Structural panel

A structural panel includes a core and first and second facing sheets. The core has bonding surfaces on first and second, opposite sides thereof. The first facing sheet is a non-thermoplastic, fire retardant facing sheet having an inner surface bonded to the bonding surface on the first side. The second facing sheet is bonded to the bonding surface on the second side. The first facing sheet is fire retardant or non-flammable and the core is at least fire retardant. The structural panel finds particular utility as a building-cladding panel.

BACKGROUND

Structural panels are used in a wide variety of situations. They can be used in creating support platforms for furniture, such as shown in U.S. Pat. No. 5,868,081. They can also be used in the manufacture of crating and in architectural situations to create facing panels for walls or other building structures. For example, structural panels in the form of plywood sheathing can be used to create timber shear walls. Structural panels can also be used for knock-down crates, garden sheds, interior wall panels, music instrument cases, box trailers, hunting cases, van conversions, cabinetry, outdoor signs, podiums, subfloors, roof and wall structural sheathing product, barn walls, truck panels, etc.

SUMMARY

A structural panel includes a core and first and second facing sheets. The core has bonding surfaces on first and second, opposite sides thereof. The first facing sheet is a non-thermoplastic, fire retardant facing sheet having an inner surface bonded to the bonding surface on the first side. The second facing sheet is bonded to the bonding surface on the second side. The first facing sheet is fire retardant or non-flammable and the core is at least fire retardant.

In some examples the structural panel can include one or more the following. The first facing sheet and the core can be mold and mildew resistant. The core can include protrusions and cavities on said first and second sides, the protrusions defining at least some of the bonding surfaces, with at least some of the bonding surfaces being spaced apart bonding surfaces; at least some of the protrusions and cavities can be separated by saddles, the saddles having a concave surface portions extending between the protrusions and convex surface portions extending between the cavities. The facing sheets can be made from one or more of: ferrous or nonferrous metal, including galvanized steel, powder coated steel, or aluminum; fiberglass reinforced plastic, thermoset plastic, and ballistic sheet material. The second facing sheet can be a non-thermoplastic, fire retardant second facing sheet.

A building-cladding panel includes a core, a thermoset adhesive, and non-thermoplastic first and second facing sheets. The core is a fire retardant, mold and mildew resistant core having bonding surfaces on first and second, opposite sides thereof. The core includes protrusions and cavities on said first and second sides, the protrusions defining at least a majority of the bonding surfaces, at least a majority of the bonding surfaces being spaced apart bonding surfaces. The first and second facing sheets each have an inner surface bonded to the bonding surface on the first and second sides with the thermoset adhesive. The first facing sheet includes at least one of: ferrous or nonferrous metal, including galvanized steel, powder coated steel, or aluminum; fiberglass reinforced plastic, thermoset plastic, or ballistic sheet material. The first facing sheet is fire retardant or non-flammable. The core is at least fire retardant.

Other aspects and advantages of the present technology can be seen on review of the drawings, the detailed description and the claims, which follow.

DETAILED DESCRIPTION

A detailed description of embodiments of the present technology is provided with reference toFIGS. 1-4.

FIG. 1is an exploded isometric view of a structural panel10including a core12having first and second sides14,16. Referring also toFIG. 2, core12includes first and second protrusions18,20extending in opposite directions towards the first and second sides14,16. First protrusions18have first bonding surfaces22at first side14while second protrusions20have second bonding surfaces24at second side16. First protrusions18created first cavities26extending towards second side16while second protrusions20create second cavities28extending towards first side14. In this example the first bonding22surfaces created by first protrusions18create larger surface areas than the second bonding surface24created by second protrusions20. In some examples the bonding surfaces created by each protrusion can be equal. Also, the bonding surfaces created by the protrusions on either side can have different surface areas. The bonding surfaces can be evenly spaced as disclosed, or not.

In this example first and second protrusions18,20and first and second cavities26,28are separated by saddles30. Saddles30on first side14have concave portions32extending between adjacent first protrusions18and convex portions34extending between adjacent and second cavities28. The saddles on second side16have similar shapes.

