U.S. patent application number 11/059333 was filed with the patent office on 2005-09-01 for fuel container.
This patent application is currently assigned to NISSAN MOTOR CO., LTD.. Invention is credited to Himeki, Hiroaki, Kumagai, Hiroshi.
Application Number | 20050191452 11/059333 |
Document ID | / |
Family ID | 34747541 |
Filed Date | 2005-09-01 |
United States Patent
Application |
20050191452 |
Kind Code |
A1 |
Kumagai, Hiroshi ; et
al. |
September 1, 2005 |
Fuel container
Abstract
A fuel container having a multi-layer structure, to be used as a
fuel tank of an automotive vehicle. The fuel container includes at
least one fuel permeation preventing layer whose main component is
a first barrier-functional resin, and base material layers whose
main component is a thermoplastic resin is secured to the fuel
permeation preventing layer. In the above-mentioned base material
layers, at least one base material layer is a barrier-functional
base material layer which contains a second barrier-functional
resin homogeneous with the first barrier-functional resin.
Inventors: |
Kumagai, Hiroshi; (Kanagawa,
JP) ; Himeki, Hiroaki; (Kanagawa, JP) |
Correspondence
Address: |
FOLEY AND LARDNER
SUITE 500
3000 K STREET NW
WASHINGTON
DC
20007
US
|
Assignee: |
NISSAN MOTOR CO., LTD.
|
Family ID: |
34747541 |
Appl. No.: |
11/059333 |
Filed: |
February 17, 2005 |
Current U.S.
Class: |
428/35.7 |
Current CPC
Class: |
B32B 2331/04 20130101;
B29C 49/22 20130101; B32B 1/02 20130101; B32B 2309/105 20130101;
Y10T 428/1352 20150115; B29C 49/04 20130101; B29K 2995/0067
20130101; B32B 27/32 20130101; B32B 27/08 20130101; B32B 27/18
20130101; B32B 27/306 20130101; B29C 49/0005 20130101; B29L
2031/7172 20130101; B32B 2307/7265 20130101; B32B 2439/00 20130101;
B60K 2015/03046 20130101; B60K 15/03177 20130101 |
Class at
Publication: |
428/035.7 |
International
Class: |
B65D 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 27, 2004 |
JP |
2004-053531 |
Claims
What is claimed is:
1. A fuel container having a multi-layer structure, comprising: at
least one fuel permeation preventing layer whose main component is
a first barrier-functional resin; and at least one base material
layer whose main component is a thermoplastic resin, the at least
one base material layer being secured to the fuel permeation
preventing layer, at least one layer of the at least one base
material layer containing a second barrier-functional resin
homogeneous with the first barrier-functional resin to form a
barrier-functional base material layer, the second
barrier-functional resin being lamina-like and dispersed in the
thermoplastic resin.
2. A fuel container having a multi-layer structure, comprising: at
least one fuel permeation preventing layer whose main component is
a first barrier-functional resin; at least one base material layer
whose main component is a thermoplastic resin, the at least one
base material layer being secured to the fuel permeation preventing
layer; and at least one barrier-functional base material layer
whose main component is a thermoplastic resin, the at least one
barrier-functional base material layer being secured to the fuel
permeation preventing layer, the barrier-functional base material
layer containing a second barrier-functional resin which is
homogeneous with the first barrier-functional resin, the second
barrier-functional resin being lamina-like and dispersed in the
thermoplastic resin of the at least one barrier-functional base
material layer.
3. A fuel container as claimed in claim 2, wherein the
barrier-functional base material layer is disposed outside of the
fuel permeation preventing layer.
4. A fuel container as claimed in Clam 2, wherein the
barrier-functional base material layer is disposed inside of the
fuel permeation preventing layer.
5. A fuel container as claimed in claim 2, wherein the base
material layer serves as an innermost layer of the fuel
container.
6. A fuel container as claimed in claim 2, wherein the base
material layer serves as an outermost layer of the fuel
container.
7. A fuel container as claimed in claim 2, wherein the
thermoplastic resin as the main component of the base material
layer is olefin resin, wherein each of the first and second
barrier-functional resins is at least one of vinyl alcohol resin
and vinyl alcohol-based copolymer resin.
8. A fuel container as claimed in claim 7, wherein the olefin resin
as the main component of the base material layer is polyethylene,
wherein each of the first and second barrier-functional resins is
at least one selected from the group consisting of ethylene-vinyl
alcohol copolymer resin, polyvinyl alcohol resin and a mixture of
ethylene-vinyl alcohol copolymer and polyvinyl alcohol resin.
9. A fuel container as claimed in claim 2, wherein the lamina-like
second barrier-functional resin has a maximum length of not less
than 5 mm.
10. A fuel container as claimed in claim 2, wherein the lamina-like
second barrier-functional resin has a maximum thickness of not less
than 10 .mu.m.
11. A fuel container as claimed in claim 2, wherein the
barrier-functional base material layer contains the second
barrier-functional resin in an amount ranging from 2 to 12 mass
%.
12. A fuel container as claimed in claim 2, wherein the fuel
container is produced by blow-molding a parison of a multi-layer
structure.
13. A method of producing a fuel container having a multi-layer
structure, comprising: extruding a parison having a multi-layer
structure and including at least one fuel permeation preventing
layer whose main component is a first barrier-functional resin, and
at least one base material layer whose main component is a
thermoplastic resin, the at least one base material layer being
secured to the fuel permeation preventing layer, at least one layer
of the at least one base material containing a second
barrier-functional resin homogeneous with the first
barrier-functional resin to form a barrier-functional base material
layer, the second barrier-functional resin being lamina-like and
dispersed in the thermoplastic resin; putting the parison in a blow
mold so as to form a pinch-off area; and expanding the parison in
the blow mold with pressured air.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relate to improvements in a fuel container
used mainly as a fuel tank of an automotive vehicle, and more
particularly to the fuel container having a multi-layer structure
and formed of plastic or resin.
