Pre manufactured structural panel consisting of a flame retardant external crust and an aeroboard core fabricated from laminations of uncompressed cardboard, impregnated by resin solutions recovered from post consumer thermoplastics
Kind Code:

A premanufactured structural composite panel consisting of a cardboard core impregnated with resin solutions recovered from post consumer thermoplastics, and an impact resistant and flame resistant crust formed from Portland cement mortar or polymer cements formulated from said recovered resin solutions, particulates and fibres or fabric and decorated using coatings formulated from said recovered resin solutions. The flame retardant treatment includes ammonium, boron, phosphorous compounds for the cardboard and recovered resin solutions that demonstrate a flame retardant character.

Cole, Jefferson Anthony (Sangre Grande, TT)
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International Classes:
B32B3/28; E04B1/12; E04C2/34; (IPC1-7): E04C2/00; E04C2/54
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Primary Examiner:
Attorney, Agent or Firm:
Jefferson A. Cole (Brooklyn, NY, US)

What is claimed is

1. A prefabricated panel designed to fit together with other panels of the same design and conventional building materials to form walls, floors, ceilings, roofs insulation slabs, partitions and furniture of buildings comprising an inner aerated core made from laminations of cardboard (corrugated container board) that have been impregnated superficially and internally by resin/solutions recovered from post consumer thermoplastics as the impregnant. Said lamination is achieved by the application of adhesives recovered from post consumer thermoplastics and contact pressure alone which allows the sustained columnar structure of the corrugated cardboard elements.

2. A prefabricated panel as claimed in claim (1) wherein one or more additional elements selected from the group consisting of electrical, plumbing and attachment components are inserted in said core during the lamination process by cut-outs and lateral displacement of cardboard elements.

3. Additional elements as claimed in claim (2) may have their tolerances reduced by the application of polymer cements containing particulates and fibres.

4. A prefabricated panel as claimed in claim (1) wherein one or more additional ingredients selected from a group consisting of insecticides, waterproofing agents, anti-fungal agents and flame retardants are added to the impregnant, laminating adhesive or the crust forming polymer cement mortar.

5. A prefabricated panel as claimed in claim (1) wherein the core may be made receptive to the attachment of Portland cement mortar by the attachment of an interface consisting of fabric gauze, fibres, fibre mats adhered to the external cardboard core surface.

6. A prefabricated panel as claimed in claim (5) wherein the outer core surfaces are thickened by lamination of resin-impregnated paper or fabric as a surface finish or to increase surface impact resistance.

7. A prefabricated panel as claimed in claim (6) wherein the surface is painted using cementitious coatings formulated from resin solutions recovered from post consumer thermoplastics, pigments, particulates and plasticisers.

8. A prefabricated panel as claimed in claim (1) wherein wire mesh including B.R.C may be fastened to the outer faces of the cardboard core using connecting stands of wire inserted through perforations in the cardboard core; said wire mesh receives and strengthens Portland cement mortar crusts; cardboard cores with their attached steel mesh may be transported to the construction site and fixed before lay-up of the Portland cement mortar.

9. A prefabricated panel as claimed in claim (1) wherein a single ply of steel mesh together with a polymer cement mortar forms the innermost layer of the cardboard core by its entrapment between two sections possessing half the dimensional thickness of the prospective panel core.

10. A prefabricated panel as claimed in claim (1) wherein the outer crust consists of polymer based mortars formulated from resin solutions recovered from post consumer thermoplastics and micronised particulates, fibres and aggregates.

11. A prefabricated panel as claimed in claim (9) wherein the external crust are formed using methods described in claim (10) mutually excluding methods described in claim (8).

12. A prefabricated panel as claimed in claim (1) wherein the spaces for doors, archways windows, air-condition, recess for roof rafters units, metal inserts, exhaust fans are excluded during lamination or may be cut out after lamination.

13. A prefabricated panel as claimed in claim (1) wherein the columnar spaces created by the corrugated elements within the cardboard sheetstock are inspected for openness and sliced transverse to the column axis using a sharp cutting instrument to facilitate internal distribution of the post consumer thermoplastic resin solution, evaporation of the solvent and the circulation of hot air to accelerate solvent evaporation.

14. A prefabricated panel as claimed in claim (1) wherein the cardboard sheetstock as prepared in claim (13) are stacked and clamped superposed with the corrugated columnar spaces oriented vertically thereby facilitating the introduction and dissemination of the thermoplastic resin solution impregnant by internal drenching, gravity flow and capillary action.

15. A prefabricated panel as claimed in claim (14) wherein drenching is continued until excess resin drains out at the lower end of the vertically oriented cardboard stack

16. A prefabricated panel as claimed in claim (15) wherein hot air is forced through the columnar airspaces of the impregnated cardboard sheetstock to accelerate solvent evaporation and the formation ofa stiff fibre polymer matrix.

