Stock material or miscellaneous articles – Composite – Of inorganic material
Reexamination Certificate
1997-06-11
2002-05-28
Yamnitzky, Marie (Department: 1774)
Stock material or miscellaneous articles
Composite
Of inorganic material
C428S195100, C428S322200, C428S525000, C428S526000, C428S913000, C156S067000, C156S307400
Reexamination Certificate
active
06395408
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to decorative laminates formed of a plurality of resin impregnated cellulosic sheets. More particularly, this invention relates to high pressure decorative laminates which incorporate a material which is visibly luminescent upon exposure to ultraviolet light, and to methods of producing the same.
BACKGROUND OF THE INVENTION
Conventionally, high pressure decorative laminates are made of two essential layers: a core layer and a surface layer. The core layer constitutes a bottom or supporting layer onto which the other layer is bonded. In normal high-pressure laminate manufacture, the core layer consists of a plurality of cellulosic sheets. The core sheets are generally made from a kraft paper impregnated with a laminating resin. Laminating resins commonly used for the core layer include phenolic, melamine, amino, epoxy, polyester, silicone, and diallyl phthalate resins to name a few. The industrially preferred laminating resin for decorative laminates is a phenolic resin made from the reaction of phenols with formaldehyde.
Placed above the core layer is a decorative layer which is generally formed of one or more sheets of cellulose pigmented paper containing a print, pattern design or solid color that has been impregnated with a transparent resin, such as melamine, amino, epoxy, polyester, silicone, and diallyl phthalate resins to name a few. The preferred and typically used resin for the papers of the decorative layer is melamine-formaldehyde resin. The cured melamine-formaldehyde resins are colorless, resistant to light and heat, as well as being resistant to a variety of solvents and stains.
When the decorative layer of the laminate includes a printed pattern, it is commonly covered with what is generally referred to as an overlay, which is typically a high-quality alpha cellulose paper impregnated with a melamine-formaldehyde resin. This layer protects the decorative print from external abuse such as abrasive wear and tear, harsh chemicals, burns, spills and the like. It is primarily the melamine-formaldehyde resin which accounts for these protective properties of the laminate. The alpha-cellulose paper acts as a translucent carrier for the water-thin resin, imparts strength to the melamine-formaldehyde resin, maintains a uniform resin thickness in the overlay by acting as a shim, and controls resin flow.
The core layer, decorative layer and the overlay surface layer (when needed) are stacked in a superimposed relationship, between steel press plates and subjected to a pressure and temperature for a time sufficient to cure the laminating resins impregnating the respective layers. The elevated temperature and pressure actually cause the impregnated resins within the sheets to flow, which consolidates the whole into an integral mass known as the laminate. These laminates are used as surfacings for floors, counter tops, table tops, furniture, store fixtures, and the like. Examples of conventional high pressure decorative. laminates are given, for example, in U.S. Pat. No. 3,418,189 to Grosheim et al., U.S. Pat. No. 4,311,748 to Casey et al., U.S. Pat. No. 4,473,613 to Jaisle et al., and U.S. Pat. No. 4,741,968 to Dion et al., each of which is incorporated herein by reference.
SUMMARY OF THE INVENTION
In accordance with the invention, a decorative laminate is provided which is comprised of a core layer, a decorative layer and an optional surface layer or overlay which are stacked and laminated under heat and pressure. The core layer includes one or more melamine or phenolic resin impregnated sheets of kraft paper or the like; the decorative layer includes one or more melamine impregnated printed sheets; and the optional overlay includes one or more thin protective melamine impregnated paper layers. In one embodiment of the invention, an image or pattern is printed on one or more of the decorative paper layers with a ink including a photoluminescent material to provide an image or pattern therein which is visible when exposed to a source of ultraviolet light (i.e., a source of electromagnetic radiation in the range of about 200-400 nm). The term “photoluminescent” is used herein to denote a material which is either visibly phosphorescent (i.e., where there is a continued luminescent radiation after termination of the exciting radiation) or visibly fluorescent (i.e., where the luminescent radiation ceases as soon as the exciting radiation is removed). The decorative paper layers are then each saturated with a clear resin, such as melamine-formaldehyde, and stacked with a core layer and, optionally, the overlay, and laminated under heat and pressure.
In a further embodiment, the photoluminescent material is visibly phosphorescent after exposure to exciting radiation in the visible range.
In another embodiment, one or more of the overlay papers and/or decorative layer papers are impregnated prior to lamination with a mixture of a transparent resin, preferably melamine, and a photoluminescent material. As a result, the entire upper surface of the laminate visibly luminesces in the presence of ultraviolet light.
In a still further embodiment of the invention, one or more of the decorative layer papers is saturated with a mixture of resin and a photoluminescent material, or is provided with a design or pattern printed with an ink including a photoluminescent material, and is then low pressure laminated or thermofused to a substrate such as particle board, fiber board or the like.
It is envisioned that the invention could be used to provide a unique and appealing appearance when used as the surfacing for a wide variety of applications, including bowling lanes, game tables, counter-tops, dance floors, and signs such as “exit” signs. The invention could also be used to provide selectively viewable printed information, such as manufacturer identifiers, for otherwise conventional decorative laminate applications.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention is directed to decorative laminates which incorporate a photoluminescent material. In a first embodiment of the invention, the decorative laminate comprises a core layer, a decorative layer, and preferably an overlay. The core layer is of known construction and consists of one or more cellulosic sheets, preferably formed of a kraft paper, impregnated with a laminating resin. Any of the conventional laminating resins commonly used for the core layer, such as phenolic, melamine, amino, epoxy, polyester, silicone, and diallyl phthalate resins, to name a few, may be used. The preferred laminating resin is a phenolic resin made from the reaction of phenols with formaldehyde.
Placed above the core layer is a decorative layer which is formed of one or more cellulosic sheets, preferably sheets of alpha cellulose paper. Using a printing composition including an effective amount of a photoluminescent material, a design or pattern is applied to the surface of one or more of the cellulosic sheets forming the decorative layer. It is generally preferable to apply the design or pattern to the sheet or sheets which, in the final laminate, will be positioned furthest from the core layer to enhance the intensity of the luminescent radiation emitted from the surface of the laminate. The design or pattern is preferably applied to the outermost paper sheet or sheets. The manner in which the printing composition is applied to the sheet or sheets is not critical, and any known printing method, such as screen printing, gravure printing or the like, may be used.
The printing composition used in accordance with the invention includes a photoluminescent material dispersed in a suitable vehicle which offers the flow characteristics desired for the selected printing method. The photoluminescent material is provided in an amount which is effective to cause the printed design or pattern to be visibly luminescent in the final laminate. Many types of known ultraviolet light sensitive dyes or pigments may be used. In addition, visible light sensitive phosphorescent materials may also be used. Sel
Dumond Robert A.
Nelson Daniel C.
McCormick Paulding & Huber LLP
Pioneer Plastics Corporation
Yamnitzky Marie
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