Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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The present invention relates to a rubber hose
- having oil-resistant internal and external layers which are
superior in resistance to deteriora-ted gasoline and low tem-
peratures.
The au-tomotive fuel pump is sometimes buil-t into
the fuel tank. In such a case, the fuel hose connected to the
fuel pump is re~uired to have oil-resistant internal and
external layers. Moreoverj the fuel hose is required to be
resistant to deteriorated gasoline and to low temperatures.
The deterioration of gasoline results from the high tempera-
ture in the engine room. The res:i~stance to low temperatures
has become necessary with the spread of automobiles into cold
districts. ~eretofore, there has been no rubber hose provided
Wit}l internal and external layers that meet these requirements.
According to the present invention there is provided
a rubber hose comprising an inner layer and an outer layer
which are made of vulcanizate of a rubber compound of partially
~0 hydrogenated unsaturated nitrile-conjugated diene copolymer
in which at least 50% of the conjugated diene units is hydro-
genated.
An oil-resistant rubber hose of this construction
has internal and external layers which are resistant to
deteriorated gasoline and low temperatures.
The rubber hose can also endure for a long period
of time when used as a fuel hose connected to a fuel pump
built into a fuel tank. In such use, both the internal layer
and external layer of the hose are exposed to gasoline.
The rubber hose can also endure for a long period
of time when used in extremely cold districts.
The rubber hose of this invention is superior not
only in detriorated gasoline but also in resistance to the
progaration of cracks. This performance is achieved by in-
corporating the rubber compound with polyvinyl chloride and/or
liquid NBR.
The invention will now be described in more detail,
by way oE example only, with reference to the accompanying
drawings, in which:-
Fig. 1 is a perspective view showing one embodiment
- 2
. ~. ~ 1.
5~
of the rubber hose of this invention.
DESC~IPTION OF THE PREFERRED EMBODIMENT
The internal layer 1 and the external layer 3 of
the rubber hose of this invention as shown in Fig. 1
are made of vulcanizate of partially hydrogenated
unsaturated nitrile copolymer rubber (referred to as
hydrogenated NBR hereinafter), or vulcanizate of a
polymer composition composed of hydrogenated NBR and/or
liquid NBR as mentioned below.
(a) Hydrogenated NBR
Hydrogenated NBR is an unsaturated nitrile-conju-
gated diene copolymer rubber produced in the usual way
by emulsion polymerization or solution polymerization,
.. ..
with at least 50~ of the conjugated diene units hydrog-
enated. If the degree of hydrogenation is less than
50~, the properties intended in this invention are not
obtained. 100~ hydrogenation is possible; but hydrog-
enation less than 98% is desirable for a proper cure
rate in the case of sulfur vulcanization~
The copolymer rubber to be hydrogenated is prepared
by copolymerizing an unsaturated nitrile such as acrylo-
nitrile and methacrylonitrile with at least one of con-
jugated dienes such as 1,3-butadiene, isoprene, and 1/3~
pen~adiene, or by copolymerizing the above-mentioned un-
saturated nitrile with a conjugated diene partly substi-
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tuted with methyl ester, butyl ester, and 2-ethylhexyl
ester of unsaturated carboxylic acid su~h as acrylic
acid, methacrylic acid, fumaric acid, and itaconic acid,
or with N-methylol acrylamide. Examples of such copoly-
mer rubbers include acrylonitrile-butadiene copolymer
rubber, acrylonitrile-isoprene copolymer rubber, acrylo~
nitrile-butadiene-isoprene copolymer rubber, acrylonit-
rile-butadiene-methyl acrylate terpolymer rubber, and
acrylonitrile-butadiene-b~tyl acrylate terpolymer rubber.
Most suitable among them is acrylonitrile-butadiene co-
polymer rubber. The quantity of the unsaturated nitrile
in the hydrogenated NBR is usually 10 to 70 wt%; and it
is properly determined according to the object of use
and the miscibility with PVC to be mixed 1n the polymer
compositions (b), (c), and (d) mentioned below.
(b) A polymer composition composed of the above-men-
tioned hydrogenated NBR (a) and polyvinyl chloride
resin (referred to as PVC hereinafter)
The PVC includes polyvinyl chloride and copoly-
mers of vinyl chloride and vinyl acetate or other mono-
olefinic monomers. The PVC is incorporated into the
hydrogenated ~R in an amoun-t greater than 5 wt%,
preferably about 20% (based on the total weight). If
the quantity is less than 5 wt%, the resulting hose is
not satisfactory in the resistance to deteriorated ~as-
57~
oline. The more the quantity of PVC incorporated, themore is enhanced the resin-attributable properties.