17. A prefabricated panel as claimed in claim (15) wherein said processes are repeated until a threshold polymer saturation is achieved characterized by optical changes, improved impact strength without columnar space occlusion.

18. A prefabricated panel as claimed in claim (15) wherein resin viscosity is adjusted based on the assessed porousity of the cardboard sheetstock, the polymer species present in the impregnant and the diameter of the columnar spaces.

19. A prefabricated panel as claimed in claim (1) wherein the labyrinth of interconnected microspores and longitudinal columns present in the cardboard sheetstock provides a template for the expansion of the polymer impregnant.

20. A prefabricated panel as claimed in claim (1) wherein the longitudinal columnar spaces of fully cured panels may be partially filled with a polymer cement to enhance load bearing characteristics and the receipt of surface amendments.

21. A prefabricated panel as claimed in claim (1) wherein bolts are introduced at strategic points on the superficial aspect to secure metal inserts and inhibit delamination stresses.

22. A prefabricated panel as claimed in claim (1) wherein ribs are attached at intervals to function as rafters or purlins for roof construction.

23. A prefabricated panel as claimed in claim (22) wherein a steel mesh is incorporated in both rafter elements and the main panel body by methods described in claim (9).

24. A prefabricated panel as claimed in claim (1) wherein joining may be facilitated by lap joints, interdigitation of mated edges and the welding of metal abutments that may extend from the fastened metal inserts ofjuxtaposed panels.

25. A prefabricated panel as claimed in claim (1) wherein the resin solutions and adhesives are selected individually or severally from a group of post consumer thermoplastics that include polystyrene foam, polystyrene (unexpanded), polymethyl methacrylate, celulosics, polyvinyl chloride, polyurethane, asphalt, flame retardant high impact polystyrene (FR) HIPS, (FR) ABS (Acrilonitrile butadiene styrene), (FR) Acrilonitrile Styrene Acriloniltrile (ASA), Flame Resistant (PC/ABS) (Polycarbonate/ABS) and Ignition resistant, polycarbonate ABS (IRPC/ABS).

26. A prefabricated panel as claimed in claim (1) wherein solvents, dispersants and swelling agents are selected individually or in combination from a group comprising, toluene, acetone, methylethyl ketone (M.E.K), methylene chloride, methylene trichloride, sulfolane, ethylene glycol, amyl acetate, propylene glycol, methanol, diesoline, propylene carbonate, methylene dichloride, dioxan, decalin, tetralin, meta cresol, tetra chlorethane, orthochlorphenol, trichlorphenol, ethylene-m-chloraniline, 3-sulphonolanyl ethyl ether, phenol, nitromethane and kerosene.

27. A method for commercial recovery of resin solution from polystyrene foam using apparatus called the foam digester comprising: (a) A large capacity digestion tank into which polystyrene foam is fed from a stock pile. (b) A solvent distribution system made from perforated tubes mounted above the hopper which directs a solvent shower over the polystyrene charge in the digestion tank. (c) A funnel-shaped lower floor in the digestion tank collects the resin solution, which accumulates with increasing viscosity after its downward flow and dissolution through the resident polystyrene foam charge. (d) A pump which delivers the solvent to the distribution system. (e) The solvent flow rate is adjusted by control valves present on the solvent supply line and the solvent return line. (f) Collected resin solution is removed periodically. (g) A vertical reciprocating hopper recharges the polystyrene foam charge within the digestion chamber at metered intervals assessed by the operator. (h) A hinged recoil able inner basket which is released when the vertical reciprocating hopper is at rest in the lowered position thereby facilitating loading. (i) An extended side wall which retains the polystyrene foam feed stock from escaping from the open side of the recoilable inner basket of the reciprocating hopper. (j) The polystyrene foam feedstock slides into the digestion chamber along the slanting floor of the reciprocating hopper when it becomes aligned with the trap door opening of the digestion chamber during the upper extremity of its vertical travel. (k) The reciprocating vertical locus of travel of the reciprocating hopper is facilitated by linkages to a drive sprocket, chain, a concentric slave sprocket and gear assembly and a mated serrated bar.

28. The recovery of resin solutions from Postconsumer thermoplastics (PCTP) by simple immersion in a potent solvent bath

29. The method of claim 28 wherein the PCTP material is coarsely pulverized to achieve volume reduction before simple immersion.

30. The method of claim 28 wherein the solvent bath is charged with the addition 20% styrene solution by volume to promote homogenous dispersion of highly cohesive PCTP feedstock solutes

31. The methods of claim 30 wherein an inert, micronised mineral particle forms 20% by volume suspended in the solvent to promote mechanical dispersion of highly cohesive PCTP solute feedstock.