[0002] A fuel tank of an automotive vehicle is conventionally
formed of metal; however, the material of the fuel tank is being
shifted to plastic from the viewpoints of being light in weight,
high in freedom in design, excellent in corrosion resistance and
low in cost. As one of environmental protection measures,
regulations for fuel evaporation from automotive vehicles are
becoming strict in many countries. Accordingly, it is general that
a fuel tank has a multi-layer structure which includes a barrier
layer for preventing permeation of fuel.
[0003] As the fuel tank of the above type, there has been proposed
one including a barrier layer formed of ethylene-vinyl alcohol
copolymer (EVOH) resin excellent in permeation preventing
characteristics for a mixture fuel containing alcohol, and two base
material layers which are disposed on the opposite sides of the
barrier layer and adhered through adhesive layers to the barrier
layer. Additionally, there has been also proposed a fuel tank of
the type wherein two polyolefin layers are disposed on the opposite
surfaces of a barrier layer through adhesive layers each of which
contains therein a discontinuous lamina layer, as disclosed in
Japanese Patent Provisional Publication No. 6-24430.
SUMMARY OF THE INVENTION
[0004] The above fuel tanks are produced by blow-molding a parison
having a multi-layer structure. During the blow-molding, a part of
the parison having the multi-layer structure is pinched between two
halves of a mold to form a pinch-off area. In this pinch-off area,
the barrier layer located at the intermediate position in the
multi-layer structure becomes into a state of being cut, so that a
preventing performance to fuel permeation cannot be obtained at the
pinch-off area. Additionally, the thickness of each adhesive layer
containing therein the laminar layer is so small as about 50 to 300
.mu.m, and therefore the adhesive layer is also brought into a
condition of being cut in the pinch-off area like the barrier layer
thereby making it difficult to obtain the preventing performance to
fuel permeation at the pinch-off area.
[0005] In order to obtain the fuel permeation preventing
performance at the pinch-off area, there are proposed a method of
covering the upper surface (outer surface) of the pinch-off area
with a cover having a gas barrier function, a method of coating the
upper surface of the pinch-off area with a resin having a gas
barrier function and a method for disposing an alloy resin of
polyethylene and nylon at an innermost layer forming an inner
surface of the fuel tank.
[0006] However, with the method of using the cover or the coated
resin, there is the fear of degrading the freedom in design as an
advantage of the plastic-made fuel tank. With the method of
disposing the alloy resin at the innermost layer, when surplus or
excess materials produced in a production process of the fuel tank
is kneaded for recycling within the production process, hydroxyl
groups of EVOH resin and amide group of nylon react with each other
to occur gelation, and EVOH resin deteriorates under kneading at a
high temperature condition required for nylon having a high melting
point, thereby providing the fear of lowering the physical
properties of recycled materials. Additionally, all the methods
mentioned above raise production cost of the fuel tank.
[0007] It is, therefore, an object of the present invention to
provide an improved fuel container which can effectively overcome
drawbacks encountered in conventional fuel container or tanks
having a multi-layer structure.
[0008] Another object of the present invention is to provide an
improved fuel container which has a sufficient fuel permeation
preventing performance to meet strict regulations for fuel emission
control.
[0009] A further object of the present invention is to provide an
improved fuel container which can have a sufficient fuel permeation
interrupting effect even at a pinch-off area formed during a blow
molding without degrading any advantages of a plastic-made fuel
container.
[0010] An aspect of the present invention resides in a fuel
container having a multi-layer structure, comprising at least one
fuel permeation preventing layer whose main component is a first
barrier-functional resin. Additionally, at least one base material
layer whose main component is a thermoplastic resin, secured to the
fuel permeation preventing layer. At least one layer of the at
least one base material layer contains a second barrier-functional
resin homogeneous with the first barrier-functional resin to form a
barrier-functional base material layer. The second
barrier-functional resin is lamina-like and dispersed in the
thermoplastic resin.
[0011] Another aspect of the present invention resides in a fuel
container having a multi-layer structure, comprising at least one
fuel permeation preventing layer whose main component is a first
barrier-functional resin. At least one base material layer whose
main component is a thermoplastic resin is secured to the fuel
permeation preventing layer. Additionally, at least one
barrier-functional base material layer whose main component is a
thermoplastic resin is secured to the fuel permeation preventing
layer. The barrier-functional base material layer contains a second
barrier-functional resin which is homogeneous with the first
barrier-functional resin. The second barrier-functional resin is
lamina-like and dispersed in the thermoplastic resin of the at
least one barrier-functional base material layer.
