Field of the Invention
[0001] The present invention relates to a flexible fluid containment vessel (sometimes hereinafter
referred to as "FFCV") for transporting and containing a large volume of fluid, particularly
fluid having a density less than that of salt water, more particularly, fresh water,
and a method of making the same. Such a vessel is known from GB-A-933089.
Background of the Invention
[0002] The use of flexible containers for the containment and transportation of cargo, particularly
fluid or liquid cargo, is known. It is well known to use containers to transport fluids
in water, particularly, salt water.
[0003] If the cargo is fluid or a fluidized solid that has a density less than salt water,
there is no need to use rigid bulk barges, tankers or containment vessels. Rather,
flexible containment vessels may be used and towed or pushed from one location to
another. Such flexible vessels have obvious advantages over rigid vessels. Moreover,
flexible vessels, if constructed appropriately, allow themselves to be rolled up or
folded after the cargo has been removed and stored for a return trip.
[0004] Throughout the world there are many areas which are in critical need of fresh water.
Fresh water is such a commodity that harvesting of the ice cap and icebergs is rapidly
emerging as a large business. However, wherever the fresh water is obtained, economical
transportation thereof to the intended destination is a concern.
[0005] For example, currently an icecap harvester intends to use tankers having 150,000
ton capacity to transport fresh water. Obviously, this involves, not only the cost
in using such a transport vehicle, but the added expense of its return trip, unloaded,
to pick up fresh cargo. Flexible container vessels, when emptied can be collapsed
and stored on, for example, the tugboat that pulled it to the unloading point, reducing
the expense in this regard.
[0006] Even with such an advantage, economy dictates that the volume being transported in
the flexible container vessel be sufficient to overcome the expense of transportation.
Accordingly, larger and larger flexible containers are being developed. However, technical
problems with regard to such containers persist even though developments over the
years have occurred. In this regard, improvements in flexible containment vessels
or barges have been taught in U.S. Patents 2,997,973; 2,998,973; 3,001,501; 3,056,373;
and 3,167,103. The intended uses for flexible containment vessels is usually for transporting
or storing liquids or fluidisable solids which have a specific gravity less than that
of salt water.
[0007] The density of salt water as compared to the density of the liquid or fluidisable
solids reflects the fact that the cargo provides buoyancy for the flexible transport
bag when a partially or completely filled bag is placed and towed in salt water. This
buoyancy of the cargo provides flotation for the container and facilitates the shipment
of the cargo from one seaport to another.
[0008] In U.S. Patent 2,997,973, there is disclosed a vessel comprising a closed tube of
flexible material, such as a natural or synthetic rubber impregnated fabric, which
has a streamlined nose adapted to be connected to towing means, and one or more pipes
communicating with the interior of the vessel such as to permit filling and emptying
of the vessel. The buoyancy is supplied by the liquid contents of the vessel and its
shape depends on the degree to which it is filled. This patent goes on to suggest
that the flexible transport bag can be made from a single fabric woven as a tube.
It does not teach, however, how this would be accomplished with a tube of such magnitude.
Apparently, such a structure would deal with the problem of seams. Seams are commonly
found in commercial flexible transport bags, since the bags are typically made in
a patch work manner with stitching or other means of connecting the patches of water
proof material together. See e.g. U.S. Patent 3,779,196. Seams are, however, known
to be a source of bag failure when the bag is repeatedly subjected to high loads.
Seam failure can obviously be avoided in a seamless structure. However, a seamed structure
is an alternative to a simple woven fabric as it would have different advantages thereto,
particularly in the fabrication thereof.
[0009] In this regard, U.S. Patent No. 5,360,656 entitled "Press Felt and Method of Manufacture",
which issued November 1, 1994 and is commonly assigned, the disclosure of which is
incorporated by reference herein, discloses a base fabric of a press felt that is
fabricated from spirally wound fabric strips.
[0010] The length of fabric will be determined by the length of each spiral turn of the
fabric strip of yarn material and its width determined by the number of spiral turns.
[0011] An edge joint can be achieved, e.g. by sewing, melting, and welding (for instance,
ultrasonic welding as set forth in U.S. Patent No. 5,713,399 entitled "Ultrasonic
Seaming of Abutting Strips for Paper Machine Clothing" which issued February 3, 1998
and is commonly assigned, the disclosure of which is incorporated herein by reference)
of non-woven material or of non-woven material with melting fibers.
[0012] While that patent relates to creating a base fabric for a press felt such technology
may have application in creating a sufficiently strong tubular structure for a transport
container. Moreover, with the intended use being a transport container, rather than
a press fabric where a smooth transition between fabric strips is desired, this is
not a particular concern and different joining methods (overlapping and sewing, bonding,
stapling, etc.) are possible. Other types of joining may be apparent to one skilled
in the art.
[0013] Furthermore, while as aforenoted, a seamless flexible container is desirable and
has been mentioned in the prior art, the means for manufacturing such a structure
has its difficulties. Heretofore, as noted, large flexible containers were typically
made in smaller sections which were sewn or bonded together. These sections had to
be water impermeable. Typically such sections, if not made of an impermeable material,
could readily be provided with such a coating prior to being installed. The coating
could be applied by conventional means such as spraying or dip coating.
