel C containing 50% by volume of toluene and 50% by
volume of isooctane and after 168 hours of aging at 40.degree. C.,
the inner surface of the hose was visually inspected. Nothing wrong
was found on any hose, except the product of Comparative Example 1
in which a clearance was found between the overlapping portions of
the laminated layer.
[0087] 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.
* * * * *