Note: Descriptions are shown in the official language in which they were submitted.
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PRECURSOR LAMINATE AND METHOD FOR FORMING A LAMINATE
FIELD OF THE INVENTION
The present disclosure relates to laminates and composites and methods of
making
same.
BACKGROUND OF THE INVENTION
Laminates and composites are relatively light, stiff and strong compared to
the materials
that make up the constituent layers or lamina.
The term "laminate" generally refers to relatively thin layers of material
bonded together
under heat and pressure to create sheets of laminate from which articles can
be made. Plywood is
common example comprising layers of thin wood bonded together. The result is
very strong
compared to the thin wood constituent layers.
Composites are generally thicker, with skins and cores of different materials.
Skins are
generally a thin, stiff material bonded over a thicker porous core material.
For example, yachts,
aircraft, bridges, and racing cars use composites. Composites can be flat such
as for floors, or
molded into curved shapes such as hulls, wings and chassis.
Construction of current laminates and composites generally requires one or
more
adhesive systems, which are expensive, require considerable time and skill to
use, may comprise
toxic chemicals, and may need sophisticated equipment that requires careful
cleaning.
SUMMARY OF THE INVENTION
A precursor laminate is provided, being formed from a first layer of ductile
material with
a face textured with a plurality of barbs, and a second layer of a heat-
fusible material disposed
on the textured face of the ductile material. When the heat-fusible material
is heated to at least
its melting point, the heat-fusible material at least partially melts so as to
wet and surround a
multiple barbs so that when the heat-fusible material is subsequently cooled
and solidified, the
ductile material and the heat-fusible material are locked together to form a
laminate.
The first layer is preferably a sheet of ductile material, which is preferably
made from
steel. The heat-fusible material is preferably a thermoplastic material, which
may be in sheet
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foim, and the precursor laminate may be formed by pressing the thermoplastic
material onto
the textured face of the sheet of ductile material so that multiple barbs
pierce the thermoplastic
material.
Both the upper and lower faces of the sheet of ductile material may be
textured with
multiple barbs, and the second layer of heat-fusible material may be disposed
on, or affixed to,
the upper face of the sheet of ductile material, with a third layer consisting
of heat-fusible
material disposed on the lower face, so that when the heat-fusible material in
both the second
and third layers is heated to at least the melting point, the heat-fusible
material at least partially
melts so as to wet and surround multiple barbs on each of the faces so that
when the heat-
fusible material is subsequently cooled and solidified, the ductile material
and the heat-fusible
material are locked together to form a laminate.
The heat-fusible material may be (1) fibrous, (2) one or more layers of film,
(3) a
particulate, or (4) pre-preg.
Preferably, the first layer of the precursor laminate is substantially flat.
Some or all of the barbs may be clinched.
The invention also provides a three-layer precursor laminate with first and
second layers,
each being a substantially flat sheet of a ductile material with a face
textured with multiple
barbs. The precursor laminate also has a third layer of heat-fusible material
positioned between
the first and second layers in engagement with the textured face of each of
the first and second
layers so that the heat-fusible material surrounds multiple barbs on both the
first and second
layers. Then, when the heat-fusible material is heated to at least its melting
point, the heat-
fusible material at least partially melts so that it wets and surrounds
multiple barbs. Then, when
the heat-fusible material is subsequently cooled and solidified, the ductile
material and the heat-
fusible material are locked together to form a laminate.
The invention also provides composite panels with at least one panel component
made
from one of the above-described precursor laminates.
The invention also provides a method of forming a laminate. First, a precursor
laminate
comprising a first layer comprising a sheet of a ductile material having a
face textured with a
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plurality of barbs, and a second layer comprising a heat-fusible material
disposed on the
textured face of the sheet of ductile material, is provided. Then the heat-
fusible material is
heated to at least its melting point to cause the heat-fusible material to at
least partially melt so
as to wet and surround a plurality of the barbs. Then, the heat-fusible
material is cooled so that
it solidifies and the ductile material and the heat-fusible material are
locked together to form
the laminate.
