Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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STRETCHABLE SHEETS COMPRISING A VARIETY OF LAYERS AND ZONES
AND METHODS TO PRODUCE SUCH PRODUCTS
FIELD OF THE INVENTION
The present invention relates to products and sheets such as two-dimensional
and
three-dimensional products and sheets, composed of flexible, stretchable
and/or elastic
materials such as natural elastomers and other synthetic polymers. The
invention also relates
to methods for layering additional material such as fibers, in order to make
2D and 3D
stretchable and/elastic products.
BACKGROUND OF THE INVENTION
This application is an improvement to our pending U.S. Patent Application No.
12/875,716. Said application introduced a product produced by a method for
producing a
stretchable nonwoven sheet, comprising a stretchable material such as natural
rubber and
loose fibers on a workpiece former such as conveyor belt or mold. In this
current application,
we wish to introduce some new features to the products characteristics to
further expand
products utilizations and applications.
SUMMARY OF THE INVENTION
The present invention is related to methods for producing a variable layered
sheet of
stretchable, elastic or shape-retaining products, composed principally of
materials such as
resilient elastomets including, but not limited to, natural latex rubber or
polyurethane, using
variety of controlled spraying units for spraying the principal material or
materials onto a
surface of a wall such as a workpiece former. The resulting product is a sheet
having at
least two different zones unified within the sheet. The present invention is
also directed to
improved methods for preparing products having a single or double-sided
surface coating
of same or different types of loose fibers, and a method for generating same
or different
microporosity regions in such products.
The present invention discloses a sheet with different thicknesses, composites
and
structures in different areas. The creation of such sheet or fabric is very
similar to "3D
printing."
Creating nonwoven disposable fabric, by using the disclosed technology, is in
fact
3D printing of fabric.
In one aspect, the invention provides sheets comprising two or more zones,
wherein
at least one zone is characterized by a different composite and features than
one of the
remaining zones; and the sheet is stretchable and non-woven.
In another aspect, the invention provides methods for producing a stretchable
workpiece comprising applying one or more materials on a conveyor or a mold
using
different machines or compartment or different materials in different layouts
so to produce
a workpiece having two or more zones, wherein at least one zone comprises a
different
material feature than one of the remaining zones.
In certain embodiments there is provided a method for producing a non-woven
and
stretchable workpiece, comprising: applying, using a controlled spraying, of a
material, in
a liquid form, for forming the workpiece onto a surface of a wall on a
conveyor or a mold
so to produce, at the same time, a workpiece having two or more zones, wherein
at least
one zone comprises a different material feature than one of the remaining
zones; and
wherein two adjacent zones are blended at their connection lines, creating a
continuous
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seamless workpiece; and wherein the material feature is selected from the
group
consisting of polymer type, porosity, liquid permeability, breathability, tear
strength,
elongation at break, retractive force after extension, tensile strength,
colour, odor, density,
tactile feel, and fibre type.
These and other embodiments of the invention will become apparent in light of
the
detailed description below.
BRIEF DESCRIPTION OF THE FIGURES
The following figures show examples for two possible embodiments of this
invention:
Fig. 1 represents a section through a sheet of this invention, the sheet
having two
zones - Zone I (left) and Zone 2 (right). Each zone comprises three layers.
The upper layer
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of both zones is made out of composite 1. The middle layer of Zone 1 is made
out of
composite 2, while the middle layer of zone 2 is made out of composite 3. The
bottom layer
of zone 1 is made out of composite 3, while the bottom layer of zone 2 is made
out of
composite 2.
Fig. 2 represents a section through a sheet of this invention, the sheet
having the same
structure as described in Fig 1, and further comprising additional layer of
composite 4 built
on top of the upper layer (composite 1) at a specific location, covering zone
1 in full but only
part of zone 2. This specific structure creates differences in the thickness
of the different
areas of the sheet.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is generally related to stretchable, elastic or shape-
retaining
products composed of principal materials comprising resilient elastomers such
as natural
latex rubber, polyurethane or other synthetic materials, in a spray able
liquid state, and
methods for producing such products, using a controlled spraying of the liquid
material onto
a surface of a wall such as a workpiece former. The resulting product is a
sheet having at
least two different zones as desired. The present invention is also directed
to products having
a single or double-sided fiber flocked surface, and products such as non-woven
sheets having
desired level of porosity at each different zone, in order to gain
breathability or permeability
at the different zones of such products. The present invention is also
directed to products
produced by the inventive methods. The product produced by the invention has
improved
specifications and feeling on both sides of the product. The unified sheet
allows the creation
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of a product with different performances at different areas, without the need
to attach together
different sheets of different materials.
