U.S. patent application number 12/525336 was filed with the patent office on 2010-07-01 for multilayer tube.
Invention is credited to Masatomi Sato.
Application Number | 20100166995 12/525336 |
Document ID | / |
Family ID | 39674077 |
Filed Date | 2010-07-01 |
United States Patent
Application |
20100166995 |
Kind Code |
A1 |
Sato; Masatomi |
July 1, 2010 |
MULTILAYER TUBE
Abstract
There is provided a multilayer resin tube having a plurality of
thermoplastic resin layers, wherein an intermediate layer of the
resin layers comprises an acid modified resin modified by the
introduction of a functional group, and at least one layer is a
barrier layer comprising an aromatic polyamide, for example, PA9T.
The multilayer resin tube has good low-permeability attained with
the use of an inexpensive resin, without using an expensive
highly-functional resin such as a fluororesin.
Inventors: |
Sato; Masatomi;
(Ibaraki-ken, JP) |
Correspondence
Address: |
LADAS & PARRY LLP
26 WEST 61ST STREET
NEW YORK
NY
10023
US
|
Family ID: |
39674077 |
Appl. No.: |
12/525336 |
Filed: |
January 31, 2008 |
PCT Filed: |
January 31, 2008 |
PCT NO: |
PCT/JP2008/051489 |
371 Date: |
November 18, 2009 |
Current U.S.
Class: |
428/36.91 |
Current CPC
Class: |
B32B 2307/546 20130101;
Y10T 428/1393 20150115; B32B 2605/08 20130101; B32B 27/308
20130101; B32B 27/32 20130101; B32B 27/08 20130101; B32B 2307/7242
20130101; B32B 2597/00 20130101; B32B 2307/202 20130101; B32B
2250/24 20130101; B32B 1/08 20130101; B32B 27/34 20130101; F16L
9/12 20130101; B32B 2307/7265 20130101; F16L 11/04 20130101 |
Class at
Publication: |
428/36.91 |
International
Class: |
B32B 1/08 20060101
B32B001/08 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 1, 2007 |
JP |
2007-023520 |
Claims
1. A multilayer resin tube having a multilayer structure of a
plurality of thermoplastic resin layers, wherein an intermediate
layer of the plurality of resin layers comprises an acid modified
resin modified by the introduction of a functional group, and at
least one adjacent layer is a barrier layer comprising an aromatic
polyamide as a main component.
2. A multilayer resin tube having a multilayer structure of three
or more thermoplastic resin layers, said tube having a barrier
layer comprising an aromatic polyamide as a main component, wherein
an outer layer and an inner layer, lying outside and inside the
barrier layer, each comprise an acid modified resin modified by the
introduction of a functional group.
3. The multilayer resin tube according to claim 2, wherein the
barrier layer comprises PA9T.
4. The multilayer resin tube according to claim 3, wherein the
outer layer and the inner layer each comprise an ethylene/GMA
(glycidyl methacrylate) copolymer.
5. A multilayer resin tube having a multilayer structure of three
or more thermoplastic resin layers, said tube comprising a barrier
layer comprising an acid modified aromatic polyamide, modified by
the introduction of a functional group, as a main component, and an
outer resin layer and an inner resin layer, both adjacent to the
barrier layer.
6. The multilayer resin tube according to claim 5, wherein the
barrier layer comprises acid modified PA9T.
7. The multilayer resin tube according to claim 3, wherein the
outer resin layer and the inner resin layer each comprise PA6,
PA66, PA11 or PA12, or a mixture thereof.
8. The multilayer resin tube according to claim 6, wherein the
outer resin layer and the inner resin layer each comprise an acid
modified PE resin.
9. A multilayer resin tube having a multilayer structure of three
or more thermoplastic resin layers, said tube having a layer
comprising an acid modified resin modified by the introduction of a
functional group, wherein an inner layer, lying inside the acid
modified resin layer, is a barrier layer comprising an aromatic
polyamide as a main component.
10. The multilayer resin tube according to claim 9, wherein the
acid modified resin layer comprises an acid modified aromatic PA9T
and the barrier layer comprises PA9T.
11. The multilayer resin tube according to claim 9, wherein the
acid modified resin layer comprises an ethylene/GMA (glycidyl
methacrylate) copolymer, and the barrier layer comprises PA9T or
acid modified PA9T.
12. The multilayer resin tube according to claim 9, wherein the
acid modified resin layer comprises acid modified polyethylene, and
the barrier layer comprises acid modified PA9T.