The invention also provides a method of forming a laminate from a sheet of a
ductile
material having a face textured with a plurality of barbs. A heat-fusible
material is applied to
the textured face of the sheet of a ductile material. Then the heat-fusible
material is heated to at
least its melting point to cause the heat-fusible material to at least
partially melt so as to wet
and surround a plurality of the barbs. Then, the heat-fusible material is
cooled so that it
solidifies and the ductile material and the heat-fusible material are locked
together to form the
laminate. The heat-fusible material may be in the form of a sheet, and the
heat-fusible material
may be applied to the textured face of the sheet of ductile material by
pressing the sheet of
heat-fusible material against the textured face of the sheet of ductile
material so that multiple
barbs enter, or pierce, the sheet of heat-fusible material.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 shows a cross section of a portion of a sheet of rigid material
having an
illustrative single hooked barb, the result of a cutting tooth plowing a
short, shallow, surface
groove.
Figure la shows a typical row of such barbs on a first material.
Figure 2 shows a cross section of a first material with pointed, piercing
barbs
mechanically engaging a fabric to make an elemental precursor laminate.
Figure 2a shows a first material with barbs on both faces, the upper face
having
retentive, hooked or curved barbs engaging a fabric second material, the lower
face having
pointed, piercing barbs engaging multiple layers of plastic film.
Figure 3 shows an exploded view of one embodiment of a precursor laminate
where outer
upper and lower layers (skins) of second material (fabric) sandwich a central
layer of first
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material barbed on both upper and lower faces.
Figure 3a shows an exploded view of a second embodiment of a precursor
laminate
where the outer skin layers are a first material sandwiching a core layer of
thermoplastic
fabric second material.
Figure 4 shows the layers of Figure 3 mechanically attached together to form a
precursor laminate.
Figure 4a shows the layers of Figure 3a mechanically attached together to form
a
precursor laminate.
Figure 5 shows a truss shaped (flat-bottomed V) core component for a composite
panel,
formed from the precursor laminate shown in Figure 4.
Figure 6 shows an end view of a round-corrugate truss shape of precursor
laminate with
both face surfaces textured and having the second material engaging both
barbed faces.
Figure 7 shows an end view of a square corrugate precursor laminate with both
face
surfaces textured and having the second material engaging both barbed faces.
Figure 8 shows an end view of a Vee corrugate precursor laminate with both
face
surfaces textured and having the second material engaging both barbed faces.
Figure 9 is a skin component for the same composite panel made of precursor
laminate with the barbed, upper face engaging the flexible second material.
Figure 10 shows a loose assembly of the composite panel components where
several truss
members of Figure 5 lie side-by-side on the lower skin of Figure 9. The barb
texturing has been
omitted for clarity, but all internal contacting surfaces are barbed.
Figure 11 shows two outer skin components sandwiching core truss components
and
how a slot and a tongue joint are formed from the flange ends.
Figure 12 shows three composite sandwich panels joined using the tongue and
slot
shown in Figure 11.
Figure 13 shows how the panel can be made from curved skins and reshaped core
trusses.
This can begin as an assembled precursor flat composite panel which is then
curved, reshaping
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all the components together.
Figure 14 shows a cross section of precursor laminate where the first sheet
material has
barbs on both faces and a fabric (or layers of fabric) are engaging the upper
barbs that have been
clinched (bent over), and a thinner textile layer plus a woolly spacer
material are both shown
engaging the barbs of the lower face.
Figure 15 shows a portion of a permanent laminate of the instant construction
method
where two outer layers of first material are joined together by the hardened,
solid second material
between which has been melted so as to flow about their barbs, and then
allowed to cool to a
hard solid thereby locking the barbs together.
Figure 16 shows two precursor laminate layers that can be joined by simply
heating
to the melting point of the second material.
Figure 17 shows a cross section of a composite cylinder where an inner
cylinder of
precursor laminate is wrapped with and outer skin of first material.
Figure 18 shows a side view of two layer precursor laminate brackets bent,
assembled and heated to join the barbs together making a composite bracket.
Figure 19 shows how the composite cylinder of Figure 17 has a layer of first
material
spirally wound on a mandrel with barbs facing outwards, and spirally wrapped
with second
material.
Figure 20 shows the same embodiment with the outer skin of first material
having barbs
facing inwards wrapped over the core second material.
Figure 21 shows multiple layers of precursor laminate with single- and double-
barbed
layers of first material, and including core layers of second material and
where screening serves
to hold the laminates apart to increase overall thickness of the finished
composite panel.
DETAILED DESCRIPTION OF THE INVENTION
A precursor laminate comprises first and second materials where the first
material is
preferably in sheet form and has been processed to have a texture comprising
raised retention
elements, which may be referred to as "barbs". The first material is
preferably a ductile
material in rigid sheet form, which may be sheet metal or plastic, for
example, that can be
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subjected to a tooling process that textures one or both surfaces ("faces") of
the sheet with
barbs. The first material may be steel, aluminum, stainless steel, copper,
polyethylene or nylon,
for example. Steel is particularly preferred as the first material.
