Stock material or miscellaneous articles – Composite – Of polyamidoester
Reexamination Certificate
2001-01-22
2004-10-12
Juska, Cheryl A. (Department: 1771)
Stock material or miscellaneous articles
Composite
Of polyamidoester
C428S425100, C428S147000, C428S165000, C428S913300, C442S394000, C442S395000, C442S412000, C442S417000
Reexamination Certificate
active
06803110
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to decorative laminate assemblies and methods for producing the same, and more specifically, decorative laminate assemblies with enhanced moisture resistance and dimensional stability, which qualities are particularly useful in flooring applications where there will be repeated or prolonged exposure to moisture or water.
BACKGROUND OF THE INVENTION
Decorative laminates have been used as a surfacing material for many years, in both commercial and residential applications, where pleasing aesthetic effects in conjunction with desired functional behavior (such as superior wear, heat and stain resistance, cleanability and cost) are preferred. Typical applications have historically included, while not limited to, furniture, kitchen countertops, table tops, store fixtures, bathroom vanity tops, cabinets, wall paneling, office partitions, and the like.
More recently, the applications for decorative laminates have been expanded to include their use as a flooring material in lieu of more expensive real wood, stone or ceramic tile, less sanitary and rugged carpeting, as well as less aesthetically attractive vinyl tile or linoleum-like products. However, as discussed in more detail below, existing decorative laminates are not particularly suited in applications where there is repeated or prolonged exposure to moisture and/or water due to their intrinsic hydrophilic properties. Such existing laminates have therefore been primarily limited to residential applications having dry conditions. Accordingly, as discussed further below, there is a need for a decorative laminate that can be used where there is repeated or prolonged exposure to moisture and/or water, thereby overcoming the deficiencies present in existing decorative laminates.
In general, decorative laminates can be classified into two broad categories, namely high pressure decorative laminates (HPDL) and low pressure decorative laminates (LPDL). As defined by the industry's governing body, the National Electrical Manufacturers Association (NEMA) in their Standards Publication LD 3-1995, high pressure decorative laminates are manufactured or “laminated” under heat and a specific pressure of more than 750 psig. Conversely, low pressure decorative laminates are typically manufactured at about 300 psig specific pressure to avoid excessive crushing of their substrate material. The other broad distinction between high pressure and low pressure decorative laminates is that the former are generally relatively thin, typically comprising a decorative surface and a phenolic resin impregnated kraft paper core, and are not self supporting as manufactured. As such they are normally bonded, with a suitable adhesive or glue, to a rigid substrate such as a particleboard or medium density fiberboard (MDF), as a separate step during final fabrication of the end product. Conversely, low pressure decorative laminates are typically comprised of a similar type of decorative surface, without the supporting core layer, which is bonded to a substrate such as particleboard or MDF in a single laminating or “pressing” operation during its manufacture.
Both high pressure and low pressure decorative laminates have historically been manufactured in heated, flat-bed hydraulic presses. With the exception of some newer types of processing equipment, high pressure laminates are typically pressed as multiple sheets in press “packs” or “books” in a multi-opening press (which is usually steam or high pressure hot water heated, and water cooled), with a 30 to 60 minute thermal cycle and 130° C. to 150° C. top temperature. On the other hand, low pressure decorative laminates are typically pressed as a single sheet or “board” in a single opening press (which is usually thermoil or electrically heated) using an isothermal, hot discharge “short cycle” of 30 to 60 seconds with press heating platen temperatures of 180° C. to 220° C. Continuous laminating or “double belt” presses for decorative laminate manufacture blur the above distinctions somewhat, in that their “cycle” times and temperatures are similar to those employed for low pressure decorative laminates. In such a process, pressures are intermediate, typically in the range of 300 to 800 psig, while the continuous laminates themselves are relatively thin, without direct bonding to a substrate material and thus requiring a second fabrication step to do so as is the case with conventional high pressure decorative laminates. The process and product dissimilarities delineated above, as well as more subtle process differences, will be appreciated by those versed in the art.
High pressure decorative laminates are generally comprised of a decorative sheet layer, which is either a solid color or a printed pattern, over which is optionally placed a translucent overlay sheet, typically employed in conjunction with a print sheet to protect the print's ink line and enhance abrasion resistance, although an overlay can be used to improve the abrasion resistance of a solid color as well. A solid color sheet typically consists of alpha cellulose paper containing various pigments, fillers and opacifiers, generally with a basis weight of 50 to 120 pounds per 3000 square foot ream. Similarly, print base papers are also pigmented and otherwise filled alpha cellulose sheets, usually lightly calendered and denser than solid color papers to improve printability, and lower in basis weight at about 40 to 75 pounds per ream, onto which surface is rotogravure or otherwise printed a design using one or more inks. Conversely, overlay papers are typically composed of highly pure alpha cellulose fibers without any pigments or fillers, although they can optionally be slightly dyed or “tinted”, and are normally lighter in basis weight than the opaque decorative papers, in the range of 10 to 40 pounds per ream.
For high wear applications (such as flooring), it is often desirable to have a more highly wear resistant top layer. Accordingly, the overlay papers may contain hard, abrasive, mineral particles such as silicon dioxide (silica), and preferably aluminum oxide (alumina), which is included in the paper's furnish during the papermaking process. Alternatively, the abrasive particles can be coated on the surface of the overlay or decorative papers, during the “treating” process described below, prior to the final lamination step. Further, the abrasive particles can be added to the resin which is used to impregnate the overlay or decorative layers, thus causing the abrasive particles to be deposited on, and to a lesser extent, dispersed within such layers. As is known in the art, if the abrasive particles are deposited on the decorative layer, a separate overlay layer may not be necessary.
Typically, these overlay and decorative print and solid color surface papers are treated, or impregnated, with a melamine-formaldehyde thermosetting resin, which is a condensation polymerization reaction product of melamine and formaldehyde, to which can be co-reacted or added a variety of modifiers, including plasticizers, flow promoters, catalysts, surfactants, release agents, or other materials to improve certain desirable properties during processing and after final press curing, as will be understood by those skilled in the art. As with melamine-formaldehyde resin preparation and additives thereto, those versed in the art will also appreciate that other polyfunctional amino and aldehydic compounds can be used to prepare the base resin, and other thermosetting polymers, such as polyesters or acrylics, may be useful as the surface resin for certain applications.
Optionally, an untreated decorative paper can be used in conjunction with a treated overlay, provided the overlay contains sufficient resin to flow into and contribute to the adjacent decorative layer during the laminating process heat and pressure consolidation so as to effect sufficient interlaminar bonding of the two, as well as bonding of the decorative layer to the core. The equipment used to treat these various surface pap
Drees Terry Paul
Laurence Kenneth John
O'Brien Kevin Francis
Formica Corporation
Juska Cheryl A.
Mayer Brown Rowe & Maw LLP
Salvatore Lynda
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