13. The multilayer resin tube according to claim 10, wherein an
outer layer, lying outside the acid modified resin layer, comprises
PA6, PA66, PA11 or PA 12, or high-density polyethylene (HDPE),
low-density polyethylene (LDPE) or linear low-density
polyethylene.
14. A multilayer resin tube having a multilayer structure of three
or more thermoplastic resin layers, wherein a layer lying inside
the outermost resin layer is a barrier layer comprising an acid
modified aromatic polyamide, modified by the introduction of a
functional group, as a main component.
15. The multilayer resin tube according to claim 10, wherein the
outermost resin layer comprises PA6, PA66, PA11 or PA12, or a
mixture thereof.
16. The multilayer resin tube according to claim 14, wherein the
outermost resin layer comprises an ethylene/GMA (glycidyl
methacrylate) copolymer.
17. The multilayer resin tube according to claim 10, wherein the
outermost resin layer comprises an acid modified PE resin.
18. A multilayer resin tube having a multilayer structure of three
or more thermoplastic resin layers, wherein the outermost resin
layer comprises an acid modified resin modified by the introduction
of a functional group, and a layer lying inside the acid modified
resin layer is a barrier layer comprising an aromatic polyamide as
a main component.
19. The multilayer resin tube according to claim 18, wherein the
outermost resin layer comprises an ethylene/GMA (glycidyl
methacrylate) copolymer.
20. A multilayer resin tube having a multilayer structure of five
or more thermoplastic resin layers, wherein, in order from the
outermost resin layer, the first layer is a PE (polyethylene) resin
layer, the second and fourth layers are each an acid modified PE
(polyethylene) resin layer, the resin being modified by the
introduction of a functional group, and the third or fifth layer is
a barrier layer comprising an aromatic polyamide.
21. The multilayer resin tube according to claim 1, wherein the
innermost layer comprises a crosslinked polyethylene resin.
22. The multilayer resin tube according to claim 1, wherein the
proportion of the acid modified resin(s) (excluding ethylene/GMA
copolymer) in all the resins of the tube is less than 50% by
weight.
23. The multilayer resin tube according to claim 8, wherein the
acid modified PE resin has a tensile breaking strength of not less
than 12 MPa, a breaking elongation of not less than 300% and an MFR
of not less than 0.5 g/min.
24. The multilayer resin tube according to claim 1, wherein the
resin (excluding PA) of the first layer has a density of 0.90 to
1.5 g/cm3, a flexural modulus of not less than 850 MPa and an
environmental stress crack resistance of not less than 200 hr.
25. The multilayer resin tube according to claim 1, wherein the
innermost layer is a conductive resin layer.
Description
TECHNICAL FIELD
[0001] The present invention relates to a multilayer tube for use
as an automotive fuel tube.
BACKGROUND ART
[0002] These days a resin tube is increasingly being used as an
automotive fuel tube. A resin tube has many advantages: Unlike a
metal tube, a resin tube does not rust and is easy to process. In
addition, a resin tube is lightweight and enables a high degree of
design freedom.
[0003] On the other hand, there is a problem in the use of a resin
tube as a fuel tube: Gasoline can permeate the tube and leak out.
From an environmental standpoint, regulations on the fuel
permeability of a resin tube for use as a fuel tube are becoming
increasingly stricter these days in the United States and
Europe.
[0004] The fuel permeability of a resin tube for use as a fuel tube
can be determined by measuring a hydrocarbon permeability in
accordance with CARB DBL test method using a SHED test machine; and
a resin tube is determined to be low fuel-permeable when the
measured hydrocarbon permeability is not more than 50 mg/mday.
[0005] To impart a fuel permeation-resistant property (hereinafter
referred to as "low permeability") to a resin tube for use as a
fuel tube is therefore an urgent problem to be solved. A
low-permeability multilayer resin tube is known which comprises a
low-permeability resin layer in the innermost layer to be in
contact with gasoline and a layer of a polyamide resin or the like
in the outermost layer, with an adhesive layer interposed
therebetween. A fluororesin (ETFE) is known to be very excellent in
the low permeability, and the development of a resin tube
comprising a barrier layer of the fluororesin is now in
progress.
DISCLOSURE OF THE INVENTION
[0006] Though a resin tube comprising a barrier layer of such a
fluororesin is effective in terms of the low permeability, it has
the drawback of the fluororesin being expensive.
[0007] A multilayer resin tube may therefore be considered which
uses a resin which is relatively good in the low permeability and
relatively inexpensive. In fact, attempts have been made to produce
a multilayer resin tube by coextrusion of e.g. inexpensive
polyethylene (PE) with other resin(s). Such a multilayer resin
tube, however, generally has the problem of poor adhesion between
PE and another resin, making it impractical to use the resin tube
as an automotive fuel tube.