The phrase 'unified within the sheet' means the composites of two zones
adjacent
one to the other, are blended at their connection lines, creating a continuous
seamless sheet.
The term "flock" or "flocking" refers to the process of applying, attaching,
or
adhering loose fibers onto a surface.
The terms "former," "mould," or "workpiece former" are used interchangeably. A
former or mould is an object made of any desired shape or size and serves as
shape former
for the making of products. For example, if a product in the shape of a face
mask is desired,
then a former or mould may be constructed that displays the shape and size of
desired face
mask. The former may be flat and two-dimensional such as a flat belt conveyor.
Alternatively, the former may be three-dimensional and have a complex shape to
which a
workpiece substantially conforms. In addition, the former may be made of any
suitable
material such as metal (e.g., aluminium), porcelain, ceramic, plastics, or
composite (e.g.,
metal and plastic).
The terms "product" and "workpiece" are used interchangeably and may also
include any object that can be produced using the methods, apparatus, and
formers of the
invention. Stretchable, elastic products have a variety of uses including,
without limitation,
industrial use such as pipes, seals, membranes sheets, filtering membranes;
food industry
such as breathable stretchable wrappers or coverings for objects including
perishables such
as food; medical industry for medical products such as dressings and bandages;
sanitation,
athletic, and personal hygiene industries such as garments including
protective garments
and undergarments like brassieres, undershorts, socks, or gloves and any other
garment,
undergarment or dressing for veterinary or outdoor use. Other examples of
garments are
described in USSN 10/723,244, filed November 26, 2003, and in USSN 09/744,779,
filed
August 5, 1999.
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The phrase "loose fibers" refers to any suitable loose flocking fiber material
including natural or synthetic materials and may be hydrophilic, hydrophobic,
or a
combination of the two. Hydrophilic fibers include wettable fibers, i.e.,
hydrophobic fibers
that have been treated to render them hydrophilic, absorbent fibers, and
superabsorbent
polymer fibers. Examples of wettable fibers include bicomponent fibers,
polypropylene
fibers, and polyester fibers that have been treated, for example with
surfactants. Example of
wettable fibers are polyester fibers, such as DuPont-Akra Polyester Type 1 1A
BrightTM
commercially available from DuPont Company treated with a surfactant such as
Tween
2OTM commercially available from ICI Americas Inc. Absorbent fibers are
hydrophilic
fibers. Absorbent fibers may comprise rayon fibers, acrylic fibers, nylon
fibers, polyvinyl
alcohol fibers, and fibers of natural or regenerated cellulosics. Example of
absorbent fiber
is rayon fibers. Superabsorbent polymer fibers are hydrophilic fibers that are
swellable and
capable of absorbing greater than about 5 grams per gram (of fiber weight) of
1%, saline
solution. Examples of superabsorbent polymer fibers are polyacrylate fibers,
fibers of
grafted cellulose, and fibers of maleic acid. Examples of superabsorbent
polymer fibers
include OASIS Type l 01 Tm, commercially available from Technical Absorbents
Limited
and CAMELOTTm, commercially available from Camelot, Alberta, Canada. A
preferred
fiber for use in the invention is cotton fibers. Any suitable method for
delivering the loose
fibers so that they may be applied to the surface can be used. For instance,
the loose fibers
can be sprayed or blown onto the surface of the wall as well as
electrostatically and or
pneumatically flocked.
The phrase "product material" comprises suitable stretchable material such as
natural
or synthetic polymers. A natural polymer includes, without limitation, latex
rubber. A
synthetic polymer includes, without limitation, polyurethane. For spraying
purposes,
emulsions, suspensions, or solutions of the product material, e.g., liquid
latex rubber, are
generally used. After spraying the product material, with or without
additional process steps,
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the product material is preferably allowed to dry before it is removed from a
surface. The
drying process may include curing or setting processes, depending on the
choice of product
material. For example, when latex rubber is used as the product material, the
latex rubber
would cure as it dries. In practicing this invention, the preferred product
material is natural
latex rubber, which forms durable, flexible, stretchable, elastic shape-
retaining products.