[0012] A further aspect of the present invention resides in a
method of producing a fuel container having a multi-layer
structure. The method comprises (a) extruding a parison having a
multi-layer structure and including at least one fuel permeation
preventing layer whose main component is a first barrier-functional
resin, and at least one base material layer whose main component is
a thermoplastic resin, the at least one base material layer being
secured to the fuel permeation preventing layer, at least one layer
of the at least one base material containing a second
barrier-functional resin homogeneous with the first
barrier-functional resin to form a barrier-functional base material
layer, the second barrier-functional resin being lamina-like and
dispersed in the thermoplastic resin; (b) putting the parison in a
blow mold so as to form a pinch-off area; and (c) expanding the
parison in the blow mold with pressured air.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] In Figures, like reference numerals designate like parts and
elements throughout all figures, in which:
[0014] FIG. 1 is a fragmentary sectional view of a first embodiment
of a fuel container according to the present invention, showing a
five-layer structure;
[0015] FIG. 2 is a fragmentary sectional view of a second
embodiment of a fuel container according to the present invention,
showing a six-layer structure;
[0016] FIG. 3 is a fragmentary sectional view of a third embodiment
of the fuel container according to the present invention, showing a
five-layer structure;
[0017] FIG. 4 is a fragmentary sectional view of a fourth
embodiment of the fuel container according to the present
invention, showing a six-layer structure;
[0018] FIG. 5 is a fragmentary sectional view, illustrating a
pinch-off area formed during a blow molding of the fuel container
shown in FIG. 1; and
[0019] FIG. 6 is a fragmentary sectional view, illustrating a
portion of the fuel container of FIG. 3 which portion is formed
with an opening for installation of a part.
DETAILED DESCRIPTION OF THE INVENTION
[0020] According to the present invention, a fuel container having
a multi-layer structure, comprising at least one fuel permeation
preventing layer whose main component is a first barrier-functional
resin. Additionally, at least one base material layer whose main
component is a thermoplastic resin, secured to the fuel permeation
preventing layer. At least one layer of the at least one base
material layer contains a second barrier-functional resin
homogeneous with the first barrier-functional resin to form a
barrier-functional base material layer. The second
barrier-functional resin is lamina-like and dispersed in the
thermoplastic resin.
[0021] Referring now to FIG. 1, a fragmentary section of a first
embodiment of a fuel container according to the present invention
is illustrated. In FIG. 1, a right side corresponds to an outer
side of the fuel container. The fuel container comprises fuel
permeation preventing layer 11 whose main component is a first
barrier-functional resin. Adhesive layers 12, 14 are disposed on
the opposite sides of fuel permeation preventing layer 11 and
adhered to fuel permeation preventing layer 11. Adhesive layer 14
is disposed outside of fuel permeation preventing layer 11. Base
material layer 18 is disposed outside of adhesive layer 14 and
adhered to the adhesive layer 14. The main component of base
material layer 18 is thermoplastic resin. Barrier-functional base
material layer 17 is disposed inside of adhesive layer 12 and
adhered to adhesive layer 12. The above "main component" means a
component contained in an amount of 50 mass % (weight %) or
more.
[0022] It is preferable that the first barrier-functional resin as
the main component of fuel permeation preventing layer 11 is vinyl
alcohol resin and/or vinyl alcohol-based copolymer resin which is
excellent in barrier characteristics to permeable fuel containing
alcohol. Particularly, the barrier characteristics can be
sufficiently exhibited by using polyvinyl alcohol resin (referred
to as "PVOH" hereafter), ethylene-vinyl alcohol copolymer resin
(referred to as "EVOH"), and/or a blend of PVOH and EVOH.
[0023] Base material layer 18 and barrier-functional base material
layer 17 are intended to maintain a strengths of the fuel container
such as an impact resistance. The thermoplastic resin as the main
component of base material layer 18 and barrier-functional base
material layer 17 is preferably olefin resin, more preferably
polyethylene resin which is advantageous from the viewpoints of
impact-resistance, availability and cost.
[0024] Barrier-functional base material layer 17 contains a second
barrier-functional resin which is lamina-like and dispersed in the
matrix or thermoplastic resin of barrier-functional base material
17. The second barrier-functional resin is homogeneous with the
first barrier-functional resin as the main component of the fuel
permeation preventing layer 11. Therefore, the second
barrier-functional resin is preferably vinyl alcohol resin or vinyl
alcohol-based copolymer resin, more preferably polyvinyl alcohol
resin (PVOH), ethylene-vinyl alcohol copolymer resin (EVOH), and/or
the blend of PVOH and EVOH.
[0025] The lamina-like second barrier-functional resin has a
maximum length (or dimension of the longest portion) of preferably
not less than 5 mm, more preferably not less than 10 mm, and a
maximum thickness (or dimension of the thickest portion) of
preferably not less than 10 .mu.m, more preferably not less than 15
.mu.m. It is preferable that the barrier-functional base material
layer 17 contains 2 to 12 mass % (weight %) of the second
barrier-functional resin.
[0026] Reason for setting the above maximum length and thickness of
the second barrier-functional resin will be discussed. If the
maximum length of the second barrier-functional resin is less than
5 mm, an interrupting performance to the permeable fuel may be
degraded according to the content and the like of the second
barrier-functional resin in the barrier-functional base material
layer 17. It is made possible to more securely obtain the
interrupting performance to the permeable fuel by setting the
maximum length at a value of not less than 5 mm. If the maximum
thickness is less than 10 .mu.m, the interrupting performance to
the permeable fuel may be degraded according to the content and the
like of the second barrier-functional resin. It is made possible to
more securely obtain the interrupting performance to the permeable
fuel by setting the maximum thickness at a value of not less than
10 .mu.m.
[0027] Reason for setting the above content of the second
barrier-functional resin will be discussed. If the content of the
second barrier-functional resin is less than 2 mass %, the
interrupting performance to the permeable fuel may be degraded. If
the content exceeds 12 mass %, the strength of the
barrier-functional base material layer 17 may be insufficient.
Thus, both the interrupting performance to the permeable fuel and
the strength of the barrier-functional base material layer 17 can
be securely obtained by setting the content of the second
barrier-functional resin at a value of 2 to 12 mass %. The content
of the second barrier-functional resin is more preferably 3 to 10
mass %, the most preferably 3 to 7 mass %.