[0014] Another problem is when the container is empty, since it is typically denser than
salt water, it will sink in the absence of cargo. Devices that add buoyancy may be
affixed to the container to prevent this.
[0015] In addition, due to the sinking during emptying of the cargo, because of this, in
the absence of such devices the container may tend to bow in the middle which is undesirable.
Summary of the Invention
[0016] It is therefore a principal object of the invention to provide for a relatively large
fabric FFCV for the transportation of cargo, including, particularly, fresh water,
having a density less than that of salt water and being so formed so as to be impervious
to salt water and salt water ions.
[0017] It is a further object of the invention to provide for such an FFCV which has means
of rendering the FFCV buoyant, particularly when empty without the need for buoyancy
devices.
[0018] These and other objects and advantages will be realized by the present invention.
In this regard the present invention envisions the use of a woven or spirally formed
tube to create the FFCV, having a length of 300' or more and a diameter of 40' or
more. Such a large structure can be fabricated on machines that make papermaker's
clothing. The ends of the tube, sometimes referred to as the nose and tail, or bow
and stern, may be sealed by a number of means, including being pleated, folded or
otherwise reduced in diameter and bonded, stitched, stapled or maintained by a mechanical
coupling or other means set forth in the aforesaid applications.
[0019] As aforenoted, the rendering of such a large vessel impervious to salt water and
salt water ions, especially one formed seamless has its difficulties. In the aforesaid
second application, means to accomplish this are disclosed. The present invention
expands upon this and allows for different coatings to be incorporated into the FFCV.
In addition, the present invention discloses coating methods which serve not only
to render the fabric of the FFCV impervious but also buoyant with or without cargo
(i.e. fresh water).
[0020] In the first aspect of the invention, it provides for a fabric making up the FFCV
having a coated face or outside and back or inside with a thermoplastic material which
may be different. The advantage of having different coatings on the inside and outside
can be for a multitude of reasons. For example, it may be desirable to include a UV
protecting ingredient in or on the outer coating. The coating selected may be influenced
by this. On the inside there would be no need for a UV protection. However, it may
be desirable to include a germicide or fungicide in or on the inside coating. Again,
the coating selection may be influenced by this.
[0021] Other considerations may come into play as to the advantage of different coatings
on the FFCV which will be apparent to a skilled worker in the art.
[0022] Such a coating arrangement may be implemented by applying coating to the fiber or
yarn that makes up the fabric prior to the weaving thereof. In this regard, the face
fibers may be coated with one type of thermoplastic compound with the back fibers
coated with a different thermoplastic compound. The weaving process selectively interlaces
all fibers with one type coating on one side and with the other coating on the other
side. The structure is then heat treated under pressure to enable the thermoplastic
coating to liquify and render the fabric impermeable. The different coatings predominantly
stay on the sides of the fibers where they originated from.
[0023] We turn now to further ways to implement a coating of the fabric with additional
attendant advantages. In this regard, the present invention envisions providing a
coating that not only renders the fabric impermeable, but also allows the FFCV to
float due the buoyant nature of the coating. A first way is to spray coat the fabric
with the desired coating. In this regard, the desired result is to create an FFCV
which includes the fabric and coating which has an overall density of less than that
of salt water which is approximately 1.0 g/cm
3.
[0024] Accordingly, decreasing the overall density can be effected in the following ways.
By incorporating microspheres (which may be glass, polymers, or other material suitable
for purpose) in the coating, it creates voids in the coating, albeit small ones. Sufficient
amounts of microspheres are added such that the density of the coating is reduced
to less than 1.0 g/cm
3. The amount the density is reduced will also be dictated by the density of the woven
fibers and the desired physical properties of the coating. For example, if the fibers
used will themselves float uncoated, then the coating density need only be reduced
sufficiently that it will float. In such an instance, the composite structure or coated
fabric will naturally float.
[0025] If, however, the fibers used do not themselves float, then the density of the coating
could be adjusted to compensate for the added density of the fibers such that the
overall density of the composite structure is less than 1.0 g/cm
3.
[0026] Of course, in doing so, the desired mechanical characteristics of the coating should
not be compromised beyond that required for an effective FFCV. For example, sufficient
tensile strength, flexibility and abrasion resistance of the coating should be maintained
to the degree necessary, as will be apparent to one skilled in the art.
[0027] Turning now briefly to a further means to provide for an FFCV with sufficient buoyancy,
in this regard it again relates to the coating used to render the fabric impervious.
In addition to creating a foam coating in the traditional manner, it has been found,
quite unexpectedly, that air entrained in the spraying of the coating onto the fabric
results in air bubbles within the coated fabric. Such air bubbles lower the density
of the coating which, if to a sufficient degree, allows the coated fabric to be buoyant.
The air bubbles were found to be both random in size and location and varied due to
spraying conditions. The randomness of such voids may serve to minimize, to a certain
degree, the effect that they may have on the mechanical characteristics as aforediscussed.
