Note: Descriptions are shown in the official language in which they were submitted.
2~
FLEXIE~LE ~OSE
HAVING MOISTURE BARRIER
INTRODUCTION
Thi~ inventi¢n relates generally to a flexible
reinforced hose for use in the conve~ance of fluids and
more particularl~ to a flexible reinforced hose having a
composite core tub~ that is adapted to provide a barrier
to the penetration of moisture into the ~luid.
BA~KGROUND OF THE INVENTION
Flexible reinforced hose has been used for many
years to convey a variety of fluids from on~ point to
another. In some instances the fluid belng conveyed
throu~h the hose is of a typ~ that would be adversely
affected in the event that it wa~ exposed to moisture
such as water vapor duri~ s presence in the hose.
Unfortunately, excep~ing for certain costly and
difficult to proeess fluorinated polymers, the type of
materials commonly used to make hoses such as natural
and syn~hetic rubber, nylon, polyester and polyu~e~hane
materials have characteristically possessed poor
resistance to penetration by moisture. Additional
components, such as costly metal tapes or metal-plastic
laminates, have been required to be disposed about the
core tube to prevent moisture from penetrating through
the core tube and contaminating the fluid being conveyed
through the hose~
Some hose construs~tions have become more
sophisticated by the use o core tubes having multiple
l~yers rather than a single layer as was common practice
in the past. An examp.l.e of a multiple layered core tube
in a hose construction can be found in United Sta~es
Patent 2,564,602 in which l:he core tube has an inner
layer made from a relatively so~t rubber and an outer
layer made from a harder poJ.ymeric material such as
nylon, polyamide chloride or polyethy~ene for protecting
the inner rubber layer from damage by metal braid
reinorcement disposed about the core tube. An example
of a coextruded tube of polyurethane and polyvinyl
chloride can be found in United States Patent 3,411,981
which featur~s a polyurethane layer melt fused to either
or both the inner and outer surface of the polyvinyl
chloride layer to improve the streng~h of the polyvinyl
chloride layer~ An example of a composite tube having
multiple layers is found in United States Paten~
3,561,493 in which two or more adjacent layers of
different materials are bonded together by an
intermediate layer made up of a mixture of the materials
from which the layers desired to be bonded toyether are
made.
Although polyolefin polymers such as
polyethylene are considerably lower in cost than
fluorocarbonated polymers and are known to provide a
good barri~r against moisture penetration~ their use as
a core tube in hose constructions ha~ heretofor been
limited due to their greater inherent stiffness compared
3b to more conventional hose materials and ~o their
~Z~5~t
tendency to kink in tube form. Additionally, it has not
been satisfactorily demons~r.ated that polyolefin
polymers in tube form can be suitably bonded to
en~ompassing reinforcement material which bonding wvuld
reduc~ their tendency to kink. Polymer compositions
commonly used in hose constructions such as plasticized
nylon, neoprene and NBR cont:ain additives to improve
~lexibility, processi~ and other properties which over
a period of time are abl~ to migrate into and
contaminate the ~luid being conveyed th~ough the hose.
Polyolefins such as...polyethylene do not require such
additives and are frequently used in food and drug
applications where contamination is of concern.
None of ~he prior-art hose, whether having a
composite core ~ube or no~, have heretofor add~essed the
problem 3~ preventing moisture from penetrating through
the core tube and co~tamina~ing the fluid without
encountering the problem of flexibility and bonding
associated with polyolefin materials or the high cost of
fluoroc~rbonated polymers or tapes such as metal-plastic
laminate tapes which are often difficult to apply in
addition to characteristically lessening ~he flexibility
of th~ hose as well as having seams which, if not
sealed, provide an entrance-way for moisture through the
25 . core tube and into the fluid bein~ conveyed through the
hose.
SU~lARY OF THE INVENTION
Accordingly, it is an object of this invention
to provide a flexible reinforced hose that is able to
prevent moisture from contaminating or otherwise
affecting fluid being conveyed through the hose by means
of a moisture barrier tha~ is easily and economically
incorporated as a part of the hose core tube during the
manllfacturing process.
