CA3028658A1 - A composite made by flow-coating powdered plastic onto bond face material - Google Patents

Abstract

A composite of loose powdered plastic flow-coated onto the surface of a bond face material whose surface has multiple raised engaging structures. Bond face can be included in rotational molds to add desirable characteristics to the molded plastic article.
Bond faced components of metal, plastic, and wood, can be joined and co-joined with the plastic coating. Such constructions can include plies of glass- and other fabrics. The powdered plastic can include additives such as fibres, beads, grits and the like.

Description

, 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 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;

2 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.

3 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.

4 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 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.

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 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.

Claims (4)

1. A composite comprising bond face material flow-coated with plastic.

2. An article at least partially comprising the composite of Claim 1.

3. An article comprising at least two components made of bond face and joined by flow-coating.

4. An article comprising at least two components made of the composite of Claim 1 and joined by welding.