The barbs of the first material may have various shapes, densities and
dimensions. For
example, the barb tips may be spike-like for piercing, or hook-like for
retention. Both barbs
types can be clinched, or upset or bent over, to create a head to increase
retentive properties.
This can be done during the texturizing process or afterwards during the
laminating process.
The second material is a heat-fusible solid material such as fabric, powder or
a solid in
liquid suspension that is conformable to the barbs so that it can be placed on
a face of the first
material having barbs so that it surrounds a plurality of the barbs. It is
able to mechanically attach
to, or engage, envelope, be entrapped by, coat, wet, adhere, cling to, be
hooked by, or lock onto,
the barbs such that the first and second materials behave as a single layer
and will not readily
separate under handling. For example, the second material may be a sheet of
thermoplastic
material that is pressed onto a sheet of the textured surface of the first
material so that the barbs
pierce the thermoplastic material to foim a mechanical attachment.
The second material must be heat-fusible so that it can be heated to at least
partly melt the
material and wet the barbs, and then be cooled to cause the material to
solidify so that it is
transformed into a continuous, rigid solid. Upon this transformation, the hard
solid second
material is locked in place by the barbs, bonded to the first material, to
form a laminate. In this
way a precursor laminate of two outer first materials and a centre layer of
second material will
become a permanent laminate when the second material transforms into a hard
solid bonded to
the barbs of the two sheets.
Examples of second materials include, but are not limited to, thermoplastics,
thermoset
pre-pregs of glass or carbon fibre, mixtures and slurries such as cement for
dipping, spraying,
brushing, spreading, and dry powder such as electrostatic spray epoxy. Each
has advantages
with respect to cost, process speed, durability and the like.
Combinations of such materials and folms are also contemplated. For example,
sheet
aluminum and sheet nylon as outer skin layers can have low melt temperature
polyethylene
as a core layer.
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After exposure to appropriate heating and cooling conditions they too will
coalesce/harden
locking the barbed sheets together. For example, powdered glass can be applied
to the facing
barbs of two first material pieces (using well known enamelling techniques) to
create precursor
laminates. Assembled and heated, the glass fuses to itself and to the barbs to
make a one-piece
laminate of steel and glass.
One example of a preferred first material (sheet textured with barbs) is
available from
Nucap Industries of Toronto, Canada under the name NRX. The material may have
one or both
faces textured throughout, or in select locations over one or both faces. Such
material is also
described in International Patent Application Number PCT/CA2013/000500
(publication
number WO/2013/177667).
By barb is meant a raised tongue or hook of material displaced from a groove
to which it
remains firmly attached. In making NRX, multiple rows of short, shallow
grooves are plowed
bi-directionally into the surface of sheet material by toothed blades.
By conforming is meant an aggregate of fibres, films or particles that can
readily contact,
engage and/or coat the barbs by pressing, impaling, brushing, blowing, rubbing
pouring,
spraying, electrostatic application, and the like. Non-rigid heat-fusible
second materials include
both woven and non-woven forms.
By woven is meant textiles such as fabrics, cloth, yarns, weaves, knits,
felts, straps,
belts, webs and the like.
By non-woven is meant forms including film, membrane, wrap, foil, foam, sheet,
sheathing, tissue, overlay, stretch and shrink wrap products, and the like.
Barbs can readily
engage non-wovens in single and multiple layers by piercing.
By particles is meant beads, pellets, powder, grains, dust, flock, chopped
fibre, strands,
wool-like, fluff, fibrefill, and the like, which can be used either in a dry
form or with a liquid
carrier such as a slurry.
By thermoplastic is meant any of a large variety of "plastic" polymers that
liquefy when
heated so as to wet the barbs, and solidify when cooled into a hard solid
locked onto the barbs.
Thermoplastics include polypropylene, polyethylene, polyamide (such as Nylon),
polyester,
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acrylic, PVC, and ABS and the like, and hot melt adhesives which are often a
mixture of
different thermoplastics, waxes and the like.
By pre-preg is meant composite fibres of glass, carbon, etc., woven into a
cloth fabric and
pre-impregnated with liquid resin (such as epoxy) that has been partially
cured to a semisolid. As
such, they are flexible and dry to touch and can be draped, laid, impaled, or
chop-sprayed onto the
barbs. When heated, the resin re-liquefies to wet the barbs and as it cools,
it becomes a hard solid
whereby its fibres and adjacent barbs are locked together into a laminate.