Brief Description of the Drawings
[0028] Thus by the present invention its objects and advantages will be realized, the description
of which should be taken in conjunction with the drawings, wherein:
Figure 1 is a somewhat general perspective view of an FFCV which is cylindrical having
a pointed bow or nose;
Figure 2 is a side sectional view of a fabric incorporating the teachings of the present
invention;
Figures 2A and 2B illustrate the stitching points of the front and back weave of the
fabric shown in Figure 2 incorporating the teachings of the present invention;
Figure 3 is a side sectional view of a coated fabric incorporating microspheres in
its coating, incorporating the teachings of the present invention;
Figure 3A is a graph illustration of a stress strain curve for resin without microsphere
and with two different microspheres.
Figure 4 is a side sectional view of a coated fabric having an air entrained coating,
incorporating the teachings of the present invention;
Figure 4A is an enlargement of a portion of the coating shown in Figure 4 incorporating
the teachings of the present invention;
Figure 5 is a perspective view of a device for applying heat and pressure to a tube
which is to be used in an FFCV incorporating the teachings of the present invention;
and
Figure 6 is a perspective view of the device shown in Figure 5 in conjunction with
the tube incorporating the teachings of the present invention.
Detailed Description of the Preferred Embodiments
[0029] The proposed FFCV 10 is intended to be constructed of a seamless woven impermeable
textile tube 12. The tube's configuration may vary. For example, it would comprise
a tube having a substantially uniform diameter (perimeter) and sealed on each end
as shown in Figure 1. It can also have a non-uniform diameter or non-uniform shape.
The respective ends may be closed, pinched, and sealed in any number of ways. The
resulting coated structure will also be flexible enough to be folded or wound up for
transportation and storage.
[0030] The aforesaid patent applications discuss design consideration, material used, features
and advantages of certain constructions, among other things, and will not be repeated
herein. In general however, the material used will be briefly discussed.
[0031] Since the FFCV will experience cycling between no load and high load, the material's
recovery properties in a cyclical load environment should be considered in any selection
of material. The materials must also withstand exposure to sunlight, salt water, salt
water temperatures, marine life and the cargo that is being shipped. The materials
of construction must also prevent contamination of the cargo by the salt water. Contamination
would occur, if salt water were forced into the cargo or if the salt ions were to
diffuse into the cargo.
[0032] The present invention envisions the fabrication of very large FFCVs which are constructed
from coated textiles. Coated textiles have two primary components. These components
are the fiber reinforcement and the polymeric coating. A variety of fiber reinforcements
and polymeric coating materials are suitable for FFCVs. Such materials must be capable
of handling the mechanical loads and various types of extensions which will be experienced
by the FFCV. Such materials, particularly the coating used, should also be abrasion
resistant, since it will probably come in contact with objects during towing. Also,
since it is envisioned that the FFCV be collapsed and wound onto a reel, it will come
into contact with surfaces of the towing vessel when it is wound and unwound, so the
material selected should be resistant to abrasion as a result of such contact. In
addition, the materials used should be selected with the cargo being transported being
taken into consideration. For example, if the cargo is potable water, the materials
used, particularly the coating on the inside of the FFCV, should be acceptable for
use with potable water. The coating used may even be the subject of approval by a
governmental agency such as the FDA, if the potable water is to be used within its
jurisdiction, or if not, a government agency of a foreign country where such water
is to be used. Accordingly, a coating which might leach harmful chemicals or otherwise
contaminate the cargo should not be used on the inside of the FFCV. Leaching should
also be avoided if, for example, a germicide, fungicide or UV stabilizer is incorporated
into the coating. A loss of it by leaching might compromise the desired result being
sought. Other considerations as to the coating selected will be readily apparent to
the skilled artisan depending upon the nature of the cargo being transported and the
end result desired.
[0033] Suitable polymeric coating materials include polyvinyl chloride, polyurethanes, synthetic
and natural rubbers, polyureas, polyolefins, silicone polymers and acrylic polymers.
These polymers can be thermoplastic or thermoset in nature. Thermoset polymeric coatings
may be cured via heat, room temperature curable or UV curable. The polymeric coatings
may include plasticizers and stabilizers that either add flexibility or durability
to the coating. The preferred coating materials are plasticized polyvinyl chloride,
polyurethanes and polyureas. These materials have good barrier properties and are
both flexible and durable.
[0034] Suitable fiber reinforcement materials are nylons (as a general class), polyesters
(as a general class), polyaramids (such as Kevlar®, Twaron® or Technora®), polyolefins
(such as Dyneema® and Spectra® which are made of ultra high molecular weight polyethylene)
and polybenzoxazole (PBO).
[0035] Within a class of material, high strength fibers minimize the weight of the fabric
required to meet the design requirement for the FFCV. The preferred fiber reinforcement
materials are high strength nylons, high strength polyaramids and high strength polyolefins.
PBO is desirable for its high strength, but undesirable due to its relative high cost.
