Building materials from needle-punched fiber mats with granular heat-activated adhesives

Abstract

Dry adhesives are embedded within needle-punched fiber mats used for manufacturing wood-like building materials. During a cross-lapping operation that lays large ribbons of combed fibers (such as nylon fibers from shredded carpets) on top of a large moving conveyor, one or more layers of granular, pellet, fibrous, film, or other dry adhesive are embedded within the loose mass of fibers. For example, dimpled rollers, shaker trays, or similar devices loaded with granular or pelleted adhesives can be positioned above the conveyor, between cross-lapper machines. The fiber mass with embedded adhesive is then needle-punched into a stable, compact, flexible form that can be stored and shipped. When desired, the mats are run through a heated press that melts the adhesive, converting it into a binder that turns the mats into stiff sheets of material comparable to plywood.

Description

PRIORITY CLAIM [0001] This application claims priority under 35 USC 120(e) based on U.S. provisional application 60 / 408,946, filed on Sep. 7, 2002.BACKGROUND OF THE INVENTION [0002] This invention relates to solid materials handling and to chemical adhesives, and discloses methods for converting needle-punched fiber mats (from sources such as shredded recycled carpets) into waterproof building materials, such as substitutes for plywood, roofing shingles, etc. [0003] A method for creating sheets of wood-like materials, comparable to plywood but essentially waterproof and bug-proof, using nylon fibers obtained from shredded discarded carpet segments, is described in published PCT application WO 01 / 76869 (arising from PCT / US01 / 11895), by Forrest Bacon et al, the same Applicants herein. The contents of that published application are hereby incorporated by reference, as though set forth fully herein. [0004] The above-cited PCT application describes a new use for needle-punched fiber mats...

AI Technical Summary

Benefits of technology

[0029] This type of adhesive deposition, carried out on the same conveyor system that is being used to create the thick mass of nylon fibers that will be compressed and then needle-punched, can distribute and embed a “hot melt” adhesive throughout essentially the entire thickness (or any targeted portion thereof) of a needle-punched fiber mat, regardless of how thick or heavy the needle-punched mat will be. The resulting mats are highly stable, and can be stored for months before the heated compression step.

[0030] When the needle-punched mat containing the hot-melt adhesive is passed through a heated press, the adhesive will melt into a highly sticky liquid that will be distributed throughout the entire thickness of the mat. This can generate a hardened wood-like material with a high level of consistency, uniformity, and strength. Accordingly, by allowing a manufacturer to eliminate the need for expensive two-component liquid adhesives that will release gas bubbles shortly after the two components are mixed, this method can reduce the total costs of the building materials that are being manufactured.

Problems solved by technology

However, there is a not a high level of demand for these mats, since those uses are limited, and people generally prefer to have rubbery foam underlayers, which provide a spring-like bouncy feel, installed beneath carpets in homes and apartments.

The main drawback and limitation of this manufacturing process is that two-component adhesives which will release gas bubbles, after being mixed together, tend to be expensive, and make up the large majority of the total cost of manufacturing these types of boards.

However, in the tests that were carried out prior to this invention, less expensive types of adhesives were not able to provide the consistency and uniformity that will be required to achieve widespread acceptance and commercialization of these types of wood-substitute materials.

The primary obstacle that prevented the successful use of inexpensive adhesives, prior to this invention, was the difficulty that was encountered in getting candidate adhesives to somehow permeate, diffuse, or otherwise be distributed in an even, consistent, uniform, and reliable manner, throughout the entire thickness of a needle-punched fiber mat.

As anyone who has personally inspected a needle-punched mat made from shredded carpets can attest, the thickness and density of the mat, combined with the dense and complex intertwining of the fibrous matrix in the mat, poses a formidable and daunting challenge to any attempt to successfully drive any form of liquid, granular, or powdered material through the mat, in an even, consistent, and uniform manner.

This poses a major challenge, since evenness, consistency, and uniformity are essential to sheetwood materials that must compete against plywood or OSB.

If even a single small seam fibrous mat material, which did not receive enough adhesive to harden properly, is present in a sheet of a plywood substitute, then that entire sheet will be unreliable and even dangerous to use in a building; it will be effectively worthless, since its sale might subject the seller to large legal liabilities if it is incorporated into a building and then subsequently fails, due to the one small seam.

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