Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROU~D OF THE I~ TION
In the past, hoses for high pressure fluid service have
been made of various plastic materials and construction. For
example, U.S. Patent No. 3,062,241 discloses a hose having a
nylon core tube, a dacron braided reinforcement, and a nylon
sheath. U.S. Patent No. 3,334,165 discloses a hose having a
nylon core, a nylon reinforcement, and a nylon sheath bonded to
the reinforce~ent. A hose having a olyurethane core and sheath
poly ~tl~le~3 e 7'er e, p~ t~
, with a reinforcement of nylon, ddcron` or rayon is disclosed in
U.S. Patent 3,116,760. In general, the particular plastics used
for the core tube and sheath in these and other prior art hose
constructions have not been completely satisfactory. For example,
hoses with nylon core~ and/or sheaths have limited flexibility
and/or limited temperature resistance, while hoses with poly-
urethane cores and/or sheaths, although relatively flexible, have
limited temperature resistance.
Fiber reinforced resin tubular articles such as pipe
have been described in U.S. Patent 3,156,598. An example of a
resin utilized in this patent is a thermosetting polyester resin
in which at lea~t one of the reactants contains an unsaturated
double bond. Other thermosetting resins also are disclosed.
SUMMARY OF THE INVENTION
The present invention provides a high pressure hose
having a core tube of extruded chemically extended polyester
having a hardness of at least about 90A durometer and a rein-
forcement of fibrous strands in tensioned contact with said core. ~ '
In a preferred embodiment, the hose comprises the core tube of
extruded chemically extended polyester, a sheath of a synthetic -
plastic, and a tensioned reinforcement of fibrous strands
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interposed between the sheath and the core. The hose of this
invention has greater flexibility and higher temperature
resistance than hoses previously known, such as those having a
nylon core, and has higher temperature resistance than the more
flexible polyurethane-based constructions.
DESCRIPTIO~
Figure l illustrates a side elevation, partly broken
away in successive structural layers, of a length of a hose made
in accordance with this invention;
Figure 2 is a side elevation, partly broken away in
successive structural layers, of a length of another example of
the hose made in accordance with this invention;
Figure 3 is a side elevation, partly broken away in
; successive structural layers, of a length of another example of
a hose of this invention; and
Figure 4 schematically illustrates a method of con-
structing the hose.
The hose constructions of this invention are illustrated
in the drawings. In Figure 1, the hose lO comprises a core tube
11 and a reinforcement 12. Core tube 11 is prepared from a
chemically extended polyester material, and the core tube is
made by extrusion of the polyester. Various extrudable chemically
extended polyester may be utilized in the formation of the core
material. Examples of such chemically extended polyesters which
can be utilized are described in, for example, U.S. Patents
3,651,014; 3,766,146 and 3,763,109. The copolyester elastomers -
described in these patents are contemplated as being useful in
the preparation of the core materials of this invention.
one example of a chemically extended polyester material
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which can be utilized in the formation of core tube 11 is made of
a chemically extended polyester material such as those available
from the E.I. DuPont de Nemours Company under the general
designation ECD, and in particular, the designation ECD-2683, 2968, ~-
and 2682. It is preferred that the extruded chemically extended
polyester have a hardness of at least 90A durometer and within `
the range of from about 90A durometer to about 65D durometer.
The polyester material available from DuPont under the designation
ECD-2683 has a durometer of about 55 on the D scale, is of a
high molecular weight, is nonreactive with a specific gravity of
about 1.20 g/cc, a bulk density of about 0.66 g/cc and a tensile
strength of about 1825 psi at 302F. DuPont's polyester ECD 2968
has a higher molecular weight with a durometer of about 63D
whereas DuPont's ECD 2780 polyester having a durometer of 90A
; may be utilized where greater flexibility is desired.
Another example of a chemically extended polyester is
a commercial polyester available from DuPont under the trade
designation ECD-2682 which i8 capable of resisting hydraulic oil ~,
at 250F., continuous use, as compared with 200F. maximum
temperature resistance under continuous use for previously known
nylon materials. This polyester has no plasticizer and, therefore,
retains its flexibility over extended periods of time. That is,
it does not become brittle through loss of the plasticizer over
extended periods of time at temperatures as low as -65F. On
the other hand, the flexibility of nylons is seriously impaired
at temperatures below -40F. ;
The tensioned reinforcement of fibrous strands, 12,
which are in tensioned contact with core tube 11 may be braided,
knitted, woven, or even matted strands. Knitted reinforcements
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which may be useful in ~he present invention may comprise an
ordinary knit stitch, and it is preferred to provide the knitted
~- reinforcement in such a manner that the axis of the reinforcement
layer is at an angle to the axis of the core tube. Similar
arrangements of braided or woven fabrics can be utilized.
~he fibrous strands which are utilized in the formation
of the reinforcement may comprise any suitable fiber material
such as glass, metal, textile fibers, synthetic fibers, polymeric
materials, etc. More specifically, fibers made from polyamides
such as polyhexamethylene adipamide, and other nylon-type
materials, polyesters such as polyethylene terepthalate (d~r~n~,
...... ... polyolefins such as polyethylene and polypropylene, polyvinyl
chloride, polyacrylonitrile, polystyrene, polyvinylidene halides
such as polyvinylidene chloride. In general, the traits of fiber ;
to be used for the reinforcement will depend upon the end u e
to which the hose is to be put. For example, glass fibers are
commercially available with a variety of coatings such as epoxy
coatings. The coating should impart good adhesion properties
and good moisture resistance properties to the fiber.