High strength polyolefins are desirable for their high strength, but difficult to
bond effectively with coating materials.
[0036] Accordingly, with all of the foregoing in mind, the appropriate fiber and weave may
be selected along with the coating to be used.
[0037] Turning now to a method of rendering such a large structure impermeable, there are
several ways to accomplish this which are set forth in the aforesaid patent applications
and will not be repeated herein.
[0038] However, as discussed in the aforesaid applications, one of the methods for coating
the tube employs a thermoplastic composite approach. The tube is woven from a mixture
of at least two fibrous materials. One material would be the reinforcing fiber and
the second material would be a low melting fiber or low melting component of a reinforcing
fiber. The low melting fiber or component might be a thermoplastic polyurethane or
polyethylene. The reinforcing fiber might be polyester or nylon tire cord or one of
the other fibers hereinbefore discussed. The tube would be subjected to heat and pressure
in a controlled fashion. This heat and pressure would cause the low melting fiber
or component to melt and fill the void in the woven structure. After the heat and
pressure are removed and the structure is cooled, a composite structure would form
in which the low melting fiber or component has become the matrix for the reinforcing
fiber. This approach requires applying heat and pressure while also providing a means
to keep the inner surfaces of the tube from adhering or thermally bonding to each
other.
[0039] The present invention is directed to a variation thereof so as to provide for a fabric
having two different coatings on opposite sides of the fabric. In this regard, the
method involves applying a coating to the fibers or yarns that make up the fabric
20 prior to the weaving operation. The face fibers 22 are coated with one type of
thermoplastic compound and said back fibers 24 are coated with a different thermoplastic
compound as shown in Figure 2. The weaving process selectively interlaces all the
fibers with one type of coating on the face side 26 and all the fibers of another
coating on the backside 30. The two layers are bound together by a weaving technique
called stitching points. This stitching point technique is illustrated when viewing
Figure 2 in combination with Figures 2A and 2B. In this regard, fibers 22 and 24,
which have the thermoplastic coating, have the great majority of their length on surfaces
26 and 30 respectively. This is due to the use of stitching points 32 in the weave.
While the weave shown is generally referred to as an 8 harness, satin double cloth
with stitching points, any weave suitable for the purpose can be used.
[0040] The core fibers, prior to coating with the thermoplastic material, can be made of
polyamide, polyester, aramid, polyolefin, rayon, fiberglass or any yarn system compatible
with fiber coating systems. The coating of this core fiber is done in a fashion known
to those skilled in the art. There are many denier sizes that could be used ranging
from 210 denier all the way to 10,000 denier depending on the thickness of the fabric
desired and the strength requirement that must be achieved.
[0041] The thermoplastic coating can be.a urethane, polyester, polyamide, polyvinyl chloride,
polyolefin, or the like. The melting temperature of the coating material must be substantially
lower than the melting temperature of the core fiber so there is no damage to the
core fiber during coating application or post heat treating.
[0042] One very common coated fiber is that of polyvinyl chloride (PVC) over polyamide multifilament.
This fiber is traditionally used to fabric braid electrical wire harnesses. Another
common coated fiber is thermoplastic urethane coated over polyamide multifilament.
This fiber is traditionally used in the manufacture of outdoor furniture. Both of
these fibers can be woven on the large papermaker clothing looms to produce a structure
that is a double cloth weave with stitching points in an endless form. The resulting
structure is tubular and contains no seams but is still permeable to water and air.
To render the woven fabric impermeable to air and water it must be treated with heat
and moderate pressure to make the coatings flow on the individual fibers. Each coating
system will flow on the respective side of the fabric and create a homogeneous barrier
to air and water. After the tube is woven, the coatings on the fibers 22 and 24 are
liquified by being subject to heat and pressure.
[0043] One way to do this is set forth in the second aforesaid patent application and involves
a device 71 shown in Figures 5 and 6 which can apply heat and pressure to the tube
12. The device 71 can be self-propelled or can be moved by external pulling cables.
Each section 73 and 74 of the device includes heating or hot plates with respective
magnets 76 and motors (not shown) and are positioned on either side of the fabric
as shown in Figure 6. A power supply (not shown) is provided to energize the heating
plates 76 and supply power to the motors that propel the device across the tube 12.
The magnets serve to pull the two hot plates 76 together which creates pressure to
the fabric as the coating on the yarn liquefies from the heat. These magnets also
keep the top heating plate 76 opposite to the inside heating plate 76. The device
71 includes endless non-stick belts 78 that ride on rollers 80 located at the plate
ends. The belts 78 ride over the plates 76. In this way there is no movement of the
belt 78 in relation to the fabric surface when it is in contact with the fabric. This
eliminates smearing of the melted coating and uniform distribution between the yarns.
The device moves across the length of the tube 12 at a speed that enables the melted
coat to set prior to the fabric folding back upon itself and sticking. If faster speeds
are desired, a means for temporarily keeping the inside surfaces apart while setting
takes place, may be implemented. This may be, for example, a trailing member on the
inside of the tube of similar design to that described but being only one section
without, of course, a heating plate or magnet. Other means suitable for this purpose
will be readily apparent to those skilled in the art.