The material from which core12is made can be ABS (acrylonitrile-butadiene-styrene) thermoplastic polymer. A rigid, UL listed fire-rated Acrylic ABS sheet designed to retard microbe development using antimicrobial technology to inhibit the growth of mold and mildew commonly found in architectural environments which passes ASTM E84 Steiner tunnel test can be used; these sheets have been treated to be fire-retardant so as to reduce flammability of the panel. One example of such a fire-rated antimicrobial material is Royalite R52 AM PVC/acrylic from PolyOne Corporation of Clayton Mo. Core12can also include insulating material, such as EPS (expanded polystyrene) foam within the open regions to improve the thermal insulation R-value of the structural panel10.

Structural panel10also includes first and second facing sheets36,38bonded to bonding surfaces22,24on the first and second sides14,16of core12. In some examples prior to bonding, both sides of core12and the inner surfaces of facing sheets36,38are sanded to help achieve a maximum bond. The sanded core and facing sheets can be subjected to Corona treatment, a high-frequency discharge to increase the adhesion of the facing sheets to the core. Adhesive layers40,42are applied to the inner surfaces of first and second facing sheets36,38. This is followed by placing the adhesive sides of the facing sheets against the bonding surfaces of the core to create a pre-cured structural panel. The pre-cured structural panel is then placed in a press, often heated, typically for hours or days, to complete the bonding process. Although not presently preferred, in other examples the adhesive can be applied directly to the first and second bonding surfaces22,24or to both the facing sheets and the bonding surfaces. While a range of adhesives can be used, a moisture curing polyurethane adhesive has been found to be very effective in providing a strong bond suitable for use when structural panel10is to be used as interior or exterior wall panels. One example is Vibra-Tite® 801LV Polyurethane adhesive from ND Industries, Inc. of Clawson, Mich.

Core12and facing sheets36,38can be treated to inhibit the growth of mold and mildew commonly found in architectural environments. Pre-treated ABS sheets which have already been treated to be both fire-retardant and antimicrobial can be obtained from a commercial source and used for core12. These materials are preferably manufactured in plants that are ISO 9001-2000 certified and materials are manufactured under good manufacturing practice (GMP) guidelines. The specific materials from which core12and facing sheets36,38are made can affect the choice of the treatment.

Various non-thermoplastic materials can be used for facing sheets36,38; examples include: ferrous and nonferrous metal, including galvanized steel, powder coated steel, or aluminum; fiberglass reinforced plastic, thermoset plastic, and ballistic sheet material. Regarding ballistic sheet material, which can be referred to as fiber reinforced thermoplastic ballistic material, it can be post-formed and co-molded for strategic reinforcement to increase design flexibility, improve specific strength and lower component weight for high strain-to-failure ballistic resistance; ballistic sheet material is commercially available from, for example, PolyOne—Polystrand of Englewood, Colo. Ballistic sheet materials can be made using DuPont's Kevlar® aramid fiber. In one example fire-rated antimicrobial facing sheets36,38are manufactured from recycled PVC/acrylic resin and are available from PolyOne Corporation of Clayton Mo. as Royalite R552 Flame Rated Sheet. In another example facing sheets36,38are made from fiberglass reinforced plastic by the Kal-Lite Division of Kalwall Corporation of Bow, N.H. Facing sheets36,38can be made from one or more materials. Facing sheet36can be made from the same or different materials as facing sheet38. Facing sheets36,38are preferably made from fire retardant material or a non-flammable material, also referred to as a noncombustible material, As used in this application, a fire retardant material is a material which meets the ASTM E84 test standard, and a non-flammable material is a material which meets the ASTM E-136 test standard.

A structural panel for use as a building-cladding panel on interior or exterior walls can be made to provide significant structural strength while being relatively thin, such as having: a core thickness42of between about 0.187 inch and about 0.750 inch; a facing thickness from about 0.020 inch and about 0.125 inch; resulting in a total panel thickness from about 0.250 inch to about 1 inch. Such a building-cladding panel can have a fire retardant core and fire retardant or non-flammable facing sheets to enhance the fire resistance of the building. Structural panel can be printed with artwork or logos. When used as a weather resistive barrier, if enclosed it will provide some thermal insulation and will increase the R-value.