It is another object of this invention to
provide a flexibl~ reinforced hose that is provided with
a moisture barrier as an inner layer o~ the hvse core
tube as a means o~ preventing moisture from
contaminating or otherwise affecting fluid being
conveyed through the hose, that is economical to apply,
and that, in conjunction with another outer layer of the
core tube, does not adversely affect the flexibility of
the hose~
It is a fur~.her object of this invention to
provide a flexible reinforced hose which will not
significantly contamina~e the fluid being conveyed.
.
I~ is yet another object of thi~ invention to
provide a flexible reinforced hose that is able to
incorporate a layer of polyethylene as part of the core
tube of the hose as a barrier against penetration of
moisture into fluid being conveyed by the hose while
maintaining a high level of flexibility in the hose in
addition to enabling the core tube to be bonded to the
hose reinforcement material.
~ 5 --
BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a partially broken away .side
elevation of an embodiment of the hose of the invention;
and
FIGURE 2 is a parl-.ially broken away side
elevation of anothex embod:iment of the hose of the
invention.
DETAILED DESCRIPTION OF PREFERR~D EMBODIMENTS
FIGURE 1 shows an embodiment of the invention
in the form of hose 11~ Hose 11 has a composite core
tube 1 comprised of an inner annular shaped layer 2
surrounded by outer annular shaped layer 3. A layer of
reinforcement material 4 is disposed abou.t core tube 1
and an outer annular shaped protection jacket 5 is
disposPd about reinforcement layer 4.
Rei~forcement material 4 may be any
reinforcement material that ls able to provide the
strength and other properties desired for hose 11.
Reinforcement material 4 may be in the form of metal
wire or it may be in the form of synthetic fibers made
rom aliphatic or aromatic nylon, polyethylene
terephathalate ester or the like or combinations
thereof. Althouyh shown in the form of a braid in
FIGU~E 1, it is to be understood that any suitable
manner of disposing one or more layers of reinforcement
about core tube 1 such as the oppositely helically wound
strands shown in FIGURE 2 is considered to be within the
scope of the invention.
Inner layer 2 of core tube 1 is made from a
~hermoplastic polyethylene and outer layer 2 of co~e
tube 1 is made from a thermoplastic rubber. Pre~erably
the polyethylene material forming layer 2 is a linear
polyethylene in which paral:Lelism between adjacent
carbon chains is highly controlled as is commonly known
to those ordinarily skilled in the art.
Variations available in the selection of the
density o the particular polyethylene to make inner
laye~ 2 can be used to advantage ~or tailoring the hose
for a particular application. Generally polyethylene is
characterised as having low, intermediate and high
density. Typically low density polyethylene has a
d~nsity of from about .9lS to about .930 gm/cc;
intermediate density polyethylene has a density of from
about .930 to about .945 gm/cc and high density
polyethylene has a density of from about .945 to about
.965 ym/cc. Generally the stiffne~s of a polyethylene
increases as the de~sity increases due to what is
believed to be closer packing of the carbon chains as
th~ density increases. Thus one may sele~t a low
density polyethylene where it is desired to impart
greater flexibility to the hose or an intermediate or
high density polyethylene where it is desired to
decrease the flexibility such as in the case of sewer
hose when the hose is pushed through sewers and m~y tend
to fold or buckle in the event the hose is too
flexibleO An example of a linear low density
-- 7
polyethyl~ne found to be o~ advantage ~or making layer 2
is sold by Union Carbide Corporation under ~he trade
numbers GRSN 7-441. Polyethylene, particularly linear
polyethylerle, when used ~o make inner layer 2 has been
found to provide an excel~ent barrier again~t moisture
penetration through core tube 1 into the fluid heing
conveyed by the hose oE the invention as well as haviny
the density range selectivity ability previously
de sc r i bed ~
Outer layer 3 o~ core tube 1 is made f rom a
thermoplastic rubber. An example of a thermoplastic
rubber found to be of advantage for making the core tube
of the hose of the invention is sold as trade number
2103 under the trademark "Kraton" by Shell Chemical
Company. Kraton 2103 is believed to be a
styrene-butadiene-styrene block copolymer.
Although polyethylene has been notoriously
difficult to bond to, it has been suprisingly found that
when ou~er layer 3 of a thermoplastic rubber such as
Kraton 2103 is coextruded in heated form in conjunction
with inner layer 2 of polyethylene, the two mel~ fuse
together to form a strong bond that is of advantage in
the performance of ~he hose~
The flexibility of core tube l is not only
2S controllable by the selection of the density of inner
polyethylene layer 2 but also by the relative thickness
of layer :2 with respect to layer 3. Thermoplas~ic
rubber i5 considerably more flexible than polyethylene
-- 8 --
and thus the greater the thickness of layer 3 relative
to layer 2 the greater the flexibility and vice versa.