The term "wall" may refer to a flat or two-dimensional work piece former such
as a
flat conveyor belt or any suitable shaped flat surface to which a product
substantially
conforms. Alternatively, the wall may be a three-dimensional workpiece former
having a
complex shape to which a workpiece substantially conforms. Alternatively, the
wall may be
non-flat, embossed or complex shaped conveyor belt, perforated conveyor belt,
or
combination thereof. The wall may be made of any suitable materials such as
plastic, rubber,
composite (e.g., of metal and plastic or ceramic), ceramics, metal such as
aluminum or
stainless steel.
The present invention provides a surprising and significant improvement over
technologies known in the art by reducing the number of process steps and
entailed costs.
Moreover, the present invention provides a surprisingly effective and
economical way to
produce thin products, sheets and non-woven fabrics that combine different
zones, which
performs differently in the same unified sheet and may be flocked with fibers
at least on one
surface.
In one embodiment of the invention, a method is provided for producing a
stretchable
workpiece, said method comprising the steps of: (a) applying at least one type
of wetting
agent onto a surface of a wall; (b) applying a first layer of at least one
type of loose fibers
onto at least a portion of the surface of the wall to produce at a partially
fiber-coated surface.
The loose fibers are flocked electrostatically or by any other suitable way so
that they hit the
wall substantially perpendicular to its surface; and (c) spraying a liquid
product material of at
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least one type onto the upright standing fibers to form a product material
layer of
predetermined thickness on the fiber-coated surface and produce a stretchable
workpiece,
wherein the product material layer has an inner and outer surface and fibers
are attached to
the inner surface of the product material layer. Another embodiment further
comprises the
step of applying a second layer of loose fibers onto at least a part of the
outer surface of the
product material layer, wherein the product material layer is uncured or
partially uncured. In
another embodiment, the method further comprises the steps oE allowing the
product
material layer to dry; and removing the stretchable workpiece from the
surface.
The preceding methods may further comprise using different machine components
or
different materials in different configurations to produce zones of different
qualities in the
product.
For example, the method for producing a stretchable workpiece can comprise
applying one or more materials on a conveyor or a mold at the same time using
different
machines or compartment or different materials in different layouts so to
produce a
workpiece having two or more zones, wherein at least one zone features a
different material
character than one of the remaining zones. Each material applied may be a
liquid material as
defined above.
In one embodiment at least two different spraying nozzles are used side by
side in
conveyor cross direction to spray material (e.g., liquid material) in
parallel, so that one zone
of the product will comprise lower density then the other part. Each nozzle
may spray the
same material or different materials.
The nozzles may be arranged in a row. For example, as arranged in a row, a
first
nozzle can spray at wider angle than a second nozzle to thicken a section of
the product by
providing thicker elastomeric layer.
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In yet another embodiment, the nozzles are configured to apply at the same
time the
same or different materials in different rates so to control amount of
material sprayed in the
different areas.
In yet another embodiment, the nozzles are configured to apply at the same
time the
same or different materials in different rates so to control amount of
material sprayed in the
different areas and to create areas of different porosity.
Such nozzle arrays may be used, for example, in step (c) as described above to
spray
different product materials. For example, two different materials (different
polymer types)
may be sprayed in two or more zones at the same time. In another example,
different
materials (different colors) may be layered by applying a first material layer
and then
applying a second material layer over the first.
In yet another embodiment, at least two similar nozzles are used to spray
different
polymers, the polymers may differ in: polymer type, formulation or any
property or feature,
such as, but not limited to any mechanical property, viscosity, color, scents
or any other
desired feature.
In one example, tb.e different polymers can be selected independently from
natural
rubber, high modulus natural rubber, low modulus natural rubber, polyurethane,
silicones,
and the like.
In another embodiment, the polymer applied to one of the zones of the product
has a
higher modulus than the polymer applied to at least one other zone. In another
embodiment,
the polymer applied to a first zone of the product has a higher modulus than
the polymer
applied to a second zone.
In yet another embodiment, at least two flocking machines are used to apply
different
types of fibers. Such flocking machines may be used, for example, in step (b),
as described
above, to apply different types of loose fibers, to the different zones of the
product. For
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example, different types of fibers may be applied to the wetting agent in
adjacent zones or
one type of fibers may be applied to the wetting agent (one surface of the
product material
layer), and a second type of flock applied over the second surface of the
product material
layer.