32. The method of claim 31 wherein intermittent agitation is applied using a rotary or oscillating device.

33. The method of claim 31 wherein a dispersion of wax, 10% by volume is added to the solvent bath to plasticise the dissolved PCTP feedstock solute.

34. The method of claim 31 wherein dispersion is promoted using a rotary device to accelerate collision between the surface of PCTP feedstock and swirling inert mineral particles.

35. The method of claim 10 wherein the formulation of adhesives, binders, coatings and cements that specifically exploits the flame retardant and ignition resistant products recovered from solutions of post consumer: P.V.C, FRHIPS, FR/ABS, PC/ABS, IR/HIPS, PVC/ABS

36. The method of claim 10 wherein the solvent is selected uniquely or severally in cocktails from Schedule of Solvents and Corresponding PCTP presented below. 3
SpeciesSourcesSolvents 1
High impact Poly-Refrigerator door liners,Acetone Methyl Ethyl
styrene HIPStelevision cabinetsKetone (MEK) Solvent
Polymelthyl-Television cabinets, toysAcetone, MEK solvent
metacrylatesigns, refrigerator
accessories, auto mobile
Polyvinyl Chlo-pipes, floor tiles,Sulfolane dioxan
ridecorrugators monitorsperchlorethylene
cabinets floornitromethane, 3 -
ethyl ether, m -
Polyethylenebottles, tanks, bags,Decalin, tetralin
tri chlor
phenol, meta-cresol,
Flame RetardantComputer monitors, faxAcetone, MEK solvent,
HIPSmachines, photocopierstoluene
Polystyrene foamInsulation, packagingToluene, Acetone
Flame retardantComputer monitorAcetone
Acrilonitrile Buta-housingMEK solvent
diene styrenemethylene chlorine
Flame resistantComputer monitorAcetone MEK solvent
polycarbonate/ABShousings, fax machine,
(FR PC/ABS)photocopiers
Ignition ResistantComputer monitor
Acriloritrile-housings, fax machine,
Ignition ResistantComputer monitor
High Impacthousings, fax machine,
FR PC/ABSComputer monitor
housings, fax machine,
PVC/ABSComputer monitorSulfolane Acetone
housings, fax machine,MEK solvent

37. The method of claim (28) wherein purposeful and strategic fragmentation and volume reduction of complex post consumer thermoplastic products by dismemberment into sheets and non-sheet fragments prior to their immersion into solvent baths.

38. The method of claim (28) wherein thermoplastic sheet fragments are stacked using non-sheet fragments as spacers to facilitate liberal surface contact with the investing solvent bath.

39. The method of claim (28) wherein the stacked and spaced thermoplastic sheets are suspended in a solvent bath using wire or cordage.

40. The method of claim (28) wherein solvent agitation is achieved by air bubbles delivered through perforations the at dorsal aspect of an air pressure hose located at the floor of the immersion vat.

41. The method of claim (14) wherein the cardboard stack is immersed in the impregnant or alternatively the impregnant is forced into the columnar spaces under hydrodynanic pressure.



[0001] 1

References Cited
DateYrU.S. Pat. No.Author
April1895536,993J. T. Allen
Aug. 1719231,541,163Minache
Jan. 2419582,839,312H. Serliner
Jan. 719925,078,937Ee/a
Aug.19925,140,086Hunter et al
Dec.19965,580,922Park et al
Mar. 2419985,729,936Maxwell J.
Mar. 919995,880,243Park et al
Nov. 620016,313,423Sommer et al
Jan. 120026,335,376Allen III et al


[0002] The present invention relates to by products of post consumer cardboard, paper and thermoplastics and in particular prefabricated panels formed by the impregnation and lamination of cardboard sheets using resin solutions recovered from post consumer thermoplastics.

[0003] The airspaces created by the corrugated sections of cardboard (corrugated container board) and the micro porosity of the paper present in cardboard are critical structural characteristics that facilitates the impregnation and curing of the panels respectively.

[0004] The internal columnar spaces in the cardboard sheet stock are drenched by the gravity flow of resin solution when said spaces are oriented vertically. Surface adhesive application and lamination of dried internally drenched cardboard sheet stock forms panels with panel cores of appropriate thickness (called aeroboard). The curing of the resin solution is achieved by the forced circulation of hot air through the columnar air spaces present in the cardboard sheet stock. Drying may be done in kilns or directed hot air streams under covered plastic sheets.