[0044] In view of the closed nature of the FFCV, if it is intended to transport fresh water,
as part of the coating process of the inside thereof, it may provide for one of the
coatings to include a germicide or a fungicide so as to prevent the occurrence of
bacteria or mold or other contaminants.
[0045] In addition, since sunlight also has a degradation effect on fabric, the FFCV may
include as part of its outside coating a UV protecting or stabilizing ingredient in
this regard.
[0046] Turning now to a further embodiment for coating the FFCV, an FFCV constructed from
materials such as, for example, nylon, polyester and rubber would have a density greater
than salt water. As a result the empty FFCV or empty portions of the large FFCV would
sink. This sinking action could result in high stresses on the FFCV and could lead
to significant difficulties in handling the FFCV during filling and emptying of the
FFCV. The use of a coating, which provides buoyancy, provides an alternative to mechanical
buoyancy devices.
[0047] As aforesaid, it is desirable that the FFCV float when empty of cargo. This may be
accomplished by any number of means including those set forth in the patent applications
noted earlier. Including therein is to coat the FFCV with a foam. By using a foam
coating, one could lower the overall density of the coated fabric to below 1.0 g/cm
3, since the yarns or fibers used such as polyester and coating resins, such as polyvinyl
chloride have densities greater than 1.0 g/cm
3. Foamed coatings usually involve generating a large amount of gas chemically in the
coating or by purposely beating air into the coating by a mechanical device. Applying
foam has its advantages and may be desirable under certain circumstances. Applying
foam also has some drawbacks, since it is difficult to control penetration, uniformity
and thickness. Also, foam has less abrasion resistance and mechanical strength to
that of a non-foamed resin coating.
[0048] A proposed alternative, in addition to foaming, is to incorporate microspheres into
the coating. There are generally two types of microspheres glass and polymeric. The
bulk densities are as low as .01 g/cm
3 with mean particle size ranges of about 100 microns. Such microspheres are manufactured
by 3M and PQ Corp. PQ Corp. sells plastic microsphere filler under the designation
PM 6545 and PM 6550.
[0049] PM 6545 and PM 6550 are produced from a copolymer consisting of polyacrylonitrile
and polymethacrylonitrile. The plastic spheres products are resistant to solvents
and resins. The following is a table of their characteristics.
Table 1
|
Density.(g/cc) |
Volume Particle Size (µ) |
|
Product Grade |
Bulk |
Effective |
Mean |
Range |
Working Pressure (psi) |
PM 6545 |
0.009 |
0.020 |
110 |
10-250 |
2000 |
PM 6550 |
0.010 |
0.022 |
100 |
10-250 |
2000 |
PQ Corp. also supplied a hollow, glass microsphere, Q-Cel 6019S. This material is
easier to work with but is somewhat denser at 0.19 g/cm
3.
[0050] As can be seen in the following example, by providing 14% loading of microspheres
by volume, the densities of the coating were reduced to 0.95 g/cm
3. Note that the desired overall density for the finished product and the necessary
loading will vary depending upon the resin and the fabric. Also, while the physical
properties of the coating are lower, it should not be so low so as to effect the integrity
of an FFCV.
Example
Resin and curative:
[0051] Adiprene® LF 950 (urethane prepolymer) - 1.13 g/cm
3 Ethacure® 100 (curative) - 1.022 g/cm
3
[0052] For 95% stochiometry, 11 parts of Ethacure 100 was mixed with 100 parts of Adiprene.
Note, the amount of microspheres used was based only with regard to the Adiprene.
The curative should, however, also be taken into account.
[0053] To float in water, the polyurethane coating must have a density of less than 1.0
g/cm
3. A density 0.95 g/cm
3 would be effective. Note that the density of the fabric should also be taken into
account. In practice, the urethane will need to be low enough in density to float
both it and the fabric to which it has been applied.
Sample ID |
Adiprene LF950 |
Ethacure 100 |
PM6550 |
Q-Cel 6019S |
5017-08A |
100g |
11g |
X |
X |
5017-08B |
100g |
11g |
0.38g |
X |
5017-08C |
100g |
11g |
X |
3.13g |
Table 2 - formulation information
Sample ID |
Density (calculated) |
Microsphere % by volume |
5017-08A |
~ 1.13 |
X |
5017-08B |
~ 0.95 |
14.8 |
5017-08C |
~ 0.95 |
14.3 |
[0054] The microspheres were mixed into the Adiprene prepolymer without much difficulty.
The PM 6550 microspheres were more difficult to work with due to their low density.
Samples of each resin mix were cast into molds, allowed to cure, trimmed to size,
and then tested for tensile strength.
[0055] There was some reduction in strength of the coating for both the PM 6550 and the
Q-Cel 6019S observed as can be seen in Figure 3A. In this regard, unfilled resin is
illustrated by line 60, resin filled with PM 6550 is illustrated by line 62 and resin
filled with Q-Cel 6019S being illustrated by line 64. Tests for flexibility and abrasion
should also be performed.