In yet another embodiment, at least two flocking machines are used to apply
different
fibers, the fibers may differ in type, material, length, diameter, color,
odor, compostability,
water retention, hydrophobicity or any other desired feature.
When different flocks are applied in two or more zones, the flock may be
sprayed on
top of the same product material or different product material. In one
embodiment, different
flocks are applied to at least two different zones and the flocks are sprayed
onto the same
product material. In another embodiment, different flocks are applied to at
least two different
zones and each type of flock is sprayed onto a different product material.
In another embodiment, the wetting agent is coated with a first flock, the
first flock is
sprayed onto one or more product materials in one or more zones, and a second
flock is
applied to the outer surface of the product material.
The preceding methods may be used to form unified stretchable non-woven sheets
having two or more zones, wherein at least one zone has a different feature
than one of the
remaining zones.
In certain embodiments, the stretchable non-woven sheets may comprise three or
more zones; or four or more zones; or five or more zones. In other
embodiments, the
stretchable non-woven sheets may comprise two to ten zones; or two to five
zones; or two to
four zones; or two or three zones. In yet other embodiments, the stretchable
non-woven
sheets can have two zones; or three zones; or four zones; or five zones; or as
many zones as
necessary for a given purpose. All zones produced as a unified sheet.
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Each of the zones of the stretchable non-woven sheets can be, for example, but
not
limited to (I) the upper surface and the bottom surface; (2) the right side
and the left side; (3)
a longitudinal, middle portion and the remaining side parts; (4) cross
direction stripes; or any
other desired zone definition or combination thereof.
In one embodiment the product zones each comprise different elastomeric
materials,
such as, but not limited to, natural latex rubber, polyurethane or other
synthetic materials.
The material features of each of the ones may differ in any property or, such
as, but
not limited to, polymer type, formulation, compostability, basis weight,
thickness, porosity,
water or any other liquid permeability, breathability, tear strength,
elongation at break,
refractive force after extension, tensile strength, any other mechanical
property, color, odor,
tactile, or feel.
In another embodiment, the stretchable non-woven sheet comprise different
loose
fibers, at different zones, the fibers may differ in type, material, length,
diameter, color, odor,
compostability, water retention, hydrophobicity or any other desired feature.
In yet another embodiment, the product zones comprise different porosity
levels.
In particular examples, the sheet may comprise a first zone having a first
material and
first flock and a second zone, adjacent to the lust zone, having the first
material and a second
flock. In another example, the shed may comprise a first zone having a first
material and
first flock; a second zone, adjacent to the first zone, having the first
material and a second
flock; and a third zone, adjacent to the first or second zone, having a second
material and the
first flock.
In another example, layers may be sprayed one on top of the other, such that a
sheet
may comprise adjacent zones each where the stacks of applied layers are
different in each
zone. That may get different sandwiches side by side unified on the same
sheet.
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In another example, at least one of the zones of the sheet may comprise a
polymer
having a different modulus from the polymer of the remaining zones. Such
sheets can be
useful for medical usage to provide a bandage having different local pressure
requirements.
In another example, different materials may be using in different zones to
create a
"breathable" area in the sheet; or an improved leak proof area.
In another example, different fibers may be applied to the inner and outer
surfaces of
a sheet, such as providing cotton fibers to the inner surface and artificial
fibers to the outer
surface. Such sheets may be useful, for example, in manufacturing pants or
other garments.
In another example, different zones may be provided with different colored
flock.
Such different colors may be applied in adjacent zones on one surface of the
sheet to produce
a desired design effect; or one color flock may be provided to an inner
surface of the sheet
and another color flock to the outer surface of the sheet.
The methods and products provided herein can be used in the non-woven
industry, as
a sheet of stretchable non-woven fabric to be used as is, or in combination
with other
materials such as, but not limited to, woven and non-woven fabrics, to create
finished ready
to use products such as, but not limited to, diapers, sanitary napkins,
bandages, packaging
means, beddings upholsteries, curtains, apparels, outdoor and military
accessories and the
like.
It will be appreciated by persons skilled in the art of that the present
invention is not
limited by what has been particularly shown and described hereinabove. Rather
the scope of
the present invention includes variations and modification of the various
features described in
the specification and shown in the drawings which may occur to a person of
ordinary skill in
the art upon reading the foregoing description and which are not in the prior
art.
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