Water-resistant plywood substitutes made from recycled carpets or textiles

Abstract

A method is disclosed for using discarded carpet segments or other recycled textiles to make wood-like material in sheets that are comparable to plywood. The carpet segments or other recycled materials are shredded, then layered across a slow-moving conveyor to form a thick, low-density belt of fibers. This belt is compressed between rollers, and then needle-punched, using needles with surface barbs that pull fibers downward and upward. This needle-punching causes fibers inside the mat to be pulled into vertical alignment (i.e., perpendicular to the top and bottom surfaces of a horizontal mat), to form a needle-punched mat that will hold together without chemical adhesives. A binder material is then applied to at least one and possibly both surfaces of the mat, by means such as spreading or spraying a liquid binder on either or both surfaces of the mat, or stretching a continuous film of the binder material across either or both surfaces of the mat. The polymer-coated fiber mat is then compressed while the binder hardens and cures, to form hardened wood-like product, in sheet form, without requiring melting of the nylon or other synthetic fibers inside the material. In an alternate embodiment, nylon fibers blended with polypropylene or other polyolefins can be heated and compressed to a temperature which (i) melts the polypropylene, causing it to act as an adhesive, and (ii) creates a “heat set” in the nylon fibers. These materials are strong, durable, highly resistant to cracking or splitting, and highly resistant to water infiltration or damage, and offer highly useful substitutes for plywood, particleboard, and other forms of wood and lumber.

Description

RELATED APPLICATION[0001]This application claims priority based upon Patent Cooperation Treaty application PCT / US01 / 11895, which was published as WO 01 / 76869.BACKGROUND OF THE INVENTION[0002]This invention is in the field of solid materials handling, and relates to using recycled material (especially from discarded carpet segments) to create large sheets of wood-like material, comparable to sheets of plywood, that is highly resistant to infiltration or damage by water and various chemicals and solvents.[0003]Various methods are known for converting recycled waste products containing nylon and other plastics into relatively narrow planks. Those recycled planks typically resemble single boards, rather than sheets of plywood, and typically have widths only up to about 15 cm (6 inches) wide. Most manufacturing processes used to create such board-substitutes from recycled wastes require a relatively high level of melting of the nylon or other plastic material in the recycled feedstock mi...

AI Technical Summary

Benefits of technology

[0038]This mat is then “needle-punched”, using an array of needles with barbs or nicks which can grab and yank fibers downward and possibly upward. This needle-punching operation causes large numbers of fibers inside the mat to be yanked and pulled into a roughly vertical alignment (i.e., roughly perpendicular to the top and bottom surfaces of a horizontal mat), to form a dry compressed mat.

[0041]Tests to date indicate that these materials are strong, durable, highly resistant to cracking or splitting, and highly resistant to water infiltration or damage. Accordingly, these materials, made from discarded carpet segments, offer very good water-resistant substitutes for plywood, particleboard, and other forms of wood and lumber.

Problems solved by technology

Accordingly, such manufacturing processes require large amounts of energy, to heat up the recycled materials to their melting points.

A number of important and previously insurmountable obstacles apparently have prevented any such efforts from succeeding.

First: it would require prodigious amounts of energy to heat the bulk and volume of material that would be involved in large-scale manufacturing of plywood substitutes, to the high temperatures that would be necessary in a manufacturing operation that requires extensive melting of recycled plastic or synthetic feedstock material.

Second: even if the necessary “average” temperatures could be reached, non-uniform heating would lead to unacceptable fault lines, fracture zones, weak spots, and other flaws, when large sheets of hard material are being manufactured.

Those flaws would result in uneven strength, poor quality, and unreliability, if plywood-like sheets are being created, in ways that do not occur when narrow planks are created using melt-and-mold processes as used in the prior art.

Third: the problems of uneven heating (and resulting poor quality) are aggravated by the fact that when matted layers of fibers are heated, they respond in a manner directly comparable to thick woolen blankets.

Fibrous mats are thermal insulators, and the type of thermal insulation they provide will thwart and frustrate any effort to establish the type of uniform and consistent heating that is required for a melt-and-mold manufacturing operation.

Fourth: serious problems arise when attempts are made to mix different types and grades of discarded nylon, and / or various other types of recycled plastics.

Fifth: still more serious problems arise, whenever attempts are made to force a liquified or paste (such as an adhesive, a melted component, etc.) to permeate, evenly and uniformly, through a dense layer of matted fibers.

For these and other reasons, all prior efforts to create large sheets of plywood-like material from discarded carpet segments (or other recycled textiles) apparently have failed.

None of those efforts ever succeeded, and the failed attempts typically were never published or patented.

The most common problems encountered were excessive weight, excessive cost, and inadequate strength and / or durability (especially under wet conditions), for sheets of material that must compete against plywood in order to become commercially successful.

Despite decades of effort by hundreds of skilled people, carpet recycling still has not become fully viable on an economic basis.

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