[0056] Accordingly, by incorporation of microspheres, it will decrease the density of a
resin to the point of buoyancy in seawater. Resin properties will be affected but
should be adequate for the requirements of the particular application. It should be
noted that spray application of polyurethanes and in particular, polyureas is typically
done at high pressure, i.e. in excess of 1000psi. The microspheres selected should
be capable of handling such pressures.
[0057] Figure 3 shows a coated fabric 40. In this regard, there is a base substrate 42 which
may be woven, knit or braided from a desired yarn or fiber. The fabric 40 is coated
on both sides 44 and 46 with the desired resin. Incorporated into the resin prior
to its being applied (via spraying, etc.) are the microspheres 48 as aforedescribed.
The microspheres 48 are randomly disbursed in the coating and create sufficient voids
such that the overall density of the fabric 40 is less than 1 g/cm
3. Accordingly, an FFCV made with such a fabric will float in salt water with or without
a cargo of fresh water.
[0058] Turning now to an alternative means of rendering the fabric buoyant, in this regard
reference is made to Figures 4 and 4A. In many applications, in general, where a coating
is being applied, entrained air in the coating is undesirable. This is in contradistinction
to a foam coating as aforementioned, and steps are often undertaken to prevent entrained
air from becoming entrapped in the coating.
[0059] The present invention is just the reverse of this. In order to reduce the overall
density of the coated fabric 50 air is allowed to become entrapped within the coating
52. As can be seen in Figure 4A, air bubbles 54 of random size and placement are entrapped
in the coating 52. The amount of entrapped air necessary will vary depending upon
the density of the fibers and the resin used. The goal is, however, to have the overall
density of the coated fabric to be less than 1 g/cm
3.
[0060] For example, a fabric was woven from ultra-high molecular weight polyethylene (UHMWPE)
fiber (tradenames for these are Spectra® or Dyneema®) and then coated with a spray-applied,
2 component polyurethane system containing no fibers, simply a pure polyurethane coating.
[0061] Although it was expected that the UHMWPE fabric would float (density 0.97 g/cm
3), it was also expected that after coating with polyurethane (density of approximately
1.17 to 1.27 g/cm
3), any floating characteristics of the fabric would be negated by the much denser
coating. Coating add-on is at least 1:1 and more typically, 2:1 and even 3:1 coating
to fabric ratio.
[0062] When a sample of spray coated fabric was placed in water, it floated. Since the coating
was applied via a spray process, air was trapped in the coating during spraying, effectively
reducing the density to something less than 1.0 g/cm
3. Note that coating density will vary depending particularly on spraying conditions.
Also, the density of the coated fabric will vary depending on the coating to fabric
ratio.
[0063] As in the case of microspheres, there is a trade off in the mechanical strength of
the coated fabric with the advantage of the fabric's ability to float. Obviously,
such a trade off should not be to such an extent that the integrity of the FFCV is
compromised.
[0064] Also, in either situation, it may be desirable to have the filled coatings having
entrained air or microspheres on top of or beneath an unfilled coating. The filled
coatings could also be sandwiched between the unfilled coatings or any variations
along these lines, such as coating the interior of the tube with filled coating and
the exterior of the tube with unfilled coating. The variations are endless.
[0065] In addition, it may be desirable to have the entire tube coated with filled coatings
or only a portion thereof or at selected locations with the other portions or locations
coated with an unfilled coating. All of this would depend on the desired results being
sought.
[0066] Although preferred embodiments have been disclosed and described in detail herein,
their scope should not be limited thereby rather their scope should be determined
by that of the appended claims.
1. A flexible fluid containment vessel (10) for the transportation and/or containment
of cargo comprising a fluid or fluidisable material, said vessel (10) comprising:
an elongated flexible tubular structure comprised of fabric (40) having a first side
(44) and a second side (46); said tubular structure being impervious and having a
front end and a rear end;
means for sealing said front end and said rear end;
means for filling and emptying said vessel (10) of cargo; and characterised in
means for rendering said tubular structure buoyant having said fabric (40) at least
one thermoplastic or thermoset coating (52) that renders the fabric (40) buoyant.
2. The vessel in accordance with claim 1 wherein said fabric (40) is woven and said first
and second sides (44, 46) are formed by stitching points (32).
3. The vessel in accordance with claim 1 wherein said fabric (40) is formed out of yarns,
and said at least one thermoplastic coating (52) is subject to heat, pressure or both
to cause it to flow and fill voids in said fabric (40).
4. The vessel in accordance with claim 1 wherein a first thermoplastic coating is on
said first side (44) of the fabric (40) and said second thermoplastic coating is on
a second side (46) of the fabric with said first thermoplastic coating being different
from said second thermoplastic coating with said coatings being taken from the group
consisting essentially of urethane, polyester, polyamide, polyvinyl chloride, polyolefin
or other suitable thermoplastic material.
