Stock material or miscellaneous articles – Composite – Of addition polymer from unsaturated monomers
Reexamination Certificate
1999-02-02
2001-02-27
Thibodeau, Paul (Department: 1773)
Stock material or miscellaneous articles
Composite
Of addition polymer from unsaturated monomers
C428S511000, C428S537100, C428S541000
Reexamination Certificate
active
06194078
ABSTRACT:
TECHNICAL FIELD AND BACKGROUND OF THE INVENTION
The invention can be used with solid wood and with thin veneers of such woods. For purposes of illustrating the invention of this application, principal emphasis will be placed on the method of hardening veneers of oak and maple, although other species of wood can be treated, as well.
Applicant's process of manufacturing hardwood flooring includes the steps of forming veneers of about {fraction (1/10)} inch in thickness, and then adhering the veneer strips to spaced-apart backing blocks or to solid core materials. The side-to-side spaces between the adjacent blocks provide flexibility to the finished flooring strip while permitting the use of inferior grades of wood for the hidden base portions of the product. The veneer surfaces are substantially blemish-free and when finished form the exposed, decorative surface.
The attractiveness and wear resistance of the flooring strips can be enhanced by hardening the veneers before adhering them to the backing blocks. This process involves forming a closely and densely-stacked bundles of veneer blanks which are loaded into a reactor vessel where the blanks are exposed to a solution containing monomethylmethacrylate (“MMA”). Bundling of the blanks greatly increases the quantity of blanks which can be processed during a single cycle.
Vacuum and pressure conditions are used to impregnate the MMA into the cell structure of the blanks. When cured, the blank is substantially more wear and damage resistant without affecting the attractiveness, natural appearance and other desirable characteristics of the product. Dyes may be used during this process to achieve desired finish colors in the blanks.
One problem observed during this process is the tendency of the blanks to stick together so that they must be manually separated. This causes damage to the surface and renders the blank unsuitable for use. In addition, hardening the blanks while bundled can also cause warping and splitting. These problems occur variably, but tend to be more prononuced with maple than with oak—two common hardwood flooring woods.
One procedure which reduced the sticking somewhat was sandwiching alternate blanks of oak and maple in the bundle, since oak and maple tend to stick to itself more readily than to each other. However, alternating the blanks and then separating them back into respective sets of oak and maple blanks is very labor intensive, and creates difficulties in producing the proper proportions of oak and maple in needed colors.
It has been determined that the use of Polyethylene Glycol (“PEG”) in a blend with the MMA substantially reduces the tendency of the flooring blanks to stick together during the hardening process. The process also enhances the stability of the blanks, thus reducing the tendency of the blanks to crack, warp, split, cup and crown.
SUMMARY OF THE INVENTION
Therefore, it is an object of the invention to provide a method of hardening wooden flooring blanks which utilizes Polyethylene Glycol (“PEG”) in a blend with a monomethylmethacrylate (“MMA”) hardener to substantially reduce the tendency of bundled flooring blanks to stick together after the hardening method is completed.
It is another object of the invention to provide a method which reduces cracking, warping, splitting, cupping and crowning in wooden flooring blanks and in the end product.
It is another object of the invention to provide a method which reduces cracking, warping, splitting, cupping and crowning in wooden flooring blanks and in the end product, while hardening the flooring blank during the same process.
It is another object of the invention to provide a wooden flooring blank and a finished hardwood flooring product produced according to the method of the application.
These and other objects of the present invention are achieved in the preferred embodiments disclosed below by providing a method of hardening wooden flooring blanks by impregnating the wooden flooring blanks with a hardener while the wooden flooring blanks are in a bundle, wherein the bundled hardened wooden flooring blanks have improved separation characteristics following completion of the impregnation treatment. The method includes the steps of assembling a plurality of wooden flooring product blanks into a bundle of blanks in surface-to-surface contact with each other and enclosing the wooden flooring blanks in a pressure vessel. The pressure vessel is evacuated and an effective quantity of a hardening composition for being impregnated into the wooden flooring blanks is introduced into the pressure vessel. An effective quantity of a polyethylene glycol composition is introduced into the pressure vessel. The wooden flooring blanks are soaked in the hardening composition and the polyethylene glycol composition for a predetermined period of time. Increased pressure is applied to the wooden flooring blanks to drive the hardening composition and the polyethylene glycol composition into the wooden flooring blanks.
According to one preferred embodiment of the invention, the step of soaking the wooden flooring blanks in the hardening composition and the polyethylene glycol composition for a predetermined period of time is carried out at greater than atmospheric pressure.
According to another preferred embodiment of the invention, the soaking step includes a first soaking step at ambient pressure and a second soaking step at greater than atmospheric pressure.
According to yet another preferred embodiment of the invention, the method includes the step of removing the hardening composition and the polyethylene glycol composition from the vessel before applying increased pressure to the wooden flooring blanks.
According to yet another preferred embodiment of the invention, the method includes the application of heat to the wooden flooring blanks along with the increased pressure.
According to yet another preferred embodiment of the invention, the hardener is a monomethylmethacrylate curable upon exposure to heat.
According to yet another preferred embodiment of the invention, the wooden flooring blanks comprise blanks chosen from the group consisting of parquet blocks, veneer strips and solid wood.
According to yet another preferred embodiment of the invention, the wooden flooring blanks comprise blanks chosen from the group consisting of oak and maple.
According to yet another preferred embodiment of the invention, the method includes the step of introducing a wood stain into the pressure vessel with the hardening composition for staining the wood blank while they are hardened.
According to yet another preferred embodiment of the invention, a method of hardening wooden flooring blanks by impregnating the wooden flooring blanks with a hardener while the wooden flooring blanks are in a bundle is provided, wherein the bundled hardened wooden flooring blanks have improved separation characteristics following completion of the impregnation treatment. The method includes the steps of assembling a plurality of wooden flooring product blanks into a bundle of blanks in surface-to-surface contact with each other, enclosing the wooden flooring blanks in a pressure vessel, evacuating the pressure vessel, and introducing into the vessel a blended hardening composition comprising a catalyst and an effective quantity of a catalyst-curable monomethylmethacrylate for being impregnated into the wooden flooring blanks and an effective quantity of a polyethylene glycol composition. The method also includes the steps of soaking the wooden flooring blanks in the blended hardening composition for a predetermined period of time, draining the hardening composition from the pressure vessel, applying pressure to the wooden flooring blanks to drive the hardening composition and the polyethylene glycol composition into the wooden flooring blanks; applying heat to the wooden flooring blanks to accelerate the catalyst to thereby cure the monomethylmethacrylate, and removing the bundle of wooden flooring blanks from the pressure vessel, whereby the wooden flooring blanks have increased ha
Adams, Schwartz & Evans P.A.
Rickman Holly C.
Thibodeau Paul
Triangle Pacific Corp.
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