[0005] The quest for alternative uses for bulky wastes has led to a range of processes for recycling and reuse of paper plastics and paper products. A large number of outcomes are directed to the fabrication of building insulation materials in shredded molded and compressed forms. The bulk of these wastes continue to be burned or dumped in landfills.

[0006] Various methods of prefabrication of building panels have been developed. U.S. Pat. No. 536,993 to J. T. Allen issued April 1895 describes a method of forming panels from chips of stnre or clay embedded in a plastic material wherein interstices between the chips are partially filled with sand. U.S. Pat. No. 2,839,312 to H. Serliner issued Jun. 24, 1958 claims a structural panel consisting of high strength concrete on both sides of a metal framework. The space between the two high strength layers of concrete is filled with a lightweight low strength concrete. U.S. Pat. No. 5,078,937 to Eela issued Jan. 7, 1992 claimed a method to form a slab like product from fibrous materials mixed in concrete.

[0007] U.S. Pat. No. 1,541,165 to Minache issued Aug. 17, 1923 describes a thin, three layered—load-bearing wallboard composite.

[0008] A number of patents have been directed at the production of insulation material U.S. Pat. Nos. 4,184,311 and 4,300,322 detail molding and shredding and laminating techniques. Methods also employed various combinations of injecting, spraying adhesion and curing processes. The formulation of slurries of shredded waste material is also commonly exploited.

[0009] The pervasive use of high temperatures and pressures in the processing of bulky wastes into remanufactured products is frequently described within the art. These conditions seek to achieve both impregnation, uniformity and heat catalyzed curing. Hunter in U.S. Pat. No. 5,008,359 prescribed temperatures above 150 degree C. and pressures greater than 3000 K Pa in the processing of cellulosic substrates with isocyanate impregnants. Hunter et al in U.S. Pat. No. 5,140,086 prescribed the use of compatible organic solvents for the promotion of uniform dispersion of the impregnant. The prohibitive costs of presses for these high temperature and compression operations however would contribute significantly to increase their production costs.

[0010] Attempts were made by Wallick in U.S. Pat. Nos. 5,292,391 and 5,332,458 described a spray technique using PMDI products to enhance the strength of the corrugated medium of container board prior to the lamination of external facings. Clearly the prior art appreciated the problem of impregnating a multi-ply laminate after assembly. Park et al in U.S. Pat. No. 5,580,922 attempted to overcome the problem of deep cross-section cure by the addition of a catalyst system. J. Maxwell in U.S. Pat. No. 5,729,936 issued in Mar. 24, 1998 employed removable rods that provided conduits for the drying of the compressed slurry.

[0011] The problem of flame retardancy has been confronted in many patents related to building panels. Some include U.S. Pat. Nos. 5,729,936; 5,715,637; 6,368,529 and 5,880,243. The last mentioned by Park et al in U.S. Pat. 5,880,243 issued Mar. 9, 1999 detailed trials were described in the quest of flame retardancy in lignocellulose composites. Herein the virtues of mono-ammonium phosphate, diammonium phosphate, halogenated phosphates, borates aluminum trihydrate and antimony oxide were explored. Commercially prepared (brand name) flame retardants were also documented. The volume of plastics in the solid waste is approximately 25%. This represents 90% of the total volume of plastics actually produced and can be regarded as a considerable drain on the non-renewable resource base, mankind, governments and the environment. The recycling of thermoplastics has been integral to the industry from its inception. Early recycling involved the fragmentation and reuse of factory generated scraps. Later techniques involved heating, compaction, shredding and granulation. These methods extended the range of products developed from recycled post-consumer thermoplastics. New products included fabrics, carpets, household durables and packaging. Lately research has been aimed at efficient methods of identifying, sorting and separation of post consumer thermoplastics. Sommer et al in U.S. Pat. No. 6,313,423 issued Nov. 6 2001, applied Raman Emission Spectroscopy to identify and sort Post consumer thermoplastics. Allen III et al in U.S. Pat. No. 6,335,376 issued Jan. T 2002, describes a method of separation of post consumer thermoplastics by a process of density differential alteration. What is not disclosed in the prior art is the non-destructive remanufacture of panels from cardboard as well as the application of resin solutions recovered from post consumer thermoplastics as the impregnant for the fabrication and decoration of said panels. The methods disclosed in this invention therefore regards the cardboard sheetstock as an intermediate per form whose characteristics are exploited in the impregnation drying and lamination stages of panel fabrication