5. The vessel in accordance with claim 1 wherein said means for rendering said tubular
structure buoyant comprises coating one or both sides of said fabric (40) with a coating
having microspheres (48) therein in a sufficient amount that the overall density of
the coated fabric (40) approximately 1.0 g/cm3 or less.
6. The vessel in accordance with claim 5 wherein said coating is taken from the group
consisting essentially of: polyvinyl chloride, polyurethanes, synthetic and natural
rubbers, polyureas, polyolefins, silicone polymers, acrylic polymers or foam derivatives
thereof.
7. The vessel in accordance with claim 1 wherein said means for rendering said tubular
structure buoyant comprises coating one or both sides (44, 46) of said fabric (40)
with a coating having a gas or entrained air in the coating such that the gas or air
is trapped within the coating in sufficient amount that the overall density of the
coated fabric is approximately 1.0 g/cm3 or less.
8. The vessel in accordance with claim 7 wherein the coating is applied to the fabric
by spraying or in the form of a foam.
9. The vessel in accordance with claim 7 wherein said coating is taken from the group
consisting essentially of: polyvinyl chloride, polyurethanes, synthetic and natural
rubbers, polyureas, polyolefins, silicone polymers, acrylic polymers or foam derivatives
thereof.
10. The vessel in accordance with claim 1 wherein the fabric includes fibers or yarns
(20, 22) made from material consisting essentially of ultra high molecular weight
polyethylene, or polyolefins; and the means for rendering said tubular structure buoyant
comprises coating said fabric with a polyurethane material.
11. The vessel in accordance with claim 10 wherein said coating is a thermoset polyurethane
coating.
1. Flexibles Gefäß für Flüssigkeiten (10) für den Transport und/oder die Aufbewahrung
von Fracht, welche ein flüssiges oder verflüssigbares Material umfaßt, wobei das Gefäß
(10) folgende Merkmale umfaßt:
ein längliches, flexibles, röhrenförmiges Gebilde, das von einem Gewebe (40) umfaßt
wird und das eine erste Seite (44) und eine zweite Seite (46) hat;
wobei das röhrenförmige Gebilde undurchlässig ist und ein vorderes Ende und ein hinteres
Ende hat;
Mittel zum Verschließen des vorderen Endes und des hinteren Endes;
Mittel zum Befüllen und Entleeren des Gefäßes (10) mit Fracht und gekennzeichnet durch
Mittel, um das röhrenförmige Gebilde schwimmfähig zu machen, wobei das Gewebe (40)
mindestens einen thermoplastischen oder wärmeausgehärteten Überzug (52) hat, der das
Gewebe (40) schwimmfähig macht.
2. Gefäß nach Anspruch 1, wobei das Gewebe (40) gewebt ist und die ersten und zweiten
Seiten (44, 46) durch Nahtpunkte (32) ausgebildet sind.
3. Gefäß nach Anspruch 1, wobei das Gewebe (40) aus Garn gebildet ist und wobei der zumindest
eine thermoplastische Überzug (52) Hitze, Druck oder beidem unterworfen wird, um ihn
fließen zu lassen und Hohlräume in dem Gewebe (40) auszufüllen.
4. Gefäß nach Anspruch 1, wobei ein erster thermoplastischer Überzug auf der ersten Seite
(44) des Gewebes (40) und der zweite thermoplastische Überzug auf einer zweiten Seite
(46) des Gewebes ist, wobei der erste thermoplastische Überzug von dem zweiten thermoplastischen
Überzug verschieden ist, wobei die Überzüge aus der Gruppe, bestehend im wesentlichen
aus Urethan, Polyester, Polyamid, Polyvinylchlorid, Polyolefin oder anderen geeigneten
thermoplastischen Materialien, genommen werden.
5. Gefäß nach Anspruch 1, wobei die Mittel, um das röhrenförmige Gebilde schwimmfähig
zu machen, umfassen, daß eine oder beide Seiten des Gewebes (40) mit einem Überzug,
der Mikrosphären (48) darin in einer genügenden Menge hat, überzogen werden, so daß
die Gesamtdichte des überzogenen Gewebes (40) ungefähr 1,0 g/cm3 oder weniger beträgt.
6. Gefäß nach Anspruch 5, wobei der Überzug aus der Gruppe, bestehend im wesentlichen
aus Polyvinylchlorid, Polyurethanen, synthetischen und natürlichen Gummis, Polyharnstoffen;
Polyolefinen, Silikonpolymeren, Acrylpolymeren oder Schaumstoffderivaten davon, genommen
werden.
7. Gefäß nach Anspruch 1, wobei die Mittel, um das röhrenförmige Gebilde schwimmfähig
zu machen, umfassen, daß eine oder beide Seiten (44, 46) des Gewebes (40) überzogen
werden, wobei der Überzug ein Gas oder mitgeführte Luft in dem Überzug hat, so daß
das Gas oder die Luft in dem Überzug in einer genügenden Menge eingeschlossen ist,
so daß die Gesamtdichte des überzogenen Gewebes ungefähr 1,0 g/cm3 oder weniger beträgt.
8. Gefäß nach Anspruch 7, wobei der Überzug auf das Gewebe durch Sprühen oder in der
Form eines Schaumes aufgebracht wird.