By cements is meant slurries and suspensions that coalesce and harden by
hydration
or by carbon dioxide absorption or the like.
It is contemplated that any of the above may be used in any appropriate
combination to
make a precursor laminate and any resultant laminate and/or composite.
Next are described methods of composite fabrication from precursor laminate.
To make a composite, individual components are cut and/or formed from
precursor
laminate. During such forming, the barbs may be clinched to further secure the
two materials
together. The mechanical attachment provided by the barbs keeps the two
materials together while
handling, forming and assembling the precursor laminate. Alternatively the
first material can be
cut into components to which the second material is then applied to make
precursor laminate
components.
The components are first arranged as per the design to create a "loose"
composite
assembly. Springs, clamps or weights may be needed to maintain intimate
contact. Next the
assembly is processed according to the nature of the second material by
heating and cooling it to
transform it into a hard solid. The entrapped, embedded, enrobed barbs of
adjacent components
are thereby locked together and a one-piece, rigid composite structure is the
result.
In this way a composite is created in a simple, fast, low-cost operation.
By way of example, a composite panel has components made from precursor
laminate of
sheet metal and polypropylene fabric. Its core includes an array of truss-
shaped components of
precursor laminate which are laid side-by-side on a bottom skin of precursor
laminate, after which
an upper skin of precursor laminate is laid on top. Using weights or spring
clamps, the entire
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=
assembly is heated by oven, heat lamps, inductive means, or hot air. Hot air
offers the benefit of
internal and external heating by blowing through the open-ended trusses.
Heating continues until
the thermoplastic polypropylene flows and wets the barbs. After cooling, the
polypropylene
becomes a hard solid which has entombed barbs of adjacent components locking
them together
into a rigid composite panel.
In the case of a particulate thermoplastic, the particulate thermoplastic
(e.g. in powder or
bead form) may be simply poured into the available cavities to fill them and
then heated.
Alternatively the powder may be applied electrostatically (powder coating) to
the individual
components.
As another example, a precursor laminate cylinder may be assembled by forming
an
inner skin on a cylindrical mandrel with barbs facing outwards. This is
wrapped with a
thernioplastic fabric strap which is then wrapped with another layer (skin) of
first material with
the barbs facing inwards. The assembly is removed from the mandrel and heated
to melt the
thermoplastic fabric. When cooled the hard solid thermoplastic with embedded
barbs locks the
skins together into a composite cylinder (tube or pipe).
The instant precursor laminate comprises at least two layers: a sheet of a
first ductile
material 1 having at least one face populated with barbs 3, and a non-rigid
heat-fusible second
material 5 that is situated on at least one textured face of the sheet of
first material. The second
material 2 conformably engages and surrounds the barbs of the first material.
The precursor
laminate can then be used for forming a laminate by heating and cooling the
second material to
cause it to harden around the barbs, thereby causing the second layer to be
retained in
attachment with the first layer. For example a thermoplastic fabric can be
impaled on the barbs
and then melted to wet the barbs. When cooled the two materials become
laminated.
Turning now to the figures, Figure 1 shows a first material 1 with a single
barb 3 rising
up from a groove ploughed in first material 1 by a tool tip. The first
material 1 may be any
machinable or ductile material such as metal or thermoplastic, but not friable
materials such as
glass or concrete and the like. Figure la shows a row of barbs 3 on one face
of a sheet of ductile
material 1. The barbs may be produced in rows so that the barbs in adjacent
rows point in
opposite directions (not shown).
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Figure 2a shows how barbs 3 may have different tip configurations - spike tip
3a and
hook tip 3b, or both. In addition both barb tip types can be rolled, punched
or pressed to deform
the whole barb or the barb tip.
In Figure 2 the second material 5 (e.g. polypropylene fabric) has been impaled
on the
barbs so that the layers are mechanically attached to each other. The fabric's
fibres move aside to
allow the barb's entry resulting in the fabric conformably engaging and
surrounding the barbs to
form a precursor laminate 31 in its most elemental form - one layer of each
material. Figure 2a
shows first material 1 with rows of barbs 3 on both faces and having a fabric-
type second
material 5 engaging the upper barbs 3 and a film-type second material Sc
engaging the lower
barbs and being pierced by barbs of the lower face. The upper barbs 3 have
clinched tips 3b
which act as "heads" to more securely engage and retain the fibres of the
second material 5.