[0012] The invention herein described is directed to new and useful light weight lignocellulosic fibre-polymer sheeted products. The sheeted products may be fabricated to form partitions walls roof, ceiling, insulation, floors and furniture of domestic (permanent and relocatable) recreational, agricultural, marine and commercial buildings Cardboard sheet stock (post consumer or ex-factory) are inspected for openness of those spaces formed by their corrugated interior. Where edges are damaged these are cut with a sharp instrument to expose the entrance to the interior columnar spaces. Constrictions in the columns may also be removed by cutting away sections along which folding was done to form boxes. Dents and fractured sections may also be similarly trimmed to expose the interior columnar spaces. Sections breached by staples may also be removed, since they will obstruct the drenching/impregnation process. Cardboard sheet stock so prepared are neatly stacked, clamped and oriented such that the columnar spaces are oriented in the vertical plane. Resin solution recovered from post consumer thermoplastic is then poured into the vertically oriented columnar spaces until the excess flows out at the lower openings of said columnar spaces. The stack is then laid horizontally and allowed to dry. Drying may be achieved by wheeling into a kiln, or wrapping in a plastic or leatherette sheet under which hot air is circulated. Microwave and RF radiation are also feasible methods. The addition of a compatible exothermic catalyst system to the resin solution immediately prior to drenching is also a feasible drying technique. Other additives may be added to the drenching resin solution complex including insecticides, flame retardants, water proofing agents and wood preservatives. Where cardboard sheet stock demonstrates large bore columnar spaces, lamination and lay-up may be done prior to drench/impregnation. The viscosity of the resin solution is adjusted to the diameter of the columnar spaces in the cardboard stock prepared for impregnation. An adequate drench does not result in saturation of the surface layers of the cardboard sheet stock and they continue to be separable by gentle delamination efforts after drying. Repeated drenching may be done to achieve a threshold impregnation. These successive drenches, however, must not clog the columnar spaces.

[0013] The clamping technique must be such that the individual cardboard sheets are tightly packed prevention resin flows about their external surfaces. The dried impregnated cardboard sheet stock is then laid up to the desired form and thickness. This is done by roller application of adhesive followed bv superposing. Where impregnated sheets vary in size they may be staggered to prevent joint alignment. Plies should be of uniformed thickness, cutouts may be done at this stage for doors, windows, roof rafters, fastening metal inserts, plumbing, electrical, heating and margins for mated joints. The completed lay-up is clamped then dried by directing hot air through the open columnar spaces as described above. Clamping must achieve contact pressure alone. This can be still considerably higher than that applied during post impregnation drying due to the increased compressive loading capability of the impregnated corrugated units within. At threshold production volumes, vacuum evaporation can be used to achieve solvent condensation and recovery. Scale economies may be feasible during the drying process using such solvent condensation techniques. Panels destined for use as high load bearing units are encased in wire mesh of appropriate density. The wire mesh is secured using twisted wire connected to either side through drilled holes. Such panels are transported positioned and finished using portland cement mortar. Delamination guards are installed by deploying nuts and bolts with washers of appropriate diameters over the exposed superficial face of the cured panel but before lay up of the external crust. Nuts and bolts are introduced to secure metal inserts and partially function as delamination guards simultaneously.

[0014] Panels destined for low and moderate load bearing applications may be surface finished by a range of optional treatments. These options are arranged below in ascending order of sophistication.

[0015] 1. The outer surfaces are strengthened using several laminations of paper. These panels may then be painted using, decorative coating formulated from resin solutions recovered from post consumer thermoplastics.

[0016] 2. The outer surfaces are laminated with a fabric gauze of appropriate texture and porosity using an adhesive formulated using resin solutions recovered from post consumer thermoplastics.

[0017] 3. Coarse fabric gauze is laid up on the outer surfaces using an adhesive formulated from resins recovered from post consumer thermoplastics. A 4 mm layer of Portland cement mortar is applied to smoothness. In this method delamination guards may be located after the coarse fabric gauze has been laid up to also assist in the securing of the gauze itself

[0018] 4. The cured panel may also be finished using a polymeric mortar consisting of resin solution recovered from post consumer thermoplastics chopped fibre, micronized mineral particles and small particle building aggregates. When partly cured these lay-ups may be planed using a fresh mix of easy flowing polymeric cement mortar. Planing may be done using hand float, draw board, guided edges or rotary devices. Where indicated flame retardants may be included in this polymeric cement mortar.

[0019] 5. The cured panel may also be finished after securing a fibre mat to the outer surfaces using polymeric adhesives as described above. Delaminating guards may then be deployed strategically. Upon drying 8 mm of Portland cement mortar is applied to smoothness.

