This invention relates to a method of manufacturing a stiff engineered composite. More particularly, this invention relates to a method of producing stiff mycelium bound parts.

As is known, conventional methods for producing nonstructural boards rely on compressing wood veneer sheets, fibers, or particles and binding them together with resin to form composites like hardwood plywood and medium density fiberboard, which are used for applications such as furniture and fixtures, cabinetry, paneling, molding and athletic equipment. The ingredients for these typical non-structural boards require considerable pre-processing, and the feedstocks, especially timber and resins, are subject to considerable price volatility. Additionally, many of the resins used to produce non-structural boards are carcinogenic and can emit volatile organic compounds (VOCs).

Much like nonstructural boards, structural boards are produced by compressing wood veneer sheets, fibers, or particles and binding them together with resin to form composites like oriented strand board (OSB) and softwood plywood. OSB and softwood plywood are used for applications such as wall sheathing, floor sheathing, and concrete framework. These structural boards face the same concerns that nonstructural boards face because they use similar feedstocks and resins.

Many structural and nonstructural boards are used for applications in furniture, cabinetry, and fixtures where they must be cut, milled, and sanded to form the desired shape. Such post processing is expensive and time consuming and creates material waste as the products are shaped. Plastics are also used for these applications and require expensive tools and machines for molding in their production processes.

US Published Patent Application 2008/0145577 describes various techniques for making self-supporting composite bodies comprised of discrete particles and a network of interconnected mycelium cells bonding the particles together. As described therein, the composite bodies may be formed into panels as well as into panel systems with a composite core.

It is an object of this invention to provide an improved process for the manufacture of a compressed composite body of particle/mycelium.

Briefly, the invention provides a method of achieving adhesion between a matrix of fungal mycelium and a slurry of particles and/or fibers (natural or synthetic) through a heated compression process.

US Published Patent Application 2008/0145577 has demonstrated that fungal mycelium can bind natural (lignocellulosic and chitinous waste streams) and/or synthetic (fiberglass) particles together during a controlled incubation process. The mycelium in the latter instance serves as a grown adhesive, digesting a portion of the particles and fibers while encapsulating the slurry in a network of a vegetative tissue.

The process described within demonstrates that the extracellular matrix of mycelium, known as the matrix layer of the cell wall and comprised of polysaccharides (alpha and beta glucans), polymerized amino sugars (N-glucosamine, chitin), monoproteins, and phosopholipids, can serve as a traditional adhesive when heated and dried concurrently. The mycelium is either grown on, or mixed with, an engineered substrate of natural and/or synthetic particles and/or fibers and then compressed under heat and dried to desired geometry.

The heating of the mycelium matrix actually provides value in two places, which makes this process distinctly different from the prior art. The fungal cell wall is comprised of chitin and glucans. The glucans, when heated and saturated with the moisture embedded within the composite, begin to flow like a traditional resin and when dried stick the particles together beyond the traditional mycelium matrix.

By creating sheets of material made from particles bound together with mycelium (hereinafter “the biocomposite material”) and compressing these sheets together, bio-based nonstructural boards can be created with feedstocks. The sheets of biocomposite material can be grown together or compressed together with heat to set and dry the final product. The sheets of biocomposite material can vary in product density, fiber content, particle size, and fiber orientation to selectively promote specific mechanical properties (screw hold strength, core shear, modulus of elasticity).

Further, a large mass of mycelium can be cultivated on particles or fibers, milled to a consistent particle size and then pressed in a constrained heated tool.

Additionally, VOCs are not a concern for structural boards produced in this manner because no VOC emitting resins are used in the production process, and the cross-linking occurs between the biochemical construct of the fungal cell wall.

There are significant mechanical advantages garnered from compressing sheets of mycelium bound particles into a single cohesive product with heightened temperatures (200° F.-650° F.) while compressing the biocomposite material at a pressure of from 10 to 1500 psi. These advantages include enhanced modulus of rupture and elasticity (stiffness), and the ability to layer sheets of varying particles size to achieve greater stiffness or dimensional stability (squareness, flatness).

Other materials, including veneers, textiles, or laminates, that are comprised of wood, plastics (polyester scrim), foam, natural fibers, stone, metal, or the like can be grown and bound to the face or internal structure of the mycelium and particle sheets. These laminates can be stacked and interlaid to the mycelium colonized particle sheets, and then compressed to a desired form (flat or molded).

Structural boards can be created by compressing thick blocks of grown material or layered sheets of grown material (particles and/or fibers bound by mycelium) while drying with heat (radiation, conduction, or convective).

Orienting particles within an engineered substrate and then preliminarily binding these with mycelium creates a bio-based product that does not emit VOCs.

The compressed biocomposite material can be easily and cheaply shaped during production. The grown material can be compressed in an inexpensive mold (fiberglass, carbon fiber, composite, wooden and/or metal, e.g. aluminum), giving the material the desired shape and material properties without creating waste. The final product can be dried in the tool to promote cross-linking between the natural polymers within the mycelium, which can occur within the magnitude of minutes.

The grown material can also be compressed in a conductive tool that is heated as well to the final shape, either with a heated platen or inserted cartridges.

These and other objects and advantages of the invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings wherein:

