Note: Descriptions are shown in the official language in which they were submitted.
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SPECIFICATIONS
FIELD OF THE INVENTION
A composite made by flow-coating powdered plastic onto bond face material.
BACKGROUND OF THE INVENTION
Most thermoplastics do not bond to themselves or to other materials. The
instant
invention uses 'sheet material with raised bonding structures', hereinafter
referred to a
"bond face" to mechanically bond or anchor to thermoplastic. Plastic powder
first flows
into voids and recesses whereafter it is melted and flow-coats all surfaces,
and then cools
hard permanently entrapping the structures thereby anchoring the bond face to
the plastic.
SUMMARY OF THE INVENTION
Powered plastic can be a thermoplastic such as polyethylene, polypropylene,
and
Nylon , and/or a thermoset plastic such as epoxy, polyester, phenolic, all of
which can
be be mixed with glass and/or plastic fibres, fine beads, flock, grit, other
plastic powders,
and the like.
Bond face is generally sheet metal (ductile, machinable) with a plurality of
bonding
structures raised from all or part of one face (single-faced) or from all or
part of both
faces (double-faced). The bonding structures are shaped to entrap a melting
powdered
plastic whereby they anchor in the plastic as it cools hard to create a novel
composite.
One use of the instant invention is to include sheets, strips or patches of
bond face in a
rotational mold such that they become embedded in the plastic of the article
to add
stiffness, strength, heat and bulge resistance, and protection from mechanical
damage. If
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the mold itself is made of bond face the exterior of the article is UV proof
and otherwise
protected from damage. It can receive adhesives and fasteners, magnets,
welding tabs,
brackets etc., enabling other articles to be secured thereto.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective of bond face with bonding structures in the form of
hooks;
Figure 2 is a cross section of a portion of a wall of a rotomold with an
adjacent bond
face, and a layer of plastic encapsulating the bonding structures;
Figure 3 is a perspective of a single tabbed hole bonding structure;
Figure 3a shows a double tabbed hole bonding structure;
Figure 4 is a perspective of a bonding structure comprising a hole with both a
rough,
burred rim/edge and a conical or countersunk rim/edge;
Figure 5 is a perspective of a portion of a reinforcement band of bone ply
with a
transverse curvature and an attachment hole;
Figure 6 is a perspective of the sides (which can all be separate) and the
separate
bottom component of a bond face container (shown unclamped), with all bonding
structures facing inside and onto which plastic will be rotomolded to both
secure
the components together and to seal the resulting composite container. Also
shown
is a corner extension to the bottom component that is left exposed to serve
various
purposes;
Figure 7 is a cross-section of a tubular mold with spiral wound strip of bond
face
inside forming a composite pipe outer surface. Also shown is an uneven layer
of
plastic powder that will be rotomolded to flow-coat the interior. The right
end
portion of the strip is un-wound to show the bonding structures. A heat source
is
identified;
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Figure 8 is a perspective of a composite pipe made from rectangles of bond
face
formed into tubes with edges unjoined;
Figure 9 is a top view of an open rectangular rotomold with reinforcing bands
of bond
face secured to the insides, bonding structures inward, and with removable
fasteners;
Figure 10 shows a rectangular container with spaced bond face bands around the
perimeter having their bonding structures inward. Additional patches of bond
face
can be added wherever required. The holes for securing both are shown;
Figure 11 is an end view of two channels made of bond face that have been
coated
joined with melted plastic powder;
Figure 12 is a side view of bond face with a hooded pock as the bonding
structure;
Figure 13 is a top view of bond face with the pock of Figure 11.
DETAILED DESCRIPTION OF THE INVENTION
In the typical rotational molding of a hollow plastic product such as box C
(Fig 10), a
powdered, non-adhesive polyethylene thermoplastic B (Fig 7) is added via a
removable
cover to a metal mold A (Fig 9) that is made to rotate on all axes such that
the powder
continuously tumbles. As the mold is heated the plastic powder becomes tacky
sticking to
the mold whereon it finally melts and as the temperature rises, becomes more
liquid to
flow-coat the entire interior forming a continuous layer or coating of
plastic. Mold A
continues rotating as it cools whereafter the finished article is easily
removed.