[0028] The above fuel container is produced by blow-molding a
multi-layered parison. More specifically, the parison having fuel
permeation preventing layer 11, two adhesive layers 12, 14, base
material layer 18 and barrier-functional base material layer 17 is
extruded by an extruder. The parison is then put between two halves
of an open blow mold, and thereafter the blow mold is closed,
followed by expanding the parison within the blow mold with
pressurized air so as to form the parison into a certain shape.
Here, during the above blow molding, when the parison is put
between the two halves of the blow molding to form pinch-off areas
each of which is pinched by portions of the respective two halves
of the blow molding, fuel permeation preventing layer 11 located at
the central position of the five layers 17, 12, 11, 14, 18 may
become in a condition of being cut so as to form a clearance as
shown in FIG. 5. However, the lamina-like second barrier-functional
resin having a function to prevent fuel permeation is dispersed in
the permeation preventing layer 11, and therefore the fuel
container can be effectively prevented from fuel permeation made
around the pinch-off areas under the action of the second
barrier-functional resin.
[0029] Thus, the fuel container can obtain an interrupting
performance to fuel permeation made around the pinch-off areas
under the action of barrier-functional base material 17 containing
the second barrier-functional resin without degrading advantages of
the plastic-made fuel container. Additionally, by virtue of fuel
permeation preventing layer 11 and barrier-functional base material
layer 17, the interrupting performance to fuel permeation through
the whole fuel container can be further improved. Furthermore,
since the EVOH resin and/or the PVOH is used as the second
barrier-functional resin, the fuel container is very effective for
preventing fuel permeation not only in case of being filled with
usual gasoline but also in case of being filled with gasoline mixed
with alcohol.
[0030] In general, when a fuel container of an automotive vehicle
is blow-molded, a surplus or excess material (the surplus of the
parison separated from the blow-molded fuel container) formed
during a blow molding process of the fuel container reach to 30 to
50% in weight of a fuel container or tank. Accordingly, the surplus
materials are recycled in the blow molding process. In this regard,
fuel container has base material layer 18 and barrier-functional
base material layer 17 which are the same in their main component,
and the second barrier-functional resin contained in
barrier-functional base material 17 is homogeneous with the first
barrier-functional resin as the main component of fuel permeation
preventing layer 11. As a result, chemical reactions can be
prevented from occurring when the resins are molten and kneaded in
the extruder, and therefore there is no problem of the physical
properties of recycled materials being degraded, thus making it
possible to stably recycle the reminder materials formed in the
blow molding process.
[0031] In the blow molding of the fuel container, the EVOH resin
and/or the PVOH resin is blended to the main component of the
barrier-functional base material layer 17 in a state of dry blend
or by only changing a screw in the extruder to form the
barrier-functional base material layer 17. Accordingly, an existing
production equipment for fuel container can be used as it is
thereby making it possible to produce the super low fuel-permeable
fuel container under inexpensive facility investment.
[0032] Since the fuel container has an outermost layer which is
base material layer 18 as shown in FIG. 1, the outermost layer can
be prevented from cracking when impact is applied to the outermost
layer from outside. Additionally, in case that plastic parts such
as piping and connectors are welded to the outer surface of the
outermost layer, stable weldability of the plastic parts can be
obtained.
[0033] FIG. 2 illustrates a fragmentary section of a second
embodiment of the fuel container according to the present
invention, similar to that of the first embodiment. In this second
embodiment, the fuel container comprises fuel permeation preventing
layer 11 whose main component is the first barrier-functional
resin. Adhesive layers 12, 14 are disposed on the opposite sides of
fuel permeation preventing layer 11 and adhered to fuel permeation
preventing layer 11. Adhesive layer 14 is disposed outside of the
fuel permeation preventing layer 11. Barrier-functional base
material layer 17 containing the dispersed lamina-like second
barrier-functional resin is disposed outside of adhesive layer 14
and adhered to adhesive layer 14. Base material layer 18 is
disposed outside of barrier-functional base material layer 17 and
adhered to barrier-functional base material layer 17. Another base
material layer 18 is disposed inside of adhesive layer 12 and
adhered to adhesive layer 12. Thus, the fuel container of this
embodiment takes a six-layer structure.
[0034] With the fuel container of this embodiment, the same
advantageous effects as those of the fuel container of the first
embodiment can be obtained. Additionally, since the outermost layer
is base material layer 18, the outermost layer can be prevented
from cracking when impact is applied to the outermost layer from
outside. Further, stable weldability of the plastic parts to the
outer surface of the outermost layer can be obtained.
[0035] FIG. 3 illustrates a fragmentary section of a third
embodiment of the fuel container according to the present
invention, similar to that of the first embodiment. In this third
embodiment, the fuel container comprises fuel permeation preventing
layer 11 whose main component is the first barrier-functional
resin. Adhesive layers 12, 14 are disposed on the opposite sides of
fuel permeation preventing layer 11 and adhered to fuel permeation
preventing layer 11. Adhesive layer 14 is disposed outside of the
fuel permeation preventing layer 11 and adhered to fuel permeation
preventing layer 11. Barrier-functional base material layer 17
containing the dispersed lamina-like second barrier-functional
resin is disposed outside of adhesive layer 14 and adhered to
adhesive layer 14. Base material layer 18 is disposed inside of
adhesive layer 14 and adhered to adhesive layer 12. Thus, the fuel
container of this embodiment takes a five-layer structure.