9. Gefäß nach Anspruch 7, wobei der Überzug aus der Gruppe, bestehend im wesentlichen
aus Polyvinylchlorid, Polyurethanen, synthetischen oder natürlichen Gummis, Polyharnstoffen,
Polyolefinen, Silikonpolymeren, Acrylpolymeren oder Schaumstoffderivaten davon, genommen
wird.
10. Gefäß nach Anspruch 1, wobei das Gewebe Fasern oder Garne (20, 22) beinhaltet, die
aus einem Material gemacht sind, das im wesentlichen aus ultrahochmolekulargewichtigem
Polyethylen oder Polyolefinen besteht, und wobei die Mittel, um das röhrenförmige
Gebilde schwimmfähig zu machen, umfassen, daß das Gewebe mit einem Polyurethanmaterial
überzogen wird.
11. Gefäß nach Anspruch 10, wobei der Überzug ein wärmeausgehärteter Polyurethanüberzug
ist.
1. Récipient flexible (10) de confinement d'un fluide pour le transport et/ou le confinement
d'un chargement comprenant un matériau fluide ou susceptible d'être fluidisé, ledit
récipient (10) comprenant :
une structure tubulaire flexible allongée faite de tissu (40) ayant un premier côté
(44) et un second côté (46) ; ladite structure tubulaire étant étanche et ayant une
extrémité avant et une extrémité arrière ;
un moyen pour sceller ladite extrémité avant et ladite extrémité arrière ;
un moyen pour remplir et vider ledit récipient (10) de chargement ; et
caractérisé en ce qu'un moyen destiné à rendre ladite structure tubulaire flottante ayant ledit tissu (40)
comprend au moins un revêtement thermoplastique ou thermodurcissable (52) qui rend
le tissu (40) flottant.
2. Récipient selon la revendication 1 dans lequel ledit tissu (40) est filé et lesdits
premier et second côtés (44, 46) sont formés par des points de couture (32).
3. Récipient selon la revendication 1 dans lequel ledit tissu (40) est formé de fils,
et ledit au moins un revêtement thermoplastique (52) est soumis à une chaleur, une
pression ou les deux afin de le faire s'écouler et remplir des vides dans ledit tissu
(40).
4. Récipient selon la revendication 1 dans lequel un premier revêtement thermoplastique
est sur ledit premier côté (44) du tissu (40) et ledit second revêtement thermoplastique
est sur un second côté (46) du tissu avec ledit premier revêtement thermoplastique
étant différent dudit second revêtement thermoplastique avec lesdits revêtements étant
pris dans le groupe constitué essentiellement d'uréthane, de polyester, de polyamide,
de chlorure de polyvinyle, de polyoléfine ou autre matériau thermoplastique approprié.
5. Récipient selon la revendication 1 dans lequel ledit moyen destiné à rendre ladite
structure tubulaire flottante comprend de revêtir un ou les deux côtés dudit tissu
(40) avec un revêtement ayant des microsphères (48) à l'intérieur en une quantité
suffisante de manière à ce que la densité totale du tissu revêtu (40) soit approximativement
de 1,0 g/m3 ou moins.
6. Récipient selon la revendication 5 dans lequel ledit revêtement est pris dans le groupe
constitué essentiellement: d'un chlorure de polyvinyle, de polyuréthanes, de caoutchoucs
synthétiques et naturels, de polyurées, de polyoléfines, de polymères de silicone,
de polymères d'acrylique ou de dérivés mousseux de ceux-ci.
7. Récipient selon la revendication 1 dans lequel ledit moyen destiné à rendre ladite
structure tubulaire flottante comprend de revêtir un ou les deux côtés (44, 46) dudit
tissu (40) avec un revêtement ayant un gaz ou de l'air entrainé dans le revêtement
de telle manière que le gaz ou l'air soit piégé à l'intérieur du revêtement en une
quantité suffisante de manière à ce que la densité totale du tissu revêtu soit approximativement
de 1,0 g/m3 ou moins.
8. Récipient selon la revendication 7 dans lequel le revêtement est appliqué au tissu
en pulvérisant ou sous la forme d'une mousse.
9. Récipient selon la revendication 7 dans lequel ledit revêtement est pris dans le groupe
constitué essentiellement: d'un chlorure de polyvinyle, de polyuréthanes, de caoutchoucs
synthétiques et naturels, de polyurées, de polyoléfines, de polymères de silicone,
de polymères d'acrylique ou de dérivés mousseux de ceux-ci.
10. Récipient selon la revendication 1 dans lequel le tissu inclut des fibres ou des fils
(20, 22) faits de matériau constitué essentiellement de polyéthylène a poids moléculaire
ultra élevé, ou de polyoléfines ; et le moyen destiné à rendre ladite structure tubulaire
flottante comprend de revêtir ledit tissu avec un matériau de polyuréthane.
11. Récipient selon la revendication 10 dans lequel ledit revêtement est un revêtement
de polyuréthane thermodurcissable.