Reinforcement 12 is preferably nylon fibrous strands
that are either spirally wrapped upon the core or formed into a
braid. In either case, the reinforcement is in tension upon the
core tube and is closely wound or braided so as to provide sub-
stantially 100% coverage over the core tube. The nylon rein-
forcement resists temperatures up to about 250F., continuous use,
and is, therefore, ideally matched with the chemically extended
polyesters such as ECD-2682.
In instances where the hose is to be used for higher
hydraulic pressures, a second layer of reinforcement may be
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applied over the first reinforcement layer. In such instances, -
it is preferred to use two knitted or braided layers wherein one
layer comprises a "left-hand stitch or braid" and the other
comprises a "right-handed stitch or braid" in such a manner that
the twisting tendency of each layer counteracts the twisting
tendency of the other.
Figure 2 illustrates another embodiment of the invention
wherein the hose comprises a core tube 11, an outer sheath 13,
and a tensioned reinforcement layer 12. Sheath 13 may be made of
any of the known synthetic plastics which have been useful in
the formation of hose structures. Examples of such plastic
materials include the chemically extended polyesters described
above which are useful as the core material, as well as other -
synthetic plastics such as polyamides (polyhexamethylene adipamide)
and other nylon-type materials, polyesters such as polyethylene
terepthalate, polyolefins such as polyethylene and polypropylene, ;`
polyvinyl chloride, polyacrylonitrile, polystyrene, polyvinylidene
halides such as polyvinylidene chloride, polyurethanes, rubbers, ~ `
and the chemically extended polyesters which are also useful as
the core material. The selection of the particular synthetic
plastic useful as the sheath material will depend upon the
particular end use of the hose and the properties desired of
the sheath. For example, where it is necessary that the sheath
be able to withstand high temperatures, the chemically extended
polyester such as DuPont's ECD-2682 material will be particularly
useful. On the other hand, where the tube of the invention is to
be utilized in hydraulic applications, other materials can be
utilized for the formation of the sheath which is not exposed to
such high temperatures as is the core tube.
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Figure 3 illustrates a more detailed hose construction
comprising core tube 11 prepared of the materials described above,
tensioned reinforced layer 12, and sheath 13 comprised of
materials as described above. In the particular embodiment
illustrated in Figure 3, the reinforcement is bonded to the core
tube by an adhesive layer 14, and the sheath 13 is bonded to the
reinforcement 12 by adhesive 15. The adhesives identified as
14 and 15 may be the same or different adhesives, but in general,
the adhesive should be an effective bonding agent for each of
the materials with which it comes in contact. Any of the
commercially available adhesives which are effective to form
such a bond may be utilized in the invention. The nature of the
adhesive is not critical. Examples of adhesive which are useful
include the urethane adhesive~, epoxy adhesives, etc. An example
of a urethane adhesive is a polyester isocyanate adhesive such as
available from the Daubert Chemical Company under the designation
Daubond 8412A and Daubond 8412B. m ere are many epoxy adhesives
available commercially, and one example of such an adhesive is
Epon 872-X75 resin available from the Shell Chemical Company
which is cured with a suitable amine or modified polyamine.
As can be seen from the examples qiven above and in
particular Figures 1 and 2, it is not imperative that the various
layers which comprise the hose be bonded one to another.
Satisfactory hose constructions can be prepared in the absence
of any bonding between the various layers. Moreover, where
bonding between various layers is desired, it is not necessary to
utilize adhesives since bonding can be effected by other known
techniques such as by heating one or; more of the various layers
which comprise the hose which results in a melting of one or
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more of the layers, which melting results in the formation of a
bond upon cooling, or one or more of the layers may be treated
with a solvent which effects a softening of said layer and
results in the formation of a bond between the layers. Such
techniques are well known in the art. In some instances, hose
constructions such as illustrated in Figure 2 will be prepared
where the reinforcing layer is bonded to the core tube but is
not bonded to the sheath. Conversely, the sheath 13 may be - -
bonded to reinforcing layer 12 without any bond between core
tube 11 and reinforcing layer 12.
A hose can be prepared in accordance with this
invention by the procedure shown schematically in Figure 4.
In this example, the hose is constructed by passing core tube 11
from a storage reel 20 through a tank 21 containing a liquid ;
adhesive such as Daubond 8412A passed a serving mechanism 22
that applies reinforcement 12 in either a spiral wrap or braid
form to the core tube. The latter then passes into tank 23
containing an adhesive which may be the same as contained in
tank 21 or a different adhesive such as an epoxy adhesive, into
a crosshead 24 through which sheath 13 is extruded over the
adhesive, and through a water bath tank 25 for cooling before ~ -
being stored on reel 26.
The hoses described above, and particularly with respect
to Figures 1-4, are useful for hydraulic and other high pressure
fluids. These hoses exhibit greater flexibility and higher
temperature resistance.
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