[0036] With the fuel container of this embodiment, similarly to the
above embodiments, the interrupting performance to fuel permeation
made around the pinch-off areas formed during the blow molding can
be effectively obtained while ensuring the interrupting performance
to fuel permeation through the whole fuel container. Additionally,
since the innermost layer is the base material layer 18, the
innermost layer can be prevented from cracking when impact is
applied from outside.
[0037] In case that the fuel container is used as a fuel tank of an
automotive vehicle, the fuel container is formed with an opening A
as shown in FIG. 6 in order to install a part P such as a pump, a
piping or a connector. Here, if the fuel container takes the
structure shown in FIG. 3 where barrier-functional base material
layer 17 is disposed outside of the fuel permeation preventing
layer 11, permeation of the permeable fuel to the outside of the
fuel container can be effectively suppressed by virtue of the
second barrier-functional resin dispersed in barrier-functional
base material 17 even if the permeable fuel permeates through a
wall surface (of the fuel container) defining the opening A.
[0038] FIG. 4 illustrates a fragmentary section of a fourth
embodiment of the fuel container according to the present
invention, similar to that of the first embodiment. In this fourth
embodiment, the fuel container comprises fuel permeation preventing
layer 11 whose main component is the first barrier-functional
resin. Adhesive layers 12, 14 are disposed on the opposite sides of
fuel permeation preventing layer 11 and adhered to fuel permeation
preventing layer 11. Adhesive layer 14 is disposed outside of fuel
permeation preventing layer 11 and adhered to fuel permeation
preventing layer 11. Barrier-functional base material layer 17
containing the dispersed lamina-like second barrier-functional
resin is disposed outside of adhesive layer 14 and adhered to
adhesive layer 14. Base material layer 18 is disposed outside of
barrier-functional base material layer 17 and adhered to
barrier-functional base material layer 17. Another
barrier-functional base material layer 17 containing the dispersed
lamina-like second barrier-functional resin is disposed inside of
adhesive layer 12 and adhered to adhesive layer 12. Thus, the fuel
container of this embodiment takes a six-layer structure.
[0039] With the fuel container of this embodiment, since two
barrier-functional base material layers 17, 17 are provided, the
interrupting performance to fuel permeation made around the
pinch-off areas formed during the blow molding can be further
improved while improving the preventing ability for fuel permeation
through the whole fuel container. Additionally, the outermost layer
is the base material layer 18, and therefore the outermost layer
can be prevented from cracking when impact is applied to the
outermost layer from outside, while improving the weldability of
plastic parts to the fuel container.
[0040] While examples of basic arrangements of the fuel container
according to the present invention have been shown and described in
FIGS. 1 to 4, it will be understood that arrangements other than
those basic arrangements may be applied to the fuel container, in
which the number, thickness and disposition of the layers
constituting of the fuel container are freely selectable according
to required fuel barrier performance and impact resistance of the
fuel container.
EXAMPLES
[0041] The present invention will be more readily understood with
reference to the following Examples in comparison with Comparative
Examples; however, these Examples are intended to illustrate the
invention and are not to be construed to limit the scope of the
invention.
Example 1
[0042] A fuel container was produced having a layer structure as
shown in FIG. 1 by blow molding. The fuel container included a fuel
permeation preventing layer whose main component was EVOH resin
which was available from Kuraray Co., Ltd. under the trade name of
Eval F101B. First and second adhesive layers were disposed on the
opposite sides of the fuel permeation preventing layer and adhered
to the fuel permeation preventing layer. The adhesive layers were
formed of maleic anhydride-modified polyethylene available from
Japan Polyethylene Corporation under the trade name of FT61AR3. The
first adhesive layer was disposed outside of fuel permeation
preventing layer and adhered to the fuel permeation preventing
layer. A base material layer as an outermost layer was disposed
outside of the first adhesive layer and adhered to the first
adhesive layer. The base material layer was formed of high density
polyethylene available from Japan Polyethylene Corporation under
the trade name of KBY47C. A barrier-functional base material layer
as an innermost layer was disposed inside of the second adhesive
layer and adhered to the second adhesive layer. The
barrier-functional base material contained the high density
polyethylene as a main component, and 8.0 mass % of
barrier-functional resin mixture containing 4.0 mass % of
lamina-like barrier-functional resin (PVOH resin) and 4.0 mass % of
a dispersant (for the barrier-functional resin) and the like so
that the lamina-like barrier-functional resin was dispersed in the
main component. The barrier-functional resin mixture was available
from DuPont under the trade name of RB425, in which the lamina-like
barrier-functional resin had the maximum length of not less than 5
mm and the maximum thickness of not less than 10 .mu.m.
[0043] The barrier-functional base material layer had a thickness
of 2.0 mm. The second adhesive layer had a thickness of 0.1 mm. The
fuel permeation preventing layer had a thickness of 0.1 mm. The
first adhesive layer had a thickness of 0.1 mm. The base material
layer had a thickness of 3.7 mm. The produced fuel container had a
thickness of 6.0 mm and a volume of 60 liters, and took a
five-layer structure.
Example 2
[0044] A fuel container was produced having a layer structure as
shown in FIG. 2 by blow molding. The fuel container included a fuel
permeation preventing layer. First and second adhesive layers were
disposed on the opposite sides of the fuel permeation preventing
layer and adhered to the fuel permeation preventing layer. The
first adhesive layer was disposed outside of the fuel permeation
preventing layer and adhered to the fuel permeation preventing
layer. A barrier-functional base material layer was disposed
outside of the first adhesive layer and adhered to the first
adhesive layer. A first base material layer as an outermost layer
was disposed outside of the barrier-functional base material layer
and adhered to the barrier-functional base material layer. The
second adhesive layer was disposed inside of the fuel permeation
preventing layer and adhered to the fuel permeation preventing
layer. A second base material layer as an innermost layer was
disposed inside of the second adhesive layer and adhered to the
second adhesive layer.