However, as a matter of course, there is a limit at
which the rubber composition can be vulcanized but the
resulting vulcanized rubber is poor in performance~
The quantiLy of PVC to be incorporated shvuld be deter-
mined according to the intended use and requirement.
The upper limit is usually 60 wt%. PVC is incorporated
into the hydrogenated NBR by using a roll or Banbury
mixer or by mixing in a solution, followed by coprecip-
itation and drying.
~c) A polymer composition composed of the hydrogenated
NBR (a) and a liquid unsaturated nitrile conjugated diene
copolymer having a number-average molecular weight of
500 to 10,000 ~referred to as liquid NBR hereinafter)
Any liquid NBR having a number-average molecular
weight less than 500 is easily extracted by solvents
from the polymer composition and does not provlde the
resistance to propagation of cracks. On the other hand,
any liquid NBR having a number-average molecular weight
greater than 10,000 does not improve the resistance to
propagation of cracks, either. A preferred value is
1,000 to 5,000~
For good miscibility with the hydrogenated NBR and
for the improved properties intended in this invention,
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the liquid NBR should be composed of 10 to 70 wt%, pref-
erably 20 to 50 wt~, of unsaturated nitrile; 20 to 80
wt%, preferably 25 to 75 wt~, of conjugated diene; and
0 to 20 wt~, preferably 0.1 to lS wt~, of vinyl monomer
which is copolymerizable with unsaturated nitrile and
conjugated diene. The unsaturated nitrile and conju-
gated diene are as mentioned under the paragraph for
hydrogenated NBR. A preferable unsaturated nitrile is
acrylonitrile, and a preferable conjugated diene is
butadiene or isoprene. The vinyl monomer copolymeriz-
able with the unsaturated nitrile and conjugated diene
includes, for example, unsaturated carboxylic acidfi
such as acrylic acid, methacrylic acid, and itaconic
acid/ and esters thereof; vinyl pyridine nomer such
as 2-vinylpyridine; and N-methylol acrylamide. Pref-
erable among them are acrylic acid and methacrylic acid.
The liquid NBR is incorporated into the hydrogenated
NBR in an amount greater than 2 wt% (based on the total
weight). If the quantity is less than 2 wt%, the effect
of the liquld NBR is not sufficient. The upper limit is
about 50 wt~ (based on the total weight), at which the
resulting polymer composition is excessively low in vis~
cosity and is poor in physical properties such as perma-
nent compression set. The liquid NBR can be incorporated
into the hydrogenated NBR in the same way as mentioned
i7~
in the above paragraph (b).
Id) A polymer composition composed of the polymer co~-
position (c) [which is composed of the hydrogenated N~R
and the liquid NBR3 and PVC
The PVC and the quantity and method of its incor- :
poration are as mentioned in the above paragraph ~b).
That is to say, the PVC includes polyvinyl chloride and
copolymers of vinyl chloride and vinyl acetate or other
monoolefinic monomers. The PVC is lncorporated into
the pnlymer composition of hydrogenated NBR and liquid
NBR in an amount greater than 5 wt%, preferably about
20 wt% (based on the total weight)~
The above-mentioned hydrogenated NBR (a) and the
polymer compositions 5b), (c), and (d) composed mainly
of hydrogenated NBR may be incorporated with commonly
used auxiliary materials including inorganic fillers
such as carbon black, silica, and metal oxide; organic
~illers such as lignin; softener, plasticizer; and col-
orant; together with a proper amount of sulfur or per-
oxide vulcanizing agent and vulcanization accelerator.
The rubber hose of this invention is produced by
the steps of forming the inner layer 1 by extruding
the above-mentioned polymer ccmposition, forming the
braided reinforcement layer 2, applying an adhesive,
forming the external layer 3 by extruding the above-
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mentioned polymer ccmposition, and finally vulcanizingthe green hose.
The present invention has been described with
reference to a three-layered rubber hose made up of
an inner layer 1, a braided reinforcement layer 2, and
an outer layer 3. However, this invention is not
limited to it. The scope of this invention covers
multi-layered rubber hose having an intermediate layer
in addition to thin inner and outer layers.