[0020] Dried panels destined for use as roof panels require further variations. These are laid up to half of their final thickness. A layer of wire mesh of an appropriate density is then laid up along with a slick of polymeric cement sufficient to slightly cover the wire mesh. The other plies are laid up and cured. Alternatively the other half of the panel may be superposed upon the wire mesh/polymeric cement secondary core. Upon curing ribs are attached corresponding to rafters and purlins of conventional roofing. The interval used between these ribs must match recesses left on the relevant upright wall panels. These ribs are formed by cutting off suitably sized (5-8 mm)×(16-21 m)×L from cured panels. The rafter sections are then secured to the roof panel by polymeric adhesive cements and fabric gauze. Dedicated purlin elements may be fabricated with an internal reinforcement of wire mesh of appropriate density. As described above a slick of polymeric cement must also accompany the reinforcing wire mesh.

[0021] The exposed surface of the roof panel is thickened with two to three laminations of paper and polymeric adhesive. Alternatively a fabric gauze of suitable density and weatherability may be applied and secured with a polymeric adhesive. Voids created at the surface where sheets are joined may be solidified using a polymeric cement mortar or putty. Upon drying a fabric gauze is also secured to said exposed surface using a polymeric adhesive. A pigmented decorative coating is applied. Said decorative coating is formulated from resin solution formulated from post consumer thermoplastics.

[0022] The dry cardboard panel may also be used in the fabrication of furniture. In this application it can replace some classes of compressed composite boards in countertops, troughs, table tops, bed heads, ceilings, sidings and awnings. Where high stress joints are contemplated the aeroboard may be strengthened locally by injection of quick setting polymer cements into the columnar air spaces and cutouts around inserts. Dimensional stability may also be enhanced by attachment to lengths of timber. Such furniture can be surfaced finished using veneers coatings and laminations.

[0023] The recovery of resin solutions from post consumer thermoplastics has been the source of binders for the fabrication of panels in this invention. In so doing an attempt is made to utilize two classes of bulky wastes simultaneously into new and useful remanufactured products. Of the polymer species recovered polystyrene foam is the most abundant; and the most soluble. For commercial recovery of polystyrene solution from polystyrene foam (expanded polystyrene) the peculiarities of its structure had to be observed and exploited. Upon exposure to potent organic solvents polystyrene foam dissolves rapidly. If the foam specimens are added to the solvent in a container rapid dissolution begins. The low specific gravity of the polystyrene foam causes flotation at the surface of the solvent. The dissolution slows down progressively as the solution at the base of the floating foam mass thickens. The specific gravity of the floating gel is reduced by the entrapment of pockets of liberated blowing agent from the collapsing closed cells of polystyrene foam. The increasingly viscous gel becomes a mechanical barrier between relatively pure and unsaturated solvent below it and the intact mass of expanded foam above it (the viscous gel). These events militate against efficient application of immersion as an effective and viable method for commercial recovery of resin solution from post consumer polystyrene foam.

[0024] In this invention the foam digester is applied to overcome the difficulties outlined above. The key element in the superior productivity of the foam digester is the dispersing of the solvent from locations above the charge of polystyrene foam specimens. The dispersion of the solvent from above the foam specimens allows the escape of the blowing agent from the collapsing closed cells. These pockets of blowing agent escape directly through the surface of films of highly unsaturated resin solution flowing over the unstable surface of dissolving foam specimens. The moving film of solution does not allow strong surface tension to be achieved due to the effervescence of migrating pockets of blowing agent. Pockets of blowing agents are also liberated by abandonment due to the downward movement of the solution. The effervescence of the blowing agent also lubricates the downward flow of the resin solution. Further, continuous dilution of the resin solution so formed allows continued solvent attack on the closed cells at the surface of intact polystyrene foam specimens. Said dilution results from the continuing release of solvent from solvent dispenser located above the polystyrene charge.

[0025] Polystyrene foam specimens at the lower regions of the charge also benefit from good wetting out and surface cling achieved by the increasingly viscous solution in its downward flow. Penetration is also achieved by the upward displacement of the blowing agent and the entrapment of solvent in the freshly opened empty cells.

[0026] The control valve supplying the dispersion system must therefore be adjusted to allow a final solution that can flow readily into collection drums. Accumulated solution is drained off periodically. Solvent flow adjustments are influenced by the foam density, the solvent potency and the height of the polystyrene foam charge in the digestion chamber.

[0027] Solvent action in the foam digester is therefore rapid and productive. Any solvent pump in use is adjusted with the help of a valve-controlled return line. Solvent delivery rate is a function of frictional losses based on column height, initial pump pressure, tank-to-pump frictional losses and the pressure deflation created by setting variations at the two control valves. Solvent delivery at the dispenser is the residual pressure occasioned by these adjustments.