A primary function of the second material 5 is to temporarily attach or join
first materials
to make a precursor laminate which can be handled, formed and assembled. After
assembly, the
second material or materials can be melted to wet and flow onto the barbs
which, when cooled,
transforms the second material layer(s), such as a conformable thermoplastic,
into a hard solid
locking the barbs together. Figure 15 shows two outer layers or skins of first
material 1 whose
barbs have been locked together by the melting and cooling of second material
5a. The layers are
thereby bonded together with each other in a laminate.
Figure 3 shows first and second materials 1, 5 in planar juxtaposition ready
to be
assembled into a precursor laminate 9. Each of the two outer layers of second
material 5 may be a
textile (e.g., fabric or cloth), which engages barbs on the surfaces of first
material 1. Figure 4
shows the resultant precursor laminate 9 after the outer layers have been
heated and solidified.
Figure 3a shows another arrangement where precursor laminate 30 has outer
skins of first
material 1 with inward facing barbs 3 sandwiching a layer of second material
5.
Figure 4a shows the three layer precursor laminate 30 - two outer skin layers
of first
material 1 sandwiching a core layer of second material 5 into which the barbs
are embedded.
Figure 5 shows a precursor flat "V" truss 10 made of precursor laminate 9,
several of
which will become the core layer of a composite panel.
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Figs 6, 7 and 8 show alternate truss profiles, being rounded corrugate 10a,
squared
corrugate 10b, and "V" corrugate 10c, respectively.
Figure 9 shows a skin 31 with first and second materials mated into a
precursor
laminate skin 11 for a composite panel that has an edge folded into a flange
6, without
delamination. Some or all barbs may be clinched during the folding operation.
Figure 10 shows the assembly 12 of truss cores 10 laid on a precursor laminate
skin 11.
End trusses 10d are different in that they have a right angle bend that will
become a panel
connector. Although burrs 3 are labeled where they would be, they have been
omitted for
clarity.
Figure 11 shows the final assembly of the truss-cored composite panel 12 with
skins 11
and multiple truss cores 10. Flanges 6 are shown adjacent truss component 10d
which has a right
angle facing the outside. This enables a narrow gap to the shin flange to be
created during
assembly.
The assembled panel 12 is then heated to a temperature sufficiently high to
modify the
second material 5 so that it wets-out adjacent barbs and adjacent surfaces
(Figure 15). After
cooling, the second material 5 coalesces into a hard solid 5a (Figure 15)
locking the barbs of
panel components 10, 11 together into a one piece, novel composite panel 21.
In Figure 12 three separate panels 12 are shown being joined by means of their
end
flanges 6 and gaps 8.
In Figure 13 is shown a curved panel 14, a variation where the precursor
laminate 9 is
curved. Such material may be used, for example, as a roof.
Figure 14 shows how a loose fibre 5b engages barbs 3 on bottom face of first
material 1 and how it can be combined with fabric 5 as a two-layer layer.
Fibre 5b may be
thermoplastic or it may be glass, carbon or other non-melting additive added
to alter the physical
properties of the instant laminate by providing known tensile strength to the
matrix in which it
becomes embedded when second material 5 melts and coalesces on cooling.
It should be understood that the above-described embodiments of the present
invention,
are only examples of implementations, merely set forth for a clear
understanding of the principles
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of the invention. Many variations and modifications may be made to the above-
described
embodiment(s) of the invention as will be evident to those skilled in the art.
Where, in this document, a list of one or more items is prefaced by the
expression "such
as" or "including", is followed by the abbreviation "etc.", or is prefaced or
followed by the
expression "for example", or "e.g.", this is done to expressly convey and
emphasize that the list
is not exhaustive, irrespective of the length of the list. The absence of such
an expression, or
another similar expression, is in no way intended to imply that a list is
exhaustive. Unless
otherwise expressly stated or clearly implied, such lists shall be read to
include all comparable or
equivalent variations of the listed item(s), and alternatives to the item(s),
in the list that a skilled
person would understand would be suitable for the purpose that the one or more
items are listed.
The words "comprises" and "comprising", when used in this specification and
the claims,
are used to specify the presence of the recited elements, and do not preclude,
nor imply the
necessity for, the presence or addition of one or more other elements.
The scope of the claims that follow is not limited by the embodiments set
forth in the
description. The claims should be given the broadest purposive construction
consistent
with the description as a whole.
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