Note: Descriptions are shown in the official language in which they were submitted.
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IMPROVEMENTS IN OR RELATING TO HOSE
This invention concerns improvements in or relating
to hose and in particular, though not exclusively, to
layflat hose suitable for transporting a wide range of
fluids.
Layflat ho~e for certain applications may comprise
a fluid imperviou~ inner layer chemically and physically
inert to the fluid to be transported, a textile reinforce-
ment layer to provide the required burst strength and an
outer cover to protect the reinforcament layer from damage
cau3ed by abrasion during handling.
Conventionally tho liner has been made from a
rubber ba~ed material and th- hose is made by extruding
the liner, inserting the unvulcani3ed liner into a textile
rein~orcement jacket onto whlch the outer cover has
previously beon extruded and subseguently inflating the
a~embly with steam under pre~ure to vulcanise the liner
and effect bonding of the liner to the reinforcement jacket.
Th-re ha~ be-n a trend away from conventional
vulcani~able rubber-based materlals towards thermoplastic
ela~tomers for the liner, thermoplastic elastomers being
both lighter than and chemicall.y and physical.l.y.in~rt towards
a wider..range o.f fluids .than..the. conventional.vulcanisable
rubber-based materials thus.enabli~g a given hose constructlon
to have a much..w.ide~ r.ange of appll,ca.tion9 ~
Howe.ver this..change ha~ resulted.in a.problem in
obtaining a suffic.i.ently ~trong bond between the thermo-
plastic elastomer of the liner and the textile.reinforcement
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layer which is maintained both under the operating
con~itions and in the event of fluid leakage through the
liner. This adhesion problem is due to the lack of polar
chemical groupings in the known thermoplastic polyetherester
elastomers used for the liner and is greatest when the
textile reinforcement layer ~ made of polyester or poly-
amide material. As a result it has been necessary to use
an adhesive to bond the known;thermoplastics liners to the
reinforcement layer. To date;j~adhesives applied from solvent
based solutions or pastes containing at least 3~/0 of solvents
such as chlorinated hydrocarbons, generally using two
component sy~tems followed by evapor~ation of the solvent,
have been u~ed and it ha~ been found that the residual tack
and frictional characteristic~ of the resultant adhesive
coated liner effectively restricts the length of liner
which can be insorted into the textile jacket without
stretching or distorting the liner to,about 200 feet.
Furthermore, as a result of leakago through either the
liner or cover, it has been found that the adhe~ive bond
betwoen tho liner and reinorcement layor is rapidly
weakened by contact with certain fluids e,g. hydro-carbon
uels, leading to hose delamination and consequently the
ho~es aro un~uitable for transporting such fluid~.
It i~ an object of the presont invention to
provide a hose having a thermoplastics liner which reduce~
at least some of the above-described disadvantages and can
be used to transport a wide range of fluids including
hydrocarbon fuels~
8~S
According to the present invention we provide a
method of making a hose having a continuous unspliced length
of greater than 250 feet comprising an inner liner of a
thermoplastic elastomer, a textile reinforcement layer and an
outer cover of a thermoplastic elastomer in which said liner
is bonded to said reinforcement layer by a hot melt polyester
adhesive, comprising the steps of forming said reinforcement
layer, applying said outer cover thereto, forming said liner
and applying a hot melt polyester adhesive to the external
surface thereof, said adhesive having a melting point below
that of said liner material, inserting said adhesive coated
liner through said reinforcement layer, passing a fluid
medium into said liner to inflate the assembly so formed,
applying heat to said assembly sufficient to activate said
adhesive and effect bonding of said liner to said reinforcement
layer.
Preferably the polyetherester elastomer of the
inner liner has the following characteristics:
mpt : 156-210C, preferably 164-200C
(ASTM D 2117)
Hardness : 35-45D, preferably 37-43D
(ASTM D 2240)
Melt Index 190C
2160G g/10 min : 2-8, preferably 4-6.5
(ASTM D 1238E)
Tensile Strength : 15-30 MNm min preferabl~ 19-26
(ASTM D 638) MNm min
Elongation at Break : 400~ minimum
Suitable elastomers are those sold under the
Registered Trade Marks of Hytrel (ex Du Pont) and Arnitel
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(ex AKZO).
The melting point of the polyester adhesive should
be such that the integrity of the hose remains substantially
unaffected by the temperatures to which the hose is
generally subjected under normal operating conditions. At
the same time the melting point should be sufficiently
below that of the liner material, preferably at least 20~C--
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below that of the liner material, 90 that during manufacture
of the hose an increase in temperature to activ~te the
adhesive and effect bonding of the liner to the textile
reinforcement does not cause appreciable softening of the
liner which could result in undesirable changes in the liner
thickness.