To add stiffness, strength, temperature and damage resistance, reduce the
amount of
plastic required, and to overcome the lack of bondability, the instant
invention uses bond
face 5 inside mold A. Bond face 5 has at least one of its face surfaces
populated with
bonding structures 6.
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Bond face bonding structures can be mass produced from sheet coil stock using
factory-style press machines to drive sets of toothed blades that carve short,
shallow
grooves from which a tongue or burr structure is raised and that remains
strongly
attached. Most ductile-machinable materials such as metals, wood, plastics can
be made
into bond face. Bond face can have a shaped surface on which the bonding
structures are
created with portable tools.
Powdered plastic can be applied to bond face by: sprinkle through sieves and
screens;
spray with flocking-style guns; electrostatic means; hot dipping in a
fluidized bed. Bond
face can be wetted with water or other suitable liquids to hold the powder
from falling
while being handled and/or to provide a functional intermediate layer such as
for
corrosion resistance, noise/vibration reduction, aromatics.
Bonding structures 6 include, but are not limited to, hooks 6a, Figs 3, 3a
tabs 6b, Fig 4
shaped holes 6c and burrs 6e, all of which have an engaging, entrapping,
overhanging,
anchoring, cantilevering shape or design. In additions Figs 4a and 4b show a
bonding
structure 6 made by a curved-tip chisel that impacts into the surface of bond
face 5 at an
angle leaving an angled pock 7a with raised hood 6f.
As the finely powdered plastic tumbles it contacts all cavities, grooves,
slits,
roughness, interstices, flat spaces, under-and overhangs, hoods, of structures
6 and the flat
spaces between. Then as it tackifies the plastic powder coalesces and melts to
flow-coat
an even, continuous, layer submerging bonding structures 6. Importantly,
because the
plastic starts out as a powder coating and then melts into a liquid coating,
there are no
entrapped air bubbles or air pockets with its unwanted moisture, and thermal
related
pressure variations beneath the plastic. If a liquid were applied, unwanted
air would be
trapped in the fine features reducing strength of the composite.
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In this way bond face 5 is mechanically integrated and permanently anchored to
the
plastic B of article C creating a new and novel composite material with unique
and
customizable properties.
Bonding structures 6 engage, embed, lock, key, anchor, in plastic B because of
their
entrapping shape. As such they resist pull-out and relative movement so that
exteriorly
applied loads, forces, and vibrations are widely distributed to reduce
localized failure.
Bonding structures 6 may be produced by a process as taught by the present
inventor in
Canadian Patent #1,330,521 and US Patent #5,376,410 where a dense pattern of
hooked
tongues are raised from a surface of sheet metal creating bond face 5. Toothed
blades are
used to carve short, shallow grooves 7 from which are raised bonding
structures 6, shown
in Fig 1 as hooked tongues or barbs.
In the Figs 5, 6,7, 8, 9, 10 and 11, such anchoring surface structures 6 are
shown for
simplicity as being straight and pin-like, but in fact, each bonding structure
6 must have
an engagingly shaped overhang that would have to be forcefully deformed to
disengage.
Bonding structures 6 can be partially crushed to lower their height as shown
on last 3
structures at right end of Fig 2, requiring less plastic to submerge them.
Fig 1 shows engaging/anchoring bonding structures 6 raised from grooves 7
carved
into the surface of bond face 5 by a toothed blade (i.e. a saw, not shown).
Fig 2 shows a portion of the instant composite material having bond face 5
with its
plain face contacting mold wall A and its bonding structures 6 anchored in
plastic B.
Figs 3 shows a bonding structure as a single ended tab (or chad) 6a, Fig 3b as
a double
ended tab 6b, both resulting from partially punched holes in bond face 5.
Fig 4 shows bonding structure as a hole 6c with a burred edge/rim 6e that
would result
from using a pointed punch to pierce and tear/spread/stretch/rupture open hole
6c in bond
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face 5. Fig 4 also shows hole 6d with a conical/countersunk/formed/shaped
edge/rim 6e
into which plastic can flow and harden to act as a rivet head (head larger
than hole).
Fig 5 shows a band 5a of bond face 5 having structures 6 and one or more of
mounting
hole 9. The band 5b may be curved both longitudinally and traversely (see Fig
9). Band
5a which has its bonding structures 6 facing inward can be secured to mold
wall A by
threaded fastener 11 and nut 12 which engage hole 9 in band 5a and draw it
snug against
the mold wall. After molding fasteners 11,12 are removed.