[0028] The dissolution of other plastics is not as rapid as obtains in polystyrene foam. The method for recovering other species therefore involves immersion in solution vats containing solvents of assessed potency. The table below matches various polymer species to their respective solvents. 2

PolystyreneRefrigerator liners,Toluene, Acetone
television and radio
Polymethyl-Television cabinets,Acetone, MEK (Methyl
metacrylatetoys, signs, refrig-Ethyl Ketone) solvent
erator accessories,
automobile accessories
Polyvinyl Chlo-Pipes, floor tiles,Acetone, MEK (Methyl
ridefloor covering,Ethyl Ketone) solvent,
computer monitor,sulfolane, dioxan,
cabinets, domesticperchlor ethylene,
plastic sheetingnitro methane, 3-
sulphonolanyl, ethyl
ether, m-chloraniline
PolyethyleneBottles, tanks, bags,Decalin, tetralin,
PolyestersFabricsPhenol Meta-cresol
orthochlor phenol
Flame ResistantComputer housing faxAcetane, MEK (Methyl
High Impactmachines, photocopiers,Ethyl Ketone) solvent
Polystyrene foamInsulation, packagingToluene
Acrilonitrile Buta-Computer housings,MEK solvent, acetane,
dienerefrigerator linersmethylene, chloride
Styrene (ABS)
Acrilonitrile Sty-Computer cases, faxAcetone, MEK solvent
rene, Acrilonitrilemachines, photocopiers,
(ASA) copolymer,housings
ignition resistance
Flame resistantComputer housings forAcetone, MEK solvent
polycarbonatemachines housings,
(ABS) FRphotocopier housing

[0029] The resin solutions recovered from these consumer thermoplastic wastes are used in the preparation of adhesives, polymeric cements, sealants and pigmented coatings for the prefabricated panels. Resin solutions recovered from PVC wastes and the cases of computer monitors IR and FR (ABS, ASA, PC/ABS) confer flame retardancy to preparations of which they are a component and are particularly valued for this purpose. These flame retardant components are used in conjunction with other flame retardants such as boron, ammonium, phosphates and halogenated compounds mentioned earlier.

[0030] Water soluble flame retardants can be applied to the cardboard sheet stock before impregnation as a drench. Stacking, drenching and drying may be done similar to the methods described for resin solution impregnatioli. Water insoluble flame retardants are dispersed into impregnating solution, adhesives and polymeric cements used in the fabrication of the cardboard panels.


[0031] FIG. 1 An array of cardboard specimen section.

[0032] FIG. 2 Depicts a section of aeroboard panel with an inner cone of resin laminated cardboard (aeroboard) without an outer crust.

[0033] FIG. 3 Depicts a section of prefabricated building panel with an inner core of resin impregnated laminated cardboard (aeroboard) with its outer surface thickened with laminations of paper.

[0034] FIG. 4 Depicts a section of aeroboard panel with its outer surface finished with resin impregnated cloth.

[0035] FIG. 5 Depicts a section of aeroboard panel with its outer surface finish with a polymeric cement mortar.

[0036] FIG. 6 Depicts a section of aeroboard with its outer surface covered with a mat of random fibres.

[0037] FIG. 7 Depicts a section of aeroboard with its outer surface covered with a mat of random fibres with delamination guard screws installed.

[0038] FIG. 8 Depicts section of aeroboard panel with its outer surface covered with an adhered random fibre mat, installed delamination guard bolts and a 10 mm overlay of Portland cement mortar.

[0039] FIG. 9 Depicts a section of aeroboard panel with its outer surface covered with an adhered coarse fabric gauze, installed delamination bolts reinforcement and a 10 cm layer of portland cement mortar.

[0040] FIG. 10 Depicts a section of areoboard panel with its outer surface covered with an adhered coarse fabric gauze, installed delamination bolts, fastened steel wire mesh reinforcement and a 3 cm layer of portland cement mortar.

[0041] FIG. 11 Depicts a section of aeroboard panel with a secondary core of wire mesh and polymeric cement mortar designed for use as roof decking.

[0042] FIG. 12 Depicts a section of aeroboard roof decking with inner adhered purlins (rafter) and outer fabric lamination.

[0043] FIG. 13 Depicts a section of aeroboard panel with the columnar air spaces oriented to form the thickness of the panel.

[0044] FIG. 14 Depicts a section of aeroboard panel with the columnar air spaces oriented to a bias alternating pattern.

[0045] FIG. 15 Depicts a section of aeroboard panel with the columnar air spaces to form the thickness of the panel and completely filled with a polymeric cement to present a honeycomb pattern.

[0046] FIG. 16 Depicts a section of aeroboard purlin or rafter element with a secondary core consisting of steel wire mesh embedded in polymeric cement jacket.

[0047] FIG. 17 Depicts the superficial distribution of delamination guard bolts on an aeroboard panel.

[0048] FIG. 18 (a) Depicts a top view of a flanged fastening metal insert.