An adhesive which meets the abovelcriteria and is
suitable for use with a liner material having the above-
mentioned preferred characteristics has a melting point of
not less than 100C more preferably not less than 130C.
An example of a suitable adhe~ive is that sold under the
~egistered Trade Mark Grilesta 6506 (ex Grilon) which has
a melting point in the range 100 - 140C more preferably
130 - 140C and a viscosity of 6500 poise at 160C and
2160 gram load (DIN 53735).
The jacket may be of any known construction, for
example knitted braided or woven to produce a balanced
con~truction having the required strength characteristics
for a given application. Alternatively the ~acket may be
of non-woven construction e.g. a spiral winding. Preferably
the jacket is of woven construction comprising one or more
layers made from natural or synthetic textile material, for
example cotton, polyester, polyamide or polyvinyl acetate.
A suitable aromatic polyamide i~ that sold under the
Registered Trade Mark Kevlar (ex Du Pont).
Preferably the warp and weft yarns of the jacket
are pretreated with a heat reactivatable resin during
production to improve the adhesion of the hot melt polyester
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adhesive. Suitable yarns are those sold under the
Registered Trade Mark Diolen 164S. (ex British Enkalon).
The polyurethane elastomer of the cover may be
selected from the group consi~ting of polyester, polyether,
polyester caprolactone and polyesterether type. Polyester
caprolactones are preferred as these exhibit good resistance
not only to abrasion and cutting caused by handling but also
to a wide range of fluids including hydrocarbon fuel~.
Preferred polyurethanos are those which are free from low
molecular weight oligomers and from waxes, lubricants and
other low molecular weight processing aids. Suitable
polyester caprolactones are those sold under the Registered
Trade Marks Caprolan (ex Elastogram) and Rowathane 1080
(ex Rowa GmbH).
In addition to the improved chemical and physical
re~istance to a wide range of fluids including hydrocarbon
fuels, ho~es according to the present invention having a
th-rmoplastics linor can bo made in continuous unspliced
lengths greatort~an 250 foet by conventional methods, for
example lengths greater than 500 feet can be made.
The invention will now bo doscribed in more detail
by way of examplo only with reforence to the accompanying
~chematic drawing which show~ in cro~s-~ection a hwe
according to the presont invention.
The hose shown in the accompanying drawing
comprise~ a polyethere~ter (Hytrel) liner 1 bond~d to a
polyester (Diolen 164S) jacket 2 by a hot melt polyester
adhesive 4 (Grilesta 6506) and an outer polyurethane Caprolan
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cover 3
The liner 1 i9 made by hot melt extrusion of the
polyetherester and is subsequently coated with the adhesive
4 by cross head or slot die extru~ion
The jacket 2 of circular woven construction is formed
separately and subsequently coated on a mandrel with the
polyurethane cover 3 by cross-head extrusion, Extrusion of
the cover material i9 such that sufficient penetration into
tho textile jacket 2 occurs to allow some ~irect adhesion
between the adhesive 4 applied to the liner 1 and the cover
matorial, thereby helping to prevent delamination
The mandrel i9 then removed from the polyurethane
covered jacket 2 and the adhesive coated liner 1 i9 drawn
through the ~acket by any conv-ntional technique
The hose assombly is then inflated with alr to a
pressure above atmospheric to position the liner 1 within
the jacket 2 and then the air is replaced by steam at 40 psi
at a temporature of 140C for 5-10 minutes to actlvate tho
adhesive and effect bonding of the liner to tho jack-t
Blistering of the liner by any gases or vapour trapped
between the liner and cover can be prevented by replacing
the steam with air at pressure above atmosph-ric pressuro
and allowing the bonded hose to cool whilst still inflatod
~ Blistering o~ the cover 4 can be prevented by pin-holing
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the cover during extrusion of the`cover material onto the
jacket 2
Alternatively blistering may be prevented by
thoroughly drying the hose assembly at a temperature below
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the activation temperature ofthe adhesive e.g. by passinq
air through the space between the liner and cover whilst
heating the assembly, for example, by steam passing through
the liner.
The hose according to the present invention, which
can be made in continuous unspliced lengths greater than
500 feet exhibits good chemical and physical resistance to
a wide range of fluids both when transporting and when
exposed to the fluids. The hose may be installed as a
pormanent supply lino or may be used to effect a temporary
repair to a damaged supply line or simply to transport
fluid from a fixod outlot to a delivery point. The range
of fluids which can be transported by the hose include
hydrocarbon fuols, o.g. potrol, chemical ~olvents, organic
fluid~ and drinking wator.