[0008] it is therefore an object of the present invention to solve
the above problems in the prior art and provide a multilayer tube
which has good low-permeability attained with the use of an
inexpensive resin, without using an expensive highly-functional
resin such as a fluororesin, and has enhanced adhesion between
resin layers, thus having a sufficient strength.
[0009] In order to achieve the object, the present invention
provides a multilayer resin tube having a multilayer structure of a
plurality of thermoplastic resin layers, wherein an intermediate
layer of the plurality of resin layers comprises an acid modified
resin modified by the introduction of a functional group, and at
least one adjacent layer is a barrier layer comprising an aromatic
polyamide as a main component.
[0010] The present invention also provides a multilayer resin tube
having a multilayer structure of three or more thermoplastic resin
layers, said tube having a barrier layer comprising an aromatic
polyamide as a main component, wherein an outer layer and an inner
layer, lying outside and inside the barrier layer, each comprise an
acid modified resin modified by the introduction of a functional
group.
[0011] The present invention also provides a multilayer resin tube
having a multilayer structure of three or more thermoplastic resin
layers, said tube comprising a barrier layer comprising an acid
modified aromatic polyamide, modified by the introduction of a
functional group, as a main component, and an outer resin layer and
an inner resin layer, both adjacent to the barrier layer.
[0012] The present invention also provides a multilayer resin tube
having a multilayer structure of three or more thermoplastic resin
layers, said tube having a layer comprising an acid modified resin
modified by the introduction of a functional group, wherein an
inner layer, lying inside the acid modified resin layer, is a
barrier layer comprising an aromatic polyamide as a main
component.
[0013] The present invention also provides a multilayer resin tube
having a multilayer structure of three or more thermoplastic resin
layers, wherein a layer lying inside the outermost resin layer is a
barrier layer comprising an acid modified aromatic polyamide,
modified by the introduction of a functional group, as a main
component.
[0014] The present invention also provides a multilayer resin tube
having a multilayer structure of three or more thermoplastic resin
layers, wherein the outermost resin layer comprises an acid
modified resin modified by the introduction of a functional group,
and a layer lying inside the acid modified resin layer is a barrier
layer comprising an aromatic polyamide as a main component.
[0015] The present invention also provides a multilayer resin tube
having a multilayer structure of five or more thermoplastic resin
layers, wherein, in order from the outermost resin layer, the first
layer is a PE (polyethylene) resin layer, the second and fourth
layers are each an acid modified PE (polyethylene) resin layer, the
resin being modified by the introduction of a functional group, and
the third or fifth layer is a barrier layer comprising an aromatic
polyamide.
[0016] According to the multilayer tube of the present invention,
good low-permeability can be attained with the use of an
inexpensive resin, without using an expensive highly-functional
resin such as a fluororesin and, in addition, adhesion between
resin layers can be enhanced, thereby securing a sufficient
strength.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a cross-sectional diagram illustrating a
multilayer tube according to a first embodiment of the present
invention;
[0018] FIG. 2 is a cross-sectional diagram illustrating a
multilayer tube according to a second embodiment of the present
invention;
[0019] FIG. 3 is a cross-sectional diagram illustrating a
multilayer tube according to a third embodiment of the present
invention; and
[0020] FIG. 4 is a cross-sectional diagram illustrating a
multilayer tube according to a fourth embodiment of the present
invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0021] Preferred embodiments of the multilayer tube of the present
invention will now be described with reference to the drawings.
First Embodiment
[0022] FIG. 1 shows a cross-section of a multilayer resin tube
according to a first embodiment of the present invention. The
multilayer resin tube, produced by coextrusion, is comprised of
three resin layers: in order from the outermost layer, the first
layer, the second layer and the third layer. The outer first layer
is a resin layer to retain the strength of the tube and enhance the
low-temperature impact resistance. The intermediate second layer is
a barrier layer, composed of an aromatic polyamide (preferably
polyamide 9T, 6T, etc.), to impart low fuel permeability to the
resin tube. The first and third layers are each composed of an acid
modified resin modified by the introduction of a functional group.
The intermediate second layer is preferably composed of an acid
modified PA9T modified e.g. with phthalic anhydride, maleic
anhydride, naphthalene acid or carboxylic acid.
[0023] The outer first layer and the inner third layer are each
preferably composed of an ethylene/GMA (glycidyl methacrylate)
copolymer or an acid modified PE (polyethylene) modified e.g. with
phthalic anhydride, maleic anhydride, naphthalene acid or
carboxylic acid. The acid modified polyethylene preferably has an
MFR viscosity of 0.03 to 5.0 g/10 min.
