Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – To produce composite – plural part or multilayered article
Reexamination Certificate
1999-05-20
2001-05-29
Silbaugh, Jan H. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
To produce composite, plural part or multilayered article
C264S255000, C264S259000, C264S308000, C264S319000, C264SDIG005, C264SDIG005
Reexamination Certificate
active
06238609
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to the fabrication of molded articles and, more particularly, to the fabrication of molded articles having relief portions extending therefrom.
BACKGROUND OF THE INVENTION
The Americans with Disabilities Act (ADA) has mandated that signs which are to be utilized for “permanent room identification” in public facilities are to have upper case lettering which is to be raised at least {fraction (1/32)} inch from the background of the sign. Further required by the ADA is the use of Grade II Braille on “permanent room identification” signs which is also to be raised at least {fraction (1/32)} inch from the background of the sign.
Displays, such as signs, having raised characters or images (i.e., “relief” portions) with colors different from a background color thereof are known. Often, such displays are referred to as “one-off” displays because the raised characters and/or images are unique to each display. For example, hotels often mount a sign next to each room to indicate the number of each room. Because each room in a hotel conventionally has a unique number, each respective room number sign will be unique. Co-pending and co-assigned U.S. patent application Ser. No. 09/122,837 describes methods of producing one-off displays, and is incorporated herein by reference in its entirety.
A known method of fabricating displays with raised images and/or characters is to apply preformed characters or images of one color to a substrate of another color. Another known method is to produce an article having images or characters in relief therewith, and then to apply different colors to the raised portions, such as by painting, staining, silk-screening, and the like (often referred to as “tipping”). Unfortunately, these methods may be somewhat labor intensive and may be prone to fabrication errors. Furthermore, displays produced via conventional methods may be rendered aesthetically unpleasing as a result of wear or damage. For example, paint may chip off of a raised portion of a display or an attached raised portion may become detached from the display through wear and/or vandalism.
Displays with raised portions formed by casting a polymeric resin into a mold having one or more recesses can be adversely affected by resin shrinkage during the curing process. Shrinkage of raised portions during curing can induce shear stress that can damage the raised portions and/or display. In addition, displays with raised portions formed by casting a polymeric resin into a mold having one or more recesses can be adversely affected by the presence of air bubbles and voids. For example, polyester resin, by nature, holds air bubbles tenaciously.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide durable, decorative display articles with relief portions extending therefrom that are capable of retaining an aesthetically pleasing appearance even when damaged and subjected to wear and tear.
It is another object of the present invention to provide methods of producing durable, solid surface display articles with relief portions, wherein the relief portions have color schemes different from that of a background.
It is another object of the present invention to provide methods of producing display articles with relief portions formed from polymeric resins that are resistant to damage caused by polymeric resin shrinkage during curing.
These and other objects of the present invention are provided by a method of producing a low stress, decorative article of manufacture having at least one relief portion extending therefrom. A first thermosetting resin, such as an unsaturated polyester, having a first color is cast into recesses formed within a mold surface and such that the first resin is not in contact with the mold surface. Each recess within the mold has a configuration of a respective alphanumeric character, Braille character, or graphic design. The first resin is partially cured to a “B” stage to provide an air inhibited out-of-mold surface. A coating of a second thermosetting resin, such as an unsaturated polyester, is then applied onto the partially cured first resin and onto the mold surface. The coating may have a thickness of up to about 0.10 inch and preferably has an air release agent mixed therewithin. The second thermosetting resin can have one or more colors, and can be configured to cure to a transparent state.
A substrate (e.g., a wood, metal or polymer backing member) having a face is placed in contacting relationship with the second thermosetting resin film. A progressively moving compressive force is then applied to the second thermosetting resin via the substrate to prevent air from becoming entrained within the second thermosetting resin. For example, the mold can be passed through a pair of pinch rollers such that a first compressive force is applied to the substrate and an opposite second compressive force is simultaneously applied to the mold.
The first and second thermosetting resins are then allowed to cure such that the second thermosetting resin film adheres to the substrate face, and such that molecular cross-linking occurs between the first and second thermosetting resins without the second thermosetting resin film imparting shear stress on the first thermosetting resin. The cured article of manufacture is then removed from the mold.
A decorative article of manufacture produced in accordance with methods of the present invention includes a backing member having a thin polymer layer adhered to a face thereof. The polymer layer is devoid of all air bubbles and/or voids and has a thickness of between about 0.003 inch and about 0.050 inch. One or more relief portions extend from the thin polymer layer. Each relief portion is formed from a polymer material that is molecularly cross-linked at an interface with the thin polymer layer.
According to one embodiment, the thin polymer layer and the relief portions have different colors. According to another embodiment, the thin polymer layer and the relief portions have the same color. According to another embodiment, the thin polymer layer is transparent such that such that the backing member face is visible therethrough.
Exemplary decorative articles produced by the above process include architectural facing, signs, displays and the like. Signs produced in accordance with the present invention are particularly suitable for use where a durable finish and surface is desired. Because the relief portions of an article of manufacture produced in accordance with the present invention have the same color throughout the thickness of the resin material, chips and other forms of wear do not have a detrimental appearance to the article. Decorative articles may be produced to simulate almost any type of surface and may have almost any pattern and color scheme desired when produced according to the processes of the present invention. Furthermore, fabrication methods according to the present invention can be more efficient than paint inlay or overlay methods and can produce articles that are more authentic looking than articles with painted surfaces.
Because the thermosetting resin applied to the backing member face is a thin film, decorative articles produced by the above process experience little or no shrinkage during curing.
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Lee Edmund H.
Myers Bigel & Sibley & Sajovec
Silbaugh Jan H.
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