[0049] FIG. 18 (b) Depicts a section of a flanged fastening metal insert.

[0050] FIG. 19 (a) Depicts a top view of a crossed fastening metal insert.

[0051] FIG. 19 (b) Depicts a section of a crossed fastening metal insert.

[0052] FIG. 20 (a) Depicts an isometric view of a metal insert with u-shaped receptacle.

[0053] FIG. 20 (b) Depicts a top view of a metal insert with u-shaped receptacle.

[0054] FIG. 21 (a) Depicts a section of aeroboard showing installed plumbing elements.

[0055] FIG. 21 (b) Depicts a section of aeroboard showing installed electrical elements.

[0056] FIG. 22 (a) Depicts a section of aeroboard panel attached to a foundation using u-shaped flanged receptacle.

[0057] FIG. 22 (b) Depicts a section of aeroboard panel attached to a foundation using crossed steel bar insert.

[0058] FIG. 22 (c) Depicts a section of aeroboard panel attached to a foundation using side-lapped steel wire mesh extensions.

[0059] FIG. 23 Depicts a section of aeroboard panel attached to a pre-existing concrete wall.

[0060] FIG. 24. Depicts aeroboard panel joint u sing groove and tongue arrangement.

[0061] FIG. 25 Depicts a connection of two aeroboard panels using welded extensions of steel inserts.

[0062] FIG. 26 Depicts a lap joint between two aeroboard panel sections.

[0063] FIG. 27 Depicts a joint between two aeroboard panels using a pattern of interdigitation.

[0064] FIG. 28 Depicts an aeroboard using overlap of embedded steel wire mesh.

[0065] FIG. 29 Depicts attachment of an aeroboard roof decking to a wall formed from aeroboard panel.

[0066] FIG. 30 Stereogram depicting the location of a flanged metal insert within an aeroboard lamination.

[0067] FIG. 31 Depicts a side elevation of the foam digester with the reciprocating hopper in the lowered position.

[0068] FIG. 32 Depicts a side elevation of the foam digester with the reciprocating hopper in the raised position.

[0069] FIG. 33 Depicts various views of the solvent dispenser assembly of the foam digester.

[0070] FIG. 34 (a) Depicts the top view of the foam digester.

[0071] FIG. 34 (b) Depicts the top view of the foam digester with a cut-away section showing the location of the solvent dispenser.

[0072] FIG. 35 Depicts a sectional view of a solvent tank containing a suspended stack of post consumer thermoplastic.


[0073] The alignment of the corrugations parallel to the long axis of the panel typically confers load bearing capability in the long axis. FIG. 2 shows the consequent honey comb pattern of corrugations at the panel end. FIG. 14 shows a contrasting pattern of bias ply orientation applicable where higher stress loads are contemplated in loci perpendicular to the long axis of the panel. FIG. 13 demonstrates yet another preferred embodiment with the columnar air spaces oriented in the short axis to achieve highest compressive strength against stresses perpendicular to the long axis. This is best demonstrated in applications where the panel is itself supported as in floorings and wall veneers. FIGS. 3 through II demonstrates the wide range of options available for the surface crust finish on the aeroboard panels. FIG. 10 with its steel wire mesh and 3 cm thick outer crust is capable of considerable load bearing capability. The highest compressive strength may be achieved using the design shown in FIG. 15. In this preferred embodiment the compressive strength is trebled by the orientation of the corrugations in the short axis and the densification of the completed panel with an aggregate containing polymeric cement mortar. The strategic distribution of delamination guard bolts is shown in FIGS. 17, 22, 23, 25 and 30. FIGS. 18,19,20,22 and 23 show the versatility of the devices available for fastening the aeroboard panels to themselves and other structures.

[0074] FIGS. 25 through 29 all show methods for joining aeroboard panel to one another FIG. 29 is a particularly formidable joint involving element oriented in several plane. The details of the foam digester in FIGS. 31 through 33 help to clarify the structure and operation of the device. The reciprocating hopper (47) allows the foam feedstock to be loaded at ground level and then raised to the digestion chamber trap door. The foam stock pile slides against the outer face of the digestion chamber and cascades inward upon reaching the level of the trap door. Remnants slide downwards along the angled floor of the reciprocating hopper (47). The sidewalls of the reciprocating hopper are hinged forming a recoilable basket which flaps outward to allow comfortable loading. It is secured during travel.

[0075] In FIG. 42 is shown the process in which complex shapes are dimembered into sheet and non-sheet fragment spaces to facilitate liberal contact with the solvent bath. This technique avoids snoballing and gelation which prevents the continued solvent penetration and homogenous dispersion of the target PCTP solute.