[0045] The barrier-functional base material layer, the first and
second adhesive layers, the fuel permeation preventing layer and
the base material layer were respectively formed of the same
materials as those of the corresponding layers in Example 1.
[0046] The second base material layer had a thickness of 2.0 mm.
The second adhesive layer had a thickness of 0.1 mm. The fuel
permeation preventing layer had a thickness of 0.1 mm. The first
adhesive layer had a thickness of 0.1 mm. The barrier-functional
base material had a thickness of 2.7 mm. The first base material
layer had a thickness of 1.0 mm. The produced fuel container had a
thickness of 6.0 mm and a volume of 60 liters, and took a six-layer
structure.
Example 3
[0047] A fuel container was produced having a layer structure as
shown in FIG. 3 by blow molding. The fuel container included a fuel
permeation preventing layer. First and second adhesive layers were
disposed on the opposite sides of the fuel permeation preventing
layer and adhered to the fuel permeation preventing layer. The
first adhesive layer was disposed outside of the fuel permeation
preventing layer and adhered to the fuel permeation preventing
layer. A barrier-functional base material layer as an outermost
layer was disposed outside of the first adhesive layer and adhered
to the first adhesive layer. The second adhesive layer was disposed
inside of the fuel permeation preventing layer and adhered to the
fuel permeation preventing layer. A base material layer as an
innermost layer was disposed inside of the second adhesive layer
and adhered to the second adhesive layer.
[0048] The barrier-functional base material layer, the first and
second adhesive layers, the fuel permeation preventing layer and
the base material layer were respectively formed of the same
materials as those of the corresponding layers in Example 1.
[0049] The base material layer had a thickness of 2.0 mm. The
second adhesive layer had a thickness of 0.1 mm. The fuel
permeation preventing layer had a thickness of 0.1 mm. The first
adhesive layer had a thickness of 0.1 mm. The barrier-functional
base material had a thickness of 3.7 mm. The produced fuel
container had a thickness of 6.0 mm and a volume of 60 liters, and
took a five-layer structure.
Example 4
[0050] A fuel container was produced having a layer structure as
shown in FIG. 4 by blow molding. The fuel container included a fuel
permeation preventing layer. First and second adhesive layers were
disposed on the opposite sides of the fuel permeation preventing
layer and adhered to the fuel permeation preventing layer. The
first adhesive layer was disposed outside of the fuel permeation
preventing layer and adhered to the fuel permeation preventing
layer. A first barrier-functional base material layer was disposed
outside of the first adhesive layer and adhered to the first
adhesive layer. A base material layer as an outermost layer was
disposed outside of the first barrier-functional base material
layer and adhered to the first barrier-functional base material
layer. The second adhesive layer was disposed inside of the fuel
permeation preventing layer and adhered to the fuel permeation
preventing layer. A second barrier-functional base material layer
as an innermost layer was disposed inside of the second adhesive
layer and adhered to the second adhesive layer.
[0051] The barrier-functional base material layer, the first and
second adhesive layers, the fuel permeation preventing layer and
the base material layer were respectively formed of the same
materials as those of the corresponding layers in Example 1.
[0052] The second barrier-functional base material layer had a
thickness of 2.0 mm. The second adhesive layer had a thickness of
0.1 mm. The fuel permeation preventing layer had a thickness of 0.1
mm. The first adhesive layer had a thickness of 0.1 mm. The first
barrier-functional base material layer had a thickness of 2.7 mm.
The base material layer had a thickness of 1.0 mm. The produced
fuel container had a thickness of 6.0 mm and a volume of 60 liters,
and took a six-layer structure.
Example 5
[0053] The procedure of Example 2 was repeated to produce a fuel
container of this Example having a layer structure as shown in FIG.
2 by blow molding, with the exception that the barrier-functional
base material contained 4.0 mass % of the barrier-functional resin
mixture containing 2.0 mass % of the lamina-like barrier-functional
resin (PVOH resin) and 2.0 mass % of the dispersant and the
like.
Example 6
[0054] The procedure of Example 2 was repeated to produce a fuel
container of this Example having a layer structure as shown in FIG.
2 by blow molding, with the exception that the barrier-functional
base material contained 12.0 mass % of the lamina-like
barrier-functional resin (PVOH resin) and 12.0 mass % of the
dispersant and the like.
Example 7
[0055] The procedure of Example 2 was repeated to produce a fuel
container of this Example having a layer structure as shown in FIG.
2 by blow molding, with the exception that the lamina-like
barrier-functional resin (PVOH) contained in the barrier-functional
base material had the maximum length of 3 mm (in maximum
value).
Example 8
[0056] The procedure of Example 2 was repeated to produce a fuel
container of this Example having a layer structure as shown in FIG.
2 by blow molding, with the exception that the lamina-like
barrier-functional resin (PVOH) contained in the barrier-functional
base material had the maximum thickness of 5 .mu.m (in maximum
value).