[0024] According to the first embodiment, the intermediate second
layer can be made to function as a barrier layer having low fuel
permeability with the use of a relatively inexpensive aromatic
polyamide, such as PA9T, as a material. In addition, by using an
acid modified resin for the first and third layers, an adhesion
reaction by the functional group of the acid modified resin can be
caused between the first layer and the second layer and between the
second layer and the third layer, whereby the resin layers can be
made to more strongly adhere to each other. Thus, in addition to
the use of an inexpensive polyethylene-based resin in the first and
third layers, the multilayer resin tube is provided with enhanced
adhesion between the resin layers as well as a good fuel barrier
function. The multilayer rein tube can possess barrier properties
comparable to those obtained by the use of an expensive
highly-functional resin, such as a fluororesin, while attaining a
significant cost reduction in mass production by the use of
inexpensive resin materials.
[0025] In a variation of the first embodiment, the intermediate
second layer may be composed of an acid modified PA9T. In that
case, the first and third layers may be composed of polyamide 6,
polyamide 66, polyamide 11, polyamide 12 or a copolymer of
polyamide 6 and polyamide 12. Alternatively, the first and third
layers may preferably be composed of an ethylene/GMA (glycidyl
methacrylate) copolymer or an acid modified PE (polyethylene)
modified e.g. with phthalic anhydride, maleic anhydride,
naphthalene acid or carboxylic acid.
[0026] In the multilayer resin tube having the second layer of acid
modified PA9T, the first layer and the second layer, and also the
second layer and the third layer attract each other through their
functional groups. The adhesion strength between the resin layers
can therefore be further enhanced.
Second Embodiment
[0027] FIG. 2 shows a multilayer tube according to a second
embodiment of the present invention.
[0028] In the second embodiment, the intermediate second layer of
the three resin layers is composed of an acid modified resin
modified by the introduction of a functional group, and the inner
third layer is a barrier layer composed of an aromatic polyamide
(preferably polyamide 9T or 6T).
[0029] The intermediate second layer may be composed of an acid
modified PA9T (polyamide 9T) modified e.g. with phthalic anhydride,
maleic anhydride, naphthalene acid or carboxylic acid, an
ethylene/GMA (glycidyl methacrylate) copolymer or an acid modified
PE (polyethylene) (MFR value: 0.03 to 5.0 g/10 min).
[0030] The outer first layer is composed of a PE (polyethylene)
resin or a polyamide (PA) resin. The polyethylene of the first
layer preferably is high-density polyethylene (HDPE), low-density
polyethylene (LDPE) or linear low-density polyethylene.
[0031] According to the second embodiment, the inner third layer
can be made to function as a barrier layer having low fuel
permeability with the use of a relatively inexpensive aromatic
polyamide as a material. In addition, by using an acid modified
resin for the second layer, an adhesion reaction by the functional
group of the acid modified resin can be caused between the first
layer and the second layer and between the second layer and the
third layer, whereby the resin layers can be made to more strongly
adhere to each other. Thus, in addition to the use of an
inexpensive polyethylene-based resin, etc. in the first and second
layers, the multilayer resin tube is provided with enhanced
adhesion between the resin layers as well as a good fuel barrier
function. The multilayer rein tube can possess barrier properties
comparable to those obtained by the use of an expensive
highly-functional resin, such as a fluororesin, while attaining a
significant cost reduction in mass production by the use of
inexpensive resin materials. Further, when an acid modified PA9T is
used for the third layer, the second layer and the third layer
attract each other through their functional groups. The adhesion
strength between the two layers can therefore be further
enhanced.
Third Embodiment
[0032] FIG. 3 shows a multilayer tube according to a third
embodiment of the present invention.
[0033] In the third embodiment, the intermediate second layer of
the three resin layers is a barrier layer composed of an aromatic
polyamide [preferably acid modified PA9T (polyamide 9T) modified
e.g. with phthalic anhydride, maleic anhydride, naphthalene acid or
carboxylic acid].
[0034] The outermost first layer may be composed of an ethylene/GMA
(glycidyl methacrylate) copolymer or an acid modified PE
(polyethylene) (MFR value: 0.03 to 5.0 g/10 min).
[0035] Alternatively, the outermost first layer may be composed of
a PE (polyethylene) resin or a polyamide resin (polyamide 6,
polyamide 66, polyamide 11, polyamide 12 or a copolymer of
polyamide 6 and polyamide 12). The polyethylene of the first layer
preferably is high-density polyethylene (HDPE), low-density
polyethylene (LDPE) or linear low-density polyethylene.