Fig 6 shows a rectangular skin mold 20 which could be made with 2 or more of
separate pieces of bond face 5 with its bonding structures 6 to the inside.
Double-faced
bond face can also be used. Such a skin mold 20 would be temporarily clamped,
wired,
jammed, notched, pinched, bound together to survive handling and rotomolding.
With
such a mold both non-adhesive thermoplastic and adhesive thermoset powders can
be
used. Thermoset powders will both chemically and mechanically anchor to bond
face 5
for maximum strength and temperature resistance. The exposed plain or
structured
surface of bond face 5 provides UV resistance, adhesive bondability, magnetic-
ness, and
fastener retention. Studs and brackets can be resistance welded or otherwise
fastened to
bond face before molding for additional adaptability. Exterior bonding
structures can be
strongly bonded on.
A thin thermoset layer (structures exposed) can be over-coated with a layer or
ply of
polyethylene thermoplastic for additional benefits such as greater chemical
resistance.
For illustrative purposes only, body 20 in Fig 6 shows only the right two side
of the
interior rotomolded with plastic B and the left two sides and bottom left bare
to show
structures 6. Of course the entire inner surface would in fact be uniformly
and
continuously flow-coated in plastic B.
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Fig 6 also shows another use for the instant invention whereby multiple
components
are filet-joined by the continuous internal plastic layer that also provide a
leak-proofing
and chemical resistance. Extension 8a suggests ways of including extraneous
surfaces
that, for example, can be used for attachment to other surfaces, article, and
electrical
connectivity. The instant invention can also be used to co-join different bond
face metals
and materials such as copper to aluminum to Nylon to wood.
Fig 7 shows a partial cross section of a rotomolded composite pipe 10. Mold A
is a
constrictable slit tube. A flimsy strip of bond face is spirally inserted to
form a loose spiral
walled tube with bonding structures 6 to the interior. Powdered plastic B is
shown as an
uneven layer along the bottom as it would appear before rotational tumbling 4.
Heat 3 is
applied to melt and flow-coat, join, and seal the spiral wall making it
rigid.leak-proof
tube. Right side of Fig 7 shows the last turn of the spiral unwound so bonding
structures 5
are exposed for clarity.
Fig 8 shows how a composite pipe can also be made from one (or more)
rectangular
bond face pieces formed to tubular mold skin(s) 10 with slit(s) 10a, which
sleeve can be
clamped (screw or hose clamps) closed, or multiples clamped together
lengthwise in
retainer-alignment clamp 15 with constriction slit 15a, such that mold skin 10
becomes
the finished pipe's exterior wall when removed from clamp 15.
Fig 9 is top view into a simple rectangular mold A with fitted bands 5s which
are
shown at top and left as being slightly curved so as to be stiff and springy
for a snap fit
against wall of mold A. In some cases such curvature may eliminate the need
for holes 9
and fasteners 11,12. Grooves, notches, ridges, in the mold wall can also be
used to secure
bands 5a.
In Fig 10 the container 20 has a thermoplastic exterior rotomolded in a mold A
in
which bands 5a had been placed. Bands 5a are shown to be flush with the
exterior and
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holes 9 which could be plugged with plastic screws, sealant, or bungs. Fig 10
also shows
bond face patches 8b on left, right, and on a corner, with their bonding
structures 6
anchored in plastic B. Right patch 8b is shown to also have external bonding
structures 6,
that is, double-faced bond face 5.
Fig 11 shows a cross-section end view of two separately formed channel shapes
complementarily arranged for strength. Each has been coated as previously
described.
The two are then brought together with heat from a torch/flame, hot blade, or
hot air
between such that their respective surfaces are melted and quickly brought
into contact so
that they immediately weld together. Alternatively the two channels can be
held together
in a retaining channel 25 (dotted line) of plain metal for rotomolding after
which retainer
25 is removed and the plastic bridges B" (shown on left side only) left on or
cut off.
This description should not be used to limit the scope of the present
invention. Other
examples, features, aspects, embodiments, and advantages of the invention will
become
apparent to those skilled in the art from the following description. It should
therefore be
understood that the inventor contemplates a variety of embodiments that are
not explicitly
disclosed herein.
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