The bore throuyh core tube 1 of the hose made in
accordance with the invention typically have an inner
hose diameter of about 3/16 inch to about l.5 inches. A
particular construction ound to combine attractive
flexibility in combination with providiny a highly
effeckive barrier to the penetration of moisture into
the fluid being conveyed by the hose is where (for an
inner hose diameter of approximately one inoh) the inner
polyethylene layer 2 has a thickness of about .065 inch
and the outer layer thermoplastic rubber layer 3 has a
thickness of about ~007 inch.
FIGURE ~ show~ an embodiment of the invention
in the form of hose 12. Hose 12 has a composite core
tube 1 having an inner polyethylene layer 2 and an outer
thermoplastic rubber layer 3 previously described with
respect to hose 11 of FIGURE 1. Coxe tube 1 has
oppositely helically wound reinforcament layers 7 and 8
20 disposed about core tube 1 as shown in FIGURE 2. An
adhesive layer 6 is disposed between the outer surface
of layer 3 and reinforcement layer 7 and bonds them
together. An adhesive layer 9 is disposed between and
bonds reinforc@ment layers 7 and 8 togPther and an
adhesive layer 10 is disposed between and bonds
reinforcement layer 8 to protective jacket 5.
Elose 12 is illustrative of the fact that more
than one reinforcement layer made from materials or
combinations of materials previously described may be
used depending upon the nature of the particular hose of
the invention being constructed and that one or more o
such layers of reinforcemell may be bonded together by a
suitabLe adhegive when such iS desired. Hose 12 is al50
S illustrative of the fact that protective ja~ket 5 may be
bonded to the outerm~st layer of reinforcement of the
hose of the invention where such is desired.
It is to be noted that the composite core tube
of the hose of the invention may itself be used as a
tube devoid of any reinforcement layers where the
particular application for which the tube is to be used
does not require the strength provided by the
reinforcement layers.
Although in some applications an outer
protective jacket may not be required over the outermost
reinforcement layer of the hose of the invention, in
mos~ cases it is preferred to use an outer protective
jacket such as jacket 5 to protect the rein~orcement
f rom dama~e. Jacket 5 may be made from any suitable
material or wrapping that impar~s the degree of
protec~ion desired. Commonly protective jacket 5 i5
made from rubber, nylon or polyurethane material
having the flexibility, strength and abrasion resistance
desired for a particular application.
One of the advantages found in providing a
thermoplastic rubber outer layer 3 about inner
polyethylene layer 2 is that whereas it would have been
extremely difficult to bond reinforcement layer 7 to
- 10 -
poyethylene layer 3, layer 7 can be bonded to
thermoplastic rubber layer 3 in a relatively simple
manner by mean~ of a suitable adhesive such a~ formed by
solvating an amount of the thermopLastic rubber in a
suitabLe solvent to form a cement or by making an
adhe~ive i.n situ by ~olvating the surface o~ layer 3 by
means of a suitably selected solvent so that the strands
of reinforcement material become embedded in the outer
surface of layer 3 due to the softening of the outer
surface o layer 3 caused by the solvent. Although
other solvents may also be suitable, it has been found
that either ~richloro ethylene or methylene chloride is
an ef~ective solvent when layer 3 is made from a
styrene-butadiene-styrene block copolymer compound such
as Kraton 2103 sold by Shell Chemical Company.
Providing a composite core tube in the hose of
the invention having an inner layer in the form of a
polyethylene material and an outer layer in the form of
a thermoplastic rubber provide~ a simple and economical
way of providing a barrier against penetration of
moisture into the fluid being conveyed through the hose
by means of the polyethylene layer while imparting an
~ttractive flexibility to tha hose by means of the
thermoplastic rubber layer in addition to the suprisin~
2S advantage that the polyethylene and thermoplastic rubber
layers are abLe to be melt fused together to provida
greater integrity to the core tube as well as enabling
the rein~orcement material closest to the core tube to
be bonded thereto in a much simpler manner than would
have been the case had the outer layer been made from
the polyethylene material.