[0036] According to the third embodiment, the intermediate second
layer can be made to function as a barrier layer having low fuel
permeability with the use of a relatively inexpensive aromatic
polyamide as a material. In addition, by using an acid modified
resin for the outermost first layer, an adhesion reaction by the
functional group of the acid modified resin can be caused between
the first layer and the second layer, whereby these layers can be
made to more strongly adhere to each other. Thus, in addition to
the use of an inexpensive polyethylene-based resin, etc. in the
first layer, the multilayer resin tube is provided with enhanced
adhesion between the resin layers as well as a good fuel barrier
function. The multilayer rein tube can possess barrier properties
comparable to those obtained by the use of an expensive
highly-functional resin, such as a fluororesin, while attaining a
significant cost reduction in mass production by the use of
inexpensive resin materials.
Fourth Embodiment
[0037] FIG. 4 shows a multilayer tube according to a fourth
embodiment of the present invention.
[0038] The multilayer resin tube has a five-layer structure in
which, in order from the outermost resin layer, the first layer is
a PE (polyethylene) resin layer, the second and fourth layers are
each an acid modified PE (polyethylene) resin layer, the resin
being modified by the introduction of a functional group, and the
third or fifth layer is a barrier layer composed of an aromatic
polyamide (preferably polyamide 9T or 6T).
[0039] According to the fourth embodiment, the third or fifth layer
can be made to function as a barrier layer having low fuel
permeability with the use of a relatively inexpensive aromatic
polyamide as a material. In addition, by interposing an acid
modified PE resin between the first and third layers and between
the third and fifth layers, an adhesion reaction by the functional
group of the acid modified PE resin can be caused between the resin
layers, whereby the resin layers can be made to strongly adhere to
each other despite the use of at least three PE layers. Thus, in
addition to the use of an inexpensive polyethylene-based resin,
etc., the multilayer resin tube is provided with enhanced adhesion
between the resin layers as well as a good fuel barrier function.
The multilayer rein tube can possess barrier properties comparable
to those obtained by the use of an expensive highly-functional
resin, such as a fluororesin, while attaining a significant cost
reduction in mass production by the use of inexpensive resin
materials.
[0040] In the above-described first to fourth embodiments, a
conductive filler may be added to the innermost layer to impart
electrical conductivity to the tube. Carbon nanotubes, carbon black
or carbon fibers can preferably be used as the conductive filler.
The amount of the conductive filler is generally 5 to 30% by weight
based on 100% by weight of the raw materials. If the amount of the
conductive filler is less than 5%, it is difficult to obtain a
surface resistivity of not more than 10E6 .OMEGA./sq which is
necessary for a fuel tube. If the amount exceeds 30% by weight, on
the other hand, there may be a considerable lowering of the
strength.
Examples
[0041] Table 1 shows specific examples of resins usable for the
respective layers of multilayer resin tubes according to the
present invention. In Table 1, Examples 1 to 4 correspond to the
first embodiment, Examples 5 to 8 correspond to the second
embodiment, and Examples 9 and 10 correspond to the fourth
embodiment.
TABLE-US-00001 TABLE 1 Ex. No. 1st layer 2nd layer 3rd layer 4th
layer 5th layer 1 PA6 Modified PE PA9T -- -- 2 Ethylene/GMA PA9T
Ethylene/GMA -- -- 3 Ethylene/GMA Modified PA9T Ethylene/GMA -- --
4 Modified PE Modified PA9T Modified PE -- -- 5 PA Modified PA9T
Cond. PA9T -- -- 6 PE Ethylene/GMA PA9T -- -- 7 PE Ethylene/GMA
Modified PA9T -- -- 8 PE Modified PE Modified PA9T -- -- 9 PE
Modified PE PA9T Modified PE PE 10 PE Modified PE PA Modified PE
PA9T
[0042] In Examples 1, 3, 4 and 7 to 10, the proportion of the acid
modified resin(s) (excluding ethylene/GMA copolymer) in all the
resins of the tube is less than 50% by weight. In Examples 4, 9 and
10, the modified PE resin has a tensile breaking strength of not
less than 12 MPa, a breaking elongation of not less than 300% and
an MFR of not less than 0.5 g/min.
[0043] In the Examples (excluding Examples 1 and 5), the resins for
the first layer has a density of 0.90 to 1.5 g/cm3, a flexural
modulus of not less than 850 MPa and an environmental stress crack
resistance of not less than 200 hr.
* * * * *