Comparative Example 1
[0057] A fuel container was produced by blow molding. The fuel
container included a fuel permeation preventing layer. First and
second adhesive layers were disposed on the opposite sides of the
fuel permeation preventing layer and adhered to the fuel permeation
preventing layer. The first adhesive layer was disposed outside of
the fuel permeation preventing layer and adhered to the fuel
permeation preventing layer. A first base material layer as an
outermost layer was disposed outside of the first adhesive layer
and adhered to the first adhesive layer. The second adhesive layer
was disposed inside of the fuel permeation preventing layer and
adhered to the fuel permeation preventing layer. A second base
material layer as an innermost layer was disposed inside of the
second adhesive layer and adhered to the second adhesive layer.
[0058] The first and second adhesive layers, the fuel permeation
preventing layer and the base material layer were respectively
formed of the same materials as those of the corresponding layers
in Example 1.
[0059] The second base material layer had a thickness of 2.0 mm.
The second adhesive layer had a thickness of 0.1 mm. The fuel
permeation preventing layer had a thickness of 0.1 mm. The first
adhesive layer had a thickness of 0.1 mm. The first base material
layer had a thickness of 3.7 mm. The produced fuel container had a
thickness of 6.0 mm and a volume of 60 liters, and took a
five-layer structure including no barrier-functional base material
layer of the present invention.
Comparative Example 2
[0060] The procedure of Example 2 was repeated to produce a fuel
container of this Example having a layer structure as shown in FIG.
2 by blow molding, with the exception that the barrier-functional
base material contained 1.0 mass % of the lamina-like
barrier-functional resin (PVOH resin) and 1.0 mass % of the
dispersant and the like.
Comparative Example 3
[0061] The procedure of Example 2 was repeated to produce a fuel
container of this Example having a layer structure as shown in FIG.
2 by blow molding, with the exception that the barrier-functional
base material contained 15.0 mass % of the lamina-like
barrier-functional resin (PVOH resin) and 15.0 mass % of the
dispersant and the like.
Comparative Example 4
[0062] The procedure of Example 2 was repeated to produce a fuel
container of this Example having a layer structure as shown in FIG.
2 by blow molding, with the exception that the lamina-like
barrier-functional resin in the barrier-functional base material
was nylon-based and available from DuPont under the trade name of
RB901. The barrier-functional base material contained 4.0 mass % of
the lamina-like barrier-functional resin and 4.0 mass % of the
dispersant and the like.
[0063] Evaluation Test
[0064] In order to evaluate performances of the fuel containers of
Examples and Comparative Examples, tests for evaluating fuel
permeation preventing characteristics, low temperature
impact-resistance and surplus material recycling characteristics
were conducted.
[0065] Fuel Permeation Preventing Characteristics
[0066] The fuel container produced by the blow molding and having a
volume of 60 liters was filled with a fuel and allowed to stand in
an atmosphere of 40.degree. C., in which a fuel permeation amount
(the amount of the fuel to be emitted out of the fuel container)
was measured at the intervals of 500 hours until the fuel
permeation amount was saturated. This measurement was conducted by
using a VT-SHED (Variable Temperature--Sealed Housing for
Evaporative Emissions) which was available from JAPS corporation.
The fuel used in this measurement was a mixture of Indolene and
ethanol, in which the ethanol was contained in an amount of 10 vol.
% based on the Indolene. The Indolene was a standard test fuel
approved by EPA (Environmental Protection Agency) in U.S.A.
[0067] Low Temperature Impact Resistance
[0068] A test piece having a dimension of 6 mm thickness, 65 mm
length and 65 mm width was cut out from a flat wall section of the
fuel container produced by the blow molding. The test piece was
subjected to a high-speed surface impact test using a high-speed
surface impact tester available from Shimadzu Corporation. The
high-speed surface impact test was conducted according to ASTM
D3763 and under a condition where the temperature of an atmosphere
was -40.degree. C.; the diameter of a dart was {fraction (1/2)}
inch; and the speed of the dart was 11.1 m/s, thereby measuring an
impact energy for evaluating an impact-resistance.
[0069] Surplus Material Recycling Characteristics
[0070] (a) Impact-Resistance of Recycled Surplus Material
[0071] The fuel container produced by the blow molding was
pulverized and re-pelletized to form pellets. The thus formed
pellets were thermo-pressed to produce a test piece having a
dimension of 3 mm thickness, 65 mm length and 65 mm width. The test
piece was subjected to a high-speed surface impact test using a
high-speed surface impact tester available from Shimadzu
Corporation. The high-speed surface impact test was conducted
according to ASTM D3763 and under a condition where the temperature
of an atmosphere was -40.degree. C.; the diameter of a dart was
{fraction (1/2)} inch; and the speed of the dart was 11.1 m/s,
thereby measuring an impact energy for evaluating an
impact-resistance.
[0072] (b) Kneading Stability of Recycled Surplus Material
[0073] In order to evaluate a kneading stability of the recycled
surplus material, the pulverized fuel container was kneaded in a
laboratory plastomill in the atmosphere of air at 230.degree. C.
for 1 hour to measure a torque change of the plastomill.
[0074] Results of the above evaluation tests are shown in Table 1.
Concerning the fuel permeation preventing characteristics and the
low temperature impact resistance of the fuel container, and the
impact resistance of the recycled surplus material, those of
Comparative Example 1 are taken as standards, in which those
excellent as compared with the standards are indicated by "A";
those generally equivalent to the standards are indicated by "B";
and those inferior as compared with the standards are indicated by
"C". Concerning the kneading stability of the recycled surplus
material, if the torque change falls within .+-.20% for a time from
first time point (5 minutes from the initiation of the kneading) to
a second time point (60 minutes from the initiation of the
kneading), an evaluation is such that the kneading stability is
sufficient and indicated by "A". If the torque change does not fall
within .+-.20%, an evaluation is such that the kneading stability
is insufficient and indicated by "B". Concerning a total
evaluation, if the test piece is sufficient in fuel permeation
preventing effect, it is indicated by "A".
1TABLE 1 Low Fuel temp. Impact Kneading permeation impact
resistance stability preventing resistance of of characteristics of
recycled recycled of fuel surplus surplus Total Test piece fuel
container container material material evaluation Example 1 A B B A
A Example 2 A B B A A Example 3 A B B A A Example 4 A B B A A
Example 5 A B B A A Example 6 A B B A A Example 7 A B B A A Example
8 A B B A A Comparative Standard Standard Standard A Standard
example 1 Comparative B B B A Insufficient example 2 in fuel
permeation preventing effect Comparative A C C A Insufficient
example 3 in impact resistance Comparative -- -- -- Torque-up
Difficult in example 4 occurred recycling of surplus material
[0075] As apparent from the evaluation results in FIG. 1, the fuel
containers of Examples 1 to 8 were excellent in fuel permeation
preventing characteristics as compared with the fuel container of
Comparative Example 1 while meeting required performances of low
temperature impact resistance and surplus material recycling
characteristics for fuel containers. The fuel container of Example
7 using the lamina-like resin having the maximum length of 3 mm and
the fuel container of Example 8 using the lamina-like
barrier-functional resin having the maximum thickness of 5 .mu.m
were slightly low in fuel permeation preventing characteristics but
improved in surplus material recycling characteristics as compared
with the fuel containers of Examples 1 to 6 using the lamina-like
barrier-functional resin having the maximum length of not less than
5 mm and the maximum thickness of not less than 10 .mu.m.
[0076] The test results of Examples 2, 5 and 6 and Comparative
Example 2 which were the same in layer structure depicted that the
fuel permeation preventing effect could not be obtained if the
content of the PVOH resin was not more than 1.0 mass % while the
impact resistance of the fuel container and the physical properties
of the recycled surplus material were lowered if the content of the
PVOH resin was not less than 15.0 mass %. Additionally, it would be
appreciated the suitable content range of the PVOH resin was not
less than 2.0 mass % and not more than 12.0 mass %, particularly
from Examples 5 and 6.
[0077] Further, it was confirmed from the test results of Example 2
and Comparative Example 4, that the torque of the laboratory
plastomill was stable in the kneading stability test thereby
providing no problem in the melting and kneading in the surplus
material recycling process in case where the barrier-functional
resin in the barrier-functional base material layer was of vinyl
alcohol-based resin (PVOH resin and/or EVOH resin) which was
homogeneous with that of EVOH resin as the main component of the
fuel permeation preventing layer. In contrast, in case where the
barrier-functional resin in the barrier-functional material layer
was a nylon-based resin, the torque-change occurred in the kneading
stability test thereby making an extrusion of the resin
unstable.
[0078] While the fuel container according to the present invention
has been shown and described in detail with reference to Examples,
it will be understood that the arrangements of the fuel container
according to the present invention are not limited to those of
Examples and therefore a variety of modifications may be made
within the scope of the present invention. For example, from the
viewpoints of materials, in order to improve the barrier-function
of the barrier-functional base material layer, different
barrier-functional resin(s) from and not reactive to the first and
second barrier-functional resins may be blended with the second
barrier-functional resin in such an amount that the total amount of
the different barrier-functional resin(s) and the second
barrier-functional resin was within the preferable range of the
second barrier-functional resin.
[0079] Moreover, it may be made to add an elastomer component in
the barrier-functional base material layer in order to improve the
impact resistance of the fuel container. Additionally, to control a
barrier performance of the fuel container, a dispersant for PVOH
resin or/or EVOH resin may be suitably added to the
barrier-functional base material. Besides, a heat stabilizer, an
oxidation inhibitor, and/or a processing aid may be added to the
barrier-functional base material if necessary.
[0080] As appreciated from the above, according to the present
invention, even if the fuel permeation preventing layer is cut at
the pinch-off area during the blow molding of the parison having
the multi-layer structure including the base material, the
barrier-functional base material layer and the fuel permeation
preventing layer, the preventing performance to fuel permeation
around the pinch-off area can be obtained by virtue of the second
barrier-functional resin dispersed in the thermoplastic resin of
the barrier-functional base material, while improving a total fuel
permeation preventing performance of the fuel container under the
effect of the fuel permeation preventing layer and the
barrier-functional base material layer. As a result, it is
unnecessary to form a cover or a resin coating at the pinch-off
area, and therefore an improvement in fuel permeation preventing
performance can be effectively realized without degrading any
advantages of a plastic-made fuel container, such as being light in
weight, high in freedom in design, excellent in corrosion
resistance and low in cost. Additionally, in the fuel container,
the main components of the base material layer and the
barrier-functional base material layer are the same, and the second
barrier-functional resin is homogeneous with the first
barrier-functional resin. Accordingly, chemical reactions are
prevented from occurring when surplus or excess materials produced
in a production process of the fuel tank are kneaded for recycling
within the production process, thereby providing no fear of
lowering the physical properties of recycled materials. Thus,
recycling of the surplus materials can be readily accomplished with
no problem.
[0081] The entire contents of Japanese Patent Application No.
2004-053531, filed Feb. 27, 2004, are incorporated herein by
reference.
[0082] Although the invention has been described above by reference
to certain embodiments and examples of the invention, the invention
is not limited to the embodiments and examples described above.
Modifications and variations of the embodiments and examples
described above will occur to those skilled in the art, in light of
the above teachings. The scope of the invention is defined with
reference to